The effects of rapid thermal processing (RTP) on the electrical properties of thin gate oxides in MOS devices have been studied. MOS capacitors have been analyzed by capacitance-voltage (C-V), current-voltage (I-V), and constant current stress techniques. MOSFET degradation due to hot carrier injection has also been investigated. No significant RTP-induced degradation was detected in any category of the device properties considered here. An abnormal trapping behavior was observed on the wafer annealed at 1100°C for 5 seconds.

Undoped polycrystalline silicon (poly-Si) films obtained by low pressure chemical vapour deposition (LPCVD) techniques have previously been demonstrated to align epitaxially with respect to the underlying (100) silicon substrate in the 1000-1100°C temperature regime. However the alignment rate at temperatures in excess of 1100°C is too rapid to be obtained by conventional furnace processing. Rapid Thermal Processing (RTP) offers an excellent technique of attaining this temperature in the requisite time and in this paper we report on the results of a study in which RTP has been used. Our results show an activation energy of ∼4.5eV, and that the growth rate constant is dramatically enhanced, without any alignment delay in the initial heat treatment phase, which is contrary to previous findings.

The very shallow junction of boron has been formed by the irradiation of ArF excimer laser on silicon substrate set in BF3 ambient. The sheet resistance decreases with the increase of the number of pulses and saturates above 150 pulses. It also decreases with increasing both gas pressure and laser energy density. The junction depth increases with increasing the number of pulses, ranging from about 400 Å to 2000 Å. It is confirmed from SIMS and four-point probe measurements that boron atoms diffused are electrically activated up to the concentration of about 1020cm−3.

A discourse is presented on the diverse manners and extent to which high-pressure reactors are being utilized in the semiconductor industry and their potential employment in research and development for ULSI fabrication. Various versions of high-pressure reactors are described. The major advantages of high-pressure techniques stem mainly from the ability to use lower processing temperatures which leads to reduced impurity diffusion, less wafer warpaqe, and fewer substrate defects. The exploitation of these benefits in LOCOS and FIPOS technologies for silicon IC device isolation is demonstrated. High-pressure steam has also been used to induce low-temperature reflow of PSG and BPSG before metallization. The applications and limitations of this technology are critically reviewed. Other application areas of high-pressure technigues being investigated extensively by R&D workers are discussed. These include the formation of reliable thin dielectrics in high-pressure ambients of oxygen, steam, nitrogen and ammonia, as well as the improvement of device reliability by using high pressure forming gas (H2/N2) in post-metallization annealing of radiation damage. Enhanced capabilities required for a conventional high-pressure reactor to achieve these applications are discussed. The review is complemented with data which reveal a rapidly growing utilization of high-pressure reactors for production as well as a steady growth in the number of potential applications for high-pressure techniques.

Laser induced flow of phosphosilicate glass, where the glass is a member of a multi-layer structure, was modeled with a one-dimensional coupled set of heat conduction and generation equations; the conventional approach was modified for explicit inclusion of non-ideal interfacial regions. There were no restrictions on the number or nature of material layers. Modeled behavior for 0.7 μm or 1 μm thick glass covering Al, or Si02, or Si agreed with observation; aluminum fusion accompanied by minimal glass flow when the AZ layer was covered by 0.7 μm glass was predicted and observed for the experimental laser pulse, as an example. Analysis also exposed the characteristics for successful laser generated glass flow; a rectangular pulse shape will permit the greatest control over the laser induced flow as well as provide the largest window for producing the desired flow while minimizing the effect on other material regions. Finally, experimental results with CW laser induced flow support the conclusion that the modeling successfully bridges four orders of magnitude in the thermal flux regime.

Thin films of amorphous SixNl-x alloys were produced by nitrogen ion beam assisted deposition of electron beam evaporated silicon. Infrared reflection spectra were measured in the range 600 to 10000 cm−1. Fringes were observed due to interference between light multiply-reflected from the front surface and film-substrate (single crystal silicon) interface. Similar measurements were performed on films crystallized by post-deposition furnace anneals. Analyses of the reflection spectra were used to obtain refractive index profiles. Profiles were correlated with nitrogen content as measured by Rutherford BackscatterLng Spectometry (RBS) and Auger Electron Spectroscopy (AES). Film adhesion, density, and purity were found to be improved for depositions assisted by nitrogen ion beams (1000 to 25,000 eV) relative to unassisted evaporation, and the index of refraction decreases monotonically with increasing nitrogen content.

In this paper, we present preliminary electrical characteristics of as-grown and NH3-nitrided thin gate and polysilicon oxides. Material characteristics are discussed in terms of ammonia concentration and nitridation temperature and pressure. Dielectric thicknesses obtained by ellipsometry, by Auger analysis and by capacitance-voltage measurements are compared. Electrical breakdown statistics for 10 atm and 1 atm pressure nitrided oxides are compared to as-grown thermal oxides.

Various pre-gate oxide cleaning and gettering techniques on the integrity of thin gate oxide were investigated. A 100 Å thick oxide capacitor was used to study its time-dependent breakdown characteristics and minority carrier lifetime. It has been shown that the oxide integrity as measured by time-dependent breakdown and the minority carrier lifetime are very sensitive to the cleaning technique. On the other hand, given adequate cleaning process, different intrinsic gettering schemes may only influence the oxygen precipitation, as well as the minority carrier lifetime, but not the oxide integrity.

The growth of high quality 100 Å thermal oxide is investigated. Different growth conditions including oxidation temperature, oxidation rate, and gas ambient are explored and they all produce good oxides. However, it will be demonstrated that the best oxide with defect density as low as 0.2cm−2, breakdown field ≃ 12 MV/cm and good reproducibility is grown with low temperature (800°C) low rate oxidation in dry oxygen. The midgap interface trap density of this oxide is ∼ 2.0 × 1010eV−1cm−2 obtained from high-frequency and quasi-static C-V data. A model based on physical mechanisms controlling the kinetics of thin oxide growth is developed to understand how the quality of thin oxide is affected by growth conditions and to explain why the low temperature oxidation in dry oxygen yields the best film.

A scaled-down MOS transistor requires high-quality thin gate oxide (∼100 Å) as in tunnel oxide for an EEPROM device. Instead of investigating the lower (SiO2/Si) interface properties, we study the upper (poly-Si/SiO2) interface as affected by poly deposition conditions, phosphorus doping, and thermal cycling. The results show that prolonged or high-temperature heat treatment will degrade thin oxide quality. The initial V-t slope derived from constant-current stressing data is used to assess oxide quality.

Current trends are in the direction of submicron MOSFETs employing gate dielectrics in the thickness range of about 30 - 100A°. The performance and reliability of submicron MOSFETs can be improved by using high dielectric constant gate dielectric material. A new concept involving 2 or more dielectric material is proposed in this paper. In- situ rapid isothermal processing is proposed for the fabrication of thin gate dielectrics.

A two-dimensional model for simulating the growth of SiO2in a porous Si layer is described. The model makes use of rapid early oxidation based on the presence of micropores in the oxide normal to the growing oxide-oxidant inter- face. With initial pore shape, ambient pressure and oxidation temperature as inputs, the model predicts the final morphology of the grown oxide film and calculates the refractive index and other key indicators of oxide quality. The model is a first step towards allowing the design of optimized processes for formation of high-integrity oxidized porous Si layers.