隨著高功率電子元件的發展，因應效能的提升勢必產生更多熱能，為了避免高溫對元件的可靠度及運作帶來影響，多晶氮化鋁因具有高熱導率、高絕緣性及低成本，適合作為高功率電子元件的散熱基板。然而，多晶氮化鋁基板在透過高溫燒結後會產生粗糙的表面，導致在後續的磊晶製程衍生出良率上的問題。因此本研究將探討化學機械拋光(Chemical Mechanical Polishing，CMP)於改善多晶氮化鋁的表面粗糙度。首先針對AlN的材料及組成進行分析，分析後的AlN表面粗糙度來到Sa約為400 nm，代表了化學機械拋光所需的製程時間較長。由於拋光液對化學機械拋光的表面粗糙度帶來很大的影響，因此使用拋光液對氮化鋁基板進行浸泡實驗，並透過重量損失、表面粗糙度、微觀結構分析，以得出適合AlN的拋光液及稀釋比例。實驗結果使用1:1稀釋比例的ESA 220拋光液，因具有最快的化學反應及在貼近製程的30分鐘浸泡時間下不會產生腐蝕，因此成為後續化學機械拋光時選用的實驗參數。接著為了進一步得到更好的表面粗糙度，透過改變下壓力、轉速及時間來探討參數對表面粗糙度之影響。由實驗結果，AlN的平坦化過程主要是從AlN最高的晶粒開始進行移除，且可將化學機械拋光分成兩個階段，在第一階段使用大的下壓力及轉速(P=8.67 psi、V=90 rpm)會得到較低的表面粗糙度，表面粗糙度達Sa=44.48 nm；而在第二階段使用大的下壓力及低的轉速(P=8.67 psi、V=30 rpm)時，表面粗糙度可降至Sa=23.51 nm，並透過拉長時間確定了該實驗參數的再現性。

With the development of high-power electronics, more heat energy is bound to be generated in response to the improvement of performance. In order to avoiding the influence of high temperature on the reliability and operation of components, polycrystalline aluminum nitride has high thermal conductivity, high insulation and low cost. It is suitable as a heat dissipation substrate for high-power electronic components. However, the polycrystalline aluminum nitride substrate will have a rough surface after being sintered at high temperature, which also result in yield problems in the subsequent epitaxial process. Therefore, this study will investigate the use of chemical mechanical polishing (CMP) to improve the surface roughness of polycrystalline aluminum nitride. Initially, the material and composition of AlN will be analyzed. The surface roughness of AlN is about Sa=400 nm, which means that the process time required for chemical mechanical polishing is relatively long. Then, since the slurry has a great influence on the surface roughness of chemical mechanical polishing, the aluminum nitride substrate was soaked in the slurry, and the weight loss, surface roughness, microstructure were analyzed to obtain the suitable AlN substrate of polishing solution and dilution ratio. The experimental results use ESA 220 polishing solution with a dilution ratio of 1:1, for it has the best chemical reaction rate and don`t cause corrosion under the 30-minute immersion time close to the process, so it becomes the experimental parameter for subsequent chemical mechanical polishing. Then, in order to further obtain better surface roughness, the influence of parameters on surface roughness was discussed by changing the down pressure, rotation speed and time. From the experimental results, the planarization process of AlN is mainly removed from the highest grains of AlN, and the chemical mechanical polishing can be divided into two stages. In First stage, by setting the parameter of P=8.67 psi and V=90 rpm will get lower surface roughness, for the surface roughness is Sa=44.48 nm. In second stage, by using high downforce and low rotational speed (P=8.67 psi, V=30 rpm), the surface roughness could be reduced to Sa = 23.51 nm, and the reproducibility of this experimental parameter was determined by elongation time.

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