Cleaning method of reaction chamber used in semiconductor or display process

Abstract

The present invention relates to a cleaning method of a reaction chamber used in a semiconductor or display process, the method comprising a step of cleaning off a residue present in at least a portion of the reaction chamber by using a cleaning gas including FNO gas, wherein the residue includes one or more of a silicon nitride film, a silicon oxide film, and an amorphous carbon film.

Description

Cleaning method for a reaction chamber used in semiconductor or display processes

[0001] The present invention relates to a method for cleaning a reaction chamber, and more specifically, to a method for cleaning a reaction chamber that can effectively and environmentally clean various residues present in a reaction chamber equipped with deposition and etching equipment used in semiconductor and display manufacturing processes.

[0002] Generally, a series of processes such as deposition, etching, polishing, and cleaning are performed to manufacture a semiconductor device on a substrate. These processes are carried out in a deposition apparatus equipped with a chamber (e.g., a CVD apparatus) or an etching apparatus. Among these, the deposition process is a process of applying a predetermined deposition material onto a substrate or a material film on a substrate within the chamber of the deposition apparatus, and the etching process is a process of forming an ultrafine structure of a desired shape by selectively removing a portion of the thin film formed on the substrate by the deposition process, etc.

[0003] Typically, as a result of the deposition process, deposition materials remain and adhere as residues not only to the substrate but also to the inner walls of the reaction chamber, components installed inside the chamber, and piping; similarly, as a result of the etching process, etching byproducts adhere to the inner walls of the chamber. Since these residues can cause impurities to adhere to the substrate during subsequent deposition or etching processes, potentially leading to defects in semiconductor devices, it is necessary to frequently clean processing chambers, such as deposition or etching chambers, to remove process byproducts like silicon oxide (SiOx) and silicon nitride (SiN). Meanwhile, although amorphous carbon layers (ACL, a-carbon) are used as hard masks or protective layers in semiconductor and display manufacturing processes, remnant carbon films can remain inside the chamber and on the wafer surface after the process is completed, posing a problem. Therefore, as described above, there is a need for a method to effectively remove all various deposition residues that may be generated during semiconductor and display manufacturing processes.

[0004] Residue removal methods can be broadly classified into dry cleaning and wet cleaning, and each method is selectively applied depending on the specific process environment and the characteristics of the substance to be removed.

[0005] First, the wet cleaning method uses a liquid chemical solution to dissolve and remove deposition residues, and uses acidic or basic solutions. Representative chemical solutions used include Buffered HF (BHF), SC-1 (NH4OH + H2O₂ + H2O), and SC-2 (HCl + H2O₂ + H2O). Since it is generally used for cleaning the surface of semiconductor wafers, the dry cleaning method is more suitable for removing deposition residues.

[0006] Representative examples of dry cleaning methods include cleaning methods using ultraviolet (UV) light sources and plasma cleaning methods using reactive gases.

[0007] To explain in detail, the cleaning method using an ultraviolet (UV) light source is a photochemical cleaning technique that uses a UV light source to activate ozone (O3) or hydrogen peroxide (H2O2) to remove deposition residues. While this method has the advantage of enabling effective cleaning even at low temperatures, it has the limitation that it is not effective for cleaning various deposition residues.

[0008] Plasma cleaning refers to a method of removing deposition residues by reacting active species generated by ionizing gases such as NF₃, CF₄, and O₂ into a plasma state. For example, in the case of NF₃ plasma, fluorine (F*) radicals are generated, which react with silicon oxide (SiO₂) to volatilize into SiF₄, thereby effectively removing deposition residues. Plasma cleaning has the advantages of providing a uniform cleaning effect inside the chamber and facilitating the removal of reaction byproducts. However, there is a potential problem of shortened equipment lifespan due to the possibility of damage to the inner walls or electrodes of the chamber directly exposed to the plasma.

[0009] To address this, the Remote Plasma Source (RPS) method has been researched and utilized. In the RPS method, plasma is generated outside the chamber rather than inside, and the active species produced are introduced into the chamber to perform cleaning. This method is highly effective in that it maintains the advantages of plasma-based cleaning while minimizing damage to internal chamber components. However, NF₃ gas, commonly used in RPS cleaning methods, is a potent greenhouse gas (GHG) with a global warming potential approximately 17,000 times higher than that of carbon dioxide (CO₂) and an atmospheric lifespan of over 500 years, posing a high potential for impact on climate change.

[0010] Therefore, it is still necessary to develop a method capable of effectively cleaning various deposition residues, including silicon oxide films, silicon nitride films, and amorphous carbon films, by introducing a cleaning gas that is more environmentally friendly than previously known methods.

[0011] The present invention aims to solve the problems of the prior art and provides an optimized cleaning method capable of effectively removing various deposition residues by applying FNO (Nitrosyl Fluoride) gas alone or a mixture of FNO gas and NF3 gas to the RPS method.

[0012] The objectives of the present invention are not limited to those mentioned above, and other objectives and advantages of the present invention not mentioned may be understood from the following description and will be more clearly understood from the experimental examples of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0013] To achieve the above objective, according to one embodiment of the present invention, a method for cleaning a reaction chamber used in a semiconductor or display process may be provided, comprising the step of cleaning a residue present in at least a part of a reaction chamber using FNO gas or a mixture of FNO gas and NF3 gas as a cleaning gas, wherein the residue comprises one or more of a silicon nitride film, a silicon oxide film, and an amorphous carbon film.

[0014] When the above-mentioned mixed gas of FNO and NF3 is used as a cleaning gas, when the total volume of the mixed gas combining the FNO gas and NF3 gas is 100 vol%, the FNO gas may be mixed at 10 vol% or more.

[0015] When the total volume of the mixed gas combining the above FNO gas and NF3 gas is 100 vol%, the FNO gas may be mixed in an amount of 30 to 90 vol%.

[0016] The step of cleaning the residue may be carried out in a temperature range of 15 to 25°C and a pressure range of 3 to 5 Torr.

[0017] The step of cleaning the residue comprises: (S1) a step of supplying a cleaning gas through a Mass Flow Controller (MFC) to a Remote Plasma Source (RPS) device; (S2) a step of dissociating the cleaning gas by plasma in the Remote Plasma Source device to form an active species including one or more of F-radicals and NO-radicals; and (S3) a step of supplying the etching species to a reaction chamber to clean the residue; wherein the cleaning gas may be either FNO gas or a mixture of FNO gas and NF3 gas.

[0018] In the step of cleaning the residue above, a dilution gas including one or more of nitrogen (N2) gas, argon (Ar) gas and helium (He) gas may be further supplied.

[0019] The above dilution gas may be supplied at a ratio of 10 to 100% relative to the flow rate of the above cleaning gas.

[0020] The above reaction chamber may be equipped in deposition equipment and etching equipment used in semiconductor or display manufacturing processes.

[0021] The cleaning method of the reaction chamber of the present invention can effectively remove various deposition residues by using FNO gas, which has a lower GWP (Global Warming Potential) than NF3 gas, alone or by mixing FNO gas and NF3 gas and applying it to the RPS method.

[0022] In addition to the effects described above, the effects of the present invention are described together with the details for implementing the invention below.

[0023] Figure 1 is a graph showing the experimental results of cleaning a silicon oxide film while changing the cleaning condition pressure when using NF3 gas and FNO gas individually in Experimental Example 1.

[0024] Figure 2 is a graph showing the experimental results of cleaning a silicon nitride film while changing the cleaning condition pressure when using NF3 gas and FNO gas individually in Experimental Example 2.

[0025] Figure 3 is a graph showing the experimental results of cleaning an amorphous carbon film while varying the cleaning condition pressure when using NF3 gas and FNO gas individually in Experimental Example 3.

[0026] Figure 4 shows the cleaning test performance derived from Experimental Examples 1 to 3 compared with the case of NF3 gas alone.

[0027] Figure 5 is a graph showing the experimental results of cleaning a silicon oxide film while changing the mixing ratio of FNO gas in Experimental Example 4.

[0028] Figure 6 is a graph showing the experimental results of cleaning a silicon nitride film while changing the mixing ratio of FNO gas in Experimental Example 5.

[0029] Figure 7 is a graph showing the experimental results of cleaning an amorphous carbon film while varying the mixing ratio of FNO gas in Experimental Example 6.

[0030] Figure 8 shows the cleaning test performance derived from Experimental Examples 7 and 8 compared with the case of NF3 gas alone.

[0031] The aforementioned objectives, features, and advantages are described in detail below with reference to this specification, and accordingly, a person skilled in the art to which the present invention pertains will be able to easily implement the technical concept of the present invention.

[0032] In describing this specification, specific descriptions of related prior art are omitted if it is determined that such descriptions would unnecessarily obscure the gist of this specification.

[0033] Where terms such as “comprising,” “having,” “consisting of,” “arranging,” or “having” are used for a component in this specification, other parts may be added unless “only” is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise.

[0034] Unless otherwise specifically limited in this specification, units are interpreted as being based on “weight (wt).”

[0035] In interpreting the components in this specification, they are interpreted to include an error range even if there is no separate explicit description.

[0036]

[0037] The present invention will be described in detail below.

[0038] According to the present invention, a method for cleaning a reaction chamber used in a semiconductor or display process can be provided, comprising the step of cleaning a residue present in at least a part of a reaction chamber using FNO gas or a mixture of FNO gas and NF3 gas as a cleaning gas, wherein the residue comprises one or more of a silicon nitride film, a silicon oxide film, and an amorphous carbon film.

[0039] Thus, the present invention can provide an environmentally friendly cleaning method by using FNO gas instead of NF3 gas, which is a cleaning gas conventionally used to clean deposition residues such as silicon nitride films, silicon oxide films, and amorphous carbon films, or by using a cleaning gas mixed with NF3 gas. In addition, compared to the case where only NF3 gas is used as a cleaning gas, the cleaning effect for all three types of deposition residues can be generally improved, and an efficient cleaning process can be implemented by adjusting the pressure according to the cleaning target.

[0040] When the mixed gas comprising the above FNO gas and NF3 gas is used as a cleaning gas, when the total volume of the mixed gas comprising the FNO gas and NF3 gas is set to 100 vol%, the FNO gas may be mixed at a ratio of 10 vol% or more, preferably at a ratio of 30 to 90 vol%, and more preferably at a ratio of 50 to 70 vol%. As described in detail below based on the experimental examples of the present invention, it was confirmed that using FNO gas alone at room temperature—rather than at the high temperature of approximately 100 to 500°C used in the conventional RPS method—shows a superior cleaning effect on silicon nitride films and amorphous carbon films, excluding silicon oxide films. Therefore, to enhance the cleaning effect on silicon oxide films as well, it is desirable to mix FNO gas at a ratio of 30 vol% or more. In addition, experimental results confirmed that when the residue to be mainly removed is an amorphous carbon film, it is possible to mix FNO gas in the range of 10 to 70 vol%, and a high mixing ratio of FNO gas is desirable to implement an environmentally friendly cleaning method. In this way, the mixing ratio of FNO gas can be appropriately adjusted to be applied to various cleaning processes.

[0041] Meanwhile, even when FNO gas is used alone, it exhibits a superior cleaning effect on silicon nitride films within the pressure and temperature range of the present invention compared to when NF3 gas is used alone. Therefore, when the deposition residue to be mainly removed is a silicon nitride film, there is no specific lower limit for the mixing ratio of FNO gas, and it is possible to include 10 vol% or more, but in order to implement an environmentally friendly cleaning method, it is desirable to have a high mixing ratio of FNO gas.

[0042] In the cleaning method of the reaction chamber of the present invention, the step of cleaning the residue may sequentially include the following (S1) to (S3).

[0043] (S1) A step in which cleaning gas passes through a Mass Flow Controller (MFC) and is supplied to a Remote Plasma Source (RPS) device;

[0044] (S2) A step in which, in the remote plasma source device, a cleaning gas is dissociated by plasma to form an active species comprising one or more of F-radicals and NO-radicals; and

[0045] (S3) A step of supplying the above etching species to a reaction chamber to clean the residue.

[0046] The above MFC is a device for precisely controlling and adjusting the flow rate of gas or liquid, and as a device for supplying NF3 gas and FNO gas at an accurate flow rate, it allows for the injection of gases with a controlled mixing ratio as intended in the present invention. In this way, NF3 gas and FNO gas can each pass through the MFC and be supplied to an RPS device (remote plasma source device) at a controlled mixing ratio and flow rate. It is expected that NF₃ can effectively remove silicon oxide films or silicon nitride films by mainly forming F (fluorine radicals) and N (nitrogen radicals) within the plasma, but experimental results showed that FNO gas actually exhibited a higher cleaning effect on silicon nitride films. Within the plasma, FNO can exhibit a very excellent cleaning effect on silicon nitride films and amorphous carbon films by forming F (fluorine radicals), N (nitrogen radicals), and O (oxygen radicals). Therefore, it was experimentally confirmed that various deposition residues can be effectively removed by supplying the cleaning gas of the present invention to form radicals through RPS.

[0047] The step of washing the residue can be carried out at room temperature, i.e., in a temperature range of 15 to 25 ℃ and a pressure range of 3 to 5 Torr, for example, in a temperature range of 20 to 23 ℃ and a pressure range of 3.5 to 4.5 Torr, for example, in a temperature range of 19 to 21 ℃ and a pressure range of 3.5 to 4 Torr. The above temperature range is preferred from the perspective of increasing process efficiency while appropriately controlling the reaction rate. In addition, if the pressure is below the above pressure range, there may be a problem in that the etch rate decreases due to a decrease in the concentration of active species, and if the pressure exceeds the above pressure, there may be a problem in that the concentration of unreacted material increases due to excessively high pressure, thereby reducing the efficiency of the washing process.

[0048] Generally, temperature conditions for implementing a cleaning method require high temperatures of 100 to 500°C or higher, and pressures of 1 to 500 Torr, but the cleaning method of a reaction chamber according to the present invention has the advantage of being able to exhibit excellent cleaning effects even at room temperature and low pressure. In addition, when using the RPS plasma method, the step of cleaning the residue can be operated under power conditions of 30 kW or less.

[0049] According to one example, in step (S1) above, the cleaning gas can pass through a flow controller independently at a flow rate of 100 sccm or more. The flow rate of the cleaning gas can be controlled according to the size of the reaction chamber to which it is applied, and can also vary depending on the type of process to which the cleaning method is applied. For example, when the cleaning method is applied in a semiconductor process, it can be controlled in the range of, for example, 100 to 4000 sccm, for example, 300 to 3000 sccm, for example, 1000 to 2500 sccm. For example, when the cleaning method is applied in a display process, the cleaning gas can be supplied at a flow rate of 10,000 sccm or more. In the present invention, when FNO gas and NF3 gas are mixed as cleaning gases, the flow rates of the two types of gases can be selected according to the mixed volume ratio of FNO gas and NF3 gas. If the flow rate of the cleaning gas in the cleaning method is too low, sufficient radicals may not be generated, which may reduce the cleaning effect; conversely, if it becomes excessively high, the power of the plasma system (e.g., RPS) may become excessively high, leading to a problem of reduced efficiency.

[0050] According to one example, in the step of cleaning the residue, a diluent gas comprising one or more of nitrogen (N2) gas, argon (Ar) gas, and helium (He) gas may be further supplied. By including the diluent gas in this way, plasma can be efficiently formed within a plasma system (e.g., RPS), and as a result, the active species F originating from the cleaning gas can be efficiently transported into the reaction chamber, thereby making cleaning easier.

[0051] According to one example, the dilution gas may be supplied at a ratio of 10 to 100% relative to the flow rate of the cleaning gas, for example, at a ratio of 15 to 80%, for example, at a ratio of 20 to 50%. Therefore, the flow rate of the dilution gas depends on the flow rate of the cleaning gas, and the presence or absence of dilution gas input and the flow rate may be changed according to process conditions and requirements; however, if the above range is exceeded, there may be problems such as a significantly reduced cleaning effect on residues or difficulty in creating an environment for the plasma system.

[0052] According to one example, the reaction chamber is a reactor used in a semiconductor deposition process, and the residue may be a deposition residue generated in a semiconductor deposition process, and specifically, it may be a reaction chamber equipped in a deposition facility and an etching facility used in a semiconductor or display manufacturing process.

[0053]

[0054] The structure and operation of the present invention will be explained in more detail below through preferred experimental examples. However, these are presented as preferred examples of the present invention and should not be interpreted in any way as limiting the present invention.

[0055]

[0056] <Experimental Method - RPS Cleaning Evaluation Method>

[0057] - Targets for cleaning: SiO2, SiN, α-Carbon thin films

[0058] - 6-inch chamber and Remote Plasma Generator (NPP Vone, max 10kW)

[0059] - MFC Flow Rate Range: NF3 and FNO maximum flow rate 4,000 sccm, Argon maximum flow rate 5,000 sccm, Nitrogen maximum flow rate 3,000 sccm

[0060] - Chuck temperature: 20±1℃

[0061] - Exhaust Gas Analysis: FT-IR (@downstream of process chamber)

[0062] - Method for analyzing cleaning effect: Silicon oxide films and silicon nitride films were analyzed by measuring the etch rate (E / R) using a Spectral Ellipsometer, and amorphous carbon films were analyzed by measuring the etch rate (E / R) using an S-TRC (Wonwoo Systems).

[0063]

[0064] <Experimental Examples 1 to 3>

[0065] Using the equipment described in the above <Experimental Method - RPS Cleaning Evaluation Method>, cleaning of a SiO2 film (Experimental Example 1), cleaning of a SiN film (Experimental Example 2), and cleaning of an amorphous carbon film (Experimental Example 3) were performed using NF3 gas and NFO gas, respectively, while varying the pressure from 3 to 5 Torr under ambient temperature (20±1℃). The results are shown in Figures 1 to 3, respectively, and the gas supply flow rate and cleaning conditions are shown in Table 1 below. In addition, based on the results of Figures 1 to 3, the cleaning performance was compared with the case where only NF3 gas is used as in the prior art and is shown in Figure 4.

[0066] [Table 1]

[0067]

[0068] Referring to FIGS. 1 to 3, it was confirmed that when NF3 gas is used alone, the cleaning effect on SiN and SiO2 tends to increase as the chamber pressure increases. On the other hand, FNO gas had a negligible effect on increasing chamber pressure, which had the advantage of not requiring the formation of high-pressure RPS conditions as in the past. Referring to FIG. 4, the cleaning performance of FNO gas and NF3 gas can be evaluated and compared as shown in Table 2 below.

[0069] [Table 2]

[0070]

[0071] Based on these experimental results, a follow-up experiment was conducted as follows to determine whether a synergistic effect occurs in cleaning performance when a mixture of NF3 gas and FNO gas is applied to RPS cleaning.

[0072]

[0073] <Experimental Examples 4 to 6>

[0074] Cleaning experiment

[0075] Using the equipment described in the above <Experimental Method - RPS Cleaning Evaluation Method>, the total flow rate of NF3 gas and NFO gas was set to 2500 sccm under conditions of room temperature (20±1℃) and a pressure of 3 Torr. Cleaning of SiO2 films (Experimental Example 4), cleaning of SiN films (Experimental Example 5), and cleaning of amorphous carbon films (Experimental Example 6) were performed while varying the mixing ratio of NFO gas to the total sum of NF3 gas and NFO gas from 0 vol% to 100 vol%, and the results are shown in Figures 5 to 7, respectively. The gas supply flow rates and cleaning conditions are shown in Table 3 below. In addition, based on the results of Figures 5 to 7, the cleaning performance was compared with the case where only NF3 gas is used as in the conventional technology and is shown in Figure 8.

[0076] [Table 3]

[0077]

[0078] Referring to Figure 8, for the silicon oxide film, the cleaning rate (cleaning effect) increased as the proportion of NF3 gas in the total flow rate of NF3 gas and NFO gas increased, and when FNO gas was mixed at 30 vol%, it exhibited a cleaning effect nearly 100% of that of using NF3 gas alone. For the silicon nitride film, the best cleaning effect was observed when FNO gas was mixed at 50 vol% compared to using NF3 gas alone (a 277% improvement compared to using NF3 gas alone). Additionally, for the amorphous carbon film, the best cleaning effect was observed when FNO gas was mixed at 40 vol% compared to using NF3 gas alone (a 219% improvement compared to using NF3 gas alone).

[0079] It was confirmed that when NF3 gas and FNO gas are mixed and applied to RPS cleaning in this way, the amount of problematic NF3 gas used is reduced, and a synergistic effect is observed in the cleaning effect, thereby securing high etching performance (etch rate).

[0080]

[0081] Although the present invention has been described in more detail with reference to the experimental examples in this specification, this specification is not necessarily limited to the results of such experimental examples and may be modified in various ways within the scope of the technical concept of this specification. Accordingly, the experimental examples disclosed in this specification are intended to explain, not limit, the technical concept of this specification, and the scope of the technical concept of this specification is not limited by such experimental examples. Therefore, the experimental examples described above should be understood as illustrative in all respects and not restrictive. The scope of protection of this specification shall be interpreted by the claims, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of this specification.

Claims

1. A step of cleaning residues present in at least a part of a reaction chamber using FNO gas or a mixture of FNO gas and NF3 gas as a cleaning gas, and The above residue comprises one or more of a silicon nitride film, a silicon oxide film, and an amorphous carbon film, A cleaning method for a reaction chamber used in semiconductor or display processes.

2. In Paragraph 1, When the above mixture of FNO and NF3 gases is used as a cleaning gas, When the total volume of the mixed gas combining the above FNO gas and NF3 gas is set to 100 vol%, the FNO gas is mixed at 10 vol% or more. A cleaning method for a reaction chamber used in semiconductor or display processes.

3. In Paragraph 2, When the total volume of the mixed gas combining the above FNO gas and NF3 gas is set to 100 vol%, the FNO gas is mixed at 30 to 90 vol%. Cleaning method for reaction chambers.

4. In Paragraph 1, The step of washing the residue is carried out in a temperature range of 15 to 25 ℃ and a pressure range of 3 to 5 Torr, A cleaning method for a reaction chamber used in semiconductor or display processes.

5. In Paragraph 1, The step of cleaning the above residue is, (S1) A step in which cleaning gas passes through a Mass Flow Controller (MFC) and is supplied to a Remote Plasma Source (RPS) device; (S2) A step in which, in the remote plasma source device, a cleaning gas is dissociated by plasma to form an active species comprising one or more of F-radicals and NO-radicals; and (S3) A step of supplying the above etching species to a reaction chamber to clean the residue; and The above cleaning gas uses either FNO gas or a mixture of FNO gas and NF3 gas. A cleaning method for a reaction chamber used in semiconductor or display processes.

6. In Paragraph 1, In the step of cleaning the residue above, a dilution gas comprising one or more of nitrogen (N2) gas, argon (Ar) gas, and helium (He) gas is further supplied. A cleaning method for a reaction chamber used in semiconductor or display processes.

7. In Paragraph 6, The above dilution gas is supplied at a ratio of 10 to 100% relative to the flow rate of the above cleaning gas, A cleaning method for a reaction chamber used in semiconductor or display processes.

8. In Paragraph 1, The above reaction chamber is equipped in deposition and etching equipment used in semiconductor or display manufacturing processes, A cleaning method for a reaction chamber used in semiconductor or display processes.

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