Silicon carbide and other films and method of deposition

Abstract

A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

1. A process for achieving a predetermined value in a desired property selected from residual stress and electrical resistivity in a product ceramic film deposited on a substrate by low pressure chemical vapor deposition, the ceramic being formed from a metallic element and a non-metallic element, the product ceramic film being formed by
 supplying a metallic element precursor to a reaction chamber,   separately supplying a non-metallic element precursor different from the metallic element precursor to the reaction chamber under conditions of temperature and pressure such that the metallic element precursor and the non-metallic element precursor react to form the product ceramic film on a substrate inside the reaction chamber,   the process comprising
 (a) selecting pressure or flow rate of the metallic element precursor as the control variable, 
 (b) determining the relationship between the desired property and the control variable when the remaining variables in the low temperature vapor deposition process are held at selected fixed values, and 
 (c) during formation of the product ceramic film, achieving the predetermined value for the desired property by controlling the control variable while maintaining the remaining variables at the above selected fixed values. 
   
     
     
       2. A process according to  claim 1  for achieving a desired residual stress or electrical resistivity in a product silicon carbide film deposited on a substrate by low pressure chemical vapor deposition, the product silicon carbide film being formed by
 supplying a silicon precursor to a reaction chamber, 
 a separately supplying a carbon precursor different from the silicon precursor to the reaction chamber under conditions of temperature and pressure such that the silicon precursor and the carbon precursor react to form the product silicon carbide film on a substrate inside the reaction chamber, 
 the process comprising
 (a) selecting pressure or flow rote of the silicon precursor as the control variable, 
 (b) determining the relationship between residual stress or electrical resistivity and the control variable when the remaining variables in the low temperature vapor deposition process are held at selected fixed values, and 
 (c) during formation of the product silicon carbide film, achieving the desired residual stress or electrical resistivity by controlling the control variable while maintaining the remaining variables at the above selected fixed values. 
 
 
     
     
       3. The method of  claim 2 , wherein the silicon precursor is selected from the group consisting of silane, halosilane, trimethylsilane, tetramethylsilane, dimethyldimethoxysilane, tetramethylcyclotetrasiloxane, bis-trimethylsilylmethane, methyltrichlorosilane, silane, tetraethylsilane, and silacyclobutane. 
     
     
       4. The method of  claim 3 , wherein the halosilane is selected from the group consisting of dichlorosilane, trichlorosilane, and tetrachlorosilane. 
     
     
       5. The method of  claim 4 , wherein the silicon precursor is dichlorosilane. 
     
     
       6. The method of  claim 2 , wherein the flow rate of the carbon precursor is about 180 standard cubic centimeters per minute. 
     
     
       7. The method of  claim 2 , wherein supplying carbon precursor comprises supplying acetylene in hydrogen to the reaction chamber at a flow rate of about 180 standard cubic centimeters per minute. 
     
     
       8. The process or  claim 2 , wherein the product silicon carbide film is produced to have a predetermined electrical resistivity of about 10 Ω·cm or less. 
     
     
       9. The process of  claim 8 , wherein the predetermined electrical resistivity is achieved by controlling silicon precursor flow rate. 
     
     
       10. The process of  claim 9 , wherein the silicon precursor flow rate is set to a value between about 30 and 54 sccm to achieve the predetermined electrical resistivity. 
     
     
       11. The process of  claim 8 , wherein the predetermined electrical resistivity is achieved by controlling pressure. 
     
     
       12. The process of  claim 11 , wherein pressure is set to a value between about 0.42 torr and about 5 torr to achieve the predetermined electrical resistivity. 
     
     
       13. The process of  claim 2 , wherein the product silicon carbide film is produced to have a predetermined residual stress between about 700 MPa to about and −100 MPa. 
     
     
       14. The process of  claim 13 , wherein the predetermined residual stress is achieved by controlling pressure. 
     
     
       15. The process of  claim 14 , wherein the pressure in the reaction chamber is set to a value between about 0.42 torr and about 5 torr to achieve the predetermined residual stress. 
     
     
       16. The process of  claim 15 , wherein the pressure in the reaction chamber is set to a value of about 2 torr. 
     
     
       17. The process of  claim 13 , wherein the predetermined residual stress is achieved by controlling silicon precursor flow rate. 
     
     
       18. The process of  claim 17 , wherein the silicon precursor flow rate is set to a value between about 18 and 54 sccm to achieve the predetermined residual stress. 
     
     
       19. A method of depositing a silicon carbide film on a substrate by chemical vapor deposition, comprising
 (a) placing at least one substrate in a reaction chamber;   (b) maintaining the reaction chamber at a predetermined pressure;   (c) supplying carbon precursor to the reaction chamber at a predetermined fixed flow rate;   (d) supplying silicon precursor to the reaction chamber at a flow rate; and   (e) controlling the silicon precursor flow rate to control the stress in the deposited silicon carbide film.   
     
     
       20. A method for forming a silicon carbide layer on a substrate, the method comprising:
 providing a first gas to a reaction chamber that contains the substrate, wherein the first gas comprises silicon, and wherein the first gas is provided at a first flow rate;   providing a second gas to the reaction chamber, wherein the second gas comprises carbon, and wherein the second gas is provided at a second flow rate;   selecting a control variable as one of the first flow rate and a pressure in the reaction chamber;   forming the silicon carbide layer on the substrate; and   controlling the control variable to control at least two properties of the silicon carbide layer, wherein the control variable is controlled based on an established relationship between the control variable and each of the two properties;   wherein one controlled property is electrical resistivity and one controlled property is one of residual stress and residual stress gradient.   
     
     
       21. The method of claim 20 wherein the silicon carbide layer is formed by a low-pressure chemical vapor deposition. 
     
     
       22. The method of claim 20 further comprising determining the established relationship between the control variable and each of the two properties by characterizing each of the two properties for a silicon carbide test layer grown in the reaction chamber at each of a plurality of deposition conditions, and wherein each of the plurality of deposition conditions includes a different value for the selected control variable. 
     
     
       23. The method of claim 20 wherein residual stress is selected as one of the two properties, and wherein the control variable is controlled such that the silicon carbide layer is characterized by residual stress that is within the range of approximately −100 MPa to approximately +100 MPa. 
     
     
       24. The method of claim 20 wherein the control variable is controlled such that the silicon carbide layer is characterized by electrical resistivity that is less than approximately 10 Ω-cm. 
     
     
       25. The method of claim 20 wherein the control variable is selected as the pressure. 
     
     
       26. The method of claim 20 wherein the control variable is selected as the first flow rate. 
     
     
       27. The method of claim 20, further comprising selecting the first gas from the group consisting of silane, dichlhorosilane, trichlorosilane, tetrachlorosilane, halosilane, trimethylsilane, tetramethylsilane, dimethyldimethoxysilane, tetramethylcyclotetrasiloxane, bis-trimethylsilylmethane, methyltrichlorosilane, silane, tetraethylsilane, and silacyclobutane. 
     
     
       28. The method of claim 20, further comprising selecting the first gas as dichlorosilane and the second gas as acetylene. 
     
     
       29. The method of claim 20 wherein the two properties are selected as residual stress and electrical resistivity. 
     
     
       30. The method of claim 29 wherein the control variable is controlled such that the silicon carbide layer is characterized by (1) residual stress that is within the range of approximately −100 MPa to approximately 100 MPa and (2) electrical resistivity that is less than approximately 10 Ω-cm. 
     
     
       31. The method of claim 20 wherein the two properties are selected as electrical resistivity and residual stress gradient. 
     
     
       32. The method of claim 31 wherein the silicon carbide layer is formed while controlling the control variable to further control the residual stress of the silicon carbide layer. 
     
     
       33. The method of claim 32 wherein the control variable is controlled such that the silicon carbide layer is characterized by (1) residual stress that is within the range of approximately −100 MPa to approximately 100 MPa and (2) electrical resistivity that is less than approximately 10 Ω-cm.