Abstract:
A bipolar transistor with raised extrinsic base and selectable self-alignment between the extrinsic base and the emitter (106) is disclosed. The fabrication method may include the formation of a predefined thickness of a first extrinsic base layer (102) of polysilicon or silicon on an intrinsic base (108). A dielectric landing pad (128) is then formed by lithography on the first extrinsic base layer (102). Next, a second extrinsic base layer (104) of polysilicon or silicon is formed on top of the dielectric landing pad (128) to finalize the raised extrinsic base total thickness. An emitter (106) opening is formed using lithography and RIE, where the second extrinsic base layer (104) is etched stopping on the dielectric landing pad (128). The degree of self-alignment between the emitter (106) and the raised extrinsic base is achieved by selecting the first extrinsic base layer (102) thickness, the dielectric landing pad (128) width, and the spacer width.
Abstract:
A high fT and fmax bipolar transistor (100) includes an emitter (104), a base (120), and a collector (116). The emitter has a lower portion (108) and an upper portion (1.12) that extends beyond the lower portion. The base includes an intrinsic base (140) and an extrinsic base (144). The intrinsic base is located between the lower portion of the emitter and the collector. The extrinsic base extends from the lower portion of the emitter beyond the upper portion of the emitter and includes a continuous conductor (148) that extends from underneath the upper portion of the emitter and out from underneath the upper portion of the emitter. The continuous conductor provides a low electrical resistance path from a base contact (not shown) to the intrinsic base. The transistor may include a second conductor (152) that does not extend underneath the upper portion of the emitter, but which further reduces the electrical resistance through the extrinsic base.
Abstract:
Methods for fabricating bipolar junction transistors, bipolar junction transistors made by the methods, and design structures for a bipolar junction transistor. The bipolar junction transistor includes a dielectric layer on an intrinsic base and an extrinsic base at least partially separated from the intrinsic base by the dielectric layer. An emitter opening extends through the extrinsic base and the dielectric layer. The dielectric layer is recessed laterally relative to the emitter opening to define a cavity between the intrinsic base and the extrinsic base. The cavity is filled with a semiconductor layer that physically links the extrinsic base and the intrinsic base together.
Abstract:
Es wird eine Halbleiterstruktur (100) mit einer Isolatorschicht (120) auf einem Halbleitersubstrat (110) und einer Nutzschicht (130) auf der Isolatorschicht beschrieben. Das Substrat (110) ist mit einer relativ geringen Dosis eines Dotanden (111) eines bestimmten Leitungstyps dotiert, sodass es einen relativ hohen spezifischen Widerstand aufweist. Außerdem kann ein der Isolatorschicht unmittelbar benachbarter Teil (102) des Halbleitersubstrats mit einer geringfügig höheren Dosis desselben Dotanden (111), eines verschiedenen Dotanden (112) desselben Leitungstyps oder deren Kombination (111 und 112) dotiert werden. Wahlweise werden innerhalb desselben Teils (102) Mikrokavitäten (122, 123) erzeugt, um eine Erhöhung der Leitfähigkeit durch eine entsprechende Erhöhung des spezifischen Widerstands zu kompensieren. Durch die Erhöhung der Dotandenkonzentration an der Grenzfläche Halbleitersubstrat/Isolatorschicht steigt die Schwellenspannung (Vt) von entstehenden parasitären Kapazitäten an, wodurch das Oberschwingungsverhalten verringert wird. Ferner werden hierin auch Ausführungsformen eines Verfahrens und einer Entwurfsstruktur für eine solche Halbleiterstruktur beschrieben.
Abstract:
Disclosed is semiconductor structure (100) with an insulator layer (120) on a semiconductor substrate (110) and a device layer (130) is on the insulator layer. The substrate (110) is doped with a relatively low dose of a dopant (111) having a given conductivity type such that it has a relatively high resistivity. Additionally, a portion (102) of the semiconductor substrate immediately adjacent to the insulator layer can be doped with a slightly higher dose of the same dopant (111), a different dopant (112) having the same conductivity type or a combination thereof (111 and 112). Optionally, micro-cavities (122, 123) are created within this same portion (102) so as to balance out any increase in conductivity with a corresponding increase in resistivity. Increasing the dopant concentration at the semiconductor substrate-insulator layer interface raises the threshold voltage (Vt) of any resulting parasitic capacitors and, thereby reduces harmonic behavior. Also disclosed herein are embodiments of a method and a design structure for such a semiconductor structure.