Mo—In—Mn metallization is used to form ohmic contact on Be—implanted Rapid Thermally annealed GaAs. The rapid thermal alloying of Mo—In—Mn contact metallization is performed at various temperatures and times in A.G. Associates Heat Pulse 410 system in forming gas atmosphere. The electrical properties of the contacts were analyzed by current-voltage and contact resistivity measurements. The microstructures of the contacts were analyzed using scanning electron microscope, energy dispersive x-ray analysis, x-ray diffraction and secondary ion mass spectroscopy.

We have observed for the first time reversible changes in the sheet carrier concentration of the rapid thermally annealed Se and Zn implanted GaAs samples during subsequent heat treatments. The electrical profiles of the implanted samples have also been modified during the annealing processes. By observing the initial rate of change in the carrier concentration, an activation energy of about 2 eV is obtained which is thought to correspond to the diffusion of gallium atoms/vacancies.

The Greater Silicon Valley Implant Users' Group (GSVIUG) has conducted a round robin to determine the uniformity and repeatability available in wafers processed with modern RTP equipment. High-dose ion implantation (As, 5E15, 80keV) of 150mm wafers was used to monitor temperature distribution through sheet resistance. Sheet resistance maps were then used to compare the uniformity and repeatability of each vendor. As previously reported, the actual uniformity results varied significantly with RTP vendor and implant conditions, ranging from 0.77% (one sigma/mean) to 3.55%. In addition, some contour patterns were quite representative of specific vendors.

Subsequently, wafers from each participating vendor were evaluated by three techniques in order to determine what damage or defects might have resulted from the RTP process: laser flatness measurement, optical-imaging inspection, and thermal wave measurement. The flatness measurement system was used to measure the warpage of each sample. The reflective-optical inspection technique is a full-field, non-destructive technique that provides a real-time visual display, evidenced by light and dark field contrast over the entire wafer. The thermal wave measurement system uses two laser probes to measure a difference in modulated reflectance which results from damage or defects within the wafer.

This paper describes each of the three techniques and summarizes the measured results of wafer defects and damage due to the processing by various RTP vendors. Comparisons between the three measurement techniques are made.

The emissivity effects and compensation schemes encountered in pyrometric temperature measurements in RTP systems are described in this paper. The emissivity effects include substrate roughness, layered films, substrate temperature, and chamber reflectivity. Compensation techniques are derived based on the emissivity effects, and include reference thermocouples and reflectance-based measurements. Compensated emissivity results in wafer-to-wafer temperature variations of less than ± 6 C, compared to as much as ± 100 C for uncompensated emissivity. A new model for emissivity analysis at temperatures larger than 700 C is also described.

Rapid thermal processing technology is being investigated for many uses such as shallow junction diffusion and implant annealing. Most of these processes are done at temperatures above 700 C. It is desirable to use the rapid thermal processor for some low temperature applications such as hillock reduction because of the systems ability to heat up and cool down almost instantaneously as compared to conventional furnaces. Machine control for low temperature processing is more difficult than high temperature processing dur to the optical pyrometers inability to perform at its lower limit. Well documented nonlinear effects of wafer backside emissivity over a temperature range of 400C to 600C will also contribute to wafer to wafer temperature instability. In order to fully utilize the advantages of rapid thermal processing technology, it is imperative that the RTPs performance and repeatability at low temperatures be understood.

This paper will discuss the effect of wafer to wafer backside emissivity differences on wafer temperature for low temperature applications. Typical wafer to wafer backside emissivity variation is presented as well as the measurement error of the Peak “ACE” system. “ACE” (Automatic Compensation for Emissivity) can be used to correct for emissivity differences from wafer to wafer.

Effect of improper emissivity selection on actual wafer temperature is presented. Also actual wafer temperature sensitivity to changes in programmed temperature with constant, uncompensated emissivity is demonstrated.

Lamp current monitoring is discussed with supporting data to show the ability of it to be used as a day to day monitor of system performance. Also, The effects of lamp problems associated with idle current.

A complete theory of wafer heating during rapid thermal processing (RTP) is presented. Excellent agreement with experimental results of two commercial RTP systems is obtained. The temperature uniformity is limited by radiation loss at the wafer edge in the stationary state and by nonuniform illumination of the wafer during ramp-up. Structures on wafers are also potential sources for nonuniform heating. Considerable dynamic temperature inhomogeneities during rap-up might limitfu ture applications of RTPe specially when wafer sizes become larger. Possible improvements are suggested regarding adequate process cycling, chip and equipment design.

In the search of a high quality thin inter-polysilicon dielectric which has high breakdown voltage and low leakage current for high density non-volatile memory applications, thin (150±) inter-polysilicon reoxidized nitrided oxide capacitors were fabricated with multiple rapid thermal processing. While rapid thermal nitridation degraded the breakdown field if compared to the rapid thermal oxide capacitors, rapid thermal reoxidation greatly enhanced the dielectric strength of the rapid thermal nitrided samples. The short reoxidations increased the film thickness by less than 10 \. Breakdown field of optimized inter-polysilicon RTO/RTN/RTO capacitors up to 14 MV/cm has been measured.