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Influence of Bosch Etch Process on Electrical Isolation of TSV Structures
- Source :
- IEEE Transactions on Components, Packaging and Manufacturing Technology. 1:1497-1507
- Publication Year :
- 2011
- Publisher :
- Institute of Electrical and Electronics Engineers (IEEE), 2011.
-
Abstract
- Bosch process is widely used in the fabrication of through silicon via (TSV) holes for 3-D integrated circuit and 3-D Packaging applications mainly due to its high silicon etch rate and selectivity to mask. However, the adverse impact on the electrical performance of the TSV due to the sidewall scallops or wavy profile due to the cyclical nature of the Bosch process has not been thoroughly investigated. This paper therefore focuses on the impact of sidewall scallops on the inter-via electrical leakage performance. Based on finite element analysis, this paper describes that the high stress concentration on the dielectric and barrier layers at the sharp scallops can potentially contribute to barrier failure. It is demonstrated that by smoothening the sidewalls of the TSV, the thermo-mechanical stresses on the dielectric and tantalum barrier is significantly reduced. A test vehicle is designed and fabricated with different geometry of deep silicon vias to study the impact of sidewall profile smoothening for different copper diffusion barrier stacks. It is experimentally demonstrated that the inter-via electrical leakage current can be reduced by almost three orders of magnitude when the sidewall roughness is reduced or replaced by a smoother sidewall. It is also indicated that it is sufficient to smoothen the initial few micrometers of the TSV depth by using a non-Bosch etch process. It is concluded that the Bosch etch process can still be used, with all its merits of high etch rate and high etch selectivity, by tailoring a short initial etch step to smoothen the top sidewalls to minimize the adverse effects of the sidewall scallops.
- Subjects :
- Materials science
Fabrication
Diffusion barrier
Through-silicon via
Silicon
business.industry
chemistry.chemical_element
Integrated circuit
Dielectric
Industrial and Manufacturing Engineering
Electronic, Optical and Magnetic Materials
law.invention
chemistry
law
Electronic engineering
Deep reactive-ion etching
Optoelectronics
Electrical and Electronic Engineering
business
Leakage (electronics)
Subjects
Details
- ISSN :
- 21563985 and 21563950
- Volume :
- 1
- Database :
- OpenAIRE
- Journal :
- IEEE Transactions on Components, Packaging and Manufacturing Technology
- Accession number :
- edsair.doi...........5a7fce86a776b5b7ebd574e8747389f0