Schematic of the in situ curvature measurement setup. The wafer is mounted on a graphite wafer holder called “satellite.”
Measured curvature change during heat-up due to bowing of the substrate caused by the temperature gradient between heated wafer back side and cooled wafer front side. The samples S3 and S4 are described in Table I .
Comparison of room temperature curvature for sample S1 with lattice plane bow measured ex situ by XRD and surface bow in situ by laser deflectometry.
Measured (symbols) XRD scans for samples S1 (Al0.4Ga0.6As) (a) and S3 (Al0.89Ga0.11As) (b) measured at different temperatures. The solid curves represent simulated scans at RT.
In situ curvature transients of samples S1, S2 (Al0.4Ga0.6As) (a) and S3, S4 (Al0.89Ga0.11As).
Extracted curvature values from Fig. 6 plotted against wafer temperature for samples S1, S2 (a) and S3, S4 (b) (Note: lines were added as guide for the eyes only).
Comparison of the values for the thermal expansion coefficient obtained in this work with values from literature.
Overview of sample parameters.
Comparison of the obtained values for thermal expansion coefficients from ex situ T-XRD, change of curvature with layer thickness and change of curvature with temperature.
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