SUMCO
A silicon wafer specialist formed in 1999 by combining the wafer businesses of Sumitomo Metal Industries and Mitsubishi Materials. It is one of the two largest silicon wafer makers, with plants concentrated in Kyushu.
SUMCO・Materials・Last updated: October 15, 2026
Overview
SUMCO is headquartered in Minato, Tokyo. It grows silicon ingots and processes them into polished and epitaxial wafers, mainly in the 300 mm size used by advanced fabs.
Most of its plants are in Saga and Nagasaki prefectures in Kyushu, with additional sites in Yamagata and in Chitose, Hokkaido.
Business: Silicon wafers
Why it matters
Wafer supply is a single-material bottleneck: every chip starts on a silicon wafer, and Japan supplies a large share of them.
Its Chitose plant is in the same city as Rapidus's new fab.
Main products
- •Polished silicon wafers
- •Epitaxial silicon wafers
Sites in Japan
Head officeHeadquarters
Minato, Tokyo
Imari plantsPlant
Imari, Saga
Saga plantPlant
Kohoku, Saga
Nagasaki plantPlant
Omura, Nagasaki
Yonezawa plantPlant
Yonezawa, Yamagata
Chitose plantPlant
Chitose, Hokkaido