Patent Publication Number: US-2022216085-A1

Title: Electrostatic chuck and method for manufacturing the same

Description:
This application claims the benefit of Taiwan application Serial No. 110100634, filed Jan. 7, 2021, the subject matter of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The technical field relates to an electrostatic chuck and a method for manufacturing the same, 
     BACKGROUND 
     In recent years, the development of the semiconductor industry is getting more and more important. In the various semiconductor related equipment, the electrostatic chuck is one of the most widely used system components. For example, in each of the semiconductor processes (such as the deposition process, the ion implantation process, the dry etching process and the photolithography process), the electrostatic chuck is used to hold, fix and move the wafer. However, the high temperature and the long duration of vacuum state in some semiconductor processes may cause the clamping force of the electrostatic chuck to deteriorate and may also shorten the lifespan of the electrostatic chuck or may even interrupt the semiconductor process. Therefore, it has become a prominent task for the industry to provide an electrostatic chuck capable of preventing the above problems. 
     SUMMARY 
     According to one embodiment of the present disclosure, an electrostatic chuck is provided. The electrostatic chuck includes a base and an insulating layer, an electrode layer, a first dielectric layer and a second dielectric layer sequentially stacked on the base. The first dielectric layer is formed of aluminum oxide (Al 2 O 3 ) or aluminum nitride (AlN). The material of the second dielectric layer is different from that of the first dielectric layer, and the second dielectric layer includes titanium a group IVA element and oxygen. 
     According to another embodiment of the present disclosure, a method for manufacturing an electrostatic chuck is provided. The method includes the following steps. Firstly, a base is provided. Next, an insulating layer and an electrode layer are sequentially formed and stacked on the base. Then, a first dielectric layer is formed on the insulating layer by using a thermal spraying process. After that, a second dielectric layer is formed on the first dielectric layer by using a sol-gel process. The first dielectric layer is formed of aluminum oxide (Al 2 O 3 ) or aluminum nitride (AlN). The material of the second dielectric layer is different from that of the first dielectric layer, and the second dielectric layer includes titanium, a group IVA element and oxygen. 
     The above and other aspects of the disclosure will become better understood with regard to the following detailed description of the preferred but non-limiting embodiment(s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an electrostatic chuck according to an embodiment of the present disclosure. 
         FIGS. 2A-2C  are processes of a method for manufacturing an electrostatic chuck according to an embodiment of the present disclosure. 
         FIGS. 3A-3C  are processes of a manufacturing method corresponding to a part of the second dielectric layer of  FIG. 2A . 
         FIG. 4  is a schematic diagram of an assembly equipment for testing the electrostatic clamping force of an electrostatic chuck. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     A number of implementations of the present disclosure are disclosed below with reference to accompanying drawings. It should be noted that the structure and description of the implementations of the present disclosure are for exemplary purpose only, not for limiting the scope of protection of the present disclosure. Although the present disclosure does not illustrate all possible embodiments, a person ordinary skilled in the technology field can make necessary modifications or adjustments to fit actual needs without departing from the spirit and scope of the present disclosure. 
     Moreover, similar/identical designations are used to indicate similar/identical elements of the embodiments. Also, the accompanying drawings are simplified such that the embodiments can be more dearly described, and dimension scales used in the accompanying drawings are not based on actual proportion of the product, and therefore are not for limiting the scope of protection of the present disclosure. 
       FIG. 1  is a cross-sectional view of an electrostatic chuck  10  according to an embodiment of the present disclosure. 
     Refer to  FIG. 1 . The electrostatic chuck  10  can be used to hold, fix or move an object  12 . The object  12  such as a wafer, glass or other suitable objects. According to an embodiment, the electrostatic chuck  10  comprises a base  100  and an insulating layer  110 , an electrode layer  120 , a first dielectric layer  130  and a second dielectric layer  140  sequentially stacked (such as vertical stacking) on the base  100 . The electrode layer  120  comprises a first electrode  120   a  and a second electrode  120   b . In an embodiment, a positive voltage and a negative voltage are respectively applied to the first electrode  120   a  and the second electrode  120   b  to make the electrostatic chuck  10  generate induced charges to hold, fix or move the object  12 . In other embodiment, a negative voltage and a positive voltage are respectively applied to the first electrode  120   a  and the second electrode  120   b.    
     In some embodiments, the insulating layer  110  has an upper surface  110   s  with which the electrode layer  120  and the first dielectric layer  130  can directly contact. The extending direction of the upper surface  110   s  is parallel to the first direction D 1 , and the normal direction of the upper surface  110   s  is parallel to the second direction D 2 . The electrode layer  120  is interposed between the insulating layer  110  and the first dielectric layer  130 , and the first dielectric layer  130  is interposed between the electrode layer  120  and the second dielectric layer  140 . That is, the second dielectric layer  140  and the electrode layer  120  are separated by the first dielectric layer  130 . The first dielectric layer  130  and the second dielectric layer  140  overlap with each other in the normal direction of the upper surface  110   s . The second dielectric layer  140  is closer to the object  12  than the first dielectric layer  130 . In some embodiments, a part of the second dielectric layer  140  can be permeated to the gaps of the first dielectric layer  130 , therefore a part of the second dielectric layer  140  can overlap the first dielectric layer  130  in a direction parallel to the upper surface  110   s  (such as the first direction D 1 ) as shown in  FIG. 30 . According to some embodiments, the first dielectric layer  130  has a thickness in a range of 20-500 μm, and the second dielectric layer  140  has a thickness in a range of 0.1-50 μm or 0.5-20 μm. If the second dielectric layer  140  is too thin, the second dielectric layer  140  will be unable to improve the electrostatic clamping force. If the second dielectric layer  140  is too thick, the second dielectric layer  140  will have free electrons during the process of generating induced charges. When the free electrons and the clamped object (such as silicon wafer) are conducted, damage or negative influence may occur. 
     In some embodiments, the base  100  may include ceramics and metal. The insulating layer  110  may include an oxide. The first dielectric layer  130  may be formed of aluminum oxide (Al 2 O 3 ) or aluminum nitride (AlN), which has excellent insulating property to avoid the electrode layer  120  being short-circuited. Besides, aluminum oxide and aluminum nitride have a wide range of application. The material of the second dielectric layer  140  is different from that of the first dielectric layer  130 , and the second dielectric layer  140  may include titanium, a group IVA element and oxygen. In some embodiments, the second dielectric layer  140  does not include aluminum oxide and aluminum nitride. To be more precisely, the second dielectric layer  140  is substantially consisted of titanium, at least one element of the IVA group and oxygen. In some embodiments, the second dielectric layer  140  is substantially consisted of titanium and the oxides of the group IVA element, or is substantially consisted of the oxide of titanium and a group IVA element, or the second dielectric layer  140  is substantially consisted of the oxide of titanium and the oxide of the group IVA element. The group IVA elements include carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), or a combination thereof. In the second dielectric layer  140 , titanium and the sum of the titanium and the group IVA element have a molar % (e.g. Ti/(Ti+IVA)) of 5.0% to 95.0%. That is, if the mole number of titanium is M1 and the mole number of the group IVA element is M2, then the molar % of titanium is expressed as: (mol/mol)%=M1/(M1+M2)%. If the molar % of titanium is too low, this implies that the second dielectric layer  140  does not improve electrostatic clamping force much. If the molar % of titanium is too high, this implies that the second dielectric layer  140  will generate effects such as chalking, cracking, or peeling during the film forming process. In an embodiment, the second dielectric layer  140  may include one of the group IVA elements, but the present disclosure is not limited thereto. In other embodiments, the second dielectric layer  140  may include two of the group IVA elements. For example, the second dielectric layer  140  may include titanium dioxide and silicon dioxide, and has a composition of (SiO 2 ) X (TiO 2 ) 1-X , wherein 0.05&lt;X&lt;0.95, and the structure is expressed as following Formula 1: 
     
       
         
         
             
             
         
       
     
     The electrostatic chuck  10  of the present disclosure is a Coulomb-type electrostatic chuck, and the clamping force of the electrostatic chuck  10  is proportional to the square of the dielectric constant (the k value) of the dielectric material (that is, the first dielectric layer  130  and the second dielectric layer  140 ) used in the electrostatic chuck  10 . In an embodiment of the present disclosure, the first dielectric layer  130  includes aluminum oxide; the second dielectric layer  140  includes titanium and therefore has a dielectric constant larger than that of the first dielectric layer  130 . According to a comparison example, it only has a first dielectric layer formed of aluminum oxide, but does not have a second dielectric layer (hereinafter referred as comparison example A). In comparison to the comparison example A, the second dielectric layer  140  of the present disclosure has a dielectric constant larger than that of the first dielectric layer  130 , such that the overall dielectric constant of the dielectric material of the electrostatic chuck  10  can be increased, the electrostatic chuck  10  of the present disclosure can provide a larger clamping force. 
     In an embodiment, the first dielectric layer  130  can be formed by using a thermal spraying process, and the second dielectric layer  140  can be formed by using a sol-gel process. Since different manufacturing processes are used, the porosity of the first dielectric layer  130  is larger than the porosity of the second dielectric layer  140 . For example, the porosity of the first dielectric layer  130  can be in a range of 0.5-15%. The porosity of the second dielectric layer  140  can be smaller than 0.5%. In other words, the structure of the second dielectric layer  140  is denser than the structure of the first dielectric layer  130 . In comparison example A, the electrostatic chuck only has the first dielectric layer with a larger porosity, and after the electrostatic chuck is performed with a semiconductor process at a high temperature for a long duration of vacuum state, the water moisture which originally was absorbed in the gaps of the first dielectric layer is evaporated. Since the dielectric constant of water is lamer than the dielectric constant of aluminum oxide, the overall dielectric constant of the electrostatic chuck decreases, and the electrostatic chucking force (that is, the damping force) also decreases. Unlike comparison example A, in the present disclosure, the second dielectric layer  140  of the electrostatic chuck  10  covers the first dielectric layer  130 , not only sealing the gaps of the first dielectric layer  130  to avoid the evaporation of the water moisture, but further resolving the decay of the electrostatic pressure which occurs at a high temperature for a long duration of vacuum state. 
     In comparison example B, in order to increase the clamping force of the electrostatic chuck, an inorganic material with a large dielectric constant (such as titanium dioxide or zirconium dioxide) is directly doped in the first dielectric layer formed of aluminum oxide, In the said method, the overall dielectric constant of the first dielectric layer is directly increased. If the concentration of the inorganic material with a large dielectric constant doped in the first dielectric layer is too high, the electrostatic chuck may generate conduction between electrodes and electrodes, between electrodes and the base, and between electrodes and the to-be-clamped object. Unlike comparison example B, in the present disclosure, the second dielectric layer  140  of the electrostatic chuck  10  is additionally formed on the first dielectric layer  130  and the insulating ability of the first dielectric layer  130  is not decreased, such that the dielectric constant of the overall electrostatic chuck  10  can be increased and the effect of electrostatic clamping force can be enhanced without triggering the said conduction. 
       FIGS. 2A-2C  are processes of a method for manufacturing an electrostatic chuck  10  according to an embodiment of the present disclosure, 
       FIGS. 3A-3C  are processes of a manufacturing method corresponding to a part C 1  of the second dielectric layer  140  of  FIG. 2B . 
     Refer to  FIG. 2A . A base  100  is provided, and an insulating layer  110  and an electrode layer  120  are sequentially formed and stacked on the base  100 . The base  100  can be a metal or ceramic base with pattern, circuit, cooling water and vent pipe structure designed on the surface. The insulating layer  110  can be formed by using a thermal spraying process. The electrode layer  120  is formed by using a screen printing process or a thermal spraying process. The electrode layer  120  comprises a first electrode  120   a  and a second electrode  120   b . Then, a first dielectric layer  130  is formed on the insulating layer  110  by using a thermal spray process. The first dielectric layer  130  includes aluminum oxide (Al 2 O 3 ). Thermal spraying process includes powder flame spraying, atmospheric plasma spraying, vacuum plasma spraying or arc spraying. 
     Refer to  FIGS. 2B-2C . A second dielectric layer  140  is formed on the first dielectric layer  130  by using a sol-gel process. As indicated in  FIG. 2B , the dielectric material  140 ′ in a liquid state (sol state) is coated on the first dielectric layer  130 . The material of the dielectric material  140 ′ is different from the material of the first dielectric layer  130 , and includes titanium, a group IVA element and oxygen. Then, the dielectric material  140 ′ in a sol state is cured and baked to form a second dielectric layer  140  in a solid state (gel state) as shown in  FIG. 2C . 
     Refer to both FIGS,  2 B and  3 A. The first dielectric layer  130  includes a plurality of gaps G 1 , the dielectric material  140 ′ in a liquid state (sol state) is coated on the first dielectric layer  130  having gaps G 1 . Then, referring to  FIG. 3B , the dielectric material  140 ′ in a liquid state (sol state) is permeated into the gaps G 1 . Referring to  FIG. 3C , after the curing and baking steps are performed, the dielectric material  140 ′ in a sol state forms a second dielectric layer  140  in a solid state (gel state), and a part of the second dielectric layer  140  overlaps the first dielectric layer  130  in the first direction D 1 . Since a part of the second dielectric layer  140  is embedded in the first dielectric layer  130 , the second dielectric layer  140  and the first dielectric layer  130  are well adhered and the second dielectric layer  140  will not be easily peeled from the first dielectric layer  130 . 
     In comparison to the comparison example in which the second dielectric layer is formed by using a thermal spraying process, in the present disclosure, the second dielectric layer  140  is formed by using a sol-gel process and therefore has a smaller porosity (such as smaller than 0.5%), the structure has a larger density, and water moisture is less likely evaporated under the conditions of high temperature and vacuum state. Thus, the drop of the electrostatic pressure caused by the removal of water moisture can be avoided. 
     Generally speaking, the coating solution LT, which contains the oxide of titanium (such as titanium dioxide) and is manufactured by using a sol gel method, may easily form large particles and generate phenomena such as precipitation or colloidization. The stability of the coating solution LT is insufficient. Furthermore, after the coating solution LT is coated on the first dielectric layer disposed on the surface of the electrostatic chuck and then is cured and baked to form a film, powders may be generated or the film layer may be peeled off, making the formation and stability of the film unsatisfactory. In comparison to the comparison example in which the second dielectric layer includes titanium and oxygen but not group IVA elements, in the present disclosure, the second dielectric layer  140  includes titanium, oxygen and a group IVA element, which can modify the structure of the oxide of titanium and make the molecular size controllable, such that the coating solution (that is, the dielectric material  140  in a liquid state) can have better stability, and during the curing and baking step, the second dielectric layer  140  is less likely to generate powders or become peeled off, and therefore has a better performance in film formation. 
     The electrostatic chucks according to examples 1˜6 and comparison examples 1˜4 are exemplified below, and the damping force and film formation of each electrostatic chuck are tested. The structure of the electrostatic chuck of each of examples 1˜6 is identical to the structure of the electrostatic chuck  10  of  FIG. 1 , and the manufacturing process of the electrostatic chuck of examples 1˜6 is identical to that of the electrostatic chuck  10  of  FIGS. 2A-2C . That is, in examples 1˜6, the electrostatic chuck comprises a base and an insulating layer, an electrode layer, a first dielectric layer and a second dielectric layer sequentially stacked on the base. The first dielectric layer is formed by using a thermal spray process, the material of the first dielectric layer includes aluminum oxide, and the first dielectric layer has a thickness in a range of 100 μm-110 μm; and the second dielectric layer is formed by using a sol gel method. The structure of the electrostatic chuck as indicated in comparison examples 2˜4 is similar to the structure of the electrostatic chuck  10 . That is, the electrostatic chuck in comparison examples 2˜4 also includes a first dielectric layer and a second dielectric layer, the first dielectric layer is formed by using a thermal spray process, the material of the first dielectric layer includes also aluminum oxide, and the first dielectric layer has a thickness in a range of 100 μm-110 μm. In examples 1˜6 and comparison examples 2˜4, the material or/and usage of the second dielectric layer are not the same. In embodiments 1˜4, the second dielectric layer includes titanium, oxygen and silicon. In example 5, the second dielectric layer includes titanium, oxygen, silicon and carbon. In example 6, the second dielectric layer includes titanium, oxygen and tin. The structure of the electrostatic chuck of comparison example 1 is different from the structure of the electrostatic chuck  10  in that the electrostatic chuck of comparison example 1 does not include a second dielectric layer, but the first dielectric layer is also formed by using a thermal spray process, the material of the first dielectric layer also includes aluminum oxide, and the first dielectric layer has a thickness in a range of 100 μm-110 μm. Details of the method for manufacturing the second dielectric layer of the electrostatic chuck of each of examples 1˜6 and comparison examples 2˜4 are disclosed below. 
     EXAMPLE 1 
     36 g of tetraethoxysilane (TEOS), 90 g of methyltriethoxysilane (MTES), 18 g of (3-glycidyloxypropyl) trimethoxysilane (GPTMS) and 36 g of 0.1N nitric add solution are mixed, and then are stirred and reacted at room temperature for 16 hours, then the mixed solution is reacted at 60° C. for 8 hours to form a solution A 1 . 
     2.76 g of 65-70% nitric acid and 7.6 g of ethanol are added to 10 g of deionized water, then the mixed solution is stirred for 20 minutes to form a catalytic solution T1. 8.5 g of titanium (IV)-butoxide (TBO) and 27.6 g of ethanol are mixed and stirred for 20 minutes, then the mixed solution is slowly added to the catalytic solution T 1 , and together is stirred at room temperature for 60 minutes to form a solution B 1 . 
     20 g of solution A 1  (that is, silicon-containing solution) and 5 g of solution B 1  (that is, titanium-containing solution) are mixed and then the mixed solution is stirred at room temperature for 16 hours to obtain a titanium silicon composite solution D 1 . Then, the titanium silicon composite solution D 1  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     EXAMPLE 2 
     A solution A 2  and a solution B 2  are respectively formed by using the same method for manufacturing the solution A 1  and the solution B 1  of example 1. 
     35g of solution A 2  (that is, silicon-containing solution) and 15 g of solution B 2  (that is, titanium-containing solution) are mixed and then the mixed solution is stirred at room temperature for 16 hours to obtain a titanium silicon composite solution D 2 . Then, the titanium silicon composite solution D 2  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     EXAMPLE 3 
     A solution A 3  and a solution B 3  are respectively formed by using the same method for manufacturing the solution A 1  and the solution B 1  of example 1. 
     30 g of solution A 3  (that is, silicon-containing solution) and 20 g of solution B 3  (that is, titanium-containing solution) are mixed and then the mixed solution is stirred at room temperature for 16 hours to obtain a titanium silicon composite solution D 3 . Then, the titanium silicon composite solution D 3  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     EXAMPLE 4 
     A solution A 4  and a solution B 4  are respectively formed by using the same method for manufacturing the solution A 1  and the solution B 1  of example 1. 
     20 g of solution A 4  (that is, silicon-containing solution) and 20 g of solution B 4  (that is, titanium-containing solution) are mixed and then the mixed solution is stirred at room temperature for 16 hours to obtain a titanium silicon composite solution D 4 . Then, the titanium silicon composite solution D 4  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     The second dielectric layer of examples 1˜4 may include the structure as indicated in above-mentioned Formula 1. 
     EXAMPLE 5 
     2 g of 3-(trimethoxysilyl)-propylmethacrylate (MSMA) are added to 20 g of n-butanol and then the mixed solution is stirred at room temperature for 30 minutes to form a solution A 5 . 
     27.8 g of titanium (IV)-butoxide are added to 40 g of n-butanol and then the mixed solution is stirred at room temperature for 30 minutes to form a solution B 5 . Then, 60 g of n-butanol, 1.12 g deionized water, and 1 g of 1N hydrochloric acid are mixed and then the mixed solution is stirred at room temperature for 30 minutes to form a solution T 5 . 
     The solution T 5  is slowly added to the solution B 5 , which is still being stirred. After the mixed solution is stirred at room temperature for 60 minutes, the solution A 5  is slowly added to the mixed solution and together are stirred at room temperature for 90 minutes, then the temperature is increased to 50° C.: and the mixed solution is stirred for 120 minutes to form a titanium silicon composite solution D 5 . Then, the titanium silicon composite solution D 5  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     The second dielectric layer of example 5 may include the structure as indicated in the following Formula 2: 
     
       
         
         
             
             
         
       
     
     EXAMPLE 6 
     11.28 g of water-containing stannous chloride (SnCl 2 ·2H 2 O) are added to 46 g of ethanol , then the mixed solution is stirred at room temperature for 24 hours to form a solution A 6 . 
     2.76 g of 65-70% nitric acid and 7.6 g of ethanol are added to 10 g of deionized water, then the mixed solution is stirred for 20 minutes to form a catalytic solution T6. 8.5 g of titanium (IV)-butoxide and 27.6 g of ethanol are mixed and stirred for 20 minutes, then the mixed solution is slowly added to the catalytic solution T 6 , and together are stirred at room temperature for 60 minutes to form a solution B 6 . 
     5 g of the solution A 6  (that is, tin-containing solution) and 5 g of the solution B 6  (that is, titanium-containing solution) are mixed then the mixed solution is stirred at room temperature for 16 hours to obtain a titanium-tin composite solution D 6 . Then, the titanium-tin composite solution D 6  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     The second dielectric layer of example 6 may comprise the structure as indicated in the following Formula 3: 
     
       
         
         
             
             
         
       
     
     Comparison example 2 
     36 g of tetraethoxysilane (TEAS), 90 g of methyltriethoxysilane (MTES), 18 g of (3-glycidyloxypropyl) trimethoxysilane (GPTMS) and 36 g of 0.1N nitric acid solution are mixed and then are stirred and reacted at room temperature for 16 hours. Then, the mixed solution is reacted at 60° C. for 8 hours to form a solution A 12  The solution A 12  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     Comparison example 3 
     1 g of 3-(trimethoxysilyl)-propylmethacrylate (MSMA) is added to 20 g of n-butanol, then the mixed solution is stirred at room temperature for 30 minutes to form a solution A 13 . 
     27.8 g of titanium (IV)-butoxide are added to 40 g of n-butanol then the mixed solution is stirred at room temperature for 30 minutes to form a solution B13. 60 g of n-butanol, 1.12 g of deionized water, and 1 g of 1N hydrochloric acid are mixed, then the mixed solution is stirred at room temperature for 30 minutes to form a solution T 13 . 
     The solution T13 is slowly added to the solution B 13 , which is still being stirred. After the mixed solution is stirred at room temperature for 60 minutes, the solution A 13  is slowly added to the mixed solution and together are stirred at room temperature for 90 minutes, then the temperature is increased to 50° C. and the mixed solution is stirred for 120 minutes to form a titanium silicon composite solution D 13 . Then, the titanium silicon composite solution D 13  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     Comparison Example 4 
     8.5 g of titanium (IV)-butoxide are added to 27.6 g of ethanol, then the mixed solution is stirred for 20 minutes to form a solution B 14 . Then, 2.76 g of 65-70% nitric acid and 7.6g of ethanol are added to 10 g of deionized water and together are stirred for 20 minutes to form a catalytic solution T 14 . 
     The catalytic solution T 14  is slowly added to the solution B 14  and together are stirred at room temperature for 60 minutes to form a solution D 14 . Then, the solution D 14  is coated on the first dielectric layer by a brushing method and is cured at 140° C. for 20 minutes and then is further baked at 200° C. for 16 hours to form a second dielectric layer. 
     The materials, the features and the film formation state of the second dielectric layer of each of examples 1-6 and comparison examples 2-4 are illustrated in the following Table 1. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                   
                 Material and property of the second dielectric layer 
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                 Precursor of 
                   
                   
                 Film formation state of the 
                   
               
               
                   
                 Precursor of 
                 the group IVA 
                   
                 Mole ratio of 
                 second dielectric layer 
                 Film formation state of the 
               
               
                   
                 titanium/ 
                 elements/ 
                 Stability 
                 titanium 
                 following the curing step 
                 second dielectric layer 
               
               
                   
                 amount 
                 amount 
                 *1 
                 *2 
                 *3 
                 following the baking step *4 
               
               
                   
               
               
                 Example 1 
                 TBO/0.75 g 
                 TEOS: 4.0 g 
                 No gelation 
                  7.95% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                 MTES: 10.0 g 
                 for 7 days 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                 GPTMS: 2.0 g 
                   
                   
                   
                   
               
               
                 Example 2 
                 TBO/2.26 g 
                 TEOS: 7.0 g 
                 No 
                 12.89% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                 MTES: 17.5 g 
                 gelation 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                 GPTMS: 3.5 g 
                 for 7 days 
                   
                   
                   
               
               
                 Example 3 
                 TBO/3.01 g 
                 TEOS: 6.0 g 
                 No 
                 18.72% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                 MTES: 15 g 
                 gelation 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                 GPTMS: 3 g 
                 for 7 days 
                   
                   
                   
               
               
                 Example 4 
                 TBO/3.01 g 
                 TEOS: 4.0 g 
                 No 
                 25.67% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                 MTES: 10.0 g 
                 gelation 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                 GPTMS: 2.0 g 
                 for 7 days 
                   
                   
                   
               
               
                 Example 5 
                 TBO/27.8 g 
                 MSMA: 2.0 g 
                 No 
                 91.03% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                   
                 gelation 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                   
                 for 30 days 
                   
                   
                   
               
               
                 Example 6 
                 TBO/4.9 g 
                 SnCl2•2H 2 O: 
                 No 
                 76.82%  
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                   
                   
                 1 g 
                 gelation 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                   
                 for 7 days 
                   
                   
                   
               
            
           
           
               
               
            
               
                 Comparison 
                 N/A 
               
               
                 example 1 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Comparison 
                 N/A 
                 TEOS: 4.0 g 
                 No gelation 
                    0% 
                 Structure is intact complete 
                 Structure is intact complete 
               
               
                 example 2 
                   
                 MTES: 10.0 g 
                 for 30 days 
                   
                 without deterioration 
                 without deterioration 
               
               
                   
                   
                 GPTMS: 2.0 g 
                   
                   
                   
                   
               
               
                 Comparison 
                 TBO/27.8 g 
                 MSMA: 1.0 g 
                 No 
                  95.3% 
                 Film layer cracks and peels off 
                 Film layer cracks and peels off 
               
               
                 example 3 
                   
                   
                 gelation 
                   
                   
                   
               
               
                   
                   
                   
                 for 30 days 
                   
                   
                   
               
               
                 Comparison 
                 TBO/8.5 g 
                 N/A 
                 Gelation 
                   100% 
                 Powders precipitate/ 
                 Powders precipitate/ 
               
               
                 example 4 
                   
                   
                 after 3 days 
                   
                 film cannot be formed 
                 film cannot be formed 
               
               
                   
               
               
                 *1: Solutions D1-D6, A12, D13 and D14 are placed at room temperature, and respective solution stability is observed. 
               
               
                 *2: If the mole number of titanium is M1 and the mole number of the group IVA elements is M2, then the mole ratio of titanium is expressed as: (mol/mol) = M1/(M1 + M2) 
               
               
                 *3: cured at 140° C. for 20 minutes 
               
               
                 *4: Baked at 200° C. for 16 hours 
               
            
           
         
       
     
     As illustrated in Table 1, since each of the solutions D 1 -D 6  for forming the second dielectric layer of examples 1˜6 of the present disclosure includes the group IVA elements which can stabilize the structure of the oxide of titanium, the second dielectric layer possesses excellent stability, and will not generate any changes (gelation) after having been placed at room temperature for 7 days, and the structure is still intact complete without deterioration after the curing and baking step is performed. Conversely, since the solution D 14  for forming the second dielectric layer of comparison example 4 does not include the group IVA elements which can stabilize the structure of the oxide of titanium, the second dielectric layer has poor stability, is gelatinized after 3 days, and precipitate powders and cannot form film after the curing and baking step is performed. Additionally, since the mole ratio of titanium of comparison example 3 is too large (larger than 95%), the film layer will crack and peel off after the curing and baking step is performed. 
       FIG. 4  is a schematic diagram of an assembly equipment for testing the electrostatic clamping force of an electrostaticchuck  10 A. 
     Refer to  FIG. 4 . An object  12  to be clamped (such as glass or wafer) is placed above the electrostatic chuck  10 A. The electrostatic chuck  10 A can be realized by the electrostatic chuck of any embodiment or any comparison example of the present disclosure. One end of the heat-resistant tape  14  is fixed on the electrostatic chuck  10 A, and the other end of the heat-resistant tape  14  is connected to a tension meter  16  (such as the tension meter manufactured by the Calitech Co., Ltd.).After a positive voltage +V (such as +1200V) and a negative voltage −V (such as  31  1200V) are respectively applied to the electrostatic chuck  10 A, the electrostatic damping force generated by the electrostatic chuck  10 A is measured by using the tension meter  16 . 
     The electrostatic clamping force of the assembly equipment of  FIG. 4  is measured according to the conditions of examples 2 and 5 and comparison examples 1, 2 and 4 , and the results are listed in Table 2. 
     
       
         
           
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                   
                 Electrostatic clamping force test (gf/cm 2 ) 
               
            
           
           
               
               
               
               
               
            
               
                   
                 25° C. initial 
                 60° C. 
                 12 h vacuum 
                 76 h vacuum 
               
               
                   
                 electrostatic 
                 electrostatic 
                 (&lt;10torr) 
                 (&lt;10torr) 
               
               
                   
                 clamping 
                 clamping  
                 electrostatic 
                 electrostatic 
               
               
                   
                 force 
                 force 
                 clamping force 
                 clamping force 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 example 2 
                 11.6 
                 4.8 
                 7.0 
                 3.8 
               
               
                 example5 
                 13.3 
                 7.3 
                 10.9 
                 6.3 
               
               
                 Comparison 
                 8.0 
                 1.8 
                 2.0 
                 — 
               
               
                 example 1 
                   
                   
                   
                   
               
               
                 Comparison 
                 4.3 
                 1.3 
                 — 
                 — 
               
               
                 example 2 
                   
                   
                   
                   
               
               
                 Comparison 
                 Film cannot  
                 Film cannot  
                 Film cannot  
                 Film cannot  
               
               
                 example 4 
                 be formed/ 
                 be formed/ 
                 be formed/ 
                 be formed/ 
               
               
                   
                 Cannot be 
                 Cannot be 
                 Cannot be  
                 Cannot be  
               
               
                   
                 tested 
                 tested 
                 tested 
                 tested 
               
               
                   
               
            
           
         
       
     
     As illustrated in Table 2, the electrostatic chuck of each of the examples 2 and 5 of the present disclosure includes a second dielectric layer having a densed structure capable of sealing the gaps of the first dielectric layer, and the second dielectric layer further includes titanium having a high dielectric constant. Unlike the comparison example 1, in which the electrostatic chuck only includes a first dielectric layer and the electrostatic damping force greatly deteriorates due to the evaporation of water moisture, in the examples 2 and 5 of the present disclosure the electrostatic chuck has a large electrostatic damping force under the condition of 25° C. and 60° C., and still can reach the electrostatic clamping force of 3.8 gf/cm 2  and 6.3 gf/cm 2  even in a vacuum environment for a long duration (76 hours). Besides, the second dielectric layer of examples 2 and 5 of the present disclosure includes titanium having a high dielectric constant, and therefore provides a larger electrostatic clamping force than the second dielectric layer of comparison example 2 which does not include titanium. 
     According to an embodiment of the present disclosure, an electrostatic chuck and a method for manufacturing the same are provided. The electrostatic chuck comprises a base and an insulating layer, an electrode layer, a first dielectric layer and a second dielectric layer sequentially stacked on the base. The first dielectric layer comprises aluminum oxide (Al 2 O 3 ) or aluminum nitride (AlN), The material of the second dielectric layer is different from the material of the first dielectric layer, and the second dielectric layer includes titanium, a group IVA element and oxygen. Unlike the comparison example in which the electrostatic chuck includes only the first dielectric layer formed of aluminum oxide or the second dielectric layer of the electrostatic chuck which does not include titanium, in the present disclosure, the second dielectric layer of the electrostatic chuck includes titanium, such that the electrostatic chuck has a larger overall dielectric constant and can provide a larger electrostatic clamping force. Moreover, in comparison to the electrostatic chuck of the comparison example which does not include a second dielectric layer, the electrostatic chuck of the present disclosure includes a second dielectric layer, which seals the gaps of the first dielectric layer and avoids the water moisture being evaporated due to the high temperature and long duration of vacuum state in the semiconductor process and reducing the absorption ability of the electrostatic chuck. Therefore, the electrostatic chuck of the present disclosure can increase the electrostatic clamping force, the lifespan can be extended and the fluency of the semiconductor process can be increased. 
     While the disclosure has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.