André Perrotin

A high-speed low 1/f noise SiGe HBT technology using epitaxially-aligned polysilicon emitters

A 200 mm 0.35 /spl mu/m silicon-germanium heterojunction bipolar transistor (SiGe HBT) technology involving epitaxially-aligned polysilicon emitters is described. The devices are shown to combine the high speed performances typical for poly-Si emitter SiGe base devices (f/sub max/ up to 70 GHz) and the low 1/f noise properties of monocrystalline emitter structures (noise figure-of-merit KB as low as 7.2/spl times/10/sup -10/ /spl mu/m/sup 2/). Statistical current gain data are used to demonstrate the manufacturability of this innovative SiGe HBT technology.

230 GHz self-aligned SiGeC HBT for 90 nm BiCMOS technology

This paper describes a 230 GHz self-aligned SiGeC HBT featuring a selective epitaxial base and an arsenic-doped monocrystalline emitter. These technical choices are presented and discussed with respect to BiCMOS performance objectives and integration constraints.

BiCMOS6G: a high performance 0.35 /spl mu/m SiGe BiCMOS technology for wireless applications

BiCMOS6G, a 200 mm 0.35 /spl mu/m SiGe BiCMOS technology, is presented. This technology features a low complexity double-poly SiGe HBT with 60 GHz f/sub max/, added to stand-alone CMOS and high-quality passive components. It is ideally suited to the development of highly integrated wireless communications circuits.

Substrate resistance effect on the Fmax parameter of isolated BJT in BiCMOS process

High frequency test structures for bipolar devices with several guard ring configurations are described. Using these structures, the substrate effect on merit figures such as Ft and Fmax has been studied experimentally and compared to Microwave Design System (MDS) electrical simulations. A worst case for guard ring position is proposed, providing up to 15 GHz Fmax degradation.

A 0.13μm thin SOI CMOS technology with low-cost SiGe:C HBTs and complementary high-voltage LDMOS

We demonstrate the integration, in 0.13μm thin SOI CMOS technology, of low-cost high-performance high-voltage LDMOS and HBT transistors. These specific devices are obtained, without affecting CMOS core process devices. Static and dynamic characteristics for both type of transistors are presented, showing state of the art devices suitable for RF/analog/digital system on chip integration.

High frequency mismatch characterization on 170GHz HBT NPN bipolar device

This paper describes a high frequency mismatch approach on BJT able to reach Ft=170GHz. All obtained results are complementary and all well linked with the mismatch extract from DC measurement and in good agreement with the model parameters. In order to extract these results, a new test structure and associated parameter extraction tool have been developed.

Impact of emitter resistance mismatch on base and collector current matching in bipolar transistors

Bipolar transistor matching is characterized at medium and high current levels using an HF test structure. We demonstrate the predominant impact of emitter resistance mismatch on base and collector current matching at high current. To this end, we simulate base and collector mismatch thanks to the experimental values of emitter access resistance and its variations. The results of these simulations are successfully compared to the experimental data.

Bandgap Engineering in SiGe:C HBTs For Power Amplifier Applications

Since the introduction of Germanium in Silicon Bipolar transistors, and more recently the introduction of Carbon, the base band gap of SiGe:C heterojunction Bipolar transistors have been engineered to enhance device performance, thereby making them suitable for a wide range of high speed analog and RF applications. In the most recent development of Power Amplifiers (PAs) for wireless communications applications, current gain roll-off at elevated temperatures in SiGe:C HBTs has become an issue. Circuit designers have to accommodate the thermal runaway instability by designing ballast resistors which helps getting a current handling capability. Moreover, designing a large ballast resistor leads to increase ruggedness, to improve second breakdown but leads to a degradation of the efficiency. An HBT whose current gain is insensitive to temperature can help alleviate these opposing constraints and has the benefit of reducing the requirement for emitter ballasting [1]. Considering that a silicon BJT’s gain has an opposite temperature dependence (its gain increases as temperature increases) compared to a typical Si:Ge HBT, Band Gap engineering studies have been performed on an SiGe:C HBT in order to get its temperature behavior between a HBT and a BJT (i.e. insensible). Figure 1 illustrates current gain roll off with temperature for a SiGe:C HBT based on a mature 0.25μm BiCMOS technology. Current gain dramatically decreases from 220@25°C to 140@125°C (measured at VBE = 0.75V). The observed current gain roll off is caused by the band gap grading in the base and by the doping profile in the E/B junction. Using an existing method for characterizing the bang gap narrowing in the base of the bipolar (which will be detailed in the final paper), band gap energies are extracted and summarized in Figure 2 [2]. From these energies we can estimate the amount of Ge at the quasineutral base edge of the emitter-base space charge region. Then, using the measured emitter and base doping concentration, we can calculate the required Ge concentration at the emitter base junction to synthesize a device with gain insensitive to temperature. For our emitter and base doping concentration, it has been found that a target value of 3% Ge at the E/B junction is required. An optimized SiGe:C base profile has been fabricated, and current gain versus temperature has been plotted in Figure 3. As expected the current gain is invariant over a wide range of temperatures [-25°C, 125°C]. Since we have lowered the Ge concentration at the E/B junction, the current gain is reduced and reaches a maximum value of 95@VBE = 0.75V. It should be pointed out that, in these experiments, no specific effort has been made to recover the high current gain values of the reference HBTs. Higher BVCEO is obtained (7.3V compared to 6.3V) at the expense to a slightly decrease of Ft (Figure 4). Product FtxBVCEO remains constant. In conclusion, we have shown that the band gap energy can be modified in a predictable way to achieve a current gain which is invariant with temperature, an important consideration for SiGe:C HBTs used in PA applications. The optimized device electrical characteristics, DC and HF are presented.

Suppression of boron transient-enhanced diffusion in SiGe HBTs by a buried carbon layer

The experiments described in this paper show that base broadening effects due to extrinsic base implantation in SiGe HBTs can be suppressed by introducing a buried carbon layer under the SiGe/Si base prior to epitaxy. They also demonstrate that SiGe HBTs with excellent static (/spl beta//spl times/V/sub AF//spl sim/10/sup 4/ V) and dynamic (f/sub T/B/spl times/BV/sub CEO//spl sim/200 GHz/spl times/V) characteristics can be fabricated using an epitaxially aligned in-situ-doped polysilicon emitter and an appropriately designed SiGe/Si base profile.