Method for conditioning a replication tool and related method for manufacturing a multitude of devices

Abstract

The method for manufacturing a multitude of devices comprises: providing a replication tool comprising a tool material; conditioning the replication tool, wherein the conditioning comprises applying a treatment to the tool material, wherein the treatment comprises exposing the tool material to a conditioning material. And it further comprises, after the conditioning: carrying out one or more replication processes, wherein in each of the one or more replication processes, one or more of the devices are produced from a replication material by replication using the replication tool. The treatment can comprise dimensionally changing the tool material by the exposure of the tool material to the conditioning material. Before carrying out the replication processes, the conditioning material can be hardened and removed.

Claims

1. A method for manufacturing a multitude of devices, the method comprising: providing a replication tool comprising a tool material; conditioning the replication tool, wherein conditioning the replication tool includes applying a treatment to the tool material, the treatment including exposing the tool material to a conditioning material, the treatment further including dimensionally changing the tool material by uptake of the conditioning material in the tool material; the method further comprising, after the conditioning: carrying out one or more replication processes, wherein in each of the one or more replication processes, one or more of the devices are produced from a replication material by replication using the replication tool.

2. The method according to claim 1, wherein both, the replication material and the conditioning material, are materials which are liquid in an initial state and which can be transformed into a hardened state by exposure to energy.

3. The method according to claim 1, wherein the replication material is a liquid epoxy resin and the conditioning material is a liquid epoxy resin.

4. The method according to claim 1, wherein the replication material and the conditioning material are the same material.

5. The method according to claim 1, wherein the tool material is exposed to the conditioning material for a first time duration, and wherein in each of the one or more replication processes, the tool material is exposed to the replication material for a respective second time duration before hardening the replication material and removing the replication material from the replication tool, and wherein the first time duration exceeds each of the second time durations.

6. The method according to claim 1, wherein at least two replication processes are carried out, and wherein during the conditioning of the replication tool, the tool material is exposed to the conditioning material for a time duration t1 and subsequently retained for a time duration t2 with the conditioning material removed from the tool material, and wherein during each of the replication processes, the tool material is exposed to the replication material for a respective time duration referred to as exposure time and subsequently retained for a time duration referred to as retaining time, and wherein a target parameter is defined for the devices.

7. The method according to claim 6, wherein values for the time durations t1 and t2 and for the exposure times and the retaining times satisfy the condition that for the devices produced in the replication processes, a mean deviation of target parameter values from a mean value of the target parameter values is at most 70%, of a deviation from said mean value of the target parameter values of the devices produced in the replication processes, of a mean value of target parameter values of devices produced by hardening the conditioning material at the end of time duration t1.

8. The method according to claim 6, wherein a target value of the target parameter is defined for the devices, and wherein values for the time durations t1 and t2 and for the exposure times and the retaining times fulfill the condition that a mean deviation from the target value of target parameter values of the devices produced in the replication processes is smaller than a mean deviation from the target value of the target parameter values of devices produced by hardening the conditioning material at the end of time duration t1.

9. The method according to claim 6, wherein a target value of the target parameter is defined for the devices, and wherein an acceptance band around the target value is defined for the devices, and wherein the acceptance band has a width, and wherein values of the time durations t1 and t2 and of the exposure times and the retaining times fulfill the condition that a mean value of the target parameter of the devices produced in each the replication processes lies within the acceptance band.

10. The method according to claim 6, wherein the times t1 and t2 and the exposure times and the retaining times are determined before carrying out the replication processes.

11. The method according to claim 1, wherein the devices are either: optical devices; or passive optical components.

12. The method according to claim 1, wherein the tool material has an open porous structure and, optionally, wherein the treatment comprises letting the conditioning material permeate into the tool material.

13. The method according to claim 1, wherein the tool comprises one or more replication sites, the tool material establishing a replication surface in each of the one or more replication sites, and wherein the treatment comprises applying the conditioning material to each of the replication surfaces.

14. The method according to claim 1, wherein the treatment comprises exposing the tool material to the conditioning material for a time duration which is at least half as long as a time duration required for achieving a saturation of the tool material with the conditioning material.

15. The method according to claim 1, wherein the tool material is interspersed with one or more of pores and channels, wherein a portion of a fluid present in at least a portion of the pores and channels, respectively, prior to the treatment is replaced by the treatment by a portion of the conditioning material.

16. The method according to claim 1, wherein the tool material is a resilient material.

17. The method according to claim 1, comprising terminating the exposure of the tool material to the conditioning material by removing the conditioning material from the replication tool.

18. The method according to claim 1, wherein the conditioning material is a material which is liquid or plastically deformable in an initial state and which can be transformed into a hardened state by exposure to energy, and wherein during the exposure of the tool material to the conditioning material, the conditioning material is in its initial state.

19. The method according to claim 18, wherein the treatment comprises transforming the conditioning material into its hardened state and removing the hardened conditioning material from the replication tool.

20. The method according to claim 1, comprising, subsequent to the exposing of the tool material to the conditioning material, retaining the replication tool for another time duration, wherein said other time duration is terminated by an exposure of the replication material to a replication material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention is described in more detail by means of examples and the included drawings. In the drawings, same reference numerals refer to same or analogous elements. The figures show schematically:

(2) FIG. 1 a flow chart of a method for manufacturing devices by replication including conditioning of the replication tool;

(3) FIG. 2 a schematic illustration of a replication tool, in a cross-sectional view;

(4) FIG. 3 a schematic illustration of the replication tool of FIG. 2 during exposure to conditioning material, in a cross-sectional view;

(5) FIG. 4a a moving towards each other of the replication tool of FIGS. 2 and 3 and a substrate, with replication material therebetween in a cross-sectional view;

(6) FIG. 4b a schematic illustration of shaping of replication material during an embossing process using the replication tool of FIGS. 2 and 3, in a cross-sectional view;

(7) FIG. 5 a schematic illustration of a removal of the replication tool of FIGS. 2 to 4 from produced devices, in a cross-sectional view;

(8) FIG. 6 a strongly schematized illustration of times and dimensions during conditioning and manufacturing.

(9) The described embodiments are meant as examples or for clarifying the invention and shall not limit the invention.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 is a flow chart of a method for manufacturing devices by replication including conditioning of the replication tool. FIGS. 2 to 5 are schematical illustrations, in a cross-sectional view, of some steps of the method. The illustrated example refers to a replication process which is an embossing process.

(11) In the following, manufacturing methods and replication tool conditioning methods are described with reference to FIG. 1 as well as to FIGS. 2 to 5.

(12) In step 100, the replication tool is produced which can include shaping a tool material of the replication tool. This shaping can be accomplished, e.g., in a replication process.

(13) FIG. 2 schematically illustrates a replication tool 1 in a cross-sectional view which is a wafer-level replication tool for embossing. It includes a tool material 2 which adheres to a rigid carrier 3 such as a glass plate. The tool material establishes a number of replication sites 4, four of which are illustrated in FIG. 2. In each replication site, a replication surface 5 is provided which exhibits the negative of the shape of a surface of a device to be produced by replication using the replication tool 1.

(14) Replication tool 1 includes mutually distanced replication sites, for the manufacture of separate devices by replication, such as a multitude of microlenses.

(15) The tool material can be an resilient material, and it can be a material which is interspersed pores and/or channels.

(16) The tool material can be a spongy material.

(17) The tool material can be, e.g., a polydimethylsiloxane (PDMS).

(18) In step 110, the replication tool 1 is conditioned before it is used for producing the devices by replication using the replication tool 1. The conditioning includes exposing the tool material 2 to a conditioning material 6, cf. FIG. 3. For this, the conditioning material 6 is applied to the tool material 2.

(19) FIG. 3 is a schematic illustration of the replication tool 1 of FIG. 2 during exposure to the conditioning material 6, in a cross-sectional view. Each replication surface 4 is covered by the conditioning material 6. In the illustrated example, the tool material 2 is covered by the conditioning material 6 even in full (except, e.g., for side faces of the tool material). Alternatively, the conditioning material 6 could also be applied locally to the replication surfaces 5. This is not illustrated in FIG. 2, but may look similar to what is illustrated in FIG. 4a (cf. below)—of course, with conditioning material 6 instead of replication material 9; and a substrate such as substrate 11 in FIG. 4a may be applied as well.

(20) The conditioning material 6 can be the same as a replication material 9 used later on in the replication processes (cf. step 130 and FIGS. 4 to 5). E.g., they can both be the same epoxy resin.

(21) The exposure of the tool material 2 to the conditioning material 6 can last, e.g., 6 hours—which largely exceeds the time duration during which the tool material 2 will be exposed in subsequent replication processes (cf. step 130 and FIGS. 3 and 4). In reaction to the exposure to conditioning material 6, tool material 2 is slightly dimensionally changed, e.g., undergoes a slight swelling process.

(22) For example, a portion of conditioning material 6 can afterwards be present in pores and channels of an open porous structure of tool material 2, wherein it can have replaced a portion of material, e.g., of PDMS precursors and uncured PDMS, respectively, present in the pores and channels prior to the exposure to conditioning material 6.

(23) Subsequently, conditioning material 6 is removed from tool material 1, cf step 120. Thereupon, replication tool 1 can look nearly like illustrated in FIG. 2, wherein, however, very small dimensional changes would have taken place relative to the state before the conditioning—which make the difference.

(24) A possible way of removing conditioning material 6 from replication tool 1 is to harden the initially liquid conditioning material 6, e.g., by exposing it to energy, such as by irradiating it with UV radiation and/or by heating it, and then to remove the hardened conditioning material. As mentioned above, conditioning material 6 can itself be a replication material, such as an epoxy resin or another curable material. The removal can be facilitated by using the above-mentioned substrate, which can be removed from the replication tool with the (hardened) conditioning material adhering to the substrate.

(25) Before carrying out a replication process for manufacturing devices by replication using replication tool 1, cf. step 130, some time may pass. According to current understanding, the dimensional change of the tool material is partially undone during that time. The time can be, e.g., of the order of the duration of the exposure of the tool material to the (still liquid) conditioning material. During that time, the replication tool (with no conditioning material and no replication material attached) can simply be retained, e.g., shelved or otherwise stored. Protection from dust during that time can be valuable. And temperature and humidity control can be helpful for increased reproducibility.

(26) In the replication process which in the illustrated embodiment is an embossing process, a replication material 9 is applied between tool material 2 and a substrate 11 which can be a rigid plate such as a glass plate. Replication material 9 can be applied locally, in a plurality of separate portions. In FIG. 4a, this is the case, and replication material 9 is applied to tool material 2, but, e.g., application to substrate 11 (in addition or alternatively) would be possible, too.

(27) With replication material 9 between substrate 11 and replication tool 1 (more specifically: tool material 2), these two are moved towards each other, e.g., until they abut each other, cf. FIG. 4b. In this position, replication material 9 is shaped at the replication sites 4 of replication tool 1, and more particularly, each portion of the applied replication material 9 is shaped by one of the replication surfaces 5. At the same time, replication material 9 is in contact with substrate 11, too.

(28) While maintaining the relative position of substrate 11 and replication tool 1, replication material 9 is hardened, e.g., cured, e.g., by UV irradiation and/or by application of heat.

(29) The time duration during which the tool material 2 is exposed to replication material 9 in its initial state (i.e. before replication material 9 is hardened), can be, e.g. less than one hour, and in particular less than 10 minutes.

(30) After the hardening process, a plurality of separate devices 10 is produced on substrate 11 each of which has a surface having a shape corresponding to the negative of the shape of one of the replication surfaces 5, and replication tool 1 is removed, cf. FIG. 5.

(31) The dimensions of devices 10 can be very precisely predetermined by means of a suitable conditioning process as described, and they can decisively differ from the dimensions that would result without the conditioning process.

(32) In mass production of devices 10 such as of passive optical components, e.g., of optical lenses, one and the same replication tool 1 can be used in several replication processes which are successively carried out. E.g., step 130 and the sequence of process steps described in conjunction with FIGS. 4 to 5, respectively, is repeatedly carried out.

(33) Without subjecting the tool material 2 to the described conditioning process prior to the replication processes for the production of the devices 10, the devices 10 produced in the first couple of replication processes would have slightly but notably differing dimensions which would lead to a considerable number of rejects in high-precision manufacture. Only after several replication processes carried out with one and the same replication tool, sufficiently dimensionally stable results would possibly be achieved without the conditioning.

(34) The conditioning, however, effects that devices 10 with only very little dimensional variations are produced already in the first couple of successive replication processes, such that little rejects occur already from the beginning.

(35) FIG. 6 is a strongly schematized illustration of times and dimensions relevant during conditioning and manufacturing. It shall provide further insight into the manufacturing process and into the interrelation between conditioning and manufacturing. FIG. 6 is not to scale.

(36) The x-axis of FIG. 6 roughly corresponds to a time axis, illustrating the steps which are carried out one after the other in the indicated order. The y-axis is indicative of a dimension of the replication tool or, more particularly, of the replication sites. Both axes are not to scale. The y-axis can thus be indicative of, e.g., a linear dimension of a feature of a replication surface and thus, be indicative, e.g., of a parameter (“target parameter”) of a device produce, such of as a dimension (“target dimension”) of a feature of a device produced, such as of a diameter of a microlens. Value R assigned to the y axis can thus be, e.g., a relative value relating a target dimension of a feature of a replication surface or of a feature of a replicated device to a desired value (or set value) thereof. E.g., R can be R=x/x0, wherein x is the target parameter, e.g., a diameter or a focal length, of a replicated microlens, and x0 is the corresponding desired value (or set value).

(37) Indications “d” at the x-axis designate times when material (conditioning material and replication material, respectively) is applied to the replication tool, e.g., dispensed on the tool material using a dispenser. A substrate can afterwards be attached to the material, as discussed above. Indications “h” at the x-axis designate times when the material is hardened, e.g., cured, e.g, by UV irradiation. After hardening is completed, the hardened material is removed from the tool material, e.g., by removing the substrate (with the replicated devices attached) from the replication tool.

(38) The ellipses in FIG. 6 indicate measured values of R or, more precisely, their centers indicate average values of R, averaged over all the devices produced in the respective run. The lengthy elliptic shape symbolizes that values of the target parameter tend to vary among a plurality of devices produced in a single replication process (and likewise in the conditioning process).

(39) It is noted that frequently, a multitude of devices is produced on a single wafer. These devices do, in practice, of course have varying values of the target parameter. Therefore, the discussed values, in particular the values of R, can be understood as average values. And similarly, also the dimension of replication sites on the replication tool can be understood as average values.

(40) Average values can be determined, e.g., as arithmetic averages.

(41) A dashed line is drawn in FIG. 6 as a rough guide to the eye indicative of the time development of R. Of course, R is more likely to change rather in form of higher order polynomial functions or along exponential functions or the like. But for reasons of simplicity, straight lines are drawn in FIG. 6.

(42) The curve for relative value R can be determined, e.g., by determining or measuring the respective feature dimension(s) of the replication tool at the desired time. Alternatively or in addition, at least the portions in which the dashed curve for R is rising, i.e. in the phases after application of the material to the tool material, can be determined, at least approximately, by hardening the material at the desired time and determining/measuring the respective target parameter (e.g., target dimension) of the replicated device.

(43) Going from left to right on the x-axis and thus following the time development, and with reference, too, to FIG. 1:

(44) After manufacture of the replication tool (cf. also step 100), conditioning material is applied to the tool material at the first “d”, and R increases (step 110). Until hardening (at “h”), a relatively long time passes, and R assumes a maximum value, which not necessarily corresponds to a saturation value at which no further increase of R would occur even if the tool material would be still further exposed to the conditioning material. The maximum value can correspond to, e.g., 80% of such a saturation value.

(45) After hardening, the conditioning material is removed and discarded (cf step 120). The corresponding devices are (usually) not within an acceptance band for the respective target parameter. However, e.g., for test purposes and/or for monitoring reproducibility, their target parameter values can be determined.

(46) Such an acceptance band is indicated in FIG. 6 (thin dotted lines). E.g., devices may be acceptable if R is between 0.99 and 1.01; i.e. 1% deviation from the set value would be acceptable.

(47) The maximum value can deviate from 1 by, e.g., more than the full width of the acceptance band. In FIG. 6, the maximum value of R deviates from 1 by more than twice the full width of the acceptance band.

(48) Subsequently, it turns out that R decreases until it is exposed to the replication material (at the second “d”). During that time (retaining time), which can be even longer than the time of exposure to the conditioning material, the replication tool is reposited, e.g., is simply shelved.

(49) The conditioning phase (designated “C” in FIG. 6) can end here, and the manufacturing phase (designated “M” in FIG. 6) can begin (cf step 130).

(50) After the second “d”, R increases again, but not very much, as not much time passes up to the hardening of the replication material at the second “h”. R is within the acceptance band, and the replicated devices can therefore be used. It is, however, also possible to discard these firstly manufactured devices. E.g., they can be used to verify that they are indeed within the acceptance band. And/or they are discarded because they may contain contaminants possibly picked up during the retaining time or for other reasons.

(51) Up to the next “d”, R decreases again, but not very much, as not much time passes up to the next deposition of the replication material on the tool material at the third “d”. Afterwards, R increases again until the next hardening process. And so on.

(52) As is also readily understood, tests can be carried out for determining the times during the conditioning phase, namely for determining suitable values for the time of exposure to the conditioning material and for the time from hardening the conditioning material to the beginning of the following exposure to the replication material.

(53) And, as is also readily understood, tests can be carried out (cf. below for an example) for determining suitable values for the time of exposure to the replication material and for the time from hardening the replication material to the beginning of the next exposure to the replication material during the manufacture—which can both be much shorter than the corresponding times during the conditioning phase.

(54) The times to be used in the manufacturing phase M can be determined in dependence of the times used in the conditioning phase C or vice versa.

(55) This way, optimized times can be determined, such that acceptable devices, e.g., devices with R within the acceptance band, can be reproducibly produced—with no or only very little rejects.

(56) In an example, the times are considered suitable (acceptable/as desired) when they are selected such that for the devices produced in the replication processes (in the manufacturing phase), a mean deviation of target parameter values from a mean value of the target parameter values
is at most 50% (or more particularly at most 35%) of a deviation from said mean value of the target parameter values of the devices produced in the replication processes, of a mean value of target parameter values of devices produced in the conditioning phase (such as by hardening the conditioning material at the end of time duration t1).

(57) In a very simple numeric example for this, merely two devices, e.g., two lenses, per replication tool (and, accordingly, also per replication process) are assumed, and the target parameter is, e.g., the lens diameter, and only two replication processes are carried out during the manufacturing phase. During the conditioning phase, one lens has a target parameter value (lens diameter) of 108 μm, and the other lens has a target parameter value of 112 μm. In the first replication process, the lenses have target parameter values of 102 μm and 104 μm, respectively, and in the second replication process, of 96 μm and 98 μm, respectively. Taking the arithmetic mean for calculating the mean values, we have, for the devices produced in the replication processes, a mean value of (102 μm+104 μm+96 μm+98 μm)/4=100 μm. Taking the standard deviation as the mean deviation, we have the square root of ((102−100).sup.2+(104−100).sup.2+(96−100).sup.2+(98−100).sup.2)/4 in micrometers as the mean deviation for the devices manufactured during the manufacturing phase, which is the square root of 10 in micrometers and thus amounts to approximately 3.16 μm.

(58) The mean value of the target parameter values of the lenses produced in the conditioning phase is (108 μm+112 μm)/2=110 μm. The deviation of this value from the above-calculated mean value of 100 μm thus is 10 μm. This deviation of 10 μm is more than three times the above-calculated mean deviation of approximately 3.16 μm. Accordingly, the times used for producing devices of this example do result in acceptable lenses.

(59) If the condition for acceptability were that a mean deviation from a target value of target parameter values of the devices produced in the replication processes is smaller by a factor of at least two than a mean deviation from the target value of the target parameter values of devices produced by hardening the conditioning material at the end of time duration t1, the lenses of the above example would be acceptable if the target value is 100 μm. However, if the target value would be 110 μm, the lenses were not acceptable, and the times chosen would thus not be suitable.

(60) If the condition for acceptability were that an acceptance band around the target value is defined for the devices produced in the manufacturing phase, and that a mean value of the target parameter of the devices produced in each the at least two replication processes lies within the acceptance band, the selected times would fulfill the condition and the lenses would be acceptable, if the acceptance band extends from, e.g., 94 μm to 104 μm (and the target value is, e.g., 100 μm). If, however, the acceptance band extends from 98 μm to 104 μm (and the target value is, e.g., 101 μm), the times used during conditioning and manufacture would not be suitable, because the mean value of the target parameter values in the second replication process is (96 μm+98 μm)/2=97 μm, which is outside the acceptance band.

(61) Changes in R during the manufacturing phase M tend to be relatively small if the times used during the manufacturing phase M are relatively short. This can simplify to reproducibly produce acceptable devices.

(62) In an example for determining suitable times, e.g., relatively short times (exposure times, retaining times) to be used during the manufacture can initially be selected. Then, test runs can be accomplished, using different replication tools including identical tool material, e.g., using congeneric replication tools. In the test runs, different times of exposure to the conditioning material and/or different values for the subsequent retaining time are selected, whereafter optionally, the values of the target parameter of the so-produced devices of the conditioning material are determined, e.g., by measuring a width of these devices. If the values of the target parameter in respective subsequent replication processes are as desired, e.g., because they lie within an acceptance band, suitable times are found. To find suitable times, one can, e.g., firstly select a time of exposure to the conditioning material and vary, in some test runs, the subsequent retaining time. If the result is not as desired, a different time of exposure to the conditioning material is selected and, again, the subsequent retaining time is varied in successive test runs. If then still, the result is not as desired, the exposure times and/or the retaining times can be varied in further test runs according to the before-described scheme (varying the times used during the respective conditioning phase).

(63) Following the above scheme in a number of test runs, suitable times (during conditioning and during manufacturing) can be determined—such that devices are reproducibly produced in the manufacturing phase which, e.g., exhibit, at least to a high percentage, values of the target parameter which lie within an acceptance band, or devices which have values of the target parameter (in short: “target parameter values”) which exhibit a mean deviation from a mean value of the target parameter values which is at most half as large as a deviation from said mean value of the target parameter values (during the manufacturing phase), of a mean value of the target parameter values of devices produced during the conditioning phase (i.e. produced by hardening the conditioning material at the end of time duration t1).

(64) In the discussed examples, feature dimensions at the replication tool increase after application of the conditioning material and of the replication material, respectively. However, it may in instances be possible that they decrease.