Kogdas' M. Development of methods and equipment for control of structural and geometrical perfection of gallium arsenide wafers

The thesis is devoted to the development of methods and equipment for control of structural and geometrical perfection of GaAs wafers. A method and an installation ?m-1 for the control of complex forms of GaAs wafers deformations using the method of interference and video system are developed. It has allowed reducing errors and automating the measurement process. First it is shown that the GaAs plate in the plane (100) is more rigid in the direction of <011> <001> and in comparison with the direction of <010>, because of operating main stresses in wafer , and due to the extremely small Poisson's ratio. It's determined that distribution of internal stresses in semi-insulating GaAs, which is used for the manufacture of optical lenses, has insular character, and it is allocated in the crystallographic directions [001] and [010]. It's established that for GaAs wafers oriented in the plane (100), the rigidity of the wafer is determined by the expression by Poisson's ratio and Young's module. These wafers in the direction [001] have the rigidity which is 26 % lower than in the direction [011]. Thus, the anisotropy of the elastic properties affects the magnitude and anisotropy of bending. It's established that during the processing of GaAs wafers of large diameter with orientation (100) there is a complex bending, epures of which have extremes in one of the crystallographic directions <001>. The total annual economic impact on the implementation of this act is 57 th.