The invention discloses a method for manufacturing a high-performance double-layer polysilicon bipolar
transistor. The method comprises the following steps that 1),
LOCOS and CVD are adopted to deposit SiO2 to form a composite isolation structure, and high-temperature
process time is reduced; 2), the SiO2 is used as an
etching stopping layer of base polysilicon, and
etching damage is avoided; 3), a composite side wall structure is formed through SiO2 and N+polysilicon, and emitter resistance is reduced. The method has the advantages that on the premise of not lowering the
isolation effect, the high-temperature
process time is reduced, therefore, a relatively thin epitaxial layer can be adopted, the better
microwave performance is obtained, SiO2 is adopted as the
etching stopping layer, the etching damage to the
silicon epitaxial layer is eliminated, breakdown characteristics are improved, current amplifying coefficients are increased, and
noise coefficients are reduced. The composite side wall structure with SiO2 and N+polysilicon is adopted, it can be guaranteed that emitter-base electric isolation is carried out, and meanwhile the emitter resistance is lowered, the current amplifying coefficients are increased, and the
noise coefficients are reduced.