阅读说明：本技术 制造多个光学元件的方法及其产品 (Method of manufacturing a plurality of optical elements and products thereof ) 是由 尼古拉.斯普林 余启川 于 2020-03-11 设计创作，主要内容包括：一种制造多个光学元件(140)的方法,该方法包括:提供第一晶圆(120),该第一晶圆(120)具有在第一晶圆(120)的第一侧上形成光学元件(140)的硬化复制材料；提供第二晶圆(121),该第二晶圆(121)具有在第二晶圆(121)的第一侧上形成光学元件(140)的硬化复制材料；在光学元件(140)之间在第一晶圆(120)的第一侧上沉积液滴(180),使第一晶圆(120)的第一侧与第二晶圆(121)的第一侧对准；以及将两个晶圆(120,121)放在一起,使得第一晶圆(120)的第一侧上的液滴(180)粘附到第二晶圆(121)的第一侧上。(A method of manufacturing a plurality of optical elements (140) comprises providing a first wafer (120), the first wafer (120) having a hardened replication material forming the optical elements (140) on a first side of the first wafer (120); providing a second wafer (121), the second wafer (121) having a hardened replication material forming optical elements (140) on a first side of the second wafer (121); depositing droplets (180) on a first side of the first wafer (120) between the optical elements (140), aligning the first side of the first wafer (120) with a first side of the second wafer (121); and bringing the two wafers (120, 121) together such that the droplets (180) on the first side of the first wafer (120) adhere to the first side of the second wafer (121).)

1. A method of manufacturing a plurality of optical elements, the method comprising:

providing a first wafer having a hardened replication material forming optical elements on a first side of the first wafer;

providing a second wafer having a hardened replication material forming optical elements on a first side of the second wafer;

depositing droplets on a first side of the first wafer between the optical elements;

aligning a first side of the first wafer with a first side of the second wafer; and

the two wafers are brought together so that the droplets on the first side of the first wafer adhere to the first side of the second wafer.

2. The method of claim 1, wherein the droplets are formed of a high viscosity material that can be hardened.

3. The method of claim 2, comprising hardening the droplets.

4. The method of claim 2, wherein hardening the droplets comprises curing the droplets with UV radiation.

5. The method of claim 1, further comprising depositing droplets on the first side of the second wafer between the optical elements.

6. The method of claim 5, wherein the droplets are formed of a high viscosity material that can be hardened.

7. The method of claim 6, comprising hardening the droplets.

8. The method of claim 7, wherein hardening the droplets comprises curing the droplets with UV radiation.

9. The method of any preceding claim, wherein depositing droplets comprises adjusting a volume of each droplet to produce a desired separation distance between the first wafer and the second wafer.

10. An apparatus, comprising:

a first wafer having a hardened replication material forming optical elements on a first side of the first wafer;

a second wafer having a hardened replication material forming optical elements on a first side of the second wafer; and

a spacer connecting the first wafer and the second wafer, wherein the spacer is shaped as a meniscus.

11. The device of claim 10, wherein the spacers are formed by a process comprising:

depositing droplets on a first side of the first wafer between the optical elements;

aligning a first side of the first wafer with a first side of the second wafer; and

the two wafers are brought together so that the droplets on the first side of the first wafer adhere to the first side of the second wafer.

12. The apparatus of claim 11, wherein the droplets are formed of a hardened high viscosity material that can be hardened.

13. The apparatus of claim 12, wherein the droplets are hardened by curing the droplets with UV radiation.

14. The apparatus of claim 11, further comprising depositing droplets on the first side of the second wafer between the optical elements.

15. The apparatus of claim 14, wherein the droplets are formed of a high viscosity material that can be hardened.

16. The apparatus of claim 15, wherein the droplets are hardened by curing the droplets with UV radiation.

17. The apparatus of any of claims 11 to 16, wherein depositing droplets comprises adjusting a volume of each droplet to produce a desired separation distance between the first wafer and the second wafer.

Technical Field

The present disclosure relates to liquid spacer alignment features.

Background

Optical devices comprising one or more optical radiation emitters and one or more light sensors may be used for a wide range of applications including, for example, distance measurement, proximity sensing, gesture sensing and imaging. Miniature optoelectronic modules, such as imaging devices and light projectors, employ optical assemblies that include lenses or other optical elements stacked along the optical axis of the device to achieve desired optical performance. The replication optical element comprises a transparent diffractive and/or refractive optical element for influencing the light beam. In some applications, such optoelectronic modules may be contained in housings for various consumer electronics products, such as mobile computing devices, smart phones, or other devices.

Disclosure of Invention

The present disclosure describes optical and optoelectronic assemblies including micro-spacers, and methods for fabricating such assemblies.

The substrate may be a "wafer" or other elemental device with additional structures added thereto, for example, having hardened replication material structures adhered thereto, defining the surface of a plurality of optical devices, having some lithographically added or removed features (such as holes, etc.) or having other structures. The substrate may comprise any material or combination of materials.

The optical elements may be any element that affects the light illuminating them, including but not limited to lenses/collimators, pattern generators, deflectors, mirrors, beam splitters, elements for decomposing radiation into its spectral components, and the like, and combinations thereof. The replicated structures on one side of the substrate and the set of two aligned replicated optical elements on both sides of the substrate are both referred to as "optical elements".

The tool (or "replication tool") may comprise a first hardened material forming a rigid backplane and a second softer material portion (replication portion) forming both the contact spacer portion and the replication section. In general, the contact spacer portion may be the same material as the portion of the tool that forms the replication section, and may simply be a structural feature of the tool (not an added element). Alternatively, the contact spacer portion may include additional material, such as a soft and/or adhesive coating on the outermost surface.

Instead of a low stiffness material like PDMS, the contact spacer may also comprise an adhesive, e.g. an adhesive layer. The use of a low stiffness material for the entire replication section of the tool is advantageous for its manufacture, since no separate step is required for adding the contact spacers or their coating. The entire replica portion can be manufactured in a single shape by replication (molding, embossing, or the like) from a master or a sub-master also including the contact spacer portion.

The contact spacer portion is operable to rest against the substrate during replication, with no material between the contact spacer portion and the substrate. The contact spacer portion may be continuous or may comprise a plurality of discrete portions around the perimeter or distributed over a larger portion of the perimeter and/or interior of the replication surface. In other words, the contact spacer portion may be of any configuration that allows the replication tool to rest on the substrate. For example, the contact spacer portions are distributed such that the contact spacer portions are located on both sides of a line in each plane that intersects the centroid of the tool. The spacers are arranged and configured such that if the tool is located on the substrate, the thickness (z-direction perpendicular to the substrate and tool plane) is defined in part by the spacers.

In some embodiments, a method of manufacturing a plurality of optical elements includes providing a first wafer having a hardened replication material forming optical elements on a first side of the first wafer, providing a second wafer having a hardened replication material forming optical elements on a first side of the second wafer, depositing droplets on the first side of the first wafer between the optical elements, aligning the first side of the first wafer with the first side of the second wafer, and bringing the two wafers together such that the droplets on the first side of the first wafer adhere to the first side of the second wafer.

In some cases, the droplets are formed of a high viscosity material that can be hardened. The method includes hardening the droplets. Hardening the droplets includes curing the droplets with UV radiation. The method includes depositing droplets on the first side of the second wafer between the optical elements. The droplets are formed of a high viscosity material that can be hardened. The method includes hardening the droplets, wherein hardening the droplets includes curing the droplets with UV radiation. Depositing the droplets includes adjusting a volume of each droplet to produce a desired separation distance between the first wafer and the second wafer.

In some embodiments, an apparatus includes a first wafer having a hardened replication material forming optical elements on a first side of the first wafer; a second wafer having a hardened replication material forming optical elements on a first side of the second wafer; and a spacer connecting the first wafer and the second wafer, wherein the spacer is shaped as a meniscus.

In some cases, the spacers are formed by a process comprising: depositing droplets on a first side of a first wafer between optical elements, aligning the first side of the first wafer with a first side of a second wafer, and bringing the two wafers together such that the droplets on the first side of the first wafer adhere to the first side of the second wafer. The droplets are formed of a hardened high viscosity material that can be hardened. The droplets are hardened by curing the droplets with UV radiation. The droplets may be deposited on the first side of the second wafer between the optical elements. The droplets are formed of a high viscosity material that can be hardened. The droplets are hardened by curing the droplets with UV radiation. Depositing the droplets includes adjusting a volume of each droplet to produce a desired separation distance between the first wafer and the second wafer.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 shows an exemplary cross-sectional tool/substrate structure for replication.

FIG. 2 shows replicated optical features with fields.

Figures 3A-3B illustrate liquid spacer alignment features.

Detailed Description

Fig. 1 schematically shows a cross-section through a tool 101 and a substrate 120. The tool 101 in the illustrated embodiment includes a rigid back plate 102 of a first material (e.g., glass) and a replica 104 of a second softer material (e.g., PDMS). The replication sections form a replication surface 108 comprising a plurality of replication sections 106, the surface of each replication section being a (negative) replica of the surface shape of the optical element to be manufactured. The replication sections 106 may be convex and thus define a concave optical element surface, or convex and define a concave optical element surface.

The replication section 104 has a contact spacer portion 112, which contact spacer portion 112 is illustrated as being arranged at the periphery. The contact spacer portion 112 is the structure of the replication tool 101 that protrudes the most in the z-direction. The contact spacer portion is substantially flat so that during replication, the contact spacer portion can operate to rest on the substrate 120 with no material between the contact spacer portion 112 and the substrate 120. The contact spacer portion 112 may, for example, form a ring around the perimeter of the replication surface 108, may include a plurality of discrete portions around the periphery, or may include a plurality of discrete portions distributed over a larger portion of the perimeter and/or interior of the replication surface 108.

The substrate 120 has a first side (e.g., substrate surface 126) and a second side, and may be any suitable material, such as glass. The substrate 120 also has a structure added to it, to which the replica will be aligned. The structure may for example comprise a coating 122 structured in the x-y plane, such as a screen with holes, or a structured infrared filter, etc. In addition, or in the alternative, the structure may include additional features, such as indicia and the like. In addition, or as another alternative, the structure may include a hardened replication material structure that forms a surface of the optical element.

To replicate the replication surface 108 of the tool 101, a replication material 124 is applied to the substrate 120 or the tool 101 or both the tool 101 and the substrate 120. Such application of the replication material 124 may include applying multiple portions of the replication material 124 (one portion per replication segment) to the tool 101 and/or the substrate 120 (although a single portion of the replication material 124 is shown in the figures). Each portion may be applied, for example, by jetting or splashing one or more droplets, by, for example, a dispensing tool that may operate in a manner similar to an inkjet printer. Each section may alternatively be made up of a plurality of sub-sections that are in contact with each other only during replication. Typically, the droplets are epoxy.

After applying the replication material 124, the substrate 120 and the tool 101 are aligned with respect to each other. For this purpose, a process similar to that used in so-called mask aligners may be used. The alignment process may include aligning at least one specific feature of the tool 101 and/or the substrate 120 (preferably two features are used) with at least one specific feature of the substrate 120 or the tool 101, respectively, or with a reference point of an alignment device. Features suitable for this include well-defined elements of the structure itself (such as defined corners or lens peaks of the structured coating, etc.), the addition of alignment marks in particular, or possibly also edges of basic elements, etc. As is known in the art, alignment also includes precisely making the tool and substrate surfaces parallel to avoid wedge errors; this parallelism may be performed prior to x-y alignment.

After alignment, the substrate 120 and tool 101 are brought together, the contact spacer portion 112 rests on the substrate surface and defines (with the floating spacers, if present) the z-dimension, and the tool is also locked against x-y movement. Thereafter, the substrate-tool-assembly is removed from the alignment station and transferred to a hardening station.

At least one surface of the replication section 104 of the tool or the contact spacer section 112 is made of a material having a relatively low stiffness, so that it is able to accommodate roughness of the micrometer and/or submicrometer scale under "normal" conditions, e.g. in the absence of a pressure greater than the pressure caused by gravity of the tool on the substrate, or vice versa, and can thus form a tight connection with the substrate surface. Furthermore, the replication portion of the tool or at least the surface contacting the spacer portion may have a relatively low surface energy, such that this adaptation to the roughness of the micrometer and/or submicrometer scale is advantageous. A preferred example of such a material is polydimethylsiloxane PDMS.

The previous replication step comprises hardening the replication material 124 after the replication tool 101 and the base element have been moved towards each other with the replication material 124 in between, and subsequently removing the replication tool 101.

Referring to fig. 2, during replication, when the tool and substrate 120 (e.g., glass) are in contact, excess replication material or epoxy applied during the jetting process typically spills over the region of interest and forms a field (yard) 130. As shown, the field 130 is generally circular. This circular field 130 is due to the addition of more epoxy 124 than is needed for each structure during replication, resulting in blooming. The additional epoxy 124 ensures that the full volume of replication material required for a particular structure is available (because the tolerance for the epoxy volume is not zero) and the additional liquid pool forms the field 130.

To control the flow of epoxy during replication, field line features (also referred to as "field lines," "line features," or "field line features") may be included in the design of the tool 101 to control the liquid flow of the replication material 124 when it is a liquid. Such features may be included in the mastering process itself (during laser writing) or may be added later in the stone-molding process, wherein the features may be configured as additional layers of epoxy. The field line features described herein may be integrated in various masters fabricated by different technologies (EBL, laser writer, etc.).

In some cases, a stack of optical elements is created using multiple substrates 120. For example, one or both of the optical element or substrate may be a dielectric filter or interference filter designed to operate in contact with a particular refractive index (e.g., air or vacuum), a polymer-based filter (e.g., infrared absorber), a diffuser (e.g., diffusing foil), or the like. The stack of optical elements comprises a first optical element and a second optical element separated from each other by a small air or vacuum gap. In assembly, the first and second element spacers are deposited on either side of the second optical element, respectively. Each element spacer may have the shape of, for example, a ring or a closed rectangular ring that laterally surrounds the air or vacuum gap. Thus, the first element spacer separates the first and second optical elements from each other and establishes a small fixed distance between them. The second element spacer protrudes from the opposite side of the second optical element and may be used to create another small air or vacuum gap between the second optical element and the device on which the subassembly is mounted.

X, Y and Z accuracy are important in forming replicated structures, including when a spacer is present between the two layers. For example, a high precision such as ± 5um may be required, which is expensive and difficult to implement.

Conventional spacers, such as the contact spacer portion 112 shown in fig. 1, require additional space for movement with features present on the substrate to provide alignment tolerances. Conventional spacers disadvantageously have a less accurate substrate-to-substrate distance due to additional bond line tolerances. This reduced accuracy has a negative impact on the performance and overall size of the replicated structures. Furthermore, conventional solid spacers can disturb the field structure.

Fig. 3A and 3B illustrate the use of liquid spacers 180, which liquid spacers 180 may be applied directly onto the substrate 120 in a liquid state. The liquid spacer 180 is made of a high viscosity material. Referring to fig. 3A, a network of high viscosity liquid spacer 180 material is dispensed on the substrate 120 at locations between hardened replication features 140 present on the substrate 120. The hardened replication features 140 may include an associated field 130. The liquid spacer 180 material may be dispensed continuously or discontinuously. For example, the liquid spacer 180 material may be dispensed as a grid of intersecting lines of straight or curved lines, or may be dispensed as a series of broken dots or lines.

The second substrate 121 (or fixture) with the hardened replication features 140 is then positioned relative to the first substrate 120. The liquid spacers 180 may also be continuously or discontinuously dispensed on the second substrate 121. The liquid spacers 180 may be dispensed on the second substrate 121 to be a mirror image of the liquid spacers 180 dispensed on the first substrate 120, for example, to be dispensed such that the liquid spacers 180 on the first substrate 120 and the liquid spacers 180 on the second substrate are in contact when they are in close proximity. Alternatively, the liquid spacers 180 on the second substrate 121 may be dispensed such that they contact regions of the first substrate 120 where no liquid spacers 180 are deposited.

The first substrate 120 and the second substrate 120 are close to each other. Once the first substrate 120 and the second substrate 121 are sufficiently close to each other, the liquid spacers 180 form a meniscus 182 as shown in fig. 3B. The meniscus 182 may be formed by a liquid material deposited on only the first substrate 120, only the second substrate 121, or a combination of both the first substrate 120 and the second substrate 121. Once the meniscus 182 is formed, the material is cured. The solidified and solidified meniscus 182 holds the layers of the first substrate 120 and the second substrate 121 in place relative to each other in the Z-direction.

The viscosity and surface tension of the liquid spacer 180 are known. The contact angle between the liquid spacer 180 and the substrate 120 (and/or 121) can be predicted, as can the ability of the liquid spacer 180 to maintain the circular shape of fig. 3A. The liquid spacers 180 should retain their circular shape for a time sufficient to allow the substrates 120, 121 to be brought together. At the same time, the viscosity and surface tension of the liquid spacer 180 material are selected such that capillary action allows the material to wet and adhere to both surfaces, forming a meniscus 182. By adjusting the volume and height (e.g. a height of 1-2 mm) of the dispensed deposited liquid spacer 180 material, the thickness of the resulting solidified liquid spacer element can be adjusted to a desired value.

The liquid spacer 180 traces may alternatively or additionally be applied to the surface of the second substrate 121 depending on the desired final distance between the substrates 120, 121. In this case, when the two substrates 120, 121 are aligned and brought together, the liquid spacer 180 material on each substrate merges and flows together to form the meniscus shape 182 shown in fig. 3B.

Such a liquid spacer process may also be used to add support structures to a conventional stack to improve stability during further processing (e.g., cutting).

The liquid spacers described herein advantageously reduce the need to maintain and store different spacer materials of different sizes, as any spacer width and height can be directly manufactured by controlling the dispensed volume of liquid spacer 180 material. The wafer-to-wafer distance (e.g., the distance d1 between the first and second substrates 120, 121) may also be modulated. This spacing method is a more cost effective way to keep the alignment in place during stack formation. The high viscosity of the liquid spacer 180 material allows for the incorporation of a portion of the hardened replication features 140 that were present prior to incorporation into the spacers, as well as adaptive tuning of spacer height in a highly controlled mask aligner/bonder.

The replication fabrication features described herein advantageously enable the creation of densely packed layouts and modules or stacks in which optical structures are combined with mechanical (e.g., spacers) or electrical functions (e.g., bond pads). These functions can be used to generate denser layouts, create packages that include eye-safe functions, reduce the number of process steps through ventilation channel generation, and improve accuracy.

Various embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.