鎳矽反應性多層膜中矽化鎳形成的控制及自蔓延反應的特性

Abstract

反應性多層膜由交替排列的奈米級放熱材料組成，能在局部能量激發後以光和熱的形式釋放儲存的能量。本研究聚焦於1:1原子比例的鎳矽多層膜，探討雙層總數、粗糙度和基板對自蔓延反應和產物相的影響。利用磁控濺鍍在-20 ℃環境下製備鎳矽多層膜，雙層厚度分別固定為50 nm、65 nm和170 nm，並透過紅外線雷射激發與高速攝影機觀察到兩階段的自蔓延波前。固定雙層厚度下增加雙層數量，將減少輻射熱損失並提升自蔓延速度。對於獨立式多層膜，FR4基板的表面起伏導致激發前多層膜的粗糙度上升，相較於製備在矽基板上的平坦多層膜，其自蔓延速度較慢。透過去除光阻層和增加FR4表面起伏，成功實現了雙層厚度50 nm、總厚度3.34 μm的多層膜在FR4基板上的自蔓延反應。爆炸性矽化反應的產物相取決於雙層厚度和多層膜的整體組成。在超薄雙層厚度下，最終產物相受介面處的非晶態Ni-Si固溶體組成主導；50 nm雙層厚度有利於單相NiSi2形成，而65 nm雙層厚度則有利於θ-Ni2Si。在較厚雙層厚度下，如170 nm，有利於形成多層膜整體組成的平衡相，通過精確控制Si原子比例達到50 at.%，促進了單相NiSi的生成。

Reactive multilayers (RMLs) are alternating nanoscale exothermic materials that release stored energy upon localized energy ignition. This study investigated the effects of the number of bilayers, roughness, and substrate on self-propagating reactions and product phases in equiatomic Ni/Si RMLs. The Ni/Si RMLs, either freestanding or on FR4 substrates, were fabricated with bilayer thicknesses of 50 nm, 65 nm, and 170 nm by magnetron sputtering at -20 ℃. Using infrared laser ignition and a high-speed camera, two-step self-propagation wavefronts were observed. With a fixed bilayer thickness, increasing the number of bilayers reduced radiative heat loss and enhanced self-propagation velocity. Surface undulations on FR4 substrates caused rough freestanding RMLs to have slower self-propagation velocities than flat freestanding RMLs. RMLs with a 50 nm bilayer and a total thickness of 3.34 μm enabled successful self-propagating reactions on FR4 substrates. The product phase of the explosive silicidation reaction in Ni/Si RMLs depended on the bilayer thickness and overall composition of the multilayers. In ultra-thin bilayers, the final product phase was determined by the composition of the amorphous Ni-Si solid solution at the interface. Experimental results indicated that a bilayer thickness of 50 nm favored the formation of single-phase NiSi2, while increasing the bilayer thickness to 65 nm favored the formation of θ-Ni2Si. In thicker bilayers, the equilibrium phase corresponding to the overall composition of the multilayers was favored, specifically NiSi in this study. In RMLs with a bilayer thickness of 170 nm, precisely controlling the Si atomic ratio to 50 at.% facilitated the formation of single-phase NiSi.