Methods for selective deposition to improve selectivity

Abstract

Methods and associated apparatus of forming a microelectronic structure are described. Those methods comprise providing a substrate comprising a region of higher active area density comprising source and drain recesses and a region of lower active area density comprising source and drain recesses, wherein the region of lower active area density further comprises dummy recesses, and selectively depositing a silicon alloy layer in the source, drain and dummy recesses to enhance the selectivity and uniformity of the silicon alloy deposition.

1 . A method of forming a microelectronic structure comprising; 
 providing a substrate comprising a region of higher active area density comprising source and drain recesses and a region of lower active area density comprising source and drain recesses, wherein the region of lower active area density further comprises dummy recesses; and    selectively depositing a silicon alloy layer in the source, drain and dummy recesses.    
   
   
       2 . The method of  claim 1  wherein selectively depositing a silicon alloy layer comprises selectively depositing a silicon alloy layer comprising silicon and germanium.  
   
   
       3 . The method of  claim 2  wherein selectively depositing a silicon alloy layer comprising silicon and germanium comprises selectively depositing a silicon germanium alloy layer comprising a p type dopant.  
   
   
       4 . The method of  claim 1  further comprising wherein the dummy recesses add an amount of exposed silicon to the region of lower active area density so that the exposed silicon density in the region of lower active area density substantially matches the exposed silicon density in the region of higher active area density.