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A NOVEL FURNACE CANTILEVER SYSTEM FOR SHALLOW JUNCTION DIFFUSION PROCESSES

IP.com Disclosure Number: IPCOM000007329D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-15
Document File: 1 page(s) / 76K

Publishing Venue

Motorola

Related People

Stephen E. Garling: AUTHOR [+2]

Abstract

Modern bipolar integrated circuits have demand- ing junction profile requirements. Device designs that have 0.3 pm base-collector junction depths and 0.1 micron emitter-base junction depths require careful control of thermal cycles during processing. For the emitter anneal application, a novel diffusion canti- lever system has been designed that maintains shal- low junctions with sharp junction interface profiles.

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MOTOROLA Technical Developments Volume 24

March 1995

A NOVEL FURNACE CANTILEVER SYSTEM FOR SHALLOW JUNCTION DIFFUSION PROCESSES

by Stephen E. Garling and Victoria Vonts

  Modern bipolar integrated circuits have demand- ing junction profile requirements. Device designs that have 0.3 pm base-collector junction depths and 0.1 micron emitter-base junction depths require careful control of thermal cycles during processing. For the emitter anneal application, a novel diffusion canti- lever system has been designed that maintains shal- low junctions with sharp junction interface profiles.

  Process modeling and development required that the emitter anneal process step be a thermal "spike" of95O"C for 30 minutes, with no temperature ramps. In order to prevent wafer warpage, the wafers are set horizontally on a quartz lattice, which enables rapid but uniform heat transfer to and from the wafers. To provide sufficient process capacity, multiple lev- els of quartz lattices are utilitized. Significant heat transfer differences exist between levels of a multi- ple stack lattice system. On the top lattice, the wafers are exposed to significant radiation heating. On the bottom lattice, the wafers are subject to increased cooling being in close proximity to the standard heavy, thermally massive Sic cantilever paddle. In order to minimize process temperature variation at emitter anneal, a novel cantilever was designed to address the radiation heating and paddle cooling effects (see Figure below).

To eliminate the radiation heating effect, a radi- ation barrier was...