Shin Eun Gu, Rehman Atteq ur, Lee Sang Hee, Lee Soo Hong
J Nanosci Nanotechnol. 2015 Oct;15(10):7823-7. doi: 10.1166/jnn.2015.11184.
The adhesion of the front electrodes to silicon substrate is the most important parameters to be optimized. Nickel silicide which is formed by sintering process using a silicon substrate improves the mechanical and electrical properties as well as act as diffusion barrier for copper. In this experiment p-type mono-crystalline czochralski (CZ) silicon wafers having resistivity of 1.5 Ω·cm were used to study one step and two step nickel electroless plating process. POCl3 diffusion process was performed to form the emitter with the sheet resistance of 70 ohm/sq. The Six, layer was set down as an antireflection coating (ARC) layer at emitter surface by plasma enhanced chemical vapor deposition (PECVD) process. Laser ablation process was used to open SiNx passivation layer locally for the formation of the front electrodes. Nickel was deposited by electroless plating process by one step and two step nickel electroless deposition process. The two step nickel plating was performed by applying a second nickel deposition step subsequent to the first sintering process. Furthermore, the adhesion analysis for both one step and two steps process was conducted using peel force tester (universal testing machine, H5KT) after depositing Cu contact by light induced plating (LIP).
前电极与硅衬底的附着力是需要优化的最重要参数。通过使用硅衬底的烧结工艺形成的硅化镍改善了机械和电学性能，同时还充当了铜的扩散阻挡层。在本实验中，使用电阻率为1.5Ω·cm的p型单晶硅（CZ）晶圆来研究一步和两步化学镀镍工艺。进行POCl3扩散工艺以形成方阻为70Ω/sq的发射极。通过等离子体增强化学气相沉积（PECVD）工艺在发射极表面沉积SiNx层作为减反射涂层（ARC）。使用激光烧蚀工艺局部打开SiNx钝化层以形成前电极。通过一步和两步化学镀镍工艺进行化学镀镍沉积。两步镀镍是在第一次烧结工艺之后进行第二次镍沉积步骤。此外，在通过光诱导电镀（LIP）沉积铜接触之后，使用剥离力测试仪（万能试验机，H5KT）对一步和两步工艺进行附着力分析。
