Fabrication Method of Double-Sided Microlens Structure

Abstract

The present invention discloses a manufacturing method of a double-sided microlens structure. The manufacturing method includes: providing a substrate; coating a photoresist on the first surface and forming a first colloid through a photolithography process and a reflow process; performing pattern transfer etching to form a first microlens; bonding the first surface to a carrier wafer by using a bonding material; forming a second microlens on the second surface, and applying forced cooling to the carrier wafer during the etching process; releasing the bonding between the first surface and the carrier wafer to obtain a double-sided microlens structure. In the present invention, the first microlens on the first surface is tightly bonded to the carrier plate through a bonding material, and the purge cooling of the first surface is changed to the purge cooling of the carrier plate, which can avoid the influence of the first microlens on the purge of the cooling gas, improve the purge efficiency and uniformity of the cooling gas, and further avoid the problem of carbonization of part of the photoresist colloid caused by local temperature runaway, thereby avoiding the influence on the structure and appearance of the microlens on the second surface, and significantly reducing the defective rate during mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor microlens manufacturing, and particularly to a manufacturing method for a double-sided microlens structure. Background Art

[0002] The microlens structure plays a role in optical path shaping and is an important part of the optical device structure. With the requirements for improving computing power and miniaturizing the device structure, higher requirements are put forward for the number of lenses and the coupling efficiency.

[0003] Under this background, R & D personnel have developed double-sided structure lenses, which not only save the device size area but also have a higher coupling effect.

[0004] During the R & D process, the inventors of the present invention found that in semiconductor process manufacturing, the double-sided structure limits the implementation of the etching process, especially the impact of the double-sided convex lens structure is the greatest. This is because the back side of the etching process needs to be attached to the stage, and the wafer is cooled and dissipated heat through the circulating coolant below and the cooling gas (generally helium gas). Among them, the cooling gas blows the wafer and plays a major role in heat dissipation. The presence of the convex lens structure causes the cooling gas to not blow the wafer evenly, resulting in too high a wafer temperature. The high temperature brings about carbonization of the surface pattern photoresist, thus affecting the structure and appearance of the product, and further leading to the generation of defective products. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a manufacturing method for a double-sided microlens structure.

[0006] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include:

[0007] The present invention provides a manufacturing method for a double-sided microlens structure, which includes:

[0008] Providing a substrate, the substrate having a first surface and a second surface disposed opposite to each other;

[0009] Coating a photoresist on the first surface and forming a first colloid through a photolithography process and a reflow process;

[0010] Using the first colloid to perform pattern transfer etching on the first surface to form a first microlens on the first surface;

[0011] Bonding the first surface having the first microlens to a carrier wafer using a bonding material;

[0012] Coating a photoresist on the second surface and forming a second colloid through a photolithography process and a reflow process;

[0013] Perform pattern transfer etching on the second surface using the second colloid to form second microlenses on the second surface, and apply forced cooling to the carrier wafer during the etching process;

[0014] Release the bonding between the first surface and the carrier wafer to obtain a double-sided microlens structure.

[0015] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention at least include:

[0016] The manufacturing method provided by the present invention utilizes the idea of temporary bonding. The first microlenses on the first surface are tightly bonded to the carrier plate through a bonding material, and the purge cooling of the first surface is changed to the purge cooling of the carrier plate. This can avoid the influence of the first microlenses, especially the convex first microlenses, on the purge of the cooling gas, improve the purge efficiency and uniformity of the cooling gas, and further avoid the problem of carbonization of some photoresist colloids caused by local temperature out of control. Thus, it avoids the influence on the structure and appearance of the microlenses on the second surface, and significantly reduces the defective rate during mass production.

[0017] The above description is only an overview of the technical solution of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines with detailed drawings to illustrate as follows. Brief Description of the Drawings

[0018] Figure 1 is a schematic diagram of the bonding state of the manufacturing method provided by a typical embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of the complete process of the manufacturing method provided by a typical embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of the structure of the reflux device used in the manufacturing method provided by a typical embodiment of the present invention;

[0021] Figure 4 is a micrograph of the microlenses obtained by the manufacturing method provided by a comparative example of the present invention;

[0022] Figure 5 is a micrograph of the microlenses obtained by the manufacturing method provided by another comparative example of the present invention;

[0023] Figure 6 is a micrograph of the microlenses obtained by the manufacturing method provided by a typical embodiment of the present invention;

[0024] Figure 7 is a surface profile diagram of the microlenses obtained by the manufacturing method provided by another typical embodiment of the present invention;

[0025] Figure 8 This is the surface profile diagram of the microlens fabricated by the manufacturing method provided in a typical embodiment of the present invention.

[0026] Explanation of reference numerals: 1, water bath; 2, circulating liquid; 3, support structure; 4, lens structure; 5, cover plate. Detailed implementation manners

[0027] Some prior arts mention methods for fabricating double-sided microlenses. For example, in the Chinese invention patent with the publication number CN112630873A, it is proposed to coat photoresist on both sides of a glass substrate; place the glass substrate coated with photoresist on a lithography platform; use a lithography machine for exposure; perform a developing operation after exposure; put the developed glass substrate into a constant temperature oven; S6, transfer the photoresist pattern to the glass substrate through a pattern transfer method. However, the etching process currently cannot achieve synchronous etching on both sides, and only the method of etching front and back on both sides can be adopted. As shown in the background art of the present invention, this method will cause heat dissipation problems, resulting in various drawbacks.

[0028] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain and illustrate this technical solution, its implementation process, principles, etc.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0030] Moreover, relational terms such as "first" and "second" are only used to distinguish one component or method step with the same name from another, and do not necessarily require or imply any actual relationship or order between these components or method steps.

[0031] Refer to Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a method for fabricating a double-sided microlens structure, which includes the following steps:

[0032] Provide a substrate, the substrate having a first surface and a second surface disposed opposite to each other;

[0033] Coat photoresist on the first surface and form a first colloid through a lithography process and a reflow process;

[0034] Use the first colloid to perform pattern transfer etching on the first surface to form a first microlens on the first surface;

[0035] Bond the first surface having the first microlens to a carrier wafer using a bonding material;

[0036] The second surface is coated with photoresist and subjected to photolithography and reflow processes to form a second colloid;

[0037] Performing pattern transfer etching on the second surface by using the second colloid to form a second microlens on the second surface, and applying forced cooling to the carrier during the etching process;

[0038] The bonding between the first surface and the carrier is released to obtain a double-sided microlens structure.

[0039] Based on the above technical solution, the present invention combines the substrate and the carrier together through a bonding method, thereby providing good heat dissipation for the substrate, avoiding product defects caused by carbonization of the photoresist, and providing good protection for the first microlens on the first surface during the CMP / photolithography process.

[0040] The lens structure involved in the present invention is, for example, a double-sided convex lens / double-sided concave lens / one-side convex and one-side concave lens. The specific shape of the lens includes spherical / aspherical / cylindrical lens, and the substrate materials involved include Si / SiO2 / Ge / InP GaAs, etc., but are not limited to these.

[0041] The method of temporary bonding of the wafer adopted in the above technical solution not only plays the fixing and protection role played by traditional temporary bonding in the semiconductor field, but more importantly solves the heat dissipation problem. This problem has not been taken seriously in many precedents for the preparation of double-sided lenses, but is a special phenomenon noticed by the inventor of the present invention during the long-term production and research and development process, especially for some lens types with higher lens height and lower contact angle, this phenomenon becomes more and more obvious.

[0042] In the present invention, the bonding material between the carrier and the substrate not only plays the role of fixing and supporting / protecting the first surface, but also serves as a bridge for heat dissipation, which plays an important role in improving the product process. Regarding the most critical bonding process in the present invention, the present invention has also made certain improvements in heat dissipation performance. For example, in some embodiments, the bonding process specifically includes the steps of primary bonding, annealing treatment, and secondary bonding; the primary bonding is used to achieve the first combination of the first surface and the carrier, and the bonding pressure is removed during the annealing treatment and the temperature is used for treatment, and the bonding pressure continues to be applied during the secondary bonding.

[0043] In some embodiments, the temperature of the primary bonding and / or secondary bonding is 200-220° C., the time is 5-10 min, and the pressure is 2-6 kN; the temperature of the annealing treatment is 200-230 degrees, and the time is 10-20 min.

[0044] As a specific example, the anneal treatment can be carried out on the product after sequential bonding. The annealing temperature is 200 - 230 degrees, and the time is 10 - 20 minutes. After annealing, secondary bonding is carried out. The bonding conditions can also be slightly different from those of the primary bonding. This method can ensure that the structure of the intermediate bonding material is flat and smooth without voids, and improve its heat dissipation and flow guiding effect.

[0045] In some embodiments, the bonding process may further include the following steps:

[0046] Coat the bonding material on the first surface having the first microlens to form a bonding adhesive layer. After spin coating and baking, a bonding material layer is formed. Then, the bonding material layer is attached to the surface of the carrier wafer for pressure bonding.

[0047] In some embodiments, the thickness of the bonding adhesive layer is 1.1 - 1.3 times the height or depth of the first microlens.

[0048] As a typical example of the above embodiment, the spin coating thickness of the bonding layer material is set according to the height of the first surface lens, generally 1.1 - 1.3 times of it. Then bake for 10 - 20 minutes at a temperature between 120 - 150 °C. Finally, bond the substrate and the carrier wafer through a bonding device at 200 - 220 °C, with a bonding pressure of 2 - 6 kN and a bonding time of 5 - 10 minutes to ensure good bonding strength. For the selection of the bonding material, the debonding temperature should be above 250 degrees to prevent the bonding material from melting due to the concentration of the carrier wafer temperature during the etching process.

[0049] Regarding the specific processing processes of the first lens and the second lens, many existing processing methods can be referred to. Generally, lithography / etching processes are used to fabricate the lenses on the first / second surfaces; lithography includes steps such as spin coating / exposure / development / reflow, etc. The etching process can use inductively coupled plasma (ICP) dry etching. Appropriate etching gas components and ratios are selected according to different etching materials. For example, when quartz, silicon, or Ge is used as the substrate, fluorine-based gases such as SF6 / CF4 / CHF3 / C3F8 can be used. When InP or GaAs is used as the substrate, chlorine-based gases such as Cl2 / BCl3 can be used. At the same time, some O2 / H2, etc. are added to control the etching rate, and it is accurately transferred to the etched substrate according to the spherical shape of the resist.

[0050] Of course, the specific lithography and etching processes are not necessarily limited to the scope specifically exemplified in the present invention.

[0051] In addition, the present invention also makes certain improvements to the reflow process. The traditional thermal reflow method is to heat the structure using a hot plate to make the photoresist flow and form a shape. In some embodiments, the reflow process is carried out in a vapor condensation cycle manner. The vapor condensation cycle manner may specifically include the following process:

[0052] The heated circulating liquid forms vapor, and the lens structure to be processed by the reflux process is brought into contact with the vapor, so that the photoresist remaining after the lithography process forms the first colloid or the second colloid under the action of its own surface tension.

[0053] In some embodiments, the circulating liquid includes ethanol diluted with water and / or isopropanol; the heating temperature for the vapor condensation cycle is 80 - 100 °C, and the time is 2 - 5 min.

[0054] See Figure 3 As shown, the preferred reflux method adopted in the embodiments of the present invention avoids the problem of uneven surface type in hot plate reflux, and can solve some special surface type reflux methods, such as large - diameter low - contact - angle lenses. (For example, lenses with a diameter > 1 mm and a contact angle < 10°)

[0055] The reflux system mainly consists of a water - bath 1, a circulating liquid 2, a support structure 3, a lens structure 4, and a cover plate 5. This reflux system has a simple structure and is convenient to operate. The design of the cover - plate structure enables the solution to be condensed and reused;

[0056] The circulating liquid 2 can adopt solutions such as diluted alcohol / isopropanol, etc. The temperature of the water - bath 1 is set at 80 - 100 °C, and the reflux time is set at 2 - 5 min. After being heated, the lens structure 4 forms the morphology of colloidal micro - lenses under the combined action of tension and molecular force after the solution vaporizes. This method has a low set temperature, high reflux efficiency, uniform morphology, regular lens morphology, and SPD < 15 nm (SPD represents the profile deviation).

[0057] In some embodiments, the debonding temperature of the bonding material is above 250 °C.

[0058] In some embodiments, the carrier wafer is selected from silicon wafers, and the thickness of the carrier wafer is greater than the designed thickness of the double - sided micro - lens structure by 5 - 10 μm. In some specific examples, double - polished silicon wafers can be selected, with a thickness 5 - 10 μm larger than the theoretical product thickness, to compensate for the loss of sag caused by over - etching during the etching process; in addition, generally, the production of front - and - back - side mark marks can be completed through conventional double - sided lithography and etching processes, and the double - sided mark points are used for subsequent single - side lens lithography alignment. In the field of semiconductor technology, conventional bonding carrier wafers generally select lens quartz materials, while in the preferred case of the present invention, a carrier wafer of a silicon wafer is used as the bonding carrier wafer. This can not only ensure the same coefficient of thermal expansion as the wafer, but also the thermal conductivity of glass quartz is very high and its heat dissipation ability is poor, which cannot meet the requirements of this process product, and can ensure that TTV < 10 μm after bonding (TTV represents the total thickness variation, which is a commonly used parameter in wafer thickness measurement and describes the maximum positive deviation and maximum negative deviation of each point on the wafer relative to the average thickness).

[0059] In some embodiments, the forced cooling includes coolant circulation for temperature reduction and synchronous purging with cooling gas.

[0060] In the final debonding process, the substrate and the carrier can be separated by thermal slip by heating the wafer above 250°C, and the residual bonding material can be cleaned by soaking in a cleaning solution such as NMP.

[0061] The technical solutions of the present invention will be further described in detail below through several embodiments in conjunction with the accompanying drawings. However, the selected embodiments are only used to illustrate the present invention and do not limit the scope of the present invention.

[0062] Embodiment 1

[0063] This embodiment exemplifies the manufacturing process of a double-sided lens, which is specifically as follows:

[0064] 1. Use a double-polished silicon wafer with a thickness 5 μm larger than the theoretical product thickness. The theoretical product thickness is 500 μm, and a silicon wafer with a thickness of 505 μm is selected to compensate for the loss of sag caused by over-etching during the etching process.

[0065] 2. Complete the production of front and back mark markings through conventional double-sided lithography and etching processes; the double-sided marking points are used for subsequent single-sided lens lithography alignment.

[0066] 3. Make glue columns on the silicon lens through a conventional lithography process, and then place the wafer in Figure 3 the provided new reflux system for vapor condensation and circulation reflux. The reflux temperature is 80°C, and the reflux time is 2 min to obtain a uniform glue ball lens.

[0067] 4. Then, through the ICP etching process, select a suitable etching program based on the relationship between the glue ball and the etched surface height. Etching gas: SF6: 50 sccm, CF4: 30 sccm, H2: 5 sccm, O2: 6 sccm, ICP: 1500 W, RF: 500 W, pressure: 1 Pa, back purge helium pressure: 1 kPa, cooler temperature 0°C. The etching precisely transfers the glue ball surface profile to the silicon substrate;

[0068] 5. The completed first-side structure is integrated with the carrier through a temporary bonding method. The thickness of the bonding glue is 1.2 times the sag of the first-side lens, and then it is baked for 10 min at a temperature of 120°C. Finally, the wafer and the carrier are bonded at 200°C with a bonding pressure of 4 kN and a bonding time of 5 min using a bonding device to ensure good bonding strength.

[0069] 6. After the first bonding, the annealing temperature is 200°C and the time is 20 min.

[0070] 7. After annealing is completed, a secondary bonding process is carried out. The process conditions are 220 °C, the bonding pressure is 5 kN, and the bonding time is 10 min.

[0071] 8. Then, the second-side lens processing is completed according to the same process as in Steps 3 and 4. After bonding, good heat dissipation can be ensured, and the transfer etching of the second-side lens structure can be completed with high quality.

[0072] 9. After the structure is completed, debonding is carried out by thermal sliding at 250 °C, and finally, the residual bonding material is cleaned by soaking in NMP.

[0073] Comparative Example 1

[0074] This comparative example is generally the same as Example 1, and the main difference lies in:

[0075] The bonding process in Steps 5-7 is omitted, and instead, the wafer after constructing the first-side lens is directly supported by a bracket for the lithography and etching processes of the second side.

[0076] Finally, due to the poor heat dissipation during the etching process, the first-side lens with a convex structure will cause poor contact. In addition, for the main heat dissipation system, He gas, it cannot circulate and contact effectively. The heat energy accumulates during the etching process, and finally, it cannot dissipate heat in time. Photoresist carbonization and paste-like abnormalities appear at the top of the lens, and it also does not have the protective effect on the first-side lens that can be achieved after bonding, and it cannot prevent the lens surface from being scratched and soiled during the process. The micrograph of the obtained product is as Figure 4 shown.

[0077] Comparative Example 2

[0078] This comparative example is generally the same as Example 1, and the main difference lies in:

[0079] The processes of annealing and secondary bonding in Steps 6-7 are omitted, and instead, the preparation of the double-sided lens structure is directly based on the primary bonding.

[0080] Finally, due to the poor heat dissipation during the etching process, microbubbles will appear in the bonding glue during the primary bonding, which is prone to cause voids. Under some etching conditions (such as etching conditions with high heat accumulation), there will also be problems of poor heat dissipation. The micrograph of the defective product obtained is as Figure 5 shown; while in Example 1, after annealing and then carrying out secondary bonding, the problem of voids caused by bubbles is greatly reduced, thereby ensuring good system heat transfer between the lens structure, the bonding glue, and the carrier wafer, and avoiding the occurrence of the above problems to the greatest extent. The micrograph of the obtained product is as Figure 6 shown, which is significantly smoother and of better quality.

[0081] Example 2

[0082] This embodiment is generally the same as Embodiment 1, and the main difference lies in:

[0083] In Steps 3 and 8, reflux is achieved by hot plate heating, and the heating temperature is the same as that in Embodiment 1.

[0084] The contour deviation of the finally obtained lens structure is significantly higher than that in Embodiment 1. This shows that with the conventional hot plate reflux method, the balling of the photoresist is insufficient, the surface profile shows an M shape, with a depression in the middle and asymmetry on the left and right, and the PV value (representing the standard surface profile deviation) is about 100 nm, as specifically shown in Figure 7 shown; while with the preferred condensation reflux method provided by the present invention, the balling of the photoresist is sufficient, the surface profile curve is symmetric on the left and right, and the PV value is about 30 nm, as shown in Figure 8 shown.

[0085] Embodiment 3

[0086] This embodiment exemplifies the manufacturing process of a double-sided lens, which is specifically as follows:

[0087] 1. Use a double-polished silicon wafer with a thickness 10 μm larger than the theoretical product thickness. The theoretical product thickness is 500 μm, and a silicon wafer with a thickness of 510 μm is selected to compensate for the loss of sag caused by over-etching during the etching process.

[0088] 2. Complete the production of front and back mark markings through a conventional double-sided lithography and etching process; the double-sided marking points are used for subsequent single-sided lens lithography alignment.

[0089] 3. Fabricate a glue column on the silicon lens through a conventional lithography process, and then place the wafer in the Figure 3 provided new reflux system for vapor condensation cycle reflux. The reflux temperature is 95 °C, and the reflux time is 5 min to obtain a uniform glue ball lens.

[0090] 4. Then, through the ICP etching process, select an appropriate etching program based on the relationship between the glue ball and the surface height after etching. Etching gas: SF6: 50 sccm, CF4: 30 sccm, H2: 5 sccm, O2: 6 sccm, ICP: 1500 W, RF: 500 W, pressure: 1 Pa, backside purge helium pressure: 1 kPa, cooler temperature 0 °C, and transfer the surface profile of the glue ball to the silicon substrate accurately by etching;

[0091] 5. The completed first-side structure is integrated with the carrier wafer through a temporary bonding method. The thickness of the bonding glue is 1.1 times the sag of the first-side lens, and then bake for 10 min at a temperature of 120 °C. Finally, bond the wafer and the carrier wafer at 220 °C, with a bonding pressure of 2 kN and a bonding time of 10 min to ensure good bonding strength.

[0092] 6. After the first bonding, the annealing temperature is 230 °C and the time is 10 min.

[0093] 7. After completing the annealing, perform the second bonding process. The process conditions are 210 °C, the bonding pressure is 2 kN, and the bonding time is 10 min.

[0094] 8. Then complete the processing of the second-side lens according to the same process as in steps 3 and 4. After bonding, good heat dissipation can be ensured, and the transfer etching of the second-side lens structure can be completed with high quality.

[0095] 9. After completing the structure, debond at 260 °C by the thermal sliding method, and finally soak and clean the residual bonding material with NMP.

[0096] Example 4

[0097] This example illustrates the manufacturing process of a double-sided lens, which is specifically as follows:

[0098] 1. Use double-polished silicon wafers with a thickness 5 - 10 μm larger than the theoretical product thickness. The theoretical product thickness is 500 μm, and a silicon wafer with a thickness of 505 μm is selected to compensate for the loss of sag caused by over-etching during the etching process.

[0099] 2. Complete the production of front and back mark markings through the conventional double-sided photolithography and etching process; the double-sided marking points are used for subsequent single-sided lens photolithography alignment.

[0100] 3. Make glue columns on the silicon lens through the conventional photolithography process, and then place the wafer in Figure 3 the provided new reflux system for vapor condensation and circulation reflux. The reflux temperature is 90 °C and the reflux time is 4 min to obtain uniform glue ball lenses.

[0101] 4. Then, through the ICP etching process, select the appropriate etching program based on the relationship between the glue ball and the etched surface height. Etching gas: SF6: 50 sccm, CF4: 30 sccm, H2: 5 sccm, O2: 6 sccm, ICP: 1500 W, RF: 500 W, pressure: 1 Pa, backside purge helium pressure: 1 kPa, cooler temperature 0 °C. The etching precisely transfers the glue ball surface profile to the silicon substrate;

[0102] 5. The completed first-side structure is integrated with the carrier wafer through the temporary bonding method. The thickness of the bonding glue is 1.3 times the sag of the first-side lens, and then bake for 15 min at a temperature of 110 °C. Finally, bond the wafer and the carrier wafer at 210 °C with a bonding pressure of 6 kN and a bonding time of 8 min to ensure good bonding strength.

[0103] 6. After the first bonding, the annealing temperature is 220 °C and the time is 15 min.

[0104] 7. After annealing is completed, a secondary bonding process is carried out. The process conditions are 200 °C, the bonding pressure is 6 kN, and the bonding time is 8 min.

[0105] 8. Then, the second-side lens processing is completed according to the same process as in Steps 3 and 4. After bonding, good heat dissipation can be ensured, and the transfer etching of the second-side lens structure can be completed with high quality.

[0106] 9. After the structure is completed, debonding is carried out by thermal sliding at 245 °C, and finally, the residual bonding material is cleaned by soaking in NMP.

[0107] Based on the above embodiments and comparative examples, it can be clearly seen that the manufacturing method provided by the embodiments of the present invention utilizes the idea of temporary bonding to form a dense bond between the first microlens on the first side and the carrier plate through a bonding material, and changes the purging and cooling of the first side to the purging and cooling of the carrier plate. This can avoid the influence of the first microlens, especially the convex first microlens, on the purging of the cooling gas, improve the purging efficiency and uniformity of the cooling gas, and further avoid the problem of carbonization of some photoresist colloids caused by local temperature out of control, thereby avoiding the influence on the structure and appearance of the microlens on the second side, and significantly reducing the defect rate during mass production.

[0108] It should be understood that the above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for manufacturing a double-sided microlens structure, characterized in that: include: Providing a substrate having a first surface and a second surface disposed opposite to each other; The first surface is coated with photoresist and subjected to photolithography and reflow processes to form a first colloid; Performing pattern transfer etching on the first surface by using the first colloid to form a first microlens on the first surface; The first surface with the first microlens is bonded to the carrier by using a bonding material; the bonding process specifically includes the steps of primary bonding, annealing treatment and secondary bonding; the primary bonding is used to realize the first combination of the first surface and the carrier, the bonding pressure is removed during the annealing treatment and the temperature is used for treatment, and the bonding pressure is continuously applied during the secondary bonding, and the primary bonding specifically includes: applying the bonding material to the first surface with the first microlens to form a bonding adhesive layer, the thickness of the bonding adhesive layer is 1.1-1.3 times the height or depth of the first microlens, forming a bonding material layer after bonding and baking, and then making the bonding material layer adhere to the surface of the carrier for pressure bonding; The second surface is coated with photoresist and subjected to photolithography and reflow processes to form a second colloid; Performing pattern transfer etching on the second surface by using the second colloid to form a second microlens on the second surface, and applying forced cooling to the carrier during the etching process; The bonding between the first surface and the carrier is released to obtain a double-sided microlens structure.

2. The method according to claim 1, characterized in that: The temperature of the primary bonding and / or secondary bonding is 200-220°C, the time is 5-10min, and the pressure is 2-6kN; The annealing treatment is carried out at a temperature of 200-230 degrees and for a time of 10-20 minutes.

3. The method according to claim 1, characterized in that: The reflux process is carried out in a steam condensation cycle, and the steam condensation cycle specifically includes: The circulating liquid is heated to form vapor, and the lens structure to be processed by the reflow process is brought into contact with the vapor, so that the photoresist remaining after the photolithography process forms the first colloid or the second colloid under the action of its own surface tension.

4. The method according to claim 3, characterized in that: The circulating liquid includes ethanol and / or isopropanol diluted with water; the heating temperature of the steam condensation cycle is 80-100° C. and the time is 2-5 minutes.

5. The method according to claim 1, characterized in that: The debonding temperature of the bonding material is above 250°C.

6. The method according to claim 1, characterized in that: The carrier is selected from a silicon wafer, and the thickness of the carrier is greater than the designed thickness of the double-sided microlens structure by 5-10 um.

7. The manufacturing method according to claim 1, characterized in that: The forced cooling includes cooling by circulating coolant and synchronously purging with cooling gas.

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