Etching method and plasma etching device

Abstract

The invention discloses an etching method and a plasma etching device.The etching method comprises the steps that a reaction cavity is provided, and a substrate is placed in the reaction cavity; an etching step: etching the substrate below 0 DEG C; a heating step: heating the substrate to 60 DEG C or above, and discharging by-products deposited on the substrate in a gaseous form; the etching step and the heating step are alternately carried out. According to the method, after etching is carried out for a period of time, the temperature of the substrate is raised to 60 DEG C or above, so that by-products originally adhered to the substrate are discharged from the substrate, and the etching efficiency is improved. The etching step and the heating step are alternately and circularly carried out, so that each etching step can keep a higher etching speed, and the advantages of low-temperature etching are fully exerted.

Description

Technical Field

[0001] The invention relates to the field of semiconductors, and in particular to an etching method and a plasma etching device. Background Art

[0002] With the development of semiconductor technology, the size of devices is getting smaller and smaller, and the stacking height is getting higher and higher. In order to etch a high aspect ratio recessed structure on the substrate, low temperature etching is usually used. Low temperature etching refers to the operation of etching in an environment with a temperature equal to or lower than 0°C, which can be used for silicon etching or dielectric etching. Under low temperature conditions, the adhesion coefficient of the etching gas is much higher than that at room temperature, and it is easier to deposit on the sidewalls and bottom of the recessed structure, promoting the etching process.

[0003] The etching time of low temperature etching usually exceeds 30 minutes. However, as the etching time continues, the thermal effect of the plasma will cause the substrate temperature to gradually rise, making it increasingly difficult for the etching gas to deposit, and the byproducts produced during the etching process gradually accumulate, hindering the etching gas from reacting with the target material in the recessed structure, reducing the etching efficiency. Summary of the invention

[0004] The object of the present invention is to provide an etching method with a fast etching speed so as to obtain a substrate with a recessed structure having a high aspect ratio and high collimation.

[0005] In order to achieve the above object, the present invention provides an etching method, comprising:

[0006] Providing a reaction chamber, wherein a substrate is placed in the reaction chamber;

[0007] Etching step: etching the substrate at a temperature below 0° C.;

[0008] Heating step: heating the substrate to above 60° C. so that the byproducts deposited on the substrate are discharged in a gaseous form;

[0009] The etching step and the heating step are performed alternately.

[0010] Optionally, a time ratio between the etching step and the heating step is greater than or equal to 1.

[0011] Optionally, the etching step takes longer than 300 s.

[0012] Optionally, the etching step takes less than 1800 seconds.

[0013] Optionally, the etching step includes: etching a recessed structure on the substrate, wherein the depth-to-width ratio of the recessed structure is greater than or equal to 40.

[0014] Optionally, the recessed structure is divided into n sections along the depth direction, and the total time of the etching step of the (k-1)th recessed structure is less than the total time of the etching step of the kth recessed structure; wherein n≥2, 2≤k≤n, and n and k are integers.

[0015] Optionally, the etching step and the heating step are alternately cycled at least 3 times.

[0016] Optionally, the temperature raising step includes: lifting the substrate so that the substrate is close to a gas shower head at the top of the reaction chamber, and the temperature of the substrate is raised to above 60° C.

[0017] Optionally, the temperature increasing step includes: providing a heating chamber, transferring the substrate into the heating chamber, and heating the substrate to above 60°C.

[0018] Optionally, the heating step includes: reducing the pressure of the heat-conducting gas on the back side of the substrate to heat the substrate to above 60°C.

[0019] Optionally, in the etching step, the etching gas introduced into the reaction chamber comprises:

[0020] C x F y , C x H y F z One or more of , wherein x is greater than or equal to 1, y is greater than or equal to 1, z is greater than or equal to 1, and x, y, and z are all positive integers.

[0021] Optionally, the etching gas further comprises: a halogen-containing gas, wherein the halogen-containing gas comprises HBr, HI, Br 2 or I 2 One or more of .

[0022] Optionally, the by-product consists of any one or more elements of Si, O, I, Br or F.

[0023] The present invention also provides a plasma etching device, comprising:

[0024] Reaction chamber;

[0025] A pedestal is provided in the reaction chamber, the substrate is placed on the pedestal, and a cooling device is provided in the pedestal for cooling the substrate so that the etching step is performed below 0° C.; and

[0026] A heating device is used to heat the substrate to above 60°C.

[0027] Optionally, the temperature increasing device comprises a gas shower head, and the gas shower head is located in the reaction chamber and arranged opposite to the base;

[0028] The base is provided with lifting pins for lifting the substrate so that the substrate is away from the base and close to the gas shower head, and the temperature of the substrate is raised to above 60°C.

[0029] Optionally, the temperature increasing device comprises a heating chamber, and the substrate is transferred from the reaction chamber to the heating chamber to increase the temperature of the substrate to above 60°C.

[0030] Optionally, the cooling device includes a cooling pipe arranged in the base, a refrigerant flows through the cooling pipe, and the bottom surface of the substrate is in contact with the refrigerant, so that the etching step is performed below 0°C.

[0031] Optionally, the temperature of the refrigerant is not higher than -60°C.

[0032] Optionally, a gas transmission channel is provided in the base, and the gas transmission channel is used to transmit heat-conducting gas to the gap between the substrate and the base.

[0033] The beneficial effects of the present invention are:

[0034] (1) After etching for a period of time, the present invention heats the substrate to above 60°C by providing an additional heat source to reach the escape temperature of the by-products, so that the by-products originally adhering to the substrate are discharged from the substrate, which is beneficial for the etching gas to fully contact with the substrate to be etched, thereby improving the etching efficiency.

[0035] (2) The etching step and the heating step of the present invention are carried out in an alternating cycle, and the long-term continuous etching is divided into multiple short-term etchings by intervening a heating heat treatment. In several etching steps spaced apart from each other, at the beginning of each etching step, the etching gas is collected again on the substrate surface for deposition and adsorption. Compared with continuous etching, each short-term etching step can maintain a faster etching speed, thereby giving full play to the advantages of low-temperature etching. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention provides a flow chart of the etching method.

[0037] Figure 2 This is a schematic structural diagram of the plasma etching device provided by the present invention.

[0038] Figure 3 Schematic diagram of the etching process according to an embodiment of the present invention.

[0039] Figure 4 FIG. 4 is a graph showing the change of substrate temperature over time according to an embodiment of the present invention.

[0040] Figure 5FIG. 4 is a graph showing the etching rate changing with time according to an embodiment of the present invention.

[0041] Figure 6 Schematic diagram of the etching process for a comparative example.

[0042] Figure 7 The graph of the substrate temperature of the comparative example changing with time.

[0043] Figure 8 This is a curve chart showing the etching rate of the comparative example changing with time.

[0044] Fig. 9 This is an electron microscope image of a substrate obtained according to an embodiment of the present invention.

[0045] Fig.10 This is an electron microscope image of the substrate obtained in the comparative example.

[0046] In the figure, 100 - reaction chamber, 110 - base, 120 - electrostatic chuck, 130 - gas shower head, 140 - cooling pipe, 200 - recessed structure, 210 - etching gas, W - substrate. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0049] like Figure 1 As shown, the present invention provides an etching method, comprising:

[0050] S1: providing a reaction chamber, wherein a substrate is placed in the reaction chamber.

[0051] A pedestal is arranged in the reaction chamber, the substrate is placed on the pedestal, a cooling device for cooling the substrate to below 0°C and a heating device for heating the substrate to 60°C are arranged in the pedestal.

[0052] S2: Etching step: etching the substrate at below 0°C.

[0053] The substrate is placed in a low-temperature environment below 0°C, and an etching gas is introduced. The etching gas has a high adhesion coefficient at low temperatures and is easily adsorbed and deposited on the surface of the substrate to form a thin film. When the concentration of the etching gas reaches the requirement, a radio frequency signal is provided to dissociate the etching gas into plasma, which is deposited and adsorbed on the surface of the substrate to be etched, reacts with the substrate to be etched, and etches the substrate.

[0054] The method provided by the present invention can be used to etch the stack of polysilicon and silicon oxide in 3D NAND, the stack of silicon oxide and silicon nitride, and the memory in DRAM, etc. The etching step comprises: etching a recessed structure on the substrate along a stacking direction perpendicular to each stacked layer, wherein the depth-to-width ratio of the recessed structure is greater than or equal to 40.

[0055] In some embodiments, the etching gas introduced into the reaction chamber comprises C x F y , C x H y F z One or more of, wherein x is greater than or equal to 1, y is greater than or equal to 1, z is greater than or equal to 1, and x, y, and z are all positive numbers. Also included: halogen-containing gas, the halogen-containing gas includes HBr, HI, Br 2 or I 2 One or more of .

[0056] S3: Heating step: heating the substrate to above 60° C. so that the by-products deposited on the substrate are discharged in a gaseous form.

[0057] As etching proceeds, the by-products accumulated on the substrate increase, hindering the contact between the etching gas and the substrate, thereby reducing the reaction rate between the etching gas and the material to be etched on the substrate surface. The by-products generated on the substrate are composed of any one or more elements of Si, O, I, Br or F. In normal temperature etching, the by-products are in gaseous state and can be discharged from the substrate in time. However, the temperature of low temperature etching is lower than that of normal temperature etching, and the adhesion coefficient of the by-products increases, making it easy to adhere to the substrate. In addition, when the deposited etching gas reaches a sufficiently high reaction concentration, it will ignite and dissociate. Therefore, in the initial stage of the etching step, the amount of etching gas deposited on the substrate is large, the two are in full contact, the reaction is fast, and the generation rate of by-products is also fast. Even if a small amount of by-products can be discharged from the substrate, the discharge rate of the by-products is much lower than the generation rate of the by-products, causing the by-products to gradually accumulate at the bottom and side walls of the recessed structure, hindering the contact between the etching gas and the substrate to be etched, causing the reaction rate to gradually decrease.

[0058] In order to improve the etching efficiency, the present invention raises the temperature of the substrate to above 60°C after the etching step is carried out for a period of time, so that the by-products are discharged from the surface of the substrate in the form of gas. Although the temperature of the substrate will increase due to the plasma thermal effect as the etching proceeds during the etching step, this temperature is not enough to reach the escape temperature of the by-products, and the substrate temperature still needs to be increased by providing an additional heat source.

[0059] Low-temperature etching requires that the temperature be kept below 0°C, but the heat generated by the ignition of the plasma cannot be dissipated in a short time, and as the etching step continues, the temperature of the substrate will always be maintained above 0°C. Therefore, the etching step and the heating step of the present invention are performed alternately. After the heating step is completed, the etching step is cycled again. By intervening in the heating step to heat-treat the substrate, the long-term continuous etching is divided into multiple short-term etchings. In the initial stage of each etching step, the substrate is placed in a low-temperature environment, and the etching gas can be deposited on the substrate again. Compared with continuous etching, the reactant concentration of each etching step is higher, the etching speed is faster, and the advantages of low-temperature etching are better utilized. Optionally, the etching step and the heating step are alternately cycled at least 3 times. When the last etching step is completed, the etching ends, and the heating step is no longer performed.

[0060] In some embodiments, the time ratio of the etching step to the heating step is greater than or equal to 1. Since the etching step and the heating step are performed alternately and cyclically, each cycle includes one etching step and one heating step. The time ratio of the etching step to the heating step is greater than or equal to 1 means that in any one cycle, the time ratio of the etching step to the heating step is greater than or equal to 1. Optionally, the time of the etching step is greater than 300s and less than 1800s.

[0061] In some other embodiments, the recessed structure is divided into n segments along the depth direction, and the total time of the etching step of the (k-1)th recessed structure is less than the total time of the etching step of the kth recessed structure; wherein n≥2, 2≤k≤n, and n and k are integers.

[0062] In the initial stage of the etching step, the concentration of the etching gas is the highest, the deposition amount on the substrate surface is the largest, the etching speed is the fastest, and a large amount of by-products will be generated in a short time. And when the time of each etching step is the same, the average etching speed of the previous etching step is greater than that of the next one, and the by-product generation rate of the previous etching step is greater than that of the next one. Etching is carried out from the substrate surface to the inside of the substrate along the stacking direction perpendicular to the stacking direction of each layer of the substrate. In this embodiment, the recessed structure is divided into n sections along the depth direction, and the (k-1) section recessed structure is formed before the k-th section recessed structure. That is to say, when etching the recessed structure of the same depth, the (k-1) section has a faster etching speed than the k-th section, and the by-products accumulate faster. In a shorter etching time, a heating step is required to discharge the by-products. Therefore, the present embodiment defines that: although etching each section of the recessed structure may include several alternating cycles of etching steps and heating steps, and the duration of the etching steps in each cycle is not completely consistent, no matter how the etching steps and heating steps are alternately cycled, the total etching time of the (k-1) section of the recessed structure is less than the total etching time of the k section of the recessed structure. The (k-1) section of the recessed structure has a fast etching speed and a fast accumulation speed of byproducts, so the etching time of this section is limited to be shorter, so that the byproducts do not accumulate too much and hinder the contact between the etching gas and the substrate; while the etching speed of etching the k section of the recessed structure is slower than that of the (k-1) section, and the accumulation speed of byproducts is also slower, at this time, the total etching time of the k section of the recessed structure is extended, and the alternating frequency of the etching steps and the heating steps is reduced to improve the etching efficiency.

[0063] In the heating step, the method of heating the substrate to above 60° C. includes at least the following:

[0064] (1) lifting the substrate so that the substrate is close to the gas shower head at the top of the reaction chamber. Since a heater is provided inside the gas shower head, the heat of the gas shower head is used to heat the substrate;

[0065] (2) providing a heating chamber, transferring the substrate into the heating chamber, heating the substrate, and then transferring the substrate from the heating chamber back into the reaction chamber for etching;

[0066] (3) The pressure of the helium gas on the back of the electrostatic chuck can affect the temperature of the substrate. The greater the pressure of the helium gas on the back, the better the cooling effect. The pressure of the heat-conducting gas on the back of the substrate can be reduced to increase the temperature of the substrate.

[0067] like Figure 2As shown, the present invention also provides a plasma etching device, comprising: a reaction chamber 100; a base 110 is provided in the reaction chamber 100, an electrostatic chuck 120 is included above the base 110, the substrate W is placed on the electrostatic chuck 120, a cooling device is provided in the base 110 for cooling the substrate so that the etching step is performed below 0°C; and a heating device for heating the substrate to above 60°C.

[0068] The base 110 is provided with a cooling pipe 140. In some embodiments, the cooling pipe 140 is used as a cooling device, and a refrigerant is introduced into the cooling pipe. The bottom surface of the substrate W contacts the refrigerant, so that the etching step is performed below 0°C. Optionally, the temperature of the refrigerant is not higher than -60°C.

[0069] For a capacitively coupled plasma (CCP) reaction device, a gas shower head 130 is arranged in the reaction chamber 100 and opposite to the susceptor. The gas shower head 130 is connected to a gas supply device and is used to deliver reaction gas into the reaction chamber 100. In some embodiments, the gas shower head 130 is used as a temperature increasing device, and a heater (not shown) is arranged inside the gas shower head 130. When performing the temperature increasing step, the lifting pins arranged on the susceptor 110 are used to lift the substrate W so that the substrate W is away from the susceptor 110 and close to the gas shower head 130. The heater inside the gas shower head 130 heats the gas shower head 130 so that the substrate W is heated to above 60°C. After the temperature increasing step is completed, the lifting pins are lowered, and the substrate W moves toward the susceptor 110 until the substrate W is placed on the susceptor 110, and the etching step is continued.

[0070] In some embodiments, the temperature increasing device includes a heating chamber independently provided from the reaction chamber 100. When performing the temperature increasing step, a robot is used to grab the substrate W, and the substrate W is moved from the reaction chamber 100 to the heating chamber, so that the temperature of the substrate W is increased to above 60°C. After the temperature increasing step is completed, the robot is used to move the substrate from the heating chamber to the reaction chamber 100, and the etching step is continued. By using the robot to transfer the substrate between the reaction chamber 100 and the heating chamber to perform the temperature increasing step, the substrate W can be accurately placed back to a specific position on the base 110, thereby ensuring the safety of the next etching step.

[0071] In some embodiments, a gas transmission channel is provided in the base 110, and the gas transmission channel is used to transmit a heat-conducting gas to the gap between the substrate W and the base 110. The heat-conducting gas may be helium or hydrogen. When performing the temperature raising step, the pressure of the heat-conducting gas on the back side of the substrate is reduced to raise the temperature of the substrate.

[0072] Example

[0073] This embodiment provides an etching method, including:

[0074] S1: Provide the same Figure 2 The reaction chamber shown has a substrate placed in it.

[0075] S2: Etching step: etching the substrate at below 0°C.

[0076] The substrate is placed in a low temperature environment below 0°C and a stream of CHF 3 , CH 2 F 2 , O 2 NF 3 and HBr, such as Figure 3 As shown in (a), the bottom and sidewalls of the recessed structure 200 are deposited with deposits 210 due to low temperature. At this time, the deposits 210 are mainly composed of etching gas, and the etching gas is dissociated into plasma to etch the substrate W.

[0077] S3: Heating step: heating the substrate to above 60° C. to discharge the by-products deposited on the substrate in a gaseous form.

[0078] like Figure 4 and Figure 5 As shown, as the etching proceeds, the main component of the deposit 210 deposited in the recessed structure 200 due to the low temperature gradually changes from the etching gas to the by-product. The newly introduced etching gas is not easy to be deposited on the surface of the substrate W due to the barrier of the by-product. The temperature rise caused by the plasma thermal effect alone is not enough to discharge the by-products generated in the etching step from the substrate. The by-products hinder the contact between the etching gas and the substrate W. Therefore, the etching speed gradually decreases. At this time, the substrate is heated to above 60°C. Figure 3 As shown in (b), the main component byproduct in the deposit 210 is gasified due to high temperature and discharged from the recessed structure 200. After a period of time, when the byproduct is discharged from the substrate, the substrate is placed in a low temperature environment again, and the substrate temperature drops sharply to the initial stage of the etching step. At this time, as shown in FIG. Figure 3 As shown in (c), the etching gas 210 will condense and deposit on the bottom and sidewalls of the recessed structure again. When the concentration of the etching gas reaches the required level, it will be ignited and dissociated, and the etching speed will be accelerated to continue etching the recessed structure downward until the concentration reaches the required level. Figure 3 (d) Target etch depth shown.

[0079] In this embodiment, the time of each etching step is 600s, the time of each heating step is 150s, and the etching step and the heating step are alternately cycled 3 times. When the third etching step is completed, the etching is finished. At this time, the morphology of the concave structure is as follows Figure 3 The etching process includes three etching steps and two heating steps, which takes a total of 2100 seconds.

[0080] Comparative Example

[0081] A substrate is placed on the base of the reaction chamber, and the substrate is placed in a low temperature environment below 0°C, and CHF 3 and HBr. Figure 6 As shown in (a), the etching gas is dissociated into plasma to etch the substrate W. The etching step continues until the etching is completed. At this time, the morphology of the recessed structure is as follows Figure 6 As shown in (b). Figure 7 and Figure 8 As shown, during the etching process, the temperature of the substrate gradually increases, and the deposits deposited in the recessed structure of the substrate gradually transform into byproducts, which hinder the entry of subsequent etching gases, resulting in a gradual decrease in the etching rate. In this example, the etching step lasts for 2100 seconds.

[0082] Table 1 Comparison of substrate properties obtained in the examples and comparative examples Unit: nm

[0083]

[0084]

[0085] Fig. 9 and Fig.10 They are substrates obtained in the embodiment and the comparative example respectively. The dimensions of the recessed structures of the two substrates are shown in Table 1. Among them, the maximum lateral dimension is the dimension at the maximum width of the recessed structure, the bottom dimension is the width of the bottom of the recessed structure, the maximum lateral dimension-bottom dimension represents the difference between the dimension at the maximum width of the recessed structure and the width of the bottom of the recessed structure, and the etching depth is the depth of the recessed structure.

[0086] The embodiment uses multiple intervention heating steps to cut the continuous etching process into multiple discontinuous etching steps. In the initial stage of each etching step, etching gas is deposited at the bottom of the recessed structure, so that the width of the recessed structure etched in each etching step tends to be consistent. In the continuous etching process of the comparative example, the amount of etching gas deposition at the bottom of the recessed structure is reduced, and the by-products hinder the contact between the etching gas and the substrate to be etched, making the bottom morphology of the recessed structure sharper. Compared with the comparative example, the embodiment has a smaller maximum lateral dimension, a wider bottom width, and a smaller difference between the dimension at the maximum width and the bottom width, indicating that the sidewalls of the recessed structure are closer to vertical and have high collimation.

[0087] The total etching time of the embodiment and the comparative example is the same, but because the etching process of the embodiment also includes a heating step, the actual etching time of the embodiment is shorter than that of the comparative example. According to Table 1, the etching depth of the embodiment is deeper than that of the comparative example, indicating that although the etching process of the embodiment sacrifices part of the etching time for heating, the etching step of the embodiment has a higher reactant concentration and etching rate, and the substrate obtained by the embodiment has a higher aspect ratio. Moreover, by further controlling the time ratio of the etching step and the heating step, the etching depth can be further increased. When the etching depth is basically the same, the substrate obtained by discontinuous multiple etching steps has a better morphology of the recessed structure than the substrate obtained by continuous etching.

[0088] In summary, the present invention provides an etching method, after etching for a period of time, by providing an additional heat source, the substrate is heated to above 60°C to reach the escape temperature of the by-products, so that the by-products originally adhering to the substrate are discharged from the substrate, and the etching gas can fully contact the surface of the substrate to be etched, so as to improve the etching efficiency. The etching step and the heating step of the present invention are alternately cyclically performed, and the long-term continuous etching is divided into multiple short-term etchings by intervening the heating heat treatment. Since the etching gas can be deposited on the substrate surface again in each etching step, compared with continuous etching, each short-term etching step can maintain a faster etching speed, giving full play to the advantages of low-temperature etching.

[0089] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. An etching method, characterized in that: include: Providing a reaction chamber, wherein a substrate is placed in the reaction chamber; Etching step: etching the substrate at a temperature below 0° C.; Heating step: heating the substrate to above 60° C. so that the byproducts deposited on the substrate are discharged in a gaseous form; The etching step and the heating step are performed alternately.

2. The etching method according to claim 1, characterized in that: The time ratio of the etching step to the heating step is greater than or equal to 1.

3. The etching method according to claim 1, characterized in that: The etching step takes longer than 300 seconds.

4. The etching method according to claim 3, characterized in that: The etching step takes less than 1800 seconds.

5. The etching method according to claim 1, characterized in that: The etching step includes: etching a recessed structure on the substrate, wherein the depth-to-width ratio of the recessed structure is greater than or equal to 40.

6. The etching method according to claim 5, characterized in that: The recessed structure is divided into n sections along the depth direction, and the total time of the etching step of the (k-1)th section recessed structure is less than the total time of the etching step of the kth section recessed structure; wherein n≥2, 2≤k≤n, and n and k are integers.

7. The etching method according to claim 1, characterized in that: The etching step and the heating step are alternately cycled at least 3 times.

8. The etching method according to claim 1, characterized in that: The temperature raising step includes: lifting the substrate so that the substrate is close to the gas shower head at the top of the reaction chamber, and the substrate is heated to above 60°C.

9. The etching method according to claim 1, characterized in that: The temperature raising step includes: providing a heating chamber, transferring the substrate into the heating chamber, and raising the temperature of the substrate to above 60°C.

10. The etching method according to claim 1, characterized in that: The temperature raising step includes: reducing the pressure of the heat-conducting gas on the back side of the substrate to raise the temperature of the substrate to above 60°C.

11. The etching method according to claim 1, characterized in that: In the etching step, the etching gas introduced into the reaction chamber includes: C x F y , C x H y F z One or more of , where x is greater than or equal to 1, y is greater than or equal to 1, z is greater than or equal to 1, and x, y, and z are all positive numbers.

12. The etching method according to claim 11, characterized in that: The etching gas further comprises: a halogen-containing gas, wherein the halogen-containing gas comprises one or more of HBr, HI, Br2 or I2.

13. The etching method according to claim 1, characterized in that: The by-product is composed of any one or more elements of Si, O, I, Br or F.

14. A plasma etching device, characterized in that: include: Reaction chamber; A pedestal is provided in the reaction chamber, the substrate is placed on the pedestal, and a cooling device is provided in the pedestal for cooling the substrate so that the etching step is performed below 0° C.; and A heating device is used to heat the substrate to above 60°C.

15. The plasma etching device according to claim 14, characterized in that: The temperature raising device comprises a gas shower head, which is located in the reaction chamber and arranged opposite to the base. The base is provided with a lifting pin for lifting the substrate so that the substrate is away from the base and close to the gas shower head, and the substrate is heated to above 60°C.

16. The plasma etching device according to claim 14, characterized in that: The temperature increasing device comprises a heating chamber, and the substrate is transferred from the reaction chamber to the heating chamber to increase the temperature of the substrate to above 60°C.

17. The plasma etching device according to claim 14, characterized in that: The cooling device comprises a cooling pipe arranged in the base, a refrigerant flows in the cooling pipe, and the bottom surface of the substrate contacts the refrigerant, so that the etching step is performed below 0°C.

18. The plasma etching device according to claim 17, characterized in that: The temperature of the refrigerant is not higher than -60°C.

19. The plasma etching device according to claim 14, characterized in that: A gas transmission channel is provided in the base, and the gas transmission channel is used to transmit heat-conducting gas to the gap between the substrate and the base.

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