Jan 20, 2020

Hydrogen Implantation in Germanium

Hydrogen implantation of germanium is a promising technique for layer transfer. However, both the implantation process, and subsequent heat treatment can create defects in the transferred layer, which detrimentally effect the performance of devices fabricated on these transferred layers. In this study, implanted Germanium wafers were given various anneals and analysed optically and by spreading resistance, to gain insight on the nature of such defects. GeOI layers were produced by thermal splitting of implanted germanium wafers bonded to sapphire handle substrates.

Source:IOPscience

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Jan 13, 2020

The Study on Defects of Germanium-on-Insulator Fabricated by a Low Temperature Smart-Cut Process

Germanium-on-insulator (GeOI) was manufactured by a low temperature Smart-cut process. The blistering of H-implanted Ge wafer was first studied and the kinetics of blistering onset (time) as a function of annealing temperature was described to determine the subsequent splitting. Germanium layer transfer was achieved by a 2700C annealing after the atomic level Ge/SiO2 wafer bonding was formed by a 1500C annealing. The defects on the transferred Ge layer were mitigated thanks to the extended annealing and mainly distributed at the rim of GeOI wafer.

Source:IOPscience

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Jan 7, 2020

Gaseous Diffusion of Arsenic and Phosphorus into Germanium

Presence of germanium arsenide was found at the germanium surface, particularly at arsenic surface concentrations exceeding 1019 at./cc, using electron diffraction techniques. Thermal conversion of the interior of the germanium wafers (which were 15 ohm‐cm N‐type) to P‐type could be suppressed by arsenic surface concentrations exceeding 5.1018 at./cc. This elimination of thermal conversion depends on the surface to volume ratio of the wafer. It is proposed that the thermal conversion level in the bulk of the indiffused material depends on the electric field which arises during diffusion if the impurity concentration exceeds the intrinsic carrier concentration.

Source:IOPscience
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Jan 2, 2020

Germanium Back‐Side Gettering of Gold in Silicon

A novel back‐side gettering technique was developed. The technique consists of applying germanium to the back side of a silicon wafer and then annealing in either a nitrogen or an oxygen ambient. The concentration profiles for gold before and after anneals were established to better than the part per million (ppm) level by using atomic absorption spectroscopy. The minority carrier lifetime of control and gettered samples was determined. The technique was found to be effective for the removal of gold from the active device region of a silicon wafer. The difference in activity coefficients for gold in silicon and gold in germanium is the theoretical basis for the gettering of gold from the silicon to the germanium on the back side. In addition to gettering gold from the front surface of the wafer, comparison was made of a germanium‐gettered wafer with a control wafer, showing that the application of germanium to the back side of a silicon wafer, followed by thermal annealing, is effective in preventing the formation of oxidation‐induced stacking faults (OISF) during high temperature oxidation.

Source:IOPscience
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