On the photon annealing of silicon-implanted gallium-nitride layers

The conditions for the formation of ion-doped layers in gallium nitride upon the incorporation of silicon ions followed by photon annealing in the presence of silicon dioxide and nitride coatings are analyzed. The conditions of the formation of ion-doped layers with a high degree of impurity activation are established. The temperature dependences of the surface concentration and mobility of charge carriers in ion-doped GaN layers annealed at different temperatures are studied.     

Silicon nitride, a new diffusion mask

Although in the last decade silicon dioxide has been used extensively as a diffusion mask in semiconductor device fabrication, it has many limitations. It fails to mask many important diffusants such as gallium, aluminum, zinc, and oxygen. The masking properties of silicon nitride have been investigated. The results show that silicon nitride masks not only the same diffusants as silicon dioxide but also many diffusants where silicon dioxide fails.     

Nitride chemical passivation of a GaAs (100) Surface: Effect on the electrical characteristics of Au/GaAs surface-barrier structures

The effect of chemical nitridation of GaAs substrates in a hydrazine-sulfide solution on the electrical characteristics of Au/GaAs Schottky structures has been studied. In nitridation of this kind, a solid passivating gallium nitride film with a monolayer thickness is formed on the surface of GaAs, providing almost direct contact between the semiconductor and the metal deposited on its surface. Au/GaAs structures fabricated on nitride substrates have ideality factors close to unity and are characterized by a narrow scatter of potential barrier heights. Prolonged heating of these structures at 350°C does not change these parameters. The data obtained show that the nitride monolayer formed on the GaAs surface upon treatment in hydrazidesulfide solutions effectively hinders atomic migration across the metal-semiconductor phase boundary.     

Asymmetrical current conduction across a 50 A Thick aluminium gallium nitride polarisation barrier

Rectification by a 50 Aring (5 nm) thick aluminium gallium nitride (AlGaN) polarisation barrier with maximum voltage swing of 27 V is demonstrated. In order to achieve a large voltage swing, the device is constructed with a 3000 Aring (300 nm) thick undoped gallium nitride (GaN) space charge layer adjacent to the barrier to enable a large voltage drop before the advent of impact ionisation breakdown. The spontaneous and piezoelectric polarisation discontinuities at the AlGaN/GaN interfaces determine the band profiles and the thermally assisted tunneling flux of electrons through the barrier. The 3.24 MV cm ^-1 electric field across the 50 Aring thick barrier at low bias enables efficient tunneling of electrons, despite the large effective electron mass of 0.19. The effective barrier seen by electrons changes from triangular to trapezoidal for one direction of bias and enhances the asymmetry effect. The demonstrated device characteristics show that wide band-gap polarisation barriers can potentially be used as the basic components of high-power microwave limiters     

氮化硅薄膜的等离子干法蚀刻

本文简述了干法腐蚀的现状、原理及其反应装置.给出了在圆筒型反应器中氮化硅薄膜的均匀刻蚀以及硅表面的平滑抛光的工艺条件,同时,也给出了在此工艺条件下,单晶硅、氮化硅、热生长二氧化硅、砷化镓以及光致抗蚀剂的腐蚀速率.对硅表面在高频场和等离子体轰击下表面性质的改变作了初步研究.并通过此工艺在制管中的成功应用,可看到它在降低成本,减少公害,以及进行微细加工方面所显示出来的优越性.目前,对实验结果和现象的分析尚处于定性的阶段.     

The application of polyimide/silicon nitride dual passivation to AlxGa1−xN/GaN high electron mobility transistors

PECVD silicon nitride passivation is quite frequently done at the end of AlGaN/GaN HEMT fabrication before substrate back-side lapping. However, the PECVD silicon nitride process is likely to produce pinholes in the passivation film. A very thick PECVD silicon nitride film may produce mechanical stress on the underlying device. Polyimide passivation has also been known to be effective for AlGaN/GaN HEMT and it can also serve as a stress buffer. However, polyimide can take up water while PECVD silicon nitride is a good diffusion barrier for water, etc. Thus it is expected that a dual PECVD silicon nitride/polyimide passivation will be a better choice than just a single layer of PECVD silicon nitride or polyimide. In this paper, we will demonstrate the application of a dual PECVD silicon nitride/polyimide passivation to AlGaN/GaN HEMT process.     

A polycide gate electrode with a conductive diffusion barrierformed with ECR nitrogen plasma for dual gate CMOS

A simple diffusion barrier technology for polycide gate electrodes is presented. An extremely thin silicon nitride layer is formed by poly Si surface nitridation with ECR nitrogen plasma of only nitrogen gas and without substrate heating. The silicon nitride layer acts as an excellent barrier to impurity diffusion from polysilicon to silicide. It was found that barrier formation with ECR nitrogen plasma results in no fatal degradation in the MOS interface characteristics. This technology is very effective for making dual polycide gates inexpensively due to its simplicity and a good affinity with conventional ULSI fabrication processes     

Hydrogen desorption and diffusion in PECVD silicon nitride. Application to passivation of CMOS active pixel sensors

Presented either as a source or as a barrier to hydrogen, plasma deposited silicon nitride can impact microelectronic device performances. The objective of this paper is to clarify the hydrogen behavior in silicon nitride in order to optimize film characteristics for each microelectronic application. A design of experiments methodology was used to statistically discriminate films properties which govern hydrogen diffusion and desorption from PECVD silicon nitride. Finally, we confirm, thanks to trials on CMOS active pixel sensor devices and dark current measurements, the role of the SiN passivation layer on Si remaining defect and we propose an optimized passivation stack.     

Cleaved Mirrors for Nitride Semiconductor Lasers

We demonstrate smooth cleaved gallium nitride facet mirrors on Si(111) substrates fabricated by a microcleaving technology. Cantilever features were defined by photolithography, followed by a vertical photo-enhanced electrochemical (PEC) etch until the substrate was exposed. Lateral undercuts underneath the cantilevers were created by a silicon isotropic wet etch, and the nitride cantilevers were isolated from the substrate completely. Mechanical forces were applied to break the cantilevers. The facets made by microcleaving showed improved roughness as confirmed by surface morphology characterization. The fabrication steps for microcleaved facets combined with laser processing on a full-wafer scale are proposed.     

Structural Characterization of Highly Conducting AlGaN (<Emphasis Type="Italic">x</Emphasis> > 50%) for Deep-Ultraviolet Light-Emitting Diode

Off-axis reciprocal-space mapping was performed on aluminum gallium nitride deep-ultraviolet light-emitting diode base layers. The results indicate that aluminum gallium nitride films growing on aluminum nitride-on-sapphire templates initially grow in compression, nearly lattice matched to the relaxed aluminum nitride buffer layer with approximately 0.5% biaxial strain. This compressive strain may be partially relieved over the course of the thick aluminum gallium nitride growth when a high-quality aluminum nitride and superlattice layer is used. Additionally, a growth interruption appears to allow growth of an unstrained aluminum gallium nitride layer without a gradual release of compressive strain. Growth on a bulk aluminum nitride substrate appears to yield an aluminum gallium nitride layer in tension rather than compression.