背晶金屬化矽晶片與DBC陶瓷基板固晶接合研究

Abstract

在功率元件與模組晶片與產品尺寸持續縮小化，卻同時需要具備高效能、低功耗的趨勢下，先進封裝技術的研究成為最有潛力的研究領域，然而先進封裝技術的發展受限於接合介面的介金屬化合物成長、熱影響、可靠度、電性等...相關的問題，使得在近年來BGBM(Backside Grinding & Backside Metallization)製程晶片與固液擴散接合 (SLID)引起了學術界與產業界的極大興趣，主要是因為在接合領域可以達到「低溫接合，高溫應用」的效果，能夠作為一種可靠的接合方法。

本研究在真空環境中通過 SLID 技術將以130℃蒸鍍優化的 BGBM wafer (Si/Ti/Ni/Ag/Sn，厚度分別為1, 3, 5, 14 KÅ)於DBC基板(Au/Pd/Ni/Cu/Al2O3，厚度分別為1, 0.75, 45, 750 KÅ)上接合，通過 SEM/EDX 觀察接合界面處的擴散現象，接合系統實現了具有超過 7.91 MPa 優異的平均接合強度且定義明確的層狀結合結構，觀察到Ag3Sn、Ni3Sn4和Ni3Sn2的介金屬化合物在 Si/Ti/Ni/Ag/Sn 晶片和 DBC 基板的接合界面之間，證明了SLID 接合系統是一項非常有利被應用於低溫接合中的材料，這項創新的接合技術在功率元件與模組、IGBT、微機電產業(MEMS)、光電產業、傳感器、對熱敏感之元件、3D IC以及各個領域的互聯應用顯示出巨大的潛力。

由於更低溫度的接合與實現更高的可靠度有利於技術的發展與提升產業利用性，因此將擴散焊接溫度進一步降低到 250°C，這將有利於更低的製程溫度與更低元件耐熱需求，有降低成本的優勢，完成接合的樣品投入嚴謹的可靠度驗證(高溫貯存試驗 High Temperature Storage Test 125°C、高溫水蒸汽壓力試驗Pressure Cook Test 121°C/100%R.H./2atm、溫度循環試驗Temperature Cycling Test -55°C - 125°C 溫變率大於20℃/min以上)後，藉以研究對接合處微結構演變的影響，通過 SEM/EDX 觀察分析接合界面處的介金屬化合物變化狀況，驗證了接合的可靠性。

此外本研究透過BGBM Si/Ti/Ni/Sn 與BGBM Si/Ti/Ni/Ag/Sn金屬化矽晶片與Ni/Pd/Au表面處理的DBC氧化鋁基板通過固液擴散接合，驗證在接合中間層加入Ag層所形成的Ag3Sn介金屬化合物夾層，可以有效防止接合介面處出現的孔洞和縫隙，在 Si/Ti/Ni/Ag/Sn 晶片和 DBC 襯底之間的接合界面上確定的介金屬化合物的相為Ag3Sn、Ni3Sn4 和 Ni3Sn2，推力測試的平均接合強度約為 19.75 MPa，最大接合強度達到 35.24 MPa。

考慮降低材料成本的可能性，採用BGBM Si/Ti/Ni/Cu/Sn 與Si/Ti/Ni/Cu/Ag/Sn DBC金屬化矽晶片與Ni/Pd/Au表面處理的DBC氧化鋁基板通過固液擴散接合進行探討。

本研究也加入了奈米銀燒接合技術試驗做相關系列的接合研究與探討，期望在學術界與產業界的能夠有進一步的貢獻。

Under the trend that the size of power components and module chips and products continues to shrink, but at the same time need to have high performance and low power consumption, the research of advanced packaging technology has become the most potential research field, but the development of advanced packaging technology is limited Problems related to the growth of intermetallic compounds at the bonding interface, thermal influence, reliability, electrical properties, etc. have made BGBM (Backside Grinding & Backside Metallization) process wafers and solid-liquid diffusion bonding (SLID) aroused academic circles in recent years. The great interest in the industry is mainly because the effect of "low-temperature bonding, high-temperature application" can be achieved in the field of bonding, and it can be used as a reliable bonding method.

In this study, optimized BGBM wafers (Si/Ti/Ni/Ag/Sn, with thicknesses of 1, 3, 5, and 14 KÅ) were deposited on DBC substrates (Au/Pd/ Ni/Cu/Al2O3 with thicknesses of 1, 0.75, 45, 750 KÅ) were bonded, and the diffusion phenomenon at the bonding interface was observed by SEM/EDX. The bonding system achieved an excellent average bonding strength of more than 7.91 MPa and a well-defined The layered bonding structure, intermetallic compounds of Ag3Sn, Ni3Sn4 and Ni3Sn2 were observed between the bonding interface of Si/Ti/Ni/Ag/Sn wafer and DBC substrate, proving that the SLID bonding system is a very favorable method to be applied at low-temperature Materials in bonding, this innovative bonding technology has shown great promise in power components and modules, IGBTs, MEMS, optoelectronics, sensors, heat-sensitive components, 3D ICs, and interconnection applications in potential various fields. Since lower temperature bonding and higher reliability are conducive to the development of technology and the improvement of industrial applicability, the diffusion soldering temperature is further reduced to 250°C, which will benefit lower process temperature and lower heat resistance of components demand, has the advantage of reducing costs, and the completed joint samples are put into rigorous reliability verification (high-temperature storage test 125°C, high-temperature water vapor pressure test Pressure Cook Test 121°C/100%R.H./2atm, temperature cycle After testing the Temperature Cycling Test -55°C - 125°C (temperature change rate greater than 20°C/min), it is used to study the influence on the microstructure evolution of the joint, and the change of the intermetallic compound at the joint interface is observed and analyzed by SEM/EDX, the reliability of the bonding was verified.

In addition, this study uses solid-liquid diffusion bonding of BGBM Si/Ti/Ni/Sn and BGBM Si/Ti/Ni/Ag/Sn metalized silicon wafers and Ni/Pd/Au surface-treated DBC alumina substrates to verify that in the middle of bonding The Ag3Sn intermetallic compound interlayer formed by adding the Ag layer can effectively prevent holes and gaps at the joint interface, and the intermetallic determined on the joint interface between the Si/Ti/Ni/Ag/Sn wafer and the DBC substrate The phases of the compound are Ag3Sn, Ni3Sn4, and Ni3Sn2, the average joint strength of the thrust test is about 19.75 MPa, and the maximum joint strength reaches 35.24 MPa.

Considering the possibility of reducing the cost of materials, BGBM Si/Ti/Ni/Cu/Sn and Si/Ti/Ni/Cu/Ag/Sn DBC metalized silicon wafers and DBC alumina substrates with Ni/Pd/Au surface treatment were adopted Solid-liquid diffusion bonding. This study also joined the nano-silver firing bonding technology experiment to do a series of bonding research and discussion, hoping to make further contributions in academia and industry.