A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask

Abstract

The present invention discloses a method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask. By dividing patterns larger than 1 micron and patterns smaller than 1 micron, laser direct writing exposure and electron beam exposure are performed respectively. A double exposure plus stripping method is adopted. This method can accommodate both large line widths larger than micron level and small line widths at nanometer level within the pattern, and can process nanometer-scale fine patterns quickly and at low cost. In addition, a stripping method is adopted to transfer the photolithographic pattern to the material layer, which can avoid line width loss caused by etching and enable more accurate pattern transfer.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing and transferring micro-nano patterns, and in particular to a method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask. Background Art

[0002] In modern semiconductor manufacturing for integrated circuits, shrinking manufacturing nodes and the diverse demands of various specialized sub-sectors are driving the need for increasingly complex, refined, and diverse nanopatterns. Examples include the diverse shapes of nanopillars in optical instruments, the complex device shapes of MEMS, and the shapes of resonator interdigitated electrodes in surface acoustic wave devices. These micro-nano patterns can often feature lines with significantly different sizes, with both micron- and nanometer-scale lines coexisting within the desired pattern.

[0003] While using only one lithography method to create this pattern, such as electron beam lithography, offers high precision, often reaching 10nm, its exposure efficiency is very slow. Using this refined lithography method to create large-scale, micron-scale patterns over large areas often results in a waste of time and performance. Laser direct write lithography systems, on the other hand, are micron-scale lithography systems characterized by fast exposure speeds and resolutions above microns.

[0004] The existing technology uses a two-step photolithography + etching method for pattern transfer. This method uses laser direct writing + etching and electron beam exposure + etching methods. The large and small line width patterns in the pattern are photolithographically and etched twice. The photolithography generates the pattern, and the etching achieves the effect of pattern transfer. However, in the photolithography part of this method, if high-precision electron beam exposure is used to create large-scale patterns at the micron level, the exposure time will be long and the exposure efficiency will be low due to the problem of electron beam exposure speed, which greatly increases the cost. In the pattern transfer step after photolithography development, in order to transfer the photoresist pattern to a specific material (metal, semiconductor, insulator, etc.), the etching method is used to transfer the pattern, which often results in a wider line width after the pattern transfer, that is, a dimensional widening effect. This distortion of the pattern after transfer affects the device performance. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a high-precision, high-efficiency, low-cost method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask.

[0006] Technical solution: The present invention provides a method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask, comprising the following steps:

[0007] (1) using an organic solvent to clean the substrate material, spin-coating a photoresist on the substrate surface, and baking;

[0008] (2) introducing a pattern into a laser direct writing device, performing laser direct writing exposure on a substrate material, and obtaining a pattern larger than 1 micron by exposure; performing development using a developer, removing the exposed photoresist, and obtaining a developed substrate material;

[0009] (3) using a thin film growth method selected from electron beam evaporation, magnetron sputtering, or atomic layer deposition to coat the developed substrate material to obtain a coated substrate material;

[0010] (4) Soaking the coated substrate material in a water bath of etching solution to heat it, separating the substrate material from the film layer, and peeling and transferring the photolithographic pattern to the film layer to obtain a pattern above the micron level;

[0011] (5) spin coating a photoresist on the surface of the substrate material separated in step (4) and baking;

[0012] (6) introducing a pattern into an electron beam exposure device, performing electron beam exposure on the substrate material, aligning the overlay mark, and exposing to obtain a pattern with a line width of less than 1 micron; developing the pattern with a developer to remove the exposed photoresist and obtain a substrate material after secondary development;

[0013] (7) using a thin film growth method selected from electron beam evaporation, magnetron sputtering, or atomic layer deposition to coat the substrate material after secondary development to obtain a substrate material after secondary coating;

[0014] (8) The substrate material after secondary coating is immersed in a corrosive solution and heated in a water bath to separate the substrate material and the film layer, and the photolithographic pattern is peeled off and transferred to the film layer to obtain a nanoscale pattern.

[0015] Wherein, in step (1), the organic solvent cleaning is to sequentially place the substrate in acetone and isopropyl alcohol for ultrasonic cleaning for 5 to 10 minutes, the photoresist is a photosensitive photoresist, and the substrate material is a silicon semiconductor or silicon oxide with a conductive film, or a sapphire insulator; the spin coating is specifically to use an initial rotation speed of 500 to 700 rpm for 5 to 10 seconds and a subsequent rotation speed of 1000 to 5000 rpm for 30 to 40 seconds; the baking temperature is 100 to 180° C. and the time is 70 to 120 seconds, preferably 90 seconds.

[0016] Wherein, in step (2), the exposure dose is 10-100 mJ / cm 2 ; The developer is a photosensitive photoresist developer, and the developing time is 25 to 45 seconds.

[0017] In step (3), the coating is made of a material selected from metals, semiconductors, and insulators; specifically, other semiconductor materials such as polycrystalline silicon and single-crystal silicon, other insulating materials such as silicon oxide and silicon nitride, and other metal materials such as titanium and gold. The material layer may be a single layer or multiple layers.

[0018] Wherein, in step (5), the photoresist is an electron beam photoresist; the spin coating is specifically performed by using an initial rotation speed of 500-700 rpm for 5-10 seconds and a subsequent rotation speed of 1000-5000 rpm for 30-40 seconds; the baking temperature is 160-180°C and the time is 70-120 seconds, preferably 90 seconds.

[0019] Wherein, in step (6), the exposure dose is 100-500uC / cm 2 ; The developer is an electron beam photoresist developer, and the development time is 90 to 150 seconds; preferably 120 seconds.

[0020] Wherein, in step (4) or (8), the etching solution is one of acetone or N-methylpyrrolidone solution, and the water bath heating is performed at a temperature of 50 to 70° C. for 2 to 24 hours, preferably at 70° C. for 12 hours.

[0021] Principle of the invention: The present invention proposes a technology of performing two photolithography exposures and stripping for patterns with different line widths in micro-nano manufacturing to solve this problem. The pattern is divided into two layers, one larger than 1 micron and the other smaller than 1 micron, and the classification can be performed using the GDS file format. In the first step, a laser direct write photolithography method is used to manufacture patterns larger than 1 micron, and then a stripping method is used to manufacture the required partial micron patterned material. In the second step, an electron beam exposure method is used for overlaying to expose a pattern smaller than 1 micron, and electron beam evaporation and stripping are performed to manufacture the remaining nano-patterned material. The present invention adopts photolithography exposure followed by film coating, and finally adopts a stripping method for photolithography pattern transfer, which can perfectly avoid the problem of poor pattern transfer effect caused by etching the photolithography pattern. At the same time, the present invention adopts the method of laser direct write exposure + electron beam exposure, which does not require a photolithography mask, and can reduce manufacturing costs and exposure errors caused by the photolithography plate.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] (1) The double exposure plus stripping method can accommodate both large line widths (above micrometer level) and small line widths (nanometer level) within the pattern, thus avoiding the performance waste when using electron beam exposure for large-area, large-size patterns; (2) The preparation process does not require a photolithography mask, is low-cost, overcomes the exposure error of the photolithography plate, and avoids distortion after the etched pattern is transferred. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A brief flow chart of the present invention;

[0025] Figure 2 A planar pattern designed for the method of the present invention;

[0026] Figure 3 This is an actual plan view of the micro-nano pattern produced according to an embodiment of the present invention;

[0027] Figure 4 This is a cross-sectional view of a micro-nano pattern produced according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below with reference to the examples. The test materials used in the examples can all be purchased through conventional channels.

[0029] Example 1

[0030] A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask specifically comprises the following steps:

[0031] In terms of pattern design, the pattern lines should be divided into two parts: one larger than 1 micron and one smaller than 1 micron. Here, the pattern part larger than 1 micron is called a micron pattern, and the pattern smaller than 1 micron is called a nano pattern. Figure 2 As shown, it is an example of the classification method involved in the present invention, wherein the pattern outside the black frame is pattern one, and the line width is greater than 1 micron, and the pattern inside the black frame is pattern two, and the line width is less than 1 micron; after the two parts of the pattern are designed, an electron beam alignment mark is added to facilitate subsequent overlay.

[0032] (1) In terms of sample preparation, the following steps are completed at room temperature unless otherwise specified:

[0033] The substrate material is organically cleaned. The substrate material is sapphire with a conductive film. The sample is placed in acetone and isopropyl alcohol for ultrasonic cleaning for about 5 minutes to remove surface impurities. The sample is then placed in a spun-coater and vacuumed. AZ series photoresists, including positive and negative photoresists, are used, specifically AZ5214 photoresists. The photoresist is sucked into a dropper and dripped onto the sample. An initial speed of 500 rpm is used for spun-coating for 5 seconds, and a final speed of 4000 rpm is used for spinning for 30 seconds. After spin-coating the photoresist, the sample is placed on a hot plate and baked at 100°C for about 90 seconds to remove the solvent in the photoresist and achieve a solid film effect.

[0034] (2) Place the sample in a laser direct writing device, specifically, Microwriter ML3. Import the GDS format file with the micron-scale pattern design into the device and convert the data into a format file that can be read by the laser direct writing device. Then, use 30mJ / cm 2 After exposure, the sample was removed from the equipment and placed in an AZ series photoresist developer, specifically 3038 developer (a mixture of 2.38% tetramethylammonium hydroxide and water). After developing in the developer for 30 seconds, the sample was placed in deionized water to remove any remaining developer and achieve a fixing effect.

[0035] (3) The sample with the photolithographic pattern is placed in the coating equipment to grow the material layer, and 50nmTi+100nmAu is evaporated on the material by electron beam, and a layer of material layer is coated on the photolithographic sample.

[0036] (4) Place the sample in a 70°C water bath and heat acetone for 12 hours to remove the material on top of the photoresist. Only the material layer without photoresist remains in the exposed area, and the first part of the micron pattern is transferred to the material layer.

[0037] (5) The sample is then placed in a slurry coater and vacuumed. A PMMA / ZEP series electron beam photoresist, specifically PMMA A2 electron beam photoresist, is used. The electron beam photoresist is drawn into a dropper and dripped onto the sample. The slurry is slurried at an initial speed of 500 rpm for 5 seconds, followed by a final speed of 2000 rpm for 30 seconds. The sample is then baked on a hot plate at 180°C for approximately 90 seconds to remove the solvent from the electron beam photoresist and achieve a solid film.

[0038] (6) Place the sample into an electron beam lithography device, specifically a Raith EBL device. Import the GDS format file with the nanoscale pattern design into the device and convert the data into a format file that can be read by the electron beam lithography device. Then, after alignment using the overlay mark, use an acceleration voltage of 20keV and 220uC / cm 2 After exposure to a dose of 100 nm, the sample was taken out of the device and placed in a developer of PMMA series photoresist (a solution of tetramethyl dipentyl ketone and isopropyl alcohol in a ratio of 1:3) for 120 seconds. Then, the sample was placed in isopropyl alcohol to remove the residual developer to achieve a fixing effect and form a nanoscale pattern.

[0039] (7) The sample with the photolithographic pattern is placed in the coating equipment to grow the material layer, and 50nmTi+100nmAu is evaporated on the material by electron beam, and a layer of material layer is coated on the photolithographic sample.

[0040] (8) The sample was placed in a 70°C water bath heated with acetone for 12 hours to remove the material above the photoresist, as used in the present invention. Only the exposed area without the photoresist remained, and the second portion of the nanopattern was transferred to the material layer.

[0041] Example 2

[0042] A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask, compared with Example 1, changes the substrate material in step (1) to a silicon semiconductor, and ultimately achieves high-precision, high-efficiency, and low-cost manufacturing and transfer of micro-nano patterns by multiple photolithography without a mask.

[0043] Example 3

[0044] A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask. Compared with Example 1, the thin film growth method in step (3) is changed to a thin film growth method of magnetron sputtering, which can ultimately complete the high-precision, high-efficiency, and low-cost manufacturing and transfer of micro-nano patterns by multiple photolithography without a mask.

[0045] Example 4

[0046] A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask. Compared with Example 1, the photoresist structure in step (1) is changed from one layer of photoresist to two layers of photoresist, wherein the newly added layer of photoresist is thinner and more sensitive to increase the fault tolerance of stripping.

[0047] Example 5

[0048] A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask. Compared with Example 1, the number of electron beam photoresist layers in step (3) is changed from one layer of electron beam photoresist to another layer of electron beam photoresist, wherein the newly added layer of electron beam photoresist is thinner and has higher sensitivity, so as to increase the fault tolerance of stripping.

[0049] like Figure 3 As shown, it is a plan view of the micro-nano pattern obtained in Example 1, and Figure 2 In contrast, the pattern produced is the same as the design during photolithography. Figure 1 The pattern edges are clear and steep, and the line width is consistent with the pattern produced by photolithography, completely restoring the design layout.

[0050] like Figure 4 The cross-section of the micro-nano pattern shown here shows the material's very steep lines, without the inclination angles typically seen with etching methods. This method has a very positive effect on the propagation properties of surface acoustic wave resonators, such as Q and electromechanical coupling coefficient. It also significantly impacts the performance of MEMS and optical waveguide devices.

[0051] Therefore, according to the nanoscale fine pattern processing method of the present invention, laser direct writing exposure and electron beam exposure are performed for patterns above 1 micron and patterns below 1 micron respectively, which can quickly and cost-effectively process nanoscale fine patterns, and the stripping method is used to transfer the photolithography pattern to the material layer, which can avoid the line width loss caused by etching and can perform pattern transfer more accurately.

Claims

1. A method for manufacturing and transferring micro-nano patterns by multiple photolithography without a mask, characterized in that: The following steps are involved: (1) using an organic solvent to clean the substrate material, spin-coating a photoresist on the substrate surface, and baking; (2) introducing a pattern into a laser direct writing device and performing laser direct writing exposure on a substrate material to obtain a pattern larger than 1 micron; Developing with a developer to remove the exposed photoresist and obtain a developed substrate material; (3) using a thin film growth method selected from electron beam evaporation, magnetron sputtering, or atomic layer deposition to coat the developed substrate material to obtain a coated substrate material; (4) Soaking the coated substrate material in a water bath of etching solution to heat it, separating the substrate material from the film layer, and peeling and transferring the photolithographic pattern to the film layer to obtain a pattern above the micron level; (5) spin coating a photoresist on the surface of the substrate material separated in step (4) and baking; (6) introducing a pattern into an electron beam exposure device, and performing electron beam exposure on the substrate material while aligning the overlay mark to obtain a pattern with a line width of less than 1 micron; Developing with a developer to remove the exposed photoresist and obtain a substrate material after secondary development; (7) using a thin film growth method selected from electron beam evaporation, magnetron sputtering, or atomic layer deposition to coat the substrate material after secondary development to obtain a substrate material after secondary coating; (8) The substrate material after secondary coating is immersed in a corrosive solution and heated in a water bath to separate the substrate material and the film layer, and the photolithographic pattern is peeled off and transferred to the film layer to obtain a nanoscale pattern.

2. The method according to claim 1, characterized in that In step (1), the organic solvent cleaning is to place the product in acetone and isopropyl alcohol for ultrasonic cleaning for 5 to 10 minutes in sequence, the photoresist is a photosensitive photoresist, and the substrate material is a silicon semiconductor or silicon oxide with a conductive film, or a sapphire insulator.

3. The method according to claim 1, characterized in that In step (2), the developer dosage is 10-100 mJ / cm 2 ; The developer is a photosensitive photoresist developer, and the developing time is 25 to 45 seconds.

4. The method according to claim 1, wherein In step (3), the coating film is made of a material selected from the group consisting of metal, semiconductor, and insulator.

5. The method according to claim 1, wherein In step (5), the photoresist is electron beam photoresist.

6. The method according to claim 1, characterized in that In step (6), the developer dosage is 100-500uC / cm 2 ; The developer is an electron beam photoresist developer, and the developing time is 90 to 150 seconds.

7. The method according to claim 1, characterized in that In step (1) or (5), the spin coating is specifically performed by using an initial rotation speed of 500-700 rpm for 5-10 seconds and a subsequent rotation speed of 1000-5000 rpm for 30-40 seconds; the baking temperature is 160-180°C and the time is 70-120 seconds.

8. The method according to claim 1, characterized in that In step (4) or (8), the etching solution is one of acetone or N-methylpyrrolidone solution, and the water bath heating temperature is 50-70° C. and the time is 2-24 hours.

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