Patent attributes
The methods and apparatus disclosed herein concern a process that may be referred to as a “soft anneal.” A soft anneal provides various benefits. Fundamentally, it reduces the internal stress in one or more silicon layers of a work piece. Typically, though not necessarily, the internal stress is a compressive stress. A particularly beneficial application of a soft anneal is in reduction of internal stress in a stack containing two or more layers of silicon. Often, the internal stress of a layer or group of layers in a stack is manifest as wafer bow. The soft anneal process can be used to reduce compressive bow in stacks containing silicon. The soft anneal process may be performed without causing the silicon in the stack to become activated.
