Yard Control Features

Abstract

A method for manufacturing a plurality of optical elements, the method comprising: Providing a substrate (120); providing a tool (101) having a plurality of replication sections (106) on a replication side, each replication section (106) defining a surface structure of one of the optical elements, the tool (101) further comprising at least one contact spacer section (112), the contact spacer section (112) protruding further on the replication side as an outermost feature of the replication sections (106); wherein the substrate has halo features (138) around at least a portion of the plurality of corresponding replication sections (106), the halo features (138) being configured to hold replication material (124) on a first side of the halo features (138) and to act as a liquid barrier for the replication material (124) forming the optical elements, Aligning the tool (101) and the substrate (120) to each other and Bringing the tool (101) and the first side of the substrate (120) together, with replication material (124) between the tool (101) and the substrate (120), the contact spacer portion (112) contacting the first side of the substrate (120) and thereby causing the spacer portion (122) to adhere to the first side of the substrate (120) and form the replication material (124) into the optical elements; Curing the replication material (124); and Separating the tool (101) from the substrate (120), wherein the cured replication material (124) adheres to the substrate (120); characterized in that the method further comprises removing the halo features (138) from the substrate (120) after separating the tool (101) from the substrate (120).

Description

TECHNICAL FIELD

[0001] This disclosure relates to microfluidic alignment features. BACKGROUND

[0002] Optical devices containing one or more optical radiation emitters and one or more optical sensors can be used in a wide variety of applications, such as distance measurement, proximity sensing, gesture sensing, and imaging. Small optoelectronic modules such as imaging devices and light projectors use optical assemblies containing lenses or other optical elements stacked along the optical axis of the device to achieve the desired optical performance. Replicated optical elements include transparent diffractive and / or refractive optical elements for influencing an optical beam. In some applications, such optoelectronic modules can be incorporated into the housings of various consumer electronics devices, such as mobile computers, smartphones, or other devices.

[0003] US 2008 / 0 054 507 A1 relates to the field of manufacturing optical elements, in particular refractive optical elements and / or diffractive micro-optical elements, by means of a replication process comprising embossing or shaping steps. CN 1 02 004 274 A relates to a manufacturing method and the structure of a microlens, in particular to a manufacturing method and the structure of a microlens using a bank material layer to prevent adhesive residues. US 2017 / 0 087 784 A1 relates to the field of wafer-level manufacturing methods in general and in particular to the manufacture of devices in which one or more components are mounted on a substrate. US 2016 / 0 313 540 A1 relates to a lens manufacturing method based on a slotted substrate. SUMMARY

[0004] The present disclosure describes optical and optoelectronic assemblies incorporating micro-spacers and methods for fabricating such assemblies.

[0005] The substrate may be a "wafer" or other base element to which additional structure has been added, such as a hardened structure of replication material defining a surface of the multiple optical elements, with some lithographically added or removed features (such as apertures, etc.), or with some other structure. The substrate may be made of any material or combination of materials.

[0006] Optical elements can be any element that influences the light incident on them, including, but not limited to, lenses / collimators, pattern generators, deflectors, mirrors, beam splitters, elements for decomposing radiation into its spectral composition, etc., as well as combinations thereof. Both a replicated structure on one side of a substrate and an ensemble of two aligned replicated optical elements on two sides of a substrate are referred to as an "optical element."

[0007] The tool (or "replication tool") may consist of a first, hard material forming a rigid backplate and a second, softer material portion (replication portion) forming both the contact spacer portion(s) and the replication sections. Generally, the contact spacer(s) may be made of the same material as the portion of the tool forming the replication sections and may be merely structural features of the tool (not additional elements). Alternatively, the contact spacer portions may comprise an additional material, such as a coating of a soft and / or adhesive material on the outermost surface.

[0008] As an alternative to a low-stiffness material such as PDMS, the contact spacers can also contain an adhesive, e.g., an adhesive layer. Using a low-stiffness material for the entire replication portion of the tool is advantageous in terms of its manufacturing, as it eliminates the need for a separate step to add the contact spacers or coat them. The entire replica part can be manufactured in a single mold by molding (casting, stamping, etc.) from a master or sub-master that also contains the contact spacer part(s).

[0009] The contact spacers rest on the substrate during replication, with no material between the contact spacers and the substrate. The contact spacer sections can be continuous or comprise a plurality of individual sections distributed around the circumference or over a large portion of the circumference and / or the interior of the replication area. In other words, the contact spacer(s) can be in any configuration that allows the replication tool to rest on the substrate. For example, the distribution of the contact spacer section(s) is such that the contact spacer sections are located on either side of each in-plane line through the center of mass of the tool.The spacers are arranged and configured so that when the tool rests on the substrate, the thickness (the z-dimension perpendicular to the substrate and tool plane) is defined by the spacer sections.

[0010] According to the present invention, a method for manufacturing a plurality of optical elements comprises providing a substrate, providing a tool comprising a plurality of replication sections on a replication side, each replication section defining a surface structure of one of the optical elements, the tool further comprising at least one contact spacer section, the contact spacer section on the replication side protruding further than an outermost feature of the replication sections, the substrate comprising halo features around at least a portion of the plurality of corresponding replication sections, the halo features being configured to retain replication material on a first side of the halo features and to act as a liquid barrier for the replication material forming the optical elements;aligning the tool and the substrate with respect to each other and contacting the tool and the first side of the substrate, with replication material between the tool and the substrate, wherein the contact spacer portion contacts the first side of the substrate, thereby causing the spacer portion to adhere to the first side of the substrate and form the replication material into the optical elements; curing the replication material and separating the tool from the substrate, wherein the cured replication material adheres to the substrate. The method further comprises removing the halo features from the substrate after separating the tool from the substrate.

[0011] Embodiments may include one or more of the following features: The halo features surround the replication material applied to the substrate. Application of a first volume of replication material is performed, followed by application of a second volume of replication material, wherein the second volume is larger than the first volume. The first volume has a small volume tolerance. The halo features are formed in a resist layer on the substrate using a photolithographic process using a mask or by direct exposure. The replication material, which is located between the tool and the substrate, is applied by adhering a portion of the replication material to the tool and another portion of the replication material to the substrate, such that the replication material is divided in a ratio between the tool and the substrate.

[0012] A method for manufacturing a plurality of optical elements comprises providing a substrate having a resist layer on a first side of the substrate, providing a tool comprising a plurality of replication sections on a replication side, each replication section defining a surface structure of one of the optical elements, the tool further comprising at least one contact spacer section, the contact spacer section on the replication side protruding further than an outermost feature of the replication sections, aligning the tool and the substrate with respect to one another and bringing the tool and the first side of the substrate together, replication material being located between the tool and the substrate, the contact spacer section contacting the first side of the substrate and thereby causing the spacer section to adhere to the first side of the substrate,Curing the replication material into a feature and a space, separating the tool from the substrate with the cured spacer material adhering to the substrate and to the resist layer, and removing the resist layer from the substrate, thereby removing the cured material adhering to the resist layer.

[0013] Directing a laser beam around the perimeter of each replication section before separating the tool from the substrate. Directing the laser beam involves cutting through the yard material at the perimeter of each replication section, separating the feature and the hardened yard material. Removing the hardened yard material with a stripper. The hardened yard line material surrounds the replication material applied to the substrate. Applying a first volume of replication material, followed by a second volume of replication material, the second volume being larger than the first volume.

[0014] The details of one or more embodiments of the invention are illustrated in the accompanying drawings and the following description. Further features, objects, and advantages of the invention will become apparent from the description and drawings, as well as from the claims. Character list • Fig. Figure 1 shows an example of a cross-section of the tool / substrate structure for replication. • Fig. 2 shows a simulated optical feature with a halo. • Fig. 3A-3C show a method for applying farm control characteristics. • Fig. Figures 4A-4C show a method for applying farm control characteristics. • Fig. 5A-C show different embodiments of substrate halos. • Fig. 6A-6F shows a method for removing halo features. DETAILED DESCRIPTION

[0015] Fig. 1 schematically shows a cross-section through a tool 101 and a substrate 120. In the embodiment shown, the tool 101 comprises a rigid backplate 102 made of a first material, e.g., glass, and a replication section 104 made of a second, softer material, e.g., PDMS. The replication section forms a replication surface 108 with a plurality of replication sections 106, each of whose surfaces is a (negative) copy of a surface shape of an optical element to be produced. The replication sections 106 can be convex and thus form a concave surface of the optical element, or they can be convex and form a concave surface of the optical element.

[0016] The replication section 104 has contact spacer sections 112 arranged circumferentially in the illustration. The contact spacer sections 112 are the structures of the replication tool 101 that protrude the furthest in the z-direction. The contact spacer sections are substantially flat and can therefore rest against the substrate 120 during replication, with no material between the contact spacer sections 112 and the substrate 120. The contact spacer sections 112 can, for example, form a ring around the circumference of the replication surface 108, comprise a plurality of individual sections around the circumference, or comprise a plurality of individual sections distributed over a large part of the circumference and / or the interior of the replication surface 108.

[0017] The substrate 120 has a first side (e.g., the substrate surface 126) and a second side and may be made of any suitable material, e.g., glass. Also mounted on the substrate 120 is a structure to which the replica is to be aligned. The structure may, for example, comprise a coating 122 structured in the xy plane, such as a screen with openings or a structured IR filter, etc. The structure may additionally or alternatively include other features such as markings, etc. Additionally or alternatively, the structure may comprise a structure of hardened replication material forming a surface of the optical elements.

[0018] To replicate the replication surface 108 of the tool 101, replication material 124 is applied to the substrate 120 or the tool 101, or to both the tool 101 and the substrate 120. Such application of the replication material 124 may comprise applying a plurality of portions of the replication material 124 to the tool 101 and / or the substrate 120, one portion for each of the replication sections (although a single portion of the replication material 124 is shown in the figure). Each portion may be applied, for example, by jetting or ejecting a drop or a plurality of droplets through a dispensing tool, which may operate, for example, like an inkjet printer. Each portion may optionally consist of a plurality of sub-portions that only come into contact with each other during replication. Generally, the droplets are made of epoxy.

[0019] After the replication material 124 has been applied, the substrate 120 and the tool 101 are aligned with each other. For this purpose, a method similar to that used for so-called mask aligners can be used. The alignment process can comprise aligning at least one specific feature (preferably two features are used) of the tool 101 and / or the substrate 120 with at least one specific feature of the substrate 120 or the tool 101, respectively, or with a reference point of an alignment device. Suitable features for this purpose are well-defined elements of the structure itself (e.g., a defined corner of a structured coating or a lens tip, etc.), specifically applied alignment marks, possibly also edges, etc. of the base element, etc.As is well known in technology, alignment also includes the exact parallelization of the tool and substrate surfaces to avoid wedge errors; this parallelization can be performed before the xy alignment.

[0020] Following alignment, the substrate 120 and the tool 101 are brought together, with the contact spacers 112 resting against the substrate surface and (together with the floating spacers, if present) defining the z-dimension and also blocking the tool against xy movement. The substrate-tool assembly is then removed from the alignment station and transferred to a hardening station.

[0021] The replication section 104 of the tool or at least one surface of the contact spacer sections 112 is made of a material with a comparatively low stiffness, so that under "normal" conditions, where, for example, no greater pressure is exerted than that caused by the gravity of the tool resting on the substrate or vice versa, it can adapt to irregularities in the micrometer and / or submicrometer range and thus establish an intimate connection with the substrate surface. Furthermore, the replication section of the tool or at least the surface of the contact spacer section can have a comparatively low surface energy to promote such adaptation to irregularities in the micrometer and / or submicrometer range. A preferred example of such a material is polydimethylsiloxane PDMS.

[0022] The previous replication steps include curing the replication material 124 after moving the replication tool 101 and the base element with the replication material 124 therebetween towards each other, and then removing the replication tool 101. Control of the substrate level on the farm / flow control

[0023] As in Fig. 2, during replication, excess replication material or epoxy applied during jetting typically overflows the area of ​​interest, forming a halo 130 when the tool and substrate 120 (e.g., glass) are brought into contact. The halo 130 is typically circular, as shown. This circular halo 130 results from adding more epoxy 124 than is required for the particular structure during the replication process, resulting in overflow. The additional epoxy 124 ensures that the entire volume of replication material required for a particular structure is available (since the epoxy volume tolerance is non-zero), and the extra liquid collects to form the halo 130.

[0024] To control epoxy flow during replication, yardline features (also called "yard lines," "line features," or "yardline features") can be incorporated into the design of the tool 101 to control the flow of the replication material 124 while it is liquid. Such features can be added during the mastering process itself (during laser writing) or subsequently in a lithomold process, where the features can be patterned into an additional epoxy layer. The yardline features described here can be incorporated into all types of masters produced using different technologies (EBL, laser writer, etc.).

[0025] In some cases, there is insufficient space on the substrate 120 for an extended yard feature, or the volume and shape of the tool 101 used in the replication process lead to difficulties in controlling the flow of the replication material 124. In such cases, an additional flow control feature can be implemented on the substrate 120 as a temporary or permanent structure to guide and / or contain the liquid replication material 124 during the replication process. This arrangement also allows for controlled local delivery of replication material 124 onto the substrate 102 instead of the tool 101, or a combination of both (replication material 124 onto the substrate 102 and the tool 101).

[0026] Fig. 3A-4C illustrate the process of using halo control features 134 to create halo structures 130 that control the volume of excess replication material 124. Such halo control features 134 may include tool features 136 within the tool 101 itself and, in particular, substrate halo features 138 located on the substrate 120 itself. The substrate features 138 at the substrate level may reduce the overall footprint and shape of the resulting halo 130 and better define the volume of excess replication material 124.

[0027] The substrate halo features 138 are fabricated to surround the replication material 124 to be applied to the substrate 120. The first step of such a replication process typically involves using a small volume of the replication material 124 with a narrow volume tolerance. This small volume is followed by the use of a larger volume to define a larger structure bounded by the first small structure. The substrate halo features 138 can form ring-like features that act as a liquid barrier.

[0028] The fabrication of a first control structure in a multi-stage replication can be performed in a similar process to the replication itself, with the required structure being fabricated as a master structure (e.g., by laser writing or other technologies) from which a negative tool can be formed—for example, in a soft PDMS material on a glass backplane, as described above.

[0029] This tool can then be used to create a first structure by depositing material onto the tool, bringing it into contact with the substrate, and curing the replication material before separating the tool and substrate to guide the material of a subsequent step. This process can be repeated multiple times with different structures, depending on the complexity of the final structure.

[0030] The substrate bottom features 138 can be produced in different ways. In one method, a photolithographic process is used to produce the substrate bottom features 138 on the substrate 120 in a resist layer by means of a mask or by direct exposure. In this case, the substrate bottom features 138 can be removed after replication and curing of the material with a stripper (which leads to the configurations shown in the Fig. 3C and Fig. 4C). In the two-stage replication ( Fig. 3A-C), a simpler and smaller control feature is first created, and then the more complex and / or larger structure is replicated over it. This method offers the ability to divide the volume of replication material required to form the desired structure in any ratio between the tool 101 and the substrate 120. This allows for better control of the material flow and allows larger quantities to be distributed over smaller areas.

[0031] The Fig. 5A-C show various embodiments of the substrate halo features 138, which can be selected depending on the replication method used and the final requirements. Removal of the yard by lifting

[0032] As already mentioned in Fig. 2, excess replication material 124 or epoxy resin applied during injection flows over the area of ​​interest and forms a halo 130 when the tool and substrate 120 are brought into contact. The additional epoxy resin 124 ensures that the entire volume of replication material required for a particular structure is available (since the epoxy volume tolerance is non-zero), and the additional liquid collects to form the halo 130.

[0033] In some cases, there is insufficient space on the substrate 120 for an extended yard feature, or the volume and shape of the tool 101 used in the replication process lead to difficulties in controlling the flow of the replication material 124. The yards 130 require a lot of space and significantly increase the footprint of the modules. In such cases, it is advantageous to remove the yards 130 from the substrate 120.

[0034] As in the Fig. 6A-E, a resist layer 160 applied to the substrate 120 can be used to remove unwanted yard structures 130 caused by excess volume of the replication material 124. To perform the yard removal process, the resist layer 160 is first applied to the substrate 120. Then, the structure 162 is created in the resist layer 160. The cured replication feature 140 is created with the replication material 124. Once cured, the replication material 124 forms the desired cured replication feature 140, and the excess replication material 124 results in a halo 130 ( Fig. 6C).

[0035] To remove the unwanted halo feature 130, a laser 164 directs a laser beam 166 to intersect at the interface between the halo 130 and the hardened replica feature 140 ( Fig. 6D). The intersection area is generally designated 168 and, in the example shown, is a circle around the hemispherical hardened replication feature 140. To separate the hardened replication material 124 of the halo 130 from that of the hardened replication feature 140, the laser 164 may direct the laser beam 166 around the entire intersection area 158, e.g., in a circle corresponding to the circumference of the hardened replication feature 140.

[0036] As soon as the laser cut in the cutting area 168 is completed, the resist layer 162 is lifted off together with the halo 130 ( Fig. 6E). The result is the final hardened replication feature 140 without halo 130, as in Fig. 6F.

[0037] Previous methods for removing unwanted yards 130 also use a laser, specifically laser ablation. In this process, the cured epoxy of the yard is physically removed using a laser beam. Throughput is very low with this method because the entire yard area must be scanned and ablated with the laser, not just the perimeter of a replicated feature. In addition to scanning the area of ​​each yard, the laser ablation scan must remove every layer of each yard. In some cases, the entire yard area must be ablated multiple times to achieve a good result. The entire process can be lengthy. In addition, the ablation process is difficult to control because the height, thickness, and volume of the yard structure vary due to the overflow of replication material.

[0038] The Fig.The method for lifting the yard described in 6A - F significantly reduces the laser operation, since only a ring in the cutting area 168 of the hardened replication feature 140 and the yard 130 needs to be cut. Most of the yard material 130 is removed by peeling off the resist layer 160 below the yard from the surface of the substrate 120.

[0039] The features of replication manufacturing described herein advantageously enable the creation of densely packed layouts with modules or stacks in which optical structures and mechanical (e.g., spacers) or electrical functions (e.g., bond pads) are combined. The features can be used to create denser layouts, create housings with eye - safety features, reduce the number of process steps by venting the channel generation, and increase the precision.

[0040] While several embodiments of the invention have been described, it should be understood that various changes may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

[1] A method for manufacturing a plurality of optical elements, the method comprising: Providing a substrate (120); providing a tool (101) having a plurality of replication sections (106) on a replication side, each replication section (106) defining a surface structure of one of the optical elements, the tool (101) further comprising at least one contact spacer section (112), the contact spacer section (112) protruding further on the replication side as an outermost feature of the replication sections (106); wherein the substrate has halo features (138) around at least a portion of the plurality of corresponding replication sections (106), the halo features (138) being configured to hold replication material (124) on a first side of the halo features (138) and to act as a liquid barrier for the replication material (124) forming the optical elements, Aligning the tool (101) and the substrate (120) to each other and Bringing the tool (101) and the first side of the substrate (120) together, with replication material (124) between the tool (101) and the substrate (120), the contact spacer portion (112) contacting the first side of the substrate (120) and thereby causing the spacer portion (122) to adhere to the first side of the substrate (120) and to form the replication material (124) into the optical elements; Curing the replication material (124); and Separating the tool (101) from the substrate (120), wherein the cured replication material (124) adheres to the substrate (120); characterized by that the method further comprises removing the halo features (138) from the substrate (120) after separating the tool (101) from the substrate (120). [2] The method of claim 1, wherein the halo features (138) surround the replication material (124) applied to the substrate (120). [3] The method of claim 1, comprising applying a first volume of replication material (124) followed by a second volume of replication material (124), wherein the second volume is greater than the first volume. [4] A method according to claim 2 or 3, wherein the first volume has a low volume tolerance. [5] The method of any one of claims 1 to 4, wherein the halo features (138) are formed in a resist layer on the substrate (120) by a photolithographic process using a mask or by direct exposure. [6] The method of claim 5, further comprising removing the halo features (138) from the substrate (120) with a stripper. [7] The method of any one of claims 1 to 6, wherein the replication material (124) located between the tool (101) and the substrate (120) is applied by adhering a portion of the replication material (124) to the tool (101) and another portion of the replication material (124) to the substrate (120) such that the replication material (124) is distributed in a ratio between the tool (101) and the substrate (120).

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