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Manufacturing Low Noise High Frequency Bipolar Transistors for Analog Circuits

IP.com Disclosure Number: IPCOM000077470D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Collins, TW: AUTHOR

Abstract

A method is described for the manufacture of low noise - high frequency bipolar transistors for use in analog circuits, which enhance the base diffusion in the extrinsic region of the device without performing the extra base diffusion now used in the prior art.

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Manufacturing Low Noise High Frequency Bipolar Transistors for Analog Circuits

A method is described for the manufacture of low noise - high frequency bipolar transistors for use in analog circuits, which enhance the base diffusion in the extrinsic region of the device without performing the extra base diffusion now used in the prior art.

Step one: Predeposit P-type boron in an N-type substrate 3 and forming boron rich glass 1 over the area 2 in which the boron was predeposited.

Step two: Remove the boron glass from the areas 4 in which it is undesired to have a constant doping source present at the surface of the boron predeposition area, during the base diffusion drive-in operation.

Step 3: Perform the oxidation and base drive-in operation, wherein the boron rich glass 1 acts as a constant diffusion source and creates the diffusion profile 5 5, as shown in step 3 3.

Step 4 encompasses the removal of the boron glass and silicon dioxide from step 3. Further, emitted diffusion and ohmic contacts 6 are made by standard techniques.

This method provides low-base resistance by obtaining an enhanced base diffusion under the base contacts, by the use of a constant-source diffusion provided by the boron glass. The high-frequency characteristic is obtained by using a limited source under the emitter, and is further increased by the fact that the enhanced base diffusion under the base contacts stored charge in the extrinsic base region.

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