Method for forming semiconductor devices with active silicon height variation

Abstract

A method for forming different active thicknesses on the same silicon layer includes masking the silicon layer and exposing selected regions of the silicon layer. The thickness of the silicon layer at the exposed regions is changed, either by adding silicon or subtracting silicon from the layer at the exposed regions. Once the mask is removed, the silicon layer has regions of different active thicknesses, respectively suitable for use in different types of devices, such as diodes and transistors.

What is claimed is: 
     
         1 . A semiconductor product, comprising:
 a semiconductor layer consisting essentially of silicon or silicon germanium with different active thicknesses on a single substrate;   the semiconductor layer having a first active region with a first thickness and a second active region with a second thickness less than the first thickness; and   the second active region being formed from a portion of the semiconductor layer from which silicon has been removed.   
     
     
         2 . The semiconductor product of  claim 1 , wherein the second active region is formed from the portion of the semiconductor layer by removing silicon by performing local oxidation of silicon. 
     
     
         3 . The semiconductor product of  claim 1 , wherein a diode is formed within the first active region. 
     
     
         4 . The semiconductor product of  claim 1 , wherein a transistor is formed within the second active region. 
     
     
         5 . The semiconductor product of  claim 1 , wherein a first type of device is formed within the first active region and a second type of device is formed within the second active region. 
     
     
         6 . The semiconductor product of  claim 5  wherein the first type of device is a diode and the second type of device is a transistor. 
     
     
         7 . The semiconductor product of  claim 1  wherein the first active region is formed from a portion of the semiconductor layer to which silicon has been added. 
     
     
         8 . The semiconductor product of  claim 7 , wherein the first active region is formed by selective epitaxial growth of silicon on the semiconductor layer. 
     
     
         9 . The semiconductor product of  claim 7 , wherein a diode is formed on at least a portion of the first active region. 
     
     
         10 . The semiconductor product of  claim 7 , wherein a transistor is formed on at least a portion of the second active region. 
     
     
         11 . The semiconductor product of  claim 7 , wherein a first type of device is formed on at least a portion of the first active region and a second type of device is formed on at least a portion of the second active region. 
     
     
         12 . The semiconductor product of  claim 11 , wherein the first type of device is a diode and the second type of device is a transistor. 
     
     
         13 . The semiconductor product of  claim 1  wherein the semiconductor layer consists essentially of silicon germanium. 
     
     
         14 . The semiconductor product of  claim 1  wherein the semiconductor layer consists essentially of silicon. 
     
     
         15 . A semiconductor product, comprising:
 a semiconductor layer consisting essentially of silicon or silicon germanium with different active thicknesses on a single substrate;   the semiconductor layer comprising a first active region having a first thickness less than an initial thickness and a second active region having a second thickness no less than the initial thickness; and   the first active region being formed from a portion of the semiconductor layer from which silicon has been removed.   
     
     
         16 . A semiconductor product, comprising:
 a semiconductor layer consisting essentially of silicon or silicon germanium with different active thicknesses on a single substrate;   the semiconductor layer comprising a first active region having a first thickness and a second active region having a second thickness greater than the first thickness;   the first active region being formed from a portion of the semiconductor layer from which silicon has been removed; and   the second active region being formed from a portion of the semiconductor layer to which silicon has been added.   
     
     
         17 . The semiconductor product of  claim 16 , wherein the second active region is formed by selective epitaxial growth of silicon on the semiconductor layer and a diode is formed on at least a portion of the second active region. 
     
     
         18 . The semiconductor product of  claim 16 , wherein the first active region is formed by removing silicon from the semiconductor layer by performing local oxidation of silicon and a transistor is formed on at least a portion of the first active region. 
     
     
         19 . The semiconductor product of  claim 16 , wherein a first type of device is formed on at least a portion of the first active region and a second type of device is formed on at least a portion of the second active region. 
     
     
         20 . The semiconductor product of  claim 19 , wherein the first type of device is a transistor and the second type of device is a diode.