MBE as a production technology for HEMT LSIs
Abstract
Molecular beam epitaxy (MBE) is widely used to produce high quality epitaxial layers for advanced heterostructure devices. High electron mobility transistors (HEMTs) based on selectively-doped AlGaAs/GaAs heterojunction structures are one of the most successful applications of MBE. This paper reviews MBE techniques developed in our laboratories for HEMT LSI fabrication. To meet material requirements for submicron-gate AlGaAs/GaAs HEMT LSIs, we designed a multiwafer MBE system that enables good uniformity and high throughput. Epitaxial growth is done simultaneously on three 3-inch wafers mounted in a 7.5-inch holder. The variations of layer thickness and carrier concentration over the holder area were less than ±1%. One-touch substrate mounting without indium solder was developed for the t.5-inch holder. In-situ monitoring of growth rates by RHEED instensity oscillation with an automated growth system was introduced to control epitaxial parameters precisely. The density of oval defects due to Ga sources was stably controlled to less than 10 cm -2 and carrier depletion at the substrate-epitaxial layer interface was significantly reduced. These excellent material characteristics make it possible to develop high-performance HEMT logic and memory LSI circuits.
- Publication:
-
Journal of Crystal Growth
- Pub Date:
- February 1989
- DOI:
- 10.1016/0022-0248(89)90408-9
- Bibcode:
- 1989JCrGr..95..309K