展览31.1首席执行官的认证根据2002年的Sarbanes-Oxley法案第302章，Kenneth L. Schroeder认证：1。我已审查了本次季度关于KLA-Tencor Corporation的形式10-Q的报告;基于我的知识，本报告不包含任何未知的重要事实陈述或省略鉴于制定此类陈述的情况，阐明所需的重大事实，而不是误导本报告所涵盖的时期;3.根据我的知识，财务报表和本报告中包含的其他财务信息，所有物质公平出现尊重财务状况，截至此类报告者的财务状况，运营业绩和现金流量报告;4.注册人的其他证明总监及我负责建立和维护披露管制和程序（如汇票法规13A-15（E）和15D-15（E））为注册人提供：a：a）设计了这样的披露控制和程序，或者导致在我们的监督下设计的披露控制和程序，以确保在这些实体中的其他人中已知与我们联系的注册人（包括其综合子公司）的材料信息，特别是在这些实体中，特别是期间准备这份报告的期限;b）评估了注册人披露管制和程序的有效性，并在本报告中提出了我们关于披露管制和程序的有效性的结论，截至本报告涵盖的基于此类评估的期限结束;C）在本报告中披露，注册人在注册人最近的财政季度（注册人第四财年）内发生的财务报告内部的任何变化，这些财务报告（在年度报告的年度报告的年度报告中）或合理可能会有 materially affect, the registrant's internal control over the financial reporting; and 5. The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions): a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting. November 7, 2003 /s/ KENNETH L. SCHROEDER - -------------------- ---------------------------------- (Date) Kenneth L. Schroeder Chief Executive Officer (Principal Executive Officer)