Page 361 - A Practical Guide from Design Planning to Manufacturing

Chapter
11

Silicon Debug and Test

Overview
This chapter discusses how completed die are tested. The chapter
describes the validation of the design, the root causes and the fixing of
design bugs, and the testing flow to identify manufacturing defects.

Objectives
Upon completion of this chapter the reader will be able to:

1. Understand the importance of design for test (DFT) circuits.
2. Understand how scan sequentials are used.
3. Describe the different types of silicon bugs.
4. Understand how a shmoo diagram is used in debug.
5. Describe some of the tools used in silicon debug.
6. Describe the different ways of fixing silicon bugs.
7. Understand the silicon test flow used to identify manufacturing defects.

Introduction

The most exciting single day in the life of any semiconductor product is
first silicon, the day when the first chips complete fabrication. This day
comes after what may have been years of simulation and is a suspenseful
test of whether anything crucial has been overlooked in the design or
fabrication of the product. Some of these first chips are immediately
packaged and plugged into circuit boards for testing. While engineers
cross their fingers and hold their breath, the product is powered up for

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