David R. Greenberg

Self-aligned SiGe NPN transistors with 285 GHz f/sub MAX/ and 207 GHz f/sub T/ in a manufacturable technology

This paper reports on SiGe NPN HBTs with unity gain cutoff frequency (f/sub T/) of 207 GHz and an f/sub MAX/ extrapolated from Masons unilateral gain of 285 GHz. f/sub MAX/ extrapolated from maximum available gain is 194 GHz. Transistors sized 0.12/spl times/2.5 /spl mu/m/sup 2/ have these characteristics at a linear current of 1.0 mA//spl mu/m (8.3 mA//spl mu/m/sup 2/). Smaller transistors (0.12/spl times/0.5 /spl mu/m/sup 2/) have an f/sub T/ of 180 GHz at 800 /spl mu/A current. The devices have a pinched base sheet resistance of 2.5 k/spl Omega//sq. and an open-base breakdown voltage BV/sub CEO/ of 1.7 V. The improved performance is a result of a new self-aligned device structure that minimizes parasitic resistance and capacitance without affecting f/sub T/ at small lateral dimensions.

SiGe HBTs with cut-off frequency of 350 GHz

This work reports on SiGe HBTs with f/sub T/ of 350 GHz. This is the highest reported f/sub T/ for any Si-based transistor as well as any bipolar transistor. Associated f/sub max/ is 170 GHz, and BV/sub CEO/ and BV/sub CBO/ are measured to be 1.4 V and 5.0 V, respectively. Also achieved was the simultaneous optimization of f/sub T/ and f/sub max/ resulting in 270 GHz and 260 GHz, with BV/sub CEO/ and BV/sub CBO/ of 1.6 V and 5.5 V, respectively. The dependence of device performance on bias condition and device dimension has been investigated. Considerations regarding the extraction of such high f/sub T/ and f/sub max/ values are also discussed.

Interconnects in the third dimension: design challenges for 3D ICs

Despite generation upon generation of scaling, computer chips have until now remained essentially 2-dimensional. Improvements in on-chip wire delay and in the maximum number of I/O per chip have not been able to keep up with transistor performance growth; it has become steadily harder to hide the discrepancy. 3D chip technologies come in a number of flavors, but are expected to enable the extension of CMOS performance. Designing in three dimensions, however, forces the industry to look at formerly-two- dimensional integration issues quite differently, and requires the re-fitting of multiple existing EDA capabilities.

A 210-GHz f/sub T/ SiGe HBT with a non-self-aligned structure

A record 210-GHz f/sub T/ SiGe heterojunction bipolar transistor at a collector current density of 6-9 mA//spl mu/m/sup 2/ is fabricated with a new nonself-aligned (NSA) structure based on 0.18 /spl mu/m technology. This NSA structure has a low-complexity emitter and extrinsic base process which reduces overall thermal cycle and minimizes transient enhanced diffusion. A low-power performance has been achieved which requires only 1 mA collector current to reach 200-GHz f/sub T/. The performance is a result of narrow base width and reduced parasitics in the device. Detailed comparison is made to a 120-GHz self-aligned production device.

Foundation of rf CMOS and SiGe BiCMOS technologies

This paper provides a detailed description of the IBM SiGe BiCMOS and rf CMOS technologies. The technologies provide high-performance SiGe heterojunction bipolar transistors (HBTs) combined with advanced CMOS technology and a variety of passive devices critical for realizing an integrated mixed-signal system-on-a-chip (SoC). The paper reviews the process development and integration methodology, presents the device characteristics, and shows how the development and device selection were geared toward usage in mixed-signal IC development.

Manufacturability demonstration of an integrated SiGe HBT technology for the analog and wireless marketplace

Early production results are reviewed for IBMs integrated SiGe HBT technology. With a sample size of over 200 wafers, statistical control of key HBT parameters (F/sub T/, F/sub max/, R/sub bb/, R/sub bi/, /spl beta/) and other supporting devices, and benchmark circuit performance are shown. HBT device yield and reliability on 200 mm wafers are presented, demonstrating that the SiGe HBT is capable of meeting manufacturing requirement for the high performance wireless communications marketplace.

SiGe heterojunction bipolar transistors and circuits toward terahertz communication applications

The relatively less exploited terahertz band possesses great potential for a variety of important applications, including communication applications that would benefit from the enormous bandwidth within the terahertz spectrum. This paper overviews an approach toward terahertz applications based on SiGe heterojunction bipolar transistor (HBT) technology, focusing on broad-band communication applications. The design, characteristics, and reliability of SiGe HBTs exhibiting record f/sub T/ of 375 GHz and associated f/sub max/ of 210 GHz are presented. The impact of device optimization on noise characteristics is described for both low-frequency and broad-band noise. Circuit implementations of SiGe technologies are demonstrated with selected circuit blocks for broad-band communication systems, including a 3.9-ps emitter coupled logic ring oscillator, a 100-GHz frequency divider, 40-GHz voltage-controlled oscillator, and a 70-Gb/s 4:1 multiplexer. With no visible limitation for further enhancement of device speed at hand, the march toward terahertz band with Si-based technology will continue for the foreseeable future.

Measurement and modeling of thermal resistance of high speed SiGe heterojunction bipolar transistors

Thermal resistance has been measured for high speed SiGe HBTs with various emitter widths and lengths. The smaller devices exhibited higher thermal resistance values, but eventually resulted in lower junction temperature rise for a given power density. A physical model has been developed which showed good agreement with the measurements. The model indicates that the thermal resistance depends strongly on the deep trench geometry. The thermal resistance is also anticipated to increase with the existence of adjacent devices due to a heat dissipation interference, according to the model.

Scaling of SiGe Heterojunction Bipolar Transistors

Scaling has been the principal driving force behind the successful technology innovations of the past half-century. This paper investigates the impacts of scaling on SiGe heterojunction bipolar transistors (HBTs), which have recently emerged as a strong contender for RF and mixed-signal applications. The impacts of scaling on key performance metrics such as speed and noise are explored, and both theory and data show that scaling, both vertical and lateral, has mostly beneficial effects on these metrics. However, it is shown that the scaled devices are increasingly vulnerable to device reliability issues due to increased electric field and operation current density. Bipolar transistor scaling rules are reviewed and compared with accumulated reported data for verification. A review of scaling limits suggests that bipolar scaling has not reached the physical fundamental limit yet, promising a continued improvement of bipolar performance in the foreseeable future.

A 0.18 /spl mu/m 90 GHz f/sub T/ SiGe HBT BiCMOS, ASIC-compatible, copper interconnect technology for RF and microwave applications

We present a self-aligned, 0.18 /spl mu/m emitter width SiGe HBT with f/sub T/ of 90 GHz, f/sub MAX/ of 90 GHz (both at V/sub CB/=0.5 V), NF/sub MIN/ of 0.4 dB, and BV/sub CEO/ of 2.7 V. We also demonstrate that this device is integrable with IBMs 0.18 /spl mu/m, 1.8/3.3 V copper metallization CMOS technology with little effect on the CMOS device properties and design rules.