Determination of silicon in thin-film aluminum on a silicon substrate

Journal Article · Mon Sep 01 00:00:00 EDT 1980 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac50061a063· OSTI ID:5077227

Tallant, D R

One aspect of microelectronics fabrication technology involves metallization of integrated circuits with a thin layer (1 ..mu..m) of aluminum containing a small amount of silicon, which helps prevent diffusion of the aluminum into the substrate. Quality control of the metallization process necessitated development of a technique for the determination of silicon (0 to 3 wt %) in a thin aluminum layer on a silicon substrate. Emphasis was therefore placed on developing a wet chemical technique by which the thin aluminum films could be selectively etched without sampling the silicon substrate and by which the 5 to 150 ..mu..g of solubilized silicon could be reliably determined. By depositing a thin coating of silicon nitride on the silicon substrate prior to the deposition of the silicon-containing aluminum film, a chemically-resistant (i.e., passive) substrate was formed from which the aluminum layer could be selectively etched. The aluminum film is then etched with sodium hydroxide. In the silicon determination procedure the etched solution is first acidified with hydrochloric acid, and ammonium molybdate solution is added to form silicomolybdic acid H/sub 4/SiO/sub 4/(MoO/sub 3/)/sub 12/, which is extracted into 1-butanol. The organic phase is then analyzed for the 12 molybdate atoms associated with each silicon atom by flame atomic absorption spectrometry. Over a hundred samples were analyzed for silicon by the above procedure and the silicon content was found to range from 8 ..mu..g to 130 ..mu..g.

• Research Organization: Sandia National Labs., Albuquerque, NM
• DOE Contract Number: AC04-76-DP00789
• OSTI ID: 5077227
• Journal Information: Anal. Chem.; (United States), Vol. 52:11
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM
CHEMICAL ANALYSIS
SILICON
ABSORPTION SPECTROSCOPY
AMMONIUM COMPOUNDS
BUTANOLS
ETCHING
FILMS
MOLYBDATES
QUANTITATIVE CHEMICAL ANALYSIS
SILICON COMPOUNDS
SODIUM HYDROXIDES
SOLVENT EXTRACTION
ALCOHOLS
ALKALI METAL COMPOUNDS
ELEMENTS
EXTRACTION
HYDROGEN COMPOUNDS
HYDROXIDES
HYDROXY COMPOUNDS
METALS
MOLYBDENUM COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SEMIMETALS
SEPARATION PROCESSES
SODIUM COMPOUNDS
SPECTROSCOPY
SURFACE FINISHING
TRANSITION ELEMENT COMPOUNDS
400104* - Spectral Procedures- (-1987)