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Method for laser trench filling with a tough compliant material

IP.com Disclosure Number: IPCOM000007136D
Publication Date: 2002-Feb-27
Document File: 2 page(s) / 58K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for laser trench filling with a tough compliant material. Benefits include improved reliability and improved yield.

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Method for laser trench filling with a tough compliant material

Disclosed is a method for laser trench filling with a tough compliant material. Benefits include improved reliability and improved yield.

Background

      Silicon thin film can crack and delaminate from damage at the edges and corners of a die from cutting with a saw. The wafer damage can be minimized by using a laser trench cut close to the die guard ring prior to the saw cut (see Figure 1). However, damage from the laser trench, though less severe, can also initiate cracks, especially when package stresses are high as is the case in large-die applications.

      If the laser trench is not completely filled with the underfill material, voids in the trench can cause stress concentration that can initiate cracks from laser cut damage regions.

              No conventional solution for this problem exists. The problem is expected to get worse with larger die applications.

General description

      The disclosed method utilizes laser trenches adjacent to the guard ring to prevent Si cracks from propagating into the Si active circuitry from saw damage defects. However, damage to the Si from the laser cut can initiate cracks. Damage from the laser trench can be repaired by filling the laser trench with a tough compliant material.

      The key elements of the method are:

•             Defects/cracks to the Si thin films at laser trench locations are repaired by filling the cracks with a tough compliant material.

•             Stress concentration at the defects or cracks is reduced by t...