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:
Oct. 09, 1990
Filed:
Jan. 02, 1990
Meinhard Meyer, Munich, DE;
Oswald Stormer, Tuntenhausen, DE;
Messerschmitt-Bolkow-Blohm GmbH, Munich, DE;
Abstract
A method and apparatus for process control in both the production of uniform material layers using vapor deposition, sputtering, chemical deposition, etc. and the treating of material layers. In particular, the process and apparatus are particularly useful in semiconductor fabrication where ion implantation or diffusion is used. A brief test signal of preset shape, frequency spectrum, or frequency sequence is applied at given time intervals to the material layer whose production characteristics need to be monitored. The measuring signal is applied to a digital evaluation circuit in a process control computer. The signal has various components whose time constants and/or conductivities are different from one another and which together are characteristics of the current flowing through the layer being monitored. In particular, the current flowing over the surface layer i.sub.1, the current flowing through particle houndary areas i.sub.3, and the current through homogeneous material ranges i.sub.2 can be distinguished from one another. The results from the measuring signal can be compared to stored reference values for the layer. Discrepancies between the actual and desired values are measured and used to adjust the process in a known fashion.