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Method for waxing and dicing for wafer sawing

IP.com Disclosure Number: IPCOM000021722D
Publication Date: 2004-Feb-04
Document File: 4 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for waxing and dicing for wafer sawing. Benefits include improved functionality, improved performance, improved yield, and improved ease of implementation.

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Method for waxing and dicing for wafer sawing

Disclosed is a method for waxing and dicing for wafer sawing. Benefits include improved functionality, improved performance, improved yield, and improved ease of implementation.

Background

Die chipping and cracking occurs during wafer sawing of the exposed, active (top) surface of 3-mil (~76-micron) thick silicon wafers when the edges of the wafer are unprotected. (see Figure 1).

         Conventional wafer sawing steps after thinning the wafer include the following (see Figure 2):

1.         Laminate with adhesive film and dicing tape on the bottom side of wafer.

2.         Detape (peel off) the wafer back-side grinding tape and expose the active surface of the silicon wafer.

3.         Dice through the release liner. The top surface is exposed and unprotected. During the dicing process, the die edges can chip due to the mechanical sawing effect.

4.         Pick-and-place the die.

Conventional techniques to resolve the die chipping and cracking problem during wafer sawing and pick-and-place movement include the following:

•         Optimize the saw speed and depth to minimize the die chipping

•         Use low-adhesive film to reduce the adhesion between the adhesive film and silicon wafer, where the die can be picked up easily.

These techniques reduce the die cracking problem, but die chipping is still a concern, especially when sawing extremely thin (3-mil thick) silicon wafers.

General description

The disclosed method deposits a layer of thermoplastic wax on the top surface of ~3-mil to 5‑mil thick silicon wafers to prevent wafer chipping and cracking during wafer sawing.

         The key elements of the method include:

•         Spinning a coating layer of transparent, molten thermoplastic mounting wax on the top surface of a ~3‑mil to 5-mil thick silicon wafer

•         Thickness of the wax layer at 10-20 microns to ensure good alignment during dicing

-         Evenness

-         Absence of bubbles

-         Formation of a hard layer

Advantages

         The disclosed method provides advantages, including:

•         Improved functionality due to ensuring the correct alignment of the saw on the sawing path because the thermoplastic mounting wax is transparent

•         Improved performance due to depositing an even, flat, hard, and bubble-free holding layer on the silicon-wafer surface by controlling the spraying pressure, time, and temperature

•...