Jean-Claude Muller

Laser‐induced diffusion by irradiation of silicon dipped into an organic solution of the dopant

A new method for preparation of p‐n junctions is presented. It consists in dipping the silicon to be doped into an organic liquid containing the dopant and irradiating its surface through the liquid with a high‐energy pulsed ruby laser. It is shown that by this treatment the dopant is driven into the crystal and that abrupt junctions with high doping levels can be realized. Using this simple technique, solar cells with AM1 efficiencies above 13% can be prepared.

Laser processing in the preparation of silicon solar cells

Besides cheaper techniques of growing the starting silicon, the reduction of manufacturing costs of terrestrial solar cells needs new automated approaches for the preparation of the junction. The possibilities given by laser processing are considered for three different structures: diffused junctions, ion implanted and alloyed diodes prepared from layers of dopants just deposited on surface.

Defect generation and gettering during rapid thermal processing

The authors present results showing that deep-level transient spectroscopy (DLTS) is particularly efficient in identifying the origin of rapid thermal processing (RTP) related defects. It was found that defects are mostly related to residual impurities present in the as-grown silicon wafers or unintentionally introduced during high-temperature processing steps. It was shown, in particular, that these impurities can be thermally annealed out or neutralized by a hydrogenation process. In addition, the authors demonstrated that these impurities can be swept out of the active region of the device by a gettering effect during the RTP which is similar to that occurring in a classical thermal treatment. >

Electrical effects of surface and deep states induced in n‐type silicon by rapid thermal processing

Induced defects in Czochralski‐grown n‐type 〈111〉 1–5 Ω cm silicon wafers due to high‐temperature (800u2009°C/10 s; cooling rate≂100u2009°C/s) rapid thermal annealing (RTA) have been studied using deep level transient spectroscopy. The samples processed at 1000u2009°C and above showed a defect continuum containing at least an electron trap at E(0.58 eV) with a concentration ≂1015 cm−3. The electrical activity of the defects substantially degraded the current/voltage and capacitance/voltage characteristics of the Schottky diodes made from the processed samples with a barrier height reduction from 0.85 V at 800u2009°C/900u2009°C to 0.32 V at 1100u2009°C. However, a further RTA treatment at 650u2009°C for 60 s resulted in a complete restoration of these characteristics and no trap was recorded in the deep level transient spectroscopy spectrum. This degradation, which was not observed in oxide‐encapsulated samples processed in the same temperature range, is considered to be due to impurity contamination during RTA processing which is en...

Activation and gettering of intrinsic metallic impurities during rapid thermal processing

Abstract We show in this study that deep-level transient spectroscopy is an effective means of revealing residual metallic impurities in commercial silicon which are electrically activated by rapid thermal processing (RTP). In particular we demonstrate that the dominant activated metallic impurity, detected after RTP (at temperatures of 800 and 1000°C for 10s) and serial sectioning from the front side or the back side of the samples, has an inhomogeneous distribution. This is characteristic for a getter effect and is similar to that observed for intentionally gold-doped samples followed by RTP. Serial sectioning in steps of about 25 μm allows us to establish a complete picture of what happens during RTP: activation and gettering of residual bulk impurities, as well as the activation of surface contaminants which have been introduced by the high temperature treatment.

Rapid Thermal Annealing of Spin-On Glass Films

Rapid thermal annealing is investigated for curing spin-on glass insulating films. The annealed SOG films were mainly evaluated using infrared absorption spectroscopy and by electrical measurement of the defects present at the Si/Sio 2 interface. We found in particular after rapid thermal annealing an important densification of the layers as a function of temperature and a reduction of the interfacial state densities which are comparable to classical thermal oxides.

Thermal annealing of excimer-laser-induced defects in virgin silicon

Abstract The advantages of pulsed excimer lasers for semiconductor processing are now well established. The major obstacle to extensive application of these lasers is the presence of electrically active point defects in the laser-annealed region. In this paper, deep level transient spectroscopy measurements have been used to detect traps in both n- and p-type virgin silicon irradiated by an ArF excimer laser (0.19 μm) working in the liquid phase regime. These defects have been compared with those reported for other solid state lasers (ruby, YAG). The annealing kinetics of the dominant defects have been studied within the temperature range 400–650°C using rapid and conventional thermal processing.

Rapid Thermal Process-Induced Defects : Gettering of Internal Contaminants

We show in this study that RTP-induced defects analysed by Deep Level Transient Spectroscopy (DLTS) are related to residual impurities present in as-grown silicon wafers. For one particular material an activation of a specific residual metallic impurity was observed in the temperature range 800 - 1000°C. This impurity can be returned to an electrically inactive precipitated form by classical thermal annealing (CTA) with a slow cooling rate or neutralized by means of low-energy hydrogen ion implantation.

Phosphorus Glass Doping of Polycrystalline Silicon During Rapid Thermal Annealing

We show that the use of phosphorus doped spin-on glasses as diffusion source is an attractive approach for the formation of shallow junctions in polycrystalline silicon materials. Moreover, this very simple doping process using a glass film can be fruitfully associated to rapid thermal annealing.

Rapid thermal processing induced defects and gettering effects in silicon

In recent years rapid thermal processes (RTPs) have been widely studied to replace conventional processing. The use of this technique which is less time and energy consumption than classical thermal treatments can be widespread if in one hand the origin of process induced defects can be clarified and in the other hand the gettering of impurities in silicon can be effective. Up to now the RTP introduced defects was inherently correlated to the quenching step due to the fast cooling rate (typically around 100C/s) and the time duration of the order of seconds to tens of seconds was generally considered to be inappropriate to increase by gettering the purity of materials in the active region. The reason involved was the time scale which would not allow the impurities to migrate to the gettering sites given the diffusity values observed and measured in conventional diffusion studies. In our study we will present results showing that Deep Level Transient Spectroscopy (DLTS) is particularly efficient to identify the origin of RTP related defects. We found that they are mostly related to residual impurities present in the as-grown silicon wafers or unintentionally introduced during high-temperature processing steps. For one particular material an activation of a specific residual metallic-impurity was observed in the temperature range 800-1000C. This impurity can be returned to an electrically inactive precipitated form by classical thermal annealing (CTA) with a slow