Etching method and cleaning method of chemical vapor growth apparatus

Abstract

Presented is an etching method capable of easily etching an oxide containing an alkaline-earth metal. One method is to etch the oxide by using an etching gas containing a halogen gas except for fluorine, an interhalogen compound consisting of only a halogen element except for fluorine, or a halogen hydride consisting of a halogen element except for fluorine and hydrogen. Particularly chlorides, bromides, and iodides of alkaline-earth metals have relatively high vapor pressures, so a thin film containing an alkaline-earth metal can be etched by using chlorine gas, bromine gas, or iodine gas. When a halogen gas containing fluorine is used, damages to SiO 2 portions used in a film formation apparatus are prevented by coating these SiO 2 portions with a fluoride of an alkaline-earth metal.

1 . An etching method comprising the steps of: 
 preparing an oxide layer containing at least one type of alkaline-earth metal; and    etching the oxide layer containing at least one type of alkaline-earth metal by using, as an etching gas, either a halogen gas other than fluorine gas, or a gas containing at least one material selected from the group consisting of an interhalogen compound consisting of halogen elements other than fluorine, and a halogen hydride consisting of a halogen element other than fluorine and hydrogen.    
     
     
         2 . The etching method according to  claim 1 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         3 . The etching method according to  claim 1 , wherein the step of etching the oxide layer includes a step of etching in an ambient at not less than 500° C.  
     
     
         4 . The etching method according to  claim 3 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         5 . The etching method according to  claim 1 , wherein the step of etching the oxide layer includes a step of etching the oxide layer while changing an etching temperature.  
     
     
         6 . The etching method according to  claim 5 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         7 . The etching method according to  claim 5 , wherein the step of etching the oxide layer includes: 
 a first etching step having a first etching condition; and    a second etching step having a second etching condition, and    the etching temperature in the first etching step is different from the etching temperature in the second etching step.    
     
     
         8 . The etching method according to  claim 7 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         9 . The etching method according to  claim 7 , wherein the second etching step is successively performed after the first etching step, and the etching temperature in the first etching step is lower than the etching temperature in the second etching step.  
     
     
         10 . The etching method according to  claim 9 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         11 . The etching method according to  claim 9 , further comprising a step of repeating a plurality of times the step of successively performing the first and the second step.  
     
     
         12 . The etching method according to  claim 11 , wherein the step of etching the oxide layer includes a step of etching using chlorine gas as the etching gas.  
     
     
         13 . The etching method according to  claim 1 , wherein the step of etching the oxide layer includes a step of using a gas activated by plasma excitation as the etching gas.  
     
     
         14 . The etching method according to  claim 1 , wherein the oxide layer is a (Ba,Sr)TiO 3  layer.  
     
     
         15 . An etching method comprising the steps of: 
 preparing an oxide layer containing at least one type of alkaline-earth metal; and    etching the oxide layer containing at least one type of alkaline-earth metal by using an etching gas composed of a gas containing a halogen element and a gas consisting of a halide of Ti.    
     
     
         16 . The etching method according to  claim 15 , wherein the step of etching the oxide layer includes a step of etching by using a gas containing at least fluorine as the gas containing a halogen element.  
     
     
         17 . A chemical vapor growth apparatus comprising: 
 a reaction chamber;    a heating mechanism for heating the reaction chamber;    a reaction gas supply unit connected to the reaction chamber to supply a reaction gas;    a reaction gas exhaust unit connected to the reaction chamber to exhaust the reaction gas from the reaction chamber; and    a member installed in the reaction chamber,    wherein one of the reaction chamber and the member has a portion made of quartz, and at least a part of a surface of the quartz portion, which is exposed to the reaction gas, is coated with a fluoride of an alkaline-earth metal.    
     
     
         18 . A cleaning method of a hot wall type chemical vapor growth apparatus which uses a quartz member and deposits an oxide containing at least one type of alkaline-earth metal, comprising the steps of; 
 depositing a fluoride of alkaline-earth metal at least on a surface of the quartz member;    depositing the oxide on a deposition substrate not less than once; and    etching the oxide by using an etching gas containing a fluorine compound.    
     
     
         19 . The cleaning method according to  claim 18 , wherein the step of etching the oxide includes a step of using an etching gas further containing a halide of Ti as the etching gas.