Deep trench etching using HDP chamber

Abstract

A process for etching deep trenches in a substrate for purposes such as the fabrication of microelectromechanical systems (MEMS), for example, on the substrate. The two-step process includes first etching a tapered trench having a tapered profile and enhanced sidewall passivation in a substrate along a protective mask which defines the desired trench profile on the substrate surface. Next, the tapered trench is trimmed by high-density plasma in an isotropic etching step to provide a straight-profile deep trench with minimum sidewall passivation.

1 . A process for forming a deep trench in a substrate, comprising the steps of: 
 providing an etch chamber;    placing said substrate in said etch chamber;    etching a tapered trench in said substrate by subjecting said substrate to a first etching step; and    etching said tapered trench to form said deep trench by subjecting said substrate to a second etching step.    
   
   
       2 . The process of  claim 1  wherein said first etching step includes providing a pressure of about 4˜20 mT in said etch chamber.  
   
   
       3 . The process of  claim 2  wherein said first etching step includes applying a bias power of about 10˜100 W and a source power of about 100˜800 W to said etch chamber.  
   
   
       4 . The process of  claim 3  wherein said first etching step includes flowing HBr and CF 4  into said etch chamber.  
   
   
       5 . The process of  claim 1  wherein said second etching step includes providing a pressure of about 5˜20 mT in said etch chamber.  
   
   
       6 . The process of  claim 5  wherein said second etching step includes applying a bias power of about 10˜200 W and a source power of about 500-1200 W to said etch chamber.  
   
   
       7 . The process of  claim 6  wherein said second etching step includes flowing HBr, O 2  and SF 6  into said etch chamber.  
   
   
       8 . A process for forming a deep trench in a substrate, comprising the steps of: 
 providing an etch chamber having a cathode and a chamber wall;    placing said substrate in said etch chamber;    maintaining said cathode at a temperature of about 10˜45 degrees C. and said chamber wall at a temperature of about 50˜100 degrees C.;    etching a tapered trench in said substrate by subjecting said substrate to a first etching step; and    etching said tapered trench to form said deep trench by subjecting said substrate to a second etching step.    
   
   
       9 . The process of  claim 8  wherein said first etching step includes providing a pressure of about 4˜20 mT in said etch chamber.  
   
   
       10 . The process of  claim 9  wherein said first etching step includes applying a bias power of about 10˜100 W and a source power of about 100˜800 W to said etch chamber.  
   
   
       11 . The process of  claim 10  wherein said first etching step includes flowing HBr and CF 4  into said etch chamber.  
   
   
       12 . The process of  claim 11  wherein said second etching step includes providing a pressure of about 5˜20 mT in said etch chamber.  
   
   
       13 . The process of  claim 12  wherein said second etching step includes applying a bias power of about 10˜200 W and a source power of about 500-1200 W to said etch chamber.  
   
   
       14 . The process of  claim 13  wherein said second etching step includes flowing HBr, O 2  and SF 6  into said etch chamber.  
   
   
       15 . A process for forming a deep trench in a substrate, comprising the steps of: 
 providing a high density plasma etch chamber having a cathode and a chamber wall;    placing said substrate in said etch chamber;    etching a tapered trench in said substrate by subjecting said substrate to a first etching step; and    etching said tapered trench to form said deep trench by subjecting said substrate to a second etching step.    
   
   
       16 . The process of  claim 15  wherein said first etching step and said second etching step includes maintaining said cathode at a temperature of about 10˜45 degrees C. and said chamber wall at a temperature of about 50˜100 degrees C.  
   
   
       17 . The process of  claim 15  wherein said first etching step includes providing a pressure of about 4˜20 mT in said etch chamber, applying a bias power of about 10˜100 W and a source power of about 100˜800 W to said etch chamber, and flowing HBr and CF 4  into said etch chamber.  
   
   
       18 . The process of  claim 17  wherein said first etching step and said second etching step includes maintaining said cathode at a temperature of about 10˜45 degrees C. and said chamber wall at a temperature of about 50˜100 degrees C.  
   
   
       19 . The process of  claim 17  wherein said second etching step includes providing a pressure of about 5˜20 mT in said etch chamber, applying a bias power of about 10˜200 W and a source power of about 500-1200 W to said etch chamber, and flowing HBr, O 2  and SF 6  into said etch chamber.  
   
   
       20 . The process of  claim 19  wherein said first etching step and said second etching step includes maintaining said cathode at a temperature of about 10˜45 degrees C. and said chamber wall at a temperature of about 50˜100 degrees C.