Technological method for eliminating bubbles and cavities generated in imprinting process

Abstract

The invention discloses a process method for eliminating bubbles and holes generated in an imprinting process, and the probability of the occurrence of the holes and the bubbles in a lens is greatly reduced through the application of pre-ultraviolet curing and a dispensing process. Meanwhile, the constraint of the lens boundary can be increased, and it is guaranteed that large-range overflow cannot occur in the lens imprinting process. And during typesetting design, the reserved space of excessive glue can be properly reduced, and the utilization rate of the substrate and the wafer output coefficient are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical wafer microlens imprinting process technology, and in particular to a process method for eliminating bubbles and cavities generated during the imprinting process. Background Art

[0002] During the local lens imprinting process, due to the proximity of the substrate and the mold, the imprinting glue is often forced to flow from the effective area to the ineffective area due to capillary action, resulting in the formation of a cavity with little or no glue in the middle of the lens, such as Figure 1 When the curvature of the bottom edge of the mold lens is too large or the roughness is too high, the flow speed of the imprint glue 1 on the substrate 2 will be faster than the flow speed on the edge of the mold 3, as shown in FIG. Figure 2 When the mold is close to the wafer, the glue with a faster flow rate will seal the glue with a slower flow rate, forming bubbles, such as Figure 3 Therefore, a simple and reliable method is needed to eliminate the voids and bubbles generated during the lens printing process without destroying the optical properties. Summary of the invention

[0003] In order to solve the above technical problems, the present invention designs a process method for eliminating bubbles and cavities generated during the imprinting process.

[0004] The present invention adopts the following technical solution: A process for eliminating bubbles and voids generated during an imprinting process, the process comprising the following steps: S1. Wafer surface treatment: Place the wafer in a plasma cleaning device for surface pretreatment to change the surface tension of the wafer and reduce the contact angle; S2. Local dispensing of mold: Calculate the dispensing quality of a single lens according to the designed lens volume and the density of the imprinted glue, and perform dispensing in the effective area of ​​the mold; S3, pre-UV curing treatment: put the mold after dispensing into the UV curing box, and irradiate it with weak UV for a short time to activate the photosensitizer in the glue, induce the cross-linking reaction, and enhance the interaction between the colloid molecules; S4, Imprinting: According to the product design, the mold after pre-UV curing, the imprinting glue and the wafer after surface pretreatment are placed in the imprinting equipment for imprinting; S5, UV curing: According to the curing characteristics of the imprint glue, use ultraviolet light to irradiate the colloid for a certain period of time to solidify it into the designed structure; S6. Demolding: Separate the cured imprint glue from the mold. After the mold and the wafer are separated, the imprint glue forms a design structure and is fixed on the wafer, completing the entire process.

[0005] Preferably, in step S1, the contact angle is reduced by 7° to 17°.

[0006] Preferably, in step S2, when dispensing glue, ensure that the height of the glue is higher than the mold plane.

[0007] Preferably, in step S3, the short time is 5 to 60 seconds, and the specific ultraviolet irradiation intensity of weak ultraviolet irradiation is 150 mw / cm 2 ~300mw / cm 2 .

[0008] Preferably, the stamping in step S4 needs to be performed within ten minutes after step S3.

[0009] Preferably, in the step S4, the imprinting force of the imprinting equipment is ≤40N.

[0010] Preferably, in step S5, the ultraviolet light intensity is 150 mw / cm 2 ~300mw / cm 2 The irradiation time is 300~1000 seconds.

[0011] The beneficial effects of the present invention are as follows: the present invention designs a process method for eliminating bubbles and voids generated during the imprinting process, and by applying the pre-UV curing and dispensing process, the probability of voids and bubbles in the lens is greatly reduced. At the same time, the constraints on the lens boundary can be increased to ensure that there will be no large-scale overflow during the lens imprinting process. In the layout design, the reserved space for overflow glue can be appropriately reduced to improve the substrate utilization rate and the wafer output coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of a structure in which a cavity is formed in the middle of a lens by existing embossing glue; Figure 2 It is a schematic diagram of a structure in which existing imprint glue flows on a substrate and on the edge of a mold; Figure 3 It is a structural schematic diagram of bubbles formed when the existing imprint glue is in close contact with the wafer; Figure 4 It is a structural schematic diagram of the contact angle A of the wafer combined with the imprint glue before plasma cleaning treatment; Figure 5 It is a structural schematic diagram of the contact angle A of the wafer combined with the imprint glue after plasma cleaning; Figure 6 It is a structural schematic diagram of dispensing embossing glue in a mold in the process of the present invention; Figure 7 yes Figure 6 A structural schematic diagram of a mold that has been glued in the middle and is pre-cured; Figure 8 yes Figure 7 A structural schematic diagram of the glue state after pre-curing treatment; Fig. 9 yes Figure 8 A schematic diagram of a structure in which the mold and glue are pressed with the wafer; Fig.10 yes Fig. 9 A schematic diagram of a structure in which a product is UV-cured after mid-pressing; Fig.11 yes Fig.10 A schematic diagram of a structure after the UV-cured product is demoulded; In the figure: 1. glue, 2. substrate, 3. mold, A. contact angle. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Embodiment: A process for eliminating bubbles and voids generated during the embossing process, the process comprising the following steps: S1. Wafer surface treatment: Place the wafer in a plasma cleaning device for surface pretreatment to change the surface tension of the wafer and reduce the contact angle; Figure 4 and Figure 5 As shown, the contact angle A of the wafer combined with the imprint glue after the wafer plasma cleaning treatment is reduced by 7°~17° compared with the contact angle A of the wafer combined with the imprint glue before the wafer plasma cleaning treatment.

[0014] S2. Local glue dispensing of mold: Calculate the glue dispensing quality of a single lens according to the designed lens volume and the density of the imprinted glue, and perform glue dispensing in the effective area of ​​the mold. When dispensing, ensure that the height of the glue is higher than the mold plane, such as Figure 6 As shown; S3, pre-UV curing treatment: Figure 7 As shown, the mold after dispensing is placed in a UV curing box and irradiated with weak UV light for a short time to activate the photosensitizer in the glue, induce a low degree of cross-linking reaction, enhance the interaction between colloid molecules, and reduce the influence of roughness and capillary action on the compressed movement of the colloid. The state of the glue after pre-curing treatment is as follows: Figure 8 As shown; after this step is completed, stamping must be carried out within ten minutes; S4, Imprinting: According to the product design, put the mold after UV curing, imprinting glue and the wafer after surface pretreatment into the imprinting equipment for imprinting. The imprinting force of the imprinting equipment is ≤40N; Fig. 9 As shown; S5, UV curing: According to the curing characteristics of the imprint glue, use ultraviolet light to irradiate the colloid for a certain period of time to solidify it into the designed structure, such as Fig.10 As shown; S6, demoulding: the cured imprint glue is separated from the mold. After the mold and the wafer are separated, the imprint glue forms a design structure and is fixed on the wafer, completing the entire process method, such as Fig.11 shown.

[0015] In step S3, the short time is specifically 5 to 60 seconds, and the specific ultraviolet irradiation intensity of weak ultraviolet irradiation is 150mw / cm 2 ~300mw / cm 2 .

[0016] In step S5, the UV light intensity is 150 mw / cm 2 ~300mw / cm 2 The irradiation time is 300~1000 seconds.

[0017] The present invention designs a process method for eliminating bubbles and voids generated during the imprinting process. By applying the pre-ultraviolet curing and dispensing process, the probability of voids and bubbles in the lens is greatly reduced. At the same time, the constraints on the lens boundary can be increased to ensure that there will be no large-scale overflow during the lens imprinting process. During the layout design, the reserved space for overflow glue can be appropriately reduced to improve the substrate utilization rate and the wafer output coefficient.

[0018] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A process for eliminating bubbles and voids generated during the imprinting process. Its characteristics are: The steps of the process are: S1. Wafer surface treatment: Place the wafer in a plasma cleaning device for surface pretreatment to change the surface tension of the wafer and reduce the contact angle; S2. Local dispensing of mold: Calculate the dispensing quality of a single lens according to the designed lens volume and the density of the imprinted glue, and perform dispensing in the effective area of ​​the mold; S3, pre-UV curing treatment: put the mold after dispensing into the UV curing box, and irradiate it with weak UV for a short time to activate the photosensitizer in the glue, induce the cross-linking reaction, and enhance the interaction between the colloid molecules; S4, embossing: according to the product design, the mold after UV curing, the embossing glue and the wafer after surface pretreatment are placed in the embossing equipment for embossing; S5, UV curing: According to the curing characteristics of the imprint glue, use ultraviolet light to irradiate the colloid for a certain period of time to solidify it into the designed structure; S6. Demolding: Separate the cured imprint glue from the mold. After the mold and the wafer are separated, the imprint glue forms a design structure and is fixed on the wafer, completing the entire process.

2. A process for eliminating bubbles and voids generated during the imprinting process according to claim 1, Its characteristics are: In the step S1, the contact angle is reduced by 7° to 17°.

3. A process for eliminating bubbles and voids generated during the imprinting process according to claim 1, Its characteristics are: In the step S2, when dispensing glue, ensure that the height of the glue is higher than the mold plane.

4. A process for eliminating bubbles and voids generated during an imprinting process according to claim 1, Its characteristics are: In step S3, the short time is specifically 5 to 60 seconds, and the specific ultraviolet irradiation intensity of weak ultraviolet irradiation is 150 mw / cm 2 ~300mw / cm 2 .

5. A process for eliminating bubbles and voids generated during an imprinting process according to claim 1, Its characteristics are: The stamping in step S4 needs to be performed within ten minutes after step S3.

6. A process for eliminating bubbles and voids generated during an imprinting process according to claim 1, Its characteristics are: In the step S4, the imprinting force of the imprinting equipment is ≤40N.

7. A process for eliminating bubbles and voids generated during an imprinting process according to claim 1, Its characteristics are: In step S5, the ultraviolet light intensity is 150 mw / cm 2 ~300mw / cm 2 The irradiation time is 300~1000 seconds.

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