Wafer processing method

Abstract

The wafer processing method provided by the embodiment of the invention is completed by utilizing low-pressure process equipment; the low-pressure process equipment comprises a low-pressure cavity and a transition cabin, the low-pressure cavity is adjacent to the transition cabin, and a low-pressure cavity door is arranged between the low-pressure cavity and the transition cabin; inert gas is introduced into the low-pressure cavity and the transition cabin; when the low-pressure cavity and the transition cabin are both in an idle state and the idle state time is judged to be longer than the preset idle time, before the wafer enters the low-pressure cavity, the inert gas flow of the low-pressure cavity and the transition cabin is controlled, so that the low-pressure cavity and the transition cabin reach a pressure balance state; therefore, the particle problem caused by unbalanced pressure at the moment when the to-be-processed wafer is transferred into the low-pressure cavity from the transition cabin can be avoided, and at the moment, the to-be-processed wafer is processed according to the operation task to obtain the processed wafer. Through the method, the quality and the yield of the wafer can be improved, and the problem of wafer surface particles in a low-pressure process is avoided, so that the stability of the process can be improved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and specifically relates to a wafer processing method. Background Art

[0002] In the wafer processing process, in order to repair the defects of the wafer or semiconductor devices and effectively improve the quality and electrical characteristics of semiconductor devices, the ISSG process (in-situ steam oxidation process) or the PNA process (annealing after nitriding) is usually used. The ISSG process and the PNA process are carried out using the low-pressure chamber in the low-pressure process equipment. In the prior art, when the wafer is transferred from the transition chamber to the low-pressure chamber, the particle problem on the surface of the wafer has always been a difficult problem for the ISSG process and the PNA process, affecting the performance and yield of the manufactured semiconductor devices. Therefore, there is an urgent need for a wafer processing method to improve the above problems to ensure product performance and yield. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides a wafer processing method.

[0004] On the one hand, an embodiment of the present application provides a method for processing a wafer, the method comprising: A low-pressure process equipment is provided; the low-pressure process equipment comprises a low-pressure cavity and a transition chamber, the low-pressure cavity is arranged adjacent to the transition chamber, and a low-pressure cavity door is arranged between the low-pressure cavity and the transition chamber; inert gas is passed through the low-pressure cavity and the transition chamber; When the low-pressure cavity and the transition cabin are both in an idle state, and the corresponding idle time is greater than a preset idle time, the flow rate of the inert gas introduced into the low-pressure cavity is adjusted, and the flow rate of the inert gas introduced into the transition cabin is adjusted until a pressure balance state is reached between the low-pressure cavity and the transition cabin; Providing wafers to be processed, and transferring the wafers to be processed into the transition chamber; In the pressure balanced state, controlling the low-pressure chamber door to open, and controlling the wafer to be processed to be transferred from the transition chamber to the low-pressure chamber; The wafer to be processed is processed to obtain a processed wafer.

[0005] Furthermore, the above-mentioned adjusting the flow rate of the inert gas introduced into the low-pressure cavity and adjusting the flow rate of the inert gas introduced into the transition cabin until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin includes: Determining an initial flow rate of the inert gas in the low-pressure cavity and an initial flow rate of the inert gas in the transition chamber; Determining an initial pressure difference between an initial pressure of the low-pressure cavity and an initial pressure of the transition chamber according to a volume difference between the volume of the low-pressure cavity and the volume of the transition chamber, and an initial flow difference between an initial flow of the inert gas in the low-pressure cavity and an initial flow of the inert gas in the transition chamber; According to the initial pressure difference, the initial flow rate of the inert gas in the low-pressure cavity is adjusted, and the initial flow rate of the inert gas in the transition chamber is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber.

[0006] Further, the above-mentioned adjusting the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition chamber according to the initial pressure difference includes: determining a flow adjustment strategy according to the initial pressure difference; Based on the flow adjustment strategy, the initial flow of the inert gas entering the low-pressure cavity is adjusted, and the initial flow of the inert gas in the transition cabin is adjusted, so that there is an airflow difference between the low-pressure cavity and the transition cabin, thereby achieving the pressure balance state between the low-pressure cavity and the transition cabin.

[0007] Further, the above-mentioned determining the initial pressure difference between the initial pressure of the low-pressure cavity and the initial pressure of the transition cabin according to the volume difference between the volume of the low-pressure cavity and the volume of the transition cabin, and according to the initial flow difference between the initial flow of the inert gas in the low-pressure cavity and the initial flow of the inert gas in the transition cabin, comprises: When the volume of the low-pressure cavity is smaller than the volume of the transition chamber, and the initial flow rate of the inert gas introduced into the low-pressure cavity is equal to the initial flow rate of the inert gas introduced into the transition chamber, the initial pressure difference is determined to be that the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber; The flow adjustment strategy is determined according to the initial pressure difference, including: When the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber, determining that the flow adjustment strategy is to reduce the flow of the low-pressure cavity to a preset flow range; Based on the flow adjustment strategy, the initial flow rate of the inert gas introduced into the low-pressure cavity and the initial flow rate of the inert gas in the transition cabin are adjusted so that there is an airflow difference between the low-pressure cavity and the transition cabin, thereby achieving the pressure balance state between the low-pressure cavity and the transition cabin, including: The initial flow rate of the inert gas introduced into the low-pressure cavity is reduced to a preset flow rate range so that there is an airflow difference between the low-pressure cavity and the transition chamber, thereby achieving the pressure balance state between the low-pressure cavity and the transition chamber.

[0008] Furthermore, after the pressure between the low-pressure cavity and the transition cabin reaches a pressure equilibrium state, the method further comprises: Providing a test wafer, placing the test wafer in the transition chamber, controlling the low-pressure chamber door to open, and controlling the test wafer to be transferred from the transition chamber to the low-pressure chamber; Processing the test wafer to obtain a processed test wafer; Testing the processed test wafer to obtain a test result; Based on the test results, verify whether a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0009] Furthermore, the test results include a linear particle distribution diagram and the number of linear particles. Based on the test results, verifying whether a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber includes: Based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer, verify whether a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber; The above-mentioned verification of whether the pressure balance state is reached between the low-pressure cavity and the transition chamber based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer includes: When the linear particle distribution graph is inconsistent with any linear particle distribution graph in the historical linear particle distribution graph within a preset historical time period, and the number of linear particles is less than the linear particle control line, it is determined that the pressure equilibrium state is reached; When the linear particle distribution diagram is consistent with any linear particle distribution diagram in the historical linear particle distribution diagram within the preset historical time period, Figure 1 When the number of linear particles is greater than or equal to the linear particle control line, it is determined that the pressure equilibrium state has not been reached; the steps of determining the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition chamber are repeated, until the initial flow rate of the inert gas in the low-pressure cavity is adjusted according to the initial pressure difference, and the initial flow rate of the inert gas in the transition chamber is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber.

[0010] Furthermore, after controlling the low-pressure chamber door to open under the pressure balance state and controlling the wafer to be processed to be transferred from the transition chamber to the low-pressure chamber, the method further includes: The low-pressure chamber door is controlled to be closed, and the inert gas is stopped from being introduced into the low-pressure chamber.

[0011] Furthermore, the preset idle time is 1min-24h; The inert gas is at least one of nitrogen, argon, helium and krypton.

[0012] Further, the flow rate of the inert gas in the low-pressure chamber is in the range of 0 sccm-20000 sccm, and the flow rate of the inert gas in the transition chamber is in the range of 0 sccm-20000 sccm; The pressure range of the low-pressure cavity is 2Torr-10Torr, and the pressure range of the transition chamber is 2Torr-10Torr.

[0013] Furthermore, the number of the linear particle control lines is 20-50; The preset historical time period includes 3 months to 6 months.

[0014] On the other hand, an embodiment of the present application provides a wafer, which is processed using the above-mentioned wafer processing method.

[0015] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects: The wafer processing method provided in the embodiment of the present application is completed by using low-pressure process equipment; the low-pressure process equipment includes a low-pressure cavity and a transition chamber, the low-pressure cavity is arranged adjacent to the transition chamber, and a low-pressure cavity door is arranged between the low-pressure cavity and the transition chamber; inert gas is passed through the low-pressure cavity and the transition chamber; when the low-pressure cavity and the transition chamber are both in an idle state, and it is determined that the idle state time is greater than the preset idle time, before the wafer enters the low-pressure cavity, the inert gas flow of the low-pressure cavity and the transition chamber is controlled, so that the pressure balance state is reached between the low-pressure cavity and the transition chamber, which can avoid the particle problem caused by pressure imbalance when the wafer to be processed is transferred from the transition chamber to the low-pressure cavity. At this time, the wafer to be processed is processed according to the operation task to obtain a processed wafer. The above method can improve the quality and yield of the wafer, avoid the particle problem on the surface of the wafer in the low-pressure process, and thus improve the stability of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a schematic diagram of the principle of a reaction chamber of an in-situ steam oxidation process provided in an embodiment of the present application; Figure 2 It is a schematic diagram of the structure of a semiconductor device synthesized by an in-situ steam oxidation process provided in an embodiment of the present application; Figure 3 It is a schematic flow chart of a wafer processing method provided in an embodiment of the present application; Figure 4 It is a structural schematic diagram of a low-pressure process equipment provided in an embodiment of the present application; Figure 5 It is a structural schematic diagram of a low-pressure process equipment provided in an embodiment of the present application, in which an inert gas is passed; Figure 6 It is a flow chart of a flow adjustment method provided in an embodiment of the present application; Figure 7 It is a flow chart of a method for performing flow adjustment based on a flow adjustment strategy provided in an embodiment of the present application; Figure 8 It is a flow chart of a method for verifying a pressure balance state provided in an embodiment of the present application; Fig. 9 is a surface particle distribution diagram of a wafer obtained by processing when the pressure equilibrium state is not reached provided in an embodiment of the present application; Fig.10 This is a surface particle distribution diagram of a wafer obtained after reaching a pressure equilibrium state and then being processed according to an embodiment of the present application; Fig.11 (a) and Fig.11 (b) is a microscopic morphology of surface particles of a wafer obtained by processing without reaching a pressure equilibrium state provided in an embodiment of the present application; Fig.12 This is a comparison chart of the number of surface particles between a wafer processed without reaching a pressure equilibrium state and a wafer processed after reaching a pressure equilibrium state provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0019] In the wafer processing process, in order to repair the defects of the wafer or semiconductor devices and effectively improve the quality and electrical properties of semiconductor devices, the ISSG process (In Situ Steam Generation) or the PNA process (Partial Nitritation-Anammox) is usually used.

[0020] The ISSG process is an in-situ steam oxidation process. Figure 1 As shown, it mainly utilizes the strong oxidizing effect of atomic oxygen produced in the ISSG reaction, that is, hydrogen and oxygen react to generate water vapor and atomic oxygen, corresponding to Figure 1 H2+O2→H2O+O+OH+other substances in the reaction. Other substances represent side reactions and can be ignored. The above process can fully repair the Si / SiO2 interface, reduce the defects in the final oxide film, and effectively improve the quality and electrical properties of the film. Compared with the traditional wet oxidation process, the ISSG process has the following characteristics: 1. Closed-loop temperature control system, real-time temperature feedback and adjustment to ensure temperature stability.

[0021] 2. It can reduce the defects in the oxide film and improve the quality and electrical properties of SiO2.

[0022] ISSG process is widely used in key processes such as STI-OX (Shallow Trench Isolation with Oxide Fill) and GATE-OX (Gate Oxide, referring to the gate oxide layer in the transistor) in the semiconductor industry. The particle control of the machine plays a key role in chip performance. If there is surface PD (surface Particle Defect), it will lead to low-quality products. The semiconductor device synthesized using the ISSG process is shown in the figure below. Figure 2As shown in the figure, P-well stands for P-Well (PW for short), which is a structure used to form PMOS (P-channel Metal-Oxide-Semiconductor) transistors in semiconductor processes; the silicon oxide layer in shallow trench isolation, referred to as STI-OX, refers to the silicon oxide (Oxide) used in shallow trench isolation (STI) technology; N-well refers to N-Well (NW for short), which is a structure used to form NMOS (N-Metal-Oxide-Semiconductor) transistors in semiconductor processes; Source / Drain Rapid Thermal Annealing (S / D RTA for short) is a technology used in semiconductor processing technology to activate doping elements in semiconductor materials and restore the amorphous structure caused by ion implantation to a complete lattice structure; the second gate oxide layer, representing GATE2-OX (Dual GateOxide), refers to the gate oxide layer in CMOS (Complementary The second gate oxide layer in the dual-gate oxide process used in Metal-Oxide-Semiconductor (Complementary Metal-Oxide-Semiconductor) technology; SA-RTS refers to Self-Aligned Silicide technology; Polysilicon Re-oxidation (abbreviated as POLYRE-OX) is a processing step used in semiconductor technology to improve the characteristics of polysilicon (Polysilicon, referred to as Poly).

[0023] The semiconductor PNA process, or Post Nitridation Anneal, is an important process step for improving the performance of semiconductor devices. It is mainly used to repair lattice damage and form stable Si-N bonds, while repairing damage to the SiO2 / Si interface through secondary oxidation reactions at the interface in an oxidizing atmosphere. The PNA process plays a key role in semiconductor manufacturing, especially in the manufacture of Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFETs), where it helps improve device performance.

[0024] The ISSG process and the PNA process are carried out using a low-pressure chamber in a low-pressure process equipment. In the prior art, when the wafer is transferred from the transition chamber to the low-pressure chamber, the particle problem on the wafer surface has always been a difficult problem to solve for the ISSG process and the PNA process, affecting the performance and yield rate of the manufactured semiconductor devices. Therefore, a wafer processing method is urgently needed to improve the above problems and ensure product performance and yield rate.

[0025] Based on this, Figure 3 As shown, the embodiment of the present application improves a wafer processing method, comprising the following steps: S10: Provide a low-pressure process equipment; the low-pressure process equipment includes a low-pressure cavity and a transition chamber, the low-pressure cavity and the transition chamber are arranged adjacent to each other, and a low-pressure cavity door is arranged between the low-pressure cavity and the transition chamber; inert gas is passed through the low-pressure cavity and the transition chamber.

[0026] For example, Figure 4 As shown, the low-pressure process equipment includes a low-pressure cavity and a transition chamber. The low-pressure cavity is adjacent to the transition chamber, and a low-pressure cavity door is provided between the low-pressure cavity and the transition chamber. Inert gas is passed through the low-pressure cavity and the transition chamber.

[0027] The specific structure of the low-pressure process equipment includes an in-situ water vapor oxidation process chamber (ISSG chamber), a decoupled plasma nitridation chamber (DPN chamber), a post-nitridation annealing treatment chamber (PNA chamber), a transition chamber (Buffer), two vacuum transmission systems (LoadLock), a robot, a wafer aligner (aligner), a first wafer loading device, and a second wafer loading device; wherein the in-situ water vapor oxidation process chamber, the decoupled plasma nitridation chamber, and the post-nitridation annealing treatment chamber are respectively connected to the transition chamber; the wafer aligner (aligner) is respectively connected to the two vacuum transmission systems (LoadLock), the first wafer loading device, and the second wafer loading device.

[0028] Specifically, the PNA cavity and the ISSG cavity are both low-pressure cavities. The PNA cavity is suitable for the PNA process, and the ISSG cavity is suitable for the ISSG process. The following is a detailed introduction to the structure of the low-pressure process equipment: Two vacuum transfer systems (LoadLock), which can be named LLA and LLB, are equipment used to transfer wafers between different process steps. The LoadLock chamber acts as a transfer station between the atmosphere and the vacuum environment, allowing wafers to be loaded and unloaded without breaking the vacuum environment. This equipment usually contains one or more slots for storing wafers and needs to be frequently switched between the atmosphere and vacuum state.

[0029] The buffer is also called the intermediate buffer, which is used to provide a temporary storage and transition space between different process steps.

[0030] The DPN chamber refers to a device part in the Decoupled Plasma Nitridation technology used in the semiconductor manufacturing process. This technology is mainly used to nitride the gate oxide layer in semiconductor devices to improve its dielectric properties and reduce leakage current.

[0031] A wafer aligner is a device used to find and align the wafer during semiconductor manufacturing. Its main function is to use optical technology to determine the edge position of the wafer and rotate the wafer to a fixed angle to ensure that all wafers are in the same position and direction during subsequent processing. Figure 4 As shown, the aligner is equipped with a robot for wafer transfer.

[0032] The wafer loading device (Load port) provided in the embodiment of the present application includes a first wafer loading device and a second wafer loading device, which can be named LP1 and LP2, referring to the channel for wafers to enter and exit the device, and the location for storing wafer carriers (FOUP). FOUP (Front Opening Unified Pod) is a device used to transport and store semiconductor wafers in semiconductor manufacturing.

[0033] use Figure 4 The order of wafer processing by the provided low-voltage process equipment may be LP1 / LP2, aligner, LLA / LLB, buffer, ISSG / DPN / PNA.

[0034] S30: When the low-pressure cavity and the transition cabin are both in an idle state, and the corresponding idle times are greater than the preset idle times, the flow rate of the inert gas into the low-pressure cavity is adjusted, and the flow rate of the inert gas into the transition cabin is adjusted until a pressure balance state is reached between the low-pressure cavity and the transition cabin.

[0035] Exemplarily, this solution is for a low-pressure chamber process. Both the ISSG process and the PNA process are low-pressure processes. In the embodiments of the present application, the equipment that performs the low-pressure chamber process is referred to as a low-pressure process equipment.

[0036] When the operation task is started, that is, when the low-voltage process equipment is used to process the wafer, the operation state of the low-voltage process equipment and the corresponding operation time are determined.

[0037] When the low-pressure process equipment is in an idle state, that is, both the low-pressure chamber and the transition chamber are in an idle state, and the idle time corresponding to the idle state is greater than the preset idle time, inert gas will be introduced into the low-pressure chamber and the buffer area or no inert gas will be introduced into the idle state. When the inert gas is introduced, when the equipment starts wafer processing in the idle state, when the wafer is transferred from the transition chamber into the low-pressure chamber, due to the pressure imbalance between the transition chamber and the low-pressure chamber, it will cause a pressure difference, resulting in particles on the wafer surface.

[0038] Therefore, when it is determined that the low-pressure cavity and the transition cabin are both in an idle state, and the corresponding idle time is greater than the preset idle time, Figure 5 As shown, the flow rate of the inert gas introduced into the low-pressure cavity is adjusted, and the flow rate of the inert gas introduced into the transition cabin is adjusted until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0039] Optionally, the preset idle time is determined according to different processes.

[0040] The above-mentioned pressure balance state is a dynamic balance state. This dynamic balance means that by controlling the moment when the cavity door opens, the flow in and out of the low-pressure cavity reaches a balance point, thereby achieving stable control of the pressure between the low-pressure cavity and the transition cabin.

[0041] S50: providing wafers to be processed, and transferring the wafers to be processed to a transition chamber.

[0042] Exemplarily, after determining that a pressure balance state is reached between the low-pressure chamber and the transition chamber, wafers to be processed can be provided according to the target processing task, and transferred to the transition chamber through LP1 or LP2, aligner, LLA or LLB.

[0043] S70: Under the pressure balance state, control the low-pressure chamber door to open, and control the wafer to be processed to be transferred from the transition chamber to the low-pressure chamber.

[0044] Exemplarily, under the pressure balance state, the low-pressure chamber door is controlled to open, and the wafer to be processed is transferred from the transition chamber to the low-pressure chamber.

[0045] S90: Process the wafer to be processed to obtain a processed wafer.

[0046] Exemplarily, according to the target processing task, the wafer to be processed is processed to obtain a processed wafer. The target processing task here refers to the target process in the low-pressure chamber.

[0047] It should be noted that it is necessary to ensure that the processing of each wafer is carried out under a pressure balance state.

[0048] The embodiment of the present application provides a wafer processing method. When the low-pressure chamber and the transition chamber are both in an idle state, and it is determined that the idle state time is greater than the preset idle time, before the wafer enters the low-pressure chamber, the inert gas flow rate of the low-pressure chamber and the transition chamber is controlled to achieve a pressure balance between the low-pressure chamber and the transition chamber, which can avoid the particle problem caused by pressure imbalance when the wafer to be processed is transferred from the transition chamber to the low-pressure chamber. At this time, the wafer to be processed is processed according to the operation task to obtain a processed wafer. The above method can improve the quality and yield of the wafer, avoid the particle problem on the wafer surface in the low-pressure process, and thus improve the stability of the process.

[0049] As an optional implementation, the preset idle time is 1min-24h; The inert gas is at least one of nitrogen, argon, helium and krypton.

[0050] Exemplarily, the preset idle time is determined according to different processes, so it can be set to 1 min-24 h. In order to ensure the best wafer processing state, 1 min is preferred.

[0051] The role of the inert gas is to protect the atmosphere, prevent oxidation and pollution, etc. It can be at least one of nitrogen, argon, helium and krypton. For cost considerations, nitrogen is preferred.

[0052] As an optional implementation, after the above step S70, the above method further includes: S80: Control the low-pressure chamber door to close, and stop introducing inert gas into the low-pressure chamber.

[0053] Exemplarily, after the wafer is transferred to the low-pressure chamber, the slit door of the low-pressure chamber is controlled to be closed, and the inert gas is stopped from being introduced into the low-pressure chamber, and the gas set in the target processing task recipe is introduced.

[0054] As an optional implementation, Figure 6 As shown, in the above step S30, the flow rate of the inert gas introduced into the low-pressure cavity is adjusted, and the flow rate of the inert gas introduced into the transition cabin is adjusted until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin, including: S31: Determine an initial flow rate of the inert gas in the low-pressure cavity and an initial flow rate of the inert gas in the transition chamber.

[0055] S32: Determine the initial pressure difference between the initial pressure of the low-pressure cavity and the initial pressure of the transition chamber based on the volume difference between the volume of the low-pressure cavity and the volume of the transition chamber, and based on the initial flow difference between the initial flow of the inert gas in the low-pressure cavity and the initial flow of the inert gas in the transition chamber.

[0056] S33: According to the initial pressure difference, the initial flow rate of the inert gas in the low-pressure cavity is adjusted, and the initial flow rate of the inert gas in the transition cabin is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0057] Exemplarily, since the pressure imbalance between the low-pressure cavity and the transition chamber (buffer) is caused by the difference in the structural size of the low-pressure cavity and the buffer, and the difference in the flow rate of the inert gas in the low-pressure cavity and the buffer in the idle state, the steps for adjusting the pressure balance between the low-pressure cavity and the buffer are as follows: S31: Determine an initial flow rate of the inert gas in the low-pressure cavity and an initial flow rate of the inert gas in the transition chamber.

[0058] S32: First, determine the volume of the low-pressure cavity and the volume of the transition chamber, and then determine the volume difference between the volume of the low-pressure cavity and the volume of the transition chamber, and determine the initial flow difference between the initial flow of the inert gas in the low-pressure cavity and the initial flow of the inert gas in the transition chamber, so as to determine the initial pressure difference between the initial pressure of the low-pressure cavity and the initial pressure of the transition chamber based on the volume difference and the initial flow difference.

[0059] Optionally, the calculation method of the pressure difference may be based on the ideal gas state equation or the Bernoulli equation.

[0060] Specifically, the volume difference will affect the speed and magnitude of the pressure change in the cavity. The initial flow difference will directly affect the rate of change of the pressure in the cavity.

[0061] S33: According to the initial pressure difference, the initial flow rate of the inert gas in the low-pressure cavity is adjusted, and the initial flow rate of the inert gas in the transition cabin is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0062] The embodiment of the present application determines the initial pressure difference between the initial pressure of the low-pressure chamber and the initial pressure of the transition chamber according to the volume difference between the volume of the low-pressure chamber and the volume of the transition chamber, and according to the initial flow difference between the initial flow of the inert gas in the low-pressure chamber and the initial flow of the inert gas in the transition chamber, so that the initial flow of the inert gas in the low-pressure chamber can be adjusted according to the initial pressure difference, and the initial flow of the inert gas in the transition chamber can be adjusted until a pressure equilibrium state is reached between the low-pressure chamber and the transition chamber, thereby avoiding particle problems caused by pressure imbalance at the moment when the wafer to be processed is transferred from the transition chamber to the low-pressure chamber, improving the quality and yield of the wafer, avoiding the particle problem on the wafer surface in the low-pressure process, and thus improving the stability of the process.

[0063] As an optional implementation, Figure 7 As shown, in the above step S33, the above adjustment of the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition chamber according to the initial pressure difference includes: S331: Determine a flow adjustment strategy based on the initial pressure difference.

[0064] Exemplarily, a flow adjustment strategy may be determined based on the initial pressure difference, where the flow adjustment strategy refers to the adjustment direction of the initial gas flow in the low-pressure cavity and the adjustment direction of the initial flow of the inert gas in the transition chamber.

[0065] Optionally, the adjustment direction can be a step-by-step adjustment, for example, based on the initial pressure difference, determine the predicted flow range at the equilibrium state corresponding to the flow adjustment strategy, and then gradually adjust the flow, increasing or decreasing a fixed value each time until the preset flow range is reached.

[0066] S332: Based on the flow adjustment strategy, the initial flow of the inert gas introduced into the low-pressure cavity is adjusted, and the initial flow of the inert gas in the transition chamber is adjusted, so that there is an airflow difference between the low-pressure cavity and the transition chamber, thereby achieving a pressure balance state between the low-pressure cavity and the transition chamber.

[0067] Exemplarily, according to the determined flow adjustment strategy, the initial flow rate of the inert gas introduced into the low-pressure cavity is adjusted, and the initial flow rate of the inert gas in the transition chamber is adjusted.

[0068] As an optional embodiment, the above-mentioned determining the initial pressure difference between the initial pressure of the low-pressure cavity and the initial pressure of the transition cabin according to the volume difference between the volume of the low-pressure cavity and the volume of the transition cabin, and according to the initial flow difference between the initial flow of the inert gas in the low-pressure cavity and the initial flow of the inert gas in the transition cabin, includes: When the volume of the low-pressure cavity is smaller than the volume of the transition tank, and the initial flow rate of the inert gas entering the low-pressure cavity is equal to the initial flow rate of the inert gas entering the transition tank, the initial pressure difference is determined to be that the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition tank.

[0069] Optionally, the above process is based on the same temperature. When affected by temperature or other factors, the initial pressure difference may also be different, and it is determined based on actual conditions.

[0070] The flow adjustment strategy is determined based on the initial pressure difference, including: When the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber, the flow adjustment strategy is determined to reduce the flow of the low-pressure cavity to a preset flow range.

[0071] The above-mentioned flow adjustment strategy is based on adjusting the initial flow of the inert gas introduced into the low-pressure cavity and the initial flow of the inert gas in the transition cabin, so that there is an airflow difference between the low-pressure cavity and the transition cabin, so that the pressure balance state is achieved between the low-pressure cavity and the transition cabin, including: The initial flow rate of the inert gas introduced into the low-pressure cavity is reduced to a preset flow range so that there is an airflow difference between the low-pressure cavity and the transition chamber, thereby achieving a pressure balance state between the low-pressure cavity and the transition chamber.

[0072] Exemplarily, the above determination method is described with a specific embodiment: When the volume of the low-pressure chamber is smaller than the volume of the transition chamber, the initial flow rate of the low-pressure chamber is 2000 sccm, and the initial flow rate of the buffer is also 2000 sccm. At this time, the pressure of the low-pressure chamber is greater than the buffer pressure.

[0073] When it is determined that the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber, the flow adjustment strategy is determined to reduce the flow of the low-pressure cavity to a preset flow range, specifically, it can be 1800sccm~1500sccm.

[0074] The initial flow rate of the inert gas introduced into the low-pressure chamber is reduced from 2000sccm to a preset flow rate range of 1800sccm~1500sccm, so that the air flow difference between the low-pressure chamber and the transition chamber can cover the structural and size differences between the low-pressure chamber and the buffer, thereby achieving a pressure balance between the low-pressure chamber and the transition chamber.

[0075] The embodiment of the present application determines the flow adjustment strategy according to the pressure difference, so that it can be adjusted according to the flow strategy until the pressure balance state is reached between the low-pressure chamber and the transition chamber, thereby avoiding the particle problem caused by pressure imbalance at the moment when the wafer to be processed is transferred from the transition chamber to the low-pressure chamber. The quality and yield of the wafer can be improved, and the particle problem on the wafer surface in the low-pressure process can be avoided, thereby improving the stability of the process.

[0076] As an optional implementation, the flow rate range of the inert gas in the low-pressure chamber is 0 sccm-20000 sccm, and the flow rate range of the inert gas in the transition chamber is 0 sccm-20000 sccm; The pressure range of the low-pressure cavity is 2Torr-10Torr, and the pressure range of the transition chamber is 2Torr-10Torr.

[0077] It should be noted that the above flow range and pressure range both include an initial range and a final range, that is, it is sufficient to ensure that the low-pressure cavity and the cavity of the transition chamber are within the above range.

[0078] As an optional implementation, after reaching a pressure equilibrium state, such as Figure 8 As shown, the present application also provides a method for verifying the pressure balance state, that is, after the above step S30, the above method further includes: S111: providing a test wafer, placing the test wafer in the transition chamber, controlling the low-pressure chamber door to open, and controlling the test wafer to be transferred from the transition chamber to the low-pressure chamber; S113: Processing the test wafer to obtain a processed test wafer; S115: Testing the processed test wafer to obtain a test result; S117: Based on the test results, verify whether the pressure balance is achieved between the low-pressure cavity and the transition chamber.

[0079] Exemplarily, the test wafer is processed according to the normal wafer processing flow to obtain a processed test wafer. The above processing needs to ensure that it is completely consistent with the normal wafer processing process.

[0080] The processed test wafer is tested to obtain the test results, and the test results are analyzed to verify whether the pressure balance state is reached between the low-pressure cavity and the transition chamber.

[0081] As an optional implementation, the test results include a linear particle distribution diagram and the number of linear particles. Based on the test results, verifying whether a pressure balance state is achieved between the low-pressure cavity and the transition cabin includes: Based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer, it is verified whether the pressure balance state is achieved between the low-pressure cavity and the transition chamber.

[0082] Exemplarily, the test results include a special map of linear particles and the number of linear particles. Here, the analysis focuses on the reason why the linear particles are caused by the pressure not reaching a balanced state, and the particle defects are mainly linear particles. However, it can also be a particle distribution map and the number of particles, and this application does not limit this.

[0083] Based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer, verify whether the pressure balance between the low-pressure chamber and the transition chamber is achieved, including: When the linear particle distribution graph is inconsistent with any of the historical linear particle distribution graphs within a preset historical time period, and the number of linear particles is less than the linear particle control line, it is determined that the pressure equilibrium state is reached; When the linear particle distribution graph is consistent with any linear particle distribution graph in the historical linear particle distribution graph within the preset historical time period, Figure 1 When the number of linear particles is greater than or equal to the linear particle control line, it is determined that the pressure equilibrium state has not been reached; the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition cabin are repeatedly determined, and the initial flow rate of the inert gas in the low-pressure cavity is adjusted according to the initial pressure difference, and the initial flow rate of the inert gas in the transition cabin is adjusted, until the pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0084] Exemplarily, the historical linear particle distribution map within a preset historical time period refers to the linear particle distribution map within a past period of time; the linear particle control line refers to the maximum number of linear particles allowed to exist on the surface of the wafer.

[0085] In an optional embodiment, the number of linear particle control lines is 20-50; the preset historical time period includes 3 months to 6 months.

[0086] The preset historical time period includes 3 months to 6 months. The setting basis is based on existing experience. After each pressure balance adjustment, it can be ensured that the machine will not generate wireless particles for 3 months to 6 months when it is not idle.

[0087] The verification process and judgment conditions are as follows: When the linear particle distribution graph is inconsistent with any of the historical linear particle distribution graphs within a preset historical time period, and the number of linear particles is less than the linear particle control line, it is determined that the pressure equilibrium state is reached; When the linear particle distribution graph is consistent with any linear particle distribution graph in the historical linear particle distribution graph within the preset historical time period, Figure 1 When the number of linear particles is greater than or equal to the linear particle control line, it is determined that the pressure equilibrium state has not been reached, that is, the linear particle distribution diagram and the number of linear particles must meet the requirements to determine that the pressure equilibrium state is reached, otherwise, the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition cabin are repeatedly determined, and the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition cabin are adjusted according to the initial pressure difference, until the pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

[0088] It should be noted that the above verification method can be used not only after each pressure balance adjustment operation, but also for daily inspection. Before daily operation tasks, the above method can be used for verification to ensure the product yield in the normal wafer processing process. The cycle can be every 24 hours.

[0089] The application embodiment can verify whether the pressure balance state is reached by judging the linear particle distribution diagram and the number of linear particles, thereby effectively ensuring the effectiveness of the pressure balance state adjustment, thereby avoiding the particle problem caused by pressure imbalance at the moment when the wafer to be processed is transferred from the transition cabin to the low-pressure chamber, improving the quality and yield of the wafer, avoiding the particle problem on the wafer surface in the low-pressure process, and thus improving the stability of the process.

[0090] In order to ensure that the wafer is transferred from the transition chamber to the low-pressure chamber in a pressure-balanced state, a locking and alarm function can also be set in the control program of the low-pressure chamber. The locking and alarm functions can be turned on and off manually. When the locking and alarm functions are turned on, when the wafer is transferred from the transition chamber to the low-pressure chamber in a pressure-balanced state, the wafer can be transferred normally; when the wafer is transferred from the transition chamber to the low-pressure chamber in a non-pressure-balanced state, the chamber door can be controlled to delay opening or not opening, and an alarm can be sounded to remind the user. The alarm method can be in the form of whistle, human-computer interaction module error, etc. The delayed opening or not opening can be set by the user, and the delayed opening time is also set by the user.

[0091] The present application also provides examples and comparative examples to illustrate the effects of the above scheme: Comparative Example 1: Steps S10, S50, S70, and S90 are performed. The difference from Example 1 is that the flow rate is not adjusted, that is, the pressure state between the low-pressure chamber and the transition chamber is not controlled. After the processed wafer is obtained, it is tested, and its particle distribution diagram is as follows: Fig. 9 And repeat the above process several times.

[0092] Example 1: After the low-pressure process equipment performs comparative example 1, steps S10-S90 are performed to obtain the processed wafer and then test it. The particle distribution diagram is as follows: Fig.10 As shown; repeat the process of steps S10-S90 several times and perform a particle number test.

[0093] Fig.11 (a) and Fig.11 (b) is a SEM image of particles on the wafer surface of Comparative Example 1. Fig.11 (a) and Fig.11 As can be seen from (b) in the figure, the particles are in a linear or strip shape, which are collectively referred to as strips in the embodiments of the present application.

[0094] Fig. 9 and Fig.10 By comparison, it is found that after executing step S30, the number of linear particles on the wafer surface is almost zero. Fig.12 is a comparison chart of the number of surface particles of a wafer processed without reaching a pressure equilibrium state and a wafer processed after reaching a pressure equilibrium state provided in an embodiment of the present application, Fig.12 In the figure, the vertical axis is the number of particles, the horizontal axis represents the order of wafer testing, and each horizontal axis represents a wafer. Fig.12 It can be seen that executing step S30 during the wafer processing can effectively reduce the number of particles on the wafer surface. Fig.12 The specification line and control line are used to monitor and control the production process to ensure that the product quality meets the predetermined standards, and the control line corresponds to the above-mentioned linear particle control line. Fig.12 The specification lines and control lines are examples only.

[0095] To summarize, the present invention understands the technical analysis of the generation of particles on the wafer surface, and after finding the cause of the defect, changes the process flow and parameters to solve the problem of surface particles on the wafer in the low-pressure process. After using this method, the quality and yield of the wafer can be improved, and the problem of surface particles on the wafer in the low-pressure process can be avoided, thereby improving the stability of the process.

[0096] The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.

Claims

1. A wafer processing method, characterized in that: The method comprises: A low-pressure process equipment is provided; the low-pressure process equipment comprises a low-pressure cavity and a transition chamber, the low-pressure cavity is arranged adjacent to the transition chamber, and a low-pressure cavity door is arranged between the low-pressure cavity and the transition chamber; inert gas is passed through the low-pressure cavity and the transition chamber; When the low-pressure cavity and the transition cabin are both in an idle state, and the corresponding idle time is greater than a preset idle time, the flow rate of the inert gas introduced into the low-pressure cavity is adjusted, and the flow rate of the inert gas introduced into the transition cabin is adjusted until a pressure balance state is reached between the low-pressure cavity and the transition cabin; Providing wafers to be processed, and transferring the wafers to be processed into the transition chamber; In the pressure balanced state, controlling the low-pressure chamber door to open, and controlling the wafer to be processed to be transferred from the transition chamber to the low-pressure chamber; The wafer to be processed is processed to obtain a processed wafer.

2. The wafer processing method according to claim 1, characterized in that: The step of adjusting the flow rate of the inert gas introduced into the low-pressure cavity and the flow rate of the inert gas introduced into the transition cabin until a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin comprises: Determining an initial flow rate of the inert gas in the low-pressure cavity and an initial flow rate of the inert gas in the transition chamber; Determining an initial pressure difference between an initial pressure of the low-pressure cavity and an initial pressure of the transition chamber according to a volume difference between the volume of the low-pressure cavity and the volume of the transition chamber, and an initial flow difference between an initial flow of the inert gas in the low-pressure cavity and an initial flow of the inert gas in the transition chamber; According to the initial pressure difference, the initial flow rate of the inert gas in the low-pressure cavity is adjusted, and the initial flow rate of the inert gas in the transition chamber is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber.

3. The wafer processing method according to claim 2, characterized in that: The adjusting the initial flow rate of the inert gas in the low-pressure cavity and the adjusting the initial flow rate of the inert gas in the transition chamber according to the initial pressure difference comprises: determining a flow adjustment strategy according to the initial pressure difference; Based on the flow adjustment strategy, the initial flow of the inert gas entering the low-pressure cavity is adjusted, and the initial flow of the inert gas in the transition cabin is adjusted, so that there is an airflow difference between the low-pressure cavity and the transition cabin, thereby achieving the pressure balance state between the low-pressure cavity and the transition cabin.

4. The wafer processing method according to claim 3, characterized in that: The determining of the initial pressure difference between the initial pressure of the low-pressure cavity and the initial pressure of the transition cabin according to the volume difference between the volume of the low-pressure cavity and the volume of the transition cabin, and the initial flow difference between the initial flow of the inert gas in the low-pressure cavity and the initial flow of the inert gas in the transition cabin, comprises: When the volume of the low-pressure cavity is smaller than the volume of the transition chamber, and the initial flow rate of the inert gas introduced into the low-pressure cavity is equal to the initial flow rate of the inert gas introduced into the transition chamber, the initial pressure difference is determined to be that the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber; Determining a flow adjustment strategy according to the initial pressure difference includes: When the initial pressure of the low-pressure cavity is greater than the initial pressure of the transition chamber, determining that the flow adjustment strategy is to reduce the flow of the low-pressure cavity to a preset flow range; The method of adjusting the initial flow rate of the inert gas introduced into the low-pressure cavity and the initial flow rate of the inert gas in the transition chamber based on the flow rate adjustment strategy so that there is an airflow difference between the low-pressure cavity and the transition chamber, thereby achieving the pressure balance state between the low-pressure cavity and the transition chamber, includes: The initial flow rate of the inert gas introduced into the low-pressure cavity is reduced to a preset flow rate range so that there is an airflow difference between the low-pressure cavity and the transition chamber, thereby achieving the pressure balance state between the low-pressure cavity and the transition chamber.

5. The wafer processing method according to claim 2, characterized in that: After the pressure balance between the low-pressure cavity and the transition cabin is reached, the method further comprises: Providing a test wafer, placing the test wafer in the transition chamber, controlling the low-pressure chamber door to open, and controlling the test wafer to be transferred from the transition chamber to the low-pressure chamber; Processing the test wafer to obtain a processed test wafer; testing the processed test wafer to obtain a test result; Based on the test results, verify whether a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin.

6. The wafer processing method according to claim 5, characterized in that: The test result includes a linear particle distribution diagram and the number of linear particles. Based on the test result, verifying whether a pressure equilibrium state is reached between the low-pressure cavity and the transition cabin includes: Based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer, determining whether a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber; The determining whether a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber based on the linear particle distribution diagram and the number of linear particles on the surface of the processed test wafer comprises: When the linear particle distribution graph is inconsistent with any linear particle distribution graph in the historical linear particle distribution graph within a preset historical time period, and the number of linear particles is less than the linear particle control line, it is determined that the pressure equilibrium state is reached; When the linear particle distribution graph is consistent with any linear particle distribution graph in the historical linear particle distribution graph within the preset historical time period, and / or the number of linear particles is greater than or equal to the linear particle control line, it is determined that the pressure equilibrium state has not been reached; repeat the steps of determining the initial flow rate of the inert gas in the low-pressure cavity and the initial flow rate of the inert gas in the transition chamber, until the initial flow rate of the inert gas in the low-pressure cavity is adjusted according to the initial pressure difference, and the initial flow rate of the inert gas in the transition chamber is adjusted, until a pressure equilibrium state is reached between the low-pressure cavity and the transition chamber.

7. The wafer processing method according to claim 1, characterized in that: After controlling the low-pressure chamber door to open under the pressure balance state and controlling the wafer to be processed to be transferred from the transition chamber to the low-pressure chamber, the method further includes: The low-pressure chamber door is controlled to be closed, and the inert gas is stopped from being introduced into the low-pressure chamber.

8. The wafer processing method according to claim 1, characterized in that: The preset idle time is 1min-24h; The inert gas is at least one of nitrogen, argon, helium and krypton.

9. The wafer processing method according to claim 4, characterized in that: The flow rate of the inert gas in the low-pressure chamber is in the range of 0 sccm-20000 sccm, and the flow rate of the inert gas in the transition chamber is in the range of 0 sccm-20000 sccm; The pressure range of the low-pressure cavity is 2Torr-10Torr, and the pressure range of the transition cabin is 2Torr-10Torr.

10. The wafer processing method according to claim 6, characterized in that: The number of the linear particle control lines is 20-50; The preset historical time period includes 3 months to 6 months.

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