Influence of optical properties of the SOI structure on the wafer temperature during rapid thermal annealing

Abstract

Optical characteristics are compared theoretically, and temperature differences of the Si wafer with the B doped SOI structure and substrate wafer are evaluated during rapid thermal annealing. It is shown that under identical annealing conditions and temperatures above 800 K, the difference in their temperatures can reach ~30 K. We studied the dependence of the total emissivity and temperature of the wafer with the SOI structure on the concentration of the doping impurity in the Si layer. The method of the quantitative analysis of variations of the wafer temperature under invariable annealing conditions depending on the variations of emissivity of its surfaces is suggested.

Temperature-dependent Si29 incorporation during deposition of highly enriched Si28 films

“…The emissivity as measured through the chamber window changes from about 0.25 at 363 °C up to 0.42 at 577 °C and is expected to reach a high value of 0.68 within the range of temperatures used in this study. This range of values is similar to emissivity values for Si surfaces reported in the literature (≈ 0.1 at 100 °C and 0.68 at > 800 °C) 25 . Including uncertainties in the calibration, the pyrometer temperature readings of the substrate are estimated to have a 5 % relative uncertainty due to fluctuations in the current used for sample heating as well as temperature gradients across the sample.…”

Temperature bistability in a silicon wafer with a doped layer on lamp-based heating

“…Doped-layer-related correction to the wafer temperature for a silicon wafer on heat treatment in a lamp-heated reactor As shown in the above calculations and previous theoretical studies [19][20][21][22], doped layers fabricated in the surface region of a silicon wafer or film structures grown at the surface change the emissivity of the wafer. The change in the emissivity yields a change in the wafer temperature compared to the substrate temperature under the same conditions of heat treatment in thermal reactors of RTP setups.…”

“…From formula (19), it follows that, in the system with pure radiation heat transfer, the temperature difference between the wafer with a doped layer or a film and the substrate is unambiguously determined by the balance between the layer-or film-induced changes in the emissivities of the wafer face and back surfaces [21].…”

“…Consideration for the deviation caused by implantation of dopants into the surface region of a silicon wafer or into a thin silicon layer in silicon-on-insulator (SOI) structures makes it possible to properly improve the conditions of annealing and, thus, to prevent the undesirable spreading of the concentration profiles of incorporated dopant atoms. The influence of the boron concentration implanted into the silicon layer of a SOI structure upon the implantationinduced deviation of the wafer temperature from the boron-free structure temperature was studied theoretically [21]. In calculations carried out in [21], the heat model of the thermal reactor with an BB heater and an BB absorber was similar to the model used in this study, except that the possibility of supplementary heat removal by the convective or conductive mechanisms and, hence, the possibility of temperature bistability in the wafer were disregarded.…”

“…The influence of the boron concentration implanted into the silicon layer of a SOI structure upon the implantationinduced deviation of the wafer temperature from the boron-free structure temperature was studied theoretically [21]. In calculations carried out in [21], the heat model of the thermal reactor with an BB heater and an BB absorber was similar to the model used in this study, except that the possibility of supplementary heat removal by the convective or conductive mechanisms and, hence, the possibility of temperature bistability in the wafer were disregarded. In the case considered in [21], the correction to the wafer temperature, ΔT w , defined by the changes in the integrated emissivities of the wafer input and output surfaces, Δε in and Δε out , for the substrate with the emissivity ε w can be calculated by the formula…”