Fractal analysis of inorganic thin solid films with network structures

具有网络结构的无机固体薄膜的分形分析

• 批准号: 08650037
• 负责人: KUSANO Eiji
• 金额: $ 1.47万
• 依托单位: Kanazawa Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650037/
• 关键词: Thin Films; Sputtering; Titanium; Aluminum; Fractal; Island structure; Network Structure; フラクタル

I.Experimental procedure-Formation of Al/Ti Multilayr-The fractal island or network structure was deposited by dc magnetron sputtering. The cathodes used in the experiment were two 75mm diameter magnetrons equipped in an ultra high vacuum chamber pumped by a turbo molecular pump. Target materials were Al (99.99%) and Ti (99.98%). Substrates used were aluminobolosilicate glass. The discharge gas was Ar (99.9999%). Subatrate temperature was varied from 200C to 600C.In order to accelerate the formation of island structure of Al thin films, a Ti underlayr was deposited first on to the substrate, and then an Al layr was deposited sequentially on the Ti layr without breaking the vacuum. (The oxidation of the Ti surface deteriorated the formation of isolated Al island structures.) The thickness of the Ti underlayr was 500nm throughout all of the deposition, and that of the Al layr was changed from 10nm to 80nm.The surface morphology of the deposited films was analyzed by atomic force scanning … More probe microscope (AFM,Topo-Metrix : Type TMX-2000). The scan renge was 10mum squared with 300x300 digits. Fractal dimension of island or network dimension was obtained by a lake filling method from the digitized AFM data. Surface roughness, bearing ratio, average diameter of islands, and surface coverage were also obtained from the digitized AFM data.II.Experimental results-Surface morphology and Fractal dimension-It was found by AFM that isolated island structures with island's diameters ranging from about 0.5 to about 1mum were obtained for Al average thickness values of 20 to 40nm deposited at 550C.The large diameters of each island were the feature of the Al/Ti bilayr island stucture. For a further increase in the substrate temperature, the island shape form convex in the its center, then formed a network-like structure. The determination of fractal dimensions were tried for both island and network structure. The fractal dimension was well obtained for an island stucture, while it was not for a network shape by applying the lake filling method because of the complexity of the network shape.For the island structures, fractal dimensions of about 2.0 to 2.2 were obtained. The fractal dimensions of about 2.0 point that the island-structure-like film growth for these Al thickness values was two-dimensional growth where the fractal dimension was almost equal to the Euclidean dimension of 2 and where the geometrical similarity was kept. In addition the analysis showed that the distribution of the diameters of the islands was narrow in this region. As Al average thickness increased more, islands were connecting together, increasing a fraction of area covered by Al islands. In this Al thickness region, fractal dimensions were more than 2.5 and an Euclidean dimension did not define the stucture. In this region the geometrical similarity of the structure was not found, though the structure kept the statistical similarity.Although the fractal dimension was well determined for the network structure, the network structure was thought to be fractal because the structure was obtained by growing the island structure further at a higher temperature keeping the perimeter shapes of asch islands.III.ConclusionsThe Al/Ti bilayr films were deposited by dc magnetron sputtering.At a Al thickness of 20 to 50nm, Al islands structure obtained were fractal. By increasing the substrate temperature further, the network-like structure was obtained. The network-like structure was thought to be fractal although the fractal dimensions were well defined for the network-like structure because of its complexity that caused the difficulty to apply a lake filling method to obtain the dimension. Less

1 .实验步骤- Al/Ti多层膜的形成-采用直流磁控溅射沉积了分形岛状或网状结构。实验中使用的阴极是两个直径为75mm的磁控管，安装在由涡轮分子泵泵送的超高真空室中。靶材为Al（99.99%）和Ti（99.98%）。所使用的基材是铝硼硅酸盐玻璃。排出气体为Ar（99.9999%）。底物温度在200 ~ 600℃之间变化。为了加速Al薄膜岛状结构的形成，首先在衬底上沉积Ti层，然后在不破坏真空的情况下在Ti层上依次沉积Al层。（钛表面的氧化恶化了孤立Al岛结构的形成。）在整个沉积过程中，Ti下层的厚度为500nm， Al层的厚度从10nm变化到80nm。利用原子力扫描探针显微镜（AFM,Topo-Metrix: Type TMX-2000）分析了沉积膜的表面形貌。扫描范围为10mum平方，300x300位。利用数字化的AFM数据，采用湖泊填充法获得了岛屿或网络维数的分形维数。2 .实验结果-表面形貌及分形维数-在550C下沉积的铝平均厚度为20 ~ 40nm时，原子力显微镜可获得岛直径约0.5 ~ 1nm的孤岛结构。每个岛的大直径是Al/Ti双层岛结构的特征。随着衬底温度的进一步升高，其中心呈岛状凸出，形成网状结构。对岛状结构和网状结构进行了分形维数的测定。由于网络形状的复杂性，湖泊填充法对海岛结构的分形维数获得较好，而对网络形状的分形维数无法得到较好的分形维数。海岛结构的分形维数在2.0 ~ 2.2之间。分形维数在2.0左右表明，这些Al厚度值下的岛状膜生长为二维生长，分形维数几乎等于欧几里得维数2，且几何相似度保持不变。此外，分析表明，该地区岛屿直径分布较窄。随着人工智能的平均厚度增加，岛屿连接在一起，增加了人工智能岛屿覆盖的一小部分面积。在该Al厚度区域，分形维数大于2.5，欧几里得维数不能定义结构。在这一区域，虽然结构保持了统计上的相似性，但没有发现结构的几何相似性。虽然网状结构的分形维数得到了很好的确定，但我们认为网状结构是分形的，因为这种网状结构是在保持asch岛的周长形状的前提下，在较高的温度下进一步生长得到的。在Al厚度为20 ~ 50nm时，得到的Al岛状结构呈分形。通过进一步提高衬底温度，得到了网状结构。尽管网状结构的分形维数已经定义得很好，但由于其复杂性，难以用湖泊填充法获得分形维数，因此认为网状结构是分形的。少

项目成果

E.Kusano, et.al.: "Fractal Analysis of Island Structure of Al Thin Films" TATF Proceedings. (in press).

E.Kusano 等人：“铝薄膜岛结构的分形分析”TATF 论文集。

E.Kusano et.al.: "Vanadium Reactive Magnetron Sputtering in Mixed Ar/O_2 Discharge" Thin Solid Films. 298. 122-129 (1997)

E.Kusano 等人：“混合 Ar/O_2 放电中的钒反应磁控溅射”固体薄膜。

A.Kinbara, et.al.: "Growth mechanism of Si nodules on BPSG" Thin Solid Films. 270. 445-449 (1996)

A.Kinbara 等人：“BPSG 上硅结核的生长机制”固体薄膜。

E.Kusano, M.Kitagawa, H.Nannto, and A.Kinbara: "A Hardness Enhancement by Compositionally Modulated Structure of Ti/TiN Multilayr Films" Journal of Vacuum Science and Technology. (in press).

E.Kusano、M.Kitakawa、H.Nannto 和 A.Kinbara：“通过 Ti/TiN 多层薄膜的成分调制结构提高硬度”真空科学与技术杂志。

E.Kusano and A.Kinbara: "Formation of compositionally graded multilayer by discharge gas flow modulation in ・・・・" Journal of Non-crystalline solid. 218. 58-61 (1997)

E.Kusano 和 A.Kinbara：“在……中通过放电气流调制形成成分梯度多层”《非晶固体杂志》218. 58-61 (1997)。