The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 10, 2001
Filed:
Nov. 07, 1996
Abstract
A silicon substrate is cleaned using a liquid mixture primarily containing ammonia and hydrogen peroxide. A liquid containing ammonia is added to the liquid mixture to maintain the concentration of ammonia in the liquid mixture applied to the silicon substrate in the range between 2.5 wt. % and 3.5 wt. %. The liquid containing ammonia is added to the liquid mixture at a constant time interval. The constant time interval is set to be equal to a time period which is necessary for the concentration of ammonia in the liquid mixture to change from a first concentration level of no more than 3.5 wt. % to a second concentration level of no less than 2.5 wt. %, the second concentration level being lower than the first concentration level. The concentration of ammonia in the liquid containing ammonia and the amount thereof to be added to the liquid mixture are adjusted so as to increase the concentration of ammonia in the liquid mixture to the first concentration level by addition thereof.