Development of low dielectric constant alumina-based ceramics for microelectronic substrates

Thesis/Dissertation · Sat May 01 04:00:00 EDT 1993

DOI:https://doi.org/10.2172/10150031· OSTI ID:10150031

Wu, Shun Jackson ^[1]

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1. Univ. of California, Berkeley, CA (United States)

The performance of high speed computers depends not only on IC chips, but also on the signal propagation speed between these chips. The signal propagation delay in a computer is determined by the dielectric constant of the substrate material to which the IC chips are attached. In this study, a ceramic substrate with a low dielectric constant (k ≈ 5.0) has been developed. When compared with the traditional alumina substrate (k ≈ 10.0), the new material corresponds to a 37% decrease in the signal propagation delay. Glass hollow spheres are used to introduce porosity (k = 1.0) to the alumina matrix in a controlled manner. A surface coating technique via heterogeneous nucleation in aqueous solution has been used to improve the high temperature stability of these spheres. After sintering at 1,400 C, isolated spherical pores are uniformly distributed in the almost fully dense alumina matrix; negligible amounts of matrix defects can be seen. All pores are isolated from each other. Detailed analyses of the chemical composition find that the sintered sample consists of α-alumina, mullite and residual glass. Mullite is the chemical reaction product of alumina and the glass spheres. Residual glass exists because current firing conditions do not complete the mullitization reaction. The dielectric constant of the sintered sample is measured and then compared with the predicted value using Maxwell`s model. Mechanical strength is evaluated by a four-point bending test. Although the flexural strength decreases exponentially with porosity, samples with 34% porosity (k ≈ 5.0) still maintain adequate mechanical strength for the proper operation of a microelectronic substrate.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10150031
• Report Number(s): LBL--32657; ON: DE94011360
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360200
42 ENGINEERING
426000
ALUMINIUM OXIDES
CALCINATION
CERAMICS, CERMETS, AND REFRACTORIES
COMPARATIVE EVALUATIONS
COMPONENTS
ELECTRON DEVICES AND CIRCUITS
DIELECTRIC PROPERTIES
EXPERIMENTAL DATA
FLEXURAL STRENGTH
GLASS
INTEGRATED CIRCUITS
MICROSTRUCTURE
MULLITE
POROSITY
POROUS MATERIALS
RESEARCH PROGRAMS
SLIP CASTING
SUBSTRATES
SURFACE COATING
THERMAL CONDUCTIVITY