Silicon heating by a microwave-drill applicator with optical thermometry

Abstract

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 cm 2 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.

Deposition of Air-Stable Zinc Nanoparticles on Glass Slides by the Solvent-Assisted Deposition in Plasma (SADIP) Method

“…It is well-known that conducting materials (metals and ceramics) can be heated under the influence of microwave irradiation. It was found that Al reaches 577 °C after 6 min of microwave exposure, and Si wafer can be heated to the 450 °C within only 4 s using microwave irradiation of 350 W . Since in the current study a 900 W magnetron is used, it is reasonable to assume that the temperatures and the heating rates for Si wafer and Al foil are even larger.…”

Breakdown spectroscopy induced by localized microwaves for material identification

“…A heuristic condition for the microwave‐drill applicability can be phrased as W > D , where W is the localized microwave power absorbed in the hotspot, and D is a thermal factor given by $D_{\rm D} = 2.5k_{{\rm th}} \left( {{{d_{{\rm hs}} \Delta T} \mathord{\left/{\vphantom {{d_{{\rm hs}} \Delta T} {\Delta \varepsilon ''_{\rm r} }}} \right.\kern-\nulldelimiterspace} {\Delta \varepsilon ''_{\rm r} }}} \right)$ and $D_{\rm M} = 1.4k_{{\rm th}} \sqrt {\omega \mu _0 \sigma } \Delta Td_{{\rm hs}}^2 \,$ for dielectrics and conductors, respectively, where k th is the thermal conductivity, d hs is the hotspot diameter, ω is the microwave angular frequency, and Δ T and Δε′ r are the differences between the melting and the ambient temperatures and between the corresponding dielectric losses, respectively. This rough one‐dimensional model is valid for dielectric wafers [11] and metallic foils [13]. The condition W > D can be satisfied for most practical materials in reasonable microwave power levels, except for perfect dielectrics such as pure alumina or sapphire.…”

“…The microwave drill concentrates the microwave energy into a hotspot of ∼1‐mm diameter on the material surface by virtue of the localized thermal‐runaway effect [10]. The microwave‐drill type apparatus is used here only for the localized heating [11] without deepening the hole. The molten hotspot is further evaporated and ionized by the localized microwave field.…”

Observations of Ball-Lightning-Like Plasmoids Ejected from Silicon by Localized Microwaves

“…The experimental setup depicted in Figure 1 a,b consist of a microwave cavity made of a WR340 waveguide with additional openings (in microwave cutoff) for diagnostics, namely for the video imaging and optical spectroscopy line-of-sight, and for the synchrotron X-ray beam passing through the plasmoid (as in [ 1 , 13 , 14 , 15 ]). The substrate made of silicon is vertically positioned as in [ 19 ]. The movable electrode directs the microwave energy locally into the substrate.…”