(Invited) Growth and Characterization of 200 mm SiC Crystals and Substrates

Abstract

SiC power device technology has over the past years continued to gain massive interest in automotive and industrial applications. The majority of devices is today fabricated on 150 mm diameter substrates while the 200 mm diameter substrates still is at early stage in both development and in terms of mass production. An increase of 50 mm in the wafer diameter corresponds to a 78% larger area and then a corresponding increase of the number of devices per wafer. This change impacts on the productivity of a production line and therefore the cost of the final device can be reduced. Higher production volume and lower cost will lead to a further massive implementation of SiC based power devices in the automotive industry that today is rushing on the path of electrification.At STMicroelectronics we are an early adopter of 200 mm substrates since the first substrate was demonstrated in 2021. Development of 200 mm device quality substrates have progressed well and defect density are today in same range as for 150 mm substrates. The ramp up of production is now made in the new STMicroelectronics plant in Catania while R&D unit in Norrköping Sweden continue to further push the limits of the technology.In this paper, we report the latest progress on STMicroelectronics 200 mm diameter crystals and substrates. We will discuss the most suitable characterization routes available and how we can detect device affecting defects at an early stage. In particular we will start by describing the mechanism that is behind the crystal growth process together with the characterization methods that allow to control the quality of the ingot by monitoring the relevant properties (i.e. bulk defectivity, polytype composition, internal stress). We will then describe the main key parameters to be controlled on the substrate to be sure it is suitable for device making (i.e. mechanical behavior, resistivity, surface roughness, effectiveness of the surface preparation). We will also describe the CVD process that is used to grow on top of the substrate an epitaxial layer with proper resistivity and thickness tailored on the device we need to produce for specific applications. In conclusion we will show some data about the correspondence in between device failure and defectivity on both substrate and epitaxial layer. A comparison of the results collected on both 6” and 8” substrates will be reported to show the excellent job performed in our R&D department in Norrköping to increase the wafer size maintaining the same level of quality. On the other side, our production line in Catania is going to be the first of this kind in Europe with a vertical integration that guarantee process control from the SiC powder to the design and characterization of the final power device.