Rework cleaning method for photolithographic structure on substrate

Abstract

The present disclosure provides a rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure comprises, from bottom to top, a substrate, an organic bottom structure layer, a silicon-based hard mask intermediate structure layer, and a photoresist layer. The method comprises: S1, removing the photoresist layer by dry etching or wet cleaning; S2, removing the silicon-based hard mask intermediate structure layer by reactive ion etching; S3, removing the organic bottom structure layer by inductively coupled plasma etching; S4, performing oblique etching on the residual particles on the surface of the substrate by reactive ion etching to reduce the contact area between the residual particles and the substrate; S5, sequentially immersing the substrate obtained in S4 in an organic solvent and then rinsing in deionized water; S6, immersing the substrate obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles after the oblique etching; and then rinsing with deionized water to complete the rework cleaning. The method disclosed herein can effectively remove residual particles and enable the substrate to meet the standards for reuse.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor manufacturing, and in particular to a rework cleaning method for a photolithography structure on a substrate. Background Art

[0002] Thanks to advances in photolithography equipment, materials, and processes, the size of devices on chips is shrinking. To ensure parameter requirements such as feature line width and aspect ratio, multiple layers of photolithography material are stacked on the substrate, and etching is performed after the photolithography process. Integrated circuit chip process units are complex, requiring multiple photolithography and etching processes to achieve the designed pattern. If the photoresist pattern on the substrate does not meet the requirements after the photolithography process, rework and cleaning will result in wasted process materials and reduced chip production capacity.

[0003] To improve the etching requirements of feature lines, new photoresist materials are constantly being used. Three-layer photoresist materials are generally used for etching transfer. These three-layer photoresist materials typically include an organic base structure layer, a silicon-based hard mask intermediate structure layer, and a photoresist layer. Through rework and cleaning processes, the substrate can be reused.

[0004] The existing rework cleaning process includes the following steps: 1. Using O2 plasma gas to etch and remove the photoresist layer on the surface of the substrate; 2. Using CF4 plasma gas to etch and remove the Si-containing anti-reflective coating on the substrate (equivalent to the silicon-based hard mask intermediate structure layer); 3. Using O2 plasma gas to etch and remove the spin-coated organic carbon layer on the substrate (equivalent to the organic bottom structure layer).

[0005] Among them, the spin-coated organic carbon layer needs to be baked at 240°C or higher temperature after spin coating, and the spin-coated organic carbon layer is easily carbonized after being etched by O2 plasma gas, leaving some difficult-to-remove particles on the surface of the substrate, which affects the reuse of the substrate.

[0006] Therefore, it is necessary to develop a rework cleaning technology that can remove the particles cleanly without damaging the device structure. Summary of the Invention

[0007] (1) Technical issues to be resolved

[0008] In response to the above problems, the present disclosure provides a rework cleaning method for a photolithographic structure on a substrate, which is used to solve technical problems such as traditional methods being difficult to remove residual particles after carbonization of the organic underlying structure layer or cleaning easily damaging the device structure.

[0009] (2) Technical solution

[0010] On the one hand, the present disclosure provides a rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure includes, from bottom to top, a substrate, an organic bottom structure layer, a silicon-based hard mask intermediate structure layer, and a photoresist layer, and comprises: S1, removing the photoresist layer by dry etching or wet cleaning; S2, removing the silicon-based hard mask intermediate structure layer by reactive ion etching; S3, removing the organic bottom structure layer by inductively coupled plasma etching; S4, performing oblique etching on residual particles on the surface of the substrate by reactive ion etching to reduce the contact area between the residual particles and the substrate, thereby obtaining residual particles after oblique etching; S5, sequentially immersing the substrate obtained in S4 in an organic solvent and washing in deionized water; S6, immersing the substrate obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove residual particles after oblique etching; and then washing with deionized water to complete the rework cleaning process.

[0011] Furthermore, the solvent used for wet cleaning in S1 includes one or more of acetone and N-methylpyrrolidone.

[0012] Furthermore, the material of the silicon-based hard mask intermediate structure layer in S2 includes an anti-reflective coating containing Si; the etching gas used in the reactive ion etching in S2 is CHF3, the etching gas flow rate is 20~100sccm, the etching chamber pressure is 0.1~10Pa, and the etching power is 40~100W.

[0013] Furthermore, the material of the organic bottom structural layer in S3 includes spin-coated organic carbon; the etching gas used in the inductively coupled plasma etching in S3 includes at least O2, the etching gas flow rate is 30~100sccm, the etching chamber pressure is 0.1~10Pa, the etching power supply power is 50~150W, the etching RF power is 10~50W, and the etching temperature is 8~10℃.

[0014] Furthermore, S4 includes: rotating the substrate so that the reactive ion source is tilted relative to the substrate surface, and performing tilted etching on the residual particles on the substrate surface by reactive ion etching; wherein the tilted angle is 15 to 75 degrees.

[0015] Furthermore, S4 includes: etching the longitudinal cross section or the lower portion of the longitudinal cross section of the residual particles on the surface of the substrate into an inverted trapezoidal shape by using reactive ion etching.

[0016] Furthermore, the etching gas used in the reactive ion etching in S4 is O2, the flow rate of the etching gas is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W.

[0017] Furthermore, the immersion time in the organic solvent in S5 is 5 to 10 minutes, and the organic solvent includes one or more of ethanol, acetone and N-methylpyrrolidone; the temperature of the heated concentrated sulfuric acid and hydrogen peroxide mixed solution in S6 is 100 to 150° C., the molar ratio of concentrated sulfuric acid to hydrogen peroxide is 3:1 to 10:1, and the immersion time is 30 to 60 minutes; S5 and S6 adopt a single-wafer cleaning method.

[0018] On the other hand, the present disclosure provides a rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure includes, from bottom to top, a substrate, an organic bottom structure layer, and a silicon-based hard mask intermediate structure layer, and the method includes: S2, removing the silicon-based hard mask intermediate structure layer by reactive ion etching; S3, removing the organic bottom structure layer by inductively coupled plasma etching; S4, performing oblique etching on residual particles on the surface of the substrate by reactive ion etching to reduce the contact area between the residual particles and the substrate, thereby obtaining residual particles after oblique etching; S5, sequentially immersing the substrate obtained by S4 in an organic solvent and washing it in deionized water; S6, immersing the substrate obtained by S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove residual particles after oblique etching; and then washing with deionized water to complete the rework cleaning process.

[0019] Another aspect of the present disclosure provides a rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure includes a substrate and an organic underlying structure layer from bottom to top, and comprises: S3, removing the organic underlying structure layer by using inductively coupled plasma etching; S4, performing oblique etching on residual particles on the surface of the substrate by using reactive ion etching to reduce the contact area between the residual particles and the substrate, thereby obtaining residual particles after oblique etching; S5, sequentially immersing the substrate obtained in S4 in an organic solvent and washing it in deionized water; S6, immersing the substrate obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove residual particles after oblique etching; and then washing with deionized water to complete the rework cleaning process.

[0020] (3) Beneficial effects

[0021] The disclosed rework cleaning method for photolithographic structures on substrates utilizes reactive ion etching to perform oblique etching on the residual particles on the substrate surface to reduce the contact area between the residual particles and the substrate, which facilitates the effective removal of the residual particles during subsequent immersion in a mixed solution of concentrated sulfuric acid and hydrogen peroxide. Furthermore, each processing step does not adversely affect the structure on the substrate, and the substrate that has completed the rework cleaning can meet the standards for reuse, reducing the impact of the rework process on the substrate. The rework cleaning method has good etching uniformity and low contamination, which can reduce defects introduced by the rework process. Furthermore, the method is applicable not only to situations where rework is performed after all three layers of photolithographic materials are prepared, but also to situations where rework is performed after one or two layers of the three layers of photolithographic materials are prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A flow chart schematically illustrates a method for rework cleaning of a photolithographic structure on a substrate according to an embodiment of the present disclosure;

[0023] Figure 2 Schematically shows a schematic diagram of the cross-sectional changes of a three-layer photolithography structure in a rework cleaning process according to an embodiment of the present disclosure;

[0024] Figure 3 Schematically shows a schematic diagram of the cross-sectional changes of a two-layer photolithography structure in a rework cleaning process according to an embodiment of the present disclosure;

[0025] Figure 4 A schematic diagram showing the cross-sectional changes of a layer of photolithographic structure in a rework cleaning process according to an embodiment of the present disclosure is shown;

[0026] Figure 5 Schematically showing a cross-sectional topography and a surface topography in Example 1 of the present disclosure and a surface topography in Comparative Example 1;

[0027] Description of reference numerals:

[0028] 11, wafer; 12, base; 2, substrate; 3, organic underlying structure layer; 4, silicon-based hard mask intermediate structure layer; 5, photoresist layer; 6, residual particles; 7, residual particles after oblique etching; 8, part of the organic underlying structure layer. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] The present disclosure provides a rework cleaning method for a photolithographic structure on a substrate. The reworked photolithographic structure includes, from bottom to top, a substrate 2, an organic bottom structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5. Figure 1 The method includes: S1, removing the photoresist layer 5 by dry etching or wet cleaning; S2, removing the silicon-based hard mask intermediate structure layer 4 by reactive ion etching (RIE); S3, removing the organic bottom structure layer 3 by inductively coupled plasma (ICP) etching; S4, performing oblique etching on the residual particles 6 on the surface of the substrate 2 by reactive ion etching (RIE) to reduce the contact area between the residual particles 6 and the substrate 2, thereby obtaining residual particles 7 after oblique etching; S5, sequentially immersing the substrate 2 obtained by S4 in an organic solvent and then washing it in deionized water; S6, immersing the substrate 2 obtained by S5 in a mixed solution of heated concentrated sulfuric acid and hydrogen peroxide to remove the residual particles 7 after oblique etching; and then washing it with deionized water to complete the rework cleaning process.

[0032] The method disclosed in the present invention is widely applicable to various substrate materials. The materials of the substrate 2 include Si, SiO2, and polysilicon gate, etc. Figure 2 The cross-sectional view of the photolithography structure in the first rework cleaning process is schematically shown. Figure 2 As shown in Figure 2A, three layers of photoresist materials are prepared on the substrate 2, including an organic underlying structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5. Each film layer is inspected, and if there is a problem, rework cleaning is required. Rework cleaning requires the removal of all three layers of photoresist materials and the organic underlying structure layer that is carbonized after high-temperature baking and ICP etching. The carbonized organic underlying structure layer remains on the surface of the substrate 2 and is difficult to remove. The present invention utilizes RIE to perform oblique etching on the residual particles 6 on the surface of the substrate to reduce the contact area between the residual particles 6 and the substrate 2, thereby obtaining residual particles 7 after oblique etching; and then uses a mixed solution of concentrated sulfuric acid and hydrogen peroxide to effectively remove the residual particles 7 after oblique etching, and each processing step will not adversely affect the structure on the substrate. The substrate 2 that has completed rework cleaning can meet the standard for reuse, reducing the impact of the rework process on the substrate.

[0033] Based on the above embodiment, the solvent used for wet cleaning in S1 includes one or more of acetone and N-methylpyrrolidone.

[0034] Rework cleaning first requires removing the top photoresist layer 5. Preferably, wet cleaning is used to remove the photoresist layer 5. Wet cleaning has a faster removal rate than dry etching, and dry etching may also introduce new impurities during the transfer in the equipment. Wet cleaning uses an organic solvent to remove the photoresist. The specific type of organic solvent is selected based on the material of the photoresist layer 5. It is sufficient to ensure that the organic solvent can dissolve the photoresist layer 5 but does not react with the film layers below the photoresist layer 5. Commonly used solvents include acetone, N-methylpyrrolidone (NMP), etc. In S1, an organic solvent is used to dissolve the photoresist layer 5. After cleaning with the organic solvent, the photoresist layer 5 is removed, and the resulting structure is as shown. Figure 2 As shown in Figure 2B.

[0035] Based on the above embodiment, the material of the silicon-based hard mask intermediate structure layer 4 in S2 includes a Si-containing anti-reflection coating (Si bottom anti-reflection coating, SiBARC); the etching gas used in the reactive ion etching in S2 is CHF3, the etching gas flow rate is 20~100sccm, the etching chamber pressure is 0.1~10Pa, and the etching power is 40~100W.

[0036] Next, the silicon-based hard mask intermediate structure layer 4 under the photoresist layer 5 is removed. The silicon-based hard mask intermediate structure layer 4 is usually made of SiBARC, and SiBARC is removed by RIE. The etching gas is CHF3. CHF3 can provide carbon nuclei and fluorine radicals. Fluorine radicals react chemically with Si in SiBARC to generate volatile gases, thereby removing SiBARC. CHF3 has a better selectivity, a stable etching speed, and is easy to adjust the etching time. The flow rate and chamber pressure of the etching gas within the above range are conducive to regulating the uniformity of SiBARC, and are easy to adjust the etching rate and time, making SiBARC removal cleaner. After using RIE to remove the silicon-based hard mask intermediate structure layer 4 in S2, the resulting structure is as follows Figure 2 As shown in 2C.

[0037] Based on the above embodiment, the material of the organic underlying structural layer 3 in S3 includes spin-coated organic carbon (Spinon Carbon, SOC); the etching gas used in the inductively coupled plasma etching in S3 includes at least O2, the etching gas flow rate is 30~100sccm, the etching chamber pressure is 0.1~10Pa, the etching power is 50~150W, the etching RF power is 10~50W, and the etching temperature is 8~10℃.

[0038] Next, the organic bottom structure layer 3 under the silicon-based hard mask intermediate structure layer 4 is removed. The organic bottom structure layer 3 is usually made of SOC material, and the SOC material is removed by ICP etching. The etching gas includes at least O2, which can be pure O2 or O2+H2. The etching RF power within the above range is conducive to adjusting the etching rate. The etching temperature within the above range is to control the temperature of the substrate 2 surface during the etching process and reduce the impact on the etching efficiency. After using ICP etching to remove the organic bottom structure layer 3 in S3, the resulting structure is as follows Figure 2 As shown in Figure 2D, carbonization of the SOC material is likely to occur after ICP etching, leaving residual particles 6 on the surface of the substrate 2. Residual particles 6 may also be generated during the preparation of the organic underlying structural layer 3. To meet the standards for substrate reuse, these residual particles 6 must be further removed.

[0039] Based on the above embodiment, S4 includes: rotating the substrate 2 so that the reactive ion source is tilted relative to the surface of the substrate 2, and using reactive ion etching to obliquely etch the residual particles 6 on the surface of the substrate 2; wherein the tilt angle is 15 to 75°.

[0040] In the method disclosed herein, the second RIE adopts plasma inclined etching. By rotating the substrate 2 so that the substrate 2 is inclined relative to the reactive ion source after RF ignition in the device, the residual particles 6 on the surface will be etched obliquely. This inclined etching method can reduce the contact area between the residual particles 6 and the substrate 2, which is beneficial for subsequent removal by solution corrosion. Since the residual particles 6 are the products of carbonization of the SOC material after high-temperature baking and ICP etching, it is impossible to remove all the residual particles 6 directly by etching. Therefore, the present disclosure adopts the method of first oblique etching and then using solution removal, which can completely remove the residual particles 6. Preferably, the angle of the inclined setting is 45°. The 45° inclination angle is beneficial to reducing the contact area between the residual particles and the substrate, making it easier to remove the residual particles 6 in contact with the substrate 2.

[0041] On the basis of the above embodiment, S4 includes: etching the longitudinal cross section or the lower part of the longitudinal cross section of the residual particles 6 on the surface of the substrate 2 into an inverted trapezoidal shape by using reactive ion etching.

[0042] The cross section of the residual particle 6 is considered to be approximately square or rectangular. After RIE oblique etching, the structure of the residual particle 7 after oblique etching is as follows: Figure 2 If the tilt angle is larger, the upper part of the residual particle 6 is not removed, and only the small corner of the lower part of the residual particle 6 is removed, then the lower part of the longitudinal cross section will be an inverted trapezoid.

[0043] Based on the above embodiment, the etching gas used in the reactive ion etching in S4 is O2, the flow rate of the etching gas is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W.

[0044] Selecting O2 or O2+H2 as etching gas is beneficial to better remove the carbonized organic underlying structural layer 3; and setting the etching power within the above range is beneficial to adjusting the etching rate.

[0045] Based on the above embodiment, the immersion time in the organic solvent in S5 is 5 to 10 minutes, and the organic solvent includes one or more of ethanol, acetone and N-methylpyrrolidone; the temperature of the heated mixed solution of concentrated sulfuric acid and hydrogen peroxide in S6 is 100 to 150° C., the molar ratio of concentrated sulfuric acid to hydrogen peroxide is 3:1 to 10:1, and the immersion time is 30 to 60 minutes; both S5 and S6 adopt a single-wafer cleaning method.

[0046] In S5, the substrate 2 is immersed in an organic solvent, and then ultrasonically cleaned in deionized water in order to remove basic organic particles. In S6, the substrate 2 is immersed in a mixed solution of heated concentrated sulfuric acid and hydrogen peroxide. The mixed solution is highly corrosive and can effectively remove organic particles on the surface of the substrate 2 without changing the micro-roughness of the surface of the silicon-based substrate 2; and is bubble-cleaned 3 times with deionized water in order to remove the residual particles 7 after the above-mentioned oblique etching. The single-wafer cleaning method is to perform a separate cleaning operation on each substrate 2, and the steps include S5 and S6. Single-wafer cleaning makes it easy to control the cleaning quality and can also improve the cleaning uniformity of different positions of the single-wafer substrate. Compared with multi-wafer cleaning, single-wafer cleaning can reduce the additional introduction of impurities and improve the cleaning effect of the substrate. After the soaking and cleaning processes are completed, the obtained photolithographic structure is as follows Figure 2 As shown in 2F.

[0047] The uniformity of each etching step in the rework cleaning method disclosed herein is good, pollution is low, and defects introduced by the rework process can be reduced. The substrate after rework cleaning can meet the standards for reuse, reducing the impact of the rework process on the substrate.

[0048] The rework cleaning method disclosed herein is not only applicable to the situation where rework is performed after all three layers of photoresist materials are prepared, but also to the situation where rework is performed after one or two layers of photoresist materials among the three layers of photoresist materials are prepared. The latter situation will be described below.

[0049] The present disclosure also provides a rework cleaning method for a photolithographic structure on a substrate. The reworked photolithographic structure includes, from bottom to top, a substrate 2, an organic bottom structure layer 3, and a silicon-based hard mask intermediate structure layer 4. The rework cleaning method includes: S2, using reactive ion etching to remove the silicon-based hard mask intermediate structure layer 4; S3, using inductively coupled plasma etching to remove the organic bottom structure layer 3; S4, using reactive ion etching to perform oblique etching on the residual particles 6 on the surface of the substrate 2 to reduce the contact area between the residual particles 6 and the substrate 2, thereby obtaining residual particles 7 after oblique etching; S5, sequentially immersing the substrate 2 obtained in S4 in an organic solvent and cleaning it in deionized water; S6, immersing the substrate 2 obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles 7 after oblique etching; and finally, cleaning with deionized water to complete the rework cleaning process.

[0050] Figure 3 The cross-sectional view of the photolithography structure in the second rework cleaning process is schematically shown. Figure 3 As shown in Figure 3A, two layers of photoresist material are formed on substrate 2, including an organic bottom layer 3 and a silicon-based hard mask intermediate layer 4. This means that substrate 2 is only coated with two layers of photoresist material (no photoresist layer is applied yet). Each layer is inspected, and if any problems are found, rework and cleaning are required. In this case, the photoresist layer removal step is not required, and the process begins directly with the removal of the silicon-based hard mask intermediate layer 4. The specific steps S2 to S6 are the same as the first rework and cleaning process and are not repeated here.

[0051] The present disclosure also provides a rework cleaning method for a photolithographic structure on a substrate. The reworked photolithographic structure includes, from bottom to top, a substrate 2 and an organic underlying structure layer 3. The rework cleaning method includes: S3, using inductively coupled plasma etching to remove the organic underlying structure layer 3; S4, using reactive ion etching to perform oblique etching on the residual particles 6 on the surface of the substrate 2 to reduce the contact area between the residual particles 6 and the substrate 2, thereby obtaining residual particles 7 after oblique etching; S5, sequentially immersing the substrate 2 obtained in S4 in an organic solvent and cleaning it in deionized water; S6, immersing the substrate 2 obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles 7 after oblique etching; and then cleaning with deionized water to complete the rework cleaning process.

[0052] Figure 4 The cross-sectional view of the photolithography structure in the third rework cleaning process is schematically shown. Figure 4As shown in Figure 4A, a layer of photoresist material has been deposited on substrate 2. Specifically, substrate 2 is coated with only an organic underlying structural layer 3 (and not yet with a photoresist layer and a silicon-based hard mask intermediate structural layer). Each layer is inspected, and if any problems are found, rework and cleaning are required. In this case, the removal of the photoresist layer and the silicon-based hard mask intermediate structural layer is not necessary, and the process begins directly with the removal of the organic underlying structural layer 3. The specific steps S3 to S6 are the same as those in the first rework and cleaning process and are not further described here.

[0053] This disclosure provides three methods for cleaning reworked photolithographic structures on substrates, particularly for cleaning reworked photolithographic materials on three substrates. The disclosed methods effectively remove residual particles from the substrate surface, ensuring that the cleaned substrates meet reuse standards and minimizing the impact of rework on the substrate.

[0054] The present disclosure is further described below through specific embodiments. The rework cleaning method of the photolithographic structure on the substrate is specifically described in the following examples. However, the following examples are only used to illustrate the present disclosure and the scope of the present disclosure is not limited thereto.

[0055] The present invention discloses a rework cleaning method for a photolithographic structure on a substrate, comprising performing the following steps in sequence:

[0056] Step 1: The substrate 2 for the photolithography process includes a wafer 11 and / or a base 12. The base 12 comprises materials such as Si, SiO2, and a polysilicon gate. Three layers of photolithography material are spin-coated onto the substrate 2. These layers include an organic underlying structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5. The organic underlying structure layer 3 is typically a SOC material, and the silicon-based hard mask intermediate structure layer 4 is typically a SiBARC material. The thickness of the organic underlying structure layer 3 is 50 to 200 nm, the thickness of the silicon-based hard mask intermediate structure layer 4 is 10 to 50 nm, and the thickness of the photoresist layer 5 is 20 to 100 nm.

[0057] Step 2: After the spin coating process and photolithography process of each material layer are completed, the material layer and the photolithography pattern are inspected. If the process results are qualified, the subsequent process is carried out. If there are problems, the rework and cleaning process is carried out.

[0058] Step 3: If a rework cleaning process is performed, it includes the following sub-steps:

[0059] Step 31: wet cleaning is performed to remove the photoresist layer 5 using an organic solvent that does not react with the material layer below the photoresist layer 5. The organic solvent includes acetone, N-methylpyrrolidone (NMP), etc.; this is equivalent to the above step S1.

[0060] Step 32: Perform a first reactive ion etching (RIE) to remove the silicon-based hard mask intermediate structure layer 4. The etching gas used in this first RIE is CHF3; wherein the CHF3 gas flow rate is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W; this is equivalent to the above-mentioned step S2.

[0061] Step 33: Perform ICP etching to remove most of the organic underlying structural layer 3, leaving some carbonized particles 6 that are difficult to remove. The ICP etching gas used is O2; the O2 gas flow rate is 30-100 sccm, the etching chamber pressure is 0.1-10 Pa, the ICP power is 50-150 W, the etching RF power is 10-50 W, and the etching temperature is 8-10°C. This is equivalent to step S3 above.

[0062] Step 34: Perform a second reactive ion etching (RIE) to reduce the contact area between the residual particles 6 and the substrate 2, obtaining the residual particles 7 after the oblique etching. The etching gas for this second plasma etching is O2, the etching oblique angle is 15-75°, the optimal etching angle is 45°, the O2 gas flow rate is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W; this is equivalent to the above-mentioned step S4.

[0063] Step 35: Soak the substrate 2 obtained in step 34 in an organic solvent for 5-10 minutes, then ultrasonically clean it in deionized water. The purpose of using the organic solvent is to remove basic organic particles. The organic solvent includes ethanol, acetone, and N-methylpyrrolidone (NMP). This is equivalent to step S5 above.

[0064] Step 36: Soak the substrate 2 obtained in step 35 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide for 30 to 60 minutes, and then clean it three times by bubbling in deionized water. The purpose of soaking in the mixed solution is to remove the residual particles 7 after the oblique etching. The ratio of the mixed solution is 3:1 to 10:1, and the temperature is 100 to 150°C. At this point, the rework cleaning process is completed, which is equivalent to the above-mentioned step S6.

[0065] In addition, this embodiment is not only applicable to the situation where rework is performed after all three layers of photoresist materials are prepared, but also applicable to the situation where rework is performed after one or two layers of photoresist materials among the three layers of photoresist materials are prepared, which will not be described in detail here.

[0066] According to the above steps 1 to 3, three specific examples and one comparative example are provided below.

[0067] In the following embodiments, the first situation corresponds to the case where a problem occurs after the spin coating process of the photoresist layer 5 is completed or after the photolithography process is completed. Figure 2 Shown, including Figure 2 A~ Figure 2 F; After the spin coating process is completed, the silicon-based hard mask intermediate structure layer 4 is inspected and a problem occurs, corresponding to the second situation, such as Figure 3 Shown, including Figure 3 A~ Figure 3 F; The organic bottom structure layer 3 spin coating process is completed when the inspection has problems corresponding to the third situation, such as Figure 4 Shown, including Figure 4 A~ Figure 4 F.

[0068] Example 1:

[0069] The rework cleaning method of the photolithographic structure on the substrate in this embodiment includes the following steps:

[0070] Step 1: Depositing a substrate 12 on a wafer 11, the material of the substrate 12 is silicon dioxide, forming a substrate 2 for photolithography. The thickness of the substrate 12 is

[0071] Step 2: Spin-coat three layers of photoresist material on the substrate 2, namely, a spin-coated organic bottom structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5. The material of the organic bottom structure layer 3 is SOC, and the material of the silicon-based hard mask intermediate structure layer 4 is SiBARC. The thickness of the organic bottom structure layer 3 is 125nm, the thickness of the silicon-based hard mask intermediate structure layer 4 is 40nm, and the thickness of the photoresist layer 5 is 25nm.

[0072] Step three: After the spin coating process of the organic bottom structure layer 3, the silicon-based hard mask intermediate structure layer 4, and the photoresist layer 5 is completed or the photolithography process is completed, each film layer is inspected. If there is no problem, the subsequent process is carried out; if there is a problem, the rework cleaning process disclosed in this disclosure is carried out and step four is entered.

[0073] Step 4: The rework cleaning process includes the following steps:

[0074] Step 41: Use an organic solvent to clean and remove the photoresist layer 5, and the organic solvent is acetone.

[0075] For the first situation: after step 41 is completed, the photoresist layer 5 is completely removed.

[0076] For the second situation: do not perform step 41 and go directly to step 42.

[0077] For the third situation: skip steps 41 and 42 and go directly to step 43.

[0078] Step 42: Perform a first reactive ion etching to remove the silicon-based hard mask intermediate structure layer 4. The etching gas for the first reactive ion etching is CHF3, wherein the flow rate of CHF3 gas is 20 sccm, the etching chamber pressure is 0.1 Pa, and the etching RF power is 40W.

[0079] For the first case: after step 42 is completed, the silicon-based hard mask intermediate structure layer 4 is completely removed.

[0080] For the second situation: after step 42 is completed, the silicon-based hard mask intermediate structure layer 4 is completely removed.

[0081] For the third case: step 42 is usually not performed. However, even if step 42 is performed, since the silicon-based hard mask intermediate structure layer 4 is not spin-coated, there is no silicon-based hard mask intermediate structure layer 4 that needs to be removed in step 42. The etching rate of the first plasma etching on the organic bottom structure layer 3 is low, and only part of the organic bottom structure layer 8 (such as Figure 4 4C ), and the thickness of the organic bottom structure layer 3 is greater than the silicon-based hard mask intermediate structure layer 4, so most of the organic bottom structure layer 3 is not removed and will not affect the structure on the substrate 2.

[0082] Step 43: ICP etching is performed to remove most of the organic underlying structural layer 3, leaving some residual particles 6 that are difficult to remove. The ICP etching gas is O2, the O2 gas flow rate is 30 sccm, the etching chamber pressure is 0.1 Pa, the ICP power is 50 W, the etching RF power is 10 W, and the etching temperature is 8°C.

[0083] For the first to third situations: after step 43 is completed, most of the organic underlying structural layer 3 is removed, but some residual particles 6 remain that are difficult to remove.

[0084] Step 44: A second reactive ion etching (RIE) is performed to reduce the contact area between the residual particles 6 and the substrate 2, resulting in obliquely etched residual particles 7, with the bottom of the residual particles 7 forming an inverted trapezoidal shape. The etching gas for the second RIE is O2, the etching angle is 15°, the O2 gas flow rate is 20 sccm, the etching chamber pressure is 0.1 Pa, and the etching power is 40 W.

[0085] For the first to third situations: after step 44 is completed, an inverted trapezoid is formed below the residual particles 7 after the oblique etching.

[0086] Step 45: Soak the substrate 2 obtained in step 44 in an organic solvent for 5 to 10 minutes, and then ultrasonically clean it in deionized water to remove basic organic particles. The organic solvent is acetone.

[0087] Step 46: Soak the substrate 2 obtained in step 45 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide for 30 minutes, and use deionized water for bubbling cleaning three times to remove residual particles 7 after the oblique etching. The ratio of the mixed solution is 3:1 and the temperature is 150°C.

[0088] For the first to third situations: after step 46 is completed, some remaining SOC particles and other particles are removed.

[0089] like Figure 5 As shown, the cross-sectional morphology of the wafer before rework cleaning is as follows Figure 5 As shown in Figure 5A, the cross-sectional morphology of the wafer after rework and cleaning is as follows: Figure 5 As shown in Figure 5B, the top view of the surface (after the second reactive ion etching) is as follows Figure 5 As shown in 5D, the standard for wafer reuse can be achieved.

[0090] Example 2:

[0091] The rework cleaning method of the photolithographic structure on the substrate in this embodiment includes the following steps:

[0092] Step 1: Take a clean and uncontaminated pure silicon wafer 11 as the substrate 2 for the photolithography process.

[0093] Step 2: Spin-coat three layers of photoresist material on the substrate 2, namely, a spin-coated organic bottom structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5, wherein the thickness of the organic bottom structure layer 3 is 50nm, the thickness of the silicon-based hard mask intermediate structure layer 4 is 10nm, and the thickness of the photoresist layer 5 is 60nm.

[0094] Step three: After the spin coating process of the organic bottom structure layer 3, the silicon-based hard mask intermediate structure layer 4, and the photoresist layer 5 is completed or the photolithography process is completed, each film layer is inspected. If there is no problem, the subsequent process is carried out; if there is a problem, the rework and cleaning process disclosed in this disclosure is carried out and step four is entered.

[0095] Step 4: The rework cleaning process includes the following steps:

[0096] Step 41: Use an organic solvent to clean and remove the photoresist layer 5, and the organic solvent is N-methylpyrrolidone.

[0097] For the first situation: after step 41 is completed, the photoresist layer 5 is completely removed.

[0098] For the second situation: do not perform step 41 and go directly to step 42.

[0099] For the third situation: skip steps 41 and 42 and go directly to step 43.

[0100] Step 42: Perform a first reactive ion etching to remove the silicon-based hard mask intermediate structure layer 4. The etching gas for the first reactive ion etching is CHF3, wherein the flow rate of CHF3 gas is 60 sccm, the etching chamber pressure is 5 Pa, and the etching RF power is 70 W.

[0101] For the first and second situations: after step 42 is completed, the silicon-based hard mask intermediate structure layer 4 is completely removed.

[0102] Step 43: ICP etching is performed to remove most of the organic underlying structural layer 3, leaving some residual particles 6 that are difficult to remove. The ICP etching gas is O2, the O2 gas flow rate is 65 sccm, the etching chamber pressure is 5 Pa, the ICP power is 100 W, the etching RF power is 30 W, and the etching temperature is 9°C.

[0103] For the first to third situations: after step 43 is completed, most of the organic underlying structural layer 3 is removed, but some residual particles 6 remain that are difficult to remove.

[0104] Step 44: A second reactive ion etching (RIE) is performed to reduce the contact area between the residual particles 6 and the substrate 2, resulting in obliquely etched residual particles 7, with the bottom of the residual particles 7 forming an inverted trapezoidal shape. The etching gas for the second RIE is O2, the etching angle is 45°, the O2 gas flow rate is 60 sccm, the etching chamber pressure is 5 Pa, and the etching power is 70 W.

[0105] For the first to third situations: after step 44 is completed, an inverted trapezoid is formed below the residual particles 7 after the oblique etching.

[0106] Step 45: Soak the substrate 2 obtained in step 44 in an organic solvent for 5 to 10 minutes, and then ultrasonically clean it in deionized water to remove basic organic particles. The organic solvent is acetone.

[0107] Step 46: Soak the substrate 2 obtained in step 45 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide for 40 minutes, and use deionized water for bubbling cleaning three times to remove residual particles 7 after the oblique etching. The ratio of the mixed solution is 6:1 and the temperature is 125°C.

[0108] For the first to third situations: after step 46 is completed, some remaining SOC particles and other particles are removed.

[0109] After rework cleaning, the wafer surface is clean and can meet the standards for wafer reuse.

[0110] Example 3:

[0111] The rework cleaning method of the photolithographic structure on the substrate in this embodiment includes the following steps:

[0112] Step 1: Deposit a base 12 on the wafer 11. The base 12 is made of a polysilicon layer to form a substrate 2 for photolithography. The thickness of the base 12 is

[0113] Step 2: Spin-coat three layers of photoresist material on the substrate 2, namely, a spin-coated organic bottom structure layer 3, a silicon-based hard mask intermediate structure layer 4, and a photoresist layer 5, wherein the thickness of the organic bottom structure layer 3 is 200nm, the thickness of the silicon-based hard mask intermediate structure layer 4 is 50nm, and the thickness of the photoresist layer 5 is 100nm.

[0114] Step three: After the spin coating process of the organic bottom structure layer 3, the silicon-based hard mask intermediate structure layer 4, and the photoresist layer 5 is completed or the photolithography process is completed, each film layer is inspected. If there is no problem, the subsequent process is carried out; if there is a problem, the rework and cleaning process disclosed in this disclosure is carried out and step four is entered.

[0115] Step 4: The rework cleaning process includes the following steps:

[0116] Step 41: Use an organic solvent to clean and remove the photoresist layer 5. The organic solvent includes N-methylpyrrolidone and acetone. First, soak and clean with N-methylpyrrolidone solvent, and then soak and clean with acetone solvent.

[0117] For the first situation: after step 41 is completed, the photoresist layer 5 is completely removed.

[0118] For the second situation: do not perform step 41 and go directly to step 42.

[0119] For the third situation: skip steps 41 and 42 and go directly to step 43.

[0120] Step 42: Perform a first reactive ion etching to remove the silicon-based hard mask intermediate structure layer 4. The etching gas for the first reactive ion etching is CHF3, wherein the flow rate of CHF3 gas is 100 sccm, the etching chamber pressure is 10 Pa, and the etching RF power is 100 W.

[0121] For the first and second situations: after step 42 is completed, the silicon-based hard mask intermediate structure layer 4 is completely removed.

[0122] Step 43: Perform ICP etching to remove most of the organic underlying structural layer 3, leaving some residual particles 6 that are difficult to remove. The ICP etching gas is O2, the O2 gas flow rate is 100 sccm, the etching chamber pressure is 10 Pa, the ICP power is 150 W, the etching RF power is 50 W, and the etching temperature is 10°C.

[0123] For the first to third situations: after step 43 is completed, most of the organic underlying structural layer 3 is removed, but some residual particles 6 remain that are difficult to remove.

[0124] Step 44: A second reactive ion etching (RIE) is performed to reduce the contact area between the residual particles 6 and the substrate 2, resulting in obliquely etched residual particles 7, with the bottom of the residual particles 7 forming an inverted trapezoidal shape. The etching gas for the second RIE is O2, the etching angle is 75°, the O2 gas flow rate is 100 sccm, the etching chamber pressure is 10 Pa, and the etching power is 100 W.

[0125] For the first to third situations: after step 44 is completed, an inverted trapezoid is formed below the residual particles 7 after the oblique etching.

[0126] Step 45: Soak the substrate 2 obtained in step 44 in an organic solvent for 5 to 10 minutes, and then ultrasonically clean it in deionized water to remove basic organic particles. The organic solvent is anhydrous ethanol.

[0127] Step 46: Soak the substrate 2 obtained in step 45 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide for 50 minutes, and use deionized water for bubbling cleaning three times to remove residual particles 7 after the oblique etching. The ratio of the mixed solution is 10:1 and the temperature is 100°C.

[0128] For the first to third situations: after step 46 is completed, some remaining SOC particles and other particles are removed.

[0129] After rework cleaning, the wafer surface is clean and can meet the standards for wafer reuse.

[0130] Comparative Example 1:

[0131] The difference from the solution of the above embodiment 1 is that step 44 is not performed, and the other steps are the same as those of the above embodiment 1. Some particles remain on the surface of the substrate after rework cleaning and cannot be completely removed. Figure 5 As shown, the SEM image after rework cleaning (without the second reactive ion etching) is as follows Figure 5 As shown in 5C, the conditions for reusing the substrate cannot be met.

[0132] The present invention etches the residual particles (including the residual SOC carbonized after high-temperature baking and ICP etching) into an inverted trapezoid through a second reactive ion tilted etching, thereby reducing the contact area between the residual particles and the substrate surface, which is conducive to the subsequent use of solvents to clean and remove the residual particles on the substrate surface, and the O2 plasma etching will not adversely affect the substrate. In addition, the present invention mainly adopts one organic solvent cleaning, two reactive ion etchings with CHF3 and O2 etching gases respectively, one ICP etching with O2 etching gas and one single-wafer cleaning process for the rework cleaning of the photolithographic structure on the substrate. This rework cleaning process can be performed after all three layers of photolithographic materials are formed, and can also be applied to rework after one or two layers of photolithographic materials are formed in the three layers of photolithographic materials. Each process step will not adversely affect the structure on the substrate. Therefore, the rework cleaning method of the present invention is applicable to situations where problems occur in any step of the photolithographic process, and the ICP etching rate is fast, the etching uniformity of a large area is good, and the pollution is small, which can reduce the defects introduced by the rework process.

[0133] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure comprises, from bottom to top, a substrate (2), an organic bottom structure layer (3), a silicon-based hard mask intermediate structure layer (4), and a photoresist layer (5), characterized in that: include: S1, removing the photoresist layer (5) by dry etching or wet cleaning; S2, removing the silicon-based hard mask intermediate structure layer (4) by reactive ion etching; S3, removing the organic bottom structure layer (3) by inductively coupled plasma etching; S4, performing oblique etching on the residual particles (6) on the surface of the substrate (2) by using reactive ion etching to reduce the contact area between the residual particles (6) and the substrate (2), thereby obtaining residual particles (7) after oblique etching; etching the longitudinal section or the lower part of the longitudinal section of the residual particles (6) on the surface of the substrate (2) into an inverted trapezoidal shape by using reactive ion etching; S5, sequentially immersing the substrate (2) obtained in S4 in an organic solvent and washing it in deionized water; S6, soaking the substrate (2) obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles (7) after the oblique etching; and then washing with deionized water to complete the rework cleaning process.

2. The rework cleaning method for a photolithographic structure on a substrate according to claim 1, characterized in that: The solvent used for the wet cleaning in S1 includes one or more of acetone and N-methylpyrrolidone.

3. The rework cleaning method for a photolithographic structure on a substrate according to claim 1, characterized in that: The material of the silicon-based hard mask intermediate structure layer (4) in S2 includes an anti-reflective coating containing Si; The etching gas used in the reactive ion etching in S2 is CHF3, the flow rate of the etching gas is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W.

4. The rework cleaning method for a photolithographic structure on a substrate according to claim 1, characterized in that: The material of the organic underlying structural layer (3) in S3 includes spin-coated organic carbon; The etching gas used in the inductively coupled plasma etching in S3 includes at least O2, the flow rate of the etching gas is 30~100 sccm, the etching chamber pressure is 0.1~10 Pa, the etching power is 50~150 W, the etching RF power is 10~50 W, and the etching temperature is 8~10°C.

5. The rework cleaning method for a photolithographic structure on a substrate according to claim 1, characterized in that: The S4 includes: The substrate (2) is rotated so that the reactive ion source is tilted relative to the surface of the substrate (2), and the residual particles (6) on the surface of the substrate (2) are tilted and etched using reactive ion etching; wherein the tilt angle is 15-75°.

6. The rework cleaning method for a photolithographic structure on a substrate according to claim 5, characterized in that: The etching gas used in the reactive ion etching in S4 is O2, the flow rate of the etching gas is 20-100 sccm, the etching chamber pressure is 0.1-10 Pa, and the etching power is 40-100 W.

7. The rework cleaning method for a photolithographic structure on a substrate according to claim 1, characterized in that: The immersion time in the organic solvent in S5 is 5 to 10 minutes, and the organic solvent includes one or more of ethanol, acetone and N-methylpyrrolidone; The temperature of the concentrated sulfuric acid and hydrogen peroxide mixed solution heated in S6 is 100-150°C, the molar ratio of the concentrated sulfuric acid to hydrogen peroxide is 3:1-10:1, and the soaking time is 30-60 min; The S5 and the S6 adopt a single-wafer cleaning method.

8. A rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure comprises, from bottom to top, a substrate (2), an organic bottom structure layer (3), and a silicon-based hard mask intermediate structure layer (4), characterized in that: include: S2, removing the silicon-based hard mask intermediate structure layer (4) by reactive ion etching; S3, removing the organic bottom structure layer (3) by inductively coupled plasma etching; S4, performing oblique etching on the residual particles (6) on the surface of the substrate (2) by using reactive ion etching to reduce the contact area between the residual particles (6) and the substrate (2), thereby obtaining residual particles (7) after oblique etching; etching the longitudinal section or the lower part of the longitudinal section of the residual particles (6) on the surface of the substrate (2) into an inverted trapezoidal shape by using reactive ion etching; S5, sequentially immersing the substrate (2) obtained in S4 in an organic solvent and washing it in deionized water; S6, soaking the substrate (2) obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles (7) after the oblique etching; and then washing with deionized water to complete the rework cleaning process.

9. A rework cleaning method for a photolithographic structure on a substrate, wherein the reworked photolithographic structure comprises, from bottom to top, a substrate (2) and an organic underlying structure layer (3), characterized in that: include: S3, removing the organic bottom structure layer (3) by inductively coupled plasma etching; S4, performing oblique etching on the residual particles (6) on the surface of the substrate (2) by using reactive ion etching to reduce the contact area between the residual particles (6) and the substrate (2), thereby obtaining residual particles (7) after oblique etching; etching the longitudinal section or the lower part of the longitudinal section of the residual particles (6) on the surface of the substrate (2) into an inverted trapezoidal shape by using reactive ion etching; S5, sequentially immersing the substrate (2) obtained in S4 in an organic solvent and washing it in deionized water; S6, soaking the substrate (2) obtained in S5 in a heated mixed solution of concentrated sulfuric acid and hydrogen peroxide to remove the residual particles (7) after the oblique etching; and then washing with deionized water to complete the rework cleaning process.

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