Cleaning method of low-pressure chemical vapor deposition doped polycrystalline silicon process equipment

Abstract

The invention discloses a method for cleaning low-pressure chemical vapor deposition doped polycrystalline silicon process equipment. The method comprises the following steps: 1) replacing gas in the equipment with inert gas; (2) introducing ClF3 gas; (3) displaying the temperature of gas in the monitoring equipment; 4) when the temperature of the gas in the equipment is at a drop inflection point, recording the cleaning time, and finishing the front end point grabbing; and (5) when the temperature of the gas in the equipment is reduced to a preset temperature value, recording the cleaning time at the moment, increasing the inert flow and reducing the flow of the ClF3 gas, and finishing grabbing. According to the method, the exothermic effect of chemical reaction of online cleaning gas ClF3 and doped polycrystalline silicon and the gas temperature control principle in equipment of a low-pressure diffusion furnace are utilized, the terminal point can be captured through feedback signals of the real-time temperature of a furnace chamber in the online cleaning process, then the flow of the ClF3 gas is reduced 3 minutes before the terminal point, and meanwhile a large amount of inert gas is introduced; the concentration of ClF3 gas in the atmosphere environment is greatly reduced, the chemical reaction rate is reduced, and damage to quartz spare parts is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of a cleaning method for low-pressure chemical vapor deposition doped polysilicon process equipment, and in particular to a cleaning method for low-pressure chemical vapor deposition doped polysilicon process equipment. Background Art

[0002] In the field of semiconductor manufacturing, LPCVD D-Poly (low-pressure chemical vapor deposition doped polysilicon) technology is often used for thin film deposition. Thin film deposition is not limited to the chip surface, but also deposited on the quartz chamber, carrier boat, etc. (hereinafter collectively referred to as quartz spare parts) and fixture surfaces in the process environment. When the film accumulates to a certain thickness, the deposited film needs to be passed through ClF 3 The gas online dry etching method is used to remove it, which avoids cracking and shedding of the film and causes serious particle contamination. However, because the quartz spare parts are composed of silicon dioxide, inorganic non-metallic fluorides will also react chemically with it. When using ClF 3 There are two major drawbacks in the gas online cleaning method. On the one hand, there is incomplete cleaning, which leads to particle breeding and pollution. On the other hand, there is excessive cleaning, which causes damage to quartz parts such as the quartz cavity and the carrier boat. Summary of the invention

[0003] The present invention aims to overcome the problem of using ClF in the prior art. 3 There are two major drawbacks in the gas online cleaning method. On the one hand, there is incomplete cleaning, which leads to particle breeding and pollution. On the other hand, there is excessive cleaning, which causes damage to quartz parts such as quartz chambers and carrier boats. A cleaning method for low-pressure chemical vapor deposition doped polysilicon process equipment is provided, which has the advantages of using online cleaning gas ClF 3 Due to the exothermic effect of the chemical reaction of doped polysilicon and the gas temperature control principle in the low-pressure diffusion furnace, the endpoint can be captured through the feedback signal of the temperature of the furnace chamber during the online cleaning process, and then the ClF can be reduced 3 minutes before the endpoint. 3 The gas flow rate is increased and a large amount of inert gas is introduced at the same time, which greatly reduces the ClF in the atmosphere 3 Gas concentration, reducing chemical reaction rate, reducing damage to quartz parts, etc.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment comprises the following steps: 1) Use inert gas to replace the gas in the equipment; 2) Pass ClF 3 gas; 3) Monitor the gas temperature display in the equipment; 4) When the gas temperature in the equipment is at the falling inflection point, record the cleaning time and the front end point capture is completed; 5) When the gas temperature in the equipment drops to the preset temperature value, record the cleaning time at this time, increase the inert flow rate and reduce the ClF 3 Gas flow, end point capture completed.

[0005] Preferably, in step 1), after replacing the gas, the gas pressure in the equipment is stabilized.

[0006] Preferably, in step 5), the flow rate of the inert gas is reduced and the flow rate of the ClF3 gas is increased. In step 2), the inert gas is adjusted to 1.0-10S SLM, and the CLF is opened. 3 Air valve, into CLF 3 0.5-5.0SLM, adjust the temperature setting value to 525-550℃.

[0007] Preferably, in step 1), the device standby temperature is reset simultaneously.

[0008] Preferably, in step 3), the heating body work is simultaneously recorded.

[0009] Preferably, in step 4), the heating work when the gas temperature in the equipment is at a decreasing inflection point is simultaneously recorded.

[0010] Preferably, in step 5), the heating work when the gas temperature in the equipment drops to a predetermined temperature value is recorded simultaneously.

[0011] Preferably, in step 5), the inert flow rate is increased and the ClF is reduced. 3 The gas flow rate is increased until the reaction rate drops to about 5-35% of the original rate.

[0011] Preferably, the cleaning is stopped after step 5), and the ClF is turned off. 3 Gas valve; after stopping cleaning, use inert gas to replace the remaining gas; finally, back pressure and temperature are restored.

[0013] The beneficial effects of the present invention are as follows: (1) the present invention utilizes the online cleaning gas ClF 3 Due to the exothermic effect of the chemical reaction of doped polysilicon and the gas temperature control principle in the low-pressure diffusion furnace, the endpoint can be captured through the feedback signal of the temperature of the furnace chamber during the online cleaning process, and then the ClF can be reduced 3 minutes before the endpoint. 3 The gas flow rate is increased and a large amount of inert gas is introduced at the same time, which greatly reduces the ClF in the atmosphere 3Gas concentration, chemical reaction rate is reduced, and quartz spare parts damage is reduced. (1) The present invention further monitors the furnace temperature and heating body work at the same time, and the cleaning endpoint is clear and easy to control by grabbing; (2) The quartz spare parts of the present invention are cleaned more cleanly and less damaged; (3) The present invention is not limited by the thickness of the thin film deposition on the quartz spare parts and the dry cleaning etching rate, and the application is more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the online cleaning process of Example 4 of the present invention. Figure 2 It is a schematic diagram of the process temperature curve and heating power curve of Example 4 of the present invention. Figure 3 This is a schematic diagram of the LPCVD D-Pol process equipment structure of the present invention. Figure 4 It is a working principle diagram of the temperature treatment system of the LPCVD D-Pol process equipment of the present invention.

[0015] That Figure 1 1. Cleaning process, 2. Pre-end grabbing, 3. End grabbing. Figure 2 1. Cleaning constant temperature, constant power section, 2. Temperature drop, power increase section, 3. End point constant temperature, constant power section. Figure 3 Middle: 1. Heater (heating body); 2. LinerTube (outer tube); 3. Inner Tube (inner tube); 4. Spike T / C (temperature control thermocouple), divided into five points: S1, S2, S3, S4, and S5; 5. Inner T / C (temperature monitoring thermocouple), divided into five points: I1, I2, I3, I4, and I5. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. In the present invention, the equipment in the present invention is a low-pressure diffusion furnace. In the present invention, LPCVD (Low Pressure Chemical Vapor Deposition) is a technology that allows gaseous chemical precursors (reaction gases) to react chemically on the surface of a substrate under a pressure lower than normal pressure to deposit and form a thin film. Pol refers to polycrystalline silicon.

[0017] In the present invention, CLF 3 When it is passed into the pressure diffusion furnace, the chemical reaction formula is: 4Si+4CLF 3 →SiCL 4 +3SiF 4 + Heat.

[0018] In the present invention, SLM is the abbreviation of Standard Liter per Minute, i.e. standard liter per minute.

[0019] Embodiment 1: A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment, comprising the following steps: 1) replacing the gas in the equipment with an inert gas, and stabilizing the pressure in the equipment after replacing the gas; 2) introducing ClF 3 3) Monitor the temperature of the gas in the equipment; 4) When the temperature of the gas in the equipment is at the inflection point of the decline, record the cleaning time and complete the front end point capture; 5) When the temperature of the gas in the equipment drops to the predetermined temperature value, record the cleaning time at this time, increase the inert flow rate and reduce the ClF 3 Gas flow, end point capture is completed. 6) Cleaning stops, turn off ClF 3 7) Use inert gas to replace the remaining gas; finally, return the pressure and temperature.

[0020] Embodiment 2: A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment, comprising the following steps: 1) using an inert gas to replace the gas in the equipment and resetting the standby temperature of the equipment. After the gas is replaced, the pressure in the equipment is stabilized; 2) introducing ClF 3 Gas, in which the inert gas is 1.0SLM, open CLF 3 Air valve, into CLF 3 0.5SLM, adjust the temperature setting value to 525℃; 3) Monitor the gas temperature display in the equipment; 4) When the gas temperature in the equipment is at the inflection point of the decline, record the cleaning time, and the front end point capture is completed; 5) When the gas temperature in the equipment drops to the predetermined temperature value, record the cleaning time at this time, increase the inert flow rate and reduce ClF 3 Gas flow, end point capture is completed. 6) Cleaning stops, turn off ClF 3 7) Use inert gas to replace the remaining gas; finally, return the pressure and temperature.

[0021] Embodiment 3: A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment, comprising the following steps: 1) using an inert gas to replace the gas in the equipment and resetting the standby temperature of the equipment. After the gas is replaced, the pressure in the equipment is stabilized; 2) introducing ClF 3 Gas, of which the inert gas is 10.4SLM, open CLF 3 Air valve, into CLF 35.0SLM, adjust the temperature setting value to 550℃; 3) Monitor the gas temperature display in the equipment; 4) When the gas temperature in the equipment is at the inflection point of the decline, record the cleaning time, and the front end point capture is completed; 5) When the gas temperature in the equipment drops to the predetermined temperature value, record the cleaning time at this time, increase the inert flow rate and reduce ClF 3 Gas flow, end point capture is completed. 6) Cleaning stops, turn off ClF 3 7) Use inert gas to replace the remaining gas; finally, return the pressure and temperature.

[0022] Embodiment 4: Figure 1 and Figure 2 As shown, a cleaning method for low-pressure chemical vapor deposition doped polysilicon process equipment includes the following steps: 1) using an inert gas to replace the gas in the equipment and resetting the standby temperature of the equipment. After the gas is replaced, the pressure in the equipment is stabilized; 2) introducing ClF 3 Gas, of which the inert gas is 3.2SLM, open CLF 3 Air valve, into CLF 3 1.8SLM, adjust the temperature setting value to 535℃; 3) Monitor the gas temperature display in the equipment and record the heating work at the same time, with a collection frequency of 5 times / Min; 4) When the gas temperature in the equipment is at the inflection point of the decline, record the cleaning time and record the heating work when the gas temperature in the equipment is at the inflection point of the decline; the front end point capture is completed; 5) When the gas temperature in the equipment is at the predetermined temperature value, record the cleaning time at this time and record the heating work when the gas temperature in the equipment is at the predetermined temperature value; increase the inert flow rate and reduce ClF 3 Gas flow, end point capture is completed. 6) Cleaning stops, turn off ClF 3 7) Use inert gas to replace the remaining gas; finally, return the pressure and temperature.

[0023] In this embodiment, the front end point is captured. At this time, the exothermic reaction is nearing the end, and the first furnace temperature drop inflection point appears to reduce the main cleaning gas ClF 3 The flow rate was reduced and the nitrogen flow rate was increased at the same time until the reaction rate dropped to 5% of the original rate.

[0024] The schematic diagram of the online cleaning process of this embodiment is as follows Figure 1 As shown, the process temperature curve and heating power curve are shown in Figure 2 shown.

[0025] Embodiment 5: A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment, comprising the following steps: 1) using an inert gas to replace the gas in the equipment and resetting the standby temperature of the equipment. After the gas is replaced, the pressure in the equipment is stabilized; 2) introducing ClF3 Gas, of which the inert gas is 3.2SLM, open CLF 3 Air valve, into CLF 3 1.8SLM, adjust the temperature setting value to 535℃; 3) Monitor the gas temperature display in the equipment and record the heating work at the same time, with a collection frequency of 10 times / Min; 4) When the gas temperature in the equipment is at the inflection point of the decline, record the cleaning time and record the heating work when the gas temperature in the equipment is at the inflection point of the decline; the front end point capture is completed; 5) When the gas temperature in the equipment is at the predetermined temperature value, record the cleaning time at this time and record the heating work when the gas temperature in the equipment is at the predetermined temperature value; increase the inert flow rate and reduce ClF 3 Gas flow, end point capture is completed. 6) Cleaning stops, turn off ClF 3 7) Use inert gas to replace the remaining gas; finally, return the pressure and temperature.

[0026] In this embodiment, the front end point is captured. At this time, the exothermic reaction is nearing the end, and the first furnace temperature drop inflection point appears to reduce the main cleaning gas ClF 3 flow rate, and at the same time increase the nitrogen flow rate until the reaction rate drops to 35% of the original rate

[0027] In one embodiment of the present invention, in step 6), CLF is turned off. 3 Gas valve, adjust the nitrogen flow rate to 8SLM.

[0028] In one embodiment of the present invention, when an inert gas is used to replace the gas in the equipment in step 1), the specific steps include: step a: nitrogen flow, cooling: open the nitrogen valve and reset the standby temperature; step b: drive out: repeat three times. Step c: background vacuum: close the nitrogen valve. Step d: leak rate detection: close the large valve; step e: voltage stabilization: open the large valve, open the nitrogen valve and set a fixed nitrogen flow rate. In the specific step a, 8SLM (L / Min) of nitrogen is introduced and the standby temperature is set to 400°C.

[0029] In one embodiment of the present invention, in step b, first close the nitrogen valve, evacuate to less than 1 Torr, close the large valve, introduce 4 SLM of nitrogen and increase the pressure to 400 Torr, and repeat three times.

[0030] In one embodiment of the present invention, in step c, the nitrogen valve is closed and vacuum pumping is performed for 10 to 15 minutes to achieve a background vacuum of less than 5 mTorr.

[0031] In one embodiment of the present invention, in step d, the large valve is closed and the pressure rise within 1 minute is detected.

[0032] In one embodiment of the present invention, in step e, the nitrogen valve is opened, 5 SLM of nitrogen is introduced, and the pressure is stabilized at 1 Torr.

[0032] Step 7) The specific operation is: Drive out: Repeat three times. Back pressure: Open the nitrogen valve. Rewarming: Reset the standby temperature. When the pressure rises to 400Torr, close the nitrogen valve, when the pressure drops to <100mTorr, open the nitrogen valve, when the pressure rises to 400Torr, close the nitrogen valve, when the pressure drops to <1Torr, open the nitrogen valve, when the pressure rises to 400Torr, close the nitrogen valve, when the pressure drops to <10Torr, open the nitrogen valve. During the back pressure operation, close the large valve, adjust the nitrogen flow rate to 4SLM, and the pressure returns to atmospheric pressure. During the rewarming operation, adjust the nitrogen flow rate to 8SLM, and the standby temperature is set to 550°C.

[0034] In one embodiment of the present invention, Figure 3 , Figure 4 As shown, a temperature processing system for LPCVD D-Pol process equipment in the present invention includes a temperature processor, and the temperature processor is used to collect Inner T / C, Setpoint (set value) signal and Spike T / C (select signal sample "W3" (third point output power)). When it is working, "Signal 1" in the figure: the temperature processor collects the Inner T / C signal (selects the signal sample "I3") and the Setpoint (set value) signal (selects the signal sample "P3") to perform logic operations, and when I3<P3, the temperature processor gives the Spike T / C (selects the signal sample "W3" (third point output power)) a heating signal, at this time W3>0; "Signal 2" in the figure: on the contrary, the temperature processor collects the Inner T / C signal (selects the signal sample "I3") and the Setpoint (set value) signal (selects the signal sample "P3") to perform logic operations, and when I3>P3>3℃, the temperature processor does not give the Spike T / C a heating signal, and at this time W3=0.

[0035] The above description is only a preferred embodiment of the present invention, and does not limit the patent protection scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention and the drawings, directly or indirectly used in other related technical fields, is also included in the protection scope of the present invention.

Claims

1. A method for cleaning low-pressure chemical vapor deposition doped polysilicon process equipment, characterized in that: The following steps are involved: 1) Use inert gas to replace the gas in the equipment; 2) Passing ClF3 gas; 3) Monitor the gas temperature display in the equipment; 4) When the gas temperature in the equipment is at the falling inflection point, record the cleaning time and the front end point capture is completed; 5) When the gas temperature in the equipment drops to the predetermined temperature value, the cleaning time is recorded, the inert gas flow rate is increased and the ClF3 gas flow rate is reduced, and the end point capture is completed.

2. The cleaning method of low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, characterized in that: In the step 1), after replacing the gas, the gas pressure in the device is stabilized.

3. The cleaning method of low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, characterized in that: In the step 5), the flow rate of the inert gas is reduced and the flow rate of the ClF3 gas is increased.

4. The method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, characterized in that: In the step 2), the inert gas is adjusted to 1.0-10 SLM, the CLF3 gas valve is opened, CLF3 0.5-5.0 SLM is introduced, and the temperature setting value is adjusted to 525-550°C.

5. A method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, 2, 3 or 4, characterized in that: In the step 1), the device standby temperature is reset at the same time.

6. A method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, 2, 3 or 4, characterized in that: In the step 3), the heating body work is recorded simultaneously.

7. The method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 6, characterized in that: In the step 4), the heating work when the gas temperature in the equipment is at the falling inflection point is simultaneously recorded.

8. The method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 7, characterized in that: In the step 5), the heating work when the temperature of the gas in the equipment drops to a predetermined temperature value is simultaneously recorded.

9. A method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, 2, 3 or 4, characterized in that: In step 5), the inert gas flow rate is increased and the ClF3 gas flow rate is decreased until the reaction rate is reduced to about 5-35% of the original rate.

10. A method for cleaning low pressure chemical vapor deposition doped polysilicon process equipment according to claim 1, 2, 3 or 4, characterized in that: After step 5), the cleaning is stopped, the ClF3 gas valve is closed, and after the cleaning is stopped, the remaining gas is replaced with an inert gas; and finally, the pressure and temperature are returned.

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