Apparatus and method for manufacturing an elastomeric stamp

Abstract

The application relates to the technical field of nano-imprinting, in particular to a preparation device and method of an elastomer imprint head, which comprises a base, a silicon wafer, a silica gel pad, a metal positioning sheet, a quartz sheet and a top cover; a vacuum is used to adjust the silicon wafer protrusion to form a central convex surface of the imprint head, and an ultraviolet curing process is combined to prepare the elastomer imprint head with specific curvature. The imprint head is attached from the center to the edge to discharge air bubbles during imprinting, and the edge is preferentially separated to reduce the demolding force during demolding, so that the semiconductor step-by-step process is adapted, and the yield is improved to more than 98%. The technical advantage of the application is that the step-by-step imprint manufacturing process is compatible, and the special contact and demolding mode can effectively reduce the defects in the imprint structure and improve the yield.

Description

Technical Field

[0001] This invention relates to the field of nanoimprint technology, specifically to an apparatus and method for preparing an elastomer imprint head. Background Technology

[0002] Nanoimprinting is a micro-nano fabrication process that has been an alternative to photolithography since its inception. Existing imprinting heads cannot effectively remove air bubbles and are difficult to demold. Due to their typically large size, they cannot be applied to the semiconductor field.

[0003] Existing patent CN105607415A, which discloses "a nanoimprint head and an imprinting device having the nanoimprint head," reveals an imprint head design scheme for nanoimprinting. Specifically, in the nanoimprint head provided by this invention, by setting elastic elements between the load-bearing bracket and the template suction cup, the load-bearing bracket, which moves under the action of a motor, can uniformly transmit pressure to the template suction cup through at least three elastic elements during the downward pressing process, thereby improving the imprinting effect and imprinting performance.

[0004] Patent CN216286148U discloses an "Adaptive Imprint Head for Large-Area Nanoimprinting," which describes a design scheme for an adaptive imprint head used in large-area nanoimprinting. Specifically, this adaptive imprint head for large-area nanoimprinting can increase the efficiency of manual work and improve the overall convenience by allowing workers to easily view the internal working conditions and conveniently place objects onto the worktable.

[0005] Nanoimprint lithography is widely used in the production of optical and electronic devices and is currently being used in both academia and industry. Generally, while substrate materials, such as silicon wafers, quartz glass sheets, and metal sheets, have extremely smooth surfaces in the short term, unevenness is unavoidable over long distances. Therefore, traditional "plate-to-plate" imprinting methods require extremely high imprinting forces to ensure complete adhesion between the template and the substrate. This has led to the development of elastomeric composite templates. However, when applied to imprinting equipment, planar elastomeric composite templates present problems such as incomplete air bubble removal during bonding and excessive demolding force during demolding.

[0006] The issues are summarized as follows:

[0007] Residual bubbles: Bubbles are easily formed when the planar imprint head comes into contact with the substrate, leading to defects in the imprint structure;

[0008] Demolding is difficult: hard demolding requires a great deal of external force, which can easily damage the micro- and nano-structures;

[0009] Size limitations: Traditional imprint heads are too large to be adapted to semiconductor wafer-level processing.

[0010] Therefore, in response to the above problems, this technical solution proposes a device and method for preparing an elastomer imprint head. Summary of the Invention

[0011] The purpose of this invention is to provide an apparatus and method for preparing an elastomer imprint head, so as to solve the problems mentioned in the background art.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] An apparatus for preparing an elastomer imprint head includes a base, a silicone pad, a metal positioning plate, a quartz plate, and a top cover;

[0014] The base is made of metal, with air vents on the side walls for connecting a vacuum pump. A cylindrical through hole is located in the center, and grooves with a diameter larger than the cylindrical through hole are provided on the base around the cylindrical through hole. A silicon wafer is fitted and fixed in the groove. The connected vacuum pump draws air to a vacuum, causing the silicon wafer to bulge. The air vents are connected to the vacuum pump and also to a vacuum proportional valve, which accurately controls the degree of air evacuation.

[0015] The silicone pad has a square opening in the center, which contacts the silicon wafer to form an elastic support, used to limit the casting range of the elastomer;

[0016] The metal positioning plate has a square opening in the center that is larger than the size of the silicone pad, which is used to position the quartz plate and form a casting cavity.

[0017] The quartz plate is placed inside the opening of the metal positioning plate, serving as a template for the curing of the elastomer;

[0018] The top cover is made of metal and features a stepped through-hole design in the center. The lower hole is for fitting a quartz plate, while the upper hole is enlarged to accommodate the cured elastomer. It is also fixed to the base with screws.

[0019] Quartz glass is made of a light-transmitting material and is used for UV curing.

[0020] The manufacturing process of the elastic imprint head is as follows:

[0021] Place the silicon wafer in the groove of the base, turn on the vacuum pump, and the silicon wafer will bulge slightly downward due to atmospheric pressure. Then, control the vacuum level in the groove by controlling the value of the vacuum proportional valve, thereby controlling the height of the silicon wafer bulge.

[0022] Place the silicone pad tightly against the silicone wafer, and then place the metal positioning piece tightly against the silicone.

[0023] Cast the UV-cured elastomer, then cover it with a quartz sheet and press the top cover tightly. Then, screws are passed through the screw holes on the top cover, metal positioning plate, silicone pad and base from top to bottom and tightened.

[0024] Expose the device by shining a UV lamp from above. After the UV-cured elastomer adhesive has cured, peel it off layer by layer to obtain the elastomer imprint head.

[0025] Compared with the prior art, the beneficial effects of the present invention are: the present invention solves the problems of air bubbles easily remaining during bonding and defects easily caused during demolding by preparing an elastic imprint head with a convex surface;

[0026] By designing a method for fabricating a convex elastomer imprint head, in the subsequent imprinting process, as the imprint head is bonded to the substrate, it first bonds from the central convex part of the elastomer imprint head and then gradually diffuses to the surrounding area, which can effectively prevent air bubbles from remaining between the imprinting adhesive and the template.

[0027] By pressing the arc-shaped protrusion of the impression head against the template under force during demolding, the demolding is completed by first demolding the periphery and then gradually spreading inward, and finally separating with the center. This can greatly reduce the demolding force, and this demolding method can protect the solidified micro-nano structure from damage caused by hard demolding. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a device for preparing an elastomer imprint head.

[0029] Figure 2 This is a schematic diagram of the base structure in a device for preparing an elastomer imprint head.

[0030] Figure 3 This is a schematic diagram of the top cover in a device for preparing an elastomer impression head.

[0031] Figure 4 This is a schematic diagram of the structure of an imprint head in an apparatus for preparing an elastomer imprint head.

[0032] The components include: base 1, air vent interface 101, cylindrical through hole 102, groove 103, silicon wafer 2, silicone pad 3, metal positioning plate 4, quartz plate 5, top cover 6, cured elastomer 7, and quartz glass 8. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Please see Figures 1-4 An apparatus for preparing an elastomer impression head includes a base 1, a silicone pad 3, a metal positioning sheet 4, a quartz sheet 5, and a top cover 6.

[0038] The base 1 is made of metal, and the side wall has an air vent 101 for connecting a vacuum pump. A cylindrical through hole 102 is opened in the center. Around the cylindrical through hole 102, the base 1 has a groove 103 with a diameter larger than the cylindrical through hole 102. A silicon wafer 2 is fitted and fixed in the groove 103. The connected vacuum pump draws air to a vacuum, causing the silicon wafer 2 to bulge. The air vent 101 is connected to the vacuum pump and is also connected to a vacuum proportional valve. Under the control of the vacuum proportional valve, the degree of air evacuation is accurately controlled.

[0039] The silicone pad 3 has a square opening in the center, which contacts the silicon wafer 2 to form an elastic support, used to limit the casting range of the elastomer;

[0040] The metal positioning plate 4 has a square opening in the center that is larger than the size of the silicone pad, which is used to position the quartz plate 5 to form a casting cavity;

[0041] Quartz plate 5 is placed inside the opening of the metal positioning plate as an elastomer curing template;

[0042] The top cover 6 is made of metal and features a stepped through-hole design in the center. The lower hole is adapted to the quartz plate 5, while the upper hole is enlarged to accommodate the cured elastomer 7 and is fixed to the base with screws.

[0043] Quartz glass 8 is made of a light-transmitting material and is used for UV curing.

[0044] The manufacturing process of the elastic imprint head is as follows:

[0045] Place the silicon wafer 2 in the groove 103 of the base, turn on the vacuum pump, and the silicon wafer 2 will bulge slightly downward due to atmospheric pressure. Then, control the vacuum level in the groove 103 by controlling the value of the vacuum proportional valve, thereby controlling the height of the silicon wafer bulge.

[0046] Place the silicone pad 3 tightly against the silicone wafer 2, and then place the metal positioning piece 4 tightly against the silicone 2;

[0047] Cast the UV-cured elastomer 7, then cover it with the quartz sheet 5 and press the top cover 6 tightly. Then, use screws to pass through the screw holes on the top cover 6, the metal positioning piece 4, the silicone pad 3 and the base 1 from top to bottom and tighten them.

[0048] Expose the device by shining a UV lamp from above. After the UV-cured elastomer adhesive has cured, peel it off layer by layer to obtain the elastomer impression head (e.g., Figure 4 (As shown).

[0049] In this embodiment of the invention, the silicon wafer 2 is generally a 4-inch type commonly found on the market. When the silicon wafer 2 is placed in the groove 103, its polished surface faces upward.

[0050] It should be noted that, in order to adapt to different application requirements, the appropriate process can be switched to match the application scenario by changing the Young's modulus of the elastomer, the thickness of the silicone pad, the thickness of the quartz sheet, and the size of the silicone pad opening.

[0051] In a preferred embodiment of the present invention, the depth of the groove 103 is set to 0.5-2mm, and its diameter matches the size of the silicon wafer 2 (4 / 6 / 8 / 12 inches, etc.). At the same time, the vacuum proportional valve has a dynamic adjustment range of vacuum degree of -10kPa to -100kPa, with an accuracy of ±0.1kPa.

[0052] The cylindrical through-hole 102 has a diameter of 5-20mm, which serves as an airflow channel and also restricts the protrusion area of ​​the silicon wafer.

[0053] The inner wall of the groove 103 is provided with an annular air channel with a width of 0.1-0.5mm and a depth of 0.05-0.2mm, which is used to improve the uniformity of vacuum adsorption. The annular air channel is formed by laser processing and has a surface roughness Ra≤0.1μm.

[0054] In a preferred embodiment of the present invention, the silicone pad 3 is made of fluororubber, and its temperature resistance range is -40° to 200°.

[0055] When designing the stepped holes of the top cover 6, the lower hole diameter matches the diameter of the quartz plate 5 (tolerance ±0.01mm) to ensure that there is no elastomer leakage during the curing process;

[0056] The upper pore size is enlarged to 1.2-1.5 times that of the lower pore size to accommodate the expansion of the elastomer (with matching thermal expansion coefficients).

[0057] The UV curing process in step (4) is carried out in two stages:

[0058] First stage: Low-strength curing (10-30mW / cm²), time 60-180s, to avoid thermal stress accumulation;

[0059] Second stage: High-strength curing (50-100mW / cm²), time 10-30s, to ensure complete cross-linking.

[0060] As a preferred embodiment of the present invention, the mathematical model of the imprint head manufacturing process is as follows:

[0061] Vacuum-PV curve: Relationship between silicon wafer bump height h and vacuum level P:

[0062]

[0063] Where r is the radius of silicon wafer 2 and D is the bending stiffness; the accuracy of h value is ±1μm through closed-loop control.

[0064] Elastomer curing shrinkage compensation:

[0065] The relationship between the theoretical radius of curvature R0 of the imprint head and the actual value R is as follows:

[0066]

[0067] in, The coefficient of thermal expansion of the elastomer. For curing temperature rise;

[0068] The height of the silicon wafer bumps is adjusted in reverse using a pre-compensation algorithm.

[0069] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An apparatus for preparing an elastomeric stamping head, characterized by, The utility model provides a silicon wafer embossing device, including base (1), silicon wafer (2), silica gel pad (3), metal positioning sheet (4), quartz sheet (5) and top cover (6), base (1) adopts metal material, and the side wall is provided with air hole interface (101), is used for connecting vacuum pump, and the center is provided with cylindrical through -hole (102), and the cylindrical through -hole (102) is provided with recess (103) of the diameter greater than the cylindrical through -hole (102) on the corresponding base (1) around, and silicon wafer (2) is fixed with the recess (103) in adaptation, and the recess (103) inner wall is equipped with annular air passage, and through the vacuum pump connected air exhaust to vacuum makes silicon wafer (2) convex, and air hole interface (101) connects vacuum pump simultaneously still connects the vacuum proportional valve that is provided, and through control the vacuum pump and the vacuum proportional valve are extracted in -10kPa~-100kPa's vacuum degree range, to control silicon wafer (2) convex height, The silica gel pad (3) is provided with a square opening in the center to contact the silicon wafer (2) to form elastic support and limit the pouring range of the elastomer. The metal positioning sheet (4) is provided with a square opening in the center larger than the opening of the silica gel pad (3) to position and cooperate with the quartz sheet (5) to form a pouring cavity. The top cover (6) is designed with a stepped through hole in the center, the lower hole is adapted to the quartz sheet (5), and the diameter ratio of the lower hole to the upper hole is 1:1.2~1:1.5, and the upper hole is enlarged to accommodate the elastomer during curing, and the top cover (6) is fixed to the base (1) by screws.

2. An apparatus for making an elastomeric stamping head as in claim 1, wherein, The silica gel pad (3) is made of fluororubber and has a temperature resistance range of -40~200℃.

3. An apparatus for making an elastomeric stamping head as in claim 1, wherein, The annular air passage in the inner wall of the recess (103) has a width of 0.1-0.5mm, a depth of 0.05-0.2mm, and a surface roughness Ra≤0.1μm.

4. A method of manufacturing the elastomeric stamp of any one of claims 1-3 using the apparatus of claim 4. The method comprises the following steps: Place the silicon wafer (2) in the recess (103) of the base, start the vacuum pump, and the silicon wafer (2) is slightly convex downward due to atmospheric pressure, and the height of the convex silicon wafer (2) is controlled by controlling the vacuum proportional valve to extract air in the range of -10kPa~-100kPa with an accuracy of ±0.1kPa; Place the silica gel pad (3) closely against the silicon wafer (2), and then place the metal positioning sheet (4) closely against the silica gel pad (3); Pour the ultraviolet curing elastomer (7), then cover the quartz sheet (5) and press the top cover (6), then use screws to pass through the screw holes of the top cover (6), the metal positioning sheet (4), the silica gel pad (3), and the base (1) from top to bottom in sequence and tighten them; Use an ultraviolet exposure lamp to irradiate ultraviolet light from above to cure the elastomer, and the ultraviolet curing is carried out in two stages: the first stage is low intensity 10-30mW / cm² for 60-180s, and the second stage is high intensity 50-100mW / cm² for 10-30s, and after curing, the elastomer stamping head is obtained by peeling off layer by layer.

5. An elastomeric stamping head characterized by, The elastomer stamping head prepared by the method of claim 4 has a convex structure in the central region and a smaller edge thickness than the central thickness.

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