Ohmic Contacts for High Temperature Integrated Circuits in Silicon Carbide

in English ..........................................................................................................................................I Svensk sammanfattning ............................................................................................................................... II Acknowledgement ........................................................................................................................................ III List of papers ................................................................................................................................................. V 1. Chapter 1 – Introduction ....................................................................................................................... 1 1.1. Silicon Carbide – the material characteristics ............................................................................. 2 1.2. SiC Crystals .................................................................................................................................... 3 1.3. Growth and doping........................................................................................................................ 4 2. Chapter 2 – Metal – Semiconductor contacts ...................................................................................... 7 2.1. The Schottky barrier...................................................................................................................... 7 2.2. Mechanisms for carrier transport ................................................................................................ 8 2.3. Ohmic Contacts ............................................................................................................................. 9 2.4. Test structures for contact resistance measurements ............................................................... 10 2.4.1. The transfer length method – TLM ........................................................................................ 10 2.4.2. Cross-bridge Kelvin resistor structure ................................................................................... 12 2.5. Contact metallization .................................................................................................................. 13 2.5.1. Earlier work at KTH ................................................................................................................ 14 2.5.2. Contacts in the in-house IC-process ...................................................................................... 14 2.5.3. CoSi2 as a silicide for ohmic contacts ..................................................................................... 14 3. Chapter 3 – Experimental .................................................................................................................... 17 3.1. Wafers and epitaxial layers of the samples ................................................................................ 17 3.2. Mask sets ...................................................................................................................................... 18 3.2.1. Mask sets for TLM structures ................................................................................................. 18 3.2.2. Mask set for Schottky diodes .................................................................................................. 19 3.3. Experimental – sample processing ............................................................................................20 3.4. Electrical measurements – 2 or 4 probe techniques ................................................................. 21 3.5. Experimental work in Paper I ..................................................................................................... 22 3.5.1. “TLM samples” Paper I ........................................................................................................... 22