KLA-Tencor Corporation is a global capital equipment company based in Milpitas, California. It supplies process control and yield management systems for the semiconductor industry and other related nanoelectronics industries. The company's products and services are intended for all phases of wafer, reticle, integrated circuit (IC) and packaging production, from research and development to final volume manufacturing.

KLA-Tencor’s products and services are used by the vast majority of bare wafer, IC, reticle and disk manufacturers around the world. These customers rely on KLA-Tencor’s inline unpatterned and patterned wafer defect monitoring, review and classification; reticle defect inspection and metrology; packaging and interconnect inspection; critical dimension (CD) metrology; pattern overlay metrology; film thickness, surface topography and composition measurements; measurement of in-chamber process conditions; wafer shape and stress metrology; computational lithography tools; and, overall yield and fab-wide data management and analysis systems.

KT Services is the company’s global service network that maintains the productivity and performance of the extensive installed base of KLA-Tencor tools.

In 2000 the company formally established the KLA-Tencor Foundation, its philanthropic arm. KLA-Tencor Foundation supports and benefits the global communities in which KLA-Tencor employees live and work.

KLA-Tencor was formed in 1997 through the merger of KLA Instruments and Tencor Instruments, two companies in the semiconductor equipment and yield management systems industry. KLA Instruments was founded in 1975 by Ken Levy and Bob Anderson, and focused on defect inspection solutions. Karel Urbanek established Tencor Instruments in 1977 with an emphasis on metrology solutions, later adding John Schwabacher as cofounder.

Since the merger, which was valued at $1.3 billion, KLA-Tencor has acquired 19 additional companies:

In October 2015, Lam Research Corporation announced plans to buy KLA-Tencor for $10.6B, in what was viewed as a semiconductor industry consolidation move. In October 2016, the company announced it had terminated its offer for KLA-Tencor amidst concerns that the deal would not meet regulatory approval from the U.S. Department of Justice over antitrust concerns.

KLA-Tencor’s defect inspection and metrology products and related offerings can be broadly categorized into the following groups: Chip Manufacturing, Reticle Manufacturing, Data Storage Media/Head Manufacturing, LED Manufacturing, Compound Semiconductor Manufacturing, Microelectromechanical Systems (“MEMS”) Manufacturing, and Surface Profilometry and Metrology. KLA-Tencor also provides refurbished tools as part of its K-T Certified™ program

The market for yield management and process control systems is characterized by rapid technology development and product innovation. KLA-Tencor employs a large staff of full-time engineers and scientists and invests heavily in product research and development.

KLA-Tencor's global operations include manufacturing, support and R&D facilities throughout Europe, the United States, Japan and Asia/Pacific.