A fracture model for exfoliation of thin silicon films
- 91 Downloads
The direct exfoliation of thin films from silicon wafers has the potential to significantly lower the cost of flexible electronics while leveraging the performance benefits and established infrastructure of traditional wafer-based fabrication processes. However, controlling the thickness and uniformity of exfoliated silicon thin films has proven difficult due to a lack of understanding and control over the exfoliation process. This paper presents a new silicon exfoliation process and model which enables accurate prediction of the thickness and quality of the exfoliated thin-film based on the exfoliation process parameters. This model uses a parametric, finite element, linear elastic fracture mechanics study with nonlinear loading to determine how each process parameter affects the crack propagation depth. A metamodel is then constructed from the results of numerous simulations to inform the design and operation of a novel exfoliation tool and predict thickness of produced films. In order to manufacture uniform, high-quality films, the tool creates a controlled peeling load that is able to propagate a crack through the silicon in a controlled manner. Finally, exfoliated silicon samples produced with the prototype tool are evaluated and compared to metamodel projections, confirming the ability of the tool to steer crack trajectory within ± 3 microns of the crack depth predictions.
KeywordsExfoliation Single crystal silicon Finite element analysis Spalling
The authors acknowledge and thank Miaomiao Yang for her experience, effort, insight, and support in accomplishing this work. The authors thank Kirsten Cole Christopherson for her effort in completing these experiments. The authors would also like to thank Liam Conolly, Dipankar Behera, and Cheng Zhao for the informative discussions and technical expertise. This work is based upon work supported primarily by the National Science Foundation under Cooperative Agreement No. EEC-1160494. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
- Calvez D, Roqueta F, Jacques S, Bechou L, Ousten Y, Ducret S (2014) Crack propagation modeling in silicon: a comprehensive thermomechanical finite-element model approach for power devices. IEEE Trans Compon Packag Manuf Technol 4(2):360–366. https://doi.org/10.1109/TCPMT.2013.2293094 CrossRefGoogle Scholar
- Cannon RM, Fisher RM, Evans AG (1985) Decohesion of thin films from ceramic substrates. In: MRS proceedings, vol 54. https://doi.org/10.1557/PROC-54-799
- Janssen G, Abdalla M, van Keulen F, Pujada B, van Venrooy B (2009) Celebrating the 100th anniversary of the Stoney equation for film stress: developments from polycrystalline steel strips to single crystal silicon wafers. Thin Solid Films 517(6):1858–1867. https://doi.org/10.1016/j.tsf.2008.07.014 CrossRefGoogle Scholar
- Mathew L, Jawarani D (2010) Method of forming an electronic device using a separation-enhancing species. US patent US7749884B2. https://patents.google.com/patent/US7749884/en
- Pudasaini PR, Sharma M, Ruiz-Zepeda F, Ayon AA (2014) Ultrathin, flexible, hybrid solar cells in sub-ten micrometers single crystal silicon membrane. In: 2014 IEEE 40th photovoltaic specialist conference (PVSC). IEEE, pp 0953–0955Google Scholar
- Rao RA, Mathew L, Saha S, Smith S, Sarkar D, Garcia R, Stout R, Gurmu A, Onyegam E, Ahn D (2011) A novel low cost 25\(\mu \)m thin exfoliated monocrystalline si solar cell technology. In: 2011 37th IEEE photovoltaic specialists conference (PVSC). IEEE, pp 001504–001507Google Scholar
- Shahrjerdi D, Bedell SW, Khakifirooz A, Fogel K, Lauro P, Cheng K, Ott JA, Gaynes M, Sadana DK (2012) Advanced flexible CMOS integrated circuits on plastic enabled by controlled spalling technology. In: 2012 IEEE international electron devices meeting (IEDM). IEEE, pp 5–1Google Scholar
- Takei K, Takahashi T, Ho JC, Ko H, Gillies AG, Leu PW, Fearing RS, Javey A (2010) Nanowire active-matrix circuitry for low-voltage macroscale artificial skin. Nat Mater 9:821–826. https://doi.org/10.1038/nmat2835
- Tanielian M, Lajos RE, Blackstone S (1986) Method of making thin free standing single crystal films US patent US4582559A. https://patents.google.com/patent/US4582559A/en?oq=+4%2c582%2c559
- Weil R (1970) The origins of stress in electrodeposits. Part 1. Plating 57(12):1231–1237Google Scholar