Methods that facilitate electron beam negative adhesive stripping
By employing a dual-layer photoresist scheme and dry etching technology, the problems of low exposure efficiency and long development time of negative photoresist in electron beam lithography were solved, achieving efficient negative photoresist stripping and high-quality pattern formation.
Patent Information
- Application Number
- CN202610223624.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-25
- Publication Date
- 2026-05-26
AI Technical Summary
In electron beam lithography, when using negative photoresist, existing technologies suffer from low exposure efficiency and prolonged development time, leading to over-development of the pattern and making it impossible to form high-quality large-area patterns.
A dual-layer photoresist solution is adopted, including an etch-resistant electron beam negative resist layer and a sacrificial resist layer. The undercut structure is formed by electron beam exposure and dry etching to ensure that the negative resist is successfully peeled off during the lift-off process.
It improves the efficiency and pattern quality of electron beam lithography, avoids the problem of over-development of patterns caused by prolonged development time, and realizes the manufacturing of high-quality large-area patterns.
Smart Images
Figure CN122085622A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor manufacturing technology, and particularly relates to a method for electron beam stripping of negative adhesive. Background Technology
[0002] In research fields such as materials science, microelectronics, and optical imaging, fabricating high-quality electrodes or light-blocking layers is a crucial prerequisite for accurately reflecting the performance of materials or devices. Lift-off processes in photolithography are the fundamental method for realizing these structures. The lift-off process involves obtaining a patterned photoresist structure or metal mask on a substrate using photolithography, followed by depositing a target coating onto the mask using deposition techniques, and finally dissolving the photoresist with a resist remover or mechanically removing the metal hard mask to obtain the target patterned structure.
[0003] In lift-off processes, the success of the lift-off process is directly influenced by whether the sidewalls of the photoresist or metal mask can form an undercut structure where the bottom is wider than the top. For electron beam lithography, positive photoresists (such as PMMA) are more likely to form undercut structures than negative photoresists due to the scattering effect of electrons within the photoresist. Therefore, positive photoresists are typically used in electron beam lithography to form high-quality, high-precision patterns using lift-off processes. However, this method has a significant problem: when the area of positive photoresist to be lithographicated is large, the low exposure efficiency of electron beam lithography leads to longer exposure times, resulting in extremely low efficiency.
[0004] One solution is to use a two-layer photoresist scheme with an electron beam negative resist and a release resist, formulated with an alkaline developer. In this case, a longer development time is required to dissolve the release resist and form the undercut structure. This leads to overdevelopment of the photoresist pattern, failing to achieve the required high-quality pattern. Therefore, finding a method that enables a reliable lift-off process using negative photoresist is crucial for fabricating high-quality, large-area electrodes or photoblocking layers. This will improve the efficiency and pattern quality of electron beam lithography, meeting the manufacturing needs of high area ratio patterns. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for electron beam negative adhesive stripping.
[0006] Firstly, a method for electron beam negative adhesive stripping is provided, including: S1, Provide a substrate; S2. A sacrificial adhesive layer is formed on the substrate; S3. An etch-resistant electron beam negative adhesive layer is formed on the sacrificial adhesive layer; S4. Electron beam exposure is performed on the electron beam negative adhesive layer to form the target pattern; S5. Develop the electron beam negative photoresist layer after exposure; S6. Dry etching is performed on the sacrificial adhesive layer to form an undercut structure; S7. Deposit the target coating on the substrate; S8. Remove the sacrificial adhesive layer and the target coating and electron beam negative adhesive layer covering it to complete the peeling.
[0007] Preferably, after S2 and / or S3, the substrate after the adhesive layer is coated is baked.
[0008] Preferably, S1 further includes: cleaning the substrate with a solvent to remove organic contaminants from the surface.
[0009] Preferably, in the baking steps after S2 and / or S3, a hot plate or oven is used for baking for 1-45 minutes at a baking temperature of 65-210°C.
[0010] Preferably, in S4, the voltage used for electron beam exposure is 5-125 kV, and the dose value is 500-9000 μC / cm. 2 .
[0011] Preferably, in S6, the sacrificial adhesive layer is etched using oxygen via a plasma etching machine at an etching pressure of 10-100 mTorr and an oxygen flow rate of 20-80 sccm.
[0012] Preferably, in S8, the sacrificial adhesive layer is dissolved by a desmearing solution; the desmearing solution is selected from acetone, NMP, NEP, DMSO or alkaline desmearing solution.
[0013] Preferably, in S2, the sacrificial adhesive layer is a single-layer or multi-layer stacked structure.
[0014] Preferably, in S2 and / or S3, a spin coater is used to apply the adhesive layer at a speed of 3000-6000 rpm.
[0015] In a second aspect, a micro / nano structure prepared by any of the methods described in the first aspect is provided.
[0016] The beneficial effects of this invention are as follows: This invention uses a dual-layer scheme, with an upper layer being an etch-resistant electron beam negative resist layer and a lower layer being a sacrificial resist layer. By using electron beam photolithography to develop a smaller area of electron beam negative resist, and then placing it in plasma etching, the sacrificial resist layer is dry-etched to obtain the undercut structure. This reduces the area requiring photolithography and allows the negative resist to form an ideal undercut structure during electron beam exposure, ensuring smooth removal of the negative photoresist during the lift-off process. Compared to using electron beam negative resist with alkaline developer in conjunction with a release agent, this avoids over-development of the pattern due to prolonged development time, thus preventing issues with pattern quality. Attached Figure Description
[0017] Figure 1 A schematic diagram of the exposure area provided by the present invention; Figure 2 This is another schematic diagram of the exposure area provided by the present invention; Figure 3 This is a schematic diagram of the undercut structure formed using a single layer of photoresist provided by the present invention; Figure 4 This is a schematic diagram of the undercut structure formed using double-layer photoresist provided by the present invention; Figure 5 A process flow diagram of the electron beam negative adhesive stripping method provided by the present invention; Figure labeling: 1. Substrate; 2. Silicon wafer; 3. S1805 photoresist; 4. XR 1541-4 photoresist; 5. Photolithography area; 6. Metal deposition layer. Detailed Implementation
[0018] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
[0019] Example 1: To address the problems in the prior art, Embodiment 1 of this application provides a method for electron beam negative photoresist lift-off, which successfully solves the problem of failure to successfully lift-off when using negative photoresist to prepare high-quality electrodes or light-blocking layers.
[0020] Specifically, the electron beam negative resist lift-off method provided in this application is based on a specific dual-layer photoresist architecture combined with dry etching technology. Specifically, isotropic pretreatment of the sacrificial layer is performed using dry etching, and the synergistic effect of etching parameters and resist layer tolerance is utilized to achieve an undercut structure, thereby endowing the negative resist with efficient and clean lift-off characteristics. The dual-layer photoresist architecture, from bottom to top, includes: a sacrificial resist layer coated on the substrate, and an etch-resistant electron beam negative resist layer coated on top of the sacrificial resist layer. During the process, the top electron beam negative resist is first patterned (including exposure and development). This step only involves this resist layer, thus minimizing the exposure area. Subsequently, using the developed negative resist pattern as a mask, the lower sacrificial resist layer is dry etched, thereby forming a controllable undercut structure beneath the negative resist pattern. This undercut structure is crucial for the success of the subsequent lift-off process, effectively ensuring that the photoresist and the materials covering it can be cleanly and thoroughly removed after the functional layer is deposited.
[0021] For example, the method provided in Embodiment 1 of this application specifically includes: S1, Provide a substrate.
[0022] S2. A sacrificial adhesive layer is formed on the substrate.
[0023] S3. An etch-resistant electron beam negative adhesive layer is formed on the sacrificial adhesive layer.
[0024] Figure 1 This shows the area of the region that needs to be exposed when using positive or negative adhesives to prepare the light-blocking layer of an optical device. Figure 2 The diagram illustrates the fabrication of electrode devices using either positive or negative photoresist, and the required exposure area for each. It is evident that, to improve exposure efficiency and reduce exposure time in these devices, negative photoresist should be used.
[0025] S4. Electron beam exposure is performed on the electron beam negative adhesive layer to form the target pattern.
[0026] S5. Develop the electron beam negative photoresist layer after exposure.
[0027] S6. Dry etching is performed on the sacrificial adhesive layer to form an undercut structure.
[0028] S7. Deposit the target coating on the substrate.
[0029] S8. Remove the sacrificial adhesive layer and the target coating and electron beam negative adhesive layer covering it to complete the peeling.
[0030] Example 2: Based on Example 1, Example 2 of this application provides a more specific method for electron beam negative adhesive stripping, including: S1, Provide a substrate.
[0031] S1 also includes: cleaning the substrate with a solvent to remove organic contaminants from the surface. Furthermore, a plasma cleaner can be used to further remove surface residues and increase adhesion.
[0032] S2. A sacrificial adhesive layer is formed on the substrate, and the substrate after the adhesive layer is coated is baked.
[0033] In S2, the sacrificial resist layer is a single-layer or multi-layer stacked structure (prepared by sequentially spin-coating multiple sacrificial resist layers and then stacking them). Furthermore, the sacrificial resist layer material can be PMMA series, ZEP 520A, AR-BR 5400 photoresist, LOR series, S1800 series, or other ultraviolet, deep ultraviolet, or extreme ultraviolet photoresists without etching resistance and insensitive to electron beams.
[0034] S3. Form an etch-resistant electron beam negative adhesive layer on the sacrificial adhesive layer, and bake the substrate after coating the adhesive layer.
[0035] In the baking steps following S2 and S3, use a hot plate or oven to bake for 1-45 minutes at a temperature of 65-210℃.
[0036] In S2 and S3, a spin coater is used to apply the adhesive layer at a speed of 3000-6000 rpm.
[0037] In addition, electron beam negative adhesives include DOW's XR 1541 series and FOX series, Allrsist's SX AR-N 8200 series and AR-N 7520, AQ materials' H-SiOx series, Shipley's SAL 601, or other etching-resistant electron beam negative adhesives.
[0038] S4. Electron beam exposure is performed on the electron beam negative adhesive layer to form the target pattern.
[0039] In S4, the voltage used for electron beam exposure is 5-125 kV, and the dose value is 500-9000 μC / cm. 2 .
[0040] S5. Develop the electron beam negative photoresist layer after exposure.
[0041] For example, the electron beam negative photoresist is developed using a preset developer solution for 10 seconds to 5 minutes, and then rinsed with deionized water.
[0042] S6. Dry etching is performed on the sacrificial adhesive layer to form an undercut structure (e.g.) Figure 3 and Figure 4 (As shown).
[0043] In S6, the sacrificial adhesive layer is etched using oxygen via a plasma etching machine at an etching pressure of 10-100 mTorr and an oxygen flow rate of 20-80 sccm.
[0044] S7. Deposit the target coating on the substrate.
[0045] S8. Remove the sacrificial adhesive layer and the target coating and electron beam negative adhesive layer covering it to complete the peeling.
[0046] In S8, the sacrificial adhesive layer is dissolved by a desmearing solution; the desmearing solution is selected from acetone, NMP (1-methyl-2-pyrrolidone), NEP (nitroethylpyrrolidone), DMSO (dimethyl sulfoxide), or an alkaline desmearing solution.
[0047] Furthermore, the above-mentioned approach can also be applied to lift-off processes in UV exposure and laser direct writing. In UV exposure and laser direct writing, the top of the photoresist absorbs the most energy, while the bottom absorbs the least, making it easier for negative photoresist to form a bottom-cutting effect. When it is necessary to enhance the bottom-cutting effect and improve the success rate of lift-off, a combination of appropriate etch-resistant negative photoresist and sacrificial photoresist layers can be used.
[0048] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.
[0049] Example 3: Based on Example 2, Example 3 of this application provides a more specific method for electron beam negative adhesive stripping, such as... Figure 3 As shown, it includes: S1. Using a silicon wafer as a substrate, the substrate is cleaned with acetone and isopropanol to remove organic contaminants from the surface. The surface residue is further removed by a plasma cleaner to increase adhesion.
[0050] S2. Spin-coating sacrificial resist layer: Using a spin coater, spin-coat the S1805 sacrificial photoresist layer onto the silicon wafer surface at a speed of 3000-6000 rpm for 50 seconds, resulting in a thickness of 500 nm.
[0051] S3. Place the substrate on a hot plate and bake to remove residual solvent from the release adhesive and increase the adhesion between the release adhesive and the substrate. The baking temperature is 100-160℃, and the time is 2 minutes.
[0052] S4. Spin-coating electron beam negative resist: Using a spin coater, spin-coat XR 1541-4 photoresist onto the surface of the sacrificial layer at a speed of 3000-6000 rpm for 30 seconds, with a thickness of 100 nm.
[0053] S5. Place the substrate on a hot plate and bake at 150°C for 1 minute. S6, Electron Beam Lithography: Electron beam photoresist reads the exposure file and exposes the image using a dose of 500-4000 uc / cm²; S7. Development: After exposure, immerse the substrate in MF319 developer for 30 seconds, then immerse it in deionized water for 1 minute to remove surface solvent, and blow dry any remaining water. S8. Observe and characterize the pattern formed in the XR 1541-4 photoresist to ensure there are no quality issues; S9. Oxygen Plasma Etching: Place the substrate in an oxygen plasma cleaning and etching machine and etch for 3 minutes at a pressure of 20 mTorr and a gas flow rate of 50 sccm. S10, Metal Deposition: The substrate is placed in an electron beam evaporation coating system to deposit chromium and gold. Chromium is used as an adhesive layer to prevent the gold pattern from falling off. The total thickness of the deposited metal is 200nm. S11, lift-off: After deposition, the substrate is placed in acetone to complete the lift-off, and then placed in isopropanol to clean the device surface, thus completing the device fabrication. It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 2 can be referred to each other, and will not be repeated in this application.
Claims
1. A method for electron beam negative adhesive stripping, characterized in that, include: S1, Provide a substrate; S2. A sacrificial adhesive layer is formed on the substrate; S3. An etch-resistant electron beam negative adhesive layer is formed on the sacrificial adhesive layer; S4. Electron beam exposure is performed on the electron beam negative adhesive layer to form the target pattern; S5. Develop the electron beam negative photoresist layer after exposure; S6. Dry etching is performed on the sacrificial adhesive layer to form an undercut structure; S7. Deposit the target coating on the substrate; S8. Remove the sacrificial adhesive layer and the target coating and electron beam negative adhesive layer covering it to complete the peeling.
2. The electron beam negative adhesive stripping method according to claim 1, characterized in that, Following S2 and / or S3, the substrate after the adhesive layer has been coated is baked.
3. The electron beam negative adhesive stripping method according to claim 2, characterized in that, S1 also includes: cleaning the substrate with a solvent to remove organic contaminants from the surface.
4. The electron beam negative adhesive stripping method according to claim 3, characterized in that, In the baking steps following S2 and / or S3, bake on a hot plate or in an oven for 1-45 minutes at a temperature of 65-210℃.
5. The electron beam negative adhesive stripping method according to claim 4, characterized in that, In S4, the voltage used for electron beam exposure is 5-125 kV, and the dose value is 500-9000 μC / cm. 2 .
6. The electron beam negative adhesive stripping method according to claim 5, characterized in that, In S6, the sacrificial adhesive layer is etched using oxygen via a plasma etching machine at an etching pressure of 10-100 mTorr and an oxygen flow rate of 20-80 sccm.
7. The electron beam negative adhesive stripping method according to claim 6, characterized in that, In S8, the sacrificial adhesive layer is dissolved by a desmearing solution; the desmearing solution is selected from acetone, NMP, NEP, DMSO or alkaline desmearing solution.
8. The electron beam negative adhesive stripping method according to claim 7, characterized in that, In S2, the sacrificial adhesive layer is a single-layer or multi-layer stacked structure.
9. The electron beam negative adhesive stripping method according to claim 8, characterized in that, In S2 and / or S3, a spin coater is used to apply the adhesive layer at a speed of 3000-6000 rpm.
10. A micro / nano structure prepared by the method according to any one of claims 1 to 9.