Low-cost micron-scale resolution photoetching alignment device and method

Abstract

The invention relates to a low-cost micron-scale resolution photoetching alignment device and a low-cost micron-scale resolution photoetching alignment method. The device comprises a light source system, a microscope system, a high-elasticity film table and an XY theta displacement table, the light source system comprises a control panel and a control case electrically connected with the control panel, a plurality of LED lamp beads are arranged on the control panel in an array mode, each LED lamp bead is covered with a collimating lens, and a fan is further arranged on the control panel; the microscope system comprises a microscope support, a CCD camera, a variable-focus objective lens and an ocular lens, wherein the CCD camera, the variable-focus objective lens and the ocular lens are arranged on the microscope support. The XY theta displacement table is placed below the variable-focus objective lens and the ocular lens, and the high-elasticity film table is placed on the upper end face of the XY theta displacement table. The device disclosed by the invention is high in resolution and low in cost, the resolution and the overlay resolution can respectively reach 2 microns and 4 microns, and the cost of the whole set of equipment is lower than 80,000 RMB and is far lower than the pricing of photoetching machines on the market.

Description

Technical Field

[0001] This invention relates to a low-cost photolithography alignment device and method with micron-level resolution, belonging to the field of semiconductor micro-nano fabrication technology. Background Technology

[0002] Photolithography is an indispensable and crucial step in the manufacturing process of semiconductor devices, and the resolution of the photolithography process is a key indicator determining the size of semiconductor devices. Factors affecting pattern resolution mainly include the wavelength of the light source in the photolithography equipment, the collimation of the light source, the overlay alignment accuracy, the exposure dose, and the characteristics of the photoresist. Higher pattern resolution requirements significantly increase the corresponding equipment and material costs. For example, a 365nm wavelength photolithography machine can achieve a pattern resolution of 400nm, but its price is several million RMB; while the most advanced extreme ultraviolet (EUV) lithography machine can achieve a 3nm process, but its price is several hundred million RMB. Therefore, commercially available photolithography machines are prohibitively expensive for universities, research institutes, and small and medium-sized science and technology enterprises, requiring substantial research investment.

[0003] Currently, basic scientific research and many semiconductor companies do not have high requirements for lithography resolution. Although there are many lower-resolution devices available for semiconductor device manufacturing, such as laser direct writing equipment, electro-inking equipment, and imprinting equipment, lithography machines and their alignment devices remain the most efficient choice from a processing efficiency perspective. Therefore, designing and building low-cost lithography equipment will greatly reduce the research and production costs of semiconductor device micro- and nano-fabrication. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a low-cost photolithography alignment device and method with micron-level resolution. The photolithography resolution and overlay resolution can reach 2μm and 4μm respectively. The total cost of the equipment is less than 80,000 RMB, which is far lower than the market price of photolithography machines.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A low-cost photolithography alignment device with micron-level resolution includes: a light source system, a microscope system, a highly elastic film stage, and an XYθ displacement stage; The light source system includes a control board and a control cabinet electrically connected to the control board. The control board has an array of LED beads arranged in an array, and each LED bead is covered with a collimating lens. The control board is also equipped with a fan. The microscope system includes a microscope support and a CCD camera, a variable focus objective, and an eyepiece mounted on the microscope support. The XYθ displacement stage is placed below the variable focus objective and eyepiece, and the high elastic membrane stage is placed on the upper surface of the XYθ displacement stage.

[0006] The low-cost micron-level resolution photolithography alignment device, preferably, further includes a metal housing. During photolithography, the LED beads are placed vertically downwards above the metal housing, and the high-elasticity film stage and XYθ displacement stage are placed inside the metal housing. The metal housing is used to isolate the influence of external stray light and serves as a sample chamber.

[0007] Preferably, in the low-cost micron-level resolution photolithography alignment device, the inner surface of the metal shell is coated with a black coating and treated with diffuse reflection to prevent the light emitted by the LED beads from being refracted and scattered on the inner wall.

[0008] The low-cost micron-level resolution photolithography alignment apparatus, preferably, comprises a high-elasticity film stage consisting of a planar rigid carrier and a high-elasticity transparent film adhered to the planar rigid carrier.

[0009] Preferably, in the low-cost micron-level resolution photolithography alignment device, the highly elastic transparent film has grooves for supporting the substrate to be exposed.

[0010] In the aforementioned low-cost micron-level resolution photolithography alignment apparatus, preferably, the highly elastic transparent film is selected from one or more, including polydimethylsiloxane and hydrogenated styrene-butadiene block copolymer.

[0011] The low-cost micron-level resolution photolithography alignment device is preferably prepared by a leveling annealing film formation method. A high-elasticity transparent film prepolymer precursor solution is attached to the planar rigid carrier, allowed to stand and level, and the concentration of the precursor solution is adjusted according to the required thickness of the high-elasticity transparent film. After annealing, a high-elasticity film stage with a flat upper surface is obtained.

[0012] Preferably, in the low-cost, micron-level resolution photolithography alignment apparatus, the highly elastic transparent film has grooves for supporting the substrate to be exposed, and the thickness of the grooves should be consistent with the thickness of the substrate to be exposed, ensuring that the upper surface of the substrate to be exposed is flush with the upper surface of the highly elastic transparent film. Preferably, in the low-cost, micron-level resolution photolithography alignment apparatus, the emission angle of the LED beads is less than or equal to 2°.

[0013] Preferably, in the low-cost micron-level resolution photolithography alignment device, the emission wavelength of the LED beads includes any one of 436nm, 365nm, 254nm, 248nm, 193nm, or 172nm.

[0014] A second aspect of the present invention provides an operation method for the above-described photolithography alignment apparatus, comprising the following steps: S1: Photoresist is spin-coated onto the substrate to be exposed; S2: Prepare the highly elastic transparent film, place it above the planar rigid carrier to obtain the highly elastic film stage, and open a groove in the middle of the highly elastic transparent film so that the substrate to be exposed can be placed in it precisely; S3: Place the high-elasticity film stage onto the XYθ displacement stage, aim the microscope at the substrate to be exposed, and observe it with an eyepiece or computer. S4: After attaching sticky notes to the four corners of the photomask, place it above the highly elastic transparent film. With the aid of a microscope, move the photomask to align it with the pattern of the substrate to be exposed below. Then, press down on the photomask and pull out the sticky notes from the four corners. At this time, the air layer in the photomask and the highly elastic transparent film is expelled, and the two are tightly bonded together. The photomask is also tightly bonded to the upper surface of the substrate to be exposed. S5: Transfer the high-elasticity film stage, the substrate to be exposed, and the photomask from step S4 to the sample chamber of the light source system. Place the substrate to be exposed in the area directly below the LED lamp array. After setting the exposure time and exposure power in the control box, turn on the light source to complete the exposure. S6: Take out the high-elasticity film stage from step S5, remove the photomask and the exposed substrate, immerse the substrate in the developing solution for a certain time, rinse, blow dry and dry, and then observe the pattern under a microscope. Repeat the above operation when overlaying.

[0015] The present invention has the following advantages due to the adoption of the above technical solutions: 1. The device of the present invention has high resolution and low cost. The resolution and overlay resolution can reach 2μm and 4μm respectively. The total cost of the equipment is less than RMB 80,000, which is far lower than the price of lithography machines on the market. All materials used in the device of the present invention can be purchased and assembled at low cost.

[0016] 2. The device of this invention is small in size. Because the light source uses an LED lamp bead array, the light source system is compact. Commercial lithography machine light source systems need to reflect or refract light from a point source through various prisms to turn it into parallel light that illuminates the substrate to be exposed, resulting in a bulky system. The advantage of miniaturization is that it greatly reduces the space required for lithography equipment, which is a significant advantage for laboratories or small production plants.

[0017] 3. The device of the present invention is lightweight. The overall weight of the photolithography alignment device involved in the present invention does not exceed 40kg, making it easy to transport.

[0018] 4. The device of this invention has strong compatibility. The photolithography alignment device involved in this invention can be divided into a light source system and an alignment system. The alignment system is compatible with commercial metallurgical microscopes or other microscopic systems. In addition to photolithography requirements, the light source system can also be used for other experimental tasks such as photochemical reaction cells. Attached Figure Description

[0019] Figure 1 A schematic diagram of the light source system in the low-cost micron-level resolution photolithography alignment device provided by the present invention; Figure 2 A schematic diagram showing the relative positions of the microscope system, the high-elasticity film stage, and the XYθ displacement stage in the low-cost micron-resolution photolithography alignment device provided by the present invention. Figure 3 A schematic diagram of the highly elastic film stage groove and the substrate to be exposed in the low-cost micron-level resolution photolithography alignment device provided by the present invention; Figure 4 This is a photolithography effect diagram of Example 1, with a photolithography resolution of 2μm; The attached figures are labeled as follows: 1-Collimating lens; 2-LED lamp bead; 3-Control board; 4-Fan; 5-Control chassis; 6-Cable; 7-CCD camera; 8-Microscope stand; 9-Variable focus objective and eyepiece; 10-Substrate to be exposed; 11-Photolithography plate; 12-Note strip; 13-High elasticity film stage; 14-Planar rigid carrier; 15-XYθ displacement stage; 16-θ displacement stage knob; 17-θ displacement stage; 18-Y displacement stage; 19-X displacement stage; 20-X displacement stage knob; 21-Y displacement stage knob; 22-Metal casing. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," "third," "fourth," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0022] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0023] Currently, basic scientific research and many semiconductor companies do not have high requirements for lithography resolution. Although there are many lower-resolution devices available for semiconductor device manufacturing, such as laser direct writing equipment, electro-inking equipment, and imprinting equipment, lithography machines and their alignment devices remain the most efficient choice from a processing efficiency perspective. Therefore, designing and building low-cost lithography equipment will greatly reduce the research and production costs of semiconductor device micro- and nano-fabrication.

[0024] Based on the above-mentioned technical problems, the present invention provides a low-cost micron-level resolution photolithography alignment device, with photolithography resolution and overlay resolution reaching 2μm and 4μm respectively. The total cost of the device is less than 80,000 RMB, which is far lower than the price of photolithography machines on the market.

[0025] like Figure 1 , 2 As shown, the low-cost micron-level resolution photolithography alignment device involved in this invention includes: a light source system, a microscope system, a highly elastic film stage 13, and an XYθ displacement stage 15.

[0026] Specifically, the light source system includes a control board 3 and a control housing 5 electrically connected to the control board 3. Several LED beads 2 are arranged in an array on the control board 3, and each LED bead 2 is covered with a collimating lens 1. A fan 4 is also provided on the control board 3. The microscope system includes a microscope support 8 and a CCD camera 7, a variable focus objective lens, and an eyepiece 9 mounted on the microscope support 8. The XYθ displacement stage 15 is placed below the variable focus objective lens and the eyepiece 9, and the high elasticity film stage 13 is placed on the upper surface of the XYθ displacement stage 15.

[0027] The technical solution of the present invention will be described in detail below with reference to specific examples.

[0028] Example 1 The substrate 10 used in Example 1 below is a hard silicon wafer with alignment cross markings, the thickness of which is 0.5 mm, and the length and width of which are 2 cm × 2 cm. The photoresist used in Example 1 is AZ5214 (a known photoresist).

[0029] Specifically, such as Figure 1 , 3 As shown, the light source system includes a 365nm LED array 2, a collimating lens 1, a control board 3, and a fan 4. The 365nm LEDs 2 are fixed on the control board 3 in a matrix arrangement, with 15 LEDs per row and 15 LEDs per column, with a spacing of 0.8cm between the LEDs. Each LED is embedded in the control board 3, and a collimating lens 1 is mounted on top of each LED, with an emission angle of 2°. The fan 4 is also fixed on the control board 3. When the LEDs 2 are working, the fan automatically runs to cool them. The LEDs 2 are placed vertically downwards above a square metal casing 22. The metal casing 22 serves to isolate stray light and act as a sample chamber. The dimensions of the metal casing 22 are 15cm (length) × 15cm (width) × 5cm (height). The metal casing 22 must be horizontally and vertically aligned to ensure that the LEDs 2 at the top of the light source are facing vertically downwards. The inner surface of the metal casing 22 is covered with a black coating for diffuse reflection, preventing the light emitted by the LED beads 2 from being refracted and scattered on the inner wall. The control box 5 is connected to the light source via a cable, and the control box 5 can set the luminous power and exposure time of the LED beads 2. Of course, the emission wavelength of the LED beads 2 can be any band, including commonly used ones such as 436nm, 365nm, 254nm, 248nm, 193nm, and 172nm.

[0030] like Figure 2 As shown, the microscope system includes a variable focus objective and eyepiece 9, a CCD camera 7, and a microscope support 8. The variable focus objective and eyepiece 9 are mounted on the microscope support 8, and the CCD camera 7 is mounted on the variable focus objective and eyepiece 9. The XYθ displacement stage 15 is placed below the microscope tube. The high elasticity film stage 13 is placed on the upper surface of the XYθ displacement stage 15.

[0031] like Figure 2As shown, the function of the high-elasticity stage 13 is to tightly attach the photomask 11 above the substrate 10 to be exposed. The high-elasticity stage 13 consists of a planar rigid carrier at the bottom and a high-elasticity transparent PDMS film. The planar rigid carrier serves as the bearing medium, and the high-elasticity transparent PDMS film is adhered to the planar rigid carrier. A groove is located in the center of the high-elasticity transparent PDMS film, the shape and size of which are identical to those of the substrate 10 to be exposed, allowing the substrate 10 to be placed precisely within the groove. The thickness of the high-elasticity transparent PDMS film is strictly identical to the thickness of the substrate 10 to be exposed.

[0032] Furthermore, the material of the highly elastic transparent film can be selected from one or more of polydimethylsiloxane (PDMS), hydrogenated styrene-butadiene block copolymer (SEBS), etc.

[0033] A second aspect of the present invention provides an operation method for the above-described photolithography alignment apparatus, comprising the following steps: Step 1: Spin-coat photoresist onto the silicon wafer at a speed of 2000 rpm for 60 seconds. Pre-baking temperature is 110℃ for 1 minute.

[0034] Step 2: Prepare a 15cm (length) × 15cm (width) × 0.5mm (height) high-elasticity transparent PDMS film and place it on top of a 15cm (length) × 15cm (width) × 0.5mm (height) flat stainless steel plate to obtain a high-elasticity film stage 13. Cut a 2cm (length) × 2cm (width) × 0.5mm (height) groove in the middle of the PDMS high-elasticity transparent film so that the substrate 10 to be exposed can be placed precisely within it.

[0035] Step 3: Place the high-elasticity membrane stage 13 from Step 2 onto the XYθ displacement stage 15, align the microscope tube with the substrate to be tested, and observe it using computer software.

[0036] Step 4: Attach thin, easily removable sticky notes 12 to the four corners of the photomask 11. Place the photomask 11 on top of the highly elastic transparent PDMS film. With the aid of a microscope, move the photomask 11 to align it with the pattern on the substrate 10 to be exposed below. Then, gently and evenly press down on the photomask 11 and remove the sticky notes 12 from the four corners. This removes the air layer between the photomask 11 and the highly elastic transparent PDMS film, causing them to adhere tightly together. At this point, the photomask 11 also adheres tightly to the upper surface of the central substrate 10 to be exposed.

[0037] Step 5: Carefully transfer the high-elasticity stage 13, the substrate to be exposed 10, and the photomask 11 from Step 4 into the sample chamber of the light source system. Place the substrate to be exposed 10 directly below the LED bead array. Set the exposure time to 4s and the exposure power to 30mW on the control panel of the control box 5, and then turn on the light source to complete the exposure.

[0038] Step 6: Remove the high-elasticity film stage 13 from Step 5, remove the photomask 11, and remove the exposed substrate. Immerse in TMAH developer, develop for 10 seconds, rinse with water twice and dry with nitrogen, then bake at 110°C for 1 minute.

[0039] Step 7: Observe the pattern under a microscope and repeat the above operation when engraving.

[0040] Experimental results are as follows Figure 4 As shown, after exposure of the photoresist using the photolithography alignment apparatus provided by this invention, a pattern with a linewidth of 2μm and clear pattern edges can be obtained. Furthermore, the low-cost, micron-level resolution photolithography alignment apparatus of this invention has an overlay resolution of 4μm.

[0041] The device of the present invention has the following advantages: 1. The device of this invention boasts high resolution and low cost, achieving resolutions of 2μm and 4μm for overlay and overlay respectively. The total cost of the equipment is less than 80,000 RMB, significantly lower than the market price of lithography machines. All materials used in this device can be purchased and assembled at low cost. 2. The device is compact. Due to the use of an LED array as the light source, the light source system is small. Commercial lithography machine light source systems require reflecting or refracting light from a point source through various prisms to create parallel light that illuminates the substrate 10 to be exposed, resulting in a bulky system. Miniaturization greatly reduces the space required for lithography equipment, a significant advantage for laboratories or small production plants. 3. The device is lightweight. The overall weight of the lithography alignment device involved in this invention does not exceed 40kg, facilitating transport. 4. The device is highly compatible. The lithography alignment device involved in this invention can be divided into a light source system and an alignment system. The alignment system is compatible with commercial metallurgical microscopes or other microscopic systems. In addition to lithography requirements, the light source system can also be used for other experimental tasks such as photochemical reaction cells.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-cost photolithography alignment device with micron-level resolution, characterized in that, include: Light source system, microscope system, high elastic membrane stage (13) and XYθ displacement stage (15); The light source system includes a control board (3) and a control box (5) electrically connected to the control board (3). A number of LED beads (2) are arranged in an array on the control board (3). Each LED bead (2) is covered with a collimating lens (1). A fan (4) is also provided on the control board (3). The microscope system includes a microscope stand (8) and a CCD camera (7), a variable focus objective, and an eyepiece (9) mounted on the microscope stand (8). The XYθ displacement stage (15) is placed below the variable focus objective and eyepiece (9), and the high elasticity film stage (13) is placed on the upper surface of the XYθ displacement stage (15).

2. The low-cost micron-level resolution photolithography alignment apparatus according to claim 1, characterized in that, The photolithography alignment device also includes a metal housing (22). During photolithography, the LED beads (2) are placed vertically downward above the metal housing (22). The high elasticity film stage (13) and the XYθ displacement stage (15) are placed inside the metal housing (22). The metal housing (22) is used to isolate the influence of external stray light and serves as a sample chamber.

3. The low-cost micron-level resolution photolithography alignment apparatus according to claim 2, characterized in that, The inner surface of the metal casing (22) is coated with a black coating and treated with diffuse reflection to prevent the light emitted by the LED beads (2) from being refracted and scattered on the inner wall.

4. The low-cost micron-level resolution photolithography alignment apparatus according to claim 3, characterized in that, The high-elasticity membrane platform (13) consists of a planar rigid carrier (14) and a high-elasticity transparent membrane adhered to the planar rigid carrier (14).

5. The low-cost micron-level resolution photolithography alignment apparatus according to claim 4, characterized in that, The highly elastic transparent film has grooves for supporting the substrate (10) to be exposed.

6. The low-cost micron-level resolution photolithography alignment apparatus according to claim 5, characterized in that, The highly elastic transparent film is selected from one or more, including polydimethylsiloxane and hydrogenated styrene-butadiene block copolymer.

7. The low-cost, micron-level resolution photolithography alignment apparatus according to claim 6, characterized in that, The high-elasticity transparent film is prepared by leveling annealing film formation method, that is, the high-elasticity transparent film prepolymer precursor solution is attached to the planar rigid carrier (14), and allowed to stand and level. The concentration of the high-elasticity transparent film prepolymer precursor solution is adjusted according to the required thickness of the high-elasticity transparent film. After annealing, a high-elasticity film stage with a flat upper surface can be obtained.

8. The low-cost micron-level resolution photolithography alignment apparatus according to claim 7, characterized in that, The emission angle of the LED bead (2) is less than or equal to 2°.

9. The low-cost micron-level resolution photolithography alignment apparatus according to claim 8, characterized in that, The emission wavelength of the LED beads (2) includes any one of 436nm, 365nm, 254nm, 248nm, 193nm or 172nm.

10. A method of operating the photolithography alignment apparatus according to any one of claims 4-9, characterized in that, Includes the following steps: S1: Photoresist is spin-coated onto the substrate (10) to be exposed; S2: Prepare the high-elasticity transparent film and place it above the planar rigid carrier (14) to obtain the high-elasticity film stage (13). Make a groove in the middle of the high-elasticity transparent film so that the substrate (10) to be exposed can be placed in it. S3: Place the high elasticity film stage (13) on the XYθ displacement stage (15), point the microscope at the substrate (10) to be exposed, and observe it with an eyepiece or computer; S4: After attaching sticky notes (12) to the four corners of the photomask (11), place it above the highly elastic transparent film. With the aid of a microscope, move the photomask (11) to align it with the pattern of the substrate (10) to be exposed below. At this time, press down on the photomask (11) and pull out the sticky notes (12) at the four corners. At this time, the air layer in the photomask (11) and the highly elastic transparent film is discharged, and the two are tightly attached together. The photomask (11) is also tightly attached to the upper surface of the substrate (10) to be exposed. S5: Transfer the high elasticity film stage (13), the substrate to be exposed (10), and the photomask (11) from step S4 to the sample chamber of the light source system. Place the substrate to be exposed (10) directly below the LED lamp bead (2) array. After setting the exposure time and exposure power in the control box (5), turn on the light source to complete the exposure. S6: Take out the high elasticity film stage (13) from step S5, remove the photomask (11) and the exposed substrate, immerse the substrate in the developing solution for a certain time, rinse, blow dry and dry, and then observe the pattern under a microscope. Repeat the above operation when overlaying.

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