SGS-Thomson expands process tech

Electronic News, July 15, 1996 by Sarah Cohen

Lincoln, Mass.--SGS-Thomson Microelectronics has developed a new version of its BCD sub-micron technology. This latest version of the BCD process, dubbed BCD5 (up from BCD3) and recently exhibited at a symposium in Hawaii, has pushed SGS-Thomson's lithography progression down from 1.2-micron in BCD3 to 0.6-micron in the BCD5 process.

This shrinkage has allowed SGS-Thomson to add EEPROM capabilities to a process that already combines bipolar circuits, CMOS logic, DMOS power stages and EPROM/flash memory onto one device. The company has also developed a simplified version of the process called CD5, designed for those circuits which do not need high performance bipolar functions.

SGS-Thomson claims the processes make it possible to create power DMOS body regions in VLSI CMOS without using thermal treatment. "The secret is a large-angle tilt implant--a cold treatment which is compatible with the most delicate CMOS non-volatile memory structures," the company said.

George Fodor, product marketing manager for SGS-Thomson's Dedicated Products Group, said these new processes also present the possibility of building general purpose bridge drivers for motor control or power supply devices that customers can then program to meet their particular needs. The first products to implement these new processes are expected to be available in the next year-and-a-half to two years, according to Mr. Fodor.

Since BCD5 is compatible with SGS-Thomson's CMOS logic and memory structures, existing library cells can be used in a BCD5 circuit. Unlike processes which simply add high current outputs to a logic process, however, BCD5 is a true VLSI power technology suitable for circuits working on supply voltages up to 40V, the company said. In addition, this limit can be raised to 80V when needed by adding extra mask steps.

In the CD5 version, the epitaxial and buried layers are omitted, simplifying the process. The BCD5/CD5 technology family is also modular in other ways, so the minimal number of masks can always be used. Additional masks can be optionally used when a circuit design calls for higher voltage transistors, higher current DMOS, faster NPN transistors and other structures.

BCD5 and CD5 are suitable for integrating smart power ICs containing analog digital and power functions plus microprocessor cores and sizable memories. In the automotive field, they can be used to make dense engine control units, smart sensors and single-chip smart switches for multiplex wiring. Additional applications include computer peripherals and consumer products such as single-chip camera controllers.

Mr. Fodor said bipolar-CMOS-DOMS BCD technology was first conceived by SGS-Thomson in the mid-eighties as a way to "deal with the shortcoming of the individual technologies as they stood. They all had pluses and minuses. In a system, the processing core and interface devices needed an actuator. The system needed memory and a power supply. Before BCD, people used these different techniques in different parts of the system in a variety of packages. That's not very efficient if you can put the whole thing onto a single piece of silicon."

Because of the lower power dissipation of power DMOS, the advent of BCD technology brought the possibility of assembling power ICs in DIP and SO packages. Over the years, the original BCD technology has evolved toward finer lithography, shrinking from 4 microns to 2.5, then 1.2 and now 0.6. In parallel, new capabilities have been added, such as non-volatile memory.