IBM goes mainstream with slice manufacturing

02/01/1999

IBM goes mainstream with SiGe manufacturing

IBM has moved silicon germanium (SiGe) technology into high-volume, mainstream manufacturing on 200-mm wafers at its Burlington, VT, facility. Until now, the benefits of SiGe techno-logy have been relegated to alternative, specialty ICs, particularly for mainframe computing applications, manufactured in pilot production.

IBM is producing an array of key ICs suitable for the wireless business and consumer communications products. The new SiGe-based ICs from IBM include low-noise amplifiers, voltage controlled oscillators, power amplifiers, and discrete transistors - all basic "building block" components found in most wireless product designs. Several of these ICs are lower-cost, highly-reliable direct replacements for gallium arsenide (GaAs) ICs, which despite their years of development and production experience are still considered "more costly and power-hungry," says an IBM official.

Unlike GaAs, SiGe processing is done on existing "silicon" production lines with minimal changes and retooling. As these chips enter the marketplace, consumers are likely to benefit from cellular phones, pagers, and other wireless communications devices that have extended battery life, carry out multiple functions, and are smaller, lighter, and less expensive. According to Dataquest, the production of wireless devices is expected to grow to over 450 million units annually by 2002. The opportunity for ICs that process RF signals alone is expected to reach $7 billion by 2002.

Along with this boost on SiGe manufacturing capacity, IBM is taking initiatives to apply silicon germanium technology to a broad spectrum of communications applications:

 IBM`s CommQuest subsidiary is designing SiGe-enhanced chip sets that will serve as the basis of next- generation cellular phones.

 Leica Geosystems and IBM are developing SiGe-based ICs for global positioning system products.

 IBM has a SiGe-based manufacturing and development relationship with Hughes Electronics, Harris Semiconductor, National Semiconductor, AMCC, NorTel, and Tektronix, for products from cell phones to satellites.

 Alcatel`s new fiber-optic system uses IBM SiGe technology to provide a

high-speed pipeline in communications networks.

The uniqueness of IBM`s SiGe process is that it uses ultra-high vacuum chemical vapor deposition (UHV-CVD), to grow SiGe films. This was a key to overcoming process difficulties, particularly growing a film with a graded Ge concentration across the transistor base region that is required for high-performance SiGe heterojunction bipolar transistors (HBT). This structure creates a ramped potential surface (a "drift field") that speeds electron conduction across the base region. The result is a supercharged transistor that operates at 65 GHz and higher.

The SiGe HBT also has higher current gain and improved output conductance

necessary for many analog applications. Some of the speed of this device can be traded for operation at lower power, allowing high performance, while decreasing energy requirements.

The HBT and an epi base are combined with advanced processing features of 3.3-V CMOS technology, 0.5-?m deep-UV lithography, deep and shallow trench isolation for improved device density and performance, and CMP of dielectric and metal layers for planarity of structures and wiring levels. - P.B.