A liquid replenishing method for wafer epitaxial layer processing

Abstract

A method for replenishing liquid for epitaxial layer processing of wafers, comprising: a growth end, which is provided with a growth furnace; an auxiliary end, which is provided with a main chamber, a secondary chamber, and an auxiliary chamber; the steps include: during the processing between two adjacent wafers, when the epitaxial layer processing of the previous wafer is completed, the growth end continuously sends a replenishing liquid signal to the main chamber, and the auxiliary end determines whether the main chamber needs replenishing liquid; if replenishing liquid is not needed, wait for the epitaxial layer processing of the next wafer; if replenishing liquid is needed, add solution to the main chamber; wherein, when replenishing liquid is not needed, the growth furnace and the main chamber are kept connected, and the main chamber and the secondary chamber are kept connected. This method can ensure that the pressure fluctuation between epitaxial wafer furnaces is controlled from the existing ±1.5psi to ±0.2psi, and the uniformity between epitaxial wafer furnaces is optimized from the original >1.0% to <0.5%, converges the fluctuation between epitaxial wafer furnaces, improves the film quality of the epitaxial layer, has a significant film forming effect between furnaces, has good repeatability between furnaces, and improves production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor device production, and in particular relates to a liquid replenishing method for wafer epitaxial layer processing. Background Art

[0002] Epitaxial process refers to the process of growing a single crystal thin film on a single crystal substrate according to the crystal orientation of the substrate. In a broad sense, epitaxy is also a CVD (chemical vapor deposition) process. The newly formed single crystal layer is called an epitaxial layer, and the substrate with the epitaxial layer is called an epitaxial wafer. The process is that the growth gas enters the growth chamber, and through high-temperature thermal decomposition and reduction reaction, a layer of silicon single crystal thin film is deposited and grown on the surface of the substrate. Because of the attraction between atoms, the generated silicon single crystal thin film is attached to the substrate. Among them, the growth gas is a gas formed by hydrogen (H2) carrying TCS (silicon trichloride SiHCl3 solution).

[0003] As the main material of semiconductor devices, silicon epitaxial materials support the development of the contemporary microelectronics industry. As IC manufacturing develops towards smaller feature line widths and thinner epitaxial layers, integrated circuit devices have increasing requirements for the quality of epitaxial wafers, and also put forward higher requirements for the functions and epitaxial performance of epitaxial systems, such as the uniformity control of epitaxial layer thickness. More and more epitaxial processes require the use of monolithic silicon epitaxial processing equipment.

[0004] In existing epitaxial processing equipment, the flow rate and pressure of hydrogen carrying TCS are often unstable due to unreasonable liquid replenishment methods, resulting in large pressure fluctuations and non-repeatability in the cavity storing the growth gas before the epitaxial layer of the wafer grows. This ultimately causes the pressure to change when hydrogen carrying TCS enters the growth furnace to deposit the long film, and the growth rate of the epitaxial layer also changes, resulting in large differences in the thickness of the epitaxial layer of the wafers between furnaces after the growth furnace deposits the long film, and a low yield rate. Summary of the invention

[0005] The present invention provides a liquid replenishing method for wafer epitaxial layer processing, which solves the technical problems in the prior art that the overall yield of the epitaxial wafer is low and the film thickness deviation between furnaces is too large.

[0006] In order to solve at least one of the above technical problems, the technical solution adopted by the present invention is:

[0007] A liquid replenishment method for wafer epitaxial layer processing, comprising: a growth end, used for wafer epitaxial layer growth, which is configured with a growth furnace; an auxiliary end, used for providing growth gas to the growth end, which is configured with a main chamber for storing growth gas, a secondary chamber for providing hydrogen to the main chamber, and an auxiliary chamber for providing TCS to the main chamber; the steps include:

[0008] During the processing between two adjacent wafers, when the epitaxial layer processing of the previous wafer is completed, the growth end continuously sends a liquid replenishment signal to the main chamber, and the auxiliary end determines whether the main chamber needs liquid replenishment;

[0009] If no refilling is needed, wait for the next wafer epitaxial layer processing;

[0010] If rehydration is necessary, add solution to the main chamber;

[0011] When liquid replenishment is not required, the growth furnace and the main chamber are kept in communication, and the main chamber and the sub-chamber are kept in communication.

[0012] Furthermore, when the liquid level of TCS in the main chamber is at a high level, no liquid replenishment is required;

[0013] When the liquid level of TCS in the main chamber is at a low level, it needs to be replenished.

[0014] Further, when fluid replacement is needed, it includes:

[0015] After the main chamber receives the liquid replenishment signal ON, it delays 0.1-0.3s, connects the auxiliary chamber with the main chamber to start liquid replenishment, and stops bubbling in the main chamber;

[0016] During fluid replenishment, operations are performed alternately according to the preset fluid replenishment signal and pressure relief signal until the TCS liquid level in the main chamber reaches the high liquid level.

[0017] Furthermore, during fluid infusion, the alternating fluid infusion time is the same as the pressure relief time.

[0018] Furthermore, the alternating fluid infusion time and pressure relief time are both 5 s.

[0019] Furthermore, the controller that provides the liquid replenishment signal to the main chamber is connected to the secondary chamber and the auxiliary chamber through electrical signals.

[0020] Furthermore, the controller that provides the liquid replenishment signal to the main chamber is connected to the air valves on all the pipelines in the auxiliary end through electrical signals.

[0021] Furthermore, the controller that provides the growth signal to the growth furnace is connected to the controller that provides the liquid replenishment signal to the main chamber through an electrical signal.

[0022] Furthermore, when the main chamber receives a signal to close the liquid replenishment or the liquid level of TCS in the main chamber reaches a high liquid level, the liquid replenishment is stopped, and the growth furnace is controlled to be connected with the main chamber, and the main chamber is controlled to be connected with the secondary chamber.

[0023] Furthermore, after the main chamber receives the refilling signal OFF, it delays 0.1-0.3s, controls the main chamber to start bubbling, and stops refilling;

[0024] Until the epitaxial layer processing of the next wafer begins.

[0025] A liquid replenishing method for wafer epitaxial layer processing designed by the present invention can ensure that the pressure fluctuation between epitaxial wafer furnaces is controlled from the existing ±1.5psi to ±0.2psi, and the uniformity between epitaxial wafer furnaces is optimized from the original >1.0% to <0.5%, thereby converging the fluctuation between epitaxial wafer furnaces, improving the film forming quality of the epitaxial layer, achieving significant film forming effect between furnaces, good repeatability between furnaces, improving production efficiency, and saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of a fluid replenishment method according to an embodiment of the present invention;

[0027] Figure 2 is a wireframe diagram of a fluid infusion system according to an embodiment of the present invention;

[0028] Figure 3 is a flow chart of a fluid replenishment signal control according to an embodiment of the present invention;

[0029] Figure 4 is a schematic diagram of the fluid replenishment logic of an embodiment of the present invention;

[0030] Figure 5 It is a schematic diagram of the change of epitaxial layer film thickness data obtained by using the liquid replenishment method of the present application;

[0031] Figure 6 It is a schematic diagram of the change of TCS hydrogen pressure when the rehydration method of the present application is used for rehydration;

[0032] Figure 7 It is a schematic diagram of the change of epitaxial layer film thickness data obtained by using the existing liquid replenishment method;

[0033] Figure 8 It is a schematic diagram of the change of TCS hydrogen pressure when the existing rehydration method is used for rehydration.

[0034] In the figure:

[0035] 10. Growth end 11. Growth furnace 12. Controller 1 DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] This embodiment provides a method for replenishing liquid in wafer epitaxial layer processing, the process is as follows: Figure 1 As shown, the steps include:

[0038] S1. Growth control of the epitaxial layer of the previous wafer.

[0039] The fluid replenishment method of the present application is used for Figure 2 The fluid replacement system shown comprises:

[0040] The growth end 10 is used for growing epitaxial layers of wafers, and is provided with a growth furnace 11 and a controller 12 for controlling the growth furnace 11 and sending growth instruction signals to the growth furnace 11.

[0041] The auxiliary end 20 is used to provide growth gas to the growth end 10, and is configured with a main chamber 21 for storing growth gas, a sub-chamber 22 for providing hydrogen to the main chamber 21, an auxiliary chamber 23 for providing TCS to the main chamber 21, and a controller 24 for controlling the auxiliary end 20 and sending liquid replenishment command signals to the main chamber 21, the sub-chamber 22 and the auxiliary chamber 23.

[0042] Among them, the fluid replenishment signal control is as follows Figure 3 As shown, the controller 12 is connected to the growth furnace 11 through an electrical signal, and controls the opening or closing of the growth furnace 11 through a pneumatic valve (the pneumatic valve is omitted in the figure); at the same time, when the epitaxial layer processing is not performed, the controller 12 continuously transmits a liquid replenishment signal to the auxiliary end 20 through an electrical signal. The controller 2 24 is respectively connected to the main chamber 21, the secondary chamber 22 and the auxiliary chamber 23 through electrical signals, and controls each valve through electrical signals to control the connection between the main chamber 21 and the growth furnace 11, the connection between the main chamber 21 and the secondary chamber 22, the connection between the main chamber 21 and the auxiliary chamber 23, and the pressure relief of the main chamber 21.

[0043] In detail, an air intake valve PV3 and a pressure relief valve PV6 are provided on the pipeline connecting the main chamber 21 with the growth furnace 11, an air intake valve PV4 and a pressure relief valve PV7 are provided on the pipeline connecting the main chamber 21 with the secondary chamber 22, and an air intake valve PV2 and a pressure relief valve PV5 are provided on the pipeline connecting the main chamber 21 with the auxiliary chamber 23; all the pressure relief valves are connected to the pressure relief pipeline of the main chamber 21, and a total pressure relief valve PV8 is also provided at the output end of the pressure relief pipeline.

[0044] At the same time, in order to monitor the pressure of the growth gas entering the growth furnace 11, a pressure gauge PT0 is provided on the pipe connecting the main chamber 21 and the growth furnace 11; in order to monitor the pressure inside the main chamber 21 during the liquid replenishment process, a pressure gauge PT1 is provided on the pipe connecting the main chamber 21; in order to monitor the pressure control of the pressure relief process of the main chamber 21, a pressure gauge PT2 is provided at the output end of the pressure relief pipe.

[0045] When any wafer is undergoing epitaxial layer growth in the growth furnace 11, the controller 12 directly transmits a growth signal to the growth furnace 11 through an electrical signal, and controls the pneumatic valve that starts the growth furnace 11 to open directly; at the same time, after the controller 24 receives the growth signal sent by the controller 12, the controller 24 directly controls PV3 and PV4 to open, ensuring that the growth furnace 11 and the main chamber 21 are connected, so that hydrogen carries TCS into the cavity of the growth furnace 11, and the secondary chamber 22 is connected to the main chamber 21 and continuously introduces hydrogen into the main chamber 21, so that the mixed production gas in the main chamber 21 is continuously and stably input into the growth furnace 11.

[0046] Since the growth gas is hydrogen and TCS, it enters the growth furnace 11 and undergoes high-temperature thermal decomposition and reduction reaction to deposit and grow a silicon single crystal thin film layer, i.e., an epitaxial layer, on the substrate surface of the wafer. Therefore, in the main chamber 21 in the auxiliary end 20, a growth gas mixed with hydrogen and TCS that meets the standard saturated vapor pressure requirements must be prepared. It is necessary to ensure that the pressure change at the gas-liquid interface in the main chamber 21 is always stable, so as to ensure that the pressure and flow rate of the growth gas entering the growth furnace 11 are consistent.

[0047] In the main chamber 21, when the pressure change therein tends to be stable and reaches the saturated vapor pressure, hydrogen will carry TCS from the main chamber 21 through the pipeline into the growth furnace 11. In order to maintain the stability of the growth gas flow entering the growth furnace 11 and ensure the consistency of the epitaxial layer thickness growth, PV3 and PV4 are opened or closed synchronously.

[0048] S2, process control after the epitaxial layer growth of the previous wafer is completed and before the epitaxial layer growth of the next wafer is completed.

[0049] S21, during the processing between two adjacent wafers, when the epitaxial layer processing of the previous wafer is completed, the controller 12 in the growth end 10 immediately starts and continuously transmits a refilling signal to the controller 2 24 in the auxiliary end 20. The controller 24 monitors the liquid level in the main chamber 21 through the liquid level sensor, and can determine whether the main chamber 21 needs to be refilled. The refilling logic is as follows: Figure 4 shown.

[0050] Specifically, after the film thickness of the epitaxial layer of each wafer is processed, the controller 1 12 directly sends a liquid replenishment signal ON to the controller 2 24 in the auxiliary end 20 through an electrical signal. The controller 2 24 monitors the liquid level in the main chamber 21 through a liquid level sensor placed in the main chamber 21, and transmits the monitored position height signal to the controller 2 24. The controller 2 24 determines whether the main chamber 21 needs liquid replenishment. If liquid replenishment is not required, PV3 and PV4 are kept open to ensure that the growth furnace 11 and the main chamber 21, as well as the secondary chamber 22 and the main chamber 21 are connected, hydrogen is continuously introduced into the main chamber 21, and the gas pressure in the main chamber 21 remains unchanged. If liquid replenishment is required, the controller 24 directly replenishes the main chamber 21 through an electrical signal. When the liquid replenishment is completed, PV3 and PV4 can be kept open, thereby ensuring that the pressure of the mixed growth gas entering the growth furnace 11 remains unchanged, thereby ensuring that the pressure when the epitaxial layer of the next wafer is grown is consistent with the pressure when the epitaxial layer of the previous wafer is grown, and the epitaxial layer of the wafer can be repeatedly and continuously grown.

[0051] In the prior art, after the epitaxial film growth process of the previous wafer is completed, if the liquid level sensor monitors that the liquid level in the main chamber 21 is lower than the low liquid level, it will directly feedback a signal of low liquid level to the controller 12 of the growth end 10; then the controller 12 directly transmits the liquid replenishment signal to the auxiliary end 20 through a pneumatic signal to replenish TCS; when the liquid level after replenishment is higher than the low liquid level, the auxiliary end 20 will feedback a full liquid level signal to the growth end 10, and the growth end 10 will then close the TCS liquid replenishment through the pneumatic valve through the controller 12. The existing liquid replenishment logic uses pneumatic signal transmission, which not only has a long feedback time, but also easily leads to the pressure of the main chamber 21 when the epitaxial film of the previous wafer is grown and the pressure of the main chamber 21 before the epitaxial film of the next wafer is grown, so that the pressure changes when hydrogen carries TCS into the growth furnace 11 to grow the epitaxial film of the next wafer, which will cause the growth rate to change, resulting in excessive pressure differences between furnaces in the thickness of the epitaxial layer, and no repeatability.

[0052] After the application proposes to change the liquid replenishment logic, electrical signals replace the existing pneumatic signals, which can not only shorten the feedback time and increase the startup speed, but also reduce the pressure changes caused by signal delays, thereby minimizing the pressure changes between furnaces, thereby ensuring the stability of the epitaxial layer growth rate between furnaces and improving repeatability.

[0053] S22: When the liquid level of TCS in the main chamber 21 is at a high level, there is no need to replenish liquid into the main chamber 21.

[0054] In this process, when the liquid level of TCS in the main chamber 21 is at a high level, the sensor monitoring the liquid level will directly transmit the liquid level to the controller 2 24, and the controller 2 24 will directly determine that there is no need to replenish liquid in the main chamber 21 based on the preset judgment conditions.

[0055] At this time, the growth furnace 11 and the main chamber 21 are kept connected, and the main chamber 21 and the sub-chamber 22 are kept connected. That is, when liquid replenishment is not needed, PV3 and PV4 are kept open, and the same hydrogen flow rate is continuously fed into the main chamber 21 to mix with TCS, and the same growth gas flow rate and pressure are continuously fed from the main chamber 21 into the growth furnace 11, waiting for the start of the next wafer epitaxial layer processing procedure.

[0056] S22 . When the liquid level of TCS in the main chamber 21 is at a low level, it is necessary to replenish liquid into the main chamber 21 .

[0057] Specifically, the growth end 10 sends a refill signal to the auxiliary end 20. When the liquid level of TCS in the main chamber 21 is at a low level, the sensor monitoring the liquid level will directly transmit it to the controller 2 24. The controller 2 24 directly determines that the main chamber 21 needs to be refilled based on the preset judgment conditions.

[0058] When liquid replenishment is needed, according to the preset pulse signal, the pressure relief control is performed while replenishing the liquid, and the operation is performed alternately until the TCS liquid level in the main chamber 21 reaches the high liquid level.

[0059] like Figure 4 As shown, the controller 24 sends a refilling signal to the auxiliary terminal 20 through an electrical signal, delays 0.1-0.3s to open PV2, connects the auxiliary chamber 23 with the main chamber 21, and introduces TCS into the main chamber 21 to start refilling.

[0060] After a period of time, the fluid replenishment is stopped, and the pressure relief valves PV6 and PV8 are opened to relieve the pressure of the main chamber 21 for a period of time;

[0061] Then open PV2 and close PV6 and PV8, replenish fluid for a while, then close PV2 and open PV6 and PV8 to release pressure for a while.

[0062] Repeat the above steps to alternately replenish and relieve the pressure in the main chamber 21; and the pulse replenishment time is the same as the pressure relief time, preferably, both are 5s. This alternating operation is performed until the TCS liquid level in the main chamber 21 reaches the high liquid level. Among them, the start and stop of PV2, PV6, and PV8 are controlled according to the preset pulse signal, and when the replenishment starts, the opening state of PV8 is determined by the current clock state.

[0063] During the liquid replenishment process, PV3 and PV4 are always closed, that is, the connecting pipes between the growth furnace 11 and the main chamber 21, and the connecting pipes between the main chamber 21 and the secondary chamber 22 are closed, and the growth gas is not introduced into the growth furnace 11 temporarily, and hydrogen is not introduced into the main chamber 21 to avoid affecting the monitoring of the TCS liquid level in the main chamber 21, and the bubbling of the main chamber 21 is suspended. When the growth furnace 11 and the main chamber 21 are connected, bubbling must be performed in the main chamber 21, which is conducive to hydrogen carrying TCS into the growth furnace 11.

[0064] In addition, when PV2 is opened to replenish fluid to the main chamber 21, the pressure relief valve PV6 is closed. When relieving pressure, PV8 must be opened while PV6 is opened, and accordingly, PV2 is closed synchronously. Since the main chamber 21 is a closed chamber, injecting TCS into it will cause the air pressure in the main chamber 21 to increase. In order to ensure the stability of the air pressure value in the main chamber 21 measured by the pressure gauge PT1, the main chamber 21 needs to be depressurized, and not continuously, to prevent excessive pressure relief from causing excessive changes in the internal pressure value. PV6 and PV8 are controlled by the same shopping signal to discharge the gas in the main chamber 21 into the exhaust gas treatment equipment. Accordingly, opposite pulse signals are used for fluid replenishment control for PV2 and PV6.

[0065] When the liquid level of TCS in the main chamber 21 reaches the high level, if PV2 is still in the open state at this time, the controller 24 will notify PV2 to close through an electrical signal and stop replenishing the liquid; since the air pressure in the main chamber 21 is relatively high, PV6 and PV8 should be controlled to release the pressure for the same time accordingly, so that the air pressure in the main chamber 21 is stable and kept consistent with the air pressure during the epitaxial layer growth; after the pressure is released, the replenishment is completed.

[0066] When the liquid level of TCS in the main chamber 21 reaches the high liquid level, if at this time, PV2 is closed, and PV6 and PV8 are relieving pressure, when the pressure in the main chamber 21 is consistent with the air pressure during the epitaxial layer growth, the pressure relief is stopped, PV6 and PV8 are closed, and the liquid replenishment is completed.

[0067] During the entire refilling process, regardless of whether the main chamber 21 needs refilling, the controller 1 11 in the growth end 10 always sends a refilling signal to the auxiliary end 20 through an electrical signal. The controller 2 24 determines whether it is necessary to provide refilling to the main chamber 21. Not only is the signal flow of the liquid level judgment and refilling control of the main chamber 21 optimized, but also each controller is directly connected to each chamber and air valve by using an electrical signal to replace the existing pneumatic signal control, so that the feedback time of the signal control is shortened to 0.1-0.3s, further shortening the buffering time of the refilling signal, and accurately and quickly refilling the solution in the main chamber 21. At the same time, the stability of the air pressure in the main chamber 21 can be ensured, so that during the epitaxial layer growth process of different wafers of the same batch in the main chamber 21, the pressure change is small, the stability of the epitaxial layer growth rate is ensured, and the difference between the furnaces of the epitaxial film thickness is small, that is, the thickness difference of the epitaxial film obtained after different wafers of the same batch are grown in the growth furnace 11 is small.

[0068] S23, starting the process of growing the epitaxial layer of the next wafer.

[0069] When the main chamber 21 receives the liquid replenishment signal OFF from the controller 12 or receives the signal that the liquid level of TCS in the main chamber 21 has reached the high liquid level monitored by the controller 24, the liquid replenishment is stopped as long as any one of the conditions is met, PV2, PV6 and PV8 are closed, and PV3 and PV4 are opened synchronously to control the connection between the growth furnace 11 and the main chamber 21, and the connection between the main chamber 21 and the secondary chamber 22. That is, when the liquid is being replenished, if the growth end 20 begins to prepare to grow the epitaxial layer of the next wafer, the liquid replenishment must be stopped, and the controller 12 will directly send the liquid replenishment signal OFF to the auxiliary end 10, and the liquid replenishment will be stopped. When the controller 24 monitors the signal that the liquid level of TCS in the main chamber 21 has reached the high liquid level, the liquid replenishment is stopped.

[0070] Furthermore, after the main chamber 21 receives the signal to close the liquid replenishment, it delays 0.1-0.3s, controls the main chamber 21 to start bubbling, and stops replenishing the liquid until the epitaxial layer processing of the next wafer starts.

[0071] The refilling method in the present application and the existing refilling method were used to conduct an experiment on the repeatability of epitaxial wafer thickness in an E320 epitaxial furnace, and 15 wafers of the same specifications were selected for testing respectively; all wafers were tested using the same growth process but different refilling methods.

[0072] After the growth is completed, 9 points are selected on the epitaxial layer of each wafer to measure its film thickness data, and the film thickness data of the wafer is processed to obtain the maximum film thickness max, the minimum film thickness min, the film thickness deviation value uni (calculation formula: max / min-1), and the average film thickness avg, so as to obtain the epitaxial layer film thickness data of 15 wafers. The film thickness data obtained by the liquid replenishment method in this application is shown in Table 1; accordingly, the average film thickness of each wafer is arranged, and the obtained linear trend diagram of the change is as shown in Table 1. Figure 5 As shown, in Figure 5 In the figure, the X-axis is the wafer number (slot 1 represents the first wafer, slot 2 represents the second wafer, and so on), and the Y-axis is the average film thickness of the epitaxial layer, in μm. At the same time, the pressure change value of the growth gas, i.e., hydrogen, carrying TCS into the growth furnace 11 during the film growth process of the epitaxial layer of each wafer is obtained to form a total pressure change trend diagram of the 15 wafers, as shown in FIG. Figure 6 As shown, the X-axis is the time taken for the epitaxial layer growth process of each wafer. Since 15 wafers are tested for growth one by one without interruption between furnaces, the time obtained is the actual recorded time of the growth of each wafer, that is, the time accumulated for each wafer based on the processing time of the previous wafer; the Y-axis is the pressure value of the growth gas entering the growth furnace 11 during film growth.

[0073] Table 1 Film thickness data obtained by the rehydration method proposed in this application (μm)

[0074]

[0075] By adopting the liquid replenishment method proposed in the prior art and the same operation as the above-mentioned processing method, the film thickness data of 15 wafers are obtained, as shown in Table 2; accordingly, the average film thickness of each wafer is arranged, and the obtained linear trend diagram is as shown in Table 2. Figure 7 As shown; during the film growth process, the growth gas, ie, hydrogen, carries TCS into the growth furnace 11, and the pressure change trend diagram is as follows: Figure 8 shown.

[0076] Table 2 Film thickness data obtained by the prior art rehydration method (μm)

[0077]

[0078] From the above test results, it can be seen that the method can obtain a repeatable and stable furnace pressure. In addition to meeting the requirements for wafer processing flow, the dynamic pressure variation of the growth gas of hydrogen carrying TCS is small. The pressure fluctuation range of the growth gas between the epitaxial wafer furnaces is reduced to <0.5psi; the film thickness of the epitaxial layer of the wafer has good repeatability, and the furnace deviation is <0.5%, which not only improves the product quality, but also ensures the product processing performance and achieves stable mass production; at the same time, it also reduces the pressure fluctuation of the growth gas, that is, the dynamic hydrogen carrying TCS, during the process, which can meet the long film quality requirements of the 2-5μm epitaxial layer and broaden the process processing capabilities of the epitaxial equipment.

[0079] The refilling method proposed in this application also reduces the difference in epitaxial layer thickness of each wafer in the same batch, ensuring the consistency of epitaxial film growth rate of each wafer. The inter-furnace film thickness deviation of 1.0-2.0% in the prior art is reduced to less than 0.5% (calculation formula: max / min-1), which improves the overall yield of epitaxial wafers and successfully solves the technical problem of excessive inter-furnace film thickness deviation in current epitaxial furnaces, such as model E320.

[0080] The start and stop of the gas valve is controlled by electrical signals, replacing the existing pneumatic signals. The conversion time is fast and stable, which ensures the operation time of the equipment, reduces the downtime of equipment failure, and realizes the maximum mass production of the equipment.

[0081] A liquid replenishing method for wafer epitaxial layer processing designed by the present invention can ensure that the pressure fluctuation between epitaxial wafer furnaces is controlled from the existing ±1.5psi to ±0.2psi, and the uniformity between epitaxial wafer furnaces is optimized from the original >1.0% to <0.5% (calculation formula: max / min-1), which converges the fluctuation between epitaxial wafer furnaces, improves the film forming quality of the epitaxial layer, has a significant film forming effect between furnaces, has good repeatability between furnaces, improves production efficiency, and saves production costs.

[0082] The above embodiments of the present invention are described in detail, and the contents are only preferred embodiments of the present invention, and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for replenishing liquid in wafer epitaxial layer processing, comprising: The growth end is used for growing epitaxial layers of wafers and is provided with a growth furnace; the auxiliary end is used for providing growth gas to the growth end and is provided with a main chamber for storing growth gas, a secondary chamber for providing hydrogen to the main chamber, and an auxiliary chamber for providing TCS to the main chamber; the steps include: During the processing between two adjacent wafers, when the epitaxial layer processing of the previous wafer is completed, the growth end continuously sends a liquid replenishment signal to the main chamber, and the auxiliary end determines whether the main chamber needs liquid replenishment; If no refilling is needed, wait for the next wafer epitaxial layer processing; If rehydration is necessary, add solution to the main chamber; Wherein, when liquid replenishment is not required, the growth furnace is kept in communication with the main chamber, and the main chamber is kept in communication with the secondary chamber; The growth end sends a refill signal to the auxiliary end. When the liquid level of the TCS in the main chamber is at a low level, the sensor monitoring the liquid level will directly transmit it to the controller 2 at the auxiliary end. Then, based on the preset judgment conditions, the controller 2 directly determines that the main chamber needs to be refilled. When the liquid level of TCS in the main chamber is at a high level, the sensor monitoring the liquid level will directly transmit the liquid level to the controller 2, and the controller 2 will directly determine that there is no need to replenish the main chamber based on the preset judgment conditions; When rehydration is needed, it includes: After the main chamber receives the liquid replenishment signal ON, it delays 0.1-0.3s, connects the auxiliary chamber with the main chamber to start liquid replenishment, and stops bubbling in the main chamber; When replenishing fluid, the operation is performed alternately according to the preset replenishment signal and pressure relief signal until the TCS liquid level in the main chamber reaches the high liquid level; When the main chamber receives the refill signal OFF, it delays 0.1-0.3s, controls the main chamber to start bubbling, and stops refilling; Until the epitaxial layer processing of the next wafer begins.

2. A method for replenishing liquid in wafer epitaxial layer processing according to claim 1, characterized in that: When the liquid level of TCS in the main chamber is at a high level, no liquid replenishment is required; When the liquid level of TCS in the main chamber is at a low level, it needs to be replenished.

3. A method for replenishing liquid in wafer epitaxial layer processing according to claim 1 or 2, characterized in that: When rehydrating, alternate the rehydration time with the same pressure relief time.

4. A method for replenishing liquid in wafer epitaxial layer processing according to claim 3, characterized in that: The alternating fluid infusion time and pressure relief time were both 5s.

5. A method for replenishing liquid in wafer epitaxial layer processing according to any one of claims 1 to 2 and 4, characterized in that: The controller that provides the fluid replenishment signal to the main chamber is connected to the secondary chamber and the auxiliary chamber through electrical signals.

6. A method for replenishing liquid in wafer epitaxial layer processing according to claim 5, characterized in that: The controller that provides the refill signal to the main chamber is connected to the gas valves on all the pipelines in the auxiliary end through electrical signals.

7. A method for replenishing liquid in wafer epitaxial layer processing according to claim 6, characterized in that: The controller that provides a growth signal to the growth furnace is connected to the controller that provides a liquid replenishment signal to the main chamber through an electrical signal.

8. A method for replenishing liquid in wafer epitaxial layer processing according to any one of claims 1-2, 4, 6-7, characterized in that: When the main chamber receives a signal to close the liquid replenishment or the liquid level of TCS in the main chamber reaches a high liquid level, the liquid replenishment is stopped, and the growth furnace is controlled to be connected with the main chamber, and the main chamber is controlled to be connected with the secondary chamber.

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