Sol-Gel Processing of Low Dielectric Constant Nanoporous Silica Thin Films
Abstract
Tetramethyl ammonium silicate (TMAS) is known as a structuring agent in zeolite synthesis. We report its first use to prepare porous silica films for low k dielectric applications in microelectronics. A solution of TMAS 18.7 wt.% was spin coated on silicon substrates with a 3000 A thick thermal oxide. The spin coated films were subsequently heat-treated at 450 deg C to obtain porous silica. The use of TMAS solution without gelation led to films of only moderate porosity value of 10%. The addition of methyl lactate, a gelling agent, significantly increased film porosity and improved the pore size distribution. For example, 50% porosity and uniform pore size distribution (average pore size ^ 40 A) has been achieved. Dielectric constants (k) of our porous films are as low as 2.5.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2001
- Accession Number
- ADP012194
Entities
People
- David W. Johnson Jr.
- Deok-yang Kim
- Henry Du
- Suhas Bhandarkar