X-RAY STRAIN MEASUREMENTS ON SEMI-CONDUCTORS. Paul F Fewster, Philips Research Laboratories, Cross Oak Lane, Redhill, U.K.

A combination of reciprocal space mapping and absolute lattice parameter determination can yield highly accurate and unambiquous strain measurements. Strain measurement are used extensively in x-ray diffraction for determining composition phase extent, layer relaxation and the presence of defects after ion implantation. The method most commonly used is the "rocking curve" method that assumes that the substrate has a known lattice parameter. Simulation of the "rocking curve" is necessary in most circumstances to separate strain from diffraction effects^[1].

Layer tilts can complicate this measurement considerably and a general tilt will lead to errors unless this is taken into consideration. However reciprocal space mapping in three-dimensions can resolve the complication of tilts^[2]. The uncertainties in the lattice parameter of the substrate are resolved by combining this reciprocal space mapping with a very high precision absolute lattice parameter method^[3]. Examples will be given to show how the strain in simple, complex and inhomogeneous semiconductors can be determined.

[1] Fewster & Curling (1987) J Appl. Phys. 62 4154

[2] Fewster & Andrew (1995) J Phys. D 28 A154

[3] Fewster & Andrew (1995) J Appl. Cryst. 28 451