Crystal Growth and Evaluation of Silicon for VLSI and ULSI

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5

From Silicon Ingots to Silicon Wafers

5.1 Introduction

Once the silicon crystal is grown, the silicon ingot is sliced into thin wafers—most of them

no greater than 1 mm thickness. Since silicon is a hard, brittle material, special materials

are needed to shape it to the desired levels. Industrial-grade diamonds, SiC, and Al

2

O

3

are

often used for this purpose. The conversion of silicon ingots into nal polished wafers

requires at least six machining operations, two chemical operations, and one or two pol-

ishing operations, depending on whether the wafers are to be polished only on one side

or both sides. Figure 5.1 shows fully grown single- ...