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Type: Artigo de evento
Title: Ecr-cvd Sinx Passivation In Gaas-based Devices
Author: Zoccal L.B.
Diniz J.A.
Ramos A.C.S.
Abstract: In this paper we have developed an excellent quality passivation silicon nitride film that requires no surface pre-treatment, is fully compatible to Monolithic Microwave Integrated Circuits (MMICs). The silicon nitride film is deposited (by Electron Cyclotron Resonance (ECR) - Chemical Vapor Deposition (CVD)) directly over GaAs-n substrate and over InGaP/GaAs heterojunction structures, which are used for Heterojunction Bipolar Transistors (HBTs). Optical emission spectrometry (OES) was used for plasma characterization, and low formation of H and NH molecules in the gas phase was detected at pressure of 2 mTorr. These molecules can degrade the III-V semiconductor surfaces due to the preferential loss of As or P and the hydrogen incorporation at substrate. The substrates were cleaned with organic solvents using a Sox-let distillate. The ECR depositions were carried out at a fixed substrate temperature of 20°C, SiH4/N2 flow ratio of l, Ar flow of 5 sccm, pressure of 2 mTorr and microwave (2.45 GHz) and RF (13.56 MHz) powers of 250 W and 4 W, respectively. Metal/nitride/GaAs-n capacitors were fabricated from all the samples considered with 285 mn thick AuGeNi gate and wafer backside electrodes, which were formed by e-beam evaporation, sintered by conventional furnace in forming gas (92%N2 + 8%H2) at 450°C for 3.5 minutes. The gate electrodes were patterned with a mask composed of an array of 200 μm diameter dots. C-V measurements at 1 MHz were performed. The effective charge densities Q0 of 3×1011 cm -2 were calculated directly from the flatband voltage shift V fb. Leakage current densities lower than 1 μA/cm2 (between -2 V to 2 V) are determined through I-V characterization. We have applied this film to our InGaP/GaAs HBT fabrication process with excellent results, such as higher current gain of passivated device in related to unpassivated HBTs.
Rights: fechado
Identifier DOI: 
Date Issue: 2005
Appears in Collections:Unicamp - Artigos e Outros Documentos

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