Browse Prior Art Database

VSS SUBSTRATE TIE PLUS BURIED LAYER FOR RF IMPROVEMENTS

IP.com Disclosure Number: IPCOM000009851D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-24
Document File: 2 page(s) / 87K

Publishing Venue

Motorola

Related People

Craig Jasper: AUTHOR [+3]

Abstract

The manufacturability and performance of RF devices depends on several key parameters. For example, obtaining good isolation and making a low ohmic contact to a heavily doped buried layer and substrate is critical. The buried layer is fonned by implanting, followed by a drive-in cycle, or a doped Epi layer. The formation of the isolation layer is typically formed by a heavily doped trench making contact to a buried layer.

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MOTOROLA

Technical Developments

VSS SUBSTRATE TIE PLUS BURIED LAYER FOR RF IMPROVEMENTS

by Craig Jasper, Dragan Zupac and Vida Ilderem

BACKGROUND

The manufacturability and performance of RF devices depends on several key parameters. For example, obtaining good isolation and making a low ohmic contact to a heavily doped buried layer and substrate is critical. The buried layer is fonned by implanting, followed by a drive-in cycle, or a doped Epi layer. The formation of the isolation layer is typically formed by a heavily doped trench making contact to a buried layer.

The fonnation of these structures is expensive to manufacture and not easy to adjust or change, thus making optimization difficult.

PROBLEM

RF noise is described by using the block dia~ gram shown in Figure 1. The substrate to buried layer resistance is illustrated by resistors R1 and R5, and buried layer resistance is illustrated by resistor R3. The resistance values of resistors Rl, R3, and RS determine the electrical performance of the device. The ability to control these resistance val~ ues is critical in achieving optimal device perfor~ mance.

IC manufactures need a low cost way to manufacture and independently adjust the buried layer resistance while still maintaining a low ohmic contact to the substrate. The current process is typically done by using a buried layer having a doped trench for contacting the substrate. This process has approximately 15 steps that are time consuming, expensive, and complex.

Motorola. Inc. 2000

SOLUTION

A cost competitive solution includes an implanted buried layer with an implanted vertical substrate tie or sinker implant. This is accomplished by the introduction of several high energy implants. First the buried la...