Patent ID: 6121111
Filing Date: 2000-09-19
Classification: H01L

Abstract:
A method of removing tungsten from the edge of a wafer, comprising:providing a wafer having an outer edge, active regions, alignment regions, and alignment marks, wherein said alignment masks are located in said alignment regions;providing a layer of dielectric material, having a top surface and a plurality of via holes formed therein, on said wafer, thereby covering said alignment marks with said dielectric material;depositing a layer of first conductor material on said layer of dielectric material thereby filling said via holes with said first conductor material;planarizing said wafer using chemical mechanical polishing thereby removing said first conductor material from said top surface of said layer of dielectric material and leaving said first conductor material in said via holes and at said outer edge of said wafer;depositing a layer of second conductor material on said wafer after planarizing said wafer using a means whereby none of said second conductor material is deposited on said outer edge of said wafer;forming a layer of photoresist on said wafer after depositing said layer of second conductor material;patterning said layer of photoresist thereby removing said photoresist from said alignment region of said wafer;removing said photoresist from said outer edge of said wafer;etching away said second conductor material from said alignment region of said wafer after patterning said layer of photoresist;etching away said first conductor material from said outer edge of said wafer after removing said photoresist from said outer edge of said wafer; andremoving the remaining said photoresist from said wafer.