Zeolite Molecular Sieve Thin Films As Low-K Dielectrics
Tech ID: 10131 / UC Case 1999-179-0
The next generation of integrated circuits (ICs), with feature size smaller than 0.25 micron, will require inter-metal dielectrics with k less than 3. Current commercially available dielectric materials, such as spin-on glasses and fluorinated SiO2 (k>3) are inadequate. Organic polymers and inorganic nonporous silica have been investigated as potential alternative materials. However, both present several drawbacks. Although organic polymers can have a k between 2 and 3, they display low thermal stability and poor heat conductivity. In addition, the low mechanical strength of polymeric materials can lead to problems in the chemical and mechanical polishing (CMP) process. Generating porosity inside of inorganic materials, such as nanoporous silica, has proven to be a popular method for reducing the k of these materials. However, present formulations have only demonstrated a dielectric constant of approximately 2. Also, the extremely high porosity of nanoporous silica leads to poor heat conductivity, low mechanical strength, and low resistance to electrical breakdown. Further concerns with this material include the necessity of surface treatments to avoid moisture adsorption and its significant shrinkage during drying, which creates problems for metal gap filling.
Scientists at the University of California have developed an novel method for using zeolite molecular sieves and low-k dielectrics as well as techniques for the design and synthesis of thin films of these materials for use as inter-metal dielectrics in ICs.
The new UC technology provides the following benefits:
- Pure silica zeolites demonstrate higher chemical, thermal, and mechanical stability, and lower k than sol-gel silica and surfactant templated mesoporous silica;
- Hydrophobic properties help to mitigate water adsorption problems;
- Method is easily incorporated into existing semiconductor manufacturing processes;
- Allows production of zeolite films with designed properties.
|United States Of America||Issued Patent||6,573,131||06/03/2003||1999-179|