COINTEGRATION OF OPTOELECTRONICS AND SUBMICROMETER CMOS

The rapid emergence of multichip modules (MCM's) and the continuing in terest in wafer scale integration (WSI) provide important opportunitie s for successful insertion of high performance optical interconnection s into real systems. The large area substrates and the distances betwe en packaged wafer-level modules introduce distances of sufficient leng th that propagation of very high-speed digital signals along electrica l lines will be difficult. At the same time, the substrates allow use of thin film technologies for fabrication of optoelectronic devices, o ptical waveguides, and other optical elements, drawing on the natural alignment accuracy of photolithographic definition of optical componen ts to avoid several practical problems arising when optical elements a re surface mounted. For such reasons, large area silicon wafers provid e an important potential application for more aggressive use of optica l interconnections. An important issue is growth of GaAs semiconductor regions within a silicon WSI or MCM substrate containing high perform ance silicon CMOS circuitry, seeking to co-integrate optical and silic on VLSI devices. Experimental studies of submicrometer CMOS device cha racteristics following thermal simulation of GaAs heteroepitaxial grow th are summarized.