Film formation method and apparatus for semiconductor process

Abstract

A silicon nitride film is formed on a target substrate by performing a plurality of cycles in a process field configured to be selectively supplied with a first process gas containing a silane family gas and a second process gas containing a nitriding gas. Each of the cycles includes a first supply step of performing supply of the first process gas while maintaining a shut-off state of supply of the second process gas, and a second supply step of performing supply of the second process gas, while maintaining a shut-off state of supply of the first process gas. The method is arranged to repeat a first cycle set with the second supply step including an excitation period of exciting the second process gas and a second cycle set with the second supply step including no period of exciting the second process gas.

1 . A film formation method for a semiconductor process for forming a silicon nitride film on a target substrate, in a process field inside a process container configured to be selectively supplied with a first process gas containing a silane family gas and a second process gas containing a nitriding gas, and communicating with an exciting mechanism for exciting the second process gas to be supplied, the method comprising a film formation process arranged to perform a plurality of cycles in the process field with the target substrate placed therein to laminate thin films respectively formed by the cycles on the target substrate, thereby forming a silicon nitride film with a predetermined thickness, each of the cycles comprising:
 a first supply step of performing supply of the first process gas to the process field while maintaining a shut-off state of supply of the second process gas to the process field; and   a second supply step of performing supply of the second process gas to the process field while maintaining a shut-off state of supply of the first process gas to the process field,   wherein the method is arranged to repeat a first cycle set and a second cycle set mixedly a plurality of times without an essential change in a heating temperature set to the process field:   the first cycle set being composed of a cycle or cycles in which the second supply step comprises an excitation period of supplying the second process gas to the process field while exciting the second process gas by the exciting mechanism; and   the second cycle set being composed of a cycle or cycles in which the second supply step comprises no period of exciting the second process gas by the exciting mechanism.   
   
   
       2 . The method according to  claim 1 , wherein the method is arranged to repeat the first cycle set and the second cycle set alternately a plurality of times. 
   
   
       3 . The method according to  claim 1 , wherein the first cycle set is formed of a plurality of cycles. 
   
   
       4 . The method according to  claim 3 , wherein the number of cycles forming the first cycle set is larger than the number of cycles forming the second cycle set. 
   
   
       5 . The method according to  claim 1 , wherein each of the cycles further comprises first and second intermediate steps of exhausting gas from the process field while maintaining a shut-off state of supply of the first and second process gases to the process field, between the first and second supply steps and after the second supply step, respectively. 
   
   
       6 . The method according to  claim 5 , wherein each of the cycles is arranged to continuously exhaust gas from the process field through the first supply step, the first intermediate step, the second supply step, and the second intermediate step. 
   
   
       7 . The method according to  claim 5 , wherein each of the first and second intermediate steps comprises a period of supplying a purge gas to the process field. 
   
   
       8 . The method according to  claim 1 , wherein the second supply step of the first cycle set further comprises a period of supplying the second process gas to the process field while not exciting the second process gas by the exciting mechanism, before the excitation period. 
   
   
       9 . The method according to  claim 1 , wherein, before forming the silicon nitride film on the target substrate, the method further comprises a pre-coating process arranged to perform a plurality of pre-cycles in the process container with no target substrate placed therein to form a pre-coating film inside the process container, each of the pre-cycles comprising:
 a first pre-step of performing supply of the first process gas into the process container while maintaining a shut-off state of supply of the second process gas into the process container; and   a second pre-step of performing supply of the second process gas into the process container while maintaining a shut-off state of supply of the first process gas into the process container,   wherein the second pre-step comprises no period of exciting the second process gas by the exciting mechanism.   
   
   
       10 . The method according to  claim 9 , wherein the pre-coating process is executed while a support member for supporting the target substrate is set in an empty state or in a state with a dummy substrate supported thereon in place of the target substrate and is placed in the process field. 
   
   
       11 . The method according to  claim 9 , wherein each of the pre-cycles further comprises steps of exhausting gas from the process container while maintaining a shut-off state of supply of the first and second process gases into the process container, between the first and second pre-steps and after the second pre-step, respectively. 
   
   
       12 . The method according to  claim 1 , wherein the first and second supply steps are arranged to set the process field at a temperature of 300 to 700° C. 
   
   
       13 . The method according to  claim 1 , wherein the first and second supply steps are arranged to set the process field at a pressure of 13 Pa (0.1 Torr) to 13,300 Pa (100 Torr). 
   
   
       14 . The method according to  claim 1 , wherein the silane family gas contains at least one gas selected from the group consisting of dichlorosilane, hexachlorodisilane, monosilane, disilane, hexamethyldisilazane, tetrachlorosilane, disilylamine, trisilylamine, and bistertialbutylaminosilane, trimethylsilane, dimethylsilane, and monomethylamine, and the nitriding gas contains at least one gas selected from the group consisting of ammonia, nitrogen, dinitrogen oxide, and nitrogen oxide. 
   
   
       15 . The method according to  claim 14 , wherein each of the cycles of the film formation process further comprises a step or steps of supplying at least one gas selected from the group consisting of a doping gas and a carbon hydride gas. 
   
   
       16 . The method according to  claim 1 , wherein the process field is configured to accommodate a plurality of target substrates supported at intervals in a vertical direction on a support member. 
   
   
       17 . A film formation apparatus for a semiconductor process, comprising:
 a process container having a process field configured to accommodate a target substrate;   a support member configured to support the target substrate inside the process field;   a heater configured to heat the target substrate inside the process field;   an exhaust system configured to exhaust gas from the process field;   a first process gas supply circuit configured to supply a first process gas containing a silane family gas to the process field;   a second process gas supply circuit configured to supply a second process gas containing a nitriding gas to the process field;   an exciting mechanism configured to excite the second process gas to be supplied; and   a control section configured to control an operation of the apparatus,   wherein the control section is preset to execute a film formation method for a semiconductor process for forming a silicon nitride film on the target substrate, the method comprising a film formation process arranged to perform a plurality of cycles in the process field with the target substrate placed therein to laminate thin films respectively formed by the cycles on the target substrate, thereby forming a silicon nitride film with a predetermined thickness, each of the cycles comprising:   a first supply step of performing supply of the first process gas to the process field while maintaining a shut-off state of supply of the second process gas to the process field; and   a second supply step of performing supply of the second process gas to the process field while maintaining a shut-off state of supply of the first process gas to the process field,   wherein the method is arranged to repeat a first cycle set and a second cycle set mixedly a plurality of times without an essential change in a heating temperature set to the process field:   the first cycle set being composed of a cycle or cycles in which the second supply step comprises an excitation period of supplying the second process gas to the process field while exciting the second process gas by the exciting mechanism; and   the second cycle set being composed of a cycle or cycles in which the second supply step comprises no period of exciting the second process gas by the exciting mechanism.   
   
   
       18 . The apparatus according to  claim 17 , wherein, before forming the silicon nitride film on the target substrate, the film formation method executed by the control section further comprises a pre-coating process arranged to perform a plurality of pre-cycles in the process container with no target substrate placed therein to form a pre-coating film inside the process container, each of the pre-cycles comprising:
 a first pre-step of performing supply of the first process gas into the process container while maintaining a shut-off state of supply of the second process gas into the process container; and   a second pre-step of performing supply of the second process gas into the process container while maintaining a shut-off state of supply of the first process gas into the process container,   wherein the second pre-step comprises no period of exciting the second process gas by the exciting mechanism.   
   
   
       19 . A computer readable medium containing program instructions for execution on a processor, which is used for a film formation apparatus for a semiconductor process for forming a silicon nitride film on a target substrate, in a process field inside a process container configured to be selectively supplied with a first process gas containing a silane family gas and a second process gas containing a nitriding gas, and communicating with an exciting mechanism for exciting the second process gas to be supplied, wherein the program instructions, when executed by the processor, cause the film formation apparatus to conduct a film formation method comprising a film formation process arranged to perform a plurality of cycles in the process field with the target substrate placed therein to laminate thin films respectively formed by the cycles on the target substrate, thereby forming a silicon nitride film with a predetermined thickness, each of the cycles comprising:
 a first supply step of performing supply of the first process gas to the process field while maintaining a shut-off state of supply of the second process gas to the process field; and   a second supply step of performing supply of the second process gas to the process field while maintaining a shut-off state of supply of the first process gas to the process field,   wherein the method is arranged to repeat a first cycle set and a second cycle set mixedly a plurality of times without an essential change in a heating temperature set to the process field:   the first cycle set being composed of a cycle or cycles in which the second supply step comprises an excitation period of supplying the second process gas to the process field while exciting the second process gas by the exciting mechanism; and   the second cycle set being composed of a cycle or cycles in which the second supply step comprises no period of exciting the second process gas by the exciting mechanism.   
   
   
       20 . The medium according to  claim 19 , wherein, before forming the silicon nitride film on the target substrate, the film formation method executed in accordance with program instructions further comprises a pre-coating process arranged to perform a plurality of pre-cycles in the process container with no target substrate placed therein to form a pre-coating film inside the process container, each of the pre-cycles comprising:
 a first pre-step of performing supply of the first process gas into the process container while maintaining a shut-off state of supply of the second process gas into the process container; and   a second pre-step of performing supply of the second process gas into the process container while maintaining a shut-off state of supply of the first process gas into the process container,   wherein the second pre-step comprises no period of exciting the second process gas by the exciting mechanism.