Micron Technology Inc., one of the world's largest memory chipmakers, is creating 860 high-tech jobs as part of a $1.2 billion upgrade of its manufacturing plant in Manassas, the company announced yesterday in a news conference with Virginia Gov. Mark R. Warner (D).

The new employees will help the Idaho-based firm produce larger memory chips at the plant, which employs about 1,100 people.

"This is a big chunk of high-tech, high-paying jobs. This is what happens when you swing for the fences in economic development," Warner said in an interview. He called Micron's decision to upgrade the Manassas facility "one more step in the emergence of Prince William County as a world-class technology center."

Micron's new job openings will range from factory technicians who will make $35,000 a year and up to engineers who will command more than $90,000 annually, company officials said. Most of the new hires will be engineers, they said.

The hiring comes two years after Micron -- hit hard by a downturn in the computer chip industry -- fired 550 workers at the Manassas plant.

Micron makes semiconductor components used in consumer goods such as personal computers and cellular telephones. Its Manassas facility is based in a growing cluster of high-tech companies, as well as George Mason University's Prince William campus.

"I remember Prince William used to be tract suburban housing, where people would commute to town," Warner said. "But now, seeing this facility and going by the George Mason facility, this is the envy of anything in the region."

Warner said he noticed during a recent drive to a fundraiser near Woodbridge that many of the tract houses have been replaced by "homes you would think of as being in McLean and Great Falls. But they were in Prince William. So this is really a community that has come of age."

Micron has operations in 18 countries in Europe and Asia, in addition to the United States. It has been making a transition from manufacturing eight-inch silicon wafers -- used in the production of memory chips -- to 12-inch wafers that are more marketable. Micron reported earnings of $188 million in fiscal 2005, which ended Sept. 1, up from $157.2 million a year earlier.

Chairman and chief executive Steven R. Appleton said Micron chose to upgrade the Manassas plant, as opposed to one elsewhere, because of tax incentives offered by Virginia and the ready supply of "educated" workers in the Washington region.

According to Warner, Micron is eligible for a performance grant of more than $25 million, based partly on the number of new jobs it creates in the future.

"There are going to be people around the world who will work for a cheaper wage rate, so we have to show that we have a better educated and more innovative workforce," Warner said.

The incentive package was negotiated by the City of Manassas and the Virginia Economic Development Partnership.

As part of the deal, Virginia also will provide a $2 million grant to support the City of Manassas in workforce development and a $2 million education grant that will be used, in part, to bolster training programs at higher education institutions, including George Mason, Northern Virginia Community College and Virginia Tech.

Chairman Steven R. Appleton said Micron considered tax incentives and the region's workforce."This is a big chunk of high-tech, high-paying jobs," Virginia Gov. Mark R. Warner (D) said.