Chemical etch solution and technique for imaging a device's shallow junction profile

Abstract

The present invention provides, in one aspect, a method of imaging a microelectronics device 100 . The method comprises cleaning, when contaminants are preset, a sample of a microelectronics device 100 to be imaged with a first solution comprising hydrofluoric acid, an inorganic acid and water, exposing the sample to a second solution comprising hydrofluoric acid, an inorganic acid and an organic acid, wherein the second solution forms a contrast between different regions within the sample, and producing an image of the contrasted sample.

1 . A method of imaging a junction profile of a microelectronics device, comprising: 
 cleaning a sample of a microelectronics device to be imaged with a first solution comprising hydrofluoric acid, an inorganic acid and water;    exposing the sample to a second solution comprising hydrofluoric acid, an inorganic acid and an organic acid, the second solution forming a contrast between different regions within the sample; and    producing an image of the sample.    
   
   
       2 . The method as recited in  claim 1 , wherein the inorganic acid is a strong inorganic acid having a pK a  of about −1.0 or less and the organic acid is a weak acid having a pK a  of about 2.76 or greater.  
   
   
       3 . The method as recited in  claim 2  wherein the inorganic acid of the first and second solutions is nitric acid and the organic acid is acetic acid.  
   
   
       4 . The method as recited in  claim 2 , wherein the inorganic acid is hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, or sulfuric acid.  
   
   
       5 . The method as recited in  claim 2 , wherein the organic acid is butonoic acid, formic acid, or propinoic acid.  
   
   
       6 . The method as recited in  claim 1 , wherein the first solution is a solution of from about 1 to about 3 parts by volume of 5% hydrofluoric acid, from about 2 parts to about 4 parts by volume of 70% nitric acid, and from about 4 parts to about 6 parts by volume of water.  
   
   
       7 . The method as recited in  claim 6 , wherein the second solution is a solution of from about 1 part to about 3 parts by volume of 5% hydrofluoric acid, from about 2 parts to about 4 parts by volume of 70% nitric acid, and from about 4 parts to about 6 parts by volume of 99% acetic acid.  
   
   
       8 . The method as recited in  claim 1 , wherein cleaning includes placing the sample into the first solution for a period of time ranging from about 15 seconds to about 20 seconds and at a temperature ranging from about 22 to about 30 degrees centigrade.  
   
   
       9 . The method as recited in  claim 1 , wherein exposing includes placing the sample into the second solution for a period of time ranging from about 3 seconds to about 16 seconds and at a temperature ranging from about 22 to about 30 degrees centigrade.  
   
   
       10 . The method as recited in  claim 1 , wherein producing an image includes producing an image of the sample with a transmission electron microscope, a scanning electron microscope or a focused ion beam microscope.