Some practical remarks on the design of experimental systems for expitaxial growth of Si, Ge and SiGe

Epitaxial growth of group IV semiconductors, especially silicon, is an important and very sensitive step in the manufacture of semiconductor devices. The epitaxial layer grows by the addition of atoms to a single crystal substrate in an ordered manner. Any interruption in this order would grow as a fault through many layers and may cause final device failure. The epitaxial system must therefore be designed so as to prevent such faults. Practical considerations concerning a design of an experimental system for growth from the gas phase are described, based on experience gained during its building and operation. The various system components and materials, the necessary instrumentation and system calibration are described. Problems of vacuum tightness of the system and purification of incoming gases are also included. Finally, the basic calculations for obtaining the necessary molar ratios in the reactor chamber so as to achieve the desired layer type and resistivity are reviewed. In the system described layers of Si, Ge or SiGe mixture of desired composition may be grown.