Assuring ultra-clean environments in microsystem packages : irreversible and reversible getters.

Zifer, Thomas ; Whinnery, LeRoy L., Jr. ; Hollenshead, Jeromy Todd ; Buffleben, George M. ; McElhanon, James Ross ; Nilson, Robert H.

Sandia National Laboratories

关键词: Materials Testing;    Getters;    Surface Area;    Absorption;    36 Materials Science;   

DOI  :  10.2172/918394
RP-ID  :  SAND2003-8784
RP-ID  :  AC04-94AL85000
RP-ID  :  918394

美国|英语

来源: UNT Digital Library

【 摘 要 】

A new generation of irreversible, chemically reacting getters specifically targeted toward assuring the integrity of the local environment within microsystem packages were developed and evaluated. These reactive getters incorporate volatile species into a polymer through covalent bonds, thus producing a non-volatile product. These reactive getters will be combined with getters that rely on absorption media (e.g. zeolites and high surface area carbon fibers) to scavenge non-reactive species, like solvents. Our getter systems will rely on device packaging to limit exchange between the microsystem and the global environment. Thus, the internal getters need only provide local environmental control within the microsystem package. A series of experiments were conducted to determine uptake rates and capacities absorption and reactive-based getters. Diffusion rates through the binder used to hold the getter particles together were also investigated. Getters were evaluated in environments with a saturated headspace and with a limited amount of the volatile species of interest. One- and two-dimensional numerical models and analysis techniques have been developed and used to predict the transport of contaminant species within a representative microsystem package consisting of an open gas-filled volume adjacent to a polymer layer containing embedded particles of getter. The two-dimensional model features explicit representation of the individual getter particles while the one-dimensional treatment assumes a homogeneous distribution of getter material within the getterlpolymer layer. Example calculations illustrate the dependence of getter performance on reaction rates, polymer diffusivity, and getter particle volume fraction. In addition, the model is used to deduce surface reaction rates, solid phase diffusivities, and maximum-loading densities by least-squares fitting of model predictions to measured histories of gas-phase contaminant concentration and getter weight gain.