Influence of growth pressure on filling 4H-SiC trenches by CVD method

• Published in: Japanese Journal of Applied Physics Vol. 55; no. 1S; pp. 1 - 4
• Main Authors: Ji, Shiyang, Kojima, Kazutoshi, Kosugi, Ryoji, Saito, Shingo, Sakuma, Yuuki, Tanaka, Yasunori, Yoshida, Sadafumi, Himi, Hiroaki, Okumura, Hajime
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 01.01.2016
• Subjects: Flow rate; Formations; Mesas; Stress concentration; Supplying; Thickness ratio; Trenches; Voids
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.55.01AC04

To construct a superjunction structure consisting of p/n columns, narrow stripe-shaped trenches (∼1.5 µm wide and ∼4.7 µm deep) preformed on an n+ 4H-SiC substrate were filled by the hot-wall CVD method using a conventional gas reaction system, SiH4:C3H8:H2. The influences of growth pressure on the coverage distribution of epilayers and the corresponding filling efficiency (the thickness ratio of epilayers on trench bottom and mesa top) were investigated. Two benefits of increasing the growth pressure from 10 to 38 kPa were found: one is the reduced growth around the mesa surface, which lessens the risk of void formation; the other is a high filling rate as well as an improved filling efficiency up to ∼7. By supplying source gases at high flow rates, a void-free trench filling with a filling rate of ∼1.3 µm/h was successfully achieved at 38 kPa.