Aashing-cleaning method for cleaning etching chamber and inductively coupled plasma etching method

Abstract

The invention belongs to the technical field of semiconductor manufacturing, and particularly relates to an ashing-cleaning method for cleaning an etching chamber and an inductively coupled plasma etching method. According to the invention, first oxygen-containing mixed gas is ionized and then first cleaning is carried out on an etching chamber, wherein the first oxygen-containing mixed gas comprises fluorine-based gas; performing second cleaning on the etching chamber after second oxygen-containing mixed gas ionization; and performing third cleaning on the etching chamber after third oxygen-containing mixed gas ionization. According to the invention, step-by-step cleaning is carried out, and the cleanliness of the chamber can be obviously improved. The MTBC of the etching process cavity is effectively enhanced, the consistency of the environment of the etching cavity for etching different wafers and the consistency of the process parameters such as the etching rate, the etching thickness and the etching time in each part of the wafer during etching are ensured, and the situation that the subsequent process debugging and product stability are influenced due to the abnormal condition of the etching process caused by the change of the cavity environment is avoided. And the utilization rate of the etching machine is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to an ashing-cleaning method for cleaning an etching chamber and an inductively coupled plasma etching method. Background Art

[0002] The etching process is a very important link in the field of semiconductor manufacturing. The etching process often uses inductively coupled plasma etching (ICP) equipment. A large number of reaction by-products will be generated during the etching process. For example, non-volatile by-products such as smear will be deposited on the substrate and side walls of the process chamber. As the number of etched wafers increases, the deposits on the inner wall of the process chamber will continue to accumulate. During the etching process, slag will occur, resulting in poor product appearance, and even affecting the etching rate and the uniformity between and within the etched wafers, and the equipment cannot work normally. In response to the above phenomenon, under normal circumstances, it is necessary to perform open-cavity wet cleaning maintenance before normal etching operations. However, open-cavity wet cleaning maintenance is time-consuming and also shortens the periodic maintenance interval (MTBC) of the equipment, affecting the normal operating time of the equipment.

[0003] In order to reduce the frequency of cavity maintenance and ensure the quality of etching products, each wafer needs to be cleaned before etching. The Clean process mainly uses argon and oxygen. Oxygen ions are used to react with the hardened glue residue. Argon ions increase physical bombardment and assist plasma ignition. The basic components of the glue residue are organic substances such as C, H, and O. Under the action of the RF power supply, it reacts with oxygen ions to generate gas that is pumped away.

[0004] However, the traditional Clean process has poor cleaning effect, and the cavity frequently sheds residue, which seriously affects the product yield. The cavity needs to be opened for wet maintenance, which leads to frequent cavity maintenance. Summary of the invention

[0005] The object of the present invention is to provide an ash-clean method for cleaning an etching chamber and an inductively coupled plasma etching method. The method provided by the present invention can effectively remove etching by-products and avoid frequent slagging of the cavity in a short period of time, so that the cavity can be opened for wet maintenance after a long period of operation, effectively reducing the cavity opening frequency and effectively extending the MTBC of the etching process chamber.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides an ashing-cleaning method for cleaning an etching chamber, comprising the following steps:

[0008] (1) performing a first cleaning of the etching chamber after ionization with a first oxygen-containing mixed gas, wherein the first oxygen-containing mixed gas includes a fluorine-based gas, and the conditions for the first cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 1000 W or more higher than a power of the lower electrode;

[0009] (2) performing a second cleaning of the etching chamber after ionization with a second oxygen-containing mixed gas, wherein the conditions of the second cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 700 to 940 W higher than a power of the lower electrode;

[0010] (3) performing a third cleaning on the etching chamber after ionization with a third oxygen-containing mixed gas, wherein the conditions for the third cleaning include: a chamber pressure ≤ 50 mToor, and a power of the upper electrode 700 to 940 W higher than a power of the lower electrode;

[0011] There is no time limit for step (1), step (2) and step (3).

[0012] Preferably, the fluorine-based gas is CF4, the first oxygen-containing mixed gas includes an inert gas, oxygen and CF4, and the volume flow ratio of the inert gas, oxygen and CF4 is 1:(0.5-2):(0.5-2).

[0013] Preferably, the first cleaning conditions include: the chamber pressure is 80-100 mToor, the power of the upper electrode is 1000-1200 W, and the power of the lower electrode is 0 W.

[0014] Preferably, the second oxygen-containing mixed gas includes an inert gas and oxygen, and the volume flow ratio of the inert gas to oxygen is (1-3): (1-3).

[0015] Preferably, the second cleaning conditions include: the chamber pressure is 80-100 mToor, the power of the upper electrode is 800-1000 W, and the power of the lower electrode is 60-100 W.

[0016] Preferably, the third oxygen-containing mixed gas includes an inert gas and oxygen, and the volume flow ratio of the inert gas to oxygen is (1-3): (1-3).

[0017] Preferably, the conditions for the third cleaning include: a chamber pressure of 20 to 50 mToor, a power of the upper electrode of 800 to 1000 W, and a power of the lower electrode of 60 to 100 W.

[0018] Preferably, the time for the first cleaning, the second cleaning and the third cleaning is independently 10 to 20 minutes.

[0019] Preferably, step (1), step (2) and step (3) are performed sequentially.

[0020] The present invention provides an inductively coupled plasma etching method, comprising sequentially performing: formal wafer loading, etching, formal wafer unloading, bare chip loading, cleaning, and bare chip unloading;

[0021] The cleaning is performed by the ashing-cleaning method described in the above technical solution.

[0022] The present invention provides an ash-cleaning method for cleaning an etching chamber, comprising the following steps: (1) performing a first cleaning of the etching chamber after ionization with a first oxygen-containing mixed gas, wherein the first oxygen-containing mixed gas comprises a fluorine-based gas, and the conditions for the first cleaning comprise: a chamber pressure ≥ 80 mToor, and the power of an upper electrode is higher than the power of a lower electrode by more than 1000 W; (2) performing a second cleaning of the etching chamber after ionization with a second oxygen-containing mixed gas, and the conditions for the second cleaning comprise: a chamber pressure ≥ 80 mToor, and the power of an upper electrode is higher than the power of a lower electrode by 700 to 940 W; (3) performing a third cleaning of the etching chamber after ionization with a third oxygen-containing mixed gas, and the conditions for the third cleaning comprise: a chamber pressure ≤ 50 mToor, and the power of an upper electrode is higher than the power of a lower electrode by 700 to 940 W; steps (1), (2) and (3) are not limited in time sequence. The present invention adopts three steps to clean the etching chamber, and by controlling the chamber pressure and the power of the upper and lower electrodes, it can be achieved that: the plasma after ionization in step (1) is located in the upper area of ​​the etching chamber, and mainly cleans the upper substrate of the etching chamber. At the same time, the first oxygen-containing mixed gas used in step (1) includes a fluorine-based gas, which has a strong oxidizing property and can be ionized into a highly active ion group. In a chemical reaction, it reacts with a carbon chain to form a volatile carbon fluoride compound, which can quickly remove carbon atoms in the slag, so that after mixing with O2 and ionization, it can more effectively remove organic matter in the slag on the upper substrate, and can significantly improve the cleaning rate. The plasma after ionization in step (2) is located in the middle area of ​​the etching chamber, and mainly cleans the inner side wall of the chamber; the plasma after ionization in step (3) is located in the lower area of ​​the etching chamber, and mainly cleans the lower part of the inner side wall of the chamber, the focusing ring, the electrostatic chuck, and the fine gap formed at the connection between the electrostatic chuck and the focusing ring (byproducts are easily accumulated in the fine gap). The method provided by the present invention performs targeted cleaning of the upper area, middle area and lower area of ​​the etching chamber in steps and areas, and at the same time, the first oxygen-containing mixed gas containing fluorine-based gas is used for enhanced cleaning of the upper substrate with serious slag, thereby enhancing the cleaning effect. Therefore, the method provided by the present invention can effectively remove etching by-products, and can avoid frequent slag falling from the cavity in a short period of time, so that the cavity can be opened for wet maintenance after a long period of operation, effectively reducing the cavity opening frequency, and effectively extending the MTBC of the etching process cavity, thereby ensuring that the environment of the etching chamber for etching different wafers is consistent, and the consistency of process parameters such as etching rate, etching thickness and etching time at various locations in the wafer during etching, avoiding abnormal conditions in the etching process due to changes in the cavity environment, affecting subsequent process debugging and product stability, and significantly improving the utilization rate of the etching machine.

[0023] It can be seen from the results of the embodiment that by counting the number of etched wafers and the number of cavity cleaning times and monitoring the product etching rate, it is determined that the ashing-cleaning method provided by the present invention can effectively remove etching by-products, and cavity wet maintenance can be performed after operating 100 wafers, effectively reducing the number of cavity openings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a trend chart of silicon etching rate of the Clean process in Comparative Example 1;

[0025] Figure 2 This is a trend diagram of the silicon etching rate of the Ashing-Clean process in Example 2;

[0026] Figure 3 The Ashing-Clean process flow chart in the embodiment;

[0027] Figure 4 Schematic diagram of the cleaning position of the Ashing-Clean process step (1) in Example 1;

[0028] Figure 5 Schematic diagram of the cleaning position in the Ashing-Clean process step (2) in Example 1;

[0029] Figure 6 Schematic diagram of the cleaning position in the Ashing-Clean process step (3) in Example 1;

[0030] In the figure: 1 is the mixed gas inlet, 2 is the upper RF power supply, 3 is the pump, 4 is the lower RF power supply, 5 is the cooling gas inlet, 6 is the three needles, 7 is the focusing ring, 8 is the electrostatic chuck, and 9 is the plasma. DETAILED DESCRIPTION

[0031] The present invention provides an ashing-cleaning method for cleaning an etching chamber, comprising the following steps:

[0032] (1) performing a first cleaning of the etching chamber after ionization with a first oxygen-containing mixed gas, wherein the first oxygen-containing mixed gas includes a fluorine-based gas, and the conditions for the first cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 1000 W or more higher than a power of the lower electrode;

[0033] (2) performing a second cleaning of the etching chamber after ionization with a second oxygen-containing mixed gas, wherein the conditions of the second cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 700 to 940 W higher than a power of the lower electrode;

[0034] (3) performing a third cleaning on the etching chamber after ionization with a third oxygen-containing mixed gas, wherein the conditions for the third cleaning include: a chamber pressure ≤ 50 mToor, and a power of the upper electrode 700 to 940 W higher than a power of the lower electrode;

[0035] There is no time limit for step (1), step (2) and step (3).

[0036] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0037] The present invention uses a first oxygen-containing mixed gas to ionize and then perform a first cleaning on the etching chamber. The first oxygen-containing mixed gas includes a fluorine-based gas, and the fluorine-based gas is preferably CF4. The conditions for the first cleaning include: the chamber pressure is ≥80mToor, and the power of the upper electrode is more than 1000W higher than the power of the lower electrode. In the present invention, the first oxygen-containing mixed gas is a mixed gas containing oxygen. The first oxygen-containing mixed gas preferably includes an inert gas, oxygen and CF4. The inert gas is preferably argon. The volume flow ratio of the inert gas, oxygen and CF4 is preferably 1:(0.5~2):(0.5~2), more preferably 1:(1~2):(1~2), and in the embodiment it can be 1:2:2. The conditions for the first cleaning preferably include: the chamber pressure is preferably 80~100mToor, and in the embodiment it can be 80mToor, 85mToor, 90mToor, 95mToor or 100mToor. The upper electrode (i.e. Figures 4 to 6 The power of the middle and upper RF power source is preferably 1000-1200W, and in the embodiment, it can be 1000W, 1100W or 1200W. Figures 4 to 6 The power of the middle and lower RF power supply is preferably 0W. The time for the first cleaning is preferably 10 to 20 minutes, and in the embodiment it can be 10 minutes, 15 minutes or 20 minutes. In the present invention, during the first cleaning, the first oxygen-containing mixed gas enters the etching chamber through the mixed gas inlet 1. During the first cleaning process, the present invention preferably also includes: introducing cooling gas into the etching chamber through the cooling gas inlet 5, the cooling gas is used to cool the bare chip placed on the electrostatic chuck, and the cooling gas is preferably helium.

[0038] The present invention uses a second oxygen-containing mixed gas to ionize the etching chamber for a second cleaning, and the conditions for the second cleaning include: the chamber pressure ≥ 80mToor, and the power of the upper electrode is 700-940W higher than the power of the lower electrode. In the present invention, the second oxygen-containing mixed gas is a mixed gas containing oxygen. The second oxygen-containing mixed gas preferably includes an inert gas and oxygen. The inert gas is preferably argon. The volume flow ratio of the inert gas and oxygen is preferably (1-3): (1-3), more preferably (1-2): (1-2), and in the embodiment it can be 1:1. The conditions for the second cleaning preferably include: the chamber pressure is preferably 80-100mToor, and in the embodiment it can be 80mToor, 85mToor, 90mToor, 95mToor or 100mToor. The upper electrode (i.e. Figures 4 to 6 The power of the middle and upper RF power source is preferably 800-1000W, and in the embodiment, it can be 800W, 850W, 900W, 950W or 1000W. Figures 4 to 6 The power of the middle and lower RF power supply is preferably 60-100W, and in the embodiment it can be 60W, 70W, 80W, 90W or 100W. The time of the second cleaning is preferably 10-20min, and in the embodiment it can be 10min, 15min or 20min. In the present invention, during the second cleaning, the second oxygen-containing mixed gas enters the etching chamber through the mixed gas inlet 1. During the second cleaning process, the present invention preferably also includes: introducing cooling gas into the etching chamber through the cooling gas inlet 5, and the cooling gas is used to cool the bare chip placed on the electrostatic chuck, and the cooling gas is preferably helium.

[0039] The present invention uses a third oxygen-containing mixed gas to ionize the etching chamber for a third cleaning, and the conditions for the third cleaning include: the chamber pressure is ≤80mToor, and the power of the upper electrode is 700-940W higher than the power of the lower electrode. In the present invention, the third oxygen-containing mixed gas is a mixed gas containing oxygen. The third oxygen-containing mixed gas preferably includes an inert gas and oxygen. The inert gas is preferably argon. The volume flow ratio of the inert gas and oxygen is preferably (1-3): (1-3), more preferably (1-2): (1-2), and in the embodiment it can be 1:1. The conditions for the third cleaning preferably include: the chamber pressure is preferably 20-50mToor, and in the embodiment it can be 20mToor, 30mToor, 40mToor, 45mToor or 50mToor. The upper electrode (i.e. Figures 4 to 6 The power of the middle and upper RF power source is preferably 800-1000W, and in the embodiment, it can be 800W, 850W, 900W, 950W or 1000W. Figures 4 to 6The power of the middle and lower RF power supply is preferably 60 to 100 W, and in the embodiment it can be 60 W, 70 W, 80 W, 90 W or 100 W. The time of the third cleaning is preferably 10 to 20 minutes, and in the embodiment it can be 10 minutes, 15 minutes or 20 minutes. In the present invention, during the third cleaning, the third oxygen-containing mixed gas enters the etching chamber through the mixed gas inlet 1. During the third cleaning process, the present invention preferably also includes: introducing cooling gas into the etching chamber through the cooling gas inlet 5, and the cooling gas is used to cool the bare chip placed on the electrostatic chuck, and the cooling gas is preferably helium. The present invention has no special requirements for the volume flow rate of the cooling gas, and it is sufficient to ensure that the bare chip can be effectively cooled in the first cleaning, the second cleaning and the third cleaning.

[0040] The present invention has no limitation on the time sequence of the first cleaning, the second cleaning and the third cleaning. In an embodiment of the present invention, the first cleaning, the second cleaning and the third cleaning are performed sequentially.

[0041] The present invention can significantly improve the cleanliness of the chamber by performing step-by-step cleaning of different parts of the etching chamber by changing the power of the upper and lower electrodes and the chamber pressure. It effectively enhances the MTBC of the etching process chamber, ensures the consistency of the environment of the etching chamber for etching different wafers, and the consistency of process parameters such as etching rate, etching thickness and etching time at various locations in the wafer during etching, so as to avoid abnormal conditions in the etching process caused by changes in the chamber environment, which affects subsequent process debugging and product stability.

[0042] The present invention provides an inductively coupled plasma etching method, comprising sequentially performing: formal wafer loading, etching, formal wafer unloading, bare chip loading, cleaning, and bare chip unloading;

[0043] The cleaning is performed by the ashing-cleaning method described in the above technical solution.

[0044] In the present invention, the real wafer is a wafer with a photoresist coated on the surface. The bare chip is a wafer without a photoresist coated on the surface. The bare chip is used to protect the electrostatic chuck during the cleaning process.

[0045] In the present invention, the inductively coupled plasma etching is performed continuously, and the continuous operation includes sequentially performing etching unit operations, and the etching unit operations include sequentially performing: formal wafer loading, etching, formal wafer unloading, bare chip loading, cleaning, and bare chip unloading; the cleaning is performed using the ashing-cleaning method described in the above technical solution.

[0046] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0047] In the following embodiments, Figure 3 The ashing-cleaning method is carried out according to the flow chart.

[0048] Example 1

[0049] This embodiment provides an ashing-cleaning method for cleaning an etching chamber, comprising the following steps:

[0050] (1) The chamber pressure was set to 80 mToor, the upper electrode power (SrcRFPower, SRF) was adjusted to 1000 W, the lower electrode power (BiasRFPower, BRF) was adjusted to 0 W, and the volume flow ratio of Ar, O2 and CF4 was 1:2:2, specifically 100 sccm, 200 sccm and 200 sccm, respectively, where O2, Ar and CF4 were Figure 4 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 20 minutes. During the cleaning process, CF4 is ionized into highly active ion groups. The plasma generated by ionization is located in the upper area of ​​the chamber (such as Figure 4 The plasma 9) in the chamber is mainly O2 and CF4 mixed and ionized to react chemically with organic matter in the slag to remove the slag. This step mainly cleans the upper substrate of the chamber.

[0051] (2) The chamber pressure was set to 85 mToor, the upper electrode power (SrcRFPower, SRF) was adjusted to 800 W, the lower electrode power (BiasRFPower, BRF) was adjusted to 60 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 5 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 20 minutes. During the cleaning process, the plasma generated by ionization is located in the middle area of ​​the chamber (such as Figure 5 The plasma in the chamber 9), this step mainly cleans the side walls of the chamber.

[0052] (3) The chamber pressure was set to 20 mToor, the upper electrode power (SrcRFPower, SRF) was adjusted to 800 W, the lower electrode power (BiasRFPower, BRF) was adjusted to 60 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 6 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 20 minutes. During the cleaning process, the plasma generated by ionization is located in the lower area of ​​the chamber (such as Figure 6 The plasma in the chamber 9) is mainly used to clean the lower side wall of the chamber, the focusing ring and the Chuck platform.

[0053] Example 2

[0054] The present embodiment provides an inductively coupled plasma etching method, comprising sequentially performing: formal wafer loading, etching, formal wafer unloading, bare die loading, cleaning, and bare die unloading; wherein, cleaning is performed using the ashing-cleaning method provided in Embodiment 1.

[0055] Test Example 1

[0056] For the 100 wafers continuously operated in Example 2, one wafer is taken out for monitoring after every 10 wafers are etched. Nine points of each wafer are taken out for measuring the thickness before and after etching using an optical thickness gauge, and the average etching rate is calculated. The etching rate trend graph is shown in FIG. Figure 2 As shown, the etching rate decreases after etching the 100th wafer. The presumable reason is that some etching by-products in the etching chamber are not completely removed, which consumes part of the plasma and causes a decrease in the etching rate of the bottom wafer.

[0057] Comparative Example 1

[0058] This comparative example provides an inductively coupled plasma etching method, which includes sequentially performing: formal wafer loading, etching, formal wafer unloading, bare chip loading, cleaning, and bare chip unloading; wherein, cleaning is performed using a conventional Clean cleaning method.

[0059] Among them, the conventional Clean cleaning method includes the following steps:

[0060] The chamber pressure was set to 80 mToor, the upper electrode power (SrcRFPower) was adjusted to 800 W, the lower electrode power (BiasRFPower) was adjusted to 60 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm respectively, where O2 and Ar were Figure 5 The mixed gas inlet 1 is introduced. The cleaning time is 20 minutes.

[0061] Test Example 2

[0062] For the 40 wafers in continuous operation of Comparative Example 1, one wafer was taken out every 5 wafers for rate monitoring. Nine points of each wafer were taken out to measure the thickness before and after etching using an optical thickness gauge, and the average etching rate was calculated. The trend chart of the etching rate of the Clean process is shown in the figure. Figure 1 As shown, Figure 1 As shown, the etching rate of the traditional Clean process in Comparative Example 1 dropped to 0.624 μm / min after 30 consecutive operations, and the cavity frequently shed slag, seriously affecting the product yield, requiring cavity opening for wet maintenance, resulting in frequent cavity opening maintenance.

[0063] It can be seen from the above embodiments and comparative examples that the present invention provides an ash-cleaning method for cleaning an etching chamber, which cleans the etching process chamber in steps by changing the cleaning gas and the chamber pressure, counts the number of etched wafers and the number of cavity cleaning times, monitors the product etching rate, and determines that this procedure can effectively remove etching by-products. This process can perform cavity wet maintenance after operating 100 wafers, effectively reducing the number of cavity openings.

[0064] Example 3

[0065] This embodiment provides an ashing-cleaning method for cleaning an etching chamber, comprising the following steps:

[0066] (1) The chamber pressure was set to 100 mToor, the upper electrode power (SrcRFPower) was adjusted to 1200 W, the lower electrode power (BiasRFPower) was adjusted to 0 W, and the volume flow ratio of Ar, O2 and CF4 was 1:2:2, specifically 100 sccm, 200 sccm and 200 sccm, respectively, where O2, Ar and CF4 were Figure 4 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 10 minutes. During the cleaning process, CF4 is ionized into highly active ion groups. The plasma generated by ionization is located in the upper area of ​​the chamber (such as Figure 4 The plasma 9) in the chamber is mainly O2 and CF4 mixed and ionized to react chemically with organic matter in the slag to remove the slag. This step mainly cleans the upper substrate of the chamber.

[0067] (2) The chamber pressure was set to 100 mToor, the upper electrode power (SrcRFPower) was adjusted to 1000 W, the lower electrode power (BiasRFPower) was adjusted to 100 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 5 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 10 minutes. During the cleaning process, the plasma generated by ionization is located in the middle area of ​​the chamber (such as Figure 5 The plasma in the chamber 9), this step mainly cleans the side walls of the chamber.

[0068] (3) The chamber pressure was set to 50 mToor, the upper electrode power (SrcRFPower) was adjusted to 1000 W, the lower electrode power (BiasRFPower) was adjusted to 100 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 6 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 10 minutes. During the cleaning process, the plasma generated by ionization is located in the lower area of ​​the chamber (such as Figure 6The plasma in the chamber 9) is mainly used to clean the lower side wall of the chamber, the focusing ring and the Chuck platform.

[0069] Example 4

[0070] This embodiment provides an ashing-cleaning method for cleaning an etching chamber, comprising the following steps:

[0071] (1) The chamber pressure was set to 90 mToor, the upper electrode power (SrcRFPower) was adjusted to 1100 W, the lower electrode power (BiasRFPower) was adjusted to 0 W, and the volume flow ratio of Ar, O2 and CF4 was 1:2:2, specifically 100 sccm, 200 sccm and 200 sccm, respectively, where O2, Ar and CF4 were Figure 4 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 15 minutes. During the cleaning process, CF4 is ionized into highly active ion groups. The plasma generated by ionization is located in the upper area of ​​the chamber (such as Figure 4 The plasma 9) in the chamber is mainly O2 and CF4 mixed and ionized to react chemically with organic matter in the slag to remove the slag. This step mainly cleans the upper substrate of the chamber.

[0072] (2) The chamber pressure was set to 80 mToor, the upper electrode power (SrcRFPower) was adjusted to 900 W, the lower electrode power (BiasRFPower) was adjusted to 80 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 5 The mixed gas inlet 1 is introduced into the chamber. The cleaning time is 15 minutes. During the cleaning process, the plasma generated by ionization is located in the middle area of ​​the chamber (such as Figure 5 The plasma in the chamber 9), this step mainly cleans the side walls of the chamber.

[0073] (3) The chamber pressure was set to 30 mToor, the upper electrode power (SrcRFPower) was adjusted to 900 W, the lower electrode power (BiasRFPower) was adjusted to 80 W, and the volume flow ratio of Ar and O2 was 1:1, specifically 200 sccm and 200 sccm, respectively, where O2 and Ar were Figure 6 The mixed gas inlet 1 is introduced. The cleaning time is 15 minutes. During the cleaning process, the plasma generated by ionization is located in the lower area of ​​the chamber (such as Figure 6 The plasma in the chamber 9) is mainly used to clean the lower side wall of the chamber, the focusing ring and the Chuck platform.

[0074] The cleaning methods provided in Example 3 and Example 4 were used to perform inductively coupled plasma etching continuously, and the results were similar to those in Example 2.

[0075] It can be seen from the above embodiments that the present invention can significantly improve the cleanliness of the chamber by changing the upper and lower electrode power and the chamber pressure to perform step-by-step cleaning on different parts of the process chamber, effectively enhance the MTBC of the etching process chamber, ensure the consistency of the environment of the etching chamber for etching different wafers, and ensure the consistency of process parameters such as etching rate, etching thickness and etching time at various locations in the wafer during etching, so as to avoid abnormal conditions in the etching process due to changes in the chamber environment, affecting subsequent process debugging and product stability.

[0076] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An ashing-cleaning method for cleaning an etching chamber, characterized in that: The following steps are involved: (1) performing a first cleaning of the etching chamber after ionization with a first oxygen-containing mixed gas, wherein the first oxygen-containing mixed gas includes a fluorine-based gas, and the conditions for the first cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 1000 W or more higher than a power of the lower electrode; (2) performing a second cleaning of the etching chamber after ionization with a second oxygen-containing mixed gas, wherein the conditions of the second cleaning include: a chamber pressure ≥ 80 mToor, and a power of the upper electrode is 700 to 940 W higher than a power of the lower electrode; (3) performing a third cleaning on the etching chamber after ionization with a third oxygen-containing mixed gas, wherein the conditions for the third cleaning include: a chamber pressure ≤ 50 mToor, and a power of the upper electrode 700 to 940 W higher than a power of the lower electrode; There is no time limit for step (1), step (2) and step (3).

2. The ashing-cleaning method according to claim 1, characterized in that: The fluorine-based gas is CF4, the first oxygen-containing mixed gas includes an inert gas, oxygen and CF4, and the volume flow ratio of the inert gas, oxygen and CF4 is 1:(0.5-2):(0.5-2).

3. The ashing-cleaning method according to claim 1 or 2, characterized in that: The conditions for the first cleaning include: the chamber pressure is 80-100 mToor, the power of the upper electrode is 1000-1200 W, and the power of the lower electrode is 0 W.

4. The ashing-cleaning method according to claim 1, characterized in that: The second oxygen-containing mixed gas includes an inert gas and oxygen, and the volume flow ratio of the inert gas to the oxygen is (1-3): (1-3).

5. The ashing-cleaning method according to claim 1 or 4, characterized in that: The conditions for the second cleaning include: a chamber pressure of 80-100 mToor, a power of the upper electrode of 800-1000 W, and a power of the lower electrode of 60-100 W.

6. The ashing-cleaning method according to claim 1, characterized in that: The third oxygen-containing mixed gas includes an inert gas and oxygen, and the volume flow ratio of the inert gas to the oxygen is (1-3): (1-3).

7. The ashing-cleaning method according to claim 1 or 6, characterized in that: The conditions for the third cleaning include: the chamber pressure is 20-50 mToor, the power of the upper electrode is 800-1000 W, and the power of the lower electrode is 60-100 W.

8. The ashing-cleaning method according to claim 1, characterized in that: The time for the first cleaning, the second cleaning and the third cleaning is independently 10 to 20 minutes.

9. The ashing-cleaning method according to claim 1, characterized in that: The steps (1), (2) and (3) are performed sequentially.

10. An inductively coupled plasma etching method, characterized in that: It includes the following steps: formal wafer loading, etching, formal wafer unloading, bare die loading, cleaning, bare die unloading; The cleaning is performed by the ashing-cleaning method according to any one of claims 1 to 9.

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