Wafer-Level 3D Integration for ULSI Interconnects

2009 ◽  
pp. 79-90
Author(s):  
Ronald J. Gutmann ◽  
Jian-Qiang Lu
Keyword(s):  
Wafer Level ◽  
3D Integration

Direct bonding for wafer level 3D integration

2010 ◽  
Author(s):  
Lea Di Cioccio ◽  
Ionut Radu ◽  
Pierric Gueguen ◽  
Mariam Sadaka
Keyword(s):  
Wafer Level ◽  
3D Integration

Temporary and permanent bonding enables 3D integration of ultrathin wafers

2019 ◽  
Vol 2019 (DPC) ◽  
pp. 001118-001144
Author(s):  
Elisabeth Brandl ◽  
Thomas Uhrmann ◽  
Mariana Pires ◽  
Stefan Jung ◽  
Jürgen Burggraf ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
Bonding Process ◽  
Total Thickness ◽  
Wafer Level ◽  
3D Integration ◽  
Process Flow ◽  
Wafer Thickness ◽  
Temporary Bonding ◽  
Carrier Wafer ◽  
On Chip

Rising demand in memory is just one example how 3D integration is still gaining momentum. Not only the form factor but also performance is improved for several 3D integration applications by reducing the wafer thickness. Two competing process flows using thin wafers are to carry out for 3D integration today. Firstly, two wafers can be bonded face-to-face with subsequent thinning without the need to handle a thin wafer. However, some chip designs require a face-to-back stacking of thin wafers, where temporary bonding becomes an inevitable process step. In this case, the challenge of the temporary bonding process is different to traditional stacking on chip level, where usually the wafers are diced after debonding and then stacked on chip level, which means die thicknesses are typically in the range of 50 μm. The goal of wafer level transfer is a massive reduction of the wafer thickness. Therefore temporary and permanent bonding has to be combined to enable stacking on wafer level with very thin wafers. The first step is temporary bonding of the device wafer with the temporary carrier through an adhesive interlayer, followed by thinning and other backside processes. Afterwards the thinned wafer is permanently bonded to the target wafer before debonding from the carrier wafer. This can be repeated several times to be suitable for example a high bandwidth memory, where several layers of DRAM are stacked on top of each other. Another application is the memory integration on processors, or die segmentation processes. The temporary bonding process flow has to be very well controlled in terms of total thickness variations (TTV) of the intermediate adhesive between device and carrier wafer. The requirements for the temporary bonding adhesive include offering sufficient adhesion between device and carrier wafer for the subsequent processes. The choice of the material class for this study is the Brewer Science dual layer material comprising of a curable layer which offers high mechanical stability to enable low TTV during the thinning process and a release layer for mechanical debond process. The release layer must lead to a successful debond but prevent spontaneous debonding during grinding and other processes. Total thickness variation values of the adhesive will be analyzed in dependence of the adhesive layer thickness as this is a key criterion for a successful implementation at the manufactures. Besides the TTV the mechanical stability during grinding will be evaluated by CSAM to make sure no delamination has happened. For feasibility of the total process flow it is important that the mechanical debonding requires less force compared to the separation of the permanent bonded wafers. Other process parameters such as edge trimming of the device wafer as well as edge removal of the mechanical debond release layer are investigated.

The European 3D Heterogeneous Integration Platform (e-BRAINS) - a Particular Focus on Reliability and Low-Temperature Processes for 3D Integrated Sensor Systems

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001847-001884
Author(s):  
Peter Ramm ◽  
Armin Klumpp ◽  
Alan Mathewson ◽  
Kafil M. Razeeb ◽  
Reinhard Pufall
Keyword(s):  
Low Temperature ◽  
Heterogeneous Integration ◽  
Sensor Systems ◽  
Wafer Level ◽  
3D Integration ◽  
Integrated Sensor ◽  
Integration Platform ◽  
Ultrasonic Agitation ◽  
Bonding Technology ◽  
Low Temperature Bonding

The European 3D heterogeneous integration platform has been established by the consortium of the Integrated Project e-BRAINS [1], where technologies of the following relevant main categories of 3D integration are provided to enable future applications of smart sensor systems:3D System-on-Chip Integration - 3D-SOC: TSV technology for stacking of thinned devices or large IC blocks (global level),3D Wafer-Level-Packaging - 3D-WLP: embedding technology with through-polymer vias (TPV) for stacking of thinned ICs on wafer-level (no TSV), and3D System-in-Package - 3D-SIP: 3D stacking of packaged devices or substrates *definitions according to [2] Regarding TSV performance, the applications do not need ultra-high vertical interconnect densities as for 3D stacked Integrated Circuits – 3D-SIC*. Nevertheless, the lateral sizes of the TSVs are preferably minimized to allow for place and route for small “open” IC areas. Smaller TSVs are also preferred in order to reduce thermo-mechanical stress. e-BRAINS' focus is on how heterogeneous integration and sensor device technologies can be combined to bring new performance levels to targeted applications with high market potentials. The consortium, under coordination of Infineon and technical management by Fraunhofer EMFT, is composed of major European system manufacturers (Infineon, Siemens, SensoNor, 3D PLUS, Vermon and IQE), SMEs (DMCE, Magna Diagnostics, SORIN and eesy-ID), the large research institutions CEA Grenoble, Fraunhofer (EMFT Munich & IIS-EAS Dresden), imec, SINTEF, Tyndall and ITE Warsaw, and universities (EPFL Lausanne, TU Chemnitz and TU Graz). Target applications include automotive, ambient living and medical devices, with a specific focus on wireless sensor systems. Concerning the enabling 3D Heterogeneous Integration Platform, the e-BRAINS partners are working close together, where Infineon, Fraunhofer EMFT, imec and SINTEF are focusing mainly on 3D-SOC and 3D-WLP, and the French system manufacturer 3D PLUS and Tyndall on 3D-WLP and 3D-SIP technologies. The focus of this paper is on low-temperature bonding processes for highly reliable 3D integrated sensor systems. One of the key issues for heterogeneous systems production is the impact of 3D processes to the reliability of the product, i.e. the high built-in stresses caused by e.g. the CTE mismatch of complex layer structures (thin Si, ILDs, metals etc.) in combination with elevated bonding temperatures. As consequence, extensive project work was dedicated in the developments of reliable low-temperature bonding processes. Mainly intermetallic compound (IMC) bonding with Cu/Sn metal systems supported by ultrasonic agitation (Fraunhofer EMFT) was successfully introduced in 3D integration technology (see Fig. 2). A copper/tin solid-liquid interdiffusion (SLID) system was investigated using ultrasonic agitation to reduce the assembly temperature below the melting point of tin. Cleaning procedures are important shortly before joining the samples; dry cleaning has best results due to removal of thin oxide layers. Figure 2 shows a cross section of US supported Cu/Sn bonding at 150C. The intermetallic compounds Cu3Sn and Cu6Sn5 as well as pure tin easily can be identified. Due to low temperature assembly the most stable intermetallic compound (IMC) Cu3Sn has a minor share of the metal system. Most importantly there is no gap between top and bottom part of the joint despite the macroscopic assembly temperature is far away from the melting point of tin. But maybe the ultrasonic agitation brings enough energy to the interfaces, so locally melting can occur. In this way robust IMC bonding technology at 150C could be demonstrated with shear forces of 17 MPa and an alignment accuracy of 3 μm, well-suited for 3D integration. Figure 2: Low-temperature IMC bonding technology using ultrasonic agitation (Fraunhofer EMFT) Reliability for SLID contacts is certainly a very challenging objective especially looking for robust solutions in automotive applications. Thermally induced mechanical stress is the main reason for early fails during temperature cycling. Cross sectioned samples were investigated and methods like nanoindentation, Raman spectroscopy, fibDAC, and high local resolution x-ray scattering were applied to measure the intrinsic stresses. It can be shown that low temperature bonding is the right approach to avoid excessive stress cracking the interface or even fracturing the silicon. Also fatigue of metals can be reduced in a range that plastic deformation is no lifetime limiting factor.

On the Origins, Status, and Future of Flip Chip & Wafer Level Packaging

2010 ◽  
Vol 2010 (1) ◽  
pp. 000325-000332 ◽  
Author(s):  
Alan Huffman ◽  
Philip Garrou
Keyword(s):  
Technological Change ◽  
Flip Chip ◽  
Emerging Technologies ◽  
Unit Area ◽  
Form Factors ◽  
Electrical Performance ◽  
Wafer Level ◽  
3D Integration ◽  
Wafer Level Packaging ◽  
Area Array

As IC scaling continues to shrink transistors, the increased number of circuits per chip requires more I/O per unit area (Rent's rule). High I/O count, the need for smaller form factors and the need for better electrical performance drove the technological change towards die being interconnected (assembled) by area array techniques. This review will examine this evolution from die wire bonded on lead frames to flip chip die in wafer level or area array packages and discuss emerging technologies such as copper pillar bumps, fan out packaging, integrated passives, and 3D integration..

Vertical Integration: A Confederacy of Alignment, Bonding, and Materials Technologies

2006 ◽  
Vol 970 ◽  
Author(s):  
Shari Farrens
Keyword(s):  
Error Analysis ◽  
Vertical Integration ◽  
Lower Cost ◽  
Wafer Level ◽  
3D Integration ◽  
Integrated Manufacturing ◽  
Lower Power ◽  
3D Structures ◽  
Pros And Cons ◽  
Cmos Ic

ABSTRACTVertical or 3D integration is taking hold in both the CMOS IC industry and the MEMS industry. The need for smaller devices, lower power, increased functionality, and lower cost are driving the market toward chip and wafer level stacking. Equipment suppliers have been faced with numerous challenges to meet the demands of these emerging bonding applications. This paper will discuss the confederacy of alignment, bonding and materials unions that can lead to successful outcomes in integrated manufacturing.1. Alignment strategies for 3D integration: IR, BSA, and ISA as they pertain to specific bond methods2. Pros and Cons of 3D Bonding Techniques (Direct bonds, metal, adhesive, and eutectic)3. Error analysis in alignment of 3D structures

Bonding technologies for chip level and wafer level 3D integration

2014 ◽  
Author(s):  
Katsuyuki Sakuma ◽  
Spyridon Skordas ◽  
Jeffrey Zitz ◽  
Eric Perfecto ◽  
William Guthrie ◽  
...  
Keyword(s):  
Wafer Level ◽  
3D Integration
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