P. Schley

Novel collector design for high-speed SiGe:C HBTs

We describe a novel collector design for high-frequency SiGe:C HBTs without deep trenches and with low-resistance collectors formed by high-dose ion implantation after shallow trench formation. f/sub T/ values of 200 GHz at BV/sub CEO/=2.0 V and ring oscillator delays of 4.3 ps are obtained. Excellent static characteristics and high yield were achieved for the HBT module integrated in a 0.25 /spl mu/m CMOS platform.

A flexible, low-cost, high performance SiGe:C BiCMOS process with a one-mask HBT module

We demonstrate an extremely simple, flexible, and hence low-cost SiGe:C BiCMOS process with ample performance for the majority of high volume applications. This technology offers three HBT devices with f/sub T//BV/sub CEO/ values of 28 GHz/67 GHz/7.5 V; 52 GHz/98 GHz/3.8 V; and 75 GHz/ 90 GHz/2.4 V by adding only one mask to the underlying CMOS process.

SiGe:C BiCMOS technology with 3.6 ps gate delay

A high-speed SiGe:C HBT technology is presented that combines a new extrinsic base construction with a low-resistance collector design to simultaneously minimize base and collector resistances and base-collector capacitance. A ring oscillator delay of 3.6 ps per stage was achieved. To our knowledge, this is the shortest gate delay reported to date for a SiGe technology. The HBTs demonstrate an f/sub T/ of 190 GHz, an f/sub max/ of 243 GHz, and a BV/sub CEO/ of 1.9 V at an drawn emitter size of 0.175/spl times/0.84 /spl mu/m/sup 2/. The high-speed HBT module has been integrated in a 0.25 /spl mu/m CMOS platform.

Dopant diffusion in C-doped Si and SiGe: physical model and experimental verification

We show that B and P exhibit suppressed, and As and Sb enhanced diffusion in C-rich Si. This can be well described by coupled diffusion of C and Si point defects. We present a physical model for the impact of C on dopant diffusion in Si and SiGe and demonstrate its reliability in the context of device characteristics of heterojunction bipolar transistors, which constitute a most sensitive tests for dopant diffusion on the nm scale.

A complementary BiCMOS technology with high speed npn and pnp SiGe:C HBTs

We demonstrate SiGe:C pnp HBTs in a complementary bipolar CMOS flow with f/sub T//f/sub max/ values of 80 GHz/120 GHz at BV/sub CEO/ = 2.6 V and a ring oscillator delay of 8.9 ps. The simultaneously fabricated npn HBTs sustain no significant performance loss compared to the npn-only BiCMOS, confirmed by f/sub T//f/sub max/ values of 180 GHz/185 GHz and a ring oscillator delay of 4.6 ps. A pnp-only BiCMOS flow produces peak f/sub T//f/sub max/ values for pnp devices of 115 GHz/115 GHz. The high speed performance of the pnp transistors surpasses the best reported values of this transistor type substantially.

SiGe HBT module with 2.5 ps gate delay

We present a double-polysilicon SiGe:C HBT module showing a CML ring oscillator (RO) gate delay tau of 2.5 ps, and fT/ fmax/BVCEo values of 300 GHz/350 GHz/1.85V. A key new feature of the HBT module is a connection of the extrinsic and intrinsic base regions by lateral epitaxial overgrowth. This facilitates simultaneously a very low base resistance and a reduced base-collector capacitance. In addition, the RF performance is enhanced for devices rotated by 45deg with respect to the standard orientation due to favorable epitaxial growth behavior.

Modular integration of high-performance SiGe:C HBTs in a deep submicron, epi-free CMOS process

We will describe the first modular integration of a SiGe:C heterojunction bipolar transistor (SiGe:C HBTs) into a conventional 0.25 /spl mu/m, epi-free CMOS platform. The high temperature stability of base doping profiles in SiGe:C HBTs and an optimized collector linkage have allowed the modular integration of an npn device with f/sub T//f/sub max/ of 55/90 GHz into two variants of a conventional epi-free 0.25 /spl mu/m CMOS platform. In both cases, the original CMOS steps and the electrical parameters of the CMOS devices remain essentially unchanged. Yield and electrical characteristics of the integrated SiGe:C HBT are shown to be the same as those from a bipolar-only process.

The effect of carbon incorporation on SiGe heterobipolar transistor performance and process margin

We present the high-frequency characteristics of heterojunction bipolar transistors (HBTs) with SiGe:C base layers grown by molecular beam epitaxy (MBE). We demonstrate peak f/sub T//f/sub max/ values up to 75/65 GHz, and delay times per stage down to 15 ps for ring oscillators with integrated SiGe:C HBTs. The use of epitaxial SiGe:C layers instead of SiGe offers wider latitude in process margin, without affecting dc performance.

SiGe BiCMOS Technology with 3.0 ps Gate Delay

This work reports on a 130 nm BiCMOS technology with high-speed SiGe:C HBTs featuring a transit frequency of 255 GHz and a maximum oscillation frequency of 315 GHz at an emitter area of 0.17 x 0.53 mum². A minimum gate delay of 3.0 ps was achieved for CML ring oscillators. Breakdown voltages of the HBTs are measured to be BV_CEO=1.8 V, BV_CBO=5.6 V, andBV_EBO=1.9 V.

Carbon-containing group IV heterostructures on Si: properties and device applications

We review some important material properties of Si 1-y C y and Si 1-x-y Ge x C y layers grown pseudomorphically on Si(001). This new material might overcome some of the limitations of strained Si 1-x Ge y and open new fields for device applications of heteroepitaxial Si-based systems. In addition, we demonstrated incorporating low carbon concentrations (<10 20 cm -3 ) into the SiGe region of a heterobipolar transistor (HBT) can significantly suppress boron outdiffusion caused by later processing steps. The static characteristics demonstrate that the transistors should be suitable for circuit applications. Comparing the high-frequency performance of MBE-grown SiGe:C HBTs with identically SiGe HBTs we found an increase in f T and f max by a factor of more than 2 for our chosen SiGe profile. This indicates that adding carbon enabled one to use implantation steps without affecting the boron profile, that is, it offers wider latitude in process margins.