1998-11-09, BG9804,
Technical Backgrounder from Philips Semiconductors

Philips Semiconductors, the largest European semiconductor company, announces details of its QUBiC3 BiCMOS process technology that sets new standards in high-speed performance for silicon ICs and can achieve an f_max of around 70GHz. This is roughly double the industry norm of about 30 to 40GHz and is comparable with Silicon Germanium or Gallium Arsenide ICs but at around two-thirds the price. Capable of integrating high frequency RF bipolar circuitry and high speed CMOS logic blocks onto a single chip, this new process technology will be used to make a new range of high speed, high reliability, high performance RF front end ICs scheduled for release next year. These will enable Philips Semiconductors to maintain a leading position in the highly aggressive, mobile telecommunications marketplace.

QUBiC3 combines Philips Semiconductors' expertise in volume CMOS production with advances in high-speed bipolar technology to create a flexible and robust process technology. The CMOS part is currently provided by a mature 0.5 micron (0.42 micron effective gate length) process that is supported by a comprehensive set of design libraries and tools. The bipolar part uses an improved, double-polysilicon technology with an effective emitter geometry of less than 0.3 micron, plus self-aligned silicides and a low capacitance interconnect system.

QUBiC3's higher speeds and improved functionality are provided by optimising the mix of CMOS and bipolar capabilities, while the technology's high-quality passive components provide enhanced design flexibility and systems integration that can be used, for example, to produce lighter, more compact and less expensive phone systems. Furthermore, since the tremendous speed of QUBiC3 can be achieved at very low operating currents, power consumption can be minimised and battery life extended. The benefits of this advanced BiCMOS technology will not only apply to ICs made for telecommunications applications but also to ICs for other areas, such as TV, paging and video teleconferencing.

A key factor in achieving the excellent RF performance of the QUBiC3 technology is an interconnect system utilising a special dielectric material, HSQ (hydrogen silsesquioxane), that has a particularly low dielectric constant of 3.0. This is used as the insulating material between the metal layers and gives approximately 45 percent less capacitance than traditional insulating materials with dielectric constants of about 4.0. The result is a reduced parasitic capacitance that improves high frequency performance. This unique feature, combined with QUBiC3's ability to achieve high-speed switching and extremely low noise figures of only 0.6 dB, means that QUBiC3 is the ideal process technology to make ICs for low-noise amplifier (LNA) designs and mobile telecommunications applications.

QUBiC3 technology is particularly appealing to IC designers because it provides a wide range of resistors and capacitors, giving plenty of flexibility for designers, and yet still providing good matching characteristics to ensure high yields and manufacturability. In addition, a thick fourth metal layer has been specially developed and optimised for high-performance inductors. This frees designers from the need to rely on external components and results in considerably lower costs and higher levels of integration. As an example, on-chip inductors with Q factors of greater than 20 have been easily achieved, which, coupled with the inherently fast switching speeds of the transistors, provides an excellent platform for the design of RF ICs.

Until the arrival of QUBiC3, such high-speed performance was traditionally achieved by using more exotic compound semiconductor materials such as gallium arsenide (GaAs) or silicon germanium (SiGe). However, Philips Semiconductors, which has extensive research experience in both and also manufactures GaAs ICs, comments that both of these technologies can be complex and expensive to produce. For example, a GaAs- or SiGe-based IC can cost up to 50 percent more than a comparable IC made using QUBiC3, which only requires standard, reliable, high yield silicon processing techniques. Complex SiGe technologies, which may still be limited to only two metal interconnect layers, can require up to 30 masking layers to produce; while the same performance, but with twice as many layers of interconnect, can be obtained with QUBiC3 using only 26 masking stages - an important factor in the lower cost.

Theo Claasen, Philips Semiconductors' Chief Technology Officer, said, "Our new QUBiC3 technology is an excellent example of Philips Semiconductors' commitment to providing its customers with leading-edge ICs at extremely competitive prices. The strategic importance of such technologies in the marketplace is so strong, especially for creating ultra fast RF front end ICs for the mobile phone market, that we can already see a significant demand for this new generation of QUBiC technology. The first ICs made using QUBiC3 will be specified with an f_max of 60GHz and our researchers in Albuquerque, who developed this technology, have shown that it can achieve an f_max of 70GHz."

Philips Semiconductors' QUBiC3 technology

Parameter	pFET	nFET
Vt lin (Lg = 20 µm) (V)	-0.63	0.60
Vt sat (Lg = 0.5 µm) (V)	-0.61	0.64
Leff (µm)	0.43	0.42
gmsat (µS/µm)	36	132
IDsat (µA/µm)	150	338
toz (A)	123	123
lDsat ratio (nFET/pFET)	2.25

Parameter
RE (ohms)	10
RDB (kohms/sq)	19
Beta @ VCE = 0.72V	90
VA (V)	30
BVCEO (V)	4.0
BVCBO (V)	14.0
Peak ft (VCB = 1V) (GHz)	30 GHz
Peak fmax (VCB = 1V) (GHz)	70 GHz
3000 Yield array %	86%

Philips Semiconductors, a division of Royal Philips Electronics, headquartered in Eindhoven, The Netherlands, is the ninth largest semiconductor supplier in the world and the third largest supplier of discretes in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.