HV complementary bipolar transistors with lateral collectors on SOI with resurf regions under buried oxide
Complementary high-voltage bipolar transistors in silicon-on-insulator (SOI) integrated circuits is disclosed. In one disclosed embodiment, a collector region is formed in an epitaxial silicon layer disposed over a buried insulator layer. A base region and an emitter are disposed over the collector region. An n-type region is formed under the buried insulator layer (BOX) by implanting donor impurity through the active region of substrate and BOX into a p-substrate. Later in the process flow this n-type region is connected from the top by doped poly-silicon plug and is biased at Vcc. In this case it will deplete lateral portion of PNP collector region and hence, will increase its BV.
1. An integrated circuit, comprising:
a PNP structure, including a first p-type layer, an n-type layer under the first p-type layer, and a second p-type layer under the n-type layer;
an insulator layer under the second p-type layer;
an n-type buried region under the PNP structure and the insulator layer; and
a conductive plug extending from a surface aligning with the second p-type layer to reach the n-type buried region.
2. The integrated circuit of claim 1 , wherein the conductive plug includes an n-type polysilicon plug.
3. The integrated circuit of claim 1 , further comprising:
a NPN structure having a first n-type layer, a p-type layer under the first n-type layer, and a second n-type layer under the p-type layer; and
a deep trench structure extending from the surface to the insulator layer and separating the NPN structure from the PNP structure.
4. The integrated circuit of claim 3 , wherein the n-type buried region terminated without extending under the NPN structure.
5. The integrated circuit of claim 1 , further comprising:
a deep trench structure extending from the surface to the insulator layer and laterally surrounding the second p-type layer of the PNP structure.
6. The integrated circuit of claim 1 , further comprising:
a second conductive plug extending from the surface to a p-type substrate under the n-type buried layer, the second conductive plug configured to transfer a ground voltage to the p-type substrate.
7. The integrated circuit of claim 6 , wherein the second conductive plug includes a p-type polysilicon plug.