Curvature and bow of III-N HEMT structures during epitaxy on silicon substrates

Structure growth, surface, and interfaces

High Electron Mobility Transistor (HEMT) heterostructures based on III-N semiconductors (nitrides of Al and Ga) have become increasingly widespread in recent years. They are used in the manufacture of microwave transistors, high- power transistors for power electronics, etc. However, mass application of such transistors requires a reduction in the cost of heterostructures due to the use of cheap substrates and an increase in the area of one substrate. Thus,  substrates of single-crystal Si(111) are of great interest. They are available in diameters up to 300 mm, and the possibility of growing III-N structures has already been demonstrated for them. Nevertheless, the epitaxy of III-N HEMT  structures on Si substrates is complicated due to a number of technological difficulties in the epitaxy of such structures. In this paper, the dynamics of curvature and residual bow of III-N HEMT structures were experimentally studied during epitaxy and after cooling for Si(111) substrates with a diameter of 100 mm and various thicknesses of substrates and grown semiconductor films. It has been shown that the technology developing and optimization should be  carried out on thin substrates, while device structures should be grown on thick substrates. Furthermore, the mechanical stresses can be controlled accurately enough so after epitaxy the bow of the structure is minimal.