David:
SIMOX implanters are optimized for oxygen implantation, but could probably be used for other species (such as nitrogen) to create a buried layer. In fact, in the early days of SOI, some people looked at using a buried nitride layer for SOI. There are some problems with it, however: it does not reflow as well as silicon dioxide - resulting in interfaces that are more uneven, nitrides trap charge worse than oxides, nitride has a worse thermal expansion mismatch to silicon than oxide - creating wafer warpage concerns, nitride has a higher dielectric constant than oxide - resulting in more capacitance for a given SOI thickness... For SOI implantation, oxygen and nitrogen are the only two species i have seen proposed. For bonded wafers, there are more options, such as using buffer layers, but they add to the cost.
IBM is clearly doing work on SOI, the question is whether the recent technology family announcement is related to SOI.
Keith |
