SEMICONDUCTOR PROCESSING EQUIPMENT PART AND METHOD FOR MAKING THE SAME

A part is adapted to be used in a semiconductor processing equipment. The part includes a substrate and a protective coating. The protective coating covers at least a part of the substrate, is made of silicon carbide, and has an atomic ratio of carbon in the protective coating increases in a direction away from the substrate while an atomic ratio of silicon in the protective coating decreases in the direction. The atomic ratio of silicon in the protective coating is larger than that of the carbon near the substrate, and the atomic ratio of silicon in the protective coating is smaller than that of carbon near the outer surface of the protective coating. A method for making the part is also provided.

FIELD OF INVENTION

The disclosure relates to an equipment part, more particularly to a part of a semiconductor processing equipment and a method for making the part.

BACKGROUND OF THE INVENTION

In the field of semiconductor technology, various pieces of semiconductor processing equipment are required for making semiconductor chips. Those pieces of equipment may include, but not limited to, thin film deposition equipment, etching equipment, photolithography equipment, etc. Such equipment include various parts or components, e.g., focus rings, edge rings, chamber walls, etc. that requires protection in order to withstand long-term use of the processing equipment. Protective layers are often formed on substrates of the parts to provide protection to the parts. For example, new protecting layers may be formed on the substrates of the parts once the old protective layers are damaged during semiconductor manufacturing processes, allowing the parts to be reused. However, the protecting layers might be easily peeled off from the parts due to various factors, such as interlayer stress, lattice mismatch, etc. Therefore, it is desirable in the art to provide a part with a protecting layer that has superior adhesion to the substrate and that is durable enough to withstand regular use.

Furthermore, in a plasma etching process of semiconductor manufacturing, the plasma atmosphere not only etches a silicon wafer in a designed pattern but also erodes vacuum pipelines, gas nozzles, vacuum chambers, and components inside equipment, producing dust or particles. This contamination can reduce a lifespan of components and, more seriously, contaminate the silicon wafer, thereby affecting etching efficiency, wafer characteristics, and yield.

Plasma etching processes, like dry plasma etching conventionally operate in low-pressure environments, where an electromagnetic field activates reaction gases into a plasma state as gas ions. These plasma-activated gas ions then chemically react with or physically bombard target material and selectively remove it.

Dry plasma etching technology offers advantages such as anisotropic etching, high selectivity, nano-scale etching depth resolution, and absence of chemical solution contamination. These benefits make it a mainstream technology in semiconductor etching processes, compatible with conventional semiconductor vacuum processes. When fluorine-containing or chlorine-containing gases are introduced into the reaction chamber for plasma etching, an etching rate of the wafer can be controlled by adjusting plasma conditions (frequency or power), bias, plasma atmosphere, and electrode configuration. However, during the reaction process, plasma etching behaviors occur ubiquitously within the chamber. In addition to etching the target silicon wafer, the vacuum pipelines, gas nozzles, vacuum chambers, and components inside the entire plasma etching equipment are also exposed to the plasma atmosphere in prolonged periods. As a result, these components will be eroded by the plasma, leading to peeling or damaging. These dust or particles will contaminate the vacuum chamber, affecting the lifespan of the chamber, machinery, and internal components. Furthermore, this contamination can affect the processing of silicon wafer, subsequently impacting etching efficiency, wafer characteristics, and yield.

Developments of the plasma etching technology are crucial for the semiconductor processes. Therefore, developing plasma-resistant coatings for semiconductor plasma etching equipment is an urgent issue now.

SUMMARY OF THE INVENTION

According to one aspect of the disclosure, a production method of silicon carbide compounds comprising steps of: providing a hollow cathode unit; wherein the hollow cathode unit comprises two silicon targets placed parallel to each other within a case forming a slit therebetween defining a slit inlet and a slit outlet; applying a plasma power to the two silicon targets to ignite a hollow cathode discharge silicon plasma in a reduced-pressure environment; introducing a sputtering gas through the slit inlet to blow out the ho

According to one aspect of the disclosure, a part is adapted to be used in a semiconductor processing equipment. The part includes a substrate made of silicon, and a protective coating that covers at least a part of the substrate. An atomic ratio of carbon in the protective coating increases in a direction away from the substrate, and an atomic ratio of silicon in the protective coating decreases in the direction. The atomic ratio of silicon in the protective coating is larger than that of carbon near the substrate and the atomic ratio of silicon in the protective coating is smaller than that of carbon near the outer surface of the protective coating.

In accordance to above description, the present invention has the following beneficial effects and advantages:

1. The present invention utilizes a new sputtering technology to develop a high-speed growth process for silicon carbide compound films with excellent plasma-resistant properties. These films can be applied to the surface of various components of the internal surface of plasma etching equipment, thereby increasing the lifetime of these components, preventing chamber contamination, and improving wafer characteristics and yield.

2. The silicon carbide compound films produced by the present invention have controllable silicon/carbon composition, high growth rate, and plasma-resistant properties. This enables their application in the surface of various components of the internal surface of plasma etching equipment, thus increasing their lifetime, preventing chamber contamination, and improving wafer characteristics and yield.

THE PREFERRED EMBODIMENTS

With reference toFIG.1, a flowchart illustrates a preferred embodiment of a production method of silicon carbide compounds according to the present invention comprising steps of:

Step S1) Providing a hollow cathode unit10. The hollow cathode unit10comprises two silicon targets11placed parallel to each other within a mask12, forming a slit111between the two silicon targets11, defining a slit inlet111A and a slit outlet111B.

Step S2) Applying a plasma power to the two silicon targets11to excite a hollow cathode discharge silicon plasma13in a reduced-pressure environment and preferred in a chamber (now shown in the figure);

Step S3) Introducing a sputtering gas14through the slit inlet111A to blow out the hollow cathode discharge silicon plasma13, and introducing a hydro-carbon gas15near the slit outlet111B. The hydro-carbon gas15of the present invention is preferred to be non-ionized gas.

Step S4) Reacting the hollow cathode discharge silicon plasma13with the hydro-carbon gas15to form a silicon carbide compound film16to coat at least a part or an entire surface of a substrate20.

In the aforementioned Step S3, a flow rate of the sputtering gas14and/or the hydro-carbon gas15are preferred to be controlled by a mass flow controller.

The silicon target11comprises monocrystalline silicon, polycrystalline silicon, amorphous silicon, or a combination thereof. Monocrystalline silicon is used for this preferred embodiment. The sputtering gas14preferably comprises an sputtering gas, such as helium, argon, or krypton. Argon is used for this preferred embodiment. The hydro-carbon gas15is a gas containing carbon and hydrogen such as methane, ethane, ethylene, propylene, acetylene, or combination thereof. The substrate20could be any substrate includes metallic or non-metallic surfaces. The non-metallic surfaces include ceramics or polymers.

The silicon carbide compound film16is a compound formed by the reaction of the hollow cathode discharge silicon plasma13(silicon source) and the hydro-carbon gas15(carbon source), which can be represented by the molecular formula SixCy, where x and y represent mole numbers of silicon and carbon, respectively, and can be any number, preferably positive number, more preferably positive integer. When the x/y mole ratio is 1, it is stoichiometric silicon carbide; when the x/y mole ratio is less than 1, it is non-stoichiometric and carbon-rich silicon carbide compound; when the x/y mole ratio is greater than 1, it is non-stoichiometric and silicon-rich silicon carbide compound.

Referring toFIG.2, in some embodiments, the aforementioned substrate20(hereinafter in theFIG.2as402) is a closed-loop object, and is exemplified to be ring-shaped, but other suitable shapes are also possible, according to practical requirements. A cross-section of the substrate402along line IV-IV ofFIG.2is shown inFIG.3. In some embodiments as shown inFIG.2andFIG.3, the substrate402has a main body404that has opposite inner and outer surfaces410,412, opposite upper and lower surfaces406,408, and a horizontal surface414and vertical surface416that cooperates with the horizontal surface414to define a step. In some embodiments, the horizontal surface414may be substantially perpendicular to the inner surface410; but in other embodiments, the horizontal surface414may be inclined relative to the inner surface410. In some embodiments, the vertical surface416may be substantially perpendicular to the upper surface406; but in other embodiments, the vertical surface416may be inclined relative to the upper surface406.

Referring toFIG.1, in step S3, an sputtering gas is introduced into the chamber through a gas inlet (not shown) of the chamber. In some embodiments, the sputtering gas may be Ar, He, Ne, Kr, or any combination thereof. In some embodiments, the flow rate of the sputtering gas may range from 0.1 slm to 100 slm, but other ranges are also possible based on practical requirements.

The hydro-carbon gas is preferrably introduced into the chamber through another gas inlet (not shown) of the chamber. In some embodiments, the hydro-carbon gas includes an element of carbon (e.g., C2H2, CH4, etc.). In some embodiments, the hydro-carbon gas may be a hydrocarbon gas having a formula of CnH(2n−2), CnHn, CnH(2rn+2), or other suitable formulas, where n is a positive integer. In some embodiments, the flow rate of the hydro-carbon gas may range from 0.1 sccm to 1000 sccm, but other ranges are also possible based on practical requirements.

Referring toFIG.1, the sputtering gas is ionized into plasma including ions that bombard the silicon targets11, causing silicon atoms and/or silicon ions to sputter out from the silicon targets11and to react with the hydro-carbon gas so as to form the silicon carbide compound film16or a protective coating418as shown inFIG.4and onward made of silicon carbide that covers at least a part of the substrate402, thereby obtaining the part400which includes the substrate402and the protective coating418covering at least a part of the substrate402. The protective coating418, for example, can protect the substrate402of the part400from being damaged by dry etch gas (e.g., Cl2, F2, O2, CF4, C3F8, CHF3, XeF2, SF6, HBr, chloride gases, etc.) when the part400is used in an etching equipment. In some embodiments, a plasma power for ionizing the sputtering gas ranges from 0.1 kW to 100 kW, but other ranges are also possible based on practical requirements. In some embodiments, the protective coating418is formed at a rate of not less than 5 μm/h, and preferably over 10 μm/h. In some embodiments, the protective coating418may have a minimum thickness not less than 150 μm. Referring further toFIG.4, in some embodiments, a plurality of covering units500may be attached to the substrate402during the formation of the protective coating418, such that only a desired part of the substrate402is exposed and formed with the protective coating418. For example, as shown inFIGS.3and4, the lower surface408, the inner surface410and the outer surface412of the main body404of the substrate402may be covered by the covering units500such that only the upper surface406, the horizontal surface414and the vertical surface416of the substrate402are covered with the protective coating418. After forming the protective coating418, the covering units500are removed from the substrate402. In some embodiments, the covering units500may be jigs, masks, tapes, any combination thereof, or other suitable materials.

FIGS.5to10schematically show different variations of the silicon carbide compound film16or the protective coating418. Referring toFIGS.3and5, the protective coating418may cover the upper surface406, the vertical surface416and a part of the horizontal surface414of the substrate402. Referring toFIGS.3and6, the protective coating418may cover the upper surface406, the vertical surface416, the horizontal surface414and a part of the outer surface412of the substrate402. Referring toFIGS.3and7, the protective coating418may cover the upper surface406, the vertical surface416, the horizontal surface414, and a part of the inner surface410of the substrate402. Referring toFIGS.3and8, the protective coating418may cover the upper surface406, the vertical surface416, the horizontal surface414, a part of the inner surface410and a part of the outer surface412of the substrate402. Referring toFIGS.3and9, the protective coating418may cover the upper surface406, the vertical surface416, the horizontal surface414, the inner surface410and the outer surface412of the substrate402. Referring toFIGS.3and10, the protective coating418may entirely cover the main body404of the substrate402, including the upper surface406, the lower surface408, the inner surface410, the outer surface412, the horizontal surface414, and the vertical surface416. In addition, each of the examples shown inFIGS.3to9may be selectively added with an anti-warpage layer (not shown) on the lower surface408in case the stress of the protective coating418causes the substrate402to bend. The material of the anti-warpage layer may also be selected as silicon carbide but is not limited to silicon carbide as long as it can compensate the warpage of the substrate402.

Referring toFIGS.1, in some embodiments, an even number of the silicon targets11are placed in the chamber. In some embodiments, the silicon targets308as shown inFIG.11are arranged in at least one pair with the silicon targets308facing each other. Specifically, if the number of the silicon targets308is two, the silicon targets308may be mounted to the chamber to be located opposite to each other, or may be placed closer to each other (seeFIG.11) with a short distance such as several millimeters to hundreds of millimeters. With the number of the silicon targets11or308being even, the plasma and/or the gas atoms/ions would be more likely to bombarde the silicon targets308, which may result in formation of a denser silicon carbide protective coating418. If the number of the silicon targets308is greater than two, such as four, six, eight, etc., the silicon targets308may be arranged as multiple pairs. For example, as shown inFIG.12, there are three pairs of silicon targets308disposed above the substrate402by equiangular arrangement. In some embodiments, the substrate402such as a closed-loop object or ring rotates about a virtual center axis (L) during formation of the protective coating418in order to adjust or improve the uniformity of the protective coating418. In some embodiments, two sides of each pair of the silicon targets308are provided with magnets501to produce magnetic field to control the plasma located within the magnetic field in order to improve efficiency of forming the silicon atoms/ions or adjust plasma erosion uniformity of the pair of the silicon targets308.

Referring toFIGS.3to10, in some embodiments, the substrate402may be biased to have a lower voltage relative to the plasma. For example, when the plasma is positively charged (e.g., plasma containing Ar+), the substrate402is negatively changed, thereby attracting some ions of the plasma to bombard the substrate402. The attracted ions of plasma may clean the surfaces of the substrate402by removing native oxidized layers formed thereon when the substrate402is exposed to air, moisture or other substances. Furthermore, the plasma having gas ions such as Ar+may create dangling bonds on the surfaces of the substrate402which may be reactive to the silicon atoms, silicon ions, carbons, and/or silicon carbide. Therefore, the protective coating418may be physically and/or chemically connected to the substrate402(e.g., the protective coating418is connected to the substrate402through chemical bonding with the dangling bonds), so that the protective coating418may be more firmly adhered to the substrate402.

Referring toFIGS.3-10, in some embodiments, the substrate402may be heated by the heater306, such that the protective coating418may be more firmly adhered to the substrate402and/or the crystallinity of the protective coating418may be increased (i.e., the protective coating418being made denser). The heating temperature may be any temperature ranging from room temperature to a temperature lower than the melting points of the substrate402and the protective coating418(i.e., silicon carbide).

In some embodiments, during the formation or deposition of the protective coating418, a holder (not shown in Figures) that is disposed in the chamber, and a plurality of silicon targets308that are placed in the chamber. In some embodiments, the silicon targets308, in even numbers, may be disposed parallel to each other above and perpendicular to the holder. In some embodiments, the present invention further includes a heater that is used for heating the holder. The heater may be a graphite heater, an IR laser heater or other suitable heating devices. The heater may be disposed in the chamber or outside of the chamber, as long as the holder can be effectively heated.

In some preferred embodiments, the holder may be rotated, horizontally moved, and/or vertically moved to rotate or move the substrate402for various purposes, e.g., adjusting the uniformity of the protective coating418, etc.

Validation Tests for Embodiment 1

FIG.13is a schematic sectional view taken from circle (A) shown inFIG.4. In some embodiments as shown inFIG.3, the main body404of the substrate402may be formed with a plurality of microstructures420such as protrusions before the formation of the protective coating418, such that, after the protective coating418is formed on the main body404of the substrate402, the stress between the substrate402and the protective coating418can be reduced and the protective coating418can be more firmly attached to the substrate402. In some embodiments, each of the microstructures420may have a height (H) in a range from 300 nm to 1.5 μm and the protective coating418thereon has a minimum thickness (T) of not less than 10 μm. Referring toFIG.14, in some embodiments, each of the microstructures420is pyramid-shaped and has a triangular cross-section. The microstructures420may be formed by etching the substrate402with a suitable etchant, may be formed by deposition techniques, or formed using other suitable techniques. In some embodiments, the substrate402made of silicon may be etched by potassium hydroxide (KOH), tetramethyl ammonium hydroxide (TMAH), ethylenediamine pyrocatechol (EDP), etc.

FIG.15is a scanning electron microscope (SEM) image of an example of the part400. In the process for making this example, the sputtering gas is Ar with a flow rate ranging from 0.1 slm to 100 slm, but other ranges are also possible based on practical requirements. The hydro-carbon gas is C2H2with a flow rate ranging from 0.1 sccm to 1000 sccm, but other ranges are also possible based on practical requirements. The pressure within the chamber302ranges from 10−1torr to 10−2torr, but other ranges are also possible based on practical requirements. The plasma power for ionizing the sputtering gas initially ranges from 0.1 kW to 1 kW, but other ranges are also possible based on practical requirements. Then, the plasma power is increased to a range of 1 kW to 100 kW, but other ranges are also possible based on practical requirements. The temperature of the deposition process may be below 250° C., but other ranges are also possible based on practical requirements. For example, a deposition temperature of 700° C. can increase the ratio of crystalline silicon carbide which enhances the etch resistance capability of the protective coating418. In other words, in some embodiments of the method for making the part400, at least one of the flow rate of the sputtering gas, the flow rate of the hydro-carbon gas, and the plasma power for ionizing the sputtering gas dynamically changes and ends up with a larger numerical value compared to an initial numerical value (i.e., the abovementioned values may be dynamically increased) during the process of formation of the protective coating418.

With reference toFIGS.15to18, the present application uses the aforementioned production method, with monocrystalline silicon as the silicon target11, argon as the sputtering gas14, and acetylene as the hydro-carbon gas15, the cross-sectional microstructure and composition distribution of the silicon carbide compound film16obtained under different acetylene flow rates: (a) 20 sccm, (b) 30 sccm, and (c) 50 sccm are shown. As the acetylene flow rate increases from 20 sccm to 50 sccm, the silicon/carbon mole ratio of the silicon carbide compound film increases from 60/40, 50/50 to 25/75.

With reference toFIG.18, the present application uses the aforementioned production method, with monocrystalline silicon as the silicon target11, argon as the sputtering gas14, and acetylene as the hydro-carbon gas15, the cross-sectional microstructure and composition distribution of the silicon carbide compound film16obtained after 16 hours of processing time are shown. In this preferred embodiment, after 16 hours of processing time, the silicon/carbon mole ratio of the silicon carbide compound film16is 50/50, and the film thickness can reach 160 μm.

From the results ofFIGS.15to18, the silicon/carbon mole ratio of the silicon carbide compound film16can be controlled by the flow rate of the hydro-carbon gas15. Additionally, by adjusting the process parameters, the growth rate/yield of the silicon carbide compound film16produced by the present invention can reach over 5 μm/h in thickness, and preferably over 10 μm/h. The thickness of the silicon carbide compound film16can reach over 150 μm, depending on the reaction time.

As shown inFIGS.15and16, the silicon carbide compound film16or the protective coating418of the part400was formed to have a first portion422and a second portion424. The first portion422is connected to the substrate402and the second portion424, and has a larger atomic ratio of silicon near the substrate402than that of the second portion424.

As shown inFIG.15, the carbon content (i.e., the atomic ratio of carbon) in the protective coating418increases along the line (L1) (e.g., increases in a direction away from the substrate402), and the silicon content (i.e., the atomic ratio of silicon) in the protective coating418decreases in the direction away from the substrate402. In other words, an atomic ratio of silicon is larger than the atomic ratio of carbon near the substrate402. On the contrary, the atomic ratio of silicon is smaller than the atomic ratio of carbon near the outer surface of the protective coating418away from the substrate402. More specifically, the atomic ratio of silicon is larger than 75% while that of carbon is smaller than 25% near the substrate402and the atomic ratio of carbon is about 70% while that of silicon is about 30% near the outer surface of the protective coating418. The average relative content of silicon to carbon in the protective coating418is near 3/2 (i.e., Si:C=60:40). The curve of silicon element and the curve of carbon intersect at a point larger than one half of the distance from the substrate402. As a result, the silicon content as a whole would be larger than the carbon content as a whole in the protective coating418. When the substrate402is made of silicon, and by having the protective coating418with a high silicon content close to the substrate402, the protective coating418may be more firmly adhered to the substrate402. As shown inFIG.16, the carbon content (i.e., atomic ratio of carbon) in the protective coating418increases along the line (L2) (e.g., increases in a direction away from the substrate402), and the silicon content (i.e., atomic ratio of silicon) in the protective coating418decreases in the direction away from the substrate402. In other words, an atomic ratio of silicon is larger than that of carbon near the substrate402. On the contrary, the atomic ratio of silicon is smaller than that of carbon near the outer surface of the protective coating418away from the substrate402. More specifically, the atomic ratio of silicon is larger than 70, while that of carbon is smaller than 30% near the substrate402and the atomic ratio of carbon is larger than 70% while that of silicon is smaller than 30% near the outer surface of the protective coating418. The average relative content of silicon to carbon in the protective coating418is near 1 (i.e., Si:C=50:50). The curve of silicon element and the curve of carbon intersect at a point around one half of the distance from the substrate402. As a result, the carbon content as a whole would be nearly equal to the silicon content as a whole in the protective coating418.

FIG.19is an SEM image of yet another example of the part400. In the process for making this example, the sputtering gas is Ar with a flow rate ranging from 0.1 slm to 100 slm, but other ranges are also possible based on practical requirements. The hydro-carbon gas is C2H2with a flow rate ranging from 0.1 sccm to sccm, but other ranges are also possible based on practical requirements. The pressure within the chamber ranges from 10−1torr to 10−2torr, but other ranges are also possible based on practical requirements. The plasma power for ionizing the sputtering gas initially ranges from 0.1 kW to 100 kW, but other ranges are also possible based on practical requirements. Then, the plasma power is increased to a range of 0.1 kW to 1 kW, but other ranges are also possible based on practical requirements. Afterwards, the plasma power is further increased to a range of 1 kW to 100 kW, but other ranges are also possible based on practical requirements. The temperature of the deposition process may be below 250° C., but other ranges are also possible based on practical requirements. For example, a deposition temperature of 700° C. can increase the ratio of crystalline silicon carbide which enhances the etch resistance capability. In other words, in some embodiments of the method for making the part400, at least one of the flow rate of the sputtering gas, the flow rate of the hydro-carbon gas, and the plasma power for ionizing the sputtering gas dynamically changes and ends up with a larger numerical value compared to an initial numerical value (i.e., the abovementioned values may be dynamically increased) during the process of formation of the protective coating418.

As shown inFIG.19, the protective coating418of the part400was formed to have the first portion422, the second portion424and a third portion426. The first portion422is connected to the substrate402and the second portion424, and the third portion426is connected to the second portion424and is opposite to the first portion422. The third portion426has a larger atomic ratio of carbon near outer surface of the protective coating418than that of the first portion422near the substrate402.

FIG.20is a chart showing the result of EDS analysis taken along line (L3) ofFIG.19. As shown inFIGS.19and20, the carbon content (i.e., the atomic ratio of carbon) in the protective coating418increases along the line (L3) (e.g., increases in a direction away from the substrate402), and the silicon content (i.e., the atomic ratio of silicon) in the protective coating418decreases in the direction away from the substrate402. In other words, an atomic ratio of silicon is larger than that of carbon near the substrate402. On the contrary, the atomic ratio of silicon is smaller than that of carbon near the outer surface of the protective coating418away from the substrate402. More specifically, the atomic ratio of silicon is larger than 55% while that of carbon is smaller than 45% near the substrate402and the atomic ratio of carbon is about 70% while that of silicon is about 30% near the outer surface of the protective coating418. The average relative content of silicon to carbon in the protective coating418is near two-thirds (i.e., Si:C=40:60). The curve of silicon element and the curve of carbon intersect at a point less than one half of the distance from the substrate402. As a result, the carbon content as a whole would be larger than the silicon content as a whole in the protective coating418.

In some embodiments, the relative content of silicon to carbon in the protective coating418(i.e., silicon carbide) ranges from two-thirds to one-and-a-half, but other ranges are also possible based on practical requirements.

FIG.21is the result of XRD analysis of the surface of the protective coating418shown inFIG.19. The protective coating418at least contains c-Si (111), c-Si (220),3C-SiC such as β-SiC (111) (i.e., crystalline cubic SiC).

With reference toFIGS.22and25,FIG.22shows a comparative embodiment of a bare silicon wafer substrate20, andFIG.23shows the silicon carbide compound film16produced by the present invention.FIGS.22and23show a cross-sectional microstructure of the bare silicon wafer20and the embodiment of the present invention after 200 seconds of plasma etching in a SF6atmosphere.FIG.22shows that an etching depth of the bare silicon wafer is 1.15 μm, while the etching depth of the present invention is only 0.37 μm inFIG.23. The present invention has an etching rate that is 3.1 times slower than that of the bare silicon wafer proving improved erosion resistance ability to the SF6atmosphere.

FIG.24shows a comparative embodiment of a bare silicon wafer, andFIG.25shows the silicon carbide compound film16produced by the present invention. This test compares the cross-sectional microstructure of the bare silicon wafer and the embodiment of the present invention after 200 seconds of plasma etching in a SF6and Cl2atmosphere.FIGS.24and25show that the etching depth of the bare silicon wafer is 11.85 μm, while the etching depth of the embodiment of the present invention is only 0.61 μm. The present invention has an etching rate that is 19.4 times slower than that of the bare silicon wafer proving an improved erosion resistance ability to the SF6and Cl2atmosphere.

FromFIGS.22to25, the silicon carbide compound film16produced by the present invention has a plasma etching rate that is ten times slower than that of the bare silicon wafer in a fluorine-containing or fluorine-containing and chlorine-containing mixing plasma etching atmosphere, indicating its plasma-resistant capability. Therefore, the silicon carbide compound film16has the effectiveness of surface modification of various components inside plasma etching equipment, thereby increasing their lifespan, preventing chamber contamination, and improving wafer characteristics and yield.

In the aforementioned embodiments, the protective coating418may have a crystalline ratio ranging from 0% to 100%. In other embodiments with higher process temperature or an annealing temperature up to 700° C., the crystalline ratio may be up to 100%. That is, other ranges are also possible based on practical requirements. The crystalline ratio of the protective coating418in accordance with some embodiments of this disclosure may range from 0% to 5%, from 5, to 10%, from 10% to 15%, from 15% to 17%, from 17% to 20%, from 20% to 25%, from 25 to 30%, from 35% to 40%, from 40% to 45%, from 45 to 50%, from 50% to 55%, from 55% to 60%, or other ranges of values, such as 80% when the process temperature or an annealing temperature up to 600° C.

FIG.26is a high resolution transmission electron microscope (HRTEM) image of the sample inFIG.15taken by JEOL Model JEM-2100F. Moreover,FIG.27shows the corresponding diffraction pattern of the example as shown inFIG.15. The detected position shown inFIGS.26and27is 1 μm deep from the outer surface of protective coating418as shown inFIG.15. The circles formed by white dots represent the area of crystalline and the crystalline ratio was calculated to be 5% from the result ofFIG.26.

FIG.28is an HRTEM image of the sample inFIG.16taken by JEOL Model JEM-2100F. Moreover,FIG.29shows the corresponding diffraction pattern of the example as shown inFIG.16. The detected position shown inFIGS.28and29is 1 μm deep from the outer surface of protective coating418as shown inFIG.16. The crystalline ratio was calculated to be 0% from the result ofFIG.28, which represents the existence of amorphous SiC.

FIG.30is an HRTEM image of the sample inFIG.19taken by JEOL Model JEM-2100F. Moreover,FIG.31shows the corresponding diffraction pattern of the example as shown inFIG.19. The detected position shown inFIGS.30and31is 1 μm deep from the outer surface of protective coating418as shown inFIG.19. The circles formed by white dots represent the area of crystalline and the crystalline ratio was calculated to be 70% from the result ofFIG.30. As shown inFIG.31, there are three rings in the diffraction pattern inFIG.31. The first ring near the center represents β-SiC (111). The second ring near the first ring represents β-SiC (220). The third ring outermost represents β-SiC (311). That is, except β-SiC (111), the area of crystalline structure further includes β-SiC (220) and β-SiC (311). Compared to XRD, HRTEM can measure nano scale area and the diffraction pattern is more specific to realize the compound of crystalline structures.

Since the silicon surface atomic density of silicon (111) and (100) surfaces are 7.83×1014/cm2and 6.78×1014/cm2, respectively, more silicon fluoride bonds or silicon chloride bonds of etching byproducts are needed to be formed on the silicon (111) surface compared to those on the silicon (100) surface. Therefore, the etch rate of silicon (111) can be lower than that of silicon (100). In other words, the aforementioned embodiments having c-Si (111) also can decrease the etch rate of various etchant gases, such as gaseous CF4, SiF6, Cl2, etc.

Moreover, the etch resistance capability may be higher when the relative content ratio of carbon to silicon as a whole in the protective coating418(i.e., silicon carbide) is larger than 1, such as 1.5, but other ranges larger than one, for example, 1.1, 1.3 or 1.8, are also possible based on practical requirements.

In addition, the resistance of the protective coating418in the aforementioned embodiments can be adjusted to a target value such as the same value as that of substrate402or other values by doping nitrogen element.