High Quality Fine-Pitch Cu-Cu Wafer-on-Wafer Bonding with Optimized Ti Passivation at 160°C

In this paper, we investigate low temperature, low pressure and fine-pitch Copper-Copper thermo-compression bonding using an optimized Titanium (Ti) passivation layer. Ultra-thin Ti layer not only accomplishes the dual role of protecting surface of Cu from oxidation and reducing the effective surface roughness, but also allows the Cu to diffuse. The novelty of this surface passivation approach is the accomplishment of bonding at low temperature of 160° C and pressure to 3.5 KN. The lower bonding temperature and pressure exhibits a very good bond at the interface may give realistic chance to use 3D IC platform. Surface analysis of post patterned Cu/Ti pads were analyzed using X-Ray Photoelectron Spectroscopy (XPS) measurement of the surface corroborates proper passivation of Cu pads. The quality of bonded wafer was tested in Instron microtester measurement system. Also the morphology of bonded wafer was examined using Cross-sectional FE-SEM and Idonus Wafer Bonder IR Inspection (WBI) tool.

[1]  이화영.  X , 1960, Chinese Plants Names Index 2000-2009.

[2]  Dennis Sylvester,et al.  Analytical modeling and characterization of deep-submicrometer interconnect , 2001 .

[3]  Dorota Temple,et al.  Fabrication and characterization of metal-to-metal interconnect structures for 3-D integration , 2009 .

[4]  Arifur Rahman,et al.  System-level performance evaluation of three-dimensional integrated circuits , 2000, IEEE Trans. Very Large Scale Integr. Syst..

[5]  Chuan Seng Tan,et al.  Application of self assembly monolayer (SAM) in lowering the process temperature during Cu-Cu diffusion bonding of 3D IC , 2009, 2009 4th International Microsystems, Packaging, Assembly and Circuits Technology Conference.

[6]  A. Dutta,et al.  Room temperature desorption of Self Assembled Monolayer from Copper surface for low temperature & low pressure thermocompression bonding , 2015, 2015 IEEE 65th Electronic Components and Technology Conference (ECTC).

[7]  Kuan-Neng Chen,et al.  Microstructure examination of copper wafer bonding , 2001 .

[8]  Kuan-Neng Chen,et al.  Bonding parameters of blanket copper wafer bonding , 2006 .

[9]  Chuan Seng Tan,et al.  Cu-Cu diffusion bonding enhancement at low temperature by surface passivation using self-assembled monolayer of alkane-thiol , 2009 .

[10]  Börje Johansson,et al.  First-principles calculations of the vacancy formation energy in transition and noble metals , 1999 .

[11]  A. Fan,et al.  Copper Wafer Bonding , 1999 .

[12]  H. Y. Li,et al.  High density bump-less Cu-Cu bonding with enhanced quality achieved by pre-bonding temporary passivation for 3D wafer stacking , 2011, Proceedings of 2011 International Symposium on VLSI Technology, Systems and Applications.

[13]  Young-Bae Park,et al.  Effect of Wet Pretreatment on Interfacial Adhesion Energy of Cu-Cu Thermocompression Bond for 3D IC Packages , 2009 .

[14]  D. F. Lim,et al.  Cu passivation for enhanced low temperature (≤300°C) bonding in 3D integration , 2013 .

[15]  S. Singh,et al.  Low temperature, low pressure CMOS compatible Cu -Cu thermo-compression bonding with Ti passivation for 3D IC integration , 2015, 2015 IEEE 65th Electronic Components and Technology Conference (ECTC).

[16]  Ryutaro Maeda,et al.  Surface activated bonding of silicon wafers at room temperature , 1996 .

[17]  Miss A.O. Penney.  (b) , 1974, The New Yale Book of Quotations.

[18]  Tadatomo Suga,et al.  Room temperature Cu–Cu direct bonding using surface activated bonding method , 2003 .

[19]  Siva Rama Krishna Vanjari,et al.  Ultra-thin Ti passivation mediated breakthrough in high quality Cu-Cu bonding at low temperature and pressure , 2016 .

[20]  E. S. Machlin,et al.  An Introduction to Aspects of Thermodynamics and Kinetics: Relevant to Materials Science , 1991 .

[21]  Ching-Te Chuang,et al.  Novel Cu-to-Cu Bonding With Ti Passivation at 180 °C in 3-D Integration , 2013 .

[22]  Kuan-Neng Chen,et al.  Morphology and Bond Strength of Copper Wafer Bonding , 2004 .

[23]  D. F. Lim,et al.  Temporary passivation of Cu for low temperature (< 300°C) 3D wafer stacking , 2011, 2011 IEEE International Interconnect Technology Conference.

[24]  Ching-Te Chuang,et al.  Novel Cu-to-Cu Bonding With Ti Passivation at 180 $^{\circ}{\rm C}$ in 3-D Integration , 2013, IEEE Electron Device Letters.

[25]  Asudeb Dutta,et al.  Facile non thermal plasma based desorption of self assembled monolayers for achieving low temperature and low pressure Cu–Cu thermo-compression bonding , 2015 .

[26]  J. Torres,et al.  Electromigration resistance of copper interconnects , 1997 .

[27]  D. F. Lim,et al.  Enhancing Cu-Cu Diffusion Bonding at Low Temperature Via Application of Self-assembled Monolayer Passivation , 2011 .

[28]  Chuan Seng Tan,et al.  Achieving low temperature Cu to Cu diffusion bonding with self assembly monolayer (SAM) passivation , 2009, 2009 IEEE International Conference on 3D System Integration.

[29]  Chuan Seng Tan,et al.  Copper bonded layers analysis and effects of copper surface conditions on bonding quality for three-dimensional integration , 2005 .

[30]  Young-Bae Park,et al.  Effect of HF & H2SO4 pretreatment on interfacial adhesion energy of Cu-Cu direct bonds , 2012 .

[31]  P.C.H. Chan,et al.  Multiple layers of CMOS integrated circuits using recrystallized silicon film , 2001, IEEE Electron Device Letters.

[32]  C. S. Tan.  Application of self-assembled monolayer (SAM) in low temperature bump-less Cu-Cu bonding for advanced 3D IC , 2010, 2010 5th International Microsystems Packaging Assembly and Circuits Technology Conference.

[33]  E. Beyne,et al.  3D integration by Cu-Cu thermo-compression bonding of extremely thinned bulk-Si die containing 10 μm pitch through-Si vias , 2006, 2006 International Electron Devices Meeting.

[34]  Chuan Seng Tan,et al.  Effects of surface treatment on the bonding quality of wafer-level Cu-to-Cu thermo-compression bonding for 3D integration , 2013 .