The following operators can be used to better focus your queries.
( ) , AND, OR, NOT, W/#
? single char wildcard, not at start
* multi char wildcard, not at start
(Cat? OR feline) AND NOT dog?
Cat? W/5 behavior
(Cat? OR feline) AND traits
Cat AND charact*
This guide provides a more detailed description of the syntax that is supported along with examples.
This search box also supports the look-up of an IP.com Digital Signature (also referred to as Fingerprint); enter the 72-, 48-, or 32-character code to retrieve details of the associated file or submission.
Concept Search - What can I type?
For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.
Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.
The use of a mask to avoid unwanted reflections from reaching the photodiode in an endpoint detection system results in improved accuracy and reliability of the system.
English (United States)
This text was extracted from a PDF file.
100% of the total text.
Page 1 of 1
Photodiode Mask for Endpoint Detection System
The use of a mask to avoid unwanted reflections from reaching the
photodiode in an endpoint detection system results in improved accuracy and
reliability of the system.
In the processing of semiconductor wafers, accurate determination of the
etch endpoint is critical to insure product quality. A visually aligned endpoint
detection system used on reactive ion etching tools employs a laser to generate
a beam which is reflected off the wafer being etched. The reflected beam is
detected by a photodiode. An endpoint signal results from the interference of the
reflected laser beam from the wafer surface and the interface of a thin film on the
wafer as it is being etched.
The reflected laser beam passes through several lenses and beam splitters
before reaching the photodiode. The lenses and beam splitters cause unwanted
reflections which cause the output of the photodiode to be erratic and often
prevents accurate detection of the etch endpoint.
A mask consisting of a stainless steel disk with about a 60 mil hole is
mounted in front of the photodiode. The main reflected laser beam is aligned to
pass through the hole. This arrangement prevents the unwanted reflections from
reaching the photodiode, resulting in a well-defined endpoint.