SANTA CLARA, Calif. (AP) -- Applied Materials Inc. said Tuesday it offered to buy Montana-based Semitool Inc. for $364 million in cash, a move the company says will broaden its portfolio of chip manufacturing equipment.

Applied Materials CEO Mike Splinter said the acquisition will help the company tap the growing market for semiconductors that go into mobile gadgets including "smart" phones and notebook computers.

"With this acquisition, Applied will help the world's leading chip makers create ever-smaller and more powerful devices," Splinter said.

"As part of Applied Materials, we can accelerate the global adoption of the technologies Semitool has developed," said Ray Thompson, chairman of Semitool. "With this agreement, we are providing our employees with a strong future and our stockholders with exceptional value."

Applied Materials, based in Santa Clara, Calif., said it will offer Semitool shareholders $11 per share, a 31 percent premium over the company's Monday closing share price of $8.40.

For the deal to be approved, Applied Materials needs two thirds of Semitool shareholders to accept the offer, which the companies expect to close by the end of the year. About 32 percent of Semitool's shares are held by its directors and executives, who have already agreed to tender their stake.

Semitool, based in Kalispell, Mont., saw shares jump $2.56, or 30 percent, to $10.96 in premarket trading Tuesday. The stock has ranged from $1.86 to $9.73 over the past year.

Semitool, which was founded 30 years ago, has about 800 employees, including just over 500 in Kalispell and Libby, Mont.