THOMAS TOWNSHIP, Mich. (AP) — A Michigan-based silicon products company says it's making permanent the layoff of 400 workers at sites in Michigan and Tennessee, a move forced by a supply glut and trade conflicts with China.

Hemlock Semiconductor Corp. announced the layoffs in January and now says they'll be permanent. They affect 300 employees at a site in Clarksville, Tenn., and 100 at its home base in Saginaw County's Thomas Township, near Saginaw.

Spokesman Jarrod Erpelding tells MLive.com (http://bit.ly/WtfiPa) that there's no sign of resolution of the trade disputes that led to the job cuts.

The company makes high-purity silicon materials for use by semiconductor and solar ingot/wafer manufacturers.