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MOSFET Structures Using Selective Epitaxial Growth

IP.com Disclosure Number: IPCOM000074275D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Terman, LM: AUTHOR

Abstract

A method for fabricating a MOSFET device with the gate connected to the drain load without a drain diffusion is disclosed. The technique is extended to MOSFET circuits fabricated without diffusion steps. However, this latter approach loses some of the density advantages of the diode connected device.

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MOSFET Structures Using Selective Epitaxial Growth

A method for fabricating a MOSFET device with the gate connected to the drain load without a drain diffusion is disclosed. The technique is extended to MOSFET circuits fabricated without diffusion steps. However, this latter approach loses some of the density advantages of the diode connected device.

A MOSFET is shown in A connected to operate in a diode-like mode. Device 1 is formed in the usual manner except that a drain diffusion is not performed during the usual diffusion step in the fabrication of FET's which forms the N/+/ source region 2. After formation of the thin-gate oxide region 3, a drain opening is made in the gate oxide and an N-type region 4 of silicon is epitaxially deposited on the surface of P-conductivity type wafer 5. After the epitaxial deposition of region 4, a certain amount of the epitaxially deposited N- conductivity material of region 4 diffuses into P-conductivity type wafer 5. Gate metallization 6 is then deposited and delineated by well-known photolithographic and etching techniques along with a metallic extension 7 thereof which contacts epitaxially deposited region 4. Thus, when device 1 is turned on, the N-type channel region formed makes contact with epitaxially deposited region 4, and no separate drain diffusion is required. The advantage of this structure is that self- alignment of the contact region with diffused portion 4 results in reduced area requirements.

A diffusionless MOSFET device is shown in B. The source and drain regions 11, 12, respectively, are made by selective epitaxial growth Since source and drain regions 11, 12, respectively, can...