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Browse Prior Art Database

DIFFUSED ATOMIC BONDED WAFER

IP.com Disclosure Number: IPCOM000007042D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-20
Document File: 2 page(s) / 122K

Publishing Venue

Motorola

Related People

Jose Ramirez: AUTHOR [+2]

Abstract

A new process that offers lower wafer cost with no crystallographic defects, improved thickness and resistivity uniformity within the wafer for tighter device electrical parametric distributions with simi- lar RBSOA capabilities is the "Diffused Atomic Bonded Wafer? Figure #l shows a cross section of a Diffused Atomic Bonded wafer.

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MO7VROLA INC. Technical Developments Volume 20 October 1993

DIFFUSED ATOMIC BONDED WAFER

by Jose Ramirez and Min Zou

  A new process that offers lower wafer cost with no crystallographic defects, improved thickness and resistivity uniformity within the wafer for tighter device electrical parametric distributions with simi- lar RBSOA capabilities is the "Diffused Atomic

Bonded Wafer? Figure #l shows a cross section of a Diffused Atomic Bonded wafer.

  The Direct Bonding or Atomic Bonding process is a well known technique used in the semiconduc- tor industry, Motorola's NPN high voltage Power Transistors greater than 1500 volts which are nor- mally built using wafers with a single thick Epi layer of high resistivity (-150 pm/100 Q-cm) had been successmlly built using the Atomic Bonding tech- nique since 1991 by Direct or Atomic Bonding a CZ substrate (c 0.020 O-cm) to a FZ wafer (80-150 Q-cm).

  Device Simulation was done to verify the effect on electrical performance of various difised energy layers profiles against the epi energy layer, in gen- eral all the DC characteristics didn't change much as long as the energy layer depth was kept at 25 microns, however, some effect on the RBSOA per- formance was noticed.

  The peak hFE as well as the high current hFE distribution of the Atomic Diffused wafer were similar to the Epi wafer, the breakdown voltage also was similar. Device Simulation had predicted that if Collector width (WC) is fixed, there won't be any significant changes on current gain and breakdown distributions despite changing the slope and thick- ness of the energy layer.

  The Vcb(f) distribution was as low as the Epi indicating a "void free" interface between the FZ wafer and the CZ substrate, a poor wafer bonding would had greatly affected Vcb(t) and consequently Vce(sat) and high current hFE. The bonded wafers exhibited lower minority carrier Lifetime, this may be due to the interface between the FZ wafer and the CZ substrate.

  Assembled units were submitted to Forward Bias Operating Area (FBSOA) and Reverse Bias Operat- ing Area (RBSOA), the Atomic Bonded wafers performed as good as the Epi wafers on FBSOA indi- cating a good bonding, the RBSOA performance of the Atomic Bonded Wafer was within device speci- fication but slightly lower than the Epi product, this was caused by the profile of...