摘要 |
<p>A wafer structure is deposited on a composite substrate structure having at least two substrate layers bonded together. A first substrate layer is made of a first substrate material having a first-substrate-layer material transverse coefficient of thermal expansion, greater than the wafer transverse coefficient of thermal expansion, and a second substrate layer is made of a second substrate material having a second-substrate-layer material transverse coefficient of thermal expansion, measured parallel to the transverse direction, less than the wafer transverse coefficient of thermal expansion. The substrate layers are present in relative proportions such that the substrate transverse coefficient of thermal expansion differs from the wafer transverse coefficient of thermal expansion by not more than about 2x10<SUP>-6</SUP>/° F.</p> |