Self-Heating Characterization of SiGe:C HBTs by Extracting Thermal Impedances

Scaling influence on the thermal behavior of toward-THz SiGe:C HBTs

“…It is shown that R TH significantly increases by reducing L E and can grow beyond 10 4 K/W for small areas. This confirms the findings in [8], where some CBEBC devices fabricated by STMicroelectronics were characterized by using the DC extraction technique employed in this work, and in [9], where the thermal impedances were determined by resorting to small-signal Sparameter measurements. In particular, the smallest DUTs belonging to set #1 (A E =0.2×0.57 µm 2 ), #2 (A E =0.14×0.39 µm 2 ), and #3 (A E =0.11×0.63 µm 2 ) suffer from R TH =14300 K/W, R TH =21000 K/W, and R TH =22000 K/W, respectively.…”

“…The need for improving the performance of SiGe transistors has motivated a constant technological effort to allow aggressive lateral and vertical scaling. However, this is leading to unsustainable thermal issues induced by (i) the increase in current (and power) density, as clearly stated in a comprehensive review paper [6], and (ii) the reduction of the spacing between the intrinsic region and shallow/deep trenches filled with low thermal conductivity materials [7], for which the thermal resistances of single-finger transistors have been pushed into the thousands of K/W [8], [9]. This paper contributes to deepen the understanding of the scaling impact on the self-heating (SH) in SiGe:C HBTs by means of simple DC measurements carried out on state-of-the-art devices realized in the DOTFIVE framework.…”

Influence of Scaling and Emitter Layout on the Thermal Behavior of Toward-THz SiGe:C HBTs

“…In particular, the smallest DUTs of sets #1 ( A E = 0.2 × 0.57 μm 2 ), #2 (A E = 0.14 × 0.39 μm 2 ), and #3 ( A E = 0.11 × 0.63 μm 2 ) suffer from R TH = 14 300, 21 000, and 22 000 K/W, respectively. This confirms the findings in [11] and [13], where some collector-base-emitter-base-collector devices fabricated by STMicroelectronics were characterized using the extraction method employed in this paper [11] and by determining the thermal impedances through small-signal S-parameter measurements [13].…”

“…However, this is leading to unsustainable thermal issues induced by (i) the increase in current (and power) density, as clearly stated in a comprehensive review paper [4]; (ii) the reduction of the spacing between the intrinsic region and shallow/deep trenches filled with low thermal conductivity materials that inhibit the lateral propagation of the heat emerging from the basecollector space-charge region [5]- [8]; and (iii) the adoption of Manuscript a buried oxide layer to ensure full dielectric isolation [9], [10]. According to recent studies, the thermal resistances of single-finger transistors have been pushed into the thousands of K/W [11]- [13].…”

Experimental DC Extraction of the Base Resistance of Bipolar Transistors: Application to SiGe:C HBTs

“…This is the case for state-of-the-art SiGe:C HBTs, where the thermal resistances R TH have been pushed into the thousands of K/W [27], [29]- [31], and the openemitter breakdown voltage BV CBO has decreased down to 5-6 V and below [23], [24], [26], [27].…”