Film formation apparatus for semiconductor process and method for using the same

Abstract

A method is provided for using a film formation apparatus including a process container having an inner surface, which contains as a main component a material selected from the group consisting of quartz and silicon carbide. The method includes performing a film formation process to form a silicon nitride film on a product target substrate inside the process container, and then, unloading the product target substrate from the process container. Thereafter, the method includes supplying an oxidizing gas into the process container with no product target substrate accommodated therein, thereby performing an oxidation process to change by-product films deposited on the inner surface of the process container into a composition richer in oxygen than nitrogen, at a part of the by-product films from a surface thereof to a predetermined depth.

1 . A method for using a film formation apparatus including a process container having an inner surface, which contains as a main component a material selected from the group consisting of quartz and silicon carbide, the method comprising:
 performing a film formation process to form a silicon nitride film on a product target substrate inside the process container;   then, unloading the product target substrate from the process container; and   then, supplying an oxidizing gas into the process container with no product target substrate accommodated therein, thereby performing an oxidation process to change by-product films deposited on the inner surface of the process container into a composition richer in oxygen than nitrogen, at a part of the by-product films from a surface thereof to a predetermined depth.   
   
   
       2 . The method according to  claim 1 , wherein the oxidation process comprises a period of supplying the oxidizing gas into the process container while exciting the oxidizing gas by a plasma exciting mechanism, thereby oxidizing the by-product films by use of radicals of the oxidizing gas thus generated. 
   
   
       3 . The method according to  claim 2 , wherein the oxidizing gas comprises oxygen. 
   
   
       4 . The method according to  claim 2 , wherein the oxidation process is arranged to set the process container to have an inner pressure of 30 to 300 Pa. 
   
   
       5 . The method according to  claim 2 , wherein the oxidation process is arranged to set the inner surface of the process container at a temperature of 400 to 6500. 
   
   
       6 . The method according to  claim 1 , wherein the predetermined depth is set to be of 1 to 10 nm. 
   
   
       7 . The method according to  claim 1 , wherein the oxidation process is arranged to supply the oxidizing gas into the process container without exciting the oxidizing gas by a plasma exciting mechanism. 
   
   
       8 . The method according to  claim 7 , wherein the oxidation process is arranged to set the inner surface of the process container at a temperature of 400 to 800□. 
   
   
       9 . The method according to  claim 1 , wherein, after the oxidation process, the method further comprises supplying a nitriding gas into the process container with no product target substrate accommodated therein, thereby performing a nitridation process to return a surface layer of the oxidized by-product films into a composition richer in nitrogen than oxygen. 
   
   
       10 . The method according to  claim 9 , wherein the surface layer has a thickness of 0.1 to 0.5 nm. 
   
   
       11 . The method according to  claim 9 , wherein the nitridation process comprises a period of supplying the nitriding gas into the process container while exciting the nitriding gas by a plasma exciting mechanism, thereby nitriding the surface layer of the by-product films by use of radicals of the nitriding gas thus generated. 
   
   
       12 . The method according to  claim 9 , wherein the nitriding gas comprises ammonia. 
   
   
       13 . The method according to  claim 11 , wherein the nitridation process is arranged to set the process container to have an inner pressure of 50 to 100 Pa. 
   
   
       14 . The method according to  claim 11 , wherein the nitridation process is arranged to set the inner surface of the process container at a temperature of 400 to 650□. 
   
   
       15 . The method according to  claim 1 , wherein the film formation process comprises supplying a first film formation gas comprising a silicon source gas and a second film formation gas comprising a nitriding gas into the process container, thereby forming a silicon nitride film by CVD. 
   
   
       16 . The method according to  claim 15 , wherein the oxidation process is performed before a cumulative film thickness of silicon nitride films obtained by repeating the film formation process a plurality of times exceeds a predetermined value. 
   
   
       17 . The method according to  claim 15 , wherein, after the oxidation process, the method further comprises supplying a nitriding gas, which is the same as the nitriding gas used for the second film formation gas, into the process container with no product target substrate accommodated therein, thereby performing a nitridation process to return a surface layer of the oxidized by-product films into a composition richer in nitrogen than oxygen. 
   
   
       18 . The method according to  claim 1 , wherein the process container is configured to accommodate a plurality of target substrates at intervals in a vertical direction, and the target substrates are heated by a heater disposed around the process container. 
   
   
       19 . A film formation apparatus for a semiconductor process, comprising:
 a process container configured to accommodate a target substrate and having an inner surface, which contains as a main component a material selected from the group consisting of quartz and silicon carbide,   a heater configured to heat the target substrate inside the process container;   an exhaust system configured to exhaust gas from inside the process container;   a film formation gas supply circuit configured to supply a film formation gas for forming a silicon nitride film into the process container;   an oxidizing gas supply circuit configured to supply an oxidizing gas for performing an oxidation process on by-product films into the process container;   a mechanism configured to load and unload the target substrate to and from the process container;   a control section configured to control an operation of the apparatus,   wherein the control section is preset to execute a method that comprises   performing a film formation process to form a silicon nitride film on a product target substrate inside the process container;   then, unloading the product target substrate from the process container; and   then, supplying an oxidizing gas into the process container with no product target substrate accommodated therein, thereby performing an oxidation process to change by-product films deposited on the inner surface of the process container into a composition richer in oxygen than nitrogen, at a part of the by-product films from a surface thereof to a predetermined depth.   
   
   
       20 . A computer readable medium containing program instructions for execution on a processor, which is used for a film formation apparatus including a process container having an inner surface, which contains as a main component a material selected from the group consisting of quartz and silicon carbide, wherein the program instructions, when executed by the processor, control the film formation apparatus to execute a method that comprises
 performing a film formation process to form a silicon nitride film on a product target substrate inside the process container;   then, unloading the product target substrate from the process container; and   then, supplying an oxidizing gas into the process container with no product target substrate accommodated therein, thereby performing an oxidation process to change by-product films deposited on the inner surface of the process container into a composition richer in oxygen than nitrogen, at a part of the by-product films from a surface thereof to a predetermined depth.