We have used x-ray diffraction to measure the strain perpendicular to thesubstrate surface in laser crystallized silicon films on oxidized siliconand fused quartz substrates. The dependence of the strain ongrainorientation was determined and the influence of the scan speed, theinsulating oxide thickness, and subsequent high temperature exposure wasexamined. Maximum strain was obtained for grains oriented with the (100)plane parallel to the substrate surface. The strain decreased withincreasing angle between the surface plane and the (100) plane of thegrains. The stress parallel to the surface in the variously oriented grainswas calculated from the stiffness tensor, assuming an isotropic, in-planestress, and a variation similar to the strain was found. The strain found onoxidized wafers was about half that on fused quartz. Its dependence upon theoxide thickness (0.2 μm to 1.0 μm) was not significant for scan speeds under10 cm/sec. Similarly, the variation in strain with scan speed was very smallfor speeds below 10 cm/sec. Scan speeds above 50 cm/sec caused significantincreases in the strain.

The measured strain was reduced by high temperature anneals. A 1100°C annealreduced the average strain by 60% and caused a clear reduction in grainimperfections (as determined by diffracted beam width). However, a 900'Canneal increased the diffracted beam widths even though the average strainwas reduced by about 30%.