Warpage Modeling and Characterization to Simulate the Fabrication Process of Wafer-Level Adhesive Bonding

Lim, Ji-Hyuk; Ham, Sunny; Jeong, Byung-Gil

doi:10.1109/iemt.2007.4417081

Cited by 5 publications

(5 citation statements)

References 4 publications

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“…The bowing of the c-Si solar cells is caused by the c-Si wafer, front/back electrodes, and ARC. The stress of the film is represented by and the whole stress is expressed by the intrinsic stress (σ ) and thermo-mechanical stress (σ ) as in Equation (1) [18][19][20][21] :…”

Section: Theoretical Analysis Of Bowing Phenomenon Of C-si Solar Cellsmentioning

confidence: 99%

Analysis of the Bowing Phenomenon for Thin c-Si Solar Cells using Partially Processed c-Si Solar Cells

et al. 2019

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The silicon wafers for solar cells on which the paste is deposited experience a bowing phenomenon. The thickness of commonly used c-Si wafers is 180 μm or more. When fabricating c-Si solar cells with this wafer thickness, the bowing value is 3 mm or less and the problem does not occur. However, for the thin c-Si solar cells which are being studied recently, the output reduction due to failure during manufacture and cracking are attributed to bowing. In generally, it is known that the bowing phenomenon arises mainly from the paste applied to the back side electrode of c-Si solar cells and the effects of SiNx (silicon nitride) and the paste on the front side are not considered significant. The bowing phenomenon is caused by a difference in the coefficient of expansion between heterogeneous materials, there is the effect of bowing on the front electrode and ARC. In this paper, a partially processed c-Si solar cell was fabricated and a bowing phenomenon variation according to the wafer thicknesses was confirmed. As a result of the experiment, the measured bow value after the firing process suggests that the paste on the front-side indicates a direction different from that of the back-side paste. The bow value increases when Al paste is deposited on SiNx. The fabricated c-Si solar cell was analyzed on basis of the correlation between the bowing phenomenon of the materials and the c-Si wafer using Stoney’s equation, which is capable of analyzing the relationship between bowing and stress. As a result, the bowing phenomenon of the c-Si solar cell estimated through the experiment that the back side electrode is the important element, but also the front electrode and ARC influence the bowing phenomenon when fabricating c-Si solar cells using thin c-Si wafers.

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Section: Theoretical Analysis Of Bowing Phenomenon Of C-si Solar Cellsmentioning

confidence: 99%

Analysis of the Bowing Phenomenon for Thin c-Si Solar Cells using Partially Processed c-Si Solar Cells

et al. 2019

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“…Now finite element method has been generally used in thermo-mechanical reliability analysis for a series of WLP warpage, such as TSV wafer warpage [6], wafer warpage resulting from curing of underfill glue [7], warpage of WL-CSP [8], etc. Lim et al used "cut/paste" calculating technology to test and verify the warpage of the bonded wafer with the structure of "glass/polymer/Si" [9]. However, there is lack of wafer level modeling and simulation studies for WLP of MEMS with glass frit bonding.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, warpage issues involved not only that of single IC wafer but also that of both front-end and back-end of the wafer process even WLP system. For example, the warpage of image sensor WLP (the cover glass wafer and silicon wafer were bonded by means of the organic film) was studied [4]. wafer warpage from back-end process was predicted and verified [5].…”

Section: Introductionmentioning

confidence: 99%

Warpage characteristics of wafer-level package of MEMS with glass frit bonding

Wang

Zhu

et al. 2013

2013 14th International Conference on Electronic Packaging Technology

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Warpage is one of the challenging problems for wafer level package (WLP). Especially, the bonding process of multiple wafers will bring additional stress to WLP and warpage of WLP. This paper aims at the stress and warpage characteristics of the WLP (consisting of silicon cover wafer and silicon MEMS wafer) with glass frit bonding. The finite element (FE) method and MOS (Multi-beam Optical Sensor) technology were used. Simulation result indicated that WLP presents almost zero warpage. MOS measurement result indicated that WLP actually presents convex warpage instead of zero warpage. It turned out that the convex warpage results from the temperature difference between WLP wafers (i.e. cover wafer and MEMS wafers) in the course of post-bond cooling. Taken the temperature difference into account, the simulation result was consistent with experiment results. Furthermore, on the basis of the convex warpage value the stress of WLP was also calculated so as to understand the stress distribution and estimate the reliability level of the MEMS device. Keywords-warpage,wafer level package(WLP), finite element method(FEM), micro Electro mechanical systems(MEMS), multibeam optical sensor (MOS)

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“…In fact, warpage issues involved not only that of single IC wafer but also multiple wafers with bonding [6] [7]. However, the key technology for package of multiple wafers is matter-of-course bonding, Therefore the issue of wafer bonding is also important for warpage study of WLP.…”

Section: Introductionmentioning

confidence: 99%

“…Of course the stress distribution in WLP can not obtain by means of warpage measurement. On the other hand, FEM has been generally used in thermo-mechanical reliability analysis for a series of WLP warpage [9][10][11][12]. Therefore, in this work, the FE method was used to study the warpage and stress for optimal design towards the reliability of the Si-Si bonding WLP.…”

Section: Introductionmentioning

confidence: 99%

Warpage and stress optimization of wafer-level package of MEMS with glass frit bonding

Zhu

et al. 2014

2014 15th International Conference on Electronic Packaging Technology

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Warpage issue of wafer level package (WLP) has caught the attention of WLP industry. This paper aims at the warpage characteristics and optimization of the WLP (consisting of silicon MEMS wafer and silicon cover wafer) with glass frit bonding. Finite-element method (FEM) was used to study the warpage and stress optimization of the Si-Si bonding WLP. Some factors which affect WLP warpage, such as CTE (coefficient of thermal expansion) and Young's modulus of glass frit, ring thickness & width of glass frit and bonding temperature etc. were optimized. The stress of WLP was also calculated and the reliability level of the MEMS device was estimated. It turned out that CTE and Young modulus of glass frit are the key parameters for decreasing WLP warpage and stress and promoting the MEMS WLP. Ring width of glass frit and the thickness of silicon cover plate wafer have little impacts on WLP stress and warpage. With the optimized parameters taken into account, the stress in MEMS WLP falls down. Those optimization results have been put into actual WLP manufacture. Keywords-warpage; stress; optimization; glass frit; wafer level package (WLP); finite-element method (FEM); MOS (multi-beam optical sensor) deformation measurement; micro electro mechanical systems (MEMS)

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Warpage Modeling and Characterization to Simulate the Fabrication Process of Wafer-Level Adhesive Bonding

Cited by 5 publications

References 4 publications

Analysis of the Bowing Phenomenon for Thin c-Si Solar Cells using Partially Processed c-Si Solar Cells

Analysis of the Bowing Phenomenon for Thin c-Si Solar Cells using Partially Processed c-Si Solar Cells

Warpage characteristics of wafer-level package of MEMS with glass frit bonding

Warpage and stress optimization of wafer-level package of MEMS with glass frit bonding

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