Silicon heating by a microwave-drill applicator with optical thermometry

This paper presents a method for heating silicon wafers locally by open-end coaxial microwave applicators, with optical techniques employed for measuring the temperature. Silicon samples of ∼2 × 2 cm² area were radiated in air atmosphere by a microwave drill operating at 2.45 GHz in the range of 20-450 W. The rate of temperature variation was measured by the Fabry-Pérot etalon effect in samples illuminated by InGaAs lasers. The steady-state temperatures were measured by the changes in the absorption index of an InGaAs laser beam. The experimental results indicate heating rates of ∼150 K s^-1 and a temperature range of 300-900 K across the silicon sample during the microwave heating process. Further operation of the microwave drill caused local melting of the silicon samples. This paper presents the experimental setup and results, as well as numerical simulations of the microwave heating process.