WO2024045389A1

WO2024045389A1 - Wafer etching method

Info

Publication number: WO2024045389A1
Application number: PCT/CN2022/135870
Authority: WO
Inventors: 鞠小晶; 叶联; 车东晨; 彭泰彦; 许开东
Original assignee: 江苏鲁汶仪器有限公司
Priority date: 2022-08-31
Filing date: 2022-12-01
Publication date: 2024-03-07
Also published as: CN117672843A

Abstract

A wafer etching method, comprising the following steps: S1, mounting a plasma flow control device between a wafer (302) and a gas inlet (202a) of a plasma reaction chamber (200) of a plasma etcher; S2, placing the wafer (302) on a wafer support table (301) of the plasma etcher; S3, setting an etching parameter, and introducing an etching gas into the plasma reaction chamber (200) of the plasma etcher to etch the wafer (302); and S4, monitoring an etching process by using an end point detection system, and performing etching end point grasping at a main etching stage and etching end point grasping at an over-etching stage, at the main etching stage, performing etching end point grasping by using an optical signal of a main etching film layer etching product, and at the over-etching stage, performing etching end point grasping by using an optical signal of a stop layer etching product. The etching uniformity can be improved, the problem of waste caused by the fact that the etching gas is directly suctioned away by a vacuum pump (503) can be mitigated, and the loss of the stop layer can be reduced to the minimum while complete etching of the main etching film layer is guaranteed.

Description

Wafer etching method

This application claims priority to the Chinese patent application filed with the China Patent Office on August 31, 2022, with the application number 202211068971.0 and the invention name "Wafer Etching Method", the entire content of which is incorporated into this application by reference.

Technical field

This application relates to the field of semiconductor production technology, especially a wafer etching method

Background technique

Plasma etching machines are used in the semiconductor industry. The basic principle is that under vacuum and low pressure, the RF generated by the ICP RF power supply is output to the annular coupling coil, and a certain proportion of mixed etching gas is coupled with glow discharge to generate high-density plasma. Under the action of RF radio frequency from the lower electrode, these plasmas bombard the wafer substrate. The chemical bonds of the semiconductors in the pattern area of the wafer substrate are broken, and generate volatile substances with the etching gas, which are separated from the substrate in the form of gas. The piece is removed from the vacuum line.

At present, the plasma distribution is uneven during the working process of the plasma etching machine, and the etching gas is dispersed throughout the plasma reaction chamber, resulting in poor etching uniformity of the wafer. Taking metal aluminum etching as an example, currently on the market The uniformity of metal aluminum etching machines is generally above 8%, which also causes part of the etching gas to be directly pumped away by the vacuum pump, resulting in unnecessary waste.

Therefore, how to improve the etching uniformity of the wafer is a technical problem that needs to be solved by those skilled in the art.

Contents of the invention

In order to solve the above technical problems, this application provides a wafer etching method, which includes the following steps:

S1. Install a plasma flow control device between the wafer support table of the plasma etching machine and the air inlet of the plasma reaction chamber of the plasma etching machine; the plasma flow control device includes an inlet close to the plasma reaction chamber. The first annular body of the gas port, the second annular body close to the exhaust port of the plasma reaction chamber and the annular connector connected between the first annular body and the second annular body, the annular connector, the first annular body The body and the second annular body together form a flow control chamber, the inner hole of the first annular body forms an inlet for plasma to enter the flow control chamber, and the annular connecting body is provided with a place for plasma to flow out. The outlet of the flow control chamber, the wafer is located within the projection area of the inner hole of the first annular body on the wafer support table, and is also located in the inner hole of the second annular body within the wafer Within the projection area on the support table;

S2. Place the wafer on the wafer support table of the plasma etching machine;

S3. Set the etching parameters, and introduce etching gas into the plasma reaction chamber of the plasma etching machine to etch the wafer; the etching parameters include: upper RF power of the plasma etching machine, plasma etching The lower RF power of the machine, the chiller temperature of the plasma etching machine, the chamber pressure of the plasma reaction chamber, the etching gas and its flow rate.

In one embodiment of the wafer etching method, after the plasma flow control device is installed, the outer circumference of the first annular body and the outer circumference of the second annular body are in contact with the cavity side of the plasma reaction chamber of the plasma etching machine. There is a gap between the wall or the lined side wall of the plasma reaction chamber of the plasma etcher.

In one embodiment of the wafer etching method, the surface material of the plasma flow control device can be aluminum oxide, yttrium oxide, hard oxygen, aluminum, etc.

In an embodiment of the wafer etching method, the wafer includes an AlN layer or a Sc _× AlN layer, and the film layer etched in the main etching stage is the AlN layer or the Sc _× AlN layer of the wafer.

In an embodiment of the wafer etching method, the etching gas is one or more mixtures of Cl ₂ , BCl ₃ , Ar, and N ₂ .

In one embodiment of the wafer etching method, the inner hole diameter range of the first annular body of the plasma flow control device is: 200mm≤D1≤260mm, and the outer diameter range of the second annular body is: 250mm≤D2≤350mm , the height dimension range of the ring connector is 20mm≤H≤70mm.

In one embodiment of the wafer etching method, the upper RF power range of the plasma etching machine is: 800W≤P1≤1500W, the lower RF power range is: 300W≤P2≤800W, and the cavity pressure range of the plasma reaction chamber It is: 5mTorr≤P≤20mTorr, the temperature range of the chiller is: 20℃≤T≤80℃, the etching gas flow range is: 100sccm≤L≤250sccm.

An implementation manner of the wafer etching method further includes the following steps:

S4. Use the end point detection system to monitor the etching process, and capture the etching end point in the main etching stage and the etching end point in the over-etching stage.

In one embodiment of the wafer etching method, both the main etching stage and the over-etching stage use the optical signal of the etching product of the main etching film layer to capture the etching end point.

In one embodiment of the wafer etching method, the main etching stage uses the optical signal of the etching product of the main etching film layer to capture the etching end point, and the over-etching stage uses the optical signal of the etching product of the stop layer to capture the etching end point. Etching end point grab.

In this application, before etching, a plasma flow control device is installed between the wafer and the air inlet of the plasma reaction chamber of the plasma etching machine. During etching, the etching gas first enters the plasma reaction through the air inlet. Inside the cavity, since the first annular body is arranged close to the air inlet of the plasma reaction chamber, most of the etching gas enters the inside of the flow control chamber from the inner hole of the first annular body. Since the wafer is located inside the first annular body, The hole is within the projection area of the wafer support table and the inner hole of the second annular body is within the projection area of the wafer support table. Therefore, the inner hole of the first annular body can concentrate the etching gas more densely on the opposite surface. In the area of the wafer, the plasma in the concentrated etching gas can fall on the wafer and etch the wafer at high density. At the same time, under the blocking effect of the cavity wall of the flow control chamber, the plasma will flow in the wafer. By staying on the circle for a longer time, it can fully participate in the etching, which can improve the uniformity of the etching and alleviate the problem of wastage caused by the etching gas being directly sucked away by the vacuum pump.

Description of drawings

Figure 1 is a flow chart of the wafer etching method provided by this application;

Figure 2 is a cross-sectional view of the plasma flow control device and the wafer installed in the plasma reaction chamber of the plasma etching machine;

Figure 3 is a three-dimensional cross-sectional view of part of the structure in Figure 2;

Figure 4 is an etching rate distribution diagram when using the wafer etching method provided by this application to etch the AlN layer of a wafer;

Figure 5 is a comparison of the film structure of a wafer before and after etching;

Figure 6 is a microscopic comparison of the Mo layer after etching the wafer shown in Figure 5 using two etching methods. A-center and A-edge in the figure are respectively after etching with a plasma flow control device. Cross-sectional micrographs of the center and edge areas of the wafer. B-center and B-edge in the figure are respectively the cross-sectional micrographs of the center and edge areas of the wafer after etching without a plasma flow control device.

Figure 7 is a comparison chart of the results of grabbing the etching end point using two grabbing methods during the process of etching the same wafer. A in the figure is the grabbing result corresponding to single signal grabbing, and B in the figure is dual signal grabbing. Get the corresponding crawl results.

The reference symbols are explained as follows:

101 first annular body, 102 second annular body, 103 annular connecting body, 103a connecting column, 103b outlet.

200 plasma reaction chamber, 201 chamber, 201a exhaust port, 201b support sleeve, 202 chamber cover, 202a air inlet, 203 lining;

301 wafer support table, 302 wafer, 303 wafer focusing ring;

401 bias electrode, 402 bias electrode cover, 403 bias RF power supply, 404 bias matching network;

501 guide cover, 502 pressure control valve, 503 vacuum pump;

600 shielding cover;

701 coupling coil, 702 excitation source radio frequency power supply, 703 excitation source matching network;

800 ceramic dielectric window;

901 nozzle, 902 gas source.

Detailed ways

During the working process of previous plasma etching machines, the plasma distribution was uneven, and the etching gas was dispersed throughout the plasma reaction chamber, resulting in poor etching uniformity of the wafer (taking metal aluminum Al etching as an example, the current market The uniformity of metal aluminum etching machines on the machine is generally above 8%), which also causes part of the etching gas to be directly pumped away by the vacuum pump, resulting in unnecessary waste.

To this end, this application provides a wafer etching method, which can improve the etching uniformity of the wafer and alleviate the waste caused by the etching gas being directly pumped away by the vacuum pump.

In order to enable those skilled in the art to better understand the technical solution of the present application, the wafer etching method provided by the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 and 2, in this embodiment, the wafer etching method includes at least steps S1, S2 and S3.

S1. Install a plasma flow control device between the wafer support table of the plasma etching machine and the air inlet 202a of the plasma reaction chamber 200 of the plasma etching machine.

As shown in FIG. 2 , the plasma etching machine includes a plasma reaction chamber 200 . The wafer support table 301 is disposed inside the plasma reaction chamber 200 .

The plasma reaction chamber 200 has a chamber body 201, a chamber cover 202 and an inner lining 203. The bottom wall of the cavity 201 is provided with an exhaust port 201a. The cavity cover 202 is provided with an air inlet 202a. The lining 203 is embedded inside the cavity 201 of the plasma reaction chamber 200. The bottom wall of the lining 203 divides the inside of the cavity 201 of the plasma reaction chamber 200 into two upper and lower chambers. The upper chamber and the lower chamber pass through The through holes (not shown in the figure) on the bottom wall of the lining 203 are connected. Of course, in some embodiments, the lining 203 may not be provided.

As shown in Figures 2 and 3, the plasma flow control device includes a first annular body 101, a second annular body 102 and an annular connecting body 103.

The first annular body 101, the second annular body 102 and the annular connecting body 103 are all arranged around the straight line A. The first annular body 101 and the second annular body 102 are spaced apart from each other along the straight line A, forming a space therebetween. The first annular body 101 and the second annular body 102 may adopt a plate-like structure to facilitate arrangement.

The annular connecting body 103 is located in the space between the first annular body 101 and the second annular body 102 and connects the first annular body 101 and the second annular body 102 . The annular connecting body 103, the first annular body 101 and the second annular body 102 together form a flow control chamber.

The inner hole of the first annular body 101 forms an inlet for plasma to enter the flow control chamber. The annular connector 103 is provided with an outlet 103b for plasma to flow out of the flow control chamber. In Figure 3, the annular connector 103 has a split structure and includes a plurality of connecting columns 103a. Each connecting column 103a is arranged at intervals around the straight line A. The outlet 103b is formed between adjacent connecting columns 103a. Of course, the annular connecting body 103 can also be provided as an integral structure.

After the plasma flow control device is installed, the first annular body 101 is close to the air inlet 202a of the plasma reaction chamber 200, and the second annular body 102 is close to the exhaust port 201a of the plasma reaction chamber 200, more precisely, close to the crystal. Round support platform 301.

Specifically, the surface material of the plasma flow control device can be aluminum oxide, yttrium oxide, hard oxygen, aluminum, etc.

S2. Place the wafer 302 on the wafer support table 301 of the plasma etching machine.

After being placed, the wafer 302 is located between the air inlet 202a and the exhaust port 201a of the plasma reaction chamber 200, and is located within the projection area of the inner hole of the first annular body 101 on the wafer support table 301, and is also located The inner hole of the second annular body 102 is within the projection area on the wafer support table 301 .

S3. Set the etching parameters, and introduce the etching gas into the plasma reaction chamber 200 of the plasma etching machine to etch the wafer 302.

Specifically, the etching parameters include: upper RF power of the plasma etching machine, lower RF power of the plasma etching machine, chiller temperature of the plasma etching machine, chamber pressure of the plasma reaction chamber 200, etching gas and its flow rate. wait.

In the above wafer etching method, since before etching, a plasma flow control device is installed between the wafer 302 and the air inlet 202a of the plasma reaction chamber 200 of the plasma etching machine. In this way, when etching, , the etching gas first enters the inside of the plasma reaction chamber 200 from the air inlet 202a. Since the first annular body 101 is arranged close to the air inlet 202a of the plasma reaction chamber 200, most of the etching gas flows from the first annular body 101 The inner hole of the second annular body 102 enters the flow control chamber, and the plasma in the etching gas falls on the wafer through the inner hole of the second annular body 102 to etch the wafer, and then this part of the etching gas passes through the annular connector 103 The outflow port 103b is discharged from the flow control chamber, and then discharged from the exhaust port 201a of the plasma reaction chamber 200.

And since the wafer 302 is located within the projection area of the inner hole of the first annular body 101 on the wafer support table 301 and the inner hole of the second annular body 102 is within the projection area of the wafer support base 301, the first annular shape is The inner hole of the body 101 can concentrate the etching gas more densely in the area facing the wafer, and the plasma in the concentrated etching gas can fall concentratedly on the wafer, etching the wafer with high density. At the same time, under the blocking effect of the cavity wall of the flow control chamber, the plasma will stay on the wafer for a long time, so that it can fully participate in the etching. Therefore, it can improve the etching uniformity and alleviate the etching gas from being directly sucked away by the pump. Problems that lead to waste.

Specifically, in the illustrated embodiment, the plasma etching machine also includes a bias electrode 401, a bias electrode cover 402, a bias radio frequency power supply 403, and a bias matching network 404. The bias electrode 401, the bias matching network 404 and the bias radio frequency power supply 403 are connected in sequence through wires, and the bias electrode 401 provides the bias voltage required for etching.

It also includes a guide cover 501, a pressure control valve 502 and a vacuum pump 503. The inlet of the guide cover 501 is connected to the exhaust port 201a of the plasma reaction chamber 200, and the outlet of the guide cover 501 is connected to the pressure control valve 502. The pressure control valve 502 is connected to the vacuum pump 503. The vacuum pump 503 provides the negative pressure required for etching, and the pressure control valve 502 regulates the pressure.

A shield 600 is also included. The shielding cover 600 is fixed outside the plasma reaction chamber 200 and covers the air inlet 202a of the plasma reaction chamber 200. The shielding cover 600 and the plasma reaction chamber 200 are enclosed to form a shielding chamber.

It also includes a coupling coil 701, an excitation source RF power supply 702, and an excitation source matching network 703. The coupling coil 701, the excitation source matching network 703, and the excitation source RF power supply 702 are connected in turn through wires. Coupling coil 701 is placed in a shielded chamber.

Ceramic media window 800, nozzle 901, and gas source 902 are also included. The ceramic dielectric window 800 is disposed in the shielding chamber and is located between the coupling coil 701 and the air inlet 202a of the plasma reaction chamber 200. The nozzle 901 is disposed through the ceramic dielectric window 800 and communicates with the gas source 902 to inject the etching gas into the plasma reaction chamber. The etching gas is generated under the action of the coupling coil 701, etc.

Specifically, in the above wafer etching method, after the plasma flow control device is installed, it is preferable to align the outer periphery of the first annular body 101 and the outer periphery of the second annular body 102 with the side wall of the cavity 201 of the plasma reaction chamber 200 Or there is a gap between the side walls of the lining 203 of the plasma reaction chamber 200 . That is to say, when the plasma reaction chamber is not provided with the lining 203, a gap is formed between the outer periphery of the first annular body 101 and the second annular body 102 and the side wall of the cavity 201 of the plasma reaction chamber 200. When the plasma reaction chamber 200 is provided with the lining 203 , a gap is formed between the outer circumferences of the first annular body 101 and the second annular body 102 and the side walls of the lining 203 of the plasma reaction chamber 200 .

Let there be a gap between the outer circumference of the first annular body 101 and the outer circumference of the second annular body 102 and the side wall of the cavity 201 of the plasma reaction chamber 200 or the side wall of the lining 203 of the plasma reaction chamber 200. During the etching process, the particles It can fall from this gap, which can avoid particle accumulation and is more conducive to improving etching uniformity.

Specifically, by adjusting the inner hole size of the first annular body 101 of the plasma flow control device, the degree of concentration of the etching gas by the plasma flow control device can be changed. By adjusting the outer peripheral size of the second annular body 102 of the plasma flow control device, the residence time of the etching gas in the flow control chamber of the plasma flow control device can be changed. By adjusting the height dimension of the annular connector 103 of the plasma flow control device, the speed at which the etching gas is discharged from the flow control chamber can be changed. The degree of aggregation, residence time and discharge speed of etching gas can all have an impact on etching uniformity.

Preferably, when the film layer etched in the main etching stage is the AlN layer or Sc _X AlN layer of the wafer, the preferred range of the inner hole diameter of the first annular body of the plasma flow control device is: 200mm≤D1≤260mm, The preferred range of the outer diameter of the two-ring body is: 250mm≤D2≤350mm, and the preferred range of the height dimension of the annular connector (i.e., the size along the straight line A) is 20mm≤H≤70mm, which is more conducive to improving the etching uniformity.

Preferably, when the film layer etched in the main etching stage is the AlN layer or SC _X AlN layer of the wafer, the preferred range of the upper RF power of the plasma etching machine is: 800W≤P1≤1500W, and the preferred range of the lower RF power is: 300W≤P2≤800W, the preferred range of cavity pressure of plasma reaction chamber is: 5mTorr≤P≤20mTorr, the preferred range of chiller temperature is: 20℃≤T≤80℃, the preferred range of etching gas flow rate is: 100sccm≤L≤ 250sccm, which is more conducive to improving etching uniformity.

Specifically, when the film layer of the wafer etched in the main etching stage is an AlN layer or _SCxAlN layer, the etching gas can be one or more combinations of Cl ₂ , BCl ₃ , Ar, and N ₂ .

Specifically, Figure 4 shows the etching rate distribution diagram when the AlN layer of a wafer is etched using the above-mentioned wafer etching method. The substrate layer of the wafer is sequentially provided with an SiO ₂ insulation layer and an AlN layer. When etching the wafer, the inner hole diameter of the first annular body of the selected plasma flow control device is 230 mm, the outer diameter of the second annular body is 310 mm, and the height dimension of the annular connector is 30 mm. Set the upper RF power of the plasma etching machine to 1000W, the lower RF power to 500W, the cavity pressure of the plasma reaction chamber to 10mTorr, and the chiller temperature to 40°C. The etching gas is a mixture of BCl ₃ , Cl ₂ , and Ar. The flow rate of BCl ₃ is 45 sccm, the flow rate of Cl ₂ is 80 sccm, and the flow rate of Ar is 10 sccm. As shown in Figure 4, using the plasma flow control device of the above size and the above etching parameters, the etching uniformity can reach 2%.

Specifically, Figure 5 is a comparison of the film structure of a wafer before and after etching. The substrate layer of the wafer is sequentially provided with a SiO ₂ insulation layer, a Mo metal layer, and a SC _X AlN layer. When etching the wafer, the inner hole diameter of the first annular body of the selected plasma flow control device is 240 mm, the outer diameter of the second annular body is 300 mm, and the height dimension of the annular connector is 50 mm. Set the upper RF power of the plasma etching machine to 1500W, the lower RF power to 650W, the cavity pressure of the plasma reaction chamber to 12mTorr, and the chiller temperature to 50°C. The etching gas is a mixture of BCl ₃ , Cl ₂ , and N ₂ , in which the flow rate of BCl ₃ is 65 sccm, the flow rate of Cl ₂ is 60 sccm, and the flow rate of N ₂ is 10 sccm.

It can be seen from A-center and A-edge in Figure 6 that if a plasma flow control device is installed before etching, the loss in the center area of the wafer after etching is 33nm, the loss in the edge area is 66nm, and the uniformity is 8.8%.

It can be seen from B-center and B-edge in Figure 6 that without installing a plasma flow control device before etching, the loss in the center area of the wafer after etching is 40nm, and the loss in the edge area is 132nm. The uniformity is 26.7%.

From the comparison, it can be seen that adding the above-mentioned plasma flow control device can greatly improve the etching uniformity.

Further, as shown in Figure 1, the wafer etching method provided by this application may also include step S4.

S4. Use an endpoint detection system - such as an optical emission spectrometer (OES) to monitor the etching process, monitor the etching process, and capture the etching endpoint in the main etching stage and the etching endpoint in the over-etching stage. .

Specifically, in both the main etching stage and the over-etching stage, the optical signal of the etching product of the main etching film layer can be used to capture the etching end point, that is, single signal capture.

Alternatively, in the main etching stage, the optical signal of the etching product of the main etching film layer is used to capture the etching end point, and in the over-etching stage, the optical signal of the etching product of the stop layer is used to capture the etching end point, that is, dual signals. Grab.

Figure 7 is a comparison chart of the results of grabbing the etching end point using the above two grabbing methods during the process of etching the same wafer. A in the figure is the grabbing result corresponding to single signal grabbing, and B in the figure is dual signal. Fetch the corresponding fetch results.

The substrate layer of the wafer is sequentially provided with a SiO ₂ insulation layer, a Mo metal layer, and an AlN layer. When etching the wafer, the inner hole diameter of the first annular body of the selected plasma flow control device is 250 mm, the outer diameter of the second annular body is 300 mm, and the height dimension of the annular connector is 40 mm. Set the upper RF power of the plasma etching machine to 1200W, the lower RF power to 600W, the cavity pressure of the plasma reaction chamber to 12mTorr, and the chiller temperature to 50°C. The etching gas is a mixture of BCl ₃ , Cl ₂ , and N ₂ , in which the flow rate of BCl ₃ is 65 sccm, the flow rate of Cl ₂ is 60 sccm, and the flow rate of N ₂ is 10 sccm.

As shown in A in Figure 7, the capture results corresponding to the etching end point using single signal capture are: the main etching end point is 136.2S, the over-etching end point is 174.1S, and the over-etching amount is 27.8%.

As shown in B in Figure 7, the capture results corresponding to the etching endpoint using dual signals are: the main engraving endpoint is 136.2S, the overetching endpoint is 161.6S, and the overetching amount is 18.6%.

From the comparison, it can be seen that the over-etching amount is reduced by 9.2 percentage points when using dual signals to capture the etching end point than using a single signal to capture the etching end point. The use of dual signal capture to capture the etching end point is more accurate and is more conducive to reducing the amount of over-etching. It can ensure that the main etching film layer is completely etched while minimizing the loss of the stop layer.

In summary, one of the core ideas of this application is to install a plasma flow control device inside the plasma reaction chamber of the plasma etching machine before etching. By reasonably selecting the size of the plasma flow control device and reasonably setting the etching parameters, the Improve etching uniformity and reduce etching gas waste. Another core idea is: during the etching process, different signals are used in the main etching stage and the over-etching stage to accurately capture the etching end point. This can ensure that the main etching film layer is completely etched while also Stop layer losses are minimized.

The above uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and the core idea of the present application. It should be noted that, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

The wafer etching method is characterized by including the following steps:

S1. Install a plasma flow control device between the wafer support table of the plasma etching machine and the air inlet of the plasma reaction chamber of the plasma etching machine; the plasma flow control device includes an inlet close to the plasma reaction chamber. The first annular body of the gas port, the second annular body close to the exhaust port of the plasma reaction chamber and the annular connector connected between the first annular body and the second annular body, the annular connector, the first annular body The body and the second annular body together form a flow control chamber, the inner hole of the first annular body forms an inlet for plasma to enter the flow control chamber, and the annular connecting body is provided with a place for plasma to flow out. The outlet of the flow control chamber, the wafer is located within the projection area of the inner hole of the first annular body on the wafer support table, and is also located in the inner hole of the second annular body within the wafer Within the projection area on the support table;

S2. Place the wafer on the wafer support table of the plasma etching machine;

S3. Set etching parameters, and introduce etching gas into the plasma reaction chamber of the plasma etching machine to etch the wafer.
The wafer etching method according to claim 1, wherein the etching parameters include: upper RF power of the plasma etching machine, lower RF power of the plasma etching machine, and chiller temperature of the plasma etching machine. , the cavity pressure of the plasma reaction chamber, the etching gas and its flow rate.
The wafer etching method according to claim 2, characterized in that the plasma etching machine further includes a flow guide cover, a pressure control valve and a vacuum pump, and the inlet of the flow guide cover is connected with the exhaust port of the plasma reaction chamber. The outlet of the flow mask is connected to the pressure control valve, and the pressure control valve is connected to the vacuum pump. The vacuum pump provides the negative pressure required for etching, and the pressure control valve regulates the pressure.
The wafer etching method according to claim 1, characterized in that after the plasma flow control device is installed, the outer circumference of the first annular body and the outer circumference of the second annular body are in contact with the plasma of the plasma etching machine. There is a gap between the side wall of the reaction chamber or the lining side wall of the plasma reaction chamber of the plasma etching machine.
The wafer etching method according to claim 4, characterized in that the lining is embedded in the cavity of the plasma reaction chamber, and the bottom wall of the lining separates the cavity of the plasma reaction chamber into upper and lower parts. The upper chamber and the lower chamber are connected through the through hole on the inner substrate wall.
The wafer etching method according to claim 1, characterized in that after the plasma flow control device is installed, the first annular body is close to the air inlet of the plasma reaction chamber, and the second annular body is close to the wafer support. tower.
The wafer etching method according to claim 1, wherein the wafer placement area of the wafer support table is located between the air inlet and the exhaust port of the plasma reaction chamber. 7. The wafer etching method according to claim 1, wherein the surface material of the plasma flow control device is aluminum oxide, yttrium oxide, hard oxygen, or aluminum.
The wafer etching method according to claim 1, wherein the wafer includes an AlN layer or a Sc × AlN layer, and the film layer etched in the main etching stage is the AlN layer or the Sc × AlN layer of the wafer. .
The wafer etching method according to claim 8, wherein the etching gas is one or more mixtures of Cl 2 , BCl 3 , Ar, and N 2 .
The wafer etching method according to claim 8, characterized in that the inner hole diameter range of the first annular body of the plasma flow control device is: 200mm≤D1≤260mm, and the outer peripheral diameter range of the second annular body is: : 250mm≤D2≤350mm, the height dimension range of the ring connector is 20mm≤H≤70mm.
The wafer etching method according to claim 8, characterized in that the upper radio frequency power range of the plasma etching machine is: 800W≤P1≤1500W, the lower radio frequency power range is: 300W≤P2≤800W, and the plasma The cavity pressure range of the reaction chamber is: 5mTorr≤P≤20mTorr, the temperature range of the chiller is: 20℃≤T≤80℃, and the etching gas flow range is: 100sccm≤L≤250sccm.
The wafer etching method according to any one of claims 1 to 11, further comprising the following steps:

S4. Use the end point detection system to monitor the etching process, and capture the etching end point in the main etching stage and the etching end point in the over-etching stage.
The wafer etching method according to claim 12, characterized in that, in both the main etching stage and the over-etching stage, the optical signal of the etching product of the main etching film layer is used to capture the etching end point.
The wafer etching method according to claim 12, wherein the main etching stage uses the optical signal of the etching product of the main etching film layer to capture the etching end point, and the over-etching stage uses the etching of the stop layer to capture the etching end point. The optical signal of the etching product is used to capture the etching end point.
The wafer etching method according to any one of claims 1 to 11, wherein the plasma etching machine further includes a bias electrode, and the bias electrode provides the bias voltage required for etching.
The wafer etching method according to any one of claims 1 to 11, characterized in that the plasma etching machine further includes a shielding cover, which is fixed outside the plasma reaction chamber and covers the air inlet of the plasma reaction chamber. The mouth, shielding cover and plasma reaction chamber are enclosed to form a shielding chamber;

The plasma etching machine also includes a coupling coil, an excitation source radio frequency power supply, and an excitation source matching network. The coupling coil, the excitation source matching network, and the excitation source radio frequency power supply are connected in turn through wires. The coupling coil is arranged in a shielded chamber.
The wafer etching method according to claim 16, characterized in that the plasma etching machine further includes a ceramic dielectric window, a nozzle and a gas source, the ceramic dielectric window is arranged in the shielding chamber and is located between the coupling coil and the plasma reaction chamber. Between the air inlets, the nozzle penetrates the ceramic dielectric window and is connected to the gas source to inject process gas into the plasma reaction chamber. The process gas generates plasma under the action of the coupling coil.
The wafer etching method according to any one of claims 1 to 11, characterized in that, according to process conditions, by adjusting the inner hole size of the first annular body and/or adjusting the outer peripheral size of the second annular body, and/or, adjusting the height dimension of the annular connector to optimize the uniformity of the plasma etcher.
The wafer etching method according to any one of claims 1 to 11, wherein the outer circumferential size of the second annular body is smaller than the outer circumferential size of the first annular body.
The wafer etching method according to any one of claims 1 to 11, characterized in that both the first annular body and the second annular body are plate-shaped structures.