A process for eliminating air bubbles and voids produced during embossing

Abstract

This invention discloses a process method for eliminating bubbles and voids generated during the imprinting process. By applying pre-UV curing and dispensing processes, the probability of voids and bubbles appearing in the lens is greatly reduced. Simultaneously, it increases the constraint of the lens boundary, ensuring that the lens does not overflow excessively during imprinting. In layout design, the allowance for excess adhesive can be appropriately reduced, improving substrate utilization and wafer yield.

Description

Technical Field

[0001] This invention relates to the field of optical wafer microlens imprinting process technology, and in particular to a process method for eliminating bubbles and voids generated during the imprinting process. Background Technology

[0002] During the local lens imprinting process, due to the proximity of the substrate and the mold, the imprinting adhesive is often forced to flow from the effective area to the ineffective area due to capillary action, resulting in voids with insufficient or no adhesive in the center of the lens. Figure 1 As shown. When the curvature or roughness of the bottom edge of the mold lens is too large, the flow rate of the imprinting adhesive 1 on the substrate 2 will be faster than the flow rate at the edge of the mold 3, such as... Figure 2 As shown. When the mold is in close contact with the wafer, the faster-flowing adhesive will seal off the slower-flowing adhesive, forming air bubbles, such as... Figure 3 As shown. Therefore, a simple and reliable method is needed to eliminate voids and bubbles generated during lens imprinting without damaging the optical properties. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention designs a process method to eliminate bubbles and voids generated during the imprinting process.

[0004] The present invention adopts the following technical solution:

[0005] A process for eliminating air bubbles and voids generated during the imprinting process, comprising the following steps:

[0006] S1. Wafer Surface Treatment: The wafer is placed in a plasma cleaning device for surface pretreatment to change the surface tension of the wafer and reduce the contact angle;

[0007] S2. Localized dispensing of adhesive in the mold: Calculate the dispensing quality of a single lens based on the designed lens volume and the density of the imprinted adhesive, and dispense adhesive in the effective area of ​​the mold.

[0008] S3. Pre-UV curing treatment: Place the mold with the adhesive applied into a UV curing chamber and subject it to short-term weak UV irradiation to activate the photosensitizer in the adhesive, induce the cross-linking reaction, and enhance the interaction force between colloidal molecules.

[0009] S4. Imprinting: According to the product design, the pre-UV cured mold, imprinting adhesive and the surface-pretreated wafer are placed into the imprinting equipment for imprinting.

[0010] S5. UV curing: Based on the curing characteristics of the imprinted adhesive, the adhesive is irradiated with ultraviolet light for a certain period of time to cure it into the designed structure.

[0011] S6. Demolding: Separate the cured imprinting adhesive from the mold. After the mold and wafer are separated, the imprinting adhesive forms the designed structure and is fixed on the wafer, completing the entire process.

[0012] Preferably, in step S1, the contact angle is reduced by 7° to 17°.

[0013] Preferably, in step S2, when dispensing the adhesive, ensure that the height of the adhesive is higher than the mold plane.

[0014] Preferably, in step S3, the short time is specifically 5-60 seconds, and the weak ultraviolet irradiation specifically has an ultraviolet irradiation intensity of 150 mw / cm². 2 ~300mw / cm 2 .

[0015] Preferably, the imprinting in step S4 should be performed within ten minutes after step S3.

[0016] Preferably, in step S4, the imprinting force of the imprinting device is ≤40N.

[0017] Preferably, in step S5, the ultraviolet light irradiation intensity is 150 mw / cm². 2 ~300mw / cm 2 The irradiation time is 300-1000 seconds.

[0018] The beneficial effects of this invention are as follows: This invention designs a process method to eliminate bubbles and voids generated during the imprinting process. By applying pre-UV curing and dispensing processes, the probability of voids and bubbles appearing in the lens is greatly reduced. Simultaneously, it increases the constraint of the lens boundary, ensuring that the lens does not overflow excessively during imprinting. In layout design, the reserved space for excess adhesive can be appropriately reduced, improving substrate utilization and wafer yield. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a structure in which existing imprinting adhesive forms a cavity in the middle of a lens;

[0020] Figure 2 This is a schematic diagram of a structure in which existing imprinting adhesive flows on the substrate and the edge of the mold;

[0021] Figure 3 This is a schematic diagram of a structure in which air bubbles are formed when existing imprinting adhesive is tightly bonded to a wafer;

[0022] Figure 4 This is a schematic diagram of the contact angle A of the wafer bonded with imprinting adhesive before plasma cleaning.

[0023] Figure 5This is a schematic diagram of the contact angle A of a wafer after plasma cleaning and bonding with imprinting adhesive.

[0024] Figure 6 This is a schematic diagram of a structure in which the embossing adhesive is applied inside the mold during the process of this invention.

[0025] Figure 7 yes Figure 6 A schematic diagram of a structure for pre-curing a mold after the middle-point adhesive is applied;

[0026] Figure 8 yes Figure 7 A schematic diagram of the adhesive state after pre-curing in UV light;

[0027] Figure 9 yes Figure 8 A schematic diagram of a structure in which a mold and adhesive are used to complete the imprinting process with a wafer;

[0028] Figure 10 yes Figure 9 A schematic diagram of a structure for UV curing of medium-pressure printed products;

[0029] Figure 11 yes Figure 10 A schematic diagram of the structure of a UV-cured product after demolding;

[0030] In the diagram: 1. Glue, 2. Substrate, 3. Mold, A. Contact angle. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0032] Example: A process for eliminating bubbles and voids generated during the imprinting process, the steps of which are as follows:

[0033] S1. Wafer Surface Treatment: The wafer is placed in a plasma cleaning system for surface pretreatment to change the surface tension and reduce the contact angle; for example... Figure 4 and Figure 5 As shown, the contact angle A between the wafer and the imprinting adhesive after plasma cleaning is reduced by 7°~17° compared to the contact angle A before plasma cleaning.

[0034] S2. Localized Mold Dispensing: Calculate the dispensing quality of a single lens based on the designed lens volume and the density of the imprinted adhesive, and dispense adhesive within the effective area of ​​the mold. During dispensing, ensure the adhesive level is higher than the mold plane. Figure 6 As shown;

[0035] S3, Pre-UV curing treatment: such as Figure 7As shown, the mold with the adhesive applied is placed in a UV curing chamber for a short period of weak UV irradiation. This activates the photosensitizer in the adhesive, inducing a low-level cross-linking reaction, enhancing the intermolecular interactions of the colloid, and reducing the influence of roughness and capillary action on the compressive movement of the colloid. The state of the adhesive after pre-UV curing is as follows. Figure 8 As shown; after this step is completed, the imprint must be applied within ten minutes;

[0036] S4. Imprinting: According to the product design, the pre-UV cured mold, imprinting adhesive, and surface-pretreated wafer are placed into the imprinting equipment for imprinting. The imprinting force of the equipment is ≤40N; Figure 9 As shown;

[0037] S5. UV Curing: Based on the curing characteristics of the imprinting adhesive, the adhesive is irradiated with ultraviolet light for a certain period of time to cure it into the designed structure, such as... Figure 10 As shown;

[0038] S6. Demolding: The cured imprinting adhesive is separated from the mold. After separation, the imprinting adhesive forms the designed structure and fixes it on the wafer, completing the entire process. Figure 11 As shown.

[0039] In step S3, the short duration is specifically 5-60 seconds, and the specific UV irradiation intensity is 150 mw / cm². 2 ~300mw / cm 2 .

[0040] In step S5, the ultraviolet light irradiation intensity is 150 mw / cm². 2 ~300mw / cm 2 The irradiation time is 300-1000 seconds.

[0041] This invention presents a process method to eliminate bubbles and voids generated during the imprinting process. By applying pre-UV curing and dispensing techniques, the probability of voids and bubbles appearing in the lens is significantly reduced. Simultaneously, it increases the constraint of the lens boundary, ensuring that the lens does not overflow excessively during imprinting. In layout design, the allowance for excess adhesive can be appropriately reduced, improving substrate utilization and wafer yield.

[0042] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A process for eliminating air bubbles and voids generated during the imprinting process, characterized in that, The steps of the process method are as follows: S1. Wafer Surface Treatment: The wafer is placed in a plasma cleaning device for surface pretreatment to change the surface tension of the wafer and reduce the contact angle; S2. Localized dispensing of adhesive in the mold: Calculate the dispensing quality of a single lens based on the designed lens volume and the density of the imprinted adhesive, and dispense adhesive in the effective area of ​​the mold. S3. Pre-UV curing treatment: Place the mold with the adhesive applied into a UV curing chamber and subject it to short-term weak UV irradiation to activate the photosensitizer in the adhesive, induce the cross-linking reaction, and enhance the interaction force between colloidal molecules. S4. Imprinting: According to the product design, the pre-UV cured mold, imprinting adhesive and the surface-pretreated wafer are placed into the imprinting equipment for imprinting. S5. UV curing: Based on the curing characteristics of the imprinted adhesive, the adhesive is irradiated with ultraviolet light for a certain period of time to cure it into the designed structure. S6. Demolding: Separate the cured imprinting adhesive from the mold. After the mold and wafer are separated, the imprinting adhesive forms the designed structure and is fixed on the wafer, completing the entire process.

2. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, In step S1, the contact angle is reduced by 7°~17°.

3. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, In step S2, when dispensing the adhesive, ensure that the height of the adhesive is higher than the mold plane.

4. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, In step S3, the short time is specifically 5-60 seconds, and the weak ultraviolet irradiation specifically has an ultraviolet irradiation intensity of 150 mw / cm². 2 ~300mw / cm 2 .

5. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, The imprinting in step S4 must be performed within ten minutes after step S3.

6. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, In step S4, the imprinting force of the imprinting device is ≤40N.

7. The process for eliminating bubbles and voids generated during the imprinting process according to claim 1, characterized in that, In step S5, the ultraviolet light irradiation intensity is 150 mw / cm². 2 ~300mw / cm 2 The irradiation time is 300-1000 seconds.

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