Trilayer lift-off metallization process using low temperature deposited SiN[sub x]

Journal Article · · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)

OSTI ID:6307957

Lothian, J R; Ren, F; Pearton, S J; Chakrabarti, U K; Abernathy, C R; Katz, A ^[1]

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1. AT T Bell Laboratories, Murray Hill, NJ (United States)

A trilevel resist scheme using low temperature (< 50[degrees]C) deposited SiN, rather than Ge for the transfer layer has been developed. This allows use of an optical stepper for lithographic patterning of the emitter-base junctions in GaAs/AlGaAs heterojunction bipolar transistors where a conventional lift-off process using a single level resist often leads to the presence of shorts between metallizations. The plasma-enhanced chemically vapor deposited (PECVD) SiN[sub x] shows a slightly larger degree of Si-H bonding compared to nitride deposited at higher temperature (275[degrees]C), and is under compressive stress ([approximately]5[times]10[sup 10] dyn cm[sup [minus]1]) which is considerably relieved upon thermal cycling to 500[degrees]C ([approximately]1.5[times]10[sup 10] dyn cm[sup [minus]2] after cooldown). This final stress is approximately a factor of 2 higher than conventional PECVD SiN[sub x] cycled in the same manner. The adhesion of the low temperature nitride to the underlying polydimethylglutarimide base layer in the trilevel resist is excellent, leading to high yields in the lift-off metallization process. These layers are etched in electron cyclotron resonance discharges of SF[sub 6] or O[sub 2], respectively, using low additional dc bias ([le] 100 V) on the sample. Subsequent deposition of the HBT base metallization (Ti/Ag/Au) and lift-off of the trilevel resist produces contacts with excellent edge definition and an absence of shorts between metallization. 14 refs., 7 figs.

• OSTI ID: 6307957
• Journal Information: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Vol. 10:6; ISSN 0734-211X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
JUNCTION TRANSISTORS
FABRICATION
SILICON NITRIDES
CHEMICAL VAPOR DEPOSITION
ADHESION
ELECTRON CYCLOTRON-RESONANCE
ETCHING
GALLIUM ARSENIDES
HETEROJUNCTIONS
INFRARED SPECTRA
LAYERS
TEMPERATURE DEPENDENCE
THERMAL CYCLING
ARSENIC COMPOUNDS
ARSENIDES
CHEMICAL COATING
CYCLOTRON RESONANCE
DEPOSITION
GALLIUM COMPOUNDS
JUNCTIONS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
RESONANCE
SEMICONDUCTOR DEVICES
SEMICONDUCTOR JUNCTIONS
SILICON COMPOUNDS
SPECTRA
SURFACE COATING
SURFACE FINISHING
TRANSISTORS
360601* - Other Materials- Preparation &amp; Manufacture
420200 - Engineering- Facilities
Equipment
&amp; Techniques