Pedestal transistors and method of production thereof
AssigneeMotorola, Inc.
InventorIsrael A. Lesk
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Abstract
The present invention describes a method of producing an MOS, bipolar and Bimos pedestal transistor wherein the source, drain, and gate metals are in place prior to the source/drain diffusion in a MOS transistor; and the emitter and base metals are in place before junction formation on the bipolar transistors. This is accomplished in MOS devices by a first blanket implantation of impurities into a first polysilicon layer during processing and a second blanket implantation into a second polysilicon layer subsequent to deposition of the metal layers. This is accomplished in bipolar devices by the above, or by blanket implantations subsequent to the deposition of the metal layers.
Claims22
A method of producing an MOS pedestal transistor comprising the steps:
- forming a substrate having a pedestal;
- depositing a first polysilicon layer of a first conductivity type;
- depositing a first tungsten silicide layer on said first polysilicon layer;
- depositing a silicon dioxide layer on said first tungsten silicide layer;
- producing an opening through said silicon dioxide, first tungsten silicide, and first polysilicon layers to said pedestal of said substrate, said opening being defined by a side wall;
- forming a gate dielectric on said pedestal;
- forming a side wall insulator about said side wall defining said opening;
- depositing a second polysilicon layer;
- depositing a second tungsten silicide layer on said second polysilicon layer;
- baking said MOS pedestal transistor causing a portion of said first impurity of said first polysilicon layer to diffuse into a portion of said pedestal;
- and
- implanting a second impurity into said second polysilicon layer.
A method of producing a Bipolar pedestal transistor comprising the steps:
- forming a substrate having a pedestal;
- depositing a first polysilicon layer;
- depositing a first tungsten silicide layer on said first polysilicon layer;
- depositing a silicon dioxide layer on said first tungsten silicide layer;
- producing an opening through said silicon dioxide, first tungsten silicide, and first polysilicon layers to said pedestal of said substrate, said opening being defined by a side wall;
- forming a side wall insulator about said side wall defining said opening;
- depositing a second polysilicon layer;
- depositing a second tungsten silicide layer on said second polysilicon layer;
- forming a base;
- and
- forming an emitter.
A method of producing a Bimos pedestal transistor comprising the steps:
- forming a substrate having a first and a second pedestal;
- depositing a first polysilicon layer of a first conductivity type;
- depositing a first tungsten silicide layer on said first polysilicon layer;
- depositing a silicon dioxide layer on said first tungsten silicide layer;
- producing a first and a second opening through said silicon dioxide, first tungsten silicide, and first polysilicon layers to said first and second pedestals of said substrate, each of said first and second openings being defined by side walls;
- forming a gate dielectric on said first pedestal;
- forming a side wall insulator about each of said side walls defining said first and second openings;
- depositing a second polysilicon layer;
- depositing a second tungsten silicide layer on said second polysilicon layer;
- baking said Bimos pedestal transistor causing a portion of said first impurity of said first polysilicon layer to diffuse into a portion of said first and second pedestals adjacent said first polysilicon layer;
- and
- implanting a second impurity of a first conductivity type into said second polysilicon layer;
- diffusing said second impurity through said second polysilicon layer into a base portion of said second pedestal adjacent to said second polysilicon layer;
- implanting a third impurity of a second conductivity type into a Bipolar portion of said second polysilicon layer;
- and
- diffusing said third impurity through said second polysilicon layer into an emitter portion of said second pedestal adjacent to said second polysilicon layer.
Dependencies are inferred from the claim text.