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Compact Device for Gas Injection to Improve the Quality of the Laser Scribe and Dicing on Multi-Layer Semiconductor Wafers

IP.com Disclosure Number: IPCOM000101588D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 204K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that injects gas downstream on a multi-layer semiconductor wafer laser beam to enhance laser scribing and dicing. Benefits include reducing scribe defects.

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Compact Device for Gas Injection to Improve the Quality of the Laser Scribe and Dicing on Multi-Layer Semiconductor Wafers

Disclosed is a method that injects gas downstream on a multi-layer semiconductor wafer laser beam to enhance laser scribing and dicing. Benefits include reducing scribe defects.

Background

The laser beam used for scribing and/or dicing creates plasma and can cause cracks and delaminations on a semiconductor wafer. Plasma shielding of the laser beam prevents laser-wafer interactions and creates an enlarged Heat Affected Zone (HAZ) on the wafer; the HAZ is a potential cause of failure due to the die preparation process.

In order to overcome the plasma shielding effect, elevated laser pulse energies are used for wafer dicing that cause an enlarged HAZ. Steering the laser beam in turbulent vapor clouds and plasma causes the scribe and/or dice trenches on the wafer to seem “wavy”.  This “wavy” scribe problem is currently solved by placing an exhaust port above the wafer, so that exhaust gas and vapors are forced upstream, minimizing turbulence in the laser beam incidence direction. This creates a strong differential pressure gradient along the laser plasma plume. The top of the plume experiences lower pressure and this causes the plasma, gases and vapors to increase in volume and cool down, breaking up the plasma.

General Description

The current state of art is shown in Figure 1. The exhaust port is placed in close proximity to the wafer. The laser beam reaches the work piece through two holes drilled in the exhaust port. The top hole is smaller, and allows a focused beam to enter the port. The bottom hole is larger and allows for the evacuation of exhaust gases and vapors. This exhaust principle is important to get rid of the “wavy” scribe.

The disclosed method is shown in Figure 2. All the principles and existing equipment are used in the disclosed method...