TWI860660B - A production method of a silicon carbide compound - Google Patents

Abstract

The present invention provides a production method of a silicon carbide compound with a plasma etching resistance ability comprising steps of using a pair of silicon targets as a source of silicon element and a hydrocarbon gas as a source of carbon element; introducing a sputtering gas through a gap between the pair of the silicon targets to blow out the silicon plasma species; reacting the silicon plasma species with the hydrocarbon gas to form a silicon carbide compound in a form of thin film deposited onto a surface of a substrate. The carbon/silicon ratio of the silicon carbide compound can be any constant with the proper control of the parameters of the production method. Compared to the bare silicon wafer, the silicon wafer coated with the silicon carbide compound of the present invention has a great plasma etching resistance performance in a plasma atmosphere containing fluorine and chlorine. The silicon carbide compound of the present invention can be applied as a surface treatment to various types of plasma etching equipment and components, especially to increase their life cycle and to avoid chamber contamination with improvement of wafer qualities and yields.

Description

A method for preparing carbon silicon compound

A method for preparing a carbon silicon compound, in particular, a method for forming the carbon silicon compound in the form of a thin film on the surface of a substrate.

In the plasma etching process of semiconductor manufacturing, the plasma atmosphere not only etches the silicon wafer to pattern the circuit, but also corrodes the vacuum pipeline, airflow nozzle, vacuum chamber and parts in the machine to generate dust or particles, causing vacuum chamber pollution and reducing the service life of parts. In worse cases, the silicon wafer will be contaminated, thereby affecting the etching efficiency, wafer characteristics and yield.

Plasma etching process mainly uses electromagnetic field to activate reactive gas in low pressure environment. These plasma activated gas ions will then react chemically or physically with the material to selectively remove the material. Dry plasma etching technology has the advantages of anisotropic etching, high selectivity, etching depth resolution up to nanometer level and no chemical solution contamination, and it can match the semiconductor vacuum process, so it has become the mainstream of semiconductor etching technology. When fluorine- or even chlorine-containing gases are introduced into the reaction chamber for plasma etching, the etching rate of the wafer can be controlled by adjusting the plasma conditions (frequency and power), bias voltage, plasma atmosphere, and electrode mechanism during the process. However, during the reaction process, the plasma etching behavior in the chamber is omnipresent. In addition to etching the target silicon wafer, the vacuum pipeline, gas flow nozzle, vacuum chamber, and spare parts in the entire plasma etching machine are also exposed to the plasma etching atmosphere for a long time. Therefore, these components are prone to peeling due to plasma erosion, and the peeled dust or particles will contaminate the vacuum chamber, affecting the service life of the vacuum chamber, equipment, and parts in the chamber. In addition, it will also contaminate the silicon wafer, thereby affecting the etching efficiency, wafer characteristics and yield.

The advancement of plasma etching technology is an important key to the development of reactive semiconductor processes. Therefore, the development of plasma-resistant coatings for use in semiconductor plasma etching equipment is an urgent issue.

In view of the fact that the currently used plasma etching resistant materials still have some shortcomings, the present invention provides a plasma etching resistant carbon silicon compound coating material and its process technology development: using gas flow sputtering technology to develop a high-speed growth of plasma etching resistant carbon silicon compound film, which can be applied to the surface modification of various components inside plasma etching equipment to increase the service life of the components, avoid chamber contamination, and improve wafer characteristics and yield.

A method for preparing a carbon-silicon compound, the steps of which include: Providing a hollow cathode unit, which includes two silicon targets placed in parallel in a mask, and forming a slit between the two silicon targets, including a slit inlet and a slit outlet; Applying a plasma power to the two silicon targets in a reduced pressure environment to excite a hollow cathode discharge silicon plasma; Passing a sputtering gas through the slit inlet to blow the hollow cathode discharge silicon plasma to the slit outlet, and passing a carbon hydride gas through the vicinity of the slit outlet; The reacting hollow cathode discharge silicon plasma and the hydrocarbon gas will react to form a carbon silicon compound film, which is blown onto at least part or all of the surface of a substrate for coating.

The silicon target material includes single crystal silicon, polycrystalline silicon, amorphous silicon or a combination thereof.

The sputtering gas includes an inert gas, such as helium, argon and krypton.

Wherein, the hydrocarbon gas includes methane, ethane, ethylene, propylene or acetylene.

The substrate includes a metal or non-metal substrate, such as ceramic or polymer.

The carbon silicon compound film is a compound generated by the reaction of silicon and carbon, and the molecular formula includes _SixCy , wherein: x and _y are arbitrary constants, and the x/y molar ratio includes an arbitrary constant.

The carbon silicon compound film has a film growth rate of more than 5 μm/h.

From the above description, it can be seen that the present invention has the following beneficial effects and advantages:

1. The present invention utilizes gas flow sputtering technology to develop a carbon silicon compound film that grows at a high speed and has plasma etching resistance. The film can be applied to the surface modification of various components inside plasma etching equipment to increase the service life of the components, avoid chamber contamination, and improve wafer characteristics and yield.

2. The carbon-silicon compound film grown by gas flow sputtering deposition of the present invention has the advantages of controllable silicon/carbon composition, high-speed growth and plasma etching resistance, and can be applied to the surface modification of various components inside plasma etching equipment to increase its service life, avoid chamber contamination, and improve wafer characteristics and yield.

The present invention will be technically illustrated and described in detail with several preferred embodiments below. The attached drawings are merely some exemplary representatives or embodiments of the present invention. For those with ordinary knowledge in the field to which the present invention belongs, the present invention can also be applied to other similar situations based on these drawings without making any progressive efforts.

The "system", "device", "unit" and/or "module" used in the present invention below are a method for distinguishing different components, elements, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions. As shown in the present invention, unless the context clearly indicates an exception, the words "a", "an", "a kind" and/or "the" do not specifically refer to the singular, but may also include the plural. In general, the terms "including" and "comprising" only indicate that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements.

Flowcharts are used in the present invention to illustrate the operations performed by the system according to the embodiments of the present invention. It should be understood that the preceding or succeeding operations are not necessarily performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. At the same time, other operations may be added to these processes, or one or more operations may be removed from these processes.

<Example 1>

Please refer to FIG. 1, which is a schematic diagram of a preferred embodiment of a method for preparing a carbon silicon compound of the present invention, wherein the steps include:

Step S1) providing a hollow cathode unit 10, which comprises two silicon targets 11 placed in parallel in a mask 12, and forming a slit 111 between the two silicon targets 11, including a slit inlet 111A and a slit outlet 111B;

Step S2) applying a plasma power to the two silicon targets 11 in a reduced pressure environment to generate a hollow cathode discharge silicon plasma 13;

Step S3) a sputtering gas 14 is introduced through the slit inlet 111A to blow out the hollow cathode discharge silicon plasma 13, and a carbon hydride gas 15 is introduced from the vicinity of the slit outlet 111B;

In step S4), the hollow cathode discharge silicon plasma 13 reacts with the carbon-hydrogen gas 15 to generate a carbon-silicon compound film 16, which is blown out from the slit outlet 111B to coat at least a portion or all of a surface of a substrate 20.

In the aforementioned step S3, the flow rate of the sputtering gas 14 and/or the hydrocarbon gas 15 can be controlled by a mass flow meter.

The silicon target 11 comprises single crystal silicon, polycrystalline silicon, amorphous silicon or a combination thereof, preferably single crystal silicon. The sputtering gas 14 preferably comprises an inert gas, such as helium, argon and krypton, and the preferred embodiment provided by the present invention is argon; the carbon-hydrogen gas 15 comprises methane, ethane, ethylene, propylene, acetylene and other gases containing carbon and hydrogen. The substrate 20 comprises a metal or non-metal substrate surface, wherein the non-metal comprises ceramic or polymer.

The aforementioned carbon silicon compound film 16 is a compound generated by the reaction of silicon and _carbon , and its molecular formula can be expressed as _SixCy , where x and y are the molar numbers of silicon and carbon, respectively, and can be any number. When the x/y molar ratio is equal to 1, it is a stoichiometric silicon carbide; when the x/y molar ratio is less than 1, it is a non-stoichiometric and carbon-rich carbon silicon compound; when the x/y molar ratio is greater than 1, it is a non-stoichiometric and silicon-rich carbon silicon compound.

＜Validity test＞

Please refer to Figures 2a to 2c. The present invention uses the above-mentioned manufacturing method, with polycrystalline silicon as the silicon target 11, argon as the sputtering gas 14, and acetylene as the hydrocarbon gas 15 as an embodiment, and the cross-sectional microstructure and component distribution diagram of the carbon silicon compound film 16 obtained at different acetylene flow rates of (a) 20 sccm, (b) 30 sccm, and (c) 50 sccm. When the acetylene flow rate increases from 20 sccm to 50 sccm, the silicon/carbon molar ratio of the obtained carbon silicon compound film increases from 60/40, 50/50 to 25/75.

Please refer to FIG3 , the present invention uses the above-mentioned manufacturing method, with single crystal silicon as the silicon target 11, argon as the sputtering gas 14 and acetylene as the hydrocarbon gas 15, and the cross-sectional microstructure and component distribution diagram of the obtained carbon silicon compound film 16 under the process time of 16 hours. After the process time reaches 16 hours, the silicon/carbon molar ratio of the obtained carbon silicon compound film 16 is 50/50, and the film thickness can reach 160 μm.

As shown in Figs. 2a-3, the silicon/carbon molar ratio of the carbon-silicon compound film 16 can be controlled by the flow rate of the carbon-hydrogen gas 15 to control the molar number of silicon, and the molar number of carbon can also be controlled by the flow rate of the carbon-hydrogen gas 15. At the same time, by adjusting the process parameters, the film growth rate of the carbon-silicon compound film 16 produced by the present invention can reach 5 μm/h or more, and more preferably 10 μm/h or more. The thickness of the carbon-silicon compound film 16 can reach 150 μm or more, depending on the reaction time.

Next, please refer to Figures 4a and 4b. Figure 4a is a comparative example of a bare silicon wafer, and Figure 4b is the carbon silicon compound film 16 produced by the present invention using the aforementioned manufacturing method. This test is a cross-sectional microscopic morphology of the comparative example of a bare silicon wafer and the embodiment of the present invention after plasma etching for 200 seconds in a SiF ₆ atmosphere. Figures 4a and 4b show that the etching depth of the bare silicon wafer is 1.15 μm, while the etching depth of the present invention is only 0.37 μm. The present invention has the ability to reduce the plasma etching speed by 3.1 times compared to the bare silicon wafer.

Further, FIG. 5a is a comparative example of a bare silicon wafer, and FIG. 5b is a carbon silicon compound film 16 made by the above-mentioned manufacturing method of the present invention. This test is to perform plasma etching for 200 seconds on the comparative example of a bare silicon wafer and the embodiment of the present invention in an atmosphere of SiF ₆ and Cl ₂ , and then obtain the cross-sectional microscopic morphology. As shown in FIG. 5a and FIG. 5b, the etching depth of the comparative example of the silicon wafer is 11.85 μm, and the etching depth of the embodiment of the present invention is only 0.61 μm. The present invention has the ability to reduce the plasma etching speed by 19.4 times compared to the bare silicon wafer.

As shown in Figures 4a to 5b, the carbon silicon compound film 16 produced by the present invention has a plasma etching rate 10 times lower than that of a silicon wafer in a plasma etching atmosphere containing fluorine or fluorine and chlorine, and has the ability to resist plasma etching. Therefore, the carbon silicon compound film 16 has the effect of being applied to the surface modification of various components inside plasma etching equipment to increase its service life, avoid chamber contamination, and improve wafer characteristics and yield.

In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "approximately", "approximately" or "substantially" in some examples. Unless otherwise specified, "approximately", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and the claims are approximate values, which may change according to the required features of the individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the general digit retention method. Although the numerical domains and parameters used to confirm the breadth of the scope in some embodiments of the present invention are approximate values, in specific embodiments, the settings of such numerical values are as accurate as possible within the feasible range.

Finally, it should be understood that the embodiments described in the present invention are only intended to illustrate the principles of the embodiments of the present invention. Other variations may also fall within the scope of the present invention. Therefore, as an example and not a limitation, alternative configurations of the embodiments of the present invention may be considered consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly introduced and described herein.

10 Hollow cathode unit 11 Silicon target 111 Slit 111A Slit inlet 111B Slit outlet 12 Mask 13 Hollow cathode discharge silicon plasma 14 Sputtering gas 15 Carbon hydrogen gas 16 Carbon silicon compound film 20 Substrate

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some examples or embodiments of the present invention, and are not absolutely used to limit the technical scope of the present invention. Unless it is obvious from the preceding and following texts or otherwise explained, the same reference numerals in the figures represent the same structure or operation. Among them: Figure 1 is a schematic flow chart of a preferred embodiment of a method for preparing a carbon silicon compound of the present invention. Figures 2a~2c are cross-sectional micromorphologies and component distribution diagrams of the carbon silicon compound film obtained in the preferred embodiment of the present invention at different acetylene flow rates of (a) 20 sccm, (b) 30 sccm and (c) 50 sccm. FIG3 is a cross-sectional micromorphology and component distribution diagram of the carbon silicon compound film obtained in the preferred embodiment of the present invention with a process time of 16 hours. FIG4a is a cross-sectional micromorphology of a bare silicon wafer comparative example after plasma etching for 200 seconds in SiF ₆ atmosphere. FIG4b is a cross-sectional micromorphology of a preferred embodiment of the present invention after plasma etching for 200 seconds in SiF ₆ atmosphere. FIG5a is a cross-sectional micromorphology of a bare silicon wafer comparative example after plasma etching for 200 seconds in SiF ₆ and Cl ₂ atmosphere. FIG5b is a cross-sectional micromorphology of a preferred embodiment of the present invention after plasma etching for 200 seconds in SiF ₆ and Cl ₂ atmosphere.

10 Hollow cathode unit 11 Silicon target 111 Slit 111A Slit inlet 111B Slit outlet 12 Mask 13 Hollow cathode discharge silicon plasma 14 Sputtering gas 15 Carbon hydrogen gas 16 Carbon silicon compound film 20 Substrate

Claims (9)

A method for preparing a carbon-silicon compound comprises the following steps: providing a hollow cathode unit, which comprises two silicon targets placed in parallel in a mask, and forming a slit between the two silicon targets, comprising a slit inlet and a slit outlet; applying a plasma power to the two silicon targets in a reduced pressure environment to stimulate a hollow cathode discharge silicon plasma; introducing a sputtering gas through the slit inlet to blow out the silicon plasma; The hollow cathode discharge silicon plasma is discharged to the slit outlet, and a carbon hydride gas is introduced near the slit outlet; the hollow cathode discharge silicon plasma and the carbon hydride gas react to form a carbon silicon compound film, which is blown out to cover at least part or all of the surface of a substrate; and the silicon/carbon molar ratio of the carbon silicon compound film is controlled by changing the flow rate of the sputtering gas and/or the carbon hydride gas. The method for preparing a carbon silicon compound as described in claim 1, wherein: the flow rate of the sputtering gas and/or the hydrocarbon gas is controlled by a mass flow meter. The method for preparing a carbon-silicon compound as described in claim 1 or 2, wherein: the silicon target material comprises single crystal silicon, polycrystalline silicon, amorphous silicon or a combination thereof. A method for preparing a carbon silicon compound as described in claim 1 or 2, wherein: the sputtering gas contains an inert gas. The method for preparing a carbon silicon compound as described in claim 4, wherein: the inert gas includes helium, argon and krypton. The method for preparing a carbon silicon compound as described in claim 1 or 2, wherein: the hydrocarbon gas contains methane, ethane, ethylene, propylene or acetylene. The method for preparing a carbon silicon compound as described in claim 1 or 2, wherein: the substrate comprises a metal or non-metal substrate. The method for preparing a carbon silicon compound as described in claim 7, wherein: the non-metallic substrate comprises ceramics or polymers. The method for preparing a carbon silicon compound as claimed in claim 1 or 2, wherein: the carbon silicon compound film is a compound generated by the reaction of silicon and _carbon , and the molecular formula includes _SixCy , wherein: x and y are arbitrary constants, and the x/y molar ratio includes an arbitrary constant.