Low species buffered rinsing fluids and methods

Abstract

A method of rinsing an electronic substrate recognizes that adding a buffer to a rinsing fluid eliminates fluctuations in the amount of residues on an electronic substrate, and a buffered rinsing fluid is prepared by (a) providing water from a water source; (b) deionizing the water to produce deionized water; (c) adding a buffer to the deionized water at a concentration effective to eliminate fluctuations in the amount of residues on the electronic substrate. The electronic substrate is rinsed with the buffered rinsing fluid.

What is claimed is:  
     
         1 . A method of rinsing an electronic substrate, comprising: 
 recognizing that fluctuations in the amount of residues on an electronic substrate are eliminated by adding a low species buffer to a rinsing fluid;    preparing a low species buffered rinsing fluid by (a) providing water from a water source; (b) deionizing the water to produce deionized water; (c) adding a buffer to the deionized water at a concentration effective to eliminate fluctuations in the amount of residues on the electronic substrate; and    rinsing the electronic substrate with the low species buffered rinsing fluid.    
     
     
         2 . The method of  claim 1  wherein the residue comprises an etchant.  
     
     
         3 . The method of  claim 1  wherein the residue comprises copper.  
     
     
         4 . The method of  claim 1  wherein the residue comprises particulate material.  
     
     
         5 . The method of  claim 1  wherein the electronic substrate comprises an electronic interconnect structure.  
     
     
         6 . The method of  claim 1  wherein the electronic substrate comprises an integrated circuit.  
     
     
         7 . The method of  claim 1  wherein the electronic substrate comprises a printed circuit board.  
     
     
         8 . The method of  claim 1  wherein the low species buffer comprises an amphoteric buffer.  
     
     
         9 . The method of  claim 1  wherein the low species buffer comprises an acid and a salt of the acid.  
     
     
         10 . The method of  claim 1  wherein the low species buffer comprises at least one of sodium bicarbonate or potassium bicarbonate.  
     
     
         11 . The method of  claim 1  wherein the pH of the low species buffered fluid is between 7-14.  
     
     
         12 . The method of  claim 1  wherein the pH of the low species buffered fluid is between 7.5-9.0.  
     
     
         13 . The method of  claim 1  wherein the concentration of the buffer is between 100 ppm and 1000 ppm.  
     
     
         14 . The method of  claim 1  wherein the concentration of the buffer is between 400 ppm and 500 ppm.  
     
     
         15 . The method of  claim 1  wherein the rinsing comprises spray rinsing.  
     
     
         16 . The method of  claim 1  wherein the rinsing comprises immersion rinsing.  
     
     
         17 . An intermediate comprising: 
 a printed circuit board having residues from an etching step; and    a solution of deionized water and buffer contacting the printed circuit board in a bath.    
     
     
         18 . The intermediate of  claim 17  wherein the buffer comprises sodium bicarbonate.  
     
     
         19 . The intermediate of  claim 18  wherein the buffer has a concentration of between 400 ppm and 500 ppm.  
     
     
         20 . The intermediate of  claim 17  wherein the solution has a pH of between about 7.0 and 9.0.