Interesting article (2006) about BAE Nashua facility. More here

''The strategy is to maintain a foundry for internal use that is open to outside customers on a selective basis to increase utilization,” comments P.C. Chao, Technical Director and Manager of Process Engineering. Designs are not on the level of complexity of CMOS logic. BAE Systems focuses more on performance issues such as minimizing channel temperatures, maximizing efficiency and reducing noise.''

''The technologies produced at Nashua are aimed at RF “front-end” applications, i.e. next to the antenna. Features sought include sensitivity, power, power-added efficiency (PAE), low noise figure and high dynamic range ( Table 1 and Table 2). These properties are subject to trade-offs which must be balanced differently for specific applications. For transmission, one generally wants high power amplification. Reception of sometimes very weak signals (often below the enemy's reception threshold) requires low noise amplification.''

''Nashua's GaAs processing of wafers up to 6 inches (150 mm) in diameter offers more than two times the area of the standard 4 inch (100 mm) substrate. Another big improvement has been automation resulting in higher device yields. BAE has also shrunk its gate length for the 6-inch PHEMT process from 0.15 μm to 0.1 μm in 2005 (Figure 3). A similar move from 3-inch to 6-inch for its 0.1 μm MHEMTs is planned in 2007. Gate length reduction allows devices to access higher frequency and/or lower noise performance. The critical gate level is defined through direct write electron beam lithography while all other levels are patterned with an ultraviolet i-line stepper. The semiconductor epitaxial layers are built up using molecular beam epitaxy (MBE).''