Die preparation

From ArticleWorld

Die preparation is a process used in semiconductor device fabrication in which a wafer is prepared for assembly in IC packages by singulating it into individual dice. This process typically consists of two major steps; namely, wafer mounting and semiconductor die cutting (also known as die cutting, dicing and wafer sawing).

Wafer mounting

During this process, the wafer is attached along with a wafer frame onto a dicing tape. The wafer frame is a ring made of tough plastic or metal. The dicing tape is a strong and flexible plastic sheet 0.08 mm thick with an adhesive applied on one side in order to hold the wafer and wafer frame in place. A special wafer mounting machine is used in this process.

The wafer mounting process thus can be summarized as involving the following steps:

1. Loading of the frame.
2. Loading of the wafer.
3. Application of the tape to the wafer and the wafer frame. Care is taken to ensure that there are no trapped air bubbles during the application of the tape.
4. Removal of the excess tape.
5. Unloading of the mounted wafer.

Semiconductor-die cutting

This process follows wafer mounting and it involves the cutting up of the wafer (which contains multiple ICs) into individual dice (containing one IC each). This is done to prepare them for the IC assembly.

A thin spacing called a scribe is maintained so that the saw which is used can cut the wafer safely without causing damage to the delicate circuit. Since the scribe is very thin, just about 100 pm, the saw used has to be very thin and accurate.

This process thus involves the following steps:

1. The frame is aligned so as to make it suitable for cutting.
2. With the help of a diamond wheel cutter, the wafer is then cut to the programmed dimensions.
3. The wafer is made to go through cleaning using a spray of water.