Browsing by Author "Su, Jay"

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An RDL-First Fan-Out Panel-Level Package for Heterogeneous Integration Applications
(2019-01-01)
Lin, Yu-Min
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Wu, Sheng-Tsai
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Wang, Chun-Min
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Lee, Chia-Hsin
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Huang, Shin-Yi
Technologies of Fan-outpanel-level packaging (FOPLP) are studies in this paper. First, the warpage control of a molded panel is a crucial problem for FOWLP technology development. In this paper, finite element analysis (FEA) is applied to study the influence of back end of the line (BEOL) process-induced warpage, as well as characterization for simulation, and investigation of each single process. In our process, a liquid release material is coated onto a 370 mm x 470 mm glass carrier. After baking, three layers of redistribution layer (RDL), passivation, and Cu leads are fabricated on the panel with coating, exposing, developing, lithography, and electroplating processes. Silicon test chips with a size of 16 mm x 10 mm and micro solder bumps with a pitch of 90 mu m are thinned down to 150 mu m. Test chips are then flip-chip bonded onto glass carrier with pre-bond and reflow proces. After panel molding, a laser debonding method, another key technology advancement, is utilized for panel debond. Debond performance, which is directly related to laser parameter and panel-level package (PLP) structure, is critical. After debonding, the molded panel is cleaned, followed by dicing and OSP coating processes, and then the electrical performance of the interconnection is evaluated. Reliability tests at the component level, such as pre-condition, thermal cycling test (TCT), and unbiased HAST (uHAST), are performed. The demonstration of RDL-first PLP technology without interposers proves its great potential in heterogeneous integration applications.
An RDL-First Fan-out Wafer-level Package for Heterogeneous Integration Applications
(2018-01-01)
Lin, Yu-Min
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Wu, Sheng-Tsai
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Shen, Wen-Wei
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Huang, Shin-Yi
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Kuo, Tzu-Ying
Fan-out wafer-level packaging (FOWLP), a new heterogeneous integration technology, is gradually becoming an attractive solution. Compared with conventional 2.5D/3D IC structures, fan-out WLP does not use a costly interposer element and can have a thin, high-density, and low-cost IC packaging. In this study, a novel fan-out WLP with RDL-first method is demonstrated. Finite element method was used to optimize the warpage control of a reconstituted wafer and to identify the material properties and fabrication for the FOWLP. Calculation results were applied in the design of the test vehicle. Reliability testing of each component level was performed with different techniques such as temperature cycling test (TCT), high temperature storage (HTS) and thermal humidity storage test (THST). The demonstration of RDL-first WLP technology without interposer proves that it has excellent potential for heterogeneous integration applications.
Optimization of laser release process for throughput enhancement of fan-out wafer-level packaging
(2018-01-01)
Lee, Chia-Hsin
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Su, Jay
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Liu, Xiao
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Wu, Qi
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Lin, Jim-Wein
Fan-out wafer-level-packaging (FOWLP) technology has been developed with various advantages, such as smaller form factor, lower cost, and simplified supply chain for heterogeneous integration. There have been several process schemes like chip-first or chip-last FOWLP integration discussed widely in conferences in recent years. One process in all of these process schemes has in common is the use of a temporary carrier for subsequent redistribution layer (RDL) formation, chip stacking and molding processes. Although the separation of a temporary carrier from the reconstituted wafer could be achieved without significant hurdles, there were few studies addressing optimization of carrier separation for throughput enhancement. Thus, this paper is designed to address the needs in optimizing carrier separation process based upon laser ablation technology. Two phases of experiments were designed to select the appropriate laser release layer and define optimal laser settings. The first experiment was used to evaluate correlation of the laser absorption, laser energy, and spot pitch versus completeness of laser ablation. The second experiment included RDL-first FOWLP integration. At first, 300-mm glass carriers (1000 mu m thick) with coefficient of thermal expansion of 8 ppm/degrees C were treated by selected laser release layers. After deposition of 0.05-mu m Ti/0.15 mu m Cu on the glass carrier, passivation of around 8 mu m was coated and patterned by lithography for electroplating Cu interconnections with a density of approximately 10% of the surface area. Subsequently, die bonding, build-up layers, or molding compound were applied on top to form a 200-mu m reconstituted wafer. The reconstituted wafer was then separated from the glass carrier through a laser ablation process using a 355-nm laser to determine optimal throughput. Experiments to study correlation of laser release layer with laser settings along with a demonstration of full RDL-first FOWLP integration are discussed thoroughly to address the need of throughput enhancement, which could serve as cornerstone for realizing cost-effective RDL-first FOWLP.
Process Development and Material Characteristics of TSV-less Interconnection Technology for FOWLP
(2017-01-01)
Shen, Wen-Wei
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Lin, Yu-Min
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Chang, Hsiang-Hung
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Kuo, Tzu-Ying
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Fu, Huan-Chun
Fan-out wafer-level-packaging (FO-WLP) technology is developed with the advantages of smaller package size, higher Input/Output (I/O) counts, lower cost, and better performance. In this study, the FO-WLP technology is applied to TSV-less inter-connection technology of 2.5D IC packaging and a novel RDL-first wafer level packaging is demonstrated. Firstly, a pre-coated laser release layer at the interface of RDL and carrier wafer is used for the separation of the reconfigured wafer and carrier wafer with laser de-bonding technology. Since release layer material is the key factor for de-bonding, these materials are evaluated to determine the quality. Test chips are flip-chip bonded onto a carrier wafer with 2 layers of RDL and passivation, following by wafer molding process. Wafers reveal a warp surface due to chemical material shrinkage and CTE mismatch during post mold curing. Warpage of molded wafer is needed to be optimized for equipment handling and the warpage characterization is collected to analyze by different processes. To examine the quality of the structure, electrical measurement is carried out and their respective results are presented.
Ultrathin Glass Wafer Lamination and Laser Debonding to Enable Glass Interposer Fabrication
(2015)
Shen, Wen-Wei
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Chang, Hsiang-Hung
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Wang, Jen-Chun
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Ko, Cheng-Ta
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Tsai, Leon
Interposer fabrication processes are applied in three-dimensional (3-D) integrated circuit (IC) integration to shorten the interconnection among different stacked chips and substrates. Because Si is a common material in semiconductor technology, Si interposers have been widely studied in many research activities. Compared with a Si wafer, glass substrates have the advantages of high resistivity, low dielectric constant, low insertion loss, adjustable coefficient of thermal expansion (CTE), and the possibility to use panel-size substrates as well as thin glass substrates (100 mu m) to avoid the costly thinning process for realization of low-cost 2.5-D ICs. Thus, glass interposer fabrication is studied thoroughly in this paper. Thin glass wafers have reduced mechanical stiffness. Therefore, handling and shipping thin glass wafers (<= 100 mu m) throughout the semiconductor fabrication and packaging assembly processes are critical. Temporary wafer bonding technology is used in this study to bond a thin glass wafer to a carrier to improve the rigidity. Vacuum lamination technology is used in this study as a bonding process to enhance the cost-effectiveness. After processing, the carrier is removed by laser debonding. The thin glass wafer with structures on both sides does not need to undergo a glass thinning process and saves a lot of cost compared to the traditional glass or Si interposer processes. Thin 300-mm glass wafers 100 mu m thick are evaluated as: (a) blank thin glass wafers and (b) thin glass wafers with through-glass vias (TGVs) 30 mu m in diameter. A UV laser with a wavelength of 308 nm, which has the benefit of less impact to the device, was adopted to laser debonding. This method also has several benefits such as high throughput, low temperature, zero-force debonding, and possible selective laser debonding. Adhesive and release layers are key enabling materials for thin glass handling. In addition, the use of a laminator for temporary bonding and laser debonding are included in this study. Based on the excellent fabrication, the thin glass interposer has great potential to be applied in 2.5-D integration applications.