Benchmarking of temperature measurement and control capability of commercially available rapid thermal processor (RTP) systems

Abstract

Rapid Thermal Processors (RTP) have been used in the semiconductor industry mainly for silicidation and implant anneal with limited success. RTP has been projected as a potential tool for years to be used for high temperature processes such as oxidation, junction annealing especially with low thermal budgets. The main handicap of these systems is the difficulty in measuring and controlling the temperature to the required specification. SEMATECH is in the process of establishing a joint development project (JDP) with supplier community to improve the situation. To understand the capability of the tools, a benchmark experiment was conducted using oxidation at 1 100°C (target 90 A), and Boron implant (5E 15 @ 20 KeV) anneal at 900°C for 20 sec. Oxide thickness and sheet resistance were measured as an indirect capability of temperature measurement and control of the tools. The experiments in RTP were performed with 'pyrometer closed-loop control' and 'open-loop power control' where applicable. Both process data and temperature measurement data are analyzed and presented. The wafers used for this experiment were 200 mm size, with varied backside films. The analysis of oxide thickness and sheet resistance (implant anneal) data shows that the closed-loop pyrometer control of temperature is not a viable technique to use in the manufacturing. The power control technique with the pyrometer in the open-loop (read only) demonstrates better process control and can be used until more viable technique is found. The reproducibility of open-loop power control technique for longer periods needs to be evaluated. This study demonstrates the urgent need to develop a real time temperature measurement and control technique for the RTP tools to be accepted in the manufacturing world.