Patent Publication Number: US-11658060-B2

Title: SiC material and method for manufacturing same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Phase Application of PCT International Application No. PCT/KR2020/004075, having an International Filing Date of Mar. 25, 2020, which claims priority to Korean Patent Application No. 10-2019-0045602, filed Apr. 18, 2019, each of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a SiC material and a method for manufacturing the same. 
     BACKGROUND ART 
     An existing CVD SiC material is densely formed with large and small crystal grains of 3 μm to 15 μm and an average crystal grain size of 7 μm to 8 μm, thus forming few grain boundaries. Therefore, the thermal conductivity due to the crystal grains is predominant, indicating a high value of thermal conductivity. The high thermal conductivity of such a CVD SiC material is advantageous for heat emission to minimize damage to semiconductor equipment due to high process temperatures used in some semiconductor etching processes. 
     It is required to form a uniform temperature of the wafer since uniform etching of a wafer edge is required to increase a semiconductor chip yield in a semiconductor process using low process temperatures such as a large scale integrated circuit (LSI). When using a conventional high thermal conductivity CVD SiC material in such a process, there is a problem of increasing the temperature non-uniformity in the wafer due to heat loss. 
     DISCLOSURE OF INVENTION 
     Technical Goals 
     The present invention is to solve the problems as described above, and relates to a SiC material which adjusts thermal conductivity by refining the average crystal grain size and can be effectively applied to a semiconductor manufacturing process requiring low temperatures, and a method for manufacturing the SiC material. 
     Problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by one of ordinary skill in the art from the following description. 
     Technical Solutions 
     According to an embodiment of the present invention, it relates to a SiC material including a low thermal conductivity region which has an average crystal grain size of 3.5 μm or less, and is a ( 111 ) plane preferential growth in X-ray diffraction analysis. 
     According to an embodiment of the present invention, the low thermal conductivity region may have an average crystal grain size of 0.5 μm to 3.5 μm. 
     According to an embodiment of the present invention, the low thermal conductivity region may have a diffraction intensity ratio (I) of the X-ray diffraction analysis calculated according to Equation 1 below of 0.5 or less.
 
Diffraction intensity ratio ( I )=(peak intensity of (200) plane+peak intensity of (220) plane+peak intensity of (311) plane)/peak intensity of (111) plane  [Equation 1]
 
     According to an embodiment of the present invention, the low thermal conductivity region may have a diffraction intensity ratio (1) of the X-ray diffraction analysis calculated according to Equation 2 below of 0.5 or less.
 
Diffraction intensity ratio ( I )=(peak intensity of (200) plane+peak intensity of (220) plane)/peak intensity of (111) plane  [Equation 2]
 
     According to an embodiment of the present invention, the diffraction intensity ratio (I) may be 0.001 to 0.3. 
     According to an embodiment of the present invention, the low thermal conductivity region may have a thermal conductivity of 200 W/mk or less. 
     According to an embodiment of the present invention, the low thermal conductivity region may be deposited by a CVD method. 
     According to an embodiment of the present invention, the SiC material may be a material of a part used in a plasma processing apparatus for manufacturing a semiconductor non-memory. 
     According to an embodiment of the present invention, the SiC material may be a ring for mounting a wafer, and the low thermal conductivity region may be formed in a region where the wafer is mounted. 
     According to an embodiment of the present invention, the low thermal conductivity region may have a temperature deviation of 1° C. or less. 
     According to an embodiment of the present invention, the low thermal conductivity region may be formed to 50% or more and less than 100% of the area of the SiC layer. 
     According to an embodiment of the present invention, the SiC layer may have a thickness of 2 mm or more. 
     According to an embodiment of the present invention, it relates to a SiC material including a SiC layer which has an average crystal grain size of 3.5 μm or less, and is a ( 111 ) plane preferential growth in X-ray diffraction analysis. 
     According to an embodiment of the present invention, the SiC layer may have a thermal conductivity of 200 W/mk or less. 
     According to an embodiment of the present invention, the SiC layer may have a diffraction intensity ratio (I) of the X-ray diffraction analysis calculated according to Equation 1 below of 0.5 or less. 
     
       
         
           
             
               
                 
                   
                     Diffraction 
                     ⁢ 
                     
                         
                     
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                     intensity 
                     ⁢ 
                     
                         
                     
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                     ratio 
                     ⁢ 
                     
                         
                     
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                       ( 
                       I 
                       ) 
                     
                   
                   = 
                   
                     
                       
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                             intensity 
                             ⁢ 
                             
                                 
                             
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                       111 
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                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     According to an embodiment of the present invention, the SiC layer may have a diffraction intensity ratio (I) of the X-ray diffraction analysis calculated according to Equation 2 below of 0.5 or less. 
     
       
         
           
             
               
                 
                   
                     Diffraction 
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                   = 
                   
                     
                       
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                       ( 
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                   [ 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     2 
                   
                   ] 
                 
               
             
           
         
       
     
     According to an embodiment of the present invention, the SiC layer may have a thickness of 2 mm or more. 
     According to an embodiment of the present invention, it relates to a method for manufacturing a SiC material, the method including the steps of: preparing a substrate; and forming a SiC layer on the substrate using a CVD method, in which the SiC layer has a low thermal conductivity region formed in at least a portion thereof, the low thermal conductivity region which has an average crystal grain size of 3.5 μm or less, and is a ( 111 ) plane preferential growth in X-ray diffraction analysis. 
     Effects 
     The present invention may provide a CVD SiC material which exhibits low thermal conductivity properties compared to a conventional CVD SiC material by adjusting the average crystal grain size. 
     The present invention may provide a CVD SiC material applicable to a semiconductor process requiring low process temperatures in an economical manner since thermal conductivity may be adjusted in a simple manner according to changes in process conditions. 
     Since a uniform temperature distribution may be formed in the wafer in a microprocess semiconductor manufacturing process such as LSI, the present invention may achieve uniform etching to the wafer edge, and may improve wafer yield and quality. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1 A  shows an SEM image of the SiC material manufactured in Exemplary Embodiment 2 of the present invention. 
         FIG.  1 B  shows XRD pattern analysis results of the SiC material manufactured in Exemplary Embodiment 2 of the present invention. 
         FIG.  2 A  shows an SEM image of the SiC material manufactured in Comparative Embodiment 1 of the present invention. 
         FIG.  2 B  shows XRD pattern analysis results of the SiC material manufactured in Comparative Embodiment 1 of the present invention. 
         FIG.  3    shows measurement results of average crystal grain sizes and thermal conductivities of the SiC materials manufactured in Exemplary Embodiments and Comparative Embodiments of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes may be applied to the embodiments, the scope of rights of the patent application is not restricted or limited by such embodiments. It should be understood that all modifications, equivalents and substitutes for the embodiments are included within the scope of the rights. 
     Terms used in the embodiments have been used for the purpose of explanation only, and the terms should not be interpreted as an intention of limiting the explanation. An expression of the singular number includes an expression of the plural number unless clearly defined otherwise in the context. In the present specification, it should be understood that a term such as “comprises” or “having” is used to specify existence of a feature, a number, a step, an operation, an element, a part, or a combination thereof described in the specification, but it does not preclude the possibility of the existence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof. 
     Unless otherwise defined, all terms, including technical or scientific terms, used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which embodiments pertain. Terms, such as those defined in commonly used dictionaries, should be interpreted as having meanings that are consistent with those in the context of the related art but are not interpreted as having ideal or excessively formal meanings unless clearly defined in the present application. 
     Further, in the description with reference to the accompanying drawings, the same elements are assigned the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In the description of the embodiments, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiments, the detailed description thereof will be omitted. 
     The present invention relates to a SiC material, and according to an embodiment of the present invention, the SiC material may include a SiC layer having a low thermal conductivity region formed in at least a portion thereof. The SiC layer may provide a region having a uniform temperature distribution by forming the low thermal conductivity region. The low thermal conductivity region may be formed to 50% or more and less than 100% of an area of the SiC layer. 
     The low thermal conductivity region may be formed by adjusting the average crystal grain size in the SiC layer. For example, it is possible to finely adjust the average crystal grain size and lower the thermal conductivity by adjusting the growth rate through process changes such as process temperature, raw material supply rate, etc. in the deposition process by the CVD method. That is, the average crystal grain size of the low thermal conductivity region is reduced to increase the formation of grain boundaries so that a structure that suppresses heat transfer may be formed, and low thermal conductivity may be exhibited. 
     The average crystal grain size of the low thermal conductivity region may have a lower size than an average crystal grain size or a maximum crystal grain size of the entire SiC layer. For example, the low thermal conductivity region may have an average crystal grain size of: 3.5 μm or less; 0.01 μm to 3.5 μm; 0.1 μm to 3.5 μm; or 0.5 μm to 3.5 μm. When the low thermal conductivity region is included within the range of the average crystal grain size, low thermal conductivity may be formed, and a uniform temperature distribution may be formed in the low thermal conductivity region. The crystal grain size may mean an area, a length, a particle size, a diameter, etc. of a crystal grain. 
     The low thermal conductivity region is a ( 111 ) plane preferential growth in X-ray diffraction analysis, and may form a low thermal conductivity region which may improve stability and lifespan of the SiC material in a plasma environment or the like according to the ( 111 ) plane preferential growth. That is, a relatively high ( 111 ) plane preferential growth compared to a region except for the low thermal conductivity region in the SiC layer may be achieved. 
     For example, a diffraction intensity ratio (I) of X-ray diffraction analysis according to Equation 1 and/or Equation 2 below may be represented. The diffraction intensity ratio (I) of the ray diffraction analysis may be: 0.5 or less; 0.001 to 0.3 or less; 0.01 to 0.3; or 0.1 to 0.2. 
     
       
         
           
             
               
                 
                   
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                     Equation 
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                     1 
                   
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                     2 
                   
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     The low thermal conductivity region may have a thermal conductivity lower than a maximum thermal conductivity or an average thermal conductivity of the entire SiC layer, and may have a thermal conductivity of, for example, 200 W/mk or less; 20 W/mk to 200 W/mk; or 80 to 200 W/mk. The low thermal conductivity region may have a temperature deviation of: 1° C. or less; 0.8° C. or less; or 0.5° C. or less. When the low thermal conductivity region is included within the thermal conductivity and temperature deviation ranges, a uniform temperature distribution may be exhibited, and product quality, yield, etc. may be improved in the semiconductor manufacturing process. 
     The SiC layer may be formed to a thickness of: 2 mm or more; 10 mm or more; or 50 mm or more, and may have a single layer or multiple layers deposited therein by the CVD method. When forming the multiple layers, layers of the same or different configurations may be formed, and components and thicknesses of the multiple layers, average crystal grain sizes and thermal conductivities of the low thermal conductivity regions, growth directions of the crystal planes, etc. may be the same or different. At this time, when the low thermal conductivity region is formed in the SiC layer forming the multiple layers, the effect of blurring the clear boundary between the layers may be expected by reducing the resistance deviation and making the structure uniform. 
     The SiC material is a material of a part used in a plasma processing apparatus for semiconductor manufacturing, and may be, for example, a ring for mounting a wafer for mounting the wafer applied to a non-memory manufacturing process that requires low process temperatures, that is, an LSI semiconductor manufacturing process. In the SiC material, a low thermal conductivity region may be formed in a portion requiring the formation of a uniform temperature distribution, and a low thermal conductivity region may be formed in a region which is in direct contact with the wafer in the ring for mounting the wafer. Since this forms a uniform temperature distribution over the entire wafer in the LSI semiconductor manufacturing process, uniform etching to the wafer edge is possible, and yield and quality of the semiconductor chip may be improved. 
     According to an embodiment of the present invention, it relates to a SiC material including a SiC layer having low thermal conductivity properties. 
     The SiC layer may have an average crystal grain size of: 3.5 μm or less; 0.01 μm to 3.5 μm; 0.1 μm to 3.5 μm; or 0.5 μm to 3.5 μm. When the SiC layer is included within the range of the average crystal grain size, low thermal conductivity may be formed, and a uniform temperature distribution may be formed. 
     The SiC layer may have a thermal conductivity of: 200 W/mk or less; 20 W/mk to 200 W/mk; or 80 to 200 W/mk. Alternatively, the SiC layer may have a temperature deviation of: 1° C. or less; 0.8° C. or less; or 0.5° C. or less. When the SiC layer is included within the thermal conductivity and temperature deviation ranges, a uniform temperature distribution may be exhibited, and product quality, yield, etc. may be improved in the semiconductor manufacturing process. 
     The SiC layer is a ( 111 ) plane preferential growth in X-ray diffraction analysis, and may provide a stable low thermal conductivity material in a plasma environment according to the ( 111 ) plane preferential growth. For example, a diffraction intensity ratio (I) of X-ray diffraction analysis according to Equation 1 and/or Equation 2 below may be represented. The diffraction intensity ratio (I) of the X-ray diffraction analysis may be: 0.5 or less; 0.001 to 0.3 or less; 0.01 to 0.3; or 0.1 to 0.2. 
     
       
         
           
             
               
                 
                   
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                   [ 
                   
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     The SiC layer may be formed to a thickness of: 2 mm or more; 10 mm or more; or 50 mm or more, and may have a single layer or multiple layers deposited therein by the CVD method. When forming the multiple layers, the same or different layers may be formed, and components and thicknesses of the layers, average crystal grain sizes and thermal conductivities of the low thermal conductivity regions, growth directions of the crystal planes, etc. may be the same or different. At this time, when the low thermal conductivity region is formed in the SiC layer forming the multiple layers, the effect of blurring the clear boundary between the layers may be expected by reducing the resistance deviation and making the structure uniform. 
     The present invention provides a method for manufacturing a SiC material according to the present invention, and the method according to an embodiment of the present invention may include the steps of: preparing a substrate; and forming a SiC layer on the substrate by using the CVD method. 
     The step of preparing the substrate may be applied without limitation as long as it is applicable to the manufacturing of the SiC layer or the SiC material. 
     In the step of forming the SiC layer on the substrate by using the CVD method, the entire SiC layer may have low thermal conductivity properties, or a low thermal conductivity region may be formed in at least a portion of the SiC layer. That is, the thermal conductivity may be lowered by adjusting CVD method deposition process conditions, for example, process temperature, raw material supply flow rate, etc., thereby finely adjusting the average crystal grain size through control of the growth rate, and increasing the grain boundary (for example, 30% or more). 
     The process temperature may be appropriately selected in order to adjust the average crystal grain size, and may be, for example, a temperature lower than the deposition temperature of the SiC layer by a conventional CVD method or a temperature lower than the maximum or average process temperature of the step of forming the SiC layer. The raw material supply flow rate may be appropriately selected in order to adjust the average crystal grain size, and for example, may be: 90% or less; 60% or less; or 50% or less of the supply flow rate applied during deposition of the SiC layer by the conventional CVD method or the maximum or average supply flow rate of the step of forming the SiC layer. 
     The step of forming the SiC layer on the substrate by using the CVD method may be a growth rate lower than the growth rate applied during deposition of the SiC layer by the conventional CVD method, or a growth rate lower than the maximum or average growth rate of the step of forming the SiC layer. 
     Exemplary Embodiment 1 
     A SiC layer (2 mm thick) was deposited on a substrate by the CVD method to manufacture a CVD SiC material with a SiC layer formed therein having a crystal grain size of 0.5 μm to 3 μm (average crystal grain size: 0.82 μm, ASTM E112 measurement method applied). 
     Exemplary Embodiment 2 
     A SiC layer (2 mm thick) was deposited on a substrate by the CVD method to manufacture a CVD SiC material with a SiC layer formed therein having a crystal grain size of 0.5 μm to 3 μm (average crystal grain size: 2.2 μm, ASTM E112 measurement method applied). 
     Comparative Embodiment 1 
     A SiC layer (2 mm thick) was deposited on a substrate by the CVD method to manufacture a CVD SiC material with a SiC layer formed therein having a crystal grain size of 3 μm to 15 μm (average crystal grain size: 7.4 μm, ASTM E112 measurement method applied). 
     Comparative Embodiment 2 
     A SiC layer (2 mm thick) was deposited on a substrate by the CVD method to manufacture a CVD SiC material with a SiC layer formed therein having a crystal grain size of 3 μm to 15 μm (average crystal grain size: 9.07 μm, ASTM E112 measurement method applied). 
     Evaluation Embodiment 1 
     After measuring SEM and XRD of the CVD SiC materials of Exemplary Embodiment 2 and Comparative Embodiment 1, the measured SEM and XRD are shown in  FIG.  1    ( FIGS.  1 (A) and  1 (B) , Exemplary Embodiment 2) and  FIG.  2    ( FIGS.  2 (A) and  2 (B) , Comparative Embodiment 1). 
     The XRD was measured in a measurement range of 10 to 80°, at a scan speed of 10, and at a scan step of 0.05 by using “Rigaku DMAX200” equipment. Looking at  FIG.  1   , it can be confirmed that the CVD SiC material of Exemplary Embodiment 2 has a crystal grain size range of 0.5 μm to 3 μm, and the ( 111 ) plane is preferentially grown so that the diffraction intensity ratio (I) according to Equation 1 is 0.01. 
     Meanwhile, since the CVD SiC material of Comparative Embodiment 1 is a commonly used material, has a crystal grain size of 3 to 15 μm (average 7.4 μm), and the ( 111 ) plane is preferentially grown, but peak intensities of ( 200 ), ( 220 ), and ( 311 ) planes are 5,000 cps or more, it can be confirmed that the CVD SiC material is out of the range of the diffraction intensity ratio (I) according to Equation 1 of the present invention. 
     Evaluation Embodiment 2 
     After measuring thermal conductivities of the CVD SiC materials manufactured in Exemplary Embodiments and Comparative Embodiments, the measured thermal conductivities thereof are shown in  FIG.  3    and Table 1. The crystal grain sizes of the CVD SiC materials were measured by the ASTM E122 method. The thermal conductivities were measured by preparing specimens based on the KS standard using sorting equipment having a model name of Light Flash Apparatus (LFA) 447 NanoFlash manufactured by NETZSCH company. 
     Looking at  FIG.  3   , it can be confirmed that the thermal conductivities are increased according to the increase of the crystal grain sizes by exhibiting low thermal conductivity properties when the average crystal grain size is 2.2 μm or less, thermal conductivities exceeding 200 W/mK when the average crystal grain size is 5 μm or more, and thermal conductivities exceeding 300 W/mK when the average crystal grain size is 8 μm or more. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Exemplary 
                 Exemplary 
                 Comparative 
                 Comparative 
               
               
                   
                 Embodiment 
                 Embodiment 
                 Embodiment 
                 Embodiment 
               
               
                   
                 1 
                 2 
                 1 
                 2 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Thermal 
                 94 
                 153 
                 247 
                 329 
               
               
                 conductivity 
                   
                   
                   
                   
               
               
                 (W/mK) 
                   
                   
                   
                   
               
               
                 Average crystal 
                 0.82 
                 2.2 
                 7.4 
                 9.07 
               
               
                 grain size (μm) 
               
               
                   
               
            
           
         
       
     
     The present invention may provide a CVD SiC material which is refined to an average crystal grain size of 3 μm or less by reducing the growth rate compared to Comparative Embodiments through a process change in the CVD deposition process, and which has a low thermal conductivity of 80 W/mK to 200 W/mK by inducing a ( 111 ) preferential growth. Although the embodiments have been described with reference to the limited drawings as described above, one of ordinary skill in the art may apply various technical modifications and variations based on the aforementioned descriptions. For example, appropriate results can be achieved although described techniques are performed in order different from a described method, and/or described elements are joined or combined in a form different from the described method, or replaced or substituted by other elements or equivalents. 
     Therefore, other implementations, other embodiments, and equivalents to the patent claim scope also belong to the scope of the claims described later.