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A METHOD FOR INSITU DETECTION OF PLANARIZATION IN CHEMICAL MECHANICAL POLISHING

IP.com Disclosure Number: IPCOM000004653D
Original Publication Date: 2001-Mar-19
Included in the Prior Art Database: 2001-Mar-19
Document File: 2 page(s) / 7K

Publishing Venue

Motorola

Related People

Thomas Kobayashi: AUTHOR [+2]

Related Documents

US 5,461,007: PATENT [+2]

Abstract

A METHOD FOR INSITU DETECTION OF PLANARIZATION IN CHEMICAL MECHANICAL POLISHING

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A METHOD FOR INSITU DETECTION OF PLANARIZATION IN CHEMICAL MECHANICAL POLISHING

by Thomas Kobayashi and Charles Stager

Chemical Mechanical Polishing (CMP) is a process in semiconductor manufacture used for removing topography by removing material from the wafer surface. One of the reasons for doing this is to planarize the wafer to reduce depth of focus issues at photolithography. Many methods have been developed for end pointing the process.

Current end point technology is the measurement of thickness, correlated with historical data to determine planarization. This has the disadvantage that the outcome is convoluted with tool set up conditions, that is the hardness of the pad (or some other condition) as well as the amount polished will help determine the ultimate planarity. Without the historical data link, the measurement in and of itself is not sufficient to determine if the process has completed.

There are two other methods available to measure removal or revelation of edges. (Kobayashi, Process for polishing and analyzing a layer over a patterned semiconductor substrate #5461007, Kobayashi, Process for polishing and analyzing an exposed surface of a patterned semiconductor substrate #5691253) These are not currently available commercially available and are limited to ex-situ use.

An alternative to the above would be a system able to detect degree of planarization and recessed defects on the wafer surface during CMP process by measuring the amount of slurry trapped between the wafer and the pad.

A chemically inert additive could be dispersed into the slurry that will make its presence easily detectable during polish. It should be inert so as not to adversely effect the polish. The material will then fill in any recesses on the wafer face along with the slurry. As the wafer polishes, the recess volume will decrease, eventually reducing the material trapped between the pad and the wafer to a minimum. The minimal presence of the material will indicate an absence of depressions. This could help detect scratches or point defects as well as topography.

In one form, the additive would be a dye that could be detected by absorption of a specific color. Another form might be a chemical that would fluoresce under the correct conditions. (i.e. light source of the proper wavelength, heat, some other form of radiation.) Yet another form could be a radioactive tracer. So long as the dispersal is uniform within the slurry, the ability to quantitatively determine the amount of slurry between the wafer and the pad would give a direct measure of the volume and therefor the planarity of the wafer.

The case of a fluorescent dye is probably the most advantageous. It can be adapted to existing consumable sets with a minimum of problems. The methods exist to allow this method to be used in-situ (window pads). The signal is one of specific wavelength, allowing for filtering and boosting of the signal. It is insensitive to the type or color of the substrate since the domina...