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Towards Silicon Carbide VLSI Circuits for Extreme Environment Applications
KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.
KTH, School of Electrical Engineering and Computer Science (EECS), Electronics.ORCID iD: 0000-0001-6459-749X
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2019 (English)In: Electronics, ISSN 2079-9292, Vol. 8, no 5Article in journal (Other academic) Published
Abstract [en]

A Process Design Kit (PDK) has been developed to realize complex integrated circuits in Silicon Carbide (SiC) bipolar low-power technology. The PDK development process included basic device modeling, and design of gate library and parameterized cells. A transistor–transistor logic (TTL)-based PDK gate library design will also be discussed with delay, power, noise margin, and fan-out as main design criterion to tolerate the threshold voltage shift, beta (β) and collector current (IC) variation of SiC devices as temperature increases. The PDK-based complex digital ICsdesign flow based on layout, physical verification, and in-house fabrication process will also be demonstrated. Both combinational and sequential circuits have been designed, such as a 720-device ALU and a 520-device 4 bit counter. All the integrated circuits and devices are fully characterized up to 500 °C. The inverter and a D-type flip-flop (DFF) are characterized as benchmark standard cells. The proposed work is a key step towards SiC-based very large-scale integrated (VLSI) circuits implementation for high-temperature applications.

Place, publisher, year, edition, pages
2019. Vol. 8, no 5
Keywords [en]
Process Design Kit (PDK); bipolar logic gates; high temperature digital integrated circuits (ICs); transistor–transistor logic (TTL); SiC bipolar transistor; SiC VLSI Circuits
National Category
Engineering and Technology Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-248424DOI: 10.3390/electronics8050496ISI: 000470999900027Scopus ID: 2-s2.0-85067024612OAI: oai:DiVA.org:kth-248424DiVA, id: diva2:1302981
Funder
Knut and Alice Wallenberg Foundation, Working on Venus
Note

QC 20190410

Available from: 2019-04-08 Created: 2019-04-08 Last updated: 2019-10-09Bibliographically approved
In thesis
1. Silicon Carbide High Temperature Photodetectors and Image Sensor
Open this publication in new window or tab >>Silicon Carbide High Temperature Photodetectors and Image Sensor
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Silicon Carbide (SiC) has the advantages of ultraviolet (UV) sensing and high temperature characteristics because of its wide band gap. Both merits make SiC photodetectors very attractive in astronomy, oil drilling, combustion detection, biology and medical applications. Driven by the objective of probing the high temperature surface of Venus (460 °C), this thesis develops SiC photodetectors and an image sensor for extremely high temperature functions. The devices and circuits are demonstrated through the procedure of layout design, in-house processing and characterizations on two batches.

The process flow has been optimized to be suitable for large scale integration (LSI) of SiC bipolar integrated circuits (IC). The improved processing steps are SiC dry etching, ohmic contacts and two-level metal interconnect with chemical-mechanical polishing (CMP). The optimized process flow is applied in the fabrication of discrete devices, a transistor-transistor logic (TTL) process design kit (PDK) and LSI circuits.

The photodetectors developed in this thesis, including photodiodes with various mesa areas, a phototransistor and a phototransistor Darlington pair have stable characteristics in a wide temperature range (25 °C ~ 500 °C). The maximum operational temperature of the p-i-n photodiode (550 °C) is the highest recorded temperature accomplished ever by a photodiode. The optical responsivity of the photodetectors covers the spectrum from 220 nm to 380 nm, which is UV-only.

The SiC pixel sensor and image sensor developed in this thesis are pioneer works. The pixel sensor overcomes the challenge of monolithic integration of SiC photodiode and transistors by sharing the same epitaxial layers and topside contacts. The pixel sensor is characterized from 25 °C to 500 °C. The whole image sensor circuit has 256 (16 ×16) pixel sensors and one 8-bit counter together with two 4-to-16 decoders for row/column selection. The digital circuits are built by the standard logic gates selected from the TTL PDK. The image sensor has 1959 transistors in total. The function of the image sensor up to 400 °C is verified by taking basic photos of nonuniform UV illumination on the pixel sensor array.

This thesis makes an important attempt on the demonstration of SiC opto-electronic on-chip integration. The results lay a foundation on the development of future high temperature high resolution UV image sensors.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. p. 81
Series
TRITA-EECS-AVL ; 2019:37
Keywords
Silicon Carbide (SiC), high temperature, photodetector, photodiode, phototransistor, ultraviolet (UV), transistor-transistor logic (TTL), bipolar junction transistor (BJT), integrated circuit (IC), pixel sensor, image sensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-248426 (URN)978-91-7873-160-2 (ISBN)
Public defence
2019-05-03, Ka-Sal B (Sal Peter Weissglas), Kistagången 16, Kista, 10:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation, Working on VenusSwedish Foundation for Strategic Research , CMP Lab
Note

QC 20190411

Available from: 2019-04-11 Created: 2019-04-09 Last updated: 2019-04-11Bibliographically approved
2. Process Design Kit and High-Temperature Digital ASICs in Silicon Carbide
Open this publication in new window or tab >>Process Design Kit and High-Temperature Digital ASICs in Silicon Carbide
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electronics such as microprocessors are highly demanded to monitor or control a process or operation in temperature critical (300 ºC to 600 °C) applications. State-of-the-art silicon-based integrated circuits (ICs) have been improved significantly throughout the years but mainly for a low-temperature ambient. At a temperature higher than 300 ºC silicon-on-insulator (SOI) or bulk silicon-based electronics cannot operate reliably. Therefore the wide bandgap (WBG) semiconductor materials such as silicon carbide (SiC) come into play.

In recent years, many types of SiC-based devices and low complex ICs have been reported and are operational at a high temperature (HT). The main goal of the thesis is to explore and demonstrate the feasibility of SiC-based circuits that are complex, dense and monolithically integrated for high-temperature applications such as a central-processing-unit (CPU).

This thesis work demonstrates a Process Design Kit (PDK) for the SiC-based large scale integrated (LSI) circuits implementation. It consists of discrete devices, gate and module library, and SiC ICs verification programs. The thesis work reports the PDK results over the full temperature range of 25 to 500 °C with a power supply of 10 V to 20 V.

The thesis work demonstrates a 4-bit CPU architecture designed for a proposed instruction set. Manual place and route with around 10,000 devices and area of 150 mm2 were carried out using the PDK standard cell library. The CPU and integral parts have been implemented at the transistor level using the PDK gate/module library and simulated from 25 to 500 °C. The CPU has been fabricated in the in-house low-power SiC bipolar process and measured at a high temperature.

The thesis work also reports reference analog and mixed-signal ICs. A 555-timer consisting of both digital and analog circuits has been designed, integrated and characterized up to 500 °C. Flash and SAR ADCs have been implemented using the PDK for HT applications. A 256-pixel image-sensor design and layout were also carried out using the PDK.

This thesis work is an important step and has laid the foundation of SiC-based LSI circuits realization for extreme environment applications.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. vii-xix, 148
Series
TRITA-EECS-AVL ; 2019:53
Keywords
Silicon Carbide, high-temperature digital integrated circuits, process design kit (PDK), bipolar logic gates, transistor-transistor logic (TTL), TTL CPU, bipolar transistor, LSI Circuits, ASICs
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-251766 (URN)978-91-7873-225-8 (ISBN)
Public defence
2019-06-14, Sal-B, Kistagången 16, Kista, 10:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20190521

Available from: 2019-05-21 Created: 2019-05-21 Last updated: 2019-05-21Bibliographically approved

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Shakir, MuhammadHou, ShuobenHedayati, RahelehMalm, B. GunnarÖstling, MikaelZetterling, Carl-Mikael

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