METHODS FOR POST-PROCESSING AND FOR HANDLING OF MEMS CHIPS

Abstract

In a method of post-processing MEMS chips comprising MEMS structures arranged on a carrier material and having at least one projection region of projecting material protruding laterally beyond the region of the MEMS chip provided with MEMS structures, at least one projection region is removed by separating the projecting material from the carrier material of the MEMS chip. For handling MEMS chips without regions projecting beyond the MEMS structures arranged on a carrier material, for example after post-processing according to the disclosure has been carried out, at least one lateral depression is provided in the carrier material and the MEMS chips are handled by way of a tool engaging in the lateral depression(s).

Claims

1. A method of post-processing of MEMS chips comprising MEMS structures, a carrier material supported by the MEMs structures and a projection region protruding laterally beyond a region defined with MEMS structures, the projection region comprising a projection material, the method comprising: removing the projection region by separating the projecting material from the carrier material.

2. The method of claim 1, wherein removing the projection region comprises creating a continuous gap between the projection region and the carrier material.

3. The method of claim 2, wherein creating the continuous gap comprises removing a sacrificial material in a region of the continuous gap, the sacrificial material being different from the projecting material.

4. The method of claim 3, wherein the sacrificial material is removed by an etching process.

5. The method of claim 2, wherein creating the continuous gap comprises removing material without residues.

6. The method of claim 1, wherein removing the projection region comprises creating a predetermined breaking location between the projection region and the carrier material, and subsequently breaking up the predetermined breaking location.

7. The method of claim 6, wherein creating the predetermined breaking location comprises removing a sacrificial material in a region of the breaking location, the sacrificial material being different from the projecting material.

8. The method of claim 7, wherein the sacrificial material is removed by an etching process.

9. The method of claim 6, wherein creating the predetermined breaking location comprises removing material without residues.

10. The method of claim 6, wherein creating the predetermined breaking location comprises weakening material in a region of the breaking location in a targeted manner.

11. The method of claim 10, wherein high energy radiation is used to weaken the material in the region of the breaking location.

12. The method of claim 10, further comprising breaking up the breaking location by introducing shear stress and/or tensile stress.

13. The method of claim 10, further comprising breaking up the breaking location by changing a temperature and/or by introducing a temperature gradient.

14. The method as claimed in any of the preceding claims, characterized in that at least one projection region is configured for attaching a protective cover for the MEMS chip and the protective cover is removed at the same time as the projection region.

15. The method of claim 1, wherein the MEMS chip comprises a MEMS mirror array.

16. The method of claim 1, further comprising: after removing the projecting material, providing lateral depressions in the carrier material; and handling the MEMS chips using a tool engaging in the lateral depressions.

17. The method of claim 16, wherein the depressions lateral comprise first and second lateral depressions, the first lateral depression being in a first side of the carrier material, and the second lateral depression in a second side of the carrier material adjacent the first side of the carrier material.

18. A method for handling of MEMS chips comprising MEMs structures and a carrier supporting the MEMs structures, the MEMS chips being devoid of regions projecting beyond the MEMS structures, the method comprising: providing lateral depressions in the carrier material; and handling the MEMS chips using a tool engaging in the lateral depressions.

19. The method of claim 18, wherein the depressions lateral comprise first and second lateral depressions, the first lateral depression being in a first side of the carrier material, and the second lateral depression in a second side of the carrier material adjacent the first side of the carrier material.

20. The method of claim 18, wherein the carrier comprise laterally arranged markings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Embodiments of the disclosure will now be described by way of example on the basis of embodiments with reference to the accompanying drawings, in which:

[0056] FIG. 1: shows a schematic illustration of a projection exposure apparatus for photolithography comprising produced MEMS mirror arrays according to the disclosure;

[0057] FIGS. 2a-e: show a schematic illustration of methods according to the disclosure for post-processing of MEMS chips;

[0058] FIGS. 3a-d: show a schematic illustration of possible configuration variants of the separating regions from FIG. 2;

[0059] FIGS. 4a, b: show a schematic illustration in regard to introducing high-energy radiation into a separating region in accordance with FIG. 2;

[0060] FIGS. 5a-c: show a schematic illustration in regard to separation of separating regions configured as predetermined breaking locations from FIG. 2;

[0061] FIGS. 6a-c: show a schematic illustration of tools for separating predetermined breaking locations in accordance with FIG. 5;

[0062] FIGS. 7a, b: show a schematic illustration in regard to removing sacrificial material from separating regions in accordance with FIG. 2;

[0063] FIGS. 8a-c: show a schematic illustration in regard to producing MEMS chips with and without projection regions; and

[0064] FIGS. 9a, b: show a schematic illustration in regard to handling MEMS chips without projection regions.

DETAILED DESCRIPTION

[0065] FIG. 1 illustrates a schematic meridional section of a projection exposure apparatus 1 for photolithography. In this case, the projection exposure apparatus 1 comprises an illumination system 10 and a projection system 20.

[0066] An object field 11 in an object plane or reticle plane 12 is illuminated with the aid of the illumination system 10. To this end, the illumination system 10 comprises an exposure radiation source 13, which, in the illustrated exemplary embodiment, emits illumination radiation at least comprising used light in the EUV range, that is to say with a wavelength of between 5 nm and 30 nm for example. The exposure radiation source 13 can be a plasma source, for example an LPP (laser produced plasma) source or a GDPP (gas discharge produced plasma) source. It can also be a synchrotron-based radiation source. The exposure radiation source 13 can also be a free electron laser (FEL).

[0067] The illumination radiation emerging from the exposure radiation source 13 is initially focused in a collector 14. The collector 14 can be a collector with one or with a plurality of ellipsoidal and/or hyperboloidal reflection surfaces. The illumination radiation can be incident on the at least one reflection surface of the collector 14 with grazing incidence (GI), that is to say at angles of incidence of greater than 45, or with normal incidence (NI), that is to say at angles of incidence of less than 45. The collector 14 can be structured and/or coated on the one hand for optimizing its reflectivity for the used radiation and on the other hand for suppressing extraneous light.

[0068] Downstream of the collector 14, the illumination radiation propagates through an intermediate focus in an intermediate focal plane 15. If the illumination system 10 is constructed in a modular design, the intermediate focal plane 15 can be used, in general, for the separationincluding the structural separationof the illumination system 10 into a radiation source module, comprising the exposure radiation source 13 and the collector 14, and the illumination optical unit 16 described below. In the case of a corresponding separation, radiation source module and illumination optical unit 16 then jointly form a modularly constructed illumination system 10.

[0069] The illumination optical unit 16 comprises a deflection mirror 17. The deflection mirror 17 can be a plane deflection mirror or alternatively a mirror with a beam-influencing effect going beyond the pure deflection effect. Alternatively or additionally, the deflection mirror 17 can be embodied as a spectral filter separating a used light wavelength of the illumination radiation from extraneous light having a wavelength that deviates therefrom.

[0070] The deflection mirror 17 is used to deflect the radiation emanating from the exposure radiation source 13 to a first facet mirror 18. Ifas in the present casethe first facet mirror 18 is arranged in a plane of the illumination optical unit 16 which is optically conjugate to the reticle plane 12 as a field plane, this facet mirror is also referred to as a field facet mirror.

[0071] The first facet mirror 18 comprises a multiplicity of micromirrors 18 that are individually pivotable about two mutually perpendicular axes in each case, for the purpose of controllably forming facets which are each optionally configured with an orientation sensor (not depicted here) for determining the orientation of the micromirror 18. The first facet mirror 18 is thus a microelectromechanical system (MEMS system), as also described in DE 10 2008 009 600 A1, for example.

[0072] A second facet mirror 19 is arranged downstream of the first facet mirror 18 in the beam path of the illumination optical unit 16, with the result that this yields a doubly faceted system, the fundamental principle of which is also referred to as a fly's eye integrator. If the second facet mirror 19as in the depicted exemplary embodimentis arranged in a pupil plane of the illumination optical unit 16, it is also referred to as a pupil facet mirror. However, the second facet mirror 19 can also be arranged at a distance from a pupil plane of the illumination optical unit 16, as a result of which a specular reflector arises from the combination of the first and the second facet mirror 18, 19, for example as described in US 2006/0132747 A1, EP 1 614 008 B1 and U.S. Pat. No. 6,573,978.

[0073] Optionally, the second facet mirror 19 is not constructed from pivotable micromirrors, but rather can comprise individual facets formed from one mirror or a manageable number of mirrors which are significantly larger than micromirrors, which facets are either stationary or tiltable only between two defined end positions. It is howeveras illustratedalso possible, in the second facet mirror 19, to provide a microelectromechanical system having a multiplicity of micromirrors 19 that are individually pivotable about two mutually perpendicular axes in each case, each optionally comprising an orientation sensor.

[0074] The individual facets of the first facet mirror 18 are imaged into the object field 11 with the aid of the second facet mirror 19, with this regularly only being approximate imaging. The second facet mirror 19 can be the last beam-shaping mirror or else actually the last mirror for the illumination radiation in the beam path upstream of the object field 11.

[0075] In each case one of the facets of the second facet mirror 19 is assigned to exactly one of the facets of the first facet mirror 18 for the purpose of forming an illumination channel for illuminating the object field 11. This can for example result in illumination according to the Khler principle.

[0076] The facets of the first facet mirror 18 are imaged overlaid on one another by way of a respective assigned facet of the second facet mirror 19, for the purpose of illuminating the object field 11. Here, the illumination of the object field 11 is as homogeneous as possible. It can have a uniformity error of less than 2%. Field uniformity can be achieved by overlaying different illumination channels.

[0077] By selecting the ultimately used illumination channels, which is possible without problems by way of a suitable setting of the micromirrors 18 of the first facet mirror 18, it is still possible to set the intensity distribution in the entrance pupil of the projection system 20 described below. This intensity distribution is also referred to as illumination setting. Incidentally, it may be desirable here to arrange the second facet mirror 19 not exactly in a plane that is optically conjugate to a pupil plane of the projection system 20. For example, the pupil facet mirror 19 can be arranged so as to be tilted relative to a pupil plane of the projection system 20, as is described in DE 10 2017 220 586 A1, for example.

[0078] In the arrangement of the components of the illumination optical unit 16 as illustrated in FIG. 1, however, the second facet mirror 19 is arranged in an area conjugate to the entrance pupil of the projection system 20. Deflection mirror 17 and the two facet mirrors 18, 19 are arranged tilted both vis--vis the object plane 12 and vis--vis one another in each case.

[0079] In an alternative embodiment (not illustrated) of the illumination optical unit 16, a transfer optical unit comprising one or more mirrors can additionally be provided in the beam path between the second facet mirror 19 and the object field 11. The transfer optical unit can for example comprise one or two normal-incidence mirrors (NI mirrors) and/or one or two grazing-incidence mirrors (GI mirrors). Using an additional transfer optical unit, it is possible for example to take account of different poses of the entrance pupil for the tangential and for the sagittal beam path of the projection system 20 described below.

[0080] It is alternatively possible for the deflection mirror 17 illustrated in FIG. 1 to be dispensed with, for which purpose the facet mirrors 18, 19 should then be suitably arranged vis--vis the radiation source 13 and the collector 14.

[0081] The object field 11 in the reticle plane 12 is transferred to the image field 21 in the image plane 22 with the aid of the projection system 20.

[0082] For this purpose, the projection system 20 comprises a plurality of mirrors M.sub.i, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus 1.

[0083] In the example illustrated in FIG. 1, the projection system 20 comprises six mirrors M.sub.1 to M.sub.6. Alternatives with four, eight, ten, twelve or any other number of mirrors M.sub.i are likewise possible. The penultimate mirror M.sub.5 and the last mirror M.sub.6 each have a passage opening for the illumination radiation, as a result of which the illustrated projection system 20 is a doubly obscured optical unit. The projection system 20 has an image-side numerical aperture that is greater than 0.3 and can also be greater than 0.6, and can be for example 0.7 or 0.75.

[0084] The reflection surfaces of the mirrors M.sub.i can be in the form of freeform surfaces without an axis of rotational symmetry. However, the reflection surfaces of the mirrors M.sub.i can alternatively also be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optical unit 16, the mirrors M.sub.i can have highly reflective coatings for the illumination radiation. These reflective coatings can be designed as multilayer coatings, for example with alternating layers of molybdenum and silicon.

[0085] The projection system 20 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 11 and a y-coordinate of the center of the image field 21. This object-image offset in the y-direction can be of approximately the same magnitude as a z-distance between the object plane 12 and the image plane 22.

[0086] For example, the projection system 20 can be designed to be anamorphic, that is to say it has different imaging scales .sub.x, .sub.y in the x- and y-directions for example. The two imaging scales .sub.x, .sub.y of the projection system 20 can be (.sub.x, .sub.y)=(+/0.25, /+0.125). An imaging scale of 0.25 corresponds here to a reduction with a ratio 4:1, while an imaging scale of 0.125 results in a reduction with a ratio of 8:1. A positive sign in the case of the imaging scale means imaging without image inversion; a negative sign means imaging with image inversion.

[0087] Other imaging scales are likewise possible. Imaging scales .sub.x, .sub.y with the same sign and the same absolute magnitude in the x- and y-directions are also possible.

[0088] The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 11 and the image field 21 can be the same or different, depending on the embodiment of the projection system 20. Examples of projection systems 20 with different numbers of such intermediate images in the x-direction and y-direction are known from US 2018/0074303 A1.

[0089] For example, the projection system 20 can comprise a homocentric entrance pupil. The latter can be accessible. However, it can also be inaccessible.

[0090] A reticle 30 (also referred to as mask) arranged in the object field 11 is exposed by the illumination system 10 and transferred by the projection system 20 onto the image plane 21. The reticle 30 is held by a reticle holder 31. The reticle holder 31 is displaceable by way of a reticle displacement drive 32 for example in a scanning direction. In the exemplary embodiment illustrated, the scanning direction runs in the y-direction.

[0091] A structure on the reticle 30 is imaged onto a light-sensitive layer of a wafer 35 arranged in the region of the image field 21 in the image plane 22. The wafer 35 is held by a wafer holder 36. The wafer holder 36 is displaceable by way of a wafer displacement drive 37 for example along the y-direction. The displacement, firstly, of the reticle 30 by way of the reticle displacement drive 32 and, secondly, of the wafer 35 by way of the wafer displacement drive 37 can be implemented so as to be synchronized with one another.

[0092] The projection exposure apparatus 1 illustrated in FIG. 1, or its illumination system 10, the above description of which reflects known technology, includes the first and/or second facet mirror 18, 19 comprising one or more MEMS chips 100 post-processed according to the disclosure (cf. FIGS. 2a-e, inter alia), namely for example MEMS mirror arrays 101. Each of the MEMS chips 100 here has a multiplicity of individual mirrors 103 adjustable independently by in each case two degrees of freedom of rotation as parts of a MEMS structure 102, which are arranged in a two-dimensional grid. Each of the facet mirrors 18, 19 can be formed by a single or a plurality of MEMS chips 100 or MEMS mirror arrays 101 arranged next to one another.

[0093] As is known, corresponding MEMS mirror arrays 101 are produced jointly with a multiplicity of other MEMS mirror arrays 100 or other MEMS chips 100 on a common wafer and are covered with further wafers provided with suitable depressions, such that when the wafer is subsequently divided into individual MEMS mirror arrays 101 or MEMS chips 100, a respective protective cover 106 for each individual MEMS mirror array 100 is maintained.

[0094] FIG. 2a schematically shows a sectional illustration of two examples of MEMS chips 100 or MEMS mirror arrays 101 such as are present in general after a wafer has been divided. In the case of the MEMS chips 100 or MEMS mirror arrays 101, the actual MEMS structure 102i.e. the individual mirrors 103 and also all components used for systematic pivotingis arranged on a carrier material 104.

[0095] In this case, the carrier material 104 extends laterally beyond the region in which the MEMS structures 102 are arranged, and thus forms a projection region 105 composed of projecting material. These projection regions 105 serve for attaching the protective cover 106 extending over the MEMS structures 102. The protective cover 106 can be fixedly connected to the projection regions 105 e.g. with the aid of an adhesive. Other joining methods, such as e.g. an anodic bonding method, are likewise possible for connecting the protective cover 106 to the projection regions 105.

[0096] In the embodiment variant illustrated on the left in FIG. 2a, a separating region 200 has already been formed between the carrier material 104 in the region provided with MEMS structures 102 and the projection regions 105, which separating region will be explained in even greater detail below in association with FIGS. 3a-d. In the embodiment variant illustrated on the right in FIG. 2b, a corresponding separating region 200 is not (yet) provided.

[0097] FIG. 2a likewise illustrates a package substrate 150, on which the MEMS chip 100 or the MEMS mirror array 101 is intended to be arranged or is arranged. In this case, the extent of the package substrate 150 can be adapted to the extent of the region of the carrier material 104 that is provided with MEMS structures 102. However, it is also possible for the package substrate 150 to be significantly larger than the region in question, which is indicated by the dashed parts of the package substrate 150 in FIGS. 2a-e.

[0098] Even though FIGS. 2a-e show that as a matter of principle, it is also possible for the method according to the disclosure to be carried out without the provision of a package substrate 150, i.e. solely with the actual MEMS chip 100. In this case, the step illustrated in FIG. 2b should be skipped and the package substrate 150 should be disregarded in each of the subsequent figures.

[0099] Specifically, FIG. 2b illustrates that the MEMS chip 100 or the MEMS mirror array 101 is fixedly connected to the package substrate 150. If the package substrate 150 extends beyond the region of the carrier material 104 that is provided with MEMS structures 102, the projection regions 105 and optionally the separating region 200 should if possible not be connected to the package substrate 150.

[0100] In a next step, the protective cover 106 can optionally be removed, which is why it is merely illustrated in a dashed manner in FIG. 2c. The protective cover 106 can be removed by way of releasing the adhesive connection between protective cover 106 and projection region 105. If the adhesive used is a thermally decomposable adhesive, e.g. the temperature can be suitably increased at least locally. Other separating methods are also possible, of course. The fact of whether or not the protective cover 106 is to be removed is dependent on the configuration of the already existing separating region 200 (FIG. 2c, on the left) or of the separating region 200 yet to be created subsequently (FIG. 2c, on the right). What is especially relevant here is whether the separating region 200 is to be accessible from the regions covered by the protective cover 106, which will generally be the case especially in the case of an already implemented arrangement on a package substrate 150; if a package substrate 150 is not (yet) present, the separating region 200 is accessible from the side of the carrier material 104 facing away from the MEMS structures 102, and so the protective cover 106 possibly is not removed in the step illustrated in FIG. 2c.

[0101] If the separating region 200 has not yet been formed (FIG. 2c, on the right), this has to be done in the next step (FIG. 2d, on the right). Possibilities concerning the configuration of the separating region 200 will be described in greater detail below in association with FIGS. 3a-d.

[0102] Finally, the projection regions 105 are separated at the separating regions 200 and removed (FIG. 2e). If the protective cover 106 was still fixedly connected to the projection regions 105, projection regions 105 and protective cover 106 can be removed as a unit. Some possible methods for actually removing the projection regions 105 and protective cover 106 will be discussed in association with FIGS. 5a to 7b.

[0103] If the MEMS chip 100 had not already been arranged on a package substrate 150 beforehand, the MEMS chip 100 can be arranged on a package substrate at the latest at this point in time, which will be explained further in association with FIGS. 9a-b.

[0104] FIGS. 3a-d schematically depicts various configurations of separating regions 200 or methods for separating projecting material in projection regions 105.

[0105] In FIG. 3a, the separating region 200 is not especially configured in the initial state (FIG. 3a, on the left). Rather, the carrier material 104 extends over the separating region 200 into the projection region 105. For the purpose of separating the projection region 105, provision is made for creating a continuous gap 201 between projection region 105 and carrier material 104 of the MEMS chip 100 by virtue of the material situated there in the initial state being removed without residues (FIG. 3a, on the right). In this case, removal can be effected for example by high-energy radiation, such as e.g. ion radiation or laser radiation. Possible embodiment variants for this purpose will be described below with reference to FIGS. 4a-b.

[0106] The high-energy radiation can be applied to the separating region 200 from the side of the carrier material 104 that is provided with MEMS structures 102 and/or from the opposite side relative thereto. Once the continuous gap 201 has been completed, the projection region 105 and a protective cover 106 possibly still connected thereto have been directly separated from the carrier material 104 and can be directly removed.

[0107] FIG. 3b shows an alternative procedure for creating a continuous gap 201 between carrier material 104 and projection region 105. Here in the initial state (FIG. 3b, on the left), a sacrificial material 202 that differs both from the carrier material 104 and from the projecting material in the projection region 105 is provided in the separating region 200. The sacrificial material 202 can be introduced into the carrier material 104 for example during the production of the MEMS structures 102 or may have already been introduced at this point in time.

[0108] In order to create a continuous gap 201, it is merely used to remove the sacrificial material 202. In this case, the sacrificial material 202 can be removed for example using an etching process, wherein a suitable selection of sacrificial material 202 and etchants makes it possible to ensure that neither the carrier material nor the MEMS structures 102 incur damage. Alternatively, the sacrificial material 202 can be thermally decomposable and the continuous gap 201 is created by sufficient heating of at least the sacrificial material 202. It goes without saying that it is also possible to remove the sacrificial material 202 using suitable high-energy radiation.

[0109] After the sacrificial material 202 has been completely removed, the continuous gap 201 has been created, as a result of which the projection region 105 and a protective cover 106 possibly still connected thereto have been directly separated from the carrier material 104. Projection region 105 and/or protective cover 106 can then be directly removed.

[0110] In the embodiment variant in accordance with FIG. 3c, a continuous gap 201 (cf. FIGS. 3a, b) is not created, rather a predetermined breaking location 203 is created, in which the material in the separating region 200 is reduced to a thin and easily breakable material bridge 204. The position and the rest of the configuration of the material bridge 204 within the separating region 200 can be chosen as desired, wherein an edge position vis--vis the carrier material 104, such as is illustrated by way of example in FIG. 3c, middle, is desirable since creating it involves processing of the MEMS chip 100 only on one side.

[0111] For creating the predetermined breaking location 203, it is possible to have recourse to the processes described in association with FIG. 3a and FIG. 3b, specifically removing material without residues in the separating region 200 using high-energy radiation or by removing sacrificial material 202 already introduced in this region beforehand. For explanation of these processes, reference is made to the statements above. It is desirable that the material bridge 204 remains in the embodiment variant in accordance with FIG. 3c.

[0112] After the predetermined breaking location 203 has been created, the projection region 105 and a protective cover 106 possibly still connected thereto can be released from the carrier material 104 by breaking up the predetermined breaking location 203 and can subsequently be removed. Variants in regard to breaking up the predetermined breaking location 203 will also be explained with reference to FIGS. 5a to 7b.

[0113] FIG. 3d illustrates a further alternative for creating a predetermined breaking location 203. Proceeding from a separating region 200 beyond which the carrier material 104 extends right into the projection region 105 (FIG. 3d, on the left), material in the region of the predetermined breaking location 203 to be created is weakened in a targeted manner. This is illustrated by weakening regions 205 in FIG. 3d, middle. In this regard, e.g. using suitable radiation, the crystal structure of the carrier material 104 in the weakening regions 205 can be broken down, i.e. e.g. transformed from a mono- and/or polycrystalline structure to an amorphous structure. Moreover, local heating can lead to a reduction of the density in the weakening regions 205 and hence weakening of the material.

[0114] After weakening has been effected, the predetermined breaking location 203 thus created can be broken up, as a result of which the projection region 105 and a protective cap 106 possibly still connected thereto are separated from the carrier material 104 and can be removed.

[0115] In all of the processes described above with reference to FIGS. 3a-d that use high-energy radiation to create a continuous gap 201 or a predetermined breaking location 203, it should be noted that corresponding radiation 300 (cf. FIG. 4a), even if it is strongly focused, has analbeit generally very smallnumerical aperture which can hamper irradiation especially on the side of the carrier material 104 with the MEMS structure 102 arranged thereon. On account of the numerical apertureat least if the angle of incidence for the radiation is fixed at 0, although this is regularly the caseit is virtually impossible, during irradiation of the side of the carrier material 104 with the MEMS structure 102 arranged thereon, to create a continuous gap 201 or a predetermined breaking location 203 directly adjacent to the region of the carrier material 104 that is actually provided with the MEMS structure 102. In a corresponding procedure, the MEMS structure 102 would practically inevitably be hit by the focused radiation 300 and detrimentally affected.

[0116] As an alternative thereto, it is however possibleas depicted schematically in FIG. 4bto use a collimated beam 301 (i.e. a beam having exclusively parallel rays), the beam 301 being limited to the separating region 200 using a suitable shadow mask 302. In this case, the radiation impinging in the separating region 200 has an angle of incidence of 0, such that even during irradiation on the side of the carrier material 104 that is provided with MEMS structures 102, it is possible without residues to remove material directly adjacent to the region of the carrier material 104 provided with MEMS structures 102.

[0117] If a predetermined breaking location 203 has been created in the separating region 200 (cf. FIGS. 3c, d), FIGS. 5a-c schematically depicts three possible ways of breaking up such a predetermined breaking location 203. In this case, the predetermined breaking location 203 has been created or formed in any desired manner, in general.

[0118] In accordance with FIG. 5a, the predetermined breaking location 203 is separated by a shear stress being introduced into the predetermined breaking location 203. Such a shear stress can be attained by opposing forces being applied to the carrier material 104 and the projection region 105. This is indicated by the arrows 90 in FIG. 5a, wherein the orientation of the arrows 90 can also be reversed.

[0119] As an alternative thereto, it is possibleas depicted schematically in FIG. 5afor a predetermined breaking location 203 also to be broken up by a sufficient tensile stress being applied thereto, which is indicated by the arrows 91.

[0120] When breaking up the predetermined breaking location 203 in accordance with FIG. 5a, which is relevant for example to the embodiment variants of predetermined breaking locations 203 in which the material in the separating region 200 is partly weakened (cf. FIG. 3d), a temperature or a temperature gradient is introduced into the predetermined breaking location 203 (indicated by the heating element 92, although a cooling facility can also be provided). Different thermal expansion of weakening regions 205 vis-{grave over ()}-vis the unchanged material can cause the predetermined breaking location to be broken up, for example.

[0121] FIGS. 6a-c shows various variants or tools 400 in respect of how the shear stress already mentioned with reference to FIG. 5a can be introduced into a predetermined breaking location 203.

[0122] In FIG. 6a, it is assumed that the protective cover 106 is still fixedly connected to the projection regions 105, which for their part howeverunlike the carrier material 104 in the region with MEMS structures 102are not connected to the package substrate 150.

[0123] In this case, the tool 400 for breaking up the predetermined breaking location 203 is a suction die 401, which can be fixedly connected to the protective cover 106 by creating a vacuum between the suction die 401 and the protective cover. By pulling on the suction die 401 in a direction away from the package substrate 150 with simultaneous fixing thereof, a shear stress is generated in the predetermined breaking location 203 and can result in the breaking up thereof, whereupon the protective cover 106 and the projection regions 105 fixedly connected thereto can be removed from the MEMS chip 100 by the suction die 401. As an alternative to a suction die 401, a comparable tool 400 can also be fixedly connected to the protective cover 106 by adhesive bonding.

[0124] The tool 400 in FIG. 6b is suitable for example for an application in the case of MEMS chips 100 arranged on a package substrate 150 which does not extend beyond the region of the carrier material 104 provided with MEMS structures 102. The tool 400 is movable jaws 402, which, as shown in FIG. 6b, are positioned adjacent to the package substrate 150. Using vertical movement of the jaws 402, with the package substrate 150 kept fixed, the predetermined breaking locations 203 via which the projection regions 105 bearing against a jaw 402 are connected to the carrier material 104 can be broken up and the separated material can be removed. In this case, it is unimportant whether or not a protective cover 106 is connected to the projection regions 105 at the time of breaking up.

[0125] In FIG. 6c, the tool 400 from FIG. 6b is used again, although here the jaws 402 are positioned over the projection regions 105 in such a way that vertical movement of the jaws 402 in the direction of the package substrate 150 causes the projection regions 105 to be broken away correspondingly in the direction of the package substrate 150 at the respective predetermined breaking location 203. This can reduce the risk of collision between separated material and MEMS structure 102. However, in this embodiment variant, it is desirable for a protective cover 106 possibly present to be removed before the first predetermined breaking location 203 is broken up.

[0126] If a sacrificial material 202 is provided in the separating region 200 (cf. FIGS. 3b, c), which sacrificial material has to be removed for the purpose of creating a continuous gap 201 or a predetermined breaking location 203, this can be done e.g. via an etching process using etching medium, for example using etching gas.

[0127] In order to minimize the volume to be loaded with etching medium and to protect regions remote from the MEMS chip 100 against etching medium, inlet and outlet channels 107 may have been introduced, or may be introduced as desired, into a protective cover 106 still present at this point in time, through which channels an etching medium suitable for dissolving the sacrificial material 202 in the separating region 200 can be introduced and spent etching medium, etc., can also be removed again (cf. FIG. 7a). The detachment of protective cover 106 and projection regions 105 connected thereto after the sacrificial material 202 has been removedregardless of whether a continuous gap 201 or a predetermined breaking location 203 is thereby created - can then take place e.g. in accordance with FIG. 6a.

[0128] FIG. 7b illustrates a variant in which the MEMS chip 100 with or without a protective cover 106 (therefore only illustrated in a dashed manner) is accommodated in a separate etching chamber 450 which encloses the MEMS chip 100 together with a package substrate 150 possibly present oras illustratedbears sealingly against the package substrate 150 and through the in- and outlets 451 of which etching medium is introduced. For example, it is possible in this way also to remove sacrificial material 202 accessible exclusively from the side facing away from the MEMS structures 102 in the separating regions 200. With respect to ultimately removing the projection regions 105 and/or the protective cover 106, optionally including breaking up a created predetermined breaking location, reference is made to the explanations above.

[0129] Even if projection regions 105 present can be removed by the above-described method for post-processing of MEMS chips 100, projection regions 105 can be reduced or even entirely avoided as early as during the production of corresponding MEMS chips 100, as a result of which the outlay for corresponding post-processing can also be reduced or completely obviated.

[0130] FIG. 8a schematically depicts typical production of MEMS chips 100: A plurality of groups of MEMS structures 102 are created on a wafer 500, each group later forming the MEMS structures 102 of an individual MEMS chip 100 (FIG. 8a, on the left). A respective clearance 501 is provided between the groups of MEMS structures 102 andas knowncan be used e.g. to connect a wafer having depressions (not illustrated) to the illustrated wafer 500 in order in this way to be able to create protective covers 106 for the MEMS chips 100 after the separation of the wafer 500 centrally through the clearances. The situation after the wafer 500 has been divided in such a way is illustrated in FIG. 8a, on the right. After the separation of the wafer 500, each MEMS chip 100 has a circumferential projection region 105, to which for example individual protective covers 106 can be secured (cf. FIGS. 2a-e).

[0131] In order to facilitate the removal of the projection regions 105, provision can be made, when dividing the wafer 500 or at a later point in time, for subdividing the projection regions 105 into individual sections by creating gaps or weakened regions 502, which sections can in general also be removed individually.

[0132] Especially if no protective cover 106 is used during the further handling of the MEMS chips 100, the MEMS structures 102 can be arranged in each case in pairs adjacently in one direction in a manner directly adjoining one another on the wafer 500 (FIG. 8b, on the left). After dividing the wafer 500, this then results in individual MEMS chips 100 in which the projection regions 105 are no longer present circumferentially (cf. FIG. 8a, on the right), but rather only on two of the four sides of each MEMS chip 100 (FIG. 8b, on the right). The outlay for post-processing, namely for removing the residual projection regions 105, accordingly decreases. Here, too, the projection regions 105 can be suitably subdivided into sections that can be removed individually.

[0133] As an alternative thereto, it is also possible, of course, to arrange the MEMS structures 102 completely without a clearance 501 (cf. FIGS. 8a, b) on the wafer 500 (cf. FIG. 8c, on the left), such that dividing the wafer 500 directly results in MEMS chips 100 without any projection regions 105 (FIG. 8c, on the right). In this case, dividing the wafer 500 can be realized by any known processes. For example, it is also possible to carry out the dividing by suitably removing carrier material in the course of the production of the MEMS structure. In this case, a process known from the production of MEMS structures for selective removal of materiale.g. an etching processcan be directly applied to the carrier material in order thus to achieve the dividing. Such an etching process can be provided as a separate step in the course of the production of the MEMS structures. However, it is also possible to effect concomitant removal in a method step provided for producing MEMS structures.

[0134] If MEMS chips 100 without any projection regions 105 are availableirrespective of whether they have been freed of originally present projection regions 105 by a post-processing method according to the disclosure (cf. FIGS. 2a to 7b) or have already been manufactured without projection regions 105 (cf. FIG. 8c)they can be arranged, if this has not yet been done, at a very small distance from one another on a package substrate 150, as is depicted schematically in FIG. 9a.

[0135] For handling of the MEMS chips 100, a tool 600 is provided and enables the individual MEMS chips 100 to be gripped on two adjacent sides of the carrier material 104, such that the MEMS chips 100 can be arranged with the other two sides of the carrier material 104 directly adjacent to MEMS chips 100 already arranged on the package substrate 150. The tool 600 and its interplay with a MEMS chip 100 is shown in two plan views and two associated partial sectional views in FIG. 9b, wherein the right-hand illustrations each show the tool 600 in engagement, while the tool 600 is still separated from the MEMS chip 100 in the left-hand illustrations.

[0136] In order that the MEMS chips 100 can be gripped securely and precisely by the tool 600, the MEMS chips 100 have lateral depressions 108 in the region of the carrier material 104, into which depressions corresponding projections 601 on the tool 600, which for the rest is configured like tongs, can engage in a positively locking manner.

[0137] In addition to the two depressions 108, from which the orientation of the MEMS structures of the MEMS chip vis--vis the carrier material also be read.

[0138] If depressions for engagement of a handling tool 600 are provided only on two adjacent sides of the carrier material, but at least one side of the carrier material is depression-free, the orientation of the MEMS structures 102 of the MEMS chip 100 vis--vis the carrier material 104 can be read from the arrangement of the depressions, as a result of which the correct alignment of each MEMS chip 100 can be ensured during the integration thereof. On the carrier material 100, provision can be made of even further depressions in a form and arrangement comparable to a barcode as marking 109, in which batch or serial numbers of the respective MEMS chip 100 are stored.

[0139] The depressions 108 and also the marking 109 can be integrated into the carrier material 104 during the production of the MEMS chip 100. For example, the regions in question, which are regularly internal regions at least temporarily, can firstly be filled with sacrificial material corresponding to a sacrificial material 202 in the separating region 200, which material can be removed in the course of the removal of the sacrificial material 202 in the separating region 200.