A cleaning method for semiconductor coating process chamber

Abstract

The present invention discloses a cleaning method for a semiconductor coating process chamber, the cleaning method comprising the following steps: (1) introducing argon into the process chamber, and turning on a radio frequency power source to apply radio frequency energy into the process chamber to excite the argon into plasma; (2) introducing a reaction gas into the process chamber while continuously applying radio frequency energy to react with the byproducts remaining from the coating in the chamber; the reaction gas comprises octafluorocyclobutane, nitrous oxide and nitrogen; (3) after the reaction is completed, introducing nitrogen into the process chamber to remove the dirt remaining in the chamber. The present invention first introduces argon into the process chamber to ignite plasma, pre-forms a plasma environment for the reaction gas to promote the reaction between the reaction gas and the byproducts, and simultaneously introduces nitrogen into the reaction gas to quickly and evenly disperse the reaction gas in the chamber, thereby effectively shortening the cleaning time, reducing the loss of special gases, and effectively reducing the cost of tail gas recovery.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor coating device cleaning, and in particular to a cleaning method for a semiconductor coating process chamber. Background Art

[0002] With the development of semiconductor technology, the characteristic size of semiconductor components is getting smaller and smaller, and the corresponding requirements for semiconductor processing technology are getting higher and higher. Among them, plasma enhanced chemical vapor deposition (PECVD) is widely used in semiconductor coating processes. By introducing the material source into the process chamber in the form of gas, under the condition of radio frequency processing rate, the reaction gas obtains activation energy from the plasma field corresponding to the glow discharge, activates and enhances the chemical reaction, thereby realizing chemical vapor deposition. However, in the actual production process, PECVD equipment not only deposits thin films on the surface of the wafer, but also deposits on the surface of the processing chamber. When the chamber is used for a long time, as the coating by-products on the inner wall of the chamber increase, excessive by-product residues will produce particles due to plasma bombardment, thereby affecting the coating yield. Therefore, the control of chamber cleanliness in the semiconductor coating process is one of the key factors in controlling the yield.

[0003] In order to ensure the quality of the deposited film, the process chamber needs to be cleaned. In the early days, nitrogen trifluoride (NF3) and inert gas were usually used to clean the deposited SiO2, Si3N4, SiO x N y The NF3 gas is plasmatized and dissociated into F ions or F radicals, which react with SiO2, Si3N4 or SiO x N y Reaction to generate SiF4, CO2, N2, F2, etc., thereby achieving effective cleaning of the chamber. However, NF3 as a cleaning gas has problems such as high cost and long cleaning time, and is not suitable for cleaning equipment in industrial production. In addition to the above-mentioned NF3 gas, fluorinated carbon compounds have stable chemical properties, low boiling points, are harmless to the human body and are non-flammable. In addition, research has found that the combination of carbon fluoride gases C2F6 and O2 can dissociate into fluorine free radicals after plasma treatment, which react with SiO2, Si3N4, SiO x N y The reaction generates SiF4 gas, while O2 reacts with C to generate CO and CO2 gases, so fluorinated carbon compounds can replace NF3 as cleaning gas. However, the current use of carbon fluoride gases as F source for cleaning chambers still has the problem of long cleaning time and low utilization rate (such as C2F6), which causes waste of special gases and increases the cost of tail gas treatment. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a cleaning method for a semiconductor coating process chamber. Before the reaction gas is introduced into the process chamber, argon gas is first introduced and argon plasma is generated under radio frequency energy. When the reaction gas is introduced into the process chamber, it is ignited by the argon plasma to quickly generate a plasma environment of the reaction gas, thereby effectively shortening the cleaning time.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a cleaning method for a semiconductor coating process chamber, the cleaning method comprising the following steps:

[0007] (1) introducing argon gas into the process chamber and turning on the radio frequency power source to excite the argon gas into plasma;

[0008] (2) introducing a reaction gas into the process chamber under continuous application of radio frequency power to react with residual byproducts of the coating in the chamber; the reaction gas comprises octafluorocyclobutane, nitrous oxide and nitrogen;

[0009] (3) After the reaction is completed, nitrogen is introduced into the process chamber to remove the remaining dirt in the chamber.

[0010] Furthermore, in step (1), the flow rate of the introduced argon gas is 100 to 200 sccm, and the time is 2 to 8 s.

[0011] Furthermore, in step (2), the flow rate of octafluorocyclobutane is 4 to 15 sccm, and the time is 50 to 300 s.

[0012] Furthermore, in step (2), the flow rate of nitrous oxide is 5 to 50 sccm, and the time is 50 to 300 s.

[0013] The present invention first introduces argon gas into the process chamber to generate argon plasma through plasmaization. The argon plasma with strong physical bombardment can prompt the reaction gas to quickly generate a plasma environment, thereby accelerating the reaction of C4F8, N2O and by-products (SiO2, Si3N4, SiO x N y ) to produce SiF4, CO2 and N2.

[0014] Furthermore, in step (2), the flow rate of nitrogen is 300 to 1000 sccm, and the time is 50 to 300 seconds. Nitrogen is introduced into the reaction gas octafluorocyclobutane and nitrous oxide. The presence of nitrogen can evenly mix the reaction gas, so that the reaction gas quickly fills the chamber. At the same time, the adsorption heat of nitrogen is small, and the residence time on the surface of the chamber is short, so some by-products can be removed.

[0015] Furthermore, in step (2), argon gas is continuously introduced while the reaction gas is introduced, and the flow rate of the argon gas is 100 to 200 sccm for 50 to 300 s.

[0016] Furthermore, in step (2), the by-product comprises SiO2, Si3N4 or SiO x N y One or more of , x, y>0.

[0017] Furthermore, in step (3), the flow rate of nitrogen gas is 300 to 1000 sccm, and the time is 10 to 20 s.

[0018] Furthermore, the radio frequency power is 20-200W and the frequency is 13.56MHz.

[0019] Furthermore, during the cleaning process, a constant temperature and pressure are maintained in the process chamber, wherein the temperature of the process chamber is 200-350° C. and the pressure is 1-3 Torr.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention provides a cleaning method for a semiconductor coating process chamber, wherein argon gas is first introduced and argon plasma is generated under radio frequency energy. When the reaction gas is introduced into the process chamber, it is ignited by the argon plasma to quickly generate a plasma environment of the reaction gas, thereby effectively shortening the cleaning time. In addition, nitrogen gas is introduced into the reaction gas, and the reaction rate is adjusted by the introduction of nitrogen gas. The characteristics of nitrogen gas, such as low adsorption heat and short residence time on the chamber surface, are utilized to remove some by-products, thereby further improving the cleaning efficiency.

[0022] 2. The present invention adopts a combination of octafluorocyclobutane and nitrous oxide as a reaction gas for cleaning the silicon-based film remaining in the chamber. Compared with using NF3 or C2F6 as a cleaning gas, the combination of the cleaning method and the reaction gas described in the present invention can effectively improve the utilization rate of the cleaning gas and reduce the generation of the reaction by-product CF4, thereby effectively reducing the use of special gases and the cost of waste gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The distribution of the duration of different gases being introduced during the cleaning process;

[0024] Figure 2 The cleaning rate of the deposited film on the chamber surface by different cleaning methods. DETAILED DESCRIPTION

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0027] Example 1

[0028] This embodiment relates to a cleaning method for a semiconductor coating process chamber, using a combination of octafluorocyclobutane and nitrous oxide as a cleaning gas to clean the chamber after coating (alternating growth of SiO2 and Si3N4 films 6 times, with a film thickness of 300 nm), and the specific operation is as follows:

[0029] (1) Argon gas was introduced into the process chamber at a flow rate of 150 sccm, and the RF power source was turned on to apply RF energy into the process chamber to excite the argon gas into plasma; the RF power was set to 200 W, the RF frequency was set to 13.56 MHz, the temperature in the chamber was set to 300 °C, and the pressure was set to 1 Torr;

[0030] (2) After the argon gas is introduced into the process chamber for 5 seconds in step (1), octafluorocyclobutane, nitrous oxide and nitrogen are introduced into the process chamber while continuing to introduce argon gas into the process chamber under continuous application of radio frequency energy, and the reaction gases octafluorocyclobutane and nitrous oxide react with SiO2 and Si3N4 to generate gaseous SiF4, which is discharged out of the reaction chamber; wherein the flow rate of octafluorocyclobutane is set to 10 sccm, the flow rate of nitrous oxide is set to 40 sccm, and the flow rate of nitrogen is set to 800 sccm;

[0031] (3) The reaction gas was introduced for 150 seconds until the reaction was complete, and nitrogen was continuously introduced into the process chamber for 20 seconds to remove the residual substances in the chamber.

[0032] Example 2

[0033] This embodiment relates to a cleaning method for a semiconductor coating process chamber, using a combination of octafluorocyclobutane and nitrous oxide as a cleaning gas to clean the chamber after coating (alternating growth of SiO2 and Si3N4 films 6 times, with a film thickness of 300 nm). The only difference from the embodiment 1 is that the operation of step (1) is not included, specifically:

[0034] (1) introducing octafluorocyclobutane, nitrous oxide, nitrogen and argon into the process chamber, and turning on the RF power source to apply RF energy into the process chamber, so that the reaction gases octafluorocyclobutane and nitrous oxide react with SiO2 and Si3N4 to generate gaseous SiF4, which is discharged out of the reaction chamber; wherein the flow rate of octafluorocyclobutane is set to 10sccm, the flow rate of nitrous oxide is set to 40sccm, the flow rate of nitrogen is set to 800sccm, and the flow rate of argon is set to 150sccm; setting the RF power to 200W, the RF frequency to 13.56MHz, the temperature in the chamber to 300°C, and the pressure to 1Torr;

[0035] (2) The reaction gas was introduced for 174 seconds until the reaction was complete, and nitrogen was continuously introduced into the process chamber for 20 seconds to remove the residual substances in the chamber.

[0036] Example 3

[0037] This embodiment relates to a cleaning method for a semiconductor coating process chamber, using a combination of octafluorocyclobutane and nitrous oxide as a cleaning gas to clean the chamber after coating (alternating growth of SiO2 and Si3N4 films 6 times, with a film thickness of 300 nm). The only difference from the embodiment 1 is that the gas introduced in step (2) does not contain nitrogen, as follows:

[0038] (1) Argon gas was introduced into the process chamber at a flow rate of 150 sccm, and the RF power source was turned on to apply RF energy into the process chamber to excite the argon gas into plasma; the RF power was set to 200 W, the RF frequency was set to 13.56 MHz, the temperature in the chamber was set to 300 °C, and the pressure was set to 1 Torr;

[0039] (2) After the argon gas is introduced for 5 seconds in step (1), octafluorocyclobutane and nitrous oxide are introduced into the process chamber while continuing to introduce argon gas into the process chamber under continuous application of radio frequency energy, and the reaction gases octafluorocyclobutane and nitrous oxide react with SiO2 and Si3N4 to generate gaseous SiF4, which is discharged out of the reaction chamber; wherein the flow rate of octafluorocyclobutane is set to 10 sccm, and the flow rate of nitrous oxide is set to 40 sccm;

[0040] (3) The reaction gas was introduced for 182 seconds until the reaction was complete, and nitrogen was continuously introduced into the process chamber for 20 seconds to remove the residual substances in the chamber.

[0041] Comparative Example 1

[0042] This comparative example relates to a cleaning method for a semiconductor coating process chamber, using NF3 as a cleaning gas to clean the chamber after coating (alternating growth of SiO2 and Si3N4 films 6 times, with a film thickness of 300nm), as follows:

[0043] (1) nitrogen trifluoride and argon are introduced into the process chamber, and the RF power source is turned on to apply RF energy into the process chamber. The reaction gas nitrogen trifluoride reacts with SiO2 and Si3N4 to generate gaseous SiF4, which is discharged out of the reaction chamber; wherein the flow rate of nitrogen trifluoride is set to 7sccm, and the flow rate of argon is set to 150sccm; the RF power is set to 200W, the RF frequency is set to 13.56MHz, the temperature in the chamber is set to 300°C, and the pressure is set to 1Torr;

[0044] (2) The reaction gas was introduced for 200 seconds until the reaction was complete.

[0045] Comparative Example 2

[0046] This comparative example relates to a cleaning method for a semiconductor coating process chamber, using a combination of C2F6 and oxygen as a cleaning gas to clean the chamber after coating (alternating growth of SiO2 and Si3N4 films 6 times, with a film thickness of 300nm), as follows:

[0047] (1) Hexafluoroethane and oxygen are introduced into the process chamber, and the radio frequency power source is turned on to apply radio frequency energy into the process chamber. The reaction gases hexafluoroethane and oxygen react with SiO2 and Si3N4 to generate gaseous SiF4, which is discharged out of the reaction chamber; wherein the flow rate of hexafluoroethane is set to 10 sccm, and the flow rate of oxygen is set to 50 sccm; the radio frequency power is set to 200 W, the radio frequency frequency is set to 13.56 MHz, the temperature in the chamber is set to 300°C, and the pressure is set to 1 Torr;

[0048] (2) The reaction gas was introduced for 237 seconds until the reaction was complete.

[0049] Test Example 1

[0050] In the above-mentioned embodiments 1 to 3 and comparative examples 1 and 2, the tail gas is collected during the cleaning process, and a mass spectrometer is used to detect whether there are SiF-type ions. When the tail gas does not contain SiF-type ions, it indicates that the reaction is complete, and the cleaning gas is stopped from entering the chamber.

[0051] Examples 1 to 3 and Comparative Examples 1 and 2 clean the chamber after the same coating operation. The cleaning efficiency of different methods (cleaning efficiency = film thickness / reaction gas introduction time) is as follows: Figure 2 As shown, the cleaning method described in Example 1 can be used to quickly clean the chamber, greatly shorten the cleaning time, and effectively reduce the amount of cleaning gas used.

[0052] Test Example 2

[0053] The present invention further verifies the utilization rate of different fluorine-containing cleaning gases in the above-mentioned embodiments and comparative examples. The specific operation is as follows: the experimental operation is basically the same as the corresponding embodiments or comparative examples, but when the reaction gas is introduced, the RF power source is first turned off for 120 seconds, the exhaust gas is collected and the concentration of the fluorocarbon gas in the exhaust gas is calculated; then the RF power source is turned on for 120 seconds, the exhaust gas is collected and the concentration of the fluorocarbon gas in the exhaust gas is calculated.

[0054] Utilization rate of fluorine-containing cleaning gas A = (A RF power source off - A RF power source on) / A RF power source off × 100%

[0055] Among them, A RF power source turned off refers to the concentration of carbon fluorocompound gas in the exhaust gas of the fluorine-containing cleaning gas when the RF power source is turned off; A RF power source turned on refers to the concentration of carbon fluorocompound gas in the exhaust gas of the fluorine-containing cleaning gas when the RF power source is turned on.

[0056] In addition, the proportion of byproduct CF4 in the exhaust gas after turning on the RF power source in the above experiment was calculated.

[0057] The above experiment was repeated three times to obtain the range value. The test and calculation results are shown in Table 1 below:

[0058] Table 1 Utilization rate of cleaning gas and proportion of by-product CF4 in different cleaning methods

[0059]

[0060]

[0061] As shown in Table 1, compared with using NF3 or C2F6 as the cleaning gas, the utilization rate of octafluorocyclobutane as the fluorine-containing cleaning gas is higher, and the generation of the byproduct CF4 can be effectively reduced. In addition, from the utilization rate of the fluorine-containing cleaning gas and the amount of byproduct CF4 generated in the different cleaning methods of Examples 1 to 3, it can be seen that the present invention improves the utilization rate of the fluorine-containing cleaning gas and reduces the generation of the byproduct CF4 to a certain extent through argon plasma ignition and the introduction of nitrogen into the reaction gas, thereby reducing the demand for fluorine-containing cleaning gas and the cost of tail gas treatment during the cleaning process.

[0062] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A cleaning method for a semiconductor coating process chamber, characterized in that: The cleaning method comprises the following steps: (1) introducing argon gas into the process chamber, and turning on the RF power source to apply RF energy into the process chamber to excite the argon gas into plasma; (2) Under continuous application of radio frequency energy, a reaction gas is introduced into the process chamber to react with the byproducts remaining in the coating film in the chamber, and argon gas is continuously introduced while the reaction gas is introduced; the reaction gas comprises octafluorocyclobutane, nitrous oxide and nitrogen; the byproducts comprise SiO2, Si3N4 or SiO x N y One or more of , x, y>0; the flow rate of the octafluorocyclobutane is 4-15 sccm, the flow rate of the nitrous oxide is 5-50 sccm, the flow rate of the nitrogen is 300-800 sccm, and the flow rate of the argon is 100-200 sccm; (3) After the reaction is completed, nitrogen is introduced into the process chamber to remove the remaining dirt in the chamber.

2. The cleaning method according to claim 1, characterized in that: In step (1), the flow rate of argon gas is 100-200 sccm, and the time is 2-8 s.

3. The cleaning method according to claim 1, characterized in that: In step (2), the time for introducing octafluorocyclobutane is 50 to 300 s.

4. The cleaning method according to claim 1, characterized in that: In step (2), the time for introducing nitrous oxide is 50 to 300 seconds.

5. The cleaning method according to claim 1, characterized in that: In step (2), the time for introducing nitrogen is 50 to 300 seconds.

6. The cleaning method according to claim 1, characterized in that: In step (2), the time of the argon gas is 50 to 300 seconds.

7. The cleaning method according to claim 1, characterized in that: In step (3), the flow rate of nitrogen gas is 300-1000 sccm, and the time is 10-20 s.

8. The cleaning method according to claim 1, characterized in that: The radio frequency power is 20-200 W and the frequency is 13.56 MHz.

9. The cleaning method according to claim 1, characterized in that: During the cleaning process, a constant temperature and pressure are maintained in the process chamber; the temperature of the process chamber is 200-350°C, and the pressure is 1-3 Torr.

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