A method for repairing surface defects of a silicon wafer and enhancing performance of photoresist

Abstract

The application discloses a method for repairing defects on a silicon wafer surface and enhancing photoresist performance, aiming at solving the problems of poor defect repairing effect and weak bonding force between the photoresist and the silicon wafer in the prior art. The method comprises the following steps: sequentially performing plasma pretreatment, defect-selective silicon dioxide repairing layer deposition, photoresist enhancing layer construction, catalytic cross-linking and photoresist application, and optionally adding plasma light treatment to activate silicon hydroxyl. The application can precisely fill and level the defects on the silicon wafer, significantly improve the bonding force of the photoresist through covalent cross-linking, has good process compatibility, can guarantee the stability of subsequent semiconductor processes, and improve the device yield and reliability. The application also relates to a silicon wafer treated by the method and a semiconductor device manufacturing method comprising the treatment steps.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to a method for repairing surface defects on silicon wafers and enhancing the performance of photoresists, and also to silicon wafers treated by this method and a semiconductor device manufacturing method including this treatment step. Background Technology

[0002] In semiconductor device manufacturing, silicon wafers, as the core substrate material, directly determine the precision of subsequent processes such as photolithography, etching, and ion implantation, as well as the performance of the final device. However, during the early processing of silicon wafers, such as cutting, grinding, and polishing, surface defects such as microcracks, scratches, and pits are inevitably generated. These defects not only lead to uneven photoresist coating but may also become stress concentration points in subsequent processes, causing problems such as photoresist detachment and etching deviations, seriously affecting the yield and reliability of the device.

[0003] Existing technologies for repairing defects on silicon wafer surfaces mainly include chemical mechanical polishing (CMP) and wet etching. While CMP can improve surface smoothness, its effectiveness in repairing defects such as microcracks is limited, and it may introduce new impurities. Wet etching, on the other hand, suffers from poor etching anisotropy, easily leading to distortion of the silicon wafer surface morphology. Furthermore, in existing technologies, the bonding between photoresist and the silicon wafer surface largely relies on physical adsorption, resulting in weak adhesion. This makes photoresist peeling and warping highly susceptible to occur during subsequent development and etching processes, further limiting the development of semiconductor devices towards higher precision and higher density.

[0004] To address the aforementioned issues, there is an urgent need to develop a method that can precisely repair defects on the silicon wafer surface while significantly enhancing the adhesion between the photoresist and the silicon wafer surface, in order to meet the requirements of advanced semiconductor manufacturing processes. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for repairing defects on the surface of silicon wafers and enhancing the performance of photoresist.

[0006] To achieve the aforementioned objective, the technical solution of the present invention is implemented as follows: a method for repairing surface defects on silicon wafers and enhancing the performance of photoresist, comprising the following steps: S1. Plasma pretreatment The silicon wafer to be processed is placed in a plasma processing chamber, and a process gas containing fluorine and / or chlorine is introduced to generate plasma, which is used to perform anisotropic etching and cleaning on the surface of the silicon wafer.

[0007] In this step, inductively coupled plasma or capacitively coupled plasma is used. This type of plasma has the advantages of high plasma density and good etching directionality, enabling precise anisotropic etching of the silicon wafer surface. The process gas is one or more of CF4, CHF3, C4F8, Cl2, and HBr mixed with Ar and O2. The fluorine / chlorine-containing gas reacts with impurities and defects on the silicon wafer surface, achieving etching and cleaning. Ar, as a dilution and bombardment gas, enhances the etching effect of the plasma. O2 oxidizes and removes organic contaminants from the silicon wafer surface. Specific process parameters are controlled as follows: processing pressure 1-100 mTorr, RF power 50-1000 W, and processing time 5-60 seconds. By precisely controlling these parameters, the silicon wafer surface can be cleaned while avoiding over-etching that could damage the surface.

[0008] S2. Deposition of Defect Selective Repair Layer On the silicon wafer surface treated in step S1, a silicon source precursor and an oxidant are introduced into a reaction chamber with controllable temperature and pressure. A silicon dioxide repair layer is selectively deposited on the silicon wafer surface through atomic layer deposition or plasma-enhanced chemical vapor deposition. The deposition process parameters cause the silicon dioxide repair layer to preferentially nucleate and grow at surface defects until the defects are filled.

[0009] In this step, tetraethoxysilane, tetramethylcyclotetrasiloxane, or di-tert-butylaminosilane are selected as silicon source precursors. These precursors have moderate reactivity and high film quality. O3, H2O, or O2 plasma are selected as oxidants, which can react with the silicon source precursor to generate silicon dioxide. The deposition temperature is controlled at 50-300℃, and the reaction pressure is controlled at 0.1-10 Torr. This temperature and pressure range ensures sufficient decomposition and reaction of the precursor while avoiding damage to the silicon wafer caused by high temperature and high pressure.

[0010] If atomic layer deposition (ALD) is used, a single cycle includes: pulsed silicon source precursor – purge – pulsed oxidant – purge, with 10-500 cycles to obtain a 5-100 nm thick silica repair layer. ALD offers excellent step coverage and thickness control. By controlling the number of cycles, the repair layer thickness can be precisely adjusted, ensuring complete defect filling without affecting the overall flatness of the silicon wafer surface. The purge step removes unreacted precursors and byproducts from the reaction chamber, preventing impurity defects. If plasma-enhanced chemical vapor deposition (PECVD) is used, selective growth of the repair layer at the defect site can be achieved by adjusting the plasma power and gas flow rate.

[0011] S3. Construction of photoresist reinforcement layer On the silica repair layer formed in step S2, a layer of organosiloxane polymer solution is coated by spin coating, followed by low-temperature baking to form a photoresist reinforcement layer with a silicon hydroxyl enriched surface.

[0012] In this step, the organosiloxane polymer selected is a functionalized siloxane containing epoxy, amino, or mercapto groups, with a molecular weight of 1000-10000 g / mol. The functional groups in this type of polymer molecule can react with the functional groups of the subsequent photoresist, and the silicon-oxygen bonds in its molecular chain have excellent stability. The solvent selected for the solution is propylene glycol methyl ether acetate, ethyl lactate, or cyclohexanone. These solvents have good solubility for the organosiloxane polymer and a moderate evaporation rate, which can ensure the uniformity of the solution during spin coating. The solid content of the solution is controlled at 0.5%-5% wt to ensure that the formed reinforcing layer has uniform thickness and stable performance.

[0013] After spin coating, a low-temperature baking process is performed at 80-180℃ for 60-120 seconds. The purpose of this low-temperature baking is to remove the solvent from the solution, allowing the organosiloxane polymer to solidify and form a dense reinforcing layer, while avoiding polymer chain decomposition caused by high temperatures. The final photoresist reinforcing layer has a thickness of 2-20 nm. This thickness range ensures both the density and stability of the reinforcing layer without affecting the resolution of subsequent photolithography processes.

[0014] S3a. Optional plasma light treatment steps Between steps S3 and S4, a step of lightly treating the photoresist reinforcement layer with helium or nitrogen plasma may be included. The treatment power is 50-300 W, and the time is 1-30 seconds. Helium and nitrogen are both inert gases and will not chemically react with the reinforcement layer. Through plasma treatment, the silanol groups on the surface of the reinforcement layer can be further activated, increasing the number and activity of silanol groups, providing more active sites for the subsequent crosslinking reaction with the photoresist, and further improving the adhesion.

[0015] S4. Catalytic Crosslinking and Photoresist Applications Photoresist is coated on the surface of the photoresist reinforcement layer. By ultraviolet light irradiation or thermal catalysis, the silanol groups in the photoresist reinforcement layer and the functional groups in the photoresist substrate undergo a covalent cross-linking reaction, thereby achieving a strong bond between the photoresist and the silicon wafer surface.

[0016] In this step, the wavelength of ultraviolet irradiation is selected as 172nm, 222nm, or 254nm, and the irradiation dose is 10-1000 mJ / cm². Ultraviolet light in this wavelength range can effectively activate the reactivity of silanol groups and photoresist functional groups. The thermal catalysis temperature is controlled at 80-150℃ for 30-180 seconds, and the cross-linking reaction is initiated by thermal energy. Through ultraviolet irradiation or thermal catalysis, the silanol groups in the photoresist reinforcement layer undergo covalent cross-linking reactions with the carboxyl groups, epoxy groups, and other functional groups in the photoresist substrate, forming stable chemical bonds. Compared with traditional physical adsorption, the bonding force is significantly improved, effectively avoiding the problems of photoresist detachment and warping in subsequent processes.

[0017] Furthermore, the present invention also provides a silicon wafer whose surface is treated by any of the methods described above, having a silicon dioxide repair layer for filling surface defects and an organosiloxane reinforcement layer covalently bonded to photoresist. This silicon wafer exhibits high surface flatness, low defect rate, and excellent photoresist bonding performance, meeting the requirements of advanced semiconductor manufacturing processes.

[0018] Furthermore, this invention also provides a method for manufacturing a semiconductor device, comprising processing a silicon wafer substrate using any of the methods described above, followed by semiconductor manufacturing process steps such as photolithography, etching, ion implantation, or thin film deposition. By pre-treating the silicon wafer substrate, the accuracy and stability of subsequent processes are significantly improved, effectively enhancing the yield and performance of the semiconductor device.

[0019] The beneficial effects of this invention are reflected in: Precise and efficient repair effect: This invention achieves cleaning and activation of the silicon wafer surface through plasma pretreatment, and then selectively deposits a silicon dioxide repair layer using atomic layer deposition or plasma-enhanced chemical vapor deposition process. It can accurately nucleate and grow at the defect site until the defect is filled, resulting in excellent repair effect without affecting the overall flatness of the silicon wafer surface.

[0020] Significantly enhanced photoresist adhesion: By constructing an organosiloxane polymer photoresist reinforcement layer and initiating a cross-linking reaction using ultraviolet light irradiation or thermal catalysis, a stable covalent bond is formed between the photoresist and the reinforcement layer. Compared with traditional physical adsorption, the adhesion is greatly improved, effectively avoiding problems such as photoresist detachment and warping in subsequent processes.

[0021] Good process compatibility: The process parameters of each step of the present invention are mild, and the process equipment and materials used are all conventional equipment and materials in the semiconductor manufacturing field. There is no need to introduce special equipment and processes, and it can be perfectly compatible with existing semiconductor manufacturing processes, making it easy to promote and apply industrially.

[0022] Improving device yield and performance: The silicon wafers treated by the method of this invention have excellent surface quality and strong photoresist adhesion, which can ensure the accuracy of subsequent photolithography, etching and other processes, effectively reduce the defect rate of devices, and improve the yield and reliability of semiconductor devices. Attached Figure Description

[0023] In the attached diagram: Figure 1 This is an overall flowchart of the method of the present invention; Figure 2 Here is the logic diagram of the S1 plasma pretreatment process parameters; Figure 3 Here is the logic diagram of the S2 defect selective repair layer deposition process; Figure 4 The diagram shows the logic of the photoresist enhancement and crosslinking process for S3~S4. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that if the embodiments of the invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, "multiple" refers to two or more. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0027] Please refer to the instruction manual appendix. Figures 1-4 Example

[0028] A method for repairing surface defects on silicon wafers and enhancing the performance of photoresist includes the following steps: S1. Plasma pretreatment: The silicon wafer to be treated is placed in the inductively coupled plasma treatment chamber, and process gas (a mixture of CF4 and Ar in a volume ratio of 1:3) is introduced. The treatment pressure is 50 mTorr, the radio frequency power is 500 W, and the treatment time is 30 seconds to perform anisotropic etching and cleaning on the surface of the silicon wafer.

[0029] S2. Deposition of Defect-Selective Repair Layer: The silicon wafer treated in step S1 is transferred to the atomic layer deposition reaction chamber. The chamber temperature is controlled at 150°C and the reaction pressure is 1 Torr. The silicon source precursor tetraethoxysilane and oxidant O3 are introduced. The silicon dioxide repair layer is deposited using the atomic layer deposition process. A single cycle is: pulsed tetraethoxysilane (pulse time 0.5 seconds) - purge (purge time 2 seconds) - pulsed O3 (pulse time 0.5 seconds) - purge (purge time 2 seconds). The number of cycles is 200 times to form a silicon dioxide repair layer with a thickness of 50 nm. This repair layer preferentially nucleates and grows at the defects on the silicon wafer surface, completely filling the defects.

[0030] S3. Construction of photoresist reinforcement layer: A solution of organosiloxane polymer containing epoxy groups (solvent is propylene glycol methyl ether acetate, solid content is 2% wt, polymer molecular weight is 5000 g / mol) was coated on the surface of the silica repair layer using a spin coating process at a speed of 3000 rpm. Then, it was baked at 120℃ for 90 seconds to form a photoresist reinforcement layer with a thickness of 10 nm.

[0031] S4. Catalytic crosslinking and photoresist application: Photoresist is coated on the surface of the photoresist reinforcement layer and irradiated with ultraviolet light at a wavelength of 254nm and an irradiation dose of 500 mJ / cm². This initiates a covalent crosslinking reaction between the silanol groups in the reinforcement layer and the carboxyl groups in the photoresist substrate, achieving a strong bond between the photoresist and the silicon wafer surface. Example

[0032] A method for repairing surface defects on silicon wafers and enhancing the performance of photoresist includes the following steps: S1. Plasma pretreatment: The silicon wafer to be treated is placed in the capacitively coupled plasma treatment chamber, and process gas (a mixture of Cl2, HBr and O2 in a volume ratio of 2:1:1) is introduced. The treatment pressure is 10 mTorr, the RF power is 800 W, and the treatment time is 10 seconds to perform anisotropic etching and cleaning on the surface of the silicon wafer.

[0033] S2. Deposition of Defect-Selective Repair Layer: The silicon wafer treated in step S1 is transferred to a plasma-enhanced chemical vapor deposition reaction chamber. The chamber temperature is controlled at 250°C and the reaction pressure is 5 Torr. A silicon source precursor tetramethylcyclotetrasiloxane and an oxidant O2 plasma are introduced to deposit a silicon dioxide repair layer until the defects on the silicon wafer surface are completely filled. The thickness of the repair layer is 80 nm.

[0034] S3. Photoresist reinforcement layer construction: An amino-containing organosiloxane polymer solution (solvent is ethyl lactate, solid content is 4% wt, polymer molecular weight is 8000 g / mol) was coated on the surface of the silica repair layer using a spin coating process at a speed of 2500 rpm. Subsequently, it was baked at a low temperature of 160℃ for 60 seconds to form a photoresist reinforcement layer with a thickness of 15 nm.

[0035] S3a. Plasma light treatment: The photoresist reinforcement layer is lightly treated with helium plasma at a power of 200 W for 15 seconds to activate the surface silanol groups.

[0036] S4. Catalytic crosslinking and photoresist application: Photoresist is coated on the surface of the photoresist reinforcement layer. A thermocatalytic method is used, with the temperature controlled at 120℃ and the holding time at 120 seconds, which triggers the covalent crosslinking reaction between the silanol groups in the reinforcement layer and the epoxy groups in the photoresist substrate, thereby achieving a strong bond between the photoresist and the silicon wafer surface. Example

[0037] A method for repairing surface defects on silicon wafers and enhancing the performance of photoresist includes the following steps: S1. Plasma pretreatment: The silicon wafer to be treated is placed in the inductively coupled plasma treatment chamber, and process gas (a mixture of C4F8 and Ar and O2 in a volume ratio of 1:4:1) is introduced. The treatment pressure is 80 mTorr, the radio frequency power is 200 W, and the treatment time is 50 seconds to perform anisotropic etching and cleaning on the surface of the silicon wafer.

[0038] S2. Deposition of Defect-Selective Repair Layer: The silicon wafer treated in step S1 is transferred to the atomic layer deposition reaction chamber. The chamber temperature is controlled at 80°C and the reaction pressure is 0.5 Torr. The silicon source precursor di-tert-butylaminosilane and the oxidant H2O are introduced. The silica repair layer is deposited using the atomic layer deposition process. A single cycle is: pulse di-tert-butylaminosilane (pulse time 0.8 seconds) - purge (purge time 3 seconds) - pulse H2O (pulse time 0.8 seconds) - purge (purge time 3 seconds). The number of cycles is 80 times to form a silica repair layer with a thickness of 20 nm, which completely fills the defects.

[0039] S3. Photoresist reinforcement layer construction: A solution of organosiloxane polymer containing thiol groups (solvent is cyclohexanone, solid content is 1% wt, polymer molecular weight is 2000 g / mol) was coated on the surface of the silica repair layer using a spin coating process at a speed of 3500 rpm. Then, it was baked at 90℃ for 120 seconds to form a photoresist reinforcement layer with a thickness of 5 nm.

[0040] S3a. Plasma light treatment: The photoresist reinforcement layer is lightly treated with nitrogen plasma at a power of 100 W for 25 seconds to activate the surface silanol groups.

[0041] S4. Catalytic crosslinking and photoresist application: Photoresist is coated on the surface of the photoresist reinforcement layer and irradiated with ultraviolet light at a wavelength of 172nm and an irradiation dose of 200 mJ / cm². This initiates a covalent crosslinking reaction between the silanol groups in the reinforcement layer and the functional groups in the photoresist substrate, thereby achieving a strong bond between the photoresist and the silicon wafer surface.

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

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for repairing surface defects and enhancing photoresist performance on silicon wafers, characterized in that... The process includes the following steps: S1. Plasma pretreatment: The silicon wafer to be treated is placed in the plasma treatment chamber, and a process gas containing fluorine and / or chlorine is introduced to generate plasma, which is used to perform anisotropic etching and cleaning on the surface of the silicon wafer. S2. Deposition of a selective defect repair layer: On the silicon wafer surface treated in step S1, a silicon source precursor and an oxidant are introduced into a reaction chamber with controlled temperature and pressure. A silicon dioxide repair layer is selectively deposited on the silicon wafer surface using atomic layer deposition or plasma-enhanced chemical vapor deposition. The deposition process parameters cause the silicon dioxide repair layer to preferentially nucleate and grow at surface defects until the defects are filled. S3. Photoresist reinforcement layer construction: On the silicon dioxide repair layer formed in step S2, a layer of organosiloxane polymer solution is coated by spin coating process, followed by low temperature baking to form a photoresist reinforcement layer with a silicon hydroxyl enriched surface; S4. Catalytic crosslinking and photoresist application: Photoresist is coated on the surface of the photoresist reinforcement layer. By ultraviolet light irradiation or thermal catalysis, the silanol groups in the photoresist reinforcement layer and the functional groups in the photoresist substrate undergo a covalent crosslinking reaction, thereby achieving a strong bond between the photoresist and the silicon wafer surface.

2. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, In step S1, the plasma is inductively coupled plasma or capacitively coupled plasma, the process gas is one or more of CF4, CHF3, C4F8, Cl2, and HBr mixed with Ar and O2, the processing pressure is 1-100 mTorr, the radio frequency power is 50-1000 W, and the processing time is 5-60 seconds.

3. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, In step S2, the silicon source precursor is tetraethoxysilane, tetramethylcyclotetrasiloxane, or di-tert-butylaminosilane, and the oxidant is O3, H2O, or O2 plasma; the deposition temperature is 50-300℃, and the reaction pressure is 0.1-10 Torr.

4. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, In step S2, a single cycle of atomic layer deposition includes: pulsed silicon source precursor—purge—pulsed oxidant—purge, with 10-500 cycles to obtain a 5-100 nm thick silicon dioxide repair layer.

5. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, In step S3, the organosiloxane polymer is a functionalized siloxane containing epoxy, amino, or mercapto groups, with a molecular weight of 1000-10000 g / mol; the solvent of the solution is propylene glycol methyl ether acetate, ethyl lactate, or cyclohexanone, with a solid content of 0.5%-5% wt; the low-temperature baking temperature is 80-180℃, and the time is 60-120 seconds.

6. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, The thickness of the photoresist enhancement layer formed in step S3 is 2-20 nm.

7. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, In step S4, the wavelength of the ultraviolet irradiation is 172nm, 222nm, or 254nm, and the irradiation dose is 10-1000 mJ / cm²; the thermal catalysis temperature is 80-150℃, and the time is 30-180 seconds.

8. The method for repairing surface defects and enhancing photoresist performance on silicon wafers according to claim 1, characterized in that, Between steps S3 and S4, there is also step S3a: lightly treating the photoresist reinforcement layer with helium or nitrogen plasma at a power of 50-300 W for 1-30 seconds to further activate the silanol groups on its surface.

9. A silicon wafer, characterized in that, Its surface is treated by any one of claims 1-8, and has a silica repair layer that fills surface defects and an organosiloxane reinforcement layer that is covalently bonded to the photoresist.

10. A method for manufacturing a semiconductor device, characterized in that, This includes processing a silicon wafer substrate using the method described in any one of claims 1-8, followed by semiconductor manufacturing process steps such as photolithography, etching, ion implantation, or thin film deposition.

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