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Concept Search - What can I type?
For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.
Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.
A low temperature fabrication technique for bipolar transistors which permit
full utilization of submicron geometries in device design is described below.
The method starts with forming a thin single-crystal silicon membrane, for
example, by doping the top surface of a silicon film with boron and then etching
off the substrate with an ethylenediamine-pyrocatechol etching system. The
resultant membrane is then annealed at an elevated temperature to drive out the
remaining boron. A layer of silicon oxynitride 10 is then deposited on the
backside of the membrane 12, as shown in Fig. 1, to form a stress-free support
layer. The silicon membrane is selectively oxidized to form the isolation regions 14. The remaining silicon is doped to become n-type. An oxide mask 16 is
grown, and regions 18 are doped n/x/.
As shown in Fig. 2, a n/x/ chemical vapor deposited (CVD)
polysilicon pattern 20 is formed over the regions 18. A CVD layer of
silicon dioxide 22 is formed over the poly-silicon pattern 20. An
opening 24 is made in the oxide layer 16. As shown in Fig. 3, a
p/+/ CVD poly-silicon pattern 26 is formed. A p-dopant is evaporated
or shallowly implanted into the base region 28 (about 100 Angstroms).
A CVD layer 30 of silicon dioxide is then formed over the structure.
An emitter hole 32 is etched in the layer 30.
As shown in Fig. 4, a pattern 34 of n/+/ poly-silicon for the emitter is formed.
The base and the emitter pol...