Development of the nitride film thickness standard (NFTS)

Prabha Durga Pal

doi:10.1117/12.316460

6 July 1998 Development of the nitride film thickness standard (NFTS)

Prabha Durga Pal

Proceedings Volume 3479, Laser Interferometry IX: Applications; (1998) https://doi.org/10.1117/12.316460
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1998, San Diego, CA, United States

Abstract

The semiconductor industry has been demanding film thickness reference material for films other than thermally grown silicon dioxide for sometime. To meet this challenge, Nitride Film Thickness Standard (NFTS) has been developed in four nominal thickness values, 20.0 nm, 90.0 nm, 120.0 nm and 200.0 nm. These are silicon nitride (Si₃N₄) films on silicon crystal substrate. Work is underway to develop a 9.0 nm standard. Thin nitride films are particularly needed for calibration of the thickness of nitride layers in capacitors and isolation masks for LOCOS (local oxidation of silicon). The reference material is certified for derived film thickness. The study consists of measurements made on four different sets of wafers that included patterned and unpatterned wafers. The measurements made on these wafer sets were used for answering issues related to film stability and cleaning. The stability study includes the search for a cleaning process that will restore a prior surface condition. On two sets of wafers two different types of cleaning procedures were used. Results indicate that a sulfuric acidmegasonic clean will etch the nitride film while an isopropyl alcohol clean followed by a deionized water rinse can be used over and over again. The third set of wafers was never cleaned and measurements were made on these over a period of two years. The last set of wafers is patterned. These are cleaned prior to measurement. Results show that LPCVD silicon nitride films are stable and can be used with confidence over a long period of time for calibrating optical metrology instruments.

Citation Download Citation

Prabha Durga Pal "Development of the nitride film thickness standard (NFTS)", Proc. SPIE 3479, Laser Interferometry IX: Applications, (6 July 1998); https://doi.org/10.1117/12.316460

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
11 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Silicon

Semiconducting wafers

Silicon films

Standards development

Refractive index

Dielectrics

Thin films

Show All Keywords

Keywords/Phrases

Search In:

Publication Years