Method of preventing autodoping

Abstract

A method of making a silicon-based electronic device is provided. The method includes, for example, the steps of forming a doped silicon layer on a surface of a substrate material and forming an undoped silicon capping layer on the doped silicon layer. The thin “capping” layers of undoped silicon prevent outgassing of the dopants underneath the cap. In this manner, the next deposition of doped silicon is not subject to autodoping by the previous doped silicon deposition.

What is claimed is:  
     
         1 . A method of making a semiconductor device comprising: 
 forming a first in-situ doped silicon layer over a substrate material in a pressure vessel while introducing a precursor gas;    without removing the substrate material from the pressure vessel, discontinuing introduction of the precursor gas and forming an undoped silicon capping layer on and in contact with the doped silicon layer; and    removing the undoped silicon capping layer.    
     
     
         2 . The method of  claim 1  wherein the undoped silicon capping layer is removed by CMP.  
     
     
         3 . The method of  claim 1  further comprising, after the step of removing the undoped silicon capping layer, depositing a second in-situ doped silicon layer.  
     
     
         4 . The method of  claim 3  wherein the first doped layer is formed with an n-type dopant or a p-type dopant, and the second doped layer is formed with a p-type dopant or an n-type dopant, the type of the second layer opposite the type of the first doped layer.  
     
     
         5 . The method of  claim 3  wherein the doped layers form a portion of a memory device.  
     
     
         6 . The method of  claim 5  wherein the memory device forms a portion of a three dimensional memory array.  
     
     
         7 . A method of conditioning a pressure vessel to prevent autodoping, the method comprising the steps of: 
 forming a first doped silicon layer in the pressure vessel over a surface of a first wafer while introducing a precursor gas;    without removing the first wafer from the pressure vessel, discontinuing introduction of the precursor gas and forming an undoped silicon capping layer on and in contact with the first doped silicon layer and on exposed surfaces in the pressure vessel; and    introducing a second wafer into the pressure vessel after formation of the undoped capping layer and forming a second silicon layer over a surface of the second wafer, wherein the thickness of the undoped capping layer is sufficient to reduce autodoping in the second silicon layer to approximately a background level.    
     
     
         8 . The method of  claim 7  wherein the undoped silicon capping layer, when formation is complete, is thinner than the first doped layer.  
     
     
         9 . The method of  claim 8  wherein the thickness of the undoped silicon capping layer is about 500 angstroms or less.  
     
     
         10 . The method of  claim 8  wherein the thickness of the undoped silicon capping layer is between about 500 angstroms or and about 200 angstroms.  
     
     
         11 . The method of  claim 7  wherein the second silicon layer is undoped.  
     
     
         12 . The method of  claim 7  wherein the first doped layer is formed with an n-type dopant or a p-type dopant, and the second layer is formed with a p-type dopant or an n-type dopant, the type of the second layer opposite the type of the first doped layer.  
     
     
         13 . The method of  claim 7  wherein the first or the second silicon layer forms a portion of a memory device.  
     
     
         14 . The method of  claim 13  wherein the memory device forms a portion of a three dimensional memory array.  
     
     
         15 . A method of making a silicon-based electronic device comprising the steps of: 
 forming a first doped silicon layer in a pressure vessel over a surface of a product wafer substrate material while introducing a precursor gas;    without removing the substrate material from the pressure vessel, discontinuing introduction of the precursor gas and forming an undoped silicon capping layer on and in contact with the first doped silicon layer; and    forming a second doped silicon layer on and in contact with the undoped silicon capping layer, wherein the layers form a portion of a memory device.    
     
     
         16 . The method of  claim 15  wherein the memory device is a portion of a three dimensional memory array.  
     
     
         17 . The method of  claim 16  wherein the undoped capping layer when formed is thinner than the first doped layer.  
     
     
         18 . The method of  claim 17  wherein the thickness of the undoped capping layer is between about 500 and about 200 angstroms.  
     
     
         19 . The method of  claim 15  wherein the first doped layer is formed with an n-type dopant or a p-type dopant, and the second doped layer is formed with a p-type dopant or an n-type dopant, the type of the second doped layer opposite the type of the first doped layer.  
     
     
         20 . A method of making a silicon-based electronic device comprising the steps of: 
 forming a first doped silicon layer in a pressure vessel over a surface of a product wafer substrate material while introducing a precursor gas; and    without removing the substrate material from the pressure vessel, discontinuing introduction of the precursor gas and forming an undoped silicon capping layer on and in contact with the first doped silicon layer,    wherein the layers form a portion of a three dimensional memory array.    
     
     
         21 . The method of  claim 20  wherein the undoped capping layer is thinner than the first doped layer.  
     
     
         22 . The method of  claim 21  wherein the thickness of the undoped capping layer is between about 500 and about 200 angstroms.  
     
     
         23 . The method of  claim 20  further comprising forming a second doped layer on and in contact with the undoped capping layer.  
     
     
         24 . The method of  claim 23  wherein the first doped layer is formed with n-type or p-type dopants and the second layer is formed with n-type or p-type dopants, the type of the second layer opposite the type of the first layer.  
     
     
         25 . A method of making a semiconductor device comprising: 
 forming a first in-situ doped silicon layer over a substrate material in a pressure vessel while introducing a precursor gas;    without removing the substrate material from the pressure vessel, discontinuing introduction of the precursor gas and forming an undoped silicon capping layer on the doped silicon layer; and    consuming or removing the undoped silicon capping layer, wherein the semiconductor device is a memory device.    
     
     
         26 . The method of  claim 25 , wherein the undoped silicon capping layer is removed by CMP.  
     
     
         27 . The method of  claim 25 , wherein the undoped silicon capping layer is reactively consumed.  
     
     
         28 . The method of  claim 25 , further comprising, after the step of consuming or removing the undoped silicon capping layer, depositing a second in-situ doped silicon layer.  
     
     
         29 . The method of  claim 25 , wherein the memory device is a portion of a three dimensional memory array.  
     
     
         30 . The method of  claim 25  wherein the undoped capping layer, when formed, is thinner than the first doped layer.  
     
     
         31 . The method of  claim 30  wherein the thickness of the undoped capping layer is between about 500 and about 200 angstroms.