An etching method

Abstract

The application discloses an etching method, which comprises the following steps: introducing hydrogen and halogen gas into a process inner cavity of a semiconductor process equipment, so that the hydrogen and the halogen gas react to generate halogen element radicals; etching a silicon thin film to be etched in the process inner cavity through the halogen element radicals, and generating a target gas to be discharged. The above scheme can solve the problem that the structure of the semiconductor process equipment is relatively complex due to the need of setting related devices of glow discharge in order to realize automatic cleaning of the chamber wall deposited film in the related art.

Description

Technical Field

[0001] This invention relates to the field of semiconductor etching technology, and more particularly to an etching method. Background Technology

[0002] With the continuous development of the integrated circuit industry and the gradual shortage of human resources, automated production has become an inevitable trend in the semiconductor industry. In semiconductor process equipment, during the silicon thin film deposition process, the silicon thin film gradually deposits on the chamber wall of the process cavity. When it reaches a certain thickness, the film deposited on the chamber wall gradually peels off from the chamber wall due to stress, forming particles, which seriously affects the yield of silicon thin film in the process. Therefore, it is necessary to regularly disassemble and clean the film deposited on the chamber wall of the process cavity to ensure that the particle level in the chamber environment is low.

[0003] In related technologies, to achieve automated cleaning of the thin film deposited on the chamber wall, a fluorine-containing gas or a chlorine-containing gas is introduced into the process chamber. A glow discharge then decomposes the fluorine-containing gas into fluorine or chlorine atoms. These fluorine or chlorine atoms react with the thin film on the chamber wall to form gaseous compounds, which are then discharged. However, this process requires the configuration of glow discharge-related devices, such as a high-power radio frequency power supply, radio frequency matching circuit, and radio frequency electrodes, resulting in a relatively complex equipment structure. Summary of the Invention

[0004] The etching method disclosed in this invention solves the problem in related technologies where the structure of semiconductor process equipment is relatively complex due to the need to set up glow discharge devices in order to achieve automatic cleaning of the thin film deposited on the chamber wall.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0006] This application discloses an etching method, including:

[0007] Hydrogen and halogen gas are introduced into the process cavity of a semiconductor process equipment to cause the hydrogen and halogen gas to react and generate halogen free radicals.

[0008] The silicon film to be etched in the process cavity is etched by the halogen free radicals, and the target gas is generated and discharged.

[0009] The technical solution adopted in this invention can achieve the following technical effects:

[0010] The etching method disclosed in this application introduces hydrogen and halogen gases into a process cavity, allowing them to react and generate halogen free radicals. These free radicals, with their strong chemical reactivity, etch the silicon film to be etched. The halogen free radicals react with the silicon film to generate a target gas, which is then discharged from the process cavity. This method can etch the silicon film deposited on the cavity wall or the wafer surface within the process cavity, thus achieving automatic cleaning of the cavity wall or surface etching of the wafer. The strong chemical reactivity of the halogen free radicals increases the etching rate. Since the hydrogen and halogen gases react to generate halogen free radicals within the process cavity, glow discharge devices are unnecessary, thus solving the problem of complex equipment structures required for automatic cleaning of deposited films on the cavity walls in related technologies. Attached Figure Description

[0011] Figure 1 This is a flowchart of the first etching method disclosed in an embodiment of the present invention;

[0012] Figure 2 This is a flowchart of the second etching method disclosed in an embodiment of the present invention;

[0013] Figure 3 This is a schematic diagram of an etching method disclosed in an embodiment of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0015] The technical solutions disclosed in the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0016] Please refer to Figures 1 to 3 This invention discloses an etching method that can be used to etch silicon thin films deposited on the chamber walls of a semiconductor process equipment. Of course, the etching method can also be used to etch silicon thin films forming semiconductor wafers, for example, to etch the surface of a wafer to remove a layer of silicon thin film from the wafer surface.

[0017] The disclosed etching methods include:

[0018] S101: Hydrogen and halogen gases are introduced into the process cavity of the semiconductor process equipment so that the hydrogen and halogen gases react to generate halogen free radicals.

[0019] Specifically, hydrogen and halogen gases can be introduced into the process chamber simultaneously, or hydrogen can be introduced first, followed by halogen gas, or vice versa. Halogen gases can be fluorine (F2), chlorine (Cl2), bromine (Br2), iodine (I2), etc.

[0020] Because hydrogen is a strong reducing agent, halogen gases and hydrogen can spontaneously react under certain conditions to form high-energy halogen elements, such as fluorine radicals (F*). Halogen radicals are free radicals with strong chemical reactivity.

[0021] S102: The silicon film to be etched in the process cavity is etched by halogen free radicals, and the target gas is generated and discharged.

[0022] Because halogen radicals are highly reactive, they can react with the silicon film to be etched, generating a target gas that is then released. This target gas could be silicon fluoride gas, silicon chloride gas, etc. Due to their high energy state, halogen radicals cannot remain stable for long periods, making them highly reactive with the silicon film they collide with during their movement. Because of their high reactivity, the reaction rate with the silicon film is rapid, resulting in a relatively high etching rate.

[0023] The etching method disclosed in this application introduces hydrogen and halogen gases into a process cavity, allowing them to react and generate halogen free radicals. These free radicals, with their strong chemical reactivity, etch the silicon film to be etched. The halogen free radicals react with the silicon film to generate a target gas, which is then discharged from the process cavity. This method can etch the silicon film deposited on the cavity wall or the wafer surface within the process cavity, thus achieving automatic cleaning of the cavity wall or surface etching of the wafer. The strong chemical reactivity of the halogen free radicals increases the etching rate. Since hydrogen and halogen gases react to generate halogen free radicals within the process cavity, glow discharge devices are unnecessary, thus solving the problem of complex equipment structures required for automatic cleaning of deposited films on the cavity walls in related technologies.

[0024] When the pressure inside the process chamber is high, the slow gas diffusion rate and short mean free radical length can lead to uneven etching. To improve the uniformity of etching, the disclosed etching method may optionally include:

[0025] S201, before introducing hydrogen and halogen gases into the process cavity of the semiconductor process equipment, control the pressure in the process cavity to be less than a preset threshold.

[0026] Specifically, the preset threshold can be set according to the actual situation. The preset threshold can be set relatively low, for example, no more than 10 Torr. For example, the preset threshold can be 10 Torr. Of course, the preset threshold can also be 1 Torr or 5 Torr, etc. The method of controlling the pressure inside the process cavity is existing technology and will not be elaborated here.

[0027] This embodiment of the application controls the pressure inside the semiconductor process equipment to be below a preset threshold before introducing hydrogen and halogen gases. This lower pressure results in faster gas diffusion and a longer mean free radical length, leading to a more uniform etching rate. Furthermore, in a low-pressure environment, the reaction between hydrogen and halogen gases effectively generates halogen free radicals, thereby increasing the etching rate.

[0028] Since halogen gases and hydrogen can spontaneously react chemically and release a large amount of heat, in order to ensure the safety and controllability of the reaction process equipment, optionally, in the disclosed etching method, hydrogen and halogen gases are introduced into the process cavity of the semiconductor process equipment, including:

[0029] Step A1: Introduce halogen gas into the process cavity.

[0030] Step A2: After the halogen gas is introduced into the process cavity, hydrogen gas is introduced into the process cavity.

[0031] Since hydrogen is a strong reducing agent, this embodiment of the application first introduces halogen gas into the process cavity, and then introduces hydrogen gas into the process cavity, thereby ensuring the safety and controllability of the reaction process.

[0032] In an optional embodiment, the disclosed etching method further includes:

[0033] Step B1: After the halogen free radicals have finished etching the silicon thin film to be etched, stop introducing hydrogen gas into the process chamber.

[0034] Step B2: After stopping the introduction of hydrogen into the process cavity, stop the introduction of halogen gas into the process cavity.

[0035] In this embodiment, after the halogen free radical etching of the silicon thin film to be etched is completed, the introduction of hydrogen gas into the process cavity is stopped first, and then the introduction of halogen gas into the process cavity is stopped. This avoids excessive hydrogen gas remaining in the process cavity, thereby ensuring safety and controllability after etching is completed.

[0036] To further ensure safety and controllability after etching, in the disclosed etching method, after stopping the introduction of hydrogen into the process cavity, the introduction of halogen gas into the process cavity is also stopped. Specifically, step B2 includes: after stopping the introduction of hydrogen into the process cavity, waiting for a first preset time before stopping the introduction of halogen gas into the process cavity. The first preset time can be a manually preset time.

[0037] In this embodiment, after stopping the introduction of hydrogen into the process cavity, a first preset time is waited. During this first preset time, halogen gas is continued to be introduced into the process cavity, so that the hydrogen remaining in the process cavity reacts with the halogen gas, thereby consuming the hydrogen in the process cavity, thus ensuring safety and controllability after etching is completed.

[0038] To purge residual halogen and target gases from the process chamber after etching of the silicon thin film, the disclosed etching method may optionally include:

[0039] Step C1: After waiting for a first preset time and then stopping the introduction of halogen gas into the process cavity, purge gas is introduced into the process cavity to expel the halogen gas and target gas from the process cavity.

[0040] Specifically, the cleaning gas can be nitrogen or an inert gas, etc.

[0041] In this embodiment, after stopping the introduction of halogen gas into the process cavity, a purging gas is introduced into the process cavity, thereby purging the residual halogen gas and target gas in the process cavity through the purging gas.

[0042] Specifically, to ensure that the halogen gas and hydrogen gas remaining in the process cavity react fully within the process cavity, optionally, in the disclosed etching method, after waiting for a first preset time and then stopping the introduction of halogen gas into the process cavity, a purge gas is introduced into the process cavity to remove the halogen gas and target gas from the process cavity, i.e., step C1 includes:

[0043] After waiting for a first preset time and then stopping the introduction of halogen gas into the process cavity, wait for a second preset time before introducing purge gas into the process cavity to expel the halogen gas and target gas from the process cavity.

[0044] The second preset duration can be a duration preset by the user.

[0045] In this embodiment, after waiting for a first preset time and then stopping the introduction of halogen gas into the process cavity, a second preset time is waited before purge gas is introduced into the process cavity to expel the halogen gas and target gas from the process cavity. This allows the halogen gas and hydrogen remaining in the process cavity to react fully within the process cavity, thereby ensuring safety and controllability after etching is completed.

[0046] Since hydrogen is a strong reducing agent, to ensure the safe and controllable reaction between hydrogen and halogen gases within the process chamber, the following can be selected:

[0047] In the disclosed etching method, hydrogen and halogen gases are introduced into the process cavity of the semiconductor process equipment, including:

[0048] Step D1: Introduce hydrogen gas into the process cavity at a first flow rate.

[0049] Step D2: Halogen gas is introduced into the process cavity at a second flow rate.

[0050] Wherein, the first flow rate is less than or equal to the second flow rate.

[0051] In this embodiment of the application, when hydrogen and halogen gas are introduced into the process cavity of a semiconductor process equipment, hydrogen is introduced into the process cavity at a first flow rate and halogen gas is introduced into the process cavity at a second flow rate, wherein the first flow rate is less than or equal to the second flow rate. This avoids excessive hydrogen from causing uncontrollable reactions, thereby making the reaction of hydrogen and halogen gas in the process cavity safe and controllable.

[0052] In one optional embodiment, when the silicon film to be etched is silicon nitride, the halogen gas can be fluorine gas, and the halogen free radicals are fluorine free radicals. The fluorine free radicals etch the silicon nitride, generating silicon fluoride gas and nitrogen gas which are then discharged outside the process cavity. The target gases include silicon fluoride gas and nitrogen gas.

[0053] Specifically, fluorine radicals, due to their high energy state, cannot exist stably for long periods and readily react with silicon nitride they collide with during their movement. Therefore, they have high reactivity and react with silicon nitride at a faster rate, resulting in a higher etching rate. The reaction formula is as follows:

[0054] F*+Si3N4→SiF4+N2.

[0055] Wherein: F* represents fluorine radicals, Si3N4 represents silicon nitride, SiF4 represents silicon fluoride gas, and N2 represents nitrogen gas.

[0056] Because polycrystalline silicon or monocrystalline silicon reacts relatively faster with chlorine radicals, in some embodiments, when the silicon film to be etched is polycrystalline silicon or monocrystalline silicon, the halogen gas can be chlorine gas, the halogen radicals are chlorine radicals, and fluorine radicals can react with polycrystalline silicon or monocrystalline silicon to generate silicon chloride gas. The target gas may include silicon chloride gas. It should be noted that when halogen radicals etch the silicon film to be etched in the process chamber, the process chamber is at a high temperature, and the reaction of hydrogen and chlorine can directly generate silicon chloride gas, which is then discharged.

[0057] In this embodiment of the application, when the silicon film to be etched is polycrystalline silicon or monocrystalline silicon, chlorine gas is used as the halogen gas, so that chlorine free radicals can react well with polycrystalline silicon or monocrystalline silicon, thereby improving the etching rate of polycrystalline silicon or monocrystalline silicon.

[0058] like Figure 3 This is a schematic diagram of an etching method disclosed in this application, where A represents the introduction of halogen gas into the process cavity at a second flow rate, B represents the introduction of hydrogen gas into the process cavity at a first flow rate, and C represents the introduction of purge gas into the process cavity, and the t-axis represents the time axis. Figure 3 The publicly disclosed etching method is as follows:

[0059] Step E1: Introduce halogen gas into the process cavity for a first duration.

[0060] Step E2: After introducing halogen gas into the process cavity for a first duration, hydrogen gas is introduced into the process cavity for a second duration, and then halogen gas is introduced into the process cavity for another second duration.

[0061] Specifically, such as Figure 3 As shown, B indicates that hydrogen gas is introduced into the process cavity at a first flow rate. Before the hydrogen gas is introduced into the process cavity, halogen gas has been introduced into the process cavity for a first duration.

[0062] Step E3: After introducing hydrogen and halogen gas into the process cavity for a second duration, stop introducing hydrogen into the process cavity and continue introducing halogen gas into the process cavity for a third duration.

[0063] Step E4: After introducing halogen gas into the process cavity for a third duration, stop introducing halogen gas and introduce purge gas into the process cavity for a fourth duration.

[0064] The above embodiments of the present invention focus on describing the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be described in detail here.

[0065] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. An etching method, characterized in that, include: Halogen gas is introduced into the process cavity of semiconductor process equipment; After the halogen gas is introduced into the process cavity, hydrogen gas is introduced into the process cavity. The hydrogen gas and the halogen gas undergo a chemical reaction in the process cavity to generate halogen free radicals; The silicon film to be etched in the process cavity is etched by the halogen free radicals, and the target gas is generated and discharged.

2. The etching method according to claim 1, characterized in that, The method further includes: Before introducing hydrogen and halogen gases into the process cavity of the semiconductor process equipment, the pressure in the process cavity is controlled to be less than a preset threshold.

3. The etching method according to claim 1, characterized in that, The method further includes: After the halogen free radicals have completed etching the silicon thin film to be etched, the introduction of hydrogen gas into the process cavity is stopped. After stopping the flow of hydrogen into the process cavity, stop the flow of halogen gas into the process cavity.

4. The etching method according to claim 3, characterized in that, The step of stopping the flow of halogen gas into the process cavity after stopping the flow of hydrogen gas into the process cavity includes: After stopping the flow of hydrogen into the process cavity, wait for a first preset time before stopping the flow of halogen gas into the process cavity.

5. The etching method according to claim 4, characterized in that, The method further includes: After waiting for a first preset time and then stopping the introduction of the halogen gas into the process cavity, purge gas is introduced into the process cavity to expel the halogen gas and the target gas from the process cavity.

6. The etching method according to claim 5, characterized in that, After waiting for a first preset time and then stopping the introduction of the halogen gas into the process cavity, the step of introducing purge gas into the process cavity to expel the halogen gas and the target gas from the process cavity includes: After waiting for a first preset time and then stopping the introduction of the halogen gas into the process cavity, wait for a second preset time and then introduce the purge gas into the process cavity to expel the halogen gas and the target gas from the process cavity.

7. The etching method according to claim 1, characterized in that, The process of introducing hydrogen and halogen gases into the process cavity of the semiconductor process equipment includes: Hydrogen gas is introduced into the process cavity at a first flow rate; The halogen gas is introduced into the process cavity at a second flow rate. Wherein, the first flow rate is less than or equal to the second flow rate.

8. The etching method according to claim 1, characterized in that, When the silicon film to be etched is silicon nitride, the halogen gas is fluorine gas, the halogen free radical is fluorine free radical, and the target gas includes silicon fluoride gas and nitrogen gas.

9. The etching method according to claim 1, characterized in that, When the silicon film to be etched is polycrystalline silicon or monocrystalline silicon, the halogen gas is chlorine gas, the halogen free radical is chlorine free radical, and the target gas includes silicon chloride gas.

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