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Quench Test for Ascertaining Quartz Cracking Susceptability

IP.com Disclosure Number: IPCOM000051965D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 31K

Publishing Venue

IBM

Related People

Barton, PJ: AUTHOR [+3]

Abstract

The approach here for ascertaining quartz (coated on semiconductor wafers)-cracking susceptibility, comprises subjecting a wafer through a H(2) reflow cycle after CrCuAu land deposition prior to PbSn solder mound evaporation and subsequent quartz crack inspection. For very crack-sensitive wafers such as the wafers with sharp-edged metallurgy, thermal treatment provided in the reflow cycle is sufficient to cause quartz cracking, which has been observed.

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Quench Test for Ascertaining Quartz Cracking Susceptability

The approach here for ascertaining quartz (coated on semiconductor wafers)-cracking susceptibility, comprises subjecting a wafer through a H(2) reflow cycle after CrCuAu land deposition prior to PbSn solder mound evaporation and subsequent quartz crack inspection. For very crack-sensitive wafers such as the wafers with sharp-edged metallurgy, thermal treatment provided in the reflow cycle is sufficient to cause quartz cracking, which has been observed.

Wafer runs in manufacturing can be monitored continuously as to their quartz-cracking susceptibility by having a few chip sites in a wafer blocked out prior to PbSn evaporation. Subsequently, the wafer may proceed with the normal process flow until after H(2) reflow. Crack inspection by IR or by etch and inspect method after H(2) reflow will determine the crack sensitivity of particular wafer batches. This test method will eliminate the expensive process of PIT (piston impact test) needed for the present crack-sensitivity test. Thus, the quench method may be used to screen quartz crack-sensitive wafer batches. In fact, this method will specifically evaluate the quality of a quartz-BLM (ball limiting metallurgy) combination including the land size and stress, edge feathering, via hole size and geometry, quartz quality without introducing additional uncontrollable variables, as it is presently done in PIT to determine crack sensitivity.

Less crack-sensitive wafers, such as those with metal mask-formed metallurgy, need a variation in quench procedure to bring out cracking. +Here, the wafers are heated to about 350 degrees C for 2 minute...