Method for manufacturing passive optical components, and devices comprising the same

Abstract

A device comprises at least one optics member (O) comprising at least one transparent portion (t) and at least one blocking portion (b). The at least one transparent portion (t) is made of one or more materials substantially transparent for light of at least a specific spectral range, referred to as transparent materials, and the at least one blocking portion (b) is made of one or more materials substantially non-transparent for light of the specific spectral range, referred to as non-transparent materials. The transparent portion (t) comprises at least one passive optical component (L). The at least one passive optical component (L) comprises a transparent element (6) having two opposing approximately flat surfaces substantially perpendicular to a vertical direction in a distance approximately equal to a thickness of the at least one blocking portion (b) measured along the vertical direction, and, attached to the transparent element (6), at least one optical structure (5).

Claims

1. A method for manufacturing a device comprising at least one passive optical component, said method comprising: providing a wafer comprising at least one blocking portion and a multitude of transparent elements; wherein each of said multitude of transparent elements is made of one or more transparent materials substantially transparent for light of at least a specific spectral range, and said at least one blocking portion is made of one or more non-transparent materials substantially non-transparent for light of said specific spectral range; wherein one or more of the following applies for the wafer: (A) a vertical extension of each of said multitude of transparent elements is the same as a vertical extension of said at least one blocking portion; (B) the at least one blocking portion together with the transparent elements describes a solid plate-like shape with opposing flat surfaces; (C) the wafer has an extension in a first direction, which is small with respect to the wafer's extension in another two directions that are perpendicular to the first direction, wherein each of the transparent elements has two opposing flat surfaces perpendicular to the first direction, wherein the two opposing flat surfaces are arranged in a distance equal to a thickness of said at least one blocking portion measured along the first direction.

2. The method according to claim 1 comprising: manufacturing an optics wafer, comprising a multitude of passive optical components including said at least one passive optical component; wherein manufacturing a wafer comprises: producing said multitude of passive optical components by producing on each of said multitude of transparent elements at least one optical structure.

3. The method according to claim 2, wherein said at least one optical structure comprises at least one lens element.

4. The method according to claim 2, said producing said multitude of optical structures is carried out using replication.

5. The method according to claim 4, wherein said producing said optical structures using replication comprises: applying a replication material to each of said multitude of transparent elements; replicating a structured surface in said replication material; hardening said replication material; removing said structured surface.

6. The method according to claim 2 comprising: preparing a wafer stack comprising said optics wafer and at least one additional wafer; obtaining a multitude of separate modules each comprising at least one of said multitude of passive optical components, by separating said wafer stack.

7. The method according to claim 1 comprising: manufacturing said wafer; wherein manufacturing the wafer comprises: providing a precursor wafer substantially made of said non-transparent material having openings in places where said transparent elements are supposed to be located; at least partially filling said openings with at least one of said transparent materials.

8. The method according to claim 7, wherein at least partially filling said openings with at least one of said transparent materials is carried out using a dispenser.

9. The method according to claim 7 comprising manufacturing said precursor wafer using replication.

10. The method according to claim 1, wherein each of the transparent elements has two opposing flat surfaces perpendicular to the first direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, examples of the invention are described in more detail with reference to the drawings. The figures show schematically:

(2) FIG. 1 a diagrammatical illustration of a cross-section through a device being a passive optical component;

(3) FIG. 2 a diagrammatical illustration of a top view of the device of FIG. 1;

(4) FIG. 3 a diagrammatical illustration of a manufacturing step in a cross-sectional view;

(5) FIG. 4 a diagrammatical illustration of a manufacturing step in a cross-sectional view;

(6) FIG. 5 a diagrammatical illustration of a manufacturing step in a cross-sectional view;

(7) FIG. 6 a diagrammatical illustration of a cross-section through a device being an optics wafer;

(8) FIG. 7 a diagrammatical illustration of a cross-section through a device being an optics wafer;

(9) FIG. 8 a diagrammatical illustration of a cross-section illustrating a manufacturing step;

(10) FIG. 9 a diagrammatical illustration of a cross-section illustrating a manufacturing step;

(11) FIG. 10 a diagrammatical illustration of a detail of a cross-sectional view;

(12) FIG. 11 a diagrammatical illustration of a detail of a cross-sectional view;

(13) FIG. 12 a diagrammatical illustration of a cross-section through a device being an opto-electronic module illustrating a device being an electronic device;

(14) FIG. 13 a cross-sectional view of wafers for forming a wafer stack for manufacturing a multitude of modules of FIG. 12;

(15) FIG. 14 a cross-sectional view of a device being a wafer stack for manufacturing a multitude of modules of FIG. 12;

(16) FIG. 15 a diagrammatical illustration of a cross-section through a device being a semi-finished part;

(17) FIG. 16 a diagrammatical illustration of a cross-section through a device being a semi-finished part.

(18) The reference symbols used in the figures and their meaning are summarized in the list of reference symbols. The described embodiments are intended as examples.

DETAILED DESCRIPTION

(19) FIG. 1 is a schematized diagrammatical illustration of a cross-section through a device being a passive optical component O. FIG. 2 is a schematized diagrammatical illustration of a top view of the device of FIG. 1. Passive optical component O can and will also be referred to as optics member O.

(20) In FIG. 1, the vertical (z) direction is indicated, as well as the x direction. The directions indicated in FIG. 2 (directions in the x-y plane) are referred to as lateral directions.

(21) Optics member O comprises a blocking portion b and two transparent portions t. In fact: Optics member O consists of a blocking portion b and two transparent portions t. Blocking portion b is made of a material, for example, a polymer material, which is substantially non-transparent for light of a specific spectral range (wavelength or wavelength range), whereas the transparent portions t are made of a material which is substantially transparent for light at least of the specific spectral range. This way, blocking portion b functions as an aperture for each of the transparent portions t and also fixes (or holds) the transparent portions t. And, as will become clearer later (cf. FIG. 12), blocking area b can function as a shield for protection from undesired light, by substantially attenuating or blocking light of the specific spectral range.

(22) Each of the transparent portions t comprises at least two parts; in the example of FIGS. 1 and 2, it is three parts: Two lens elements 5 (or, more generally: optical structures 5) and a transparent element 6. Together, these form a lens member L (or, more generally: a passive optical component). Optical structures 5 protrude from the surface described by the blocking portion b; in other words, they extend vertically beyond the level described by the blocking portion b. When the optical structures 5 are lens elements (e.g., concave ones or, as shown in FIG. 1, convex ones) having at least one apex, these apices are located outside a vertical cross-section of the optics member O (FIG. 1).

(23) Blocking portion b together with transparent elements 6 describes a (close-to-perfect) solid plate-like shape. The optical structures 5 protrude therefrom. Each of the transparent elements 6 has two opposing lateral surfaces which are substantially flat, i.e. two surfaces lying substantially in the x-y plane.

(24) The outer shape of optics member O is generally plate- or disk-like, with rectangular side walls.

(25) Particularly interesting is the manufacturability of the optics members O and of other devices according to the invention. In particular, wafer-level manufacturing is possible. This will be explained referring to FIGS. 3 to 14.

(26) FIGS. 3 to 7 are schematized diagrammatical illustrations of manufacturing steps, in a cross-sectional view. FIG. 3 illustrates schematically a precursor wafer 8 made of non-transparent material, having a multitude of holes or openings 11. One or more of these are arranged, for example, on a rectangular lattice; since optics member O of FIGS. 1 and 2 to be manufactured comprises two transparent portions t, these two are arranged on a rectangular lattice.

(27) Precursor wafer 8 can be manufactured by replication, e.g., using embossing or molding. Or a blank wafer can be provided with the openings 11 by drilling or etching.

(28) It is to be noted that the shape of the openings 11 in precursor wafer 8 can of course be different from the cylindrical shape shown in FIGS. 1 to 3. The holes 11 need not be prismatic having a vertical axis, and a lateral cross-section does not have to be circular. E.g., elliptic shapes are possible; and the shape in a lateral cross-section may vary along the vertical direction; and the area described by the holes 11 in a lateral cross-section may vary along the vertical direction.

(29) In a next step (cf. FIG. 4), the transparent elements 6 are formed by filling the openings 11 with a suitable transparent material T. During the filling, the transparent material T, for example, a polymer, is liquid or viscous. A squeegee process similar to what is known from screen printing can be used, or a dispenser, e.g., like known from semiconductor industry and used for underfilling, can be used. The dispensing can be carried out one-by-one, or several openings are simultaneously filled, e.g., by using several hollow needles outputting transparent material T.

(30) During the filling, the precursor wafer 8 lies on a support layer 12, e.g., made of a silicone such as polydimethylsiloxane. Support layer 12 is supported by a rigid support substrate 13, e.g., a glass plate, for mechanical stability.

(31) During filling-in the transparent material. T, care has to be taken order to prevent the formation of air bubbles or cavities in the material T, because this would likely degrade the optical properties of the passive optical components L to be produced, since transparent element 6 is a constituent thereof. E.g., one can early out the dispensing in such a way that wetting of the wafer material starts at an edge formed by the precursor wafer 8 and the underlying support layer 12 or in a place close to such an edge; e.g., by suitably guiding a hollow needle outputting the material T close to such an edge. This is visualized in FIGS. 8 and 9 which are schematized diagrammatical illustrations of a cross-section for illustrating this manufacturing step. Depending on properties of the involved materials, more particularly of the surface tensions of transparent material T, of the material of precursor wafer 8 and of the material of support layer 12, the shapes described by the material T while being filled in into the holes 11 can vary and possibly look similar to what is schematically illustrated in FIG. 8 and in FIG. 9, respectively. The dashed lines indicate the time evolvement of the shape with increasing amount of filled-in material T, FIGS. 8 and 9 illustrating different behavior for different wetting angles.

(32) The filling-in is stopped when enough material T is filled in. Before proceeding, the filled-in transparent material T is hardened, e.g., by curing it, e.g., using heat or UV radiation. It is possible, that the so-obtained transparent elements have two (nearly) perfectly planar lateral surfaces, in particular (nearly) perfectly forming a common planar surface with the surrounding (blocking) portion of the precursor wafer 8. But possibly, the filling, accomplished using a squeegee or by dispensing or accomplished differently, may be less perfect. Examples therefor are shown in FIGS. 10 and 11, which are schematized diagrammatical illustrations of a detail of a cross-sectional view. E.g., a concave surface might be formed as illustrated in FIG. 10, or a convex surface might be formed as illustrated in FIG. 11. In the convex case, it can be advantageous to provide a polishing step before continuing with the next manufacturing steps. By means of the polishing, it is possible to achieve that the protruding portion is taken down at least partially. In addition, it is possible that polishing can remove spilled-over transparent material, i.e. material which has not been deposited in the desired location during filling-in, e.g., material that has not been deposited on a transparent element, but, e.g., slightly next thereto.

(33) It is alternatively also possible to accomplish the formation of the transparent elements 6 in a different fashion involving finishing steps or not. By means of the support layer 12, it can be possible to ensure a rather planar surface of the transparent material T at that side of the wafer, but other ways of accomplishing this might also be used.

(34) When each of the openings 11 contains an appropriate amount of hardened transparent material T, optical structures 5 are applied thereto (cf. FIGS. 5 and 6). This can be accomplished, e.g., by replication, in a way known in the art, e.g., as described in WO 2005/083789 A2 or in US 2011/0050979 A1. E.g., in a form having a structured surface describing a negative of the optical structures 5 to be produced, a suitable amount of a replication material provided, and then, the form with the structured surface is moved towards the wafer, so as to get the replication material in an appropriate contact with a transparent element 6. Subsequently, the replication material is hardened, e.g., cured, e.g., by heating or irradiating with light (such as UV light), and the form is removed. The formation of the optical structures 5 (by replication or differently) may be accomplished one-by-one or several at a time (but only a fraction of all on one side of the wafer), or simultaneously for all on one side of the wafer.

(35) The optical structures 5 can be formed on one or on both sides of the wafer (cf. FIGS. 5 and 6). The lateral extension of the optical structures 5 can be larger or smaller than the lateral extension of the transparent elements 6, or substantially be identical, as shown in FIGS. 5 and 6. The optical structures 5 can be lens elements of virtually any shape, be it refractive and/or diffractive lens elements, or prism elements or others. For many applications, lens elements are a suitable choice.

(36) The so-obtained optics wafer OW (cf. FIG. 6) can be a device itself and can be used, e.g., for producing further products.

(37) It is also possible to separate such an optics wafer OW into a multitude of optics member like those shown in FIGS. 1 and 2, e.g., by dicing. In FIG. 7 showing a schematized diagrammatical illustration of a cross-section through a device being an optics wafer OW, the thin dashed rectangles indicate where separation can take place.

(38) FIG. 12 is a schematized diagrammatical illustration of a cross-section through a device being an opto-electronic module 1 also illustrating a device being an electronic device 10 comprising such an opto-electronic module 1 mounted on a printed circuit board 9 of the electronic device 10. The electronic device 10 can be, e.g., a hand-held electronic communication device such as a smart phone, or a photographic device such as a photo camera or a video camera.

(39) The opto-electronic module 1 comprises an optics member O as shown in FIGS. 1 and 2 and also at least one active optical component such as a detector D (e.g., a photo diode) and a light emitter E (e.g., a light-emitting diode). The active optical components D, E are mounted on a substrate P provided with solder balls 7. Between substrate P and optics member O, a separation member S (or spacer member S) with openings 4 is arranged, i.a. for ensuring a suitable distance between the active optical components D, E and the passive optical components L. On top, a baffle member B having transparent regions 3 is arranged functioning as a baffle.

(40) The substrate P, the optics member O, the baffle member B and the separating member S are of generally block- or plate-like shape (wherein at least the separating member S and the baffle member B have at least one hole each). This way, it is possible that a particularly good manufacturability is achieved.

(41) There exists a specific wavelength range for which the passive optical components L and thus the transparent material T and the material of which the optical structures 5 are made (which may be identical with or different from material T) are transparent, but for which the material of which the blocking portion b is made is non-transparent.

(42) There is, e.g., if the opto-electronic module 1 is a proximity sensor, an overlapping wavelength range of the wavelength range of light emittable by light emitter E and the wavelength range of light detectable by the light detector D. At least in that overlapping wavelength range, blocking portion b will be non-transparent, and at least in a portion of the overlapping wavelength range, transparent portion t will be transparent. Note that the term wavelength range does not imply that it is contiguous. The overlapping wavelength range can be in the infrared portion and more specifically in the near-infrared portion of the electromagnetic spectrum. This can be particularly useful for proximity sensor.

(43) An opto-electronic module 1 as shown in FIG. 12 can well be manufactured on wafer-scale. Therein, optics wafers like shown in FIG. 6 can be used.

(44) FIG. 13 is a schematized cross-sectional view of wafers for forming a wafer stack 2 (cf. FIG. 14) for manufacturing a multitude of modules 1 of FIG. 12.

(45) Four wafers are sufficient for manufacturing a multitude of modules 1 as shown in FIG. 12: A substrate wafer PW, a spacer wafer SW, an optics wafer OW (like shown in FIG. 6) and a baffle wafer BW. Each wafer comprises a multitude of the corresponding members comprised in the corresponding module 1 (cf FIG. 12), arranged, for example, on a rectangular lattice, e.g., with a little distance from each other for a wafer separation step.

(46) Substrate wafer PW can be a printed circuit board (PCB) of standard PCB materials, provided with solder balls 7 on the one side and with active optical components (E and D) soldered to the other side. The latter can be placed on substrate wafer PW by pick-and-place using standard pick-and-place machines.

(47) Ways of manufacturing optics wafer OW have been described above.

(48) In order to provide maximum protection from detecting undesired light, all wafers PW, SW, OW, BW can substantially be made of a material substantially non-transparent for light detectable by detecting members D, of course except for transparent portions t and transparent regions 3.

(49) Wafers SW and BW and possibly also all or a portion of wafer OW can be produced by replication. In an exemplary replication process which can also be used for manufacturing precursor wafer 8 or transparent elements 6, a structured surface is embossed into a liquid, viscous or plastically deformable material, then the material is hardened, e.g., by curing using ultraviolet radiation or heating, and then the structured surface is removed. Thus, a replica (which in this case is a negative replica) of the structured surface is obtained. Suitable materials for replication are, e.g., hardenable (more particularly curable) polymer materials or other replication materials, i.e. materials which are transformable in a hardening step (more particularly in a curing step) from a liquid, viscous or plastically deformable state into a solid state. Replication is a known technique, cf., e.g., WO 2005/083789 A2 or US 2011/0050979 A1 for more details about this.

(50) FIG. 14 is a schematized cross-sectional view of a device being a wafer stack 2 for manufacturing a multitude of modules 1 of FIG. 12.

(51) In order to form a wafer stack 2, the wafers BW, OW, SW, PW are aligned and glued together, e.g., using a heat-curable epoxy resin. The aligning comprises aligning the substrate wafer PW and the optics wafer OW such that each of the detecting members D is aligned with respect to at least one of the transparent portions t, in particular wherein each of the detecting members D is aligned in the same way to one of the transparent portions t each, and the same applies to the light emitters E.

(52) The thin dashed rectangles indicate where separation takes place, e.g., by means of a dicing saw.

(53) Although FIGS. 3 to 7 and 13 and 14 only show provisions for three modules 1, there can be in one wafer stack provisions for at least 10, rather at least 30 or even more than 50 modules in each lateral direction.

(54) It is to be noted that it is possible to think of devices which comprise an optics member O, wherein the optics member is not comprised in an opto-electronic module 1.

(55) It is further to be noted that the passive optical components L obtained in a manner described above are not unitary parts. They comprise at least two, e.g., two or three constituents, namely transparent element 6 and optical structures 5 attached thereto. Transparent element 6, however, can be a unitary part.

(56) A semi-finished part (which can in a certain view also be a device according to the invention) obtained by providing the transparent elements 6 in a precursor wafer 8 can be a flat disk-like wafer having no holes penetrating the wafer (or at least no holes penetrating the wafer in the regions where the transparent portions t are).

(57) The semi-finished part can have virtually no or only shallow surface corrugations in those regions, wherein such surface corrugations, if present, can be, for example, concave (cf. FIG. 10), i.e. do not extend beyond the wafer surface as described by the at least one blocking portion b. Convex meniscuses possibly formed can be flattened, e.g., as described above, by polishing, so as to obtain a transparent element 6 having parallel surfaces adjusted to the wafer thickness, wherein possibly also the wafer thickness can be adjusted (reduced).

(58) But: The semi-finished part can alternatively have a structured surface, on one or on both sides, in particular in those regions where the transparent portions t are. There can be wanted corrugations in blocking portion b. In particular, it is possible that a wafer, a combined optics wafer, is provided which is a combination of an optics wafer (such as the described optics wafer OW) and a spacer wafer (such as the described spacer wafer SW). Accordingly, then, the spacer wafer is optional, its properties and functions are fulfilled by an optics wafer (combined optics wafer) structured and configured accordingly. This can be accomplished, e.g., by manufacturing as a unitary part: what is described above as spacer wafer SW and what is described above as at least one blocking portion b. A corresponding optics wafer (combined optics wafer) can be readily visualized when looking upon wafers OW and SW in FIG. 14 as one single part. Starting from a suitable semi-finished part, a combined semi-finished part, a combined optics wafer can be obtained by producing thereon (on transparent portions of the combined semi-finished part) optical structures, e.g., in a way as described above, e.g., by dispensing.

(59) Another example of a combined semi-finished part (referenced ow) is illustrated in FIG. 16, whereas a semi-finished part ow which more closely corresponds to what is described in conjunction with FIGS. 3 to 7 and 12 to 14 is illustrated in FIG. 15.

(60) Furthermore an optics wafer (combined optics wafer) can be provided which is a combination of an optics wafer (such as the described optics wafer OW) and a baffle wafer (such as the described baffle wafer BW). Accordingly, then, the baffle wafer is optional, its properties and functions are fulfilled by an optics wafer (combined optics wafer) which is structured and configured accordingly. This can be accomplished, e.g., by manufacturing as a unitary part: what is described above as baffle wafer BW and what is described above as at least one blocking portion b. A corresponding optics wafer can be readily visualized when looking upon wafers OW and BW in FIG. 14 as one single part. A suitable combined semi-finished part might look similar to what is shown in FIG. 16.

(61) Of course, it is also possible that both sides of an optics wafer (combined optics wafer) are structured. E.g., so as to make, in the embodiment of FIG. 14, baffle wafer BW and spacer wafer SW obsolete.

(62) Filling-in of transparent material T into a single- or both-sidedly structured precursor wafer for forming the transparent elements 6 (for obtaining a semi-finished part) can be accomplished similarly to what is shown in FIG. 4 (and what is implied in FIG. 16 by the support layer 12), wherein in FIG. 16, a not-structured side of combined semi-finished part ow faces the support layer 12. Alternatively, a structured support layer 12 could be used during forming the transparent elements 6, for avoiding a (too intense) flowing-through of filled-in material through the openings of the precursor wafer. The latter way of proceeding can be particularly useful when a precursor wafer having a structured surface on both sides shall be provided with the transparent elements 6.

(63) Corresponding to what has just been described for wafers, a combined optics member can also be provided. The blocking portion of an optics member can have a structured surface, in particular a surface with protruding portions protruding vertically beyond a surface of a transparent element of the combined optics member. It is possible that a member (combined optics member) is provided which is a combination of the above-described optics member and the above-described separation member (or a combination of the described optics member and the described baffle member, or a combination of all three). Accordingly, then, the separation member (and/or the baffle member) is optional, its properties and functions are fulfilled by an optics member which is structured and configured accordingly. This can be accomplished, e.g., by manufacturing as a unitary part: what is described above as separation member S (and/or what is described above as baffle member B) and what is described above as at least one blocking portion b.

(64) A usual consequence of providing such a combined optics member or combined optics wafer is that the number of parts (of an item to be constructed, such as of a module 1) and the number of assembly steps is reduced, and less aligning errors will usually occur.

(65) Coming back to FIG. 15, the semi-finished part ow shown there can be subjected to a polishing step on one or on both sides. The polishing step can be accomplished, e.g., for thinning the wafer ow (precisely) to a desired thickness, and/or for improving the optical properties (at least of the transparent elements 6). Of course, also a one-sidedly structured semi-finished part can be polished, at least on its flat (not-structured) side.

(66) Furthermore, it is to be noted that it is possible to polish precursor wafers, on one or both sides, at least on at least one flat side. Doing so not only possibly contributes to a flatter and/or more even surface of the precursor wafer, but may allow to reduce the thickness of the precursor wafer to a desired thickness, which may be helpful in possible subsequent manufacturing steps.

(67) If a semi-finished part (combined or not) is itself a device and shall be used without producing optical structures on the transparent elements 6, it can be useful to polish one or both sides, for achieving an optical grade surface, in particular a surface being particularly plane and having a particularly small surface roughness.

(68) When, for obtaining an optics wafer, optical structures 5 are applied (e.g., by means of replication) to a semi-finished part, where concave meniscuses of the transparent material T are present, the replication can take place on these meniscuses, wherein the amount of applied replication material might have to be adjusted accordingly. If a corresponding semi-finished part is polished, well-defined flat surfaces can be obtained, and less variation is provided for subsequent replication steps. Thus, replication is likely to be carried out easier and/or can lead to a more stable (and reproduceable) process and to a possibly better precision.

(69) The materials which are hardened, for example, cured, during a manufacturing process described anywhere above can be polymer-based materials such as epoxy resins.

(70) Due to manufacturing on wafer-level, most alignment steps are carried out on wafer-level making it possible to achieve a very good alignment (in particular of members D and E with respect to passive optical component L) in a rather simple and very fast way. The overall manufacturing process is very fast and precise. Due to the wafer-scale manufacturing, only a very small number of production steps is required for manufacturing a multitude of modules 1 and/or a multitude of optics members O.

(71) The optics member O (and also the other addressed devices) can be useful in many applications, in particular where apertures are applied and/or where protection from light is sought, and/or where mass production is necessary and/or where particularly small optical members (or passive optical components) are needed.

(72) Other implementations are within the scope of the claims.

LIST OF REFERENCE SYMBOLS

(73) 1 device, opto-electronic module 2 device, wafer stack 3 transparent region 4 opening 5 optical structure, lens element 6 transparent element 7 solder ball 8 precursor wafer 9 printed circuit board 10 device, electronic device, smart phone 11 hole, opening 12 support layer 13 support substrate b blocking portion, non-transparent portion B baffle member BW baffle wafer D detector, light detector, photo diode E light emitter, light-emitting diode L passive optical component, lens member O device, optics member ow device, semi-finished part ow device, semi-finished part, combined semi-finished part OW device, optics wafer P substrate PW substrate wafer S separation member SW spacer wafer t transparent portion T transparent material