Diffusion phenomena at the interface between dielectric films and compound semiconductors

Abstract

The diffusion phenomena at the interface between dielectric films and compound semiconductors under two kinds of condition (humid or dry thermal) have been studied by means of secondary ion mass spectrometry (SIMS). Under the humid condition -the pressure cooker test at 121• C, 100% relative humidity and 2 atm -we confirmed that oxygen diffused into dielectric films of SiN x or SiO x N y from the surface and that both Ga and As diffused into films from GaAs substrates simultaneously. Because such diffusion phenomena did not occur under the dry thermal condition at 120 • C, the diffusion was assumed to be influenced by the existence of water vapour. In addition, we investigated the selective diffusion of Ga from AlGaAs into SiO x under the dry thermal condition with rapid thermal annealing. We found that the diffusion velocities depended on the SiO x growing method and the diffusion into SiO x deposited by sputtering was more remarkable than that by plasma chemical vapour deposition

Interface Between Atomic Layer Deposition Ta2O5 Films and GaAs(100) Surfaces

“…As a result we have to assume that such diffusion processes occur through 2–4 nm thick Ta 2 O 5 films. Diffusion of species through solid films several nanometers thick has been reported in a number of studies: A small sample includes the following examples: In the deposition of manganese on Si, diffusion of species through the film is used to explain the experimental observations; , Si diffusion through La 2 O 3 films spanning several tens of nanometers as well as diffusion of O, Ga, and As through SiN x and SiO x N y on GaAs have been observed; The high- k literature is full of examples on interfacial oxidation when several nanometer thick stacks on Si are annealed in the presence even of low O 2 concentrations. − …”

Characteristics of SiN/GaAs interface under exposure to high-temperature and high-humidity conditions measured by photoreflectance spectroscopy

“…Because these dissociated species have a smaller molecular radius than the larger H 2 O molecules, they can easily diffuse into the SiN film and reach the SiN/GaAs interface. This phenomenon can be estimated from the SIMS data [5]. The SIMS result shows that although the reaction at the SiN/GaAs interface begins, oxidation is observed only at the SiN surface; this implies that small species diffuse more rapidly in the SiN film.…”

“…Hisaka et al reported that the maximum drain current (I D(MAX) ) of AlGaAs/InGaAs pseudomorphic high electron mobility transistor (PHEMT) devices decreased when these devices were exposed to high-temperature and high-humidity with electrical bias condition [4]. Shiramizu et al exposed a planar SiN/GaAs sample and observed that oxygen diffused from the surface of the sample; they identified the reaction that occurred between GaAs and moisture using secondary-ion mass spectrometry (SIMS) [5]. This pa-per describes the electrical characteristics of the SiN/GaAs interface after it is exposed to high-temperature and high-humidity.…”

Degradation mechanisms of GaAs PHEMTs in high humidity conditions

“…The diffusion phenomena of Ga and As at the interface between dielectric films and GaAs under humidity conditions has been studied by means of secondary ion mass spectrometry (SIMS) [7]. We also used SIMS to investigate the diffusion phenomena at the interface between the AlGaAs recess surface and the passivation film of samples especially fabricated with a large recess region (50 m · 70 lm).…”