Temporary Bonding and Debonding Technologies to Enable Innovative Fan-Out Embedded Interposer for High-Density Applications

2015 ◽  
Vol 2015 (1) ◽  
pp. 1-6
Author(s):  
Alvin Lee ◽  
Jay Su ◽  
Xiao Liu ◽  
Yin-Po Hung ◽  
Yu-Min Lin ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
High Speed ◽  
Process Integration ◽  
Dielectric Material ◽  
Wafer Level ◽  
Additive Process ◽  
Bonding Material ◽  
Wafer Level Packaging ◽  
Ic Packaging ◽  
Temporary Bonding

As requirements increase for mobile devices to be lighter and thinner and to operate at high speed and high bandwidth, innovations in wafer-level packaging have evolved to 3-D structures, such as package-on-package (PoP), fan-out integration, and through-silicon-via (TSV) interposer architectures. However, wafer-level packaging is still considered to be costly and slow in throughput due to wafer size limitations. In this study, temporary bonding and debonding processes using mechanical or laser release technologies were applied in the fabrication process of an integrated embedded glass interposer as a foundation for 3-D integrated circuit (IC) packaging on panel-level packaging. Glass interposers having dimensions of 10 mm × 10 mm and a thickness of 120 μm were fabricated. The interposers had through-glass vias (TGVs) 25 μm in diameter and 3000 I/O pads of copper under-bump metallization (UBM) and were designed as a nearly full-array type. The interposers were supported by a temporary bonding material on silicon or glass wafers and embedded by built-up dielectric material on which fan-out redistribution circuit layers were deposited. For forming the pattern of the redistribution layer, a UV laser was used to form 75-μm-diameter blind vias, and conductive interconnections were made by a semi-additive process (SAP) using photolithography and electrolytic copper. The process of building up layers from the glass interposer to form an embedded fan-out interposer can eliminate a joining process required by traditional 2.5-D IC integration. Finally, the embedded fan-out carrier is separated from the glass or silicon wafer through a laser debonding process. An experiment to study the correlation of bonding material and release material with built-up lamination in backside processes will be discussed in this paper to address full process integration on panel-size substrates. The combination of temporary bonding technology with mechanical or laser release technologies will pave the way for realizing cost-effective 3-D IC packaging on panel-level substrates.

Advances in Temporary Bonding and Debonding Technologies for use with Wafer-Level System-in-Package (WLSiP) and Fan-Out Wafer-Level Packaging (FOWLP) Processes

2018 ◽  
Vol 2018 (1) ◽  
pp. 000051-000056 ◽  
Author(s):  
Michelle Fowler ◽  
John P. Massey ◽  
Matthew Koch ◽  
Kevin Edwards ◽  
Tanja Braun ◽  
...  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Active Area ◽  
Vertical Deformation ◽  
Level System ◽  
Wafer Level ◽  
Molding Process ◽  
Bonding Material ◽  
Wafer Level Packaging ◽  
Temporary Bonding ◽  
Mechanical Release

Abstract Today's complex fan-out wafer-level packaging (FOWLP) processes include the use of redistribution layers (RDL) and reconstituted wafers with epoxy mold compound (EMC) for use in heterogeneous integration [1]. Wafer-level system-in-package (WLSiP) uses fan-out wafer-level packaging (FOWLP) to build the system-in-package (SiP) by attaching know-good die (KGD) in a chip-first process to a tape laminated temporary carrier. If the dies are attached in a die-up configuration (active area facing up) and then over-molded with EMC, contact pads on the embedded die are exposed during the backside grind process. During the RDL build, the temporary carrier supplies mechanical support for the thinned substrate. In a die-down configuration with the active area facing down (eWLB), the temporary carrier is removed after the molding process thus exposing the contact pads for RDL build and solder ball mount. The ideal chip attachment scheme should minimize lateral movement of the die during over-mold (die shift) and also minimize vertical deformation of the bonding material. Thermal release tape provides a convenient way to attach die to a carrier prior to over-molding with EMC. However, not all bonding materials are suitable for presentation in tape form, so the material used in the tape may not be the optimal choice. An alternative method is to directly apply temporary bonding material to the carrier substrate. This enables the use of bonding materials with higher melt viscosity and improved thermal stability, resulting in less vertical deformation during die placement, and reduced die shift during over-molding. The bonding material will ideally have high adhesion to the EMC wafer to prevent delamination in the bond line during downstream processing. Stack stress and warpage is a major concern which causes handling and alignment problems during processing. The bonding material and carrier will need to be specifically suited to minimize the effects of stress in the compound wafer. Such material must balance rigidity with warp to prevent lateral die shift and deformation induced by coefficient of thermal expansion (CTE) mismatch between the carrier and EMC material [2]. Bonding materials must also have enough adhesion to the EMC material to overcome such stress without bond failure for an associated debond path (such as laser or mechanical release). In this experiment, we will examine a thermoplastic bonding material in combination with different release materials, addressing die shift, and deformation after EMC processing. Successful pairs will then undergo carrier release using either mechanical release or laser ablation release technology.

Embedded Si Fan Out: A Low Cost Wafer Level Packaging Technology Without Molding and De-bonding Processes

2017 ◽  
Vol 2017 (DPC) ◽  
pp. 1-15
Author(s):  
Hong Xie ◽  
Daquan Yu ◽  
Zhenrui Huang ◽  
Zhiyi Xiao ◽  
Li Yang ◽  
...  
Keyword(s):  
Form Factor ◽  
High Speed ◽  
Low Cost ◽  
High Density ◽  
Wafer Level ◽  
Small Form ◽  
Wafer Level Packaging ◽  
Temporary Bonding ◽  
Small Form Factor ◽  
Si Wafer

The growing and diversifying system requirements have continued to drive the development of a variety of new package technologies and configurations: small form factor, low weight, low profile, high pin count and high speed and low cost. Embedded chip in EMC, also called fan-out wafer-level packaging (FOWLP), has been used in various products such as baseband, RF (radio frequency) transceiver, and PMICs (power management ICs). Currently, INFO technology developed by TSMC®, NANIUM® were in mass production for 3D integration for processor and memory, which inspires other packaging foundries to develop their own embedded FOWLP for the forecasted explosive growth of this market in the next few years. There are a number of challenges for FOWLP. For process point of view, temporary bonding and de-bonding are required. EMC wafers are difficult to handle due to its large warpage driven by the big CTE difference between the Si and molding material. In addition, the manufacturing of fine pitch RDL on EMC surface is also difficult. In this paper, the concept of wafer level embedded Si Fan-Out (eSiFO) technology was introduced and the development progress was reported. For eSiFO, cavities with certain depth were formed by Si dry etch. Then device dies were thinned to designed thickness. The dice were then placed into the cavities and bonded by the attached film on the bottom of the dice. A reconstructed wafer was formed. The micro gap between the chip and sidewall of the cavity as well as the surface of the reconstructed wafer were filled by dry film using vacuum process. Next, the pads were opened, followed RDL fabrication, repassivation, BGA, wafer thinning and dicing. Finally, an eSiFO package was fabricated. There are a number of advantages for eSiFO technology. There is nearly no warpage since the Si was used as reconstruct substrate. The process is relatively simple since no molding, temporary bonding and de-bonding are required. RDL manufacturing is easier on Si wafer vs with molding compounds and can achieve high density routing. Furthermore, it can provide small form factor since the thinning of wafer is the last step. To prove the concept of eSiFO, a 3.3 x 3.3mm package with 50 BGA bumps at 400μm pitch was fabricated. The device wafer was thinned to 100μm. The die size is 1.96 × 2.36mm with pad pitch at about 90μm. The depth of the cavities on 8 in. wafer formed by Bosch process on bare Si wafer was 107μm with 8μm variation. The length and width of Si cavities is 20μm larger than die size. In the package, there is one layer Cu RDL with thickness of 3μm, minimum line width of 13.72μm. The BGA ball diameter is 280μm. All the processes were evaluated and the results showed such packages can be produced. Reliability tests including THS, T/C, HTS and HAST were carried out and no failure issue was observed. Mechanical simulation was used to analyze the stress distribution during TC test and the results showed the maximum stress was located at the RDL near the UBM. In summary, a low cost wafer level fan out technology using reconstructed Si wafer was developed. The process is simple without molding, temporary bonding and de-bonding. The reliability tests of test vehicles proved that such package is reliable. The newly developed eSiFO technology can be widely used for chips requiring fan-Out, small form factor and high density interconnects.

Optimization of laser release layer, glass carrier, and organic build-up layer to enable RDL-first fan-out wafer-level packaging

2016 ◽  
Vol 2016 (1) ◽  
pp. 000190-000195 ◽  
Author(s):  
Alvin Lee ◽  
Jay Su ◽  
Baron Huang ◽  
Ram Trichur ◽  
Dongshun Bai ◽  
...  
Keyword(s):  
High Speed ◽  
Process Integration ◽  
Cost Effective ◽  
Wafer Level ◽  
Molding Compound ◽  
Fine Line ◽  
Glass Substrates ◽  
Laser Ablation Process ◽  
Wafer Level Packaging ◽  
Increasing Demand

Abstract With increasing demand for mobile devices to be lighter and thinner and consume less power while operating at high speed and high bandwidth, many equipment suppliers and assembly participants have invested great efforts to achieve fine-line fan-out wafer-level packaging (FOWLP). However, the inherent warp of reconstituted wafers, which can contribute to poor die placement accuracy and/or delamination at the interface of the build-up layer and carrier, remains a major challenge. In this study, the interactions among laser release layer, glass carrier, and build-up layer were evaluated for optimization of redistribution layer (RDL)–first FOWLP as a foundation to move toward fine-line FOWLP. In this study, a series of experiments incorporating glass carrier, laser release layer, and build-up layers were carried out to determine the optimal setup for RDL-first FOWLP. First, glass carriers (300 mm × 300 mm × 0.7 mm) with coefficients of thermal expansion of 3 and 8 ppm/°C were treated with 150-nm laser release layers. After deposition of 0.1 μm of sacrificial material on the glass carrier, 8-μm build-up layers were coated and patterned by lithography to electroplate Cu interconnections with a density of approximately 10% of the surface area. Subsequent to die attachment, molding compound was applied on top to form a 200-μm protective overcoat. The reconstituted wafer was then separated from the glass carrier through a laser ablation process using a 308-nm laser to complete the design of experiments (DOE). An experiment to study the correlation of glass carrier, laser release layer, build-up layers, and molding compound in RDL-first FOWLP processes is discussed to address full process integration on 300-mm glass substrates. The combination of glass carrier, laser release layer, build-up layer, and molding compound will pave the way for realizing cost-effective RDL-first FOWLP on panel-size substrates.

Residual Stress in Silicon Caused by Cu-Sn Wafer-Level Packaging

2013 ◽  
Author(s):  
Maaike M. V. Taklo ◽  
Astrid-Sofie Vardøy ◽  
Ingrid De Wolf ◽  
Veerle Simons ◽  
H. J. van de Wiel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Integrated Circuit ◽  
High Performance ◽  
White Light Interferometry ◽  
Wafer Level ◽  
Noticeable Effect ◽  
Micro Raman Spectroscopy ◽  
Wafer Level Packaging ◽  
Mems Device ◽  
Specific Technology

The level of stress in silicon as a result of applying Cu-Sn SLID wafer level bonding to hermetically encapsulate a high-performance infrared bolometer device was studied. Transistors are present in the read out integrated circuit (ROIC) of the device and some are located below the bond frame. Test vehicles were assembled using Cu-Sn SLID bonding and micro-Raman spectroscopy was applied on cross sectioned samples to measure stress in the silicon near the bond frame. The test vehicles contained cavities and the bulging of the structures was studied using white light interferometry. The test vehicles were thermally stressed to study possible effects of the treatments on the level of stress in the silicon. Finite element modeling was performed to support the understanding of the various observations. The measurements indicated levels of stress in the silicon that can affect transistors in regions up to 15 μm below the bond frame. The observed levels of stress corresponded well with the performed modeling. However, no noticeable effect was found for the ROIC used in this work. The specific technology used for the fabrication of the ROIC of a MEMS device is thus decisive. The level of stress did not appear to change as a result of the imposed thermal stress. The level of stress caused by the bond frame can be expected to stay constant throughout the lifetime of a device.

Damascene-Patterned Metal-Adhesive (Cu-BCB) Redistribution Layers

2006 ◽  
Vol 970 ◽  
Author(s):  
Ronald J. Gutmann ◽  
J. Jay McMahon ◽  
Jian-Qiang Lu
Keyword(s):  
Bonding Strength ◽  
Adhesive Bonding ◽  
Process Integration ◽  
Three Dimensional ◽  
Adhesive Layer ◽  
Wafer Level ◽  
Technology Platform ◽  
Metal Bonding ◽  
Wafer Level Packaging ◽  
Metal Metal

ABSTRACTA monolithic, wafer-level three-dimensional (3D) technology platform is described that is compatible with next-generation wafer level packaging (WLP) processes. The platform combines the advantages of both (1) high bonding strength and adaptability to IC wafer topography variations with spin-on dielectric adhesive bonding and (2) process integration and via-area advantages of metal-metal bonding. A copper-benzocyclobutene (Cu-BCB) process is described that incorporates single-level damascene-patterned Cu vias with partially-cured BCB as the bonding adhesive layer. A demonstration vehicle consisting of a two-wafer stack of 2-4 μm diameter vias has shown the bondability of both Cu-to-Cu and BCB-to-BCB. Planarization conditions to achieve BCB-BCB bonding with low-resistance Cu-Cu contacts have been examined, with wafer-scale planarization requirements compared to other 3D platforms. Concerns about stress induced at the tantalum (Ta) liner-to-BCB interface resulting in partial delamination are discussed. While across-wafer uniformity has not been demonstrated, the viability of this WLP-compatible 3D platform has been shown.

SiP(System in Package) Solutions with Wafer Level Packaging Technology

2011 ◽  
Vol 2011 (DPC) ◽  
pp. 002226-002253 ◽  
Author(s):  
In Soo Kang ◽  
Jong Heon (Jay) Kim
Keyword(s):  
Embedded System ◽  
High Performance ◽  
Low Cost ◽  
Wafer Level ◽  
Molding Compound ◽  
Wafer Level Packaging ◽  
Ic Packaging ◽  
Chip Size ◽  
Bonding Technology ◽  
Small Form Factor

In mobile application, the WLP technology has been developing to make whole package size almost same as chip size. However, the I/O per chip unit area has increased so that it gets difficult to realize ideal pad pitch for better reliability. Recently, to achieve the thin and small size, high performance and low cost semiconductor package, Embedding Die and Fanout Technologies have been suggested and developed based on wafer level processing. In this work, as a solution of system in package, wafer level embedded package and fanout technology will be reviewed. Firstly, Wafer level embedded System in Package (WL-eSiP) which has daughter chip (small chip) embedded inside mother chip (bigger chip) without any special substrate has been suggested and developed. To realize wafer level embedded system in package (WL-eSiP), wafer level based new processes like wafer level molding for underfilling and encapsulation by molding compound without any special substrate have been applied and developed, including high aspect ratio Cu bumping, mold thinning and chip-to-wafer flipchip bonding. Secondly, Fan-out Package is considered as alternative package structure which means merged package structure of WLCSP (wafer level chip size package) and PCB process. We can make IC packaging widen area for SIP(System in Package) or 3D package. In addition, TSV and IPD are key enabling technology to meet market demands because TSV interconnection can provide wider bandwidth and high transmission speed due to vertical one compared to wire bonding technology and IPD can provide higher performance, more area saving to be assembled and small form factor compared to discrete passive components.

Investigation of Wafer Level Packaging schemes for 3D RF interposer multi-chip module

2017 ◽  
Vol 2017 (1) ◽  
pp. 000258-000262
Author(s):  
Bart Vereecke ◽  
Philippe Soussan ◽  
Jian Zhu
Keyword(s):  
Integrated Circuit ◽  
Silicon Substrates ◽  
Wafer Level ◽  
Process Technology ◽  
Low Loss ◽  
Yield Optimization ◽  
Active Devices ◽  
Wafer Level Packaging ◽  
Rf Performance ◽  
Rf Loss

Abstract Very small RF modules can be realized through heterogenous integration of GaAs MMIC (monolithic microwave integrated circuit) onto a low loss Si sub-mount, with high density routing lines realized by advanced patterning. In this paper we investigate how to integrate MMIC active devices on GaAs with the RF passives produced on an interposer, using Si wafer process technology. High resistive Silicon substrates are required to minimize RF losses. The interposer is thinned below 100 μm to reveal Cu TSVs from the back of the interposer, while the front side is covered entirely with a silicon capping wafer for shielding the device. We compare different wafer level packaging approaches for producing the low RF-loss interposers, and populating them using die-to-die (D2D) or die-to-wafer (D2W) bonding of the MMIC components, followed by wafer level encapsulation. Two D2W approaches are compared, in the first approach the D2W mounting and the encapsulation happens before the Si interposer is thinned for TSV reveal. To avoid damage during thinning of the wafer, thicker substrates with deeper TSV of 150 μm or more are required. In a second approach, the thinning of the interposer is done prior to the mounting. Initial electrical data showed that the approach yielded proper RF performance, but further yield optimization is required.

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