Method of fabricating a MOS device

Abstract

Deposited dielectric layers for a semiconductor device are typically formed in a chemical vapor deposition. Often a hydrogen by-product is formed. Especially in a plasma enhanced chemical vapor deposition process, the hydrogen by-product can form free radicals that are introduced into the dielectric layers. The hydrogen free radicals can affect the stability of the threshold and breakdown voltage of MOSFET transistors. Deuterium introduced into the CVD chamber competes to enter the dielectric layer with the hydrogen. The deuterium prevents some of the hydrogen free radicals from entering the dielectric layer and thus increases MOSFET reliability.

What is claimed is:  
     
         1 . A method comprising: 
 providing a semiconductor wafer; and    forming a dielectric layer on the semiconductor wafer in a chemical vapor deposition process, the chemical vapor deposition process including introducing at least one reactant substance that includes hydrogen, the chemical vapor deposition process including the step of introducing deuterium during at least a portion of the chemical wafer deposition process so that at least some deuterium enters into the dielectric layer.    
     
     
         2 . The method of  claim 1 , wherein the dielectric layer forming step comprises introducing silane as the at least one reactant substance including hydrogen.  
     
     
         3 . The method of  claim 1 , wherein the dielectric layer forming step comprises introducing ammonia as the at least one reactant substance including hydrogen.  
     
     
         4 . The method of  claim 1 , wherein the dielectric layer forming step comprises introducing tetra-ethyl-ortho-silicate (TEOS) as the at least one reactant substance including hydrogen.  
     
     
         5 . The method of  claim 1 , wherein the dielectric layer forming step comprises introducing deuterium as a gas.  
     
     
         6 . The method of  claim 1 , wherein the dielectric layer forming step is done in a plasma enhanced chemical vapor deposition process.  
     
     
         7 . The method of  claim 1 , wherein the dielectric layer forming step is done after forming a metal layer on the semiconductor substrate, the dielectric layer forming step being done at a temperature to minimize the melting of the metal layer.  
     
     
         8 . The method of  claim 1 , wherein the dielectric layer forming step is such that hydrogen is formed as a by-product of the reaction of the reactant substances.  
     
     
         9 . The method of  claim 8 , wherein at least some of the by-product hydrogen is in the form of a free radical of hydrogen.  
     
     
         10 . The method of  claim 1 , wherein the dielectric layer forming step is such that the dielectric layer comprises an oxide.  
     
     
         11 . The method of  claim 1 , wherein the dielectric layer forming step is such that the dielectric layer comprises a nitride.  
     
     
         12 . The method of  claim 1 , wherein the dielectric layer forming step is such that the dielectric layer comprises an oxynitride.  
     
     
         13 . The method of  claim 1 , wherein the dielectric layer forming step is such that the dielectric layer is formed on a metal layer.  
     
     
         14 . The method of  claim 1 , wherein the dielectric layer forming step includes introducing deuterium at the beginning of the process.  
     
     
         15 . The method of  claim 1 , wherein the dielectric layer forming step includes introducing deuterium at the end of the process.  
     
     
         16 . A chemical vapor deposition system adapted for forming a dielectric layer on a substrate, the system comprising: 
 a chamber;    a supply of reactant substances, the supply adapted to introduce the reactant substances into the chamber, the reactant substances being such that they form a dielectric layer, wherein at least one of the reactant substances includes hydrogen; and    a supply of deuterium gas adapted to introduce the deuterium gas into the chamber during at least a portion of forming of the dielectric layer.    
     
     
         17 . The chemical vapor deposition system of  claim 16 , wherein the reactant substance supply includes silane as the at least one reactant substance including hydrogen.  
     
     
         18 . The chemical vapor deposition system of  claim 16 , further comprising at least one alternating current power supply so that the forming of the dielectric layer is a plasma enhanced chemical vapor deposition process.  
     
     
         19 . The chemical vapor deposition system of  claim 16 , wherein hydrogen is formed as a by-product of the reaction of the reactant substances.  
     
     
         20 . A semiconductor device comprising: 
 a substrate; and    layers, the layers including at least one dielectric layer on the semiconductor wafer, the at least one dielectric layer including at least some deuterium.    
     
     
         21 . The semiconductor device of  claim 20 , wherein the at least one dielectric layer includes at least 1% by weight deuterium.  
     
     
         22 . The semiconductor device of  claim 20 , wherein the at least one dielectric layer is such that the weight of deuterium is at least 20% of the weight of all hydrogen included in the dielectric layer.  
     
     
         23 . The semiconductor device of  claim 20 , wherein the at least one dielectric layer is a passivation layer.  
     
     
         24 . The semiconductor device of  claim 20 , wherein the at least one dielectric layer is an interlevel dielectric.  
     
     
         25 . The semiconductor device of  claim 20 , wherein the at least one dielectric layer is an inter-metallic layer.  
     
     
         26 . The semiconductor device of  claim 20 , further comprising additional dielectric layers that do not contain deuterium.