Shallow p+ diffusion into InGaAsP (λ=1.3 μm) has been improved by employing a new spin‐on source based on Zn‐doped alumina. Thereby the thermal expansion coefficients of diffusion source and semiconductor are better matched together than in case of the more common Zn‐doped silica films. Consequently, besides an excellent mechanical stability of the spin‐on films over a wide temperature range, the influence of mechanical stress on the diffusion process is effectively reduced. Applying diffusion temperatures around 600 °C surface hole concentrations above 6×1019 cm−3 and extremely low specific p‐contact resistances of 2–3×10−6 Ω cm2 have been achieved.

Improved shallow p+ diffusion into InGaAsP by a new spin‐on diffusion source

A new concentration profile is proposed to reduce the surface electric field without increasing the peak bulk electric field in p+-n-n+ structures. The field configuration in the structure is analysed using a computer which shows that by suitably adjusting the impurity concentration near the edges, the surface electric field can be made equal to the bulk field even in the presence of the surface charges. This results in a near ideal reverse breakdown voltage. Thus, a simple diamond scribing and breaking or chemical etching method can be used to process the diffused wafers.

Concentration profiling for high voltage p+-n-n+ diodes

A unified analytic approximation for high-concentration arsenic and boron diffusion profiles is presented. The unified profile is represented by a quadratic expression with coefficients determined by the impurity concentration near the surface and the total number of diffused impurities. The junction depth, the total number of impurities, and the sheet resistance calculated by this unified approximate profile are very close to recent results. Application of this approximate expression to the profile estimation of high-concentration phosphorus diffusion in silicon is also presented.

Profile estimation of high-concentration arsenic or boron diffusion in silicon

Preparation, characterization and application of RF sputter deposited boron doped silicon dioxide thin films

Diffusion of boron into silicon from doped oxide source

‘Spin-on’ sources are commercially available either under brand names like ‘Accuspin’ or doped silicate films manufactured by various companies. However, the method of preparation of these doping solutions is not known and since almost all these solutions become jelly after a certain duration during which the viscosity changes, it is preferable to prepare one's own solution so that one can easily control the solution composition to a particular requirement and achieve reproducibility. In this paper, we report easy-to-prepare ‘spin-on’ solutions for boron and arsenic which give highly reproducible surface concentrations very close to the solid solubility limit. These solutions are useful for deep junction formation in silicon.

V. P. Sundar Singh

Papers

Spin-on sources for boron and arsenic diffusion

A planar p-n junction with near ideal breakdown voltage

Atom-Chip for Direct Magnetic Trapping of Atoms from U-Magneto-Optical Trap