Method for reducing particle pollution generated by semiconductor static pipeline system

Abstract

The invention belongs to the technical field of semiconductor processing, and particularly relates to a method for reducing particle pollution generated by a semiconductor static pipeline system. The static pipeline system refers to all fixed and non-dynamically adjusted gas conveying channels, connecting pieces and mounting structures of the gas conveying channels, the connecting pieces and the mounting structures, the gas conveying channels, the connecting pieces and the mounting structures are arranged between a mass flow controller and a reaction chamber flange in the polycrystalline silicon deposition equipment, and the static pipeline is made of stainless steel. And carrying out oxidation passivation operation on the static pipeline system to deposit passivation layers on the inner walls of the pipelines, the connecting pieces and the surfaces of the mounting structures, which are in contact with the gas source gas for polycrystalline silicon deposition, and then carrying out a polycrystalline silicon deposition process. The compact oxide layer is formed in the pipeline, so that the particle release amount is greatly reduced, the number of particles entering the reaction chamber is further reduced, and the subsequent polycrystalline silicon thin film deposition quality is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor processing technology, and specifically relates to a method for reducing particulate contamination generated in semiconductor static piping systems. Background Technology

[0002] In semiconductor manufacturing, polysilicon deposition is a critical step, and its quality directly affects the electrical performance and reliability of devices. The static piping (referring to piping that is not frequently switched on and off and remains in a relatively stable state for extended periods) between the mass flow controller (MFC) and the flange in the polysilicon deposition equipment, as well as the valves within the piping (such as pneumatic valves and manual valves), are among the main sources of particulate contamination.

[0003] During long-term use, static pipelines and valves are prone to developing particles on their inner walls due to gas erosion, material micro-wear, and surface adsorption of impurities. These particles, once introduced into the reaction chamber by process gases, can lead to increased defects in polycrystalline silicon thin films and device leakage, severely impacting product yield.

[0004] Existing methods for controlling particulate matter mainly include periodic pipeline cleaning, valve replacement, or the use of high-purity materials. However, these methods suffer from high costs, short maintenance cycles, and long equipment downtime. Therefore, there is an urgent need for an efficient and low-cost method to reduce particulate contamination from static pipelines and valves. Summary of the Invention

[0005] To address the aforementioned technical problems, one objective of this invention is to provide a method for reducing particulate contamination in semiconductor static piping systems.

[0006] The technical solution adopted in this invention is as follows: A method for reducing particulate contamination from a semiconductor static piping system, wherein the static piping system comprises all fixed, non-dynamically adjustable gas delivery channels, connectors, and their installation structures located between the mass flow controller and the reaction chamber flange in a polysilicon deposition equipment. The static piping is made of stainless steel. Before each replacement of the static piping system, an oxidation passivation operation is performed on the static piping system to deposit a passivation layer on the inner walls of all pipes, connectors, and installation structures that come into contact with the gas source for polysilicon deposition, before proceeding with the polysilicon deposition process.

[0007] Preferably, the passivation layer has a thickness of 5~50 nm.

[0008] Preferably, it includes the following steps: S1. After shutting off the process gas supply to the polysilicon deposition equipment and isolating the static piping system from the polysilicon deposition reaction chamber, the static piping system is evacuated. S2. Introduce oxygen into the static piping system and then heat the static piping system to form a dense oxide layer on the inner wall of the pipes and the surfaces of the connectors and installation structures; S3. Stop the oxygen supply, evacuate again, and purge with inert gas or nitrogen until the static pipeline system returns to normal pressure or the reference pressure required by the process. S4. Restore the connection between the static piping system and the polysilicon deposition reaction chamber, and put the polysilicon deposition equipment into normal operation.

[0009] Preferably, in step S1, the vacuum level is controlled at 1×10⁻⁶ during the vacuuming process. -3 Pa to 5×10 -3 Between 10 and 30 Pa, duration 10-30 min.

[0010] Preferably, in step S2, the oxygen flow rate is 50~200 sccm, the pressure in the static pipeline system is controlled at 10~50 Pa, the heating temperature is 100~300℃, and the passivation time is 2~6 h.

[0011] Preferably, in step S3, the vacuum level during the second vacuuming is controlled at 1×10⁻⁶. -3 Pa to 5×10 -3 Between 10 and 30 Pa, duration 10-30 min.

[0012] Preferably, in step S3, the flow rate of the inert gas or nitrogen is 100~300 sccm, and the duration is 10~20min.

[0013] Preferably, in step S2, the valves in the static pipeline system are kept in a specific state during the passivation process. Specifically, for pneumatic valves, they are controlled to switch between open and closed states every 30 to 60 minutes; for manual valves, they are kept in the normal state of the polysilicon deposition process.

[0014] The beneficial effects of this invention are as follows: In the existing technology, the existing oxygen passivation technology is concentrated in the reaction chamber, while the long-path pipeline (>5m) in the polycrystalline silicon deposition equipment has the following problems: the passivation layer thickness decreases with the length of the pipeline (according to actual measurements of the equipment, the passivation layer thickness at the pipeline outlet is about 32% of that at the inlet), and the oxidation is uneven at the bends / tees (crystal phase analysis shows local Fe2O3 rather than Cr2O3).

[0015] This application breaks with conventional thinking in the industry by applying oxygen passivation technology to static piping systems, controlling the generation of particulate pollutants at the source. It utilizes oxygen at specific temperature and pressure to react with the metal or metal oxides on the surface of static piping and valves, forming a dense oxide layer (which can be Cr2O3, SiO2, etc., depending on the material). This oxide layer has the following characteristics: 1) Covers minor scratches and wear points on the surface of pipes and valves, reducing particles caused by micro-shedding of material; 2) Reduce the surface roughness of pipelines and valves to decrease impurity adsorption sites and inhibit particle formation and adhesion. 3) Improve the surface chemical stability of static piping systems, resist corrosion from process gases, and extend the service life of pipes and valves.

[0016] By utilizing the method provided in this application, a dense oxide layer is formed, which significantly reduces the amount of particles released from static pipelines and valves, thereby reducing the number of particles entering the reaction chamber and improving the quality of subsequent polycrystalline silicon thin film deposition. The particle control effect is remarkable.

[0017] This application does not require the replacement of equipment parts; passivation can be achieved simply by introducing oxygen. It has low material costs and can be completed during regular equipment maintenance, without adding significant downtime or affecting production efficiency.

[0018] This application is applicable to static pipelines (such as stainless steel pipelines) of various polysilicon deposition equipment and various types of valves (pneumatic valves, manual valves, etc.), with a wide range of applications and strong compatibility.

[0019] The passivated oxide layer can maintain a stable effect for 12 months, significantly extending the cycle of pipeline cleaning and valve replacement, and reducing equipment maintenance costs. Attached Figure Description

[0020] Figure 1 The image shows a comparison of the valve before and after passivation. The left side shows the effect before passivation, and the right side shows the effect after passivation using the method of this application. Detailed Implementation

[0021] Unless otherwise stated, the terms used herein have the meanings commonly understood by those skilled in the art.

[0022] The technical solution of the present invention will be described in more detail below: A method for reducing particulate contamination from a semiconductor static piping system, wherein the static piping system comprises all fixed, non-dynamically adjustable gas delivery channels, connectors, and their installation structures located between the mass flow controller and the reaction chamber flange in a polysilicon deposition equipment, and the static piping system is made of stainless steel.

[0023] Before each replacement of the static piping system, an oxidation passivation operation is performed on the static piping system to deposit a passivation layer on the inner walls of all pipes, connectors, and installation structures that come into contact with the gas source gas deposited with polysilicon, and then the polysilicon deposition process is carried out.

[0024] Specifically, it includes the following steps: S1. After shutting off the process gas supply to the polysilicon deposition equipment and isolating the static piping system from the polysilicon deposition reaction chamber, evacuate the static piping system to a vacuum level of 1×10⁻⁶. -3 Pa to 5×10 -3 The pressure is maintained between 10 and 30 Pa for 10 to 30 minutes to remove residual process gases and impurities from the pipeline.

[0025] S2. Introduce high-purity oxygen (purity ≥99.999%) into the static piping system, controlling the oxygen flow rate at 50~200 sccm, and maintain the pressure within the static piping system at 10~50 Pa. Then, use a heating device to maintain the temperature of the static piping system at 100~300℃, and passivate for 2~6 hours, so that a dense oxide layer with a thickness of 5~50 nm is formed on the inner wall of the pipe, the surface of the connectors, and the installation structure.

[0026] During this process, the valves in the static pipeline system must be kept in a specific state: for pneumatic valves, they should be switched between open and closed states every 30 to 60 minutes to ensure that the sealing surface, valve core and other key parts of the valve can be in full contact with oxygen; for manual valves, they should be kept in the normal state of the polysilicon deposition process (such as half open or fully open, as set according to process requirements).

[0027] S3. After passivation is complete, stop the oxygen supply and evacuate the static piping system again, maintaining the vacuum level at 1×10⁻⁶. -3 Pa to 5×10 -3 The pressure is maintained between 10 and 30 Pa for 10 to 30 minutes to remove residual oxygen. Then, inert gas or nitrogen (purity ≥ 99.999%) is introduced into the static pipeline system for purging at a flow rate of 100 to 300 sccm for 10 to 20 minutes until the static pipeline system returns to atmospheric pressure or the reference pressure required for the process. S4. Restore the connection between the static piping system and the polysilicon deposition reaction chamber, and put the polysilicon deposition equipment into normal operation.

[0028] See Figure 1 The left side shows a photo of the valve before passivation, and the right side shows a photo of the valve after passivation. After passivation, a dense oxide layer is formed on the surface of the valve. This oxide layer covers the tiny scratches and wear points on the surface of the valve, which can reduce particles generated by micro-shedding of material; it reduces the surface roughness of the valve, which can reduce the adsorption sites of impurities and inhibit the generation and adhesion of particles; it improves the chemical stability of the valve surface, which can resist the corrosion of process gases to a certain extent and extend its service life.

[0029] The above is merely a general description of the present invention and is not intended to limit the scope of the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for reducing particulate contamination from a semiconductor static piping system, wherein the static piping system comprises all fixed, non-dynamically adjustable gas delivery channels, connectors, and their installation structures disposed between the mass flow controller and the reaction chamber flange in a polysilicon deposition equipment, and the static piping is made of stainless steel, characterized in that, Before each replacement of the static piping system, an oxidation passivation operation is performed on the static piping system to deposit a passivation layer on the inner walls of all pipes, connectors, and installation structures that come into contact with the gas source gas deposited with polysilicon, and then the polysilicon deposition process is carried out.

2. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 1, characterized in that, The passivation layer has a thickness of 5~50 nm.

3. A method for reducing particulate contamination in a semiconductor static piping system as described in claim 1 or 2, characterized in that, Includes the following steps: S1. After shutting off the process gas supply to the polysilicon deposition equipment and isolating the static piping system from the polysilicon deposition reaction chamber, the static piping system is evacuated. S2. Introduce oxygen into the static piping system and then heat the static piping system to form a dense oxide layer on the inner wall of the pipes and the surfaces of the connectors and installation structures; S3. Stop the oxygen supply, evacuate again, and purge with inert gas or nitrogen until the static pipeline system returns to normal pressure or the reference pressure required by the process. S4. Restore the connection between the static piping system and the polysilicon deposition reaction chamber, and put the polysilicon deposition equipment into normal operation.

4. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 3, characterized in that, In step S1, during the vacuuming process, the vacuum level is controlled at 1×10⁻⁶. -3 Pa to 5×10 -3 Between 10 and 30 Pa, duration 10-30 min.

5. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 3, characterized in that, In step S2, the oxygen flow rate is 50~200 sccm, the pressure in the static pipeline system is controlled at 10~50 Pa, the heating temperature is 100~300℃, and the passivation time is 2~6 h.

6. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 3, characterized in that, In step S3, the vacuum level during the second vacuuming is controlled at 1×10⁻⁶. -3 Pa to 5×10 -3 Between Pa, duration 10-30 min.

7. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 3, characterized in that, In step S3, the flow rate of the inert gas or nitrogen is 100~300 sccm, and the duration is 10~20 min.

8. The method for reducing particulate contamination in a semiconductor static piping system as described in claim 3, characterized in that, In step S2, the valves in the static pipeline system are kept in a specific state during the passivation process. Specifically, for pneumatic valves, they are controlled to switch between open and closed states every 30 to 60 minutes; for manual valves, they are kept in the normal state of the polysilicon deposition process.

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