Highly beneficial organic liner with extremely low Thermal stress for fine Cu-TSV in 3D-integration
Highly beneficial organic liner with extremely low Thermal stress for fine Cu-TSV in 3D-integration
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DOI：
10.1109/iedm.2014.7047054
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发表时间：
2014-12
期刊：
影响因子：
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通讯作者：
M. Murugesan;T. Fukushima;J. Bea;Y. Sato;H. Hashimoto;K. Lee;M. Koyanagi
中科院分区：
文献类型：
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作者：
M. Murugesan;T. Fukushima;J. Bea;Y. Sato;H. Hashimoto;K. Lee;M. Koyanagi
研究了热化学气相沉积（CVD）有机聚酰亚胺（PI）衬垫在直径或宽度（φ）从3 μm到30 μm的Cu-TSV中的热稳定性、漏电流（LC）、电容、TSV链电阻、应力吸收能力以及热机械应力（TMS）引起的Si晶格畸变等方面的作用。CVD沉积PI衬垫的测量LC值为10-13至10-15 A的量级，这与常规SiO2衬垫获得的值相当。PI内衬极低的模量值不仅有助于减少Cu挤出量，而且还保持均匀的Cu挤出。我们能够实现PI衬垫的保形沉积，即使在φ = 3 μm的通孔具有10的深宽比，在TSV底角处的台阶覆盖值大于0.8（80%）。发现具有PI衬里的TSV的d-空间变化并且因此晶格应力（~200 MPa）比具有SiO2衬里的TSV的d-空间变化（~1000 MPa）小近五倍。在400 °C下退火之前和之后拍摄的C1 s、O 1 s和N1s芯级X射线光电子能谱证实PI衬垫的降解几乎为零。采用500 nm厚的PI衬底，在12英寸硅片上实现了每10 μ m宽度TSV的低电阻值为18 mΩ。
The constructive role played by the Thermal-chemical vapor deposited (CVD) organic polyimide (PI) liner in the Cu-TSVs with diameter or width (φ) varying from 3 μm to 30 μm has been studied meticulously for its thermal stability, leakage current (LC), capacitance, TSV-chain resistance, stress absorbing ability, and the Si-lattice distortion arising from thermo-mechanical stress (TMS). The measured LC values for the CVD deposited PI liner is in the order of 10-13 to 10-15 A, which is on par with the value obtained for the conventional SiO2 liner. The extremely low modulus value of PI liner helps not only to reduce the amount of Cu extrusion, but also maintain an uniform Cu-extrusion. We were able to achieve a conformal deposition of PI liner even in φ = 3 μm via having the aspect ratio of 10 with the step coverage values of more than 0.8 (80%) at the TSV bottom corner. It was found that the d-space changing and thus the lattice stress is nearly five times smaller for the TSV with PI liner (~200 MPa) than for the TSV with SiO2 liner (~1000 MPa). Nearly zero-degradation of PI liner was confirmed from C1s, O1s, and N1s core-level x-ray photoelectron spectra taken before and after annealing at 400 °C. We obtained the resistance value of as low as 18 mΩ per 10 μm-width TSV with 500 nm-thick PI liner fabricated on 12-inch wafer.