Semiconductor Manufacturing – Quick Overview

Many admit that semiconductor manufacturing is the most complex and difficult manufacturing process that exist today. We agree. There are several ways to describe the Semiconductor manufacturing flow, but they are all boiled down to a very basic diagram.

The following diagram is a simplified flow describing the semiconductor manufacturing process.

The very first step in the manufacturing process is sourcing the wafers from a semiconductor foundries (fab). The fab has a lead time of 2-4 months and therefore in some of the cases companies keep wafers on stock to allow quick turnaround in the future (e.g. buffer).

The next step is wafer testing (wafer sort). There are 2 reasons for wafer sort: to check whether the wafer yield meets the production target and to label the bad dies. Wafer test is not always a necessary step. In low volume applications, wafer sort is often skipped. Wafer sort is a relatively quick step and can take 2-4 weeks depending on your batch size.

Following that step, the wafers are assembled. The assembly house will take the good dies from each wafer and assemble them into the designated package. Provided that all the necessary material is available at the assembly house – the packaging phase will take 1-3 weeks. Both QFN and BGA package types would need a leadframe or a substrate to be able to assemble die. Therefore, you may want to make sure that they are available at the assembly house.

Now the dies are available in their final package. But it’s not a good idea to ship them to the end customer.

The last step in the semiconductor manufacturing process is to test the chips to ensure the end-customer is receiving good-tested-chips. The final test is a last step in the manufacturing process and can take 2-4 weeks depending on the batch size. The final test step is often a more comprehensive test compared to the wafer sort and covers all chip functionality and connectivity.

Now the chips are split into two bins: good and bad dies. The good dies are ready to be shipped to the customer or store in storage. They bad dies are scrapped.