Induction system for rapid heat treatment of semiconductor wafers

Abstract

A semiconductor wafer is transported by a mechanical system into or out of a quartz housing filled with a protection gas. The wafer is placed between and spaced apart from two graphite plates. A RF induction coil surrounding the quartz housing is used to heat the graphite plates. Radiation from the heated graphite plates heats the wafer from room temperature to an elevated desired temperature. During the time period when a wafer absorbs radiation primarily through electron-to-electron transition, heat convection and conduction by the protection gas conveys heat from the graphite plates to the wafer to accelerate the heating of the wafer and reduces temperature nonuniformity of the wafer. A reflector means in the form of a second smaller housing is placed inside the larger quartz housing; the second housing formed by the reflector means encloses the two graphite plates and the wafer except for an opening for delivering and withdrawing the wafer and for a hole in upper part of the housing for determining temperature of the water. The reflector means reflects radiation back towards the graphite to improve heating efficiency. The second housing formed by the reflector plate confines the heating of the protection gas to the portion inside the second housing, thereby improving the efficiency of the gas in transporting heat by convection and conduction. In such manner heating of the wafer to a given temperature is accelerated and the uniformity of wafer temperature during the heating is improved.