Substrate etching method and semiconductor processing device
By setting multiple layers to be etched on the substrate and controlling the etch selection ratio, the problem that the angle between the side wall and the bottom surface of the recessed structure in the prior art cannot reach 90°-100°, and a more vertical recessed structure is achieved, which improves the efficiency of subsequent processing.
Patent Information
- Application Number
- CN202311271245.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-27
- Publication Date
- 2025-03-28
AI Technical Summary
The existing substrate etching method cannot etch the angle formed by the side wall and bottom surface of the recessed structure to 90°-100°, resulting in unfavorable subsequent processing.
By providing the first and second etching layers on the substrate, the first etching step and the second etching step are performed respectively, and the etching selection ratio of the second etching layer and the first etching layer to be controlled to be greater than 0.8 so as to form the angle between the side wall and the bottom surface of the recessed structure is 90°-100°.
The side walls of the recessed structure are more vertical, meeting the requirements of the side wall perpendicularity of the subsequent process and improving the efficiency of subsequent processing.
Smart Images
Figure CN119725073A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductors, and in particular to a substrate etching method and a semiconductor processing device. Background Art
[0002] When making logic or flash memory chips, transistors need to be connected to external circuits through metal pads. In order to form transistors in metal pads, a passivation layer must first be deposited on the metal pad, and a recessed structure with an opening is etched out of the passivation layer, and then the metal pad is subsequently processed. The closer the angle formed by the side wall of the recessed structure and the bottom surface of the recessed structure is to 90°, the more it can meet the requirements of subsequent processes. However, existing substrate etching methods can only etch the angle formed by the side wall and the bottom surface of the recessed structure into an obtuse angle greater than 100°, which is not conducive to subsequent processing. Summary of the invention
[0003] The object of the present invention is to provide a substrate etching method and a semiconductor processing device, so as to make the angle between the side wall and the bottom surface of the recessed structure be 90°-100°.
[0004] In order to achieve the above object, the present invention provides a substrate etching method, comprising:
[0005] Providing a substrate, wherein a first layer to be etched and a second layer to be etched are provided on the surface of the substrate, the first layer to be etched covers the surface of the second layer to be etched, and the first layer to be etched and the second layer to be etched are made of different materials;
[0006] Through a first etching step, etching the first to-be-etched layer;
[0007] Through a second etching step, etching the second layer to be etched, wherein the etching selectivity ratio of the second layer to be etched to the first layer to be etched is greater than 0.8;
[0008] After etching is completed, a concave structure is formed on the surface of the substrate, and the angle between the side wall and the bottom surface of the concave structure is 90°-100°.
[0009] Optionally, through a first etching step, the first layer to be etched is etched to form an initial recessed structure, the bottom surface of the initial recessed structure is the surface of the second layer to be etched, and the angle between the sidewall of the initial recessed structure and the bottom surface is 90°-100°;
[0010] In the second etching step, an etching selectivity ratio of the second layer to be etched and the first layer to be etched is greater than 0.8.
[0011] Optionally, through a first etching step, the first layer to be etched is etched to form an initial recessed structure, the bottom surface of the initial recessed structure is the surface of the second layer to be etched, and the angle between the sidewall of the initial recessed structure and the bottom surface is greater than 100°;
[0012] In the second etching step, an etching selectivity ratio of the second layer to be etched and the first layer to be etched is greater than 1.
[0013] Optionally, an etching selectivity ratio of the second layer to be etched to the first layer to be etched is 1.2:1-1.5:1.
[0014] Optionally, the first layer to be etched is a silicon nitride layer, and the second layer to be etched is an oxide layer. The method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: the second etching gas contains at least one of C4F6 or C4F8.
[0015] Optionally, the second etching gas contains at least CF4 and C4F8, and the flow ratio is CF4:C4F8=2:1-10:1.
[0016] Optionally, the first layer to be etched is an oxide layer, and the second layer to be etched is a silicon nitride layer. The method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: the second etching gas contains at least one of CHF3, CH2F2 or CH3F.
[0017] Optionally, the bias power of the first etching step and the second etching step is 150W-1500W.
[0018] Optionally, a method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: adjusting a source power of the first etching step or the second etching step.
[0019] Optionally, a method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: adjusting a temperature of the first etching step or the second etching step.
[0020] Optionally, the first layers to be etched and the second layers to be etched are alternately stacked.
[0021] Optionally, the material of the first layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride; the material of the second layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride.
[0022] Optionally, the substrate is an aluminum liner.
[0023] Optionally, it also includes a third layer to be etched, the material of the third layer to be etched is different from the material of the second layer to be etched, the second layer to be etched covers the surface of the third layer to be etched, and the third layer to be etched is located on a substrate; through a third etching step, the third layer to be etched is etched, and the etching selectivity ratio of the third layer to be etched and the second layer to be etched is greater than 0.8.
[0024] Optionally, the material of the third layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride.
[0025] The present invention also provides a semiconductor processing device, comprising:
[0026] Plasma etching reaction chamber;
[0027] A base, located in the plasma etching reaction chamber, and used for carrying a substrate;
[0028] A radio frequency source, used to excite the gas in the plasma etching reaction chamber into plasma;
[0029] A controller is configured to execute the above substrate etching method.
[0030] Optionally, the semiconductor processing device is an inductively coupled plasma reaction device or a capacitively coupled plasma reaction device.
[0031] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:
[0032] (1) In theory, the greater the bias power, the higher the verticality of the sidewalls of the recessed structure etched by the etching gas on the substrate. However, in practice, when etching the substrate at a larger bias power, the sidewalls of the recessed structure obtained cannot meet the requirements of the subsequent process for the verticality of the sidewalls. The experimental results of etching the substrate at different bias powers of the present invention show that the greater the bias power, the lower the verticality of the sidewalls. Therefore, the present invention further explores the factors that affect the verticality of the sidewalls of the recessed structure, and finds that the etching selectivity ratio of the etching gas for different material layers is the key to affecting the verticality of the sidewalls of the recessed structure. When the etching gas etches the bottom material more, it is easier to open the lower opening of the recessed structure, and the lateral size tends to be consistent with the upper opening, and finally the angle between the sidewall of the recessed structure and the bottom surface approaches 90°, and the sidewall of the recessed structure becomes more vertical.
[0033] (2) When etching the second layer to be etched, the verticality of the side wall of the first layer to be etched is used as a basis for determining the etching selectivity ratio of the etching gas to the second layer to be etched and the first layer to be etched. When the angle between the side wall of the first layer to be etched and the bottom surface is 90°-100°, that is, the verticality of the side wall of the initial recessed structure is better, it is easier to continue to vertically etch the second layer to be etched along the side wall of the initial recessed structure, and the etching rate of the second layer to be etched can be slightly lower than the side etching rate of the first layer to be etched; when the angle between the side wall of the first layer to be etched and the bottom surface is greater than 100°, the etching rate of the second layer to be etched must be strictly greater than the side etching rate of the first layer to be etched. Those skilled in the art can flexibly select the process conditions for the second layer to be etched according to the verticality of the side wall of the first layer to be etched.
[0034] (3) The present invention further provides a method for controlling the etching selectivity ratio. The etching selectivity ratio can be controlled to be greater than 0.8 by adjusting the etching gas type, etching gas flow rate, source RF power, temperature and other process conditions. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 The electron microscope images of the concave structures obtained by etching the substrate at different bias powers, where: Figure 1 (a) is the concave structure obtained by etching the substrate at a bias power of 500W. Figure 1 (b) is the concave structure obtained by etching the substrate at a bias power of 300W. Figure 1 (c) is a concave structure obtained by etching the substrate when the bias power is 150W.
[0036] Figure 2 The present invention provides a flow chart of a substrate etching method.
[0037] Figure 3 This is an electron microscope image of the concave structure obtained in an embodiment of the present invention. DETAILED DESCRIPTION
[0038] 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.
[0039] 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.
[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0041] When etching a recessed structure with an opening on a substrate, the closer the angle formed by the side wall of the recessed structure and the bottom surface of the recessed structure is to 90°, the more it can meet the requirements of subsequent processes. However, the existing substrate etching method can only etch the angle formed by the side wall and the bottom surface of the recessed structure into an obtuse angle greater than 100°, that is, the closer to the bottom surface of the recessed structure, the smaller the lateral size of the recessed structure opening. This obtuse angle is not conducive to subsequent processing.
[0042] Usually, a plasma RF power source is applied to the upper electrode or the lower electrode for high-frequency discharge, so that the process gas generates plasma, and at the same time, a bias RF power source is applied to the lower electrode to provide a negative bias voltage, so that the positive ions in the plasma are accelerated toward the lower electrode to etch a recessed structure. In theory, the higher the power of the bias RF power source and the greater the bias voltage, the better the directionality of the plasma bombardment, and it is easier to form a recessed structure with vertical side walls (that is, the angle between the side wall of the recessed structure and the bottom surface is close to 90°). However, the inventor discovered during the process adjustment that the relationship between the bias power and the verticality of the recessed structure is contrary to the theory. The relationship between the bias power and the verticality of the recessed structure is verified below by etching the substrate at different bias powers.
[0043] First, a substrate is provided, the surface of which is covered with a silicon oxide layer, and the surface of the silicon oxide layer is covered with a silicon nitride layer. The silicon nitride layer and the silicon oxide layer of the substrate are etched under process conditions of bias powers of 500 W, 300 W, and 150 W, respectively, to form a concave structure, and then the angle between the side wall and the bottom surface of the concave structure is measured. It should be noted that Figure 1 (a) to (c) are SEM images at the same magnification. Figure 1 As shown in (a), when the bias power is 500W, the angle is 102.07°; Figure 1 As shown in (b), when the bias power is 300W, the angle is 99.76°; Figure 1 As shown in (c), when the bias power is 150W, the angle is 98.17°. Therefore, the greater the bias power, the greater the angle, that is, the worse the verticality of the sidewall of the recessed structure. According to the rules of this experiment, a sidewall closer to vertical can be obtained by reducing the bias power.
[0044] After investigation, the inventors found that the key to making the angle between the sidewall and the bottom surface of the recessed structure close to 90° is to control the etching selectivity of the etching gas to the adjacent layer to be etched. When etching the silicon oxide layer at different bias powers, the etching speed and etching selectivity of the etching gas for etching the silicon oxide layer and the silicon nitride layer are shown in Table 1 below.
[0045] Table 1 Etching rate and etching selectivity under different bias powers
[0046]
[0047] It can be seen from the table that the greater the etching selectivity ratio of the silicon oxide layer and the silicon nitride layer, the closer the angle between the sidewall and the bottom surface of the recessed structure is to 90°.
[0048] Based on this, Figure 2 As shown, the present invention provides a substrate etching method, comprising:
[0049] Step S1: providing a substrate, wherein a first layer to be etched and a second layer to be etched are provided on the surface of the substrate, wherein the first layer to be etched covers the surface of the second layer to be etched, and the first layer to be etched and the second layer to be etched are made of different materials.
[0050] The method of the present invention does not specifically limit the materials of the first layer to be etched and the second layer to be etched. As long as the materials of the first layer to be etched and the second layer to be etched are different, so that the etching gas has an etching selectivity ratio for the first layer to be etched and the second layer to be etched, the substrate can be etched using the method provided by the present invention. Optionally, the material of the first layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride; the material of the second layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride. For example, the first layer to be etched is a silicon nitride layer, and the second layer to be etched is a silicon oxide layer; the first layer to be etched is a silicon nitride layer, and the second layer to be etched is a silicon oxynitride layer; the first layer to be etched is a silicon oxide layer, and the second layer to be etched is a silicon oxynitride layer.
[0051] In some embodiments, the first to-be-etched layer and the second to-be-etched layer are alternately stacked.
[0052] In some embodiments, the substrate is an aluminum liner.
[0053] Step S2: etching the first to-be-etched layer through a first etching step.
[0054] After the first etching step is completed, an initial recessed structure is formed on the first layer to be etched. The initial recessed structure has an opening and takes the surface of the second layer to be etched as the bottom surface.
[0055] Step S3: etching the second layer to be etched through a second etching step, wherein an etching selectivity ratio of the second layer to be etched to the first layer to be etched is greater than 0.8.
[0056] The etching selectivity refers to the relative etching rate of one material and another material under the same etching conditions. When the etching gas in the second etching step etches the second layer to be etched, the material of the first layer to be etched and the material of the second layer to be etched are both exposed to the environment with the etching gas. In addition to etching the second layer to be etched downward, the etching gas will also cause side etching to the side wall corresponding to the initial recessed structure (i.e., the material of the first layer to be etched that is exposed to the plasma environment first). When the etching rate of the second layer to be etched is greater than that of the first layer to be etched, the etching gas etches the material of the second layer to be etched more than the side etching of the material of the first layer to be etched, so that the lower opening of the recessed structure becomes larger and tends to be consistent with the upper opening. Therefore, the key to obtaining a recessed structure with vertical side walls is to control the etching selectivity of the second layer to be etched and the first layer to be etched, rather than adjusting the bias voltage to control the directionality of plasma bombardment as is commonly believed. In the present invention, in the second etching step, the etching selectivity ratio of the second layer to be etched and the first layer to be etched is controlled to be greater than 0.8, so that the angle between the side wall and the bottom surface of the recessed structure approaches 90 degrees.
[0057] In some embodiments, when the angle between the sidewall and the bottom surface of the initial recessed structure formed in the first etching step is 90°-100°, in the second etching step, the etching selectivity of the second layer to be etched and the first layer to be etched is limited to be greater than 0.8. Since the initial recessed structure at this time already has a sidewall with good verticality, when etching the second layer to be etched on the basis of the initial recessed structure, it is easier to continue to vertically etch the second layer to be etched along the sidewall of the initial recessed structure, and there is no need to strictly control the etching selectivity of the etching gas in the second etching step to be greater than 1. Even if the etching rate of the etching gas to the second layer to be etched is slightly lower than the etching rate of the first layer to be etched, and the side etching of the first layer to be etched is slightly greater than the etching of the second layer to be etched, the recessed structure formed after the second layer to be etched can still have an angle between the bottom surface and the sidewall of 90°-100°.
[0058] In some embodiments, when the angle between the sidewall and the bottom surface of the initial recessed structure formed in the first etching step is greater than 100°, in the second etching step, the etching selectivity ratio of the second layer to be etched and the first layer to be etched is limited to be greater than 1. Since the verticality of the sidewall of the initial recessed structure does not meet the process requirements at this time, when etching the second layer to be etched, it is necessary to strictly control the etching selectivity ratio of the etching gas in the second etching step to be greater than 1. Optionally, the etching selectivity ratio of the second layer to be etched to the first layer to be etched is 1.2:1-1.5:1.
[0059] The technical concept of the present invention is: by controlling the etching selectivity ratio of the second layer to be etched and the first layer to be etched, a concave structure with a morphology that meets the requirements is obtained. Making the etching selectivity ratio greater than 0.8 is the goal of the substrate etching method provided by the present invention. The present invention does not specifically limit the process conditions for achieving an etching selectivity ratio greater than 0.8. Any process conditions that can achieve this goal after adjustment belong to the protection scope of the present invention.
[0060] In some embodiments, by selecting a suitable type of etching gas, an etching selectivity ratio of the second to-be-etched layer to the first stacked structure is achieved to be greater than 0.8.
[0061] In some embodiments, the first layer to be etched is a silicon nitride layer, and the second layer to be etched is an oxide layer. The proportion of fluorine atoms in C4F6 or C4F8 gas is high, and such gas has a faster etching rate for the oxide layer, so the second etching gas contains at least one of C4F6 or C4F8. When the second etching gas contains both CF4 and C4F8, the ratio of CF4 and C4F8 gas is a key factor in controlling the etching selectivity. The present invention further explores the effect of the ratio of CF4 and C4F8 gas on the etching selectivity: a substrate is provided, the surface of the substrate is covered with a silicon oxide layer, and the surface of the silicon oxide layer is covered with a silicon nitride layer. When etching the silicon oxide layer under different ratios of CF4 and C4F8 gas, the etching speed and etching selectivity of the etching gas for etching the silicon oxide layer and the silicon nitride layer are shown in Table 2 below.
[0062] Table 2 Etching rate and etching selectivity under different bias powers
[0063]
[0064] When the flow ratio of CF4 and C4F8 is smaller, the etching selectivity is higher. In order to make the etching selectivity of the second to-be-etched layer and the first stacked structure greater than 1, according to the flow ratio, CF4:
[0065] C4F8=2:1-10:1.
[0066] In some embodiments, the first layer to be etched is an oxide layer, the second layer to be etched is a silicon nitride layer, CHF3, CH2F2 or CH3F contains hydrogen atoms, and this type of gas has a faster etching rate for the silicon nitride layer, so the second etching gas contains at least one of CHF3, CH2F2 or CH3F.
[0067] Both source power and temperature can affect the etching selectivity. In some embodiments, the method for achieving an etching selectivity of the second layer to be etched to the first stacked structure greater than 0.8 includes adjusting the source power of the first etching step or the second etching step; in other embodiments, the method for achieving an etching selectivity of the second layer to be etched to the first stacked structure greater than 0.8 includes: adjusting the temperature of the first etching step or the second etching step.
[0068] In some embodiments, the bias power of the first etching step and the second etching step is 150W-1500W.
[0069] In some embodiments, the surface of the substrate also includes a third layer to be etched, the material of the third layer to be etched is different from the material of the second layer to be etched, the second layer to be etched covers the surface of the third layer to be etched, and the third layer to be etched is located on the substrate; through the third etching step, the third layer to be etched is etched, and the etching selectivity ratio of the third layer to be etched and the second layer to be etched is greater than 0.8.
[0070] The method of the present invention does not specifically limit the material of the third layer to be etched, but only limits that the materials of the third layer to be etched and the second layer to be etched are different, so that the etching gas has an etching selectivity ratio for the third layer to be etched and the second layer to be etched. In some embodiments, the material of the third layer to be etched is one of silicon nitride, silicon oxide, or silicon oxynitride. For example, the first layer to be etched is silicon nitride, the second layer to be etched is silicon oxide, and the third layer to be etched is silicon oxynitride. The first layer to be etched, the second layer to be etched, and the third layer to be etched are alternately stacked.
[0071] After etching is completed, a concave structure is formed on the surface of the substrate, and the angle between the side wall and the bottom surface of the concave structure is 90°-100°.
[0072] The present invention also provides a semiconductor processing device, characterized in that it comprises: a plasma etching reaction chamber; a base located in the plasma etching reaction chamber and used to carry a substrate; a radio frequency source, used to excite the gas in the plasma etching reaction chamber into plasma; and a controller, which is configured to execute the above-mentioned substrate etching method. Optionally, the semiconductor processing device is an inductively coupled plasma reaction device or a capacitively coupled plasma reaction device.
[0073] Example
[0074] This embodiment provides a substrate etching method, comprising:
[0075] Step S1.1: Provide a substrate, the surface of which is provided with a first layer to be etched and a second layer to be etched, the first layer to be etched covering the surface of the second layer to be etched. The substrate is an aluminum liner, the first layer to be etched is a silicon nitride layer, and the second layer to be etched is a silicon oxide layer.
[0076] Step S1.2: etching the first to-be-etched layer through a first etching step.
[0077] In the first etching step, the source power is 2500 W, the bias power is 1100 W, the etching gases are CHF3 and Ar, the flow rate of CHF3 is 300 sccm, the flow rate of Ar is 400 sccm, the pressure in the reaction chamber is 15 mT, and the temperature is 40°C.
[0078] After the first etching step is completed, an initial recessed structure is formed on the first layer to be etched. The initial recessed structure has an opening and takes the surface of the second layer to be etched as the bottom surface. The angle between the sidewall of the initial recessed structure and the bottom surface is greater than 100°.
[0079] Step S1.2: etching the second layer to be etched by a second etching step, wherein the etching selectivity ratio of the second layer to be etched to the first layer to be etched is 1.3:1.
[0080] In the second etching step, the source power is 2500W, the bias power is 300W, the etching gases are CF4, C4F8 and Ar, the flow rate of CF4 is 200sccm, the flow rate of C4F8 is 40sccm, the flow rate of Ar is 300sccm, the pressure in the reaction chamber is 50mT, and the temperature is 40°C.
[0081] After etching, the substrate surface is formed as follows Figure 3 The recessed structure shown has an angle between the sidewall and the bottom surface of 98.53°.
[0082] In summary, in order to obtain a recessed structure with a more vertical sidewall, the present invention first etches the substrate under different bias powers. The experimental results break the conventional understanding of the relationship between the verticality of the sidewall of the recessed structure and the bias power. The present invention further explores the factors that affect the verticality of the sidewall of the recessed structure, and provides a substrate etching method, wherein the first layer to be etched is etched through a first etching step; the second layer to be etched is etched through a second etching step, and the etching selectivity ratio of the second layer to be etched to the first layer to be etched is controlled to be greater than 0.8, so that the lower opening of the recessed structure is opened and the lateral size is consistent with that of the upper opening, and finally the angle between the sidewall of the recessed structure and the bottom surface is close to 90°, and the sidewall of the recessed structure is more vertical.
[0083] 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. A substrate etching method, characterized in that: include: Providing a substrate, wherein a first layer to be etched and a second layer to be etched are provided on the surface of the substrate, the first layer to be etched covers the surface of the second layer to be etched, and the first layer to be etched and the second layer to be etched are made of different materials; Through a first etching step, etching the first to-be-etched layer; Through a second etching step, etching the second layer to be etched, wherein the etching selectivity ratio of the second layer to be etched to the first layer to be etched is greater than 0.8; After etching is completed, a concave structure is formed on the surface of the substrate, and the angle between the side wall and the bottom surface of the concave structure is 90°-100°.
2. The substrate etching method according to claim 1, characterized in that: Through a first etching step, the first layer to be etched is etched to form an initial recessed structure, the bottom surface of the initial recessed structure is the surface of the second layer to be etched, and the angle between the sidewall of the initial recessed structure and the bottom surface is 90°-100°; In the second etching step, an etching selectivity ratio of the second layer to be etched and the first layer to be etched is greater than 0.
8.
3. The substrate etching method according to claim 1, characterized in that: Through a first etching step, the first layer to be etched is etched to form an initial recessed structure, wherein the bottom surface of the initial recessed structure is the surface of the second layer to be etched, and the angle between the sidewall of the initial recessed structure and the bottom surface is greater than 100°; In the second etching step, an etching selectivity ratio of the second layer to be etched and the first layer to be etched is greater than 1.
4. The substrate etching method according to claim 3, characterized in that: The etching selectivity ratio of the second layer to be etched to the first layer to be etched is 1.2:1-1.5:
1.
5. The substrate etching method according to claim 1, characterized in that: The first layer to be etched is a silicon nitride layer, and the second layer to be etched is an oxide layer. The method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: the second etching gas contains at least one of C4F6 or C4F8.
6. The substrate etching method according to claim 5, characterized in that: The second etching gas contains at least CF4 and C4F8, and the flow ratio is CF4:C4F8=2:1-10:
1.
7. The substrate etching method according to claim 1, characterized in that: The first layer to be etched is an oxide layer, and the second layer to be etched is a silicon nitride layer. The method for achieving an etching selectivity ratio of the second layer to be etched to the first stacked structure greater than 0.8 includes: the second etching gas contains at least one of CHF3, CH2F2 or CH3F.
8. The substrate etching method according to claim 1, characterized in that: The bias power of the first etching step and the second etching step is 150W-1500W.
9. The substrate etching method according to claim 1, characterized in that: The method for achieving an etching selectivity ratio of the second to-be-etched layer to the first stacked structure greater than 0.8 comprises: adjusting the source power of the first etching step or the second etching step.
10. The substrate etching method according to claim 1, characterized in that: The method for achieving an etching selectivity ratio of the second to-be-etched layer to the first stacked structure greater than 0.8 includes: adjusting the temperature of the first etching step or the second etching step.
11. The substrate etching method according to claim 1, characterized in that: The first layers to be etched and the second layers to be etched are alternately stacked.
12. The substrate etching method according to claim 1, characterized in that: The material of the first layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride; the material of the second layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride.
13. The substrate etching method according to claim 1, characterized in that: The substrate is an aluminum liner.
14. The substrate etching method according to claim 1, characterized in that: It also includes a third layer to be etched, the material of the third layer to be etched is different from the material of the second layer to be etched, the second layer to be etched covers the surface of the third layer to be etched, and the third layer to be etched is located on a substrate; through a third etching step, the third layer to be etched is etched, and the etching selectivity ratio of the third layer to be etched and the second layer to be etched is greater than 0.
8.
15. The substrate etching method according to claim 14, characterized in that: The material of the third layer to be etched is one of silicon nitride, silicon oxide or silicon oxynitride.
16. A semiconductor processing device, characterized in that: include: Plasma etching reaction chamber; A base, located in the plasma etching reaction chamber, and used for carrying a substrate; A radio frequency source, used to excite the gas in the plasma etching reaction chamber into plasma; A controller configured to execute the substrate etching method according to any one of claims 1-15.
17. The semiconductor processing apparatus according to claim 16, wherein: The semiconductor processing device is an inductively coupled plasma reaction device or a capacitively coupled plasma reaction device.