Sub-micron VLSI Power Technologies Presented at Hawaii Conference

At the recent 8th International Symposium on Power Semiconductor Devices and ICs, SGS-THOMSON Microelectronics previewed the next generation mixed power technologies.

Called BCD5 and CD5, the new sub-micron technologies apply an innovative approach that makes it possible to create power DMOS body regions in a VLSI CMOS process without the thermal treatment used in previous processes. The secret is a large-angle tilt implant -- a cold treatment which is compatible with the most delicate CMOS non-volatile memory structures.

Designed for 0.6 micron lithography, the BCD5 process combines precise bipolar circuits, very dense CMOS logic, efficient DMOS power stages and EPROM/EEPROM/Flash memory. Since it is compatible with SGS-THOMSON's CMOS logic and memory structures existing library cells can be used in a BCD5 circuit. But unlike processes which simply add high current outputs to a logic process, BCD5 is a true VLSI Power technology suitable for circuits working on supply voltages up to 40V. This limit can be raised to 80V when needed by adding extra mask steps.

A simplified version of the process called CD5 has been designed for those circuits which do not need high performance bipolar functions. In this version the epitaxial and buried layers are omitted, simplifying the process and making the process more cost-effective. The BCD5/CD5 technology family is also modular in other ways, so the minimal number of masks can always be used. For example, additional masks to the basic mask set 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 extremely complex smart power ICs containing analog digital and power functions plus microprocessor cores and sizable memories. In the automotive field it could be used to make very dense engine control units, sophisticated smart sensors and single-chip smart switches for multiplex wiring, while in the computer peripheral field it could be used to make very highly integrated solutions for hard disk drives. In the consumer field it can be use to make single-chip camera controllers, sophisticated audio amplifiers and home automation network nodes.

VLSI Power solutions are likely to be most effective in those applications where space is very limited, such as compact cameras, portable computers and automotive smart connectors. It will also be very effective in reducing the number of interconnections between chips, trading reduced packaging and assembly costs for an increase in silicon cost.

Bipolar-CMOS-DMOS "BCD" technology was pioneered by SGS-THOMSON in the mid eighties when technologists merged DMOS transistor technology with conventional junction-isolated bipolar IC technology. The resulting technology united the benefits of precise bipolar circuits, dense CMOS logic and high efficiency DMOS power stages. Moreover, having all the contacts on the top of the die it allowed the integration of fully isolated DMOS power transistors and hence any power stage type, including bridges.

Because of the lower power dissipation of power DMOS, the advent of BCD technology brought the possibility of assembling power ICs in low cost DIP and SO packages. In addition, the reduced dissipation and dense CMOS signal circuits also made it possible to integrate very complex functions. Over the years the original BCD technology has evolved towards finer lithography, shrinking from 4 microns to 2.5, then 1.2 and now 0.6. In parallel the technology has become more flexible, adding new capabilities such as non-volatile memory to the original bipolar-CMOS-DMOS recipe.

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