Why the epitaxial layer is now being used in silicon manufacturing process?

Answer 1

Epitaxy

Epitaxy is the process of growing a crystal of a particular orientation on top of another crystal such that both have the same structural orientation. The resulting structure is described as an epitaxial layer. In 1951 Gordon Teal and Howard Christensen at Bell Labs developed a process, now called epitaxial deposition, to grow a thin layer of material on a substrate that continues the underlying crystalline structure. Sheftal', Kokorish, and Krasilov described similar work on germanium and silicon in the U.S.S.R. in 1957. At the urging of Ian Ross, a Bell Labs team led by Henry Theurer used chemical-vapor deposition to add a thin epitaxial layer of silicon between the base and collector of a transistor in 1960. This approach raised the transistor's breakdown voltage while dramatically increasing its switching speed, (1961 Milestone) two important circuit-design characteristics. The added manufacturing cost of the extra process step was more than offset by improvements in device performance. The technology was quickly transferred to Western Electric and used in manufacturing silicon transistors for electronic telephone switching in the Bell System. Epitaxy

Epitaxy is the process of growing a crystal of a particular orientation on top of another crystal such that both have the same structural orientation. The resulting structure is described as an epitaxial layer. In 1951 Gordon Teal and Howard Christensen at Bell Labs developed a process, now called epitaxial deposition, to grow a thin layer of material on a substrate that continues the underlying crystalline structure. Sheftal', Kokorish, and Krasilov described similar work on germanium and silicon in the U.S.S.R. in 1957. At the urging of Ian Ross, a Bell Labs team led by Henry Theurer used chemical-vapor deposition to add a thin epitaxial layer of silicon between the base and collector of a transistor in 1960. This approach raised the transistor's breakdown voltage while dramatically increasing its switching speed, (1961 Milestone) two important circuit-design characteristics. The added manufacturing cost of the extra process step was more than offset by improvements in device performance. The technology was quickly transferred to Western Electric and used in manufacturing silicon transistors for electronic telephone switching in the Bell System.