Name: fabrication of magnetic nanostructures on silicon nitride membranes for magnetic vortex studies using transmission microscopy techniques
Uploaded: 2018-07-02T14:00:00.000+00:00
Duration: 6 min 27 s
Description: Watch this Scientific Journal Video about Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques at JoVE.com

这项研究得到了捷克共和国赠款机构 (项目号 15-34632L) 和 CEITEC 纳米 + 项目的财政支持, 02.1. 01/0.0/0.0/16 013/0001728。在 CEITEC 纳米研究基础设施 (ID LM2015041, MEYS CR, 2016-2019) 中进行了样品制作和 LTEM 测量。Meena Dhankhar 获得了布尔诺博士学位奖学金的支持。

我们演示了一种制备 TEM 和 MTXM 样品的方法。坡莫合金 nanodiscs 直径范围从 250-4000 毫微米和厚度在 20-100 毫微米之间在30毫微米厚的罪孽膜被制造为 TEM 和200毫微米厚的罪孽膜为 MTXM。图 1显示了罪恶膜的照片。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57817/57817fig1.jpg"> 图 1: 用作 MTXM (左) 和 TEM (右) 样品的基片的罪恶膜的照片.图像显示标尺的大小比较。MTXM 框架是一个 5 x 5 毫米矩形与窗口厚度200毫微米和 TEM 框架适合一个3毫米圆直径与窗口厚度30毫微米。<a href="/files/ftp_upload/57817/57817fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
1. 透射电镜样品的制作
注: 在本节中, 我们描述了用于观测磁涡流17的成核过程的 TEM 样品的制作。膜被选择为基材, 因为它们为磁性结构的 lithographical 制造提供了坚实的支持。一个重要的参数是膜的窗口厚度。较高的加速电压允许穿透较厚的样品, 但任何不必要的厚度将导致信号损失19。因此, 我们使用我们的供应商提供的最薄的薄膜 (30 nm)。
<ol><li>
衬底制备和自旋涂层 注: 自旋涂层是一种广泛使用的工艺, 以获得理想的抗膜在基板上。少量的抵抗被丢弃在基板上, 然后以非常高的速度旋转以获得所需的涂层厚度。TEM 膜的自旋涂层是相当奇特的, 因为以下原因: (i) 如果膜是纺在旋转涂布机的轴, 抵抗不会是统一的, 由于膜的小直径和 (ii) 真空支架不能使用, 因为他们可以打破膜。为此, 我们设计了3D 打印适配器 (见图 2), 它保持膜离轴, 不需要真空来保存样品。<ol>
<li>焙在180摄氏度的热板上的罪孽膜, 以去除任何湿气。</li>
		<li>在旋转涂布机上插入适配器, 然后将膜置于适配器中。</li>
		<li>自旋涂层 950 K PMMA (聚甲基丙烯酸甲酯) 抵抗在3000转每分钟1分钟, 以产生大约 200 nm 的薄膜厚度。</li>
		<li>后烘烤的热板上的样品在180°c 3 分钟硬化 PMMA 层。</li>
	</ol>
</li>
</ol><img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57817/57817fig2.jpg"> 图 2: 3D 打印适配器的照片, 用于在自旋涂层中保持 TEM 膜离轴.多膜可同时涂覆。<a href="/files/ftp_upload/57817/57817fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol start="2"><li>
电子束光刻 (EBL)
	<ol>
<li>绘制图形数据库系统 (GDS) 格式的光盘所需的图案, 并将其上载到电子束 (电子束) 光刻系统。</li>
		<li>将样品加载到电子束写入器系统中, 设置舞台和光束。</li>
		<li>将光盘区域暴露在20凯文的光束能量为260µC/厘米2的电子剂量。 注: 博览会过程的合适参数为 250 pA 的光束电流, 步长为 10 nm。与大块基底相比, 这种剂量约为 30%, 因为膜上的背向散射高度降低。</li>
	</ol>
</li>
	<li>
化学发展
	<ol>
<li>暴露后, 在甲基异丁基酮 (MIBK) 的开发者中开发样品2分钟. 用异丙醇 (IPA) 在三十年代停止发展。</li>
		<li>三十年代把每个样品洗去去离子水, 用氮气吹干, 同时拿着镊子。</li>
		<li>使用光学显微镜在低放大倍数 (使用5X 目标), 然后在高放大倍数 (使用100X 目标) 检查样品的发展;图 3显示了一个被开发的样本的光学显微镜图像。</li>
	</ol>
</li>
	<li>
电子束蒸发 注: 电子束蒸发20是一种物理气相沉积形式, 在高真空下由带电钨灯丝产生的高能电子束轰击目标阳极。电子束使原子从目标转变成气态相。这些原子沉淀成固体形式, 将真空室中的所有东西都涂上薄薄的靶材层。最好是使用电子束蒸发系统的升降目的, 因为它给了一个很好的边缘的光盘, 而不存入任何额外的材料光盘的边界。<ol>
<li>将膜小心地用聚 oxydiphenylene pyromellitimide (如Kapton) 贴在支架上, 并通过负载锁将其转移到电子束蒸发器的沉积室中。</li>
		<li>使用电子束蒸发系统将薄层的坡莫合金 (镍80Fe20) 沉积, 其厚度范围从20到 100 nm, 沉积速率约为 1 Aͦ/秒. 使用 8 kV 的加速度电压和光束电流大约 120 mA。</li>
	</ol>
</li>
	<li>
升降
	<ol>
<li>用丙酮 (至少99.5% 纯度) 将1小时的膜放入烧杯中。</li>
		<li>现在用丙酮喷雾膜, 同时用镊子, 直到多余的金属被除去。</li>
		<li>如果多余的金属残留在样品上, 请将膜放回烧杯中, 然后重复该过程。 注: 可选择使用兆声浴来辅助升降过程。请注意, 它是不可能使用经典的超声波浴, 因为它打破了膜。</li>
		<li>用扫描电子显微镜 (SEM) 在5伏的加速电压和 100 pA 的束流中进行最终检查, 将最终的磁片阵列图像。图 3b显示了100,000X 放大倍数的图像。</li>
	</ol>
</li>
	<li>
LTEM 成像
	<ol>
<li>将样品装入 TEM 样品架中, 并将其插入显微镜中。</li>
		<li>使用显微镜的标准程序, 校正样品高度并将洛仑兹模式的显微镜对准所需的加速电压 (在我们的案例中为 300 kV)。</li>
		<li>引入磁信号, 将洛仑兹透镜离焦。</li>
		<li>继续做实验。倾斜样品, 以引入平面场组件 (例如, 合适的角度是 30°, 检查持有人的规格最大倾角)。</li>
		<li>应用磁场刺激物镜 (通常在洛仑兹模式下关闭)。 注: 现场校准曲线应由 TEM 制造商提供。</li>
		<li>对样品进行饱和, 通过 deexciting 物镜, 在相机上捕捉图像, 逐渐减小磁场。示例结果如图 3c所示。</li>
	</ol>
</li>
</ol><img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57817/57817fig3.jpg"> 图 3: 由光学和电子镜成像的最终样本.(a) 该面板显示了氮化硅膜窗口, 其阵列中的圆盘在电子束曝光后抵抗发展。(b) 本小组展示了扫描电镜所成像的磁片的最终阵列. (c) 此面板显示磁性 nanodiscs 阵列中磁性涡核态的 LTEM 图像。<a href="/files/ftp_upload/57817/57817fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
2. MTXM 样品的制作
注: 在 MTXM 测量中, 我们可以利用该技术的时间分辨率。为了引入高频励磁涡旋, 在第一步制造一个金波导, 然后在第二光刻步骤中将磁片放在波导的顶部。整个结构是捏造的 200 nm 厚的罪恶膜, 这是透明足够的软 x 射线21。详细步骤将在下面的文本中描述, 流程的示意图如图 4所示。MTXM 样品的制作过程贯穿上述的所有步骤, 为 TEM 样品制作, 但需要额外的光刻步骤, 以制造波导。
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57817/57817fig4.jpg"> 图 4: 在 MTXM 时间分辨实验中, 在氮化硅膜上使用圆盘和波导的样品的制备步骤的示意图.它涉及两步光刻, 以获得最终的结构。<a href="/files/ftp_upload/57817/57817fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol><li>样品制备和自旋涂层 注: MTXM 膜为 5 x 5 毫米2帧, 具有 3 x 3 毫米2宽和 200 nm 厚的中央窗口。膜不能放在旋转涂布机真空卡盘, 因为它会打破膜。在这种情况下, 我们胶合膜到一个 10 x 10 毫米2硅片, 使其易于使用。<ol>
<li>焙180摄氏度的热板上的罪孽样品, 以去除样品中的水分。</li>
		<li>自旋涂层正面抵抗凯撒在3000转每分钟1分钟;产生的薄膜厚度约为500纳米。 注意: 这种类型的抵抗被选择为其更高的灵敏度, 导致更快的写作时间。在抵抗数据表上可以找到厚度-自旋速度依赖性。</li>
		<li>在热板上烘烤样品在150°c 1 分钟硬化抵抗层。</li>
	</ol></li>
	<li>波导电子束光刻
	<ol>
<li>以 GDS 格式创建所需的波导和对准标记 (用于第二光刻步骤) 的模式, 并将其上载到电子束光刻系统。</li>
		<li>将样品加载到电子束写入器系统中, 设置舞台和光束。</li>
		<li>将光盘区域暴露在20凯文的光束能量为65µC/厘米2的电子剂量, 一个 10 nA 的光束电流, 和一个台阶尺寸 200 nm。 注: 我们使用凯撒正面抵抗公开波导和对准标记。这种抗性比 PMMA 具有更高的灵敏度, 电子剂量的65微机/cm2在光束能量20凯文, 因此, 有利于加快博览会。</li>
	</ol></li>
	<li>化学发展
	<ol>
<li>曝光后, 开发的样品在开发商为1分钟, 并遵循这一塞子 (IPA) 三十年代。</li>
		<li>三十年代把样品洗去去离子水, 用镊子把它们吹干, 用氮气把它们擦干。</li>
	</ol></li>
	<li>电子束蒸发
	<ol>
<li>使用电子束蒸发器将 Ti (3 nm)/Au (100 nm) 双层沉积在波导和对准标记上。</li>
		<li>以 10 rpm 的速度连续旋转样品以增加层的均匀性。 注: 钛层的 3-5 nm, 使胶粘剂接触之间的罪孽样品和 Au 层。金层的厚度通常介于 80-120 nm 之间。这范围的厚度是适合的电线粘合的样品到定制印制电路板, 我们用来注入电流脉冲到波导。</li>
		<li>使用 0.5-0.7 Aͦ/秒的 Ti 的沉积率和 2.5 Aͦ/秒的 Au. 保持电子束系统的基本压力在大约 10-7毫巴或更好。</li>
		<li>或者, 用铜代替 Au 来制作波导, 以提高软 x 射线的透明度。</li>
	</ol></li>
	<li>升降
	<ol>
<li>钛/金薄膜沉积后, 将样品放入丙酮中1小时。</li>
		<li>现在, 用丙酮喷雾膜, 直到多余的金属被除去。</li>
		<li>如果多余的金属残留在样品上, 将它们放回烧杯中丙酮, 然后重复该过程。 注: 可以选择使用兆声浴来支持升降过程。样品与钛/金波导结构, 并与对准标记再次通过相同的光刻步骤, 以制作的磁光盘在波导上。</li>
	</ol></li>
	<li>2沉积
	<ol>
<li>将样品与波导和对准标记插入原子层沉积系统, 并将2层沉积 20 nm, 使波导和圆盘之间的绝缘层。</li>
		<li>用钛前体四 (dimethylamido) 钛 (TDMAT) 和 H2O 为2的氧等离子体沉积, 并以 0.51 Aͦ/周期的速率生长。</li>
	</ol></li>
	<li>样品的自旋涂层 注: 我们使用双层的抵抗, 以提高光盘的边缘质量。在电子束照射的过程中, 底部的抵抗是过量的, 在开发之后, 它提供了一个精致的切边。<ol>
<li>焙在热板上的样品在180°c 15 分钟, 以消除水分。</li>
		<li>自旋涂层共聚物抵抗在4000转每分钟1分钟。 注: 所产生的薄膜厚度约为30纳米。</li>
		<li>后烘烤的热板上的样品在180°c 3 分钟硬化抵抗。</li>
		<li>自旋涂层 PMMA 950K 抵抗在4000转每分钟1分钟。产生的薄膜厚度约为270纳米。</li>
		<li>后烘烤样品在180°c 3 分钟硬化抵抗。</li>
	</ol></li>
	<li>圆盘电子束光刻
	<ol>
<li>创建第二个 lithographical 模式的光盘的 GDS 格式, 并上传到电子束光刻系统。</li>
		<li>使用全局标记将 UV 协调系统与示例对齐。</li>
		<li>使用本地标记对齐写字段, 以便校准写字段的大小、旋转和移位, 以确保光盘在波导上的正确位置。</li>
		<li>将光盘区域暴露在20凯文的光束能量的电子剂量为220µC/厘米2 。使用 200-300 pA 的光束电流和一步大小为 10 nm 以暴露图案。</li>
	</ol></li>
	<li>化学发展
	<ol>
<li>在一个以 MIBK 为基础的开发人员中开发1分钟的样品, 并在三十年代用塞子 (IPA)。</li>
		<li>然后冲洗样品在去离子水三十年代和吹干他们与氮气, 同时拿着镊子。</li>
	</ol></li>
	<li>离子束溅射沉积
	<ol>
<li>将样品插入离子束溅射系统。</li>
		<li>根据溅射材料的方向倾斜试样持有者, 以便通过阴影效应使圆盘锥度变细。 注: 锥度用于控制涡旋环流11的开关。</li>
		<li>在大约 0.50.7毫巴的工作压力下, 用 10--5 Aͦ/秒的沉积速率将 20-50 nm 厚的坡莫合金 (镍80Fe20) 层存入。 注: 基本压力应为 10-7毫巴或更好。</li>
	</ol></li>
	<li>升降
	<ol>
<li>把样品放在丙酮中1小时。</li>
		<li>现在, 用丙酮喷雾膜, 同时把它们放在镊子中, 直到去除多余的金属。</li>
		<li>如果多余的金属残留在样品上, 请将样品放回烧杯中丙酮, 然后重复该过程。 注: 可以选择使用兆声浴来支持升降过程。我们得到了坡莫合金光盘的最终结构在一个钛/Au 波导上的罪恶膜, 如图 5所示。</li>
	</ol></li>
</ol><img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57817/57817fig5.jpg"> 图 5: 扫描电镜图像的最终结构30毫微米厚和2µm 宽坡莫合金光盘上的黄金波导与对准标记.这些样品进一步用于时间分辨的 MTXM 实验。<a href="/files/ftp_upload/57817/57817fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

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A., Novosad, V., Otani, Y., Shima, H., Fukamichi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eigenfrequencies+of+vortex+state+excitations+in+magnetic+submicron-size+disks.">Eigenfrequencies of vortex state excitations in magnetic submicron-size disks.</a> Journal of Applied Physics. 91 (10), 813-823 (2002).</li><li>Urb&#225;nek, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+and+efficiency+of+magnetic+vortex+circulation+reversal.">Dynamics and efficiency of magnetic vortex circulation reversal.</a> Physical Review B. 91, 094415 (2015).</li><li>Uhl&#237;&#345;, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+switching+of+the+spin+circulation+in+tapered+magnetic+nanodisks.">Dynamics switching of the spin circulation in tapered magnetic nanodisks.</a> Nature Nanotechnology. 8 (5), 341-346 (2013).</li><li>Jung, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Logic+operations+based+on+magnetic-vortex-state+networks.">Logic operations based on magnetic-vortex-state networks.</a> ACS Nano. 6 (5), 3712-3717 (2012).</li><li>Hasegawa, N., Sugimoto, S., Fujimori, H., Kondou, K., Niimi, Y., Otani, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+mode+excitation+in+three-chained+magnetic+vortices.">Selective mode excitation in three-chained magnetic vortices.</a> Applied Physics Express. 8 (6), 063005 (2015).</li><li>Wintz, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+vortex+cores+as+tunable+spin-wave+emitters.">Magnetic vortex cores as tunable spin-wave emitters.</a> Nature Nanotechnology. 11, 948-953 (2016).</li><li>Hopster, H., Oepen, H. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Magnetic Microscopy of Nanostructures. , (2005).</li><li>Fischer, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+imaging+with+polarized+soft+x-rays.">Magnetic imaging with polarized soft x-rays.</a> Journal of Physics D: Applied Physics. 50 (31), 313002 (2017).</li><li>Vanatka, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+vortex+nucleation+modes+in+static+magnetic+fields.">Magnetic vortex nucleation modes in static magnetic fields.</a> AIP Advances. 7 (10), 105103 (2017).</li><li>Constancias, C., Landis, S., Manakli, S., Martin, L., Pain, L., Rio, D., Landis, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+beam+lithography.">Electron beam lithography.</a> Lithography. , (2013).</li><li>Williams, D. B., Carter, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Transmission Electron Microscopy. A Textbook for Materials Science. , (2009).</li><li>Seshan, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook of Thin-film Deposition Processes and Techniques. , (2002).</li></ol>

作者没有什么可透露的。

我们已经展示了 LTEM 和 MTXM 磁性镜样品的制作。这些样品需要在薄的罪孽膜上制作, 这样, 在 LTEM 的情况下, 和软 x 射线的电子, 在 MTXM 的情况下, 可以穿透样品。这些样品可以制造 1) 正面抵抗光刻或 2) 消极抵抗光刻。
我们使用了正面抗光刻技术, 因为它需要更少的样品准备和更少的制造步骤, 并允许更容易的处理。它还允许研究员使用的阴影效果, 我们用于精确的圆盘形状控制 (圆盘一侧的渐狭)。该形状用于控制在核10,11的磁性涡旋的循环。
这种技术的缺点是复杂的升降过程, 因为薄膜材料有时沉积在抗力边缘上, 不能通过升降来去除。我们使用双抗层来解决这个问题。这稍微限制了 lithographical 过程的分辨率 (约 20 nm), 但仍足以用于磁性成像。
消极抵抗光刻技术提供一个更高的决议作为结构以决议下来到7毫微米可以被写入抵抗。然后用湿蚀刻或离子束蚀刻将材料蚀刻掉。这种方法的问题是, 在蚀刻后, 抵抗很难去除。在薄坡莫合金结构的情况下, 通常使用的氧等离子体抗剥离是不可能的, 因为它们很容易氧化。这一事实, 连同使用隐藏技术的需要, 有利于在整个工作中使用的正光刻过程。
我们使用本文所述方法制备的样品, 用于观察 MTXM10、11和不同核态17的循环切换过程中的磁涡动力学..这可以扩展到更多的实验类型, 需要 lithographically 制备的膜结构。

近两年来, 随着技术走向小型化, 纳米结构的磁性得到了深入的研究。随着结构的横向尺寸变小, 铁磁结构的磁性特性也开始受结构几何的影响, 除了磁性材料的性质外。从散装材料到显微组织的不同磁性元素的行为被详细审查 (例如,休伯特和赫尔穆特·舍费尔)1。非平凡磁化地面状态最著名的例子之一是磁性涡旋-卷曲磁化结构发生在微米和亚微米大小的薄磁盘和多边形。这里的磁化是在平面上绕出平面涡核2,3。磁涡的磁化反转在静态4、5、6和动态7、8、9、10中得到了广泛的研究。政权。磁涡的可能的应用是,例如,多比特记忆细胞11, 逻辑电路12, 射频设备13, 或自旋波发射器14。
为了成像磁涡, 特别是涡核, 显微技术的空间分辨率应尽可能接近基本的磁性长度刻度 (低于 10 nm)。洛仑兹透射电镜15 (LTEM) 和磁透射 x 射线显微镜16 (MTXM) 是磁涡流成像的理想候选者, 因为它们提供了高空间分辨率, 而且 MTXM 也提供了高的时间磁化动力学研究的决议。这些技术的缺点是复杂的样品准备, 这是本文的主题。
这里介绍的过程解释了用 TEM17和 MTXM10,11制作成像磁涡的样品。这两种技术都具有传输特性, 因此, 在薄膜上制造结构是必要的。膜通常由氮化硅制成, 其厚度范围从纳米到几上百纳米。这两种方法中的每一个都需要不同的支持框架几何图形。在 MTXM 的情况下, 框架是 5 x 5 毫米2和窗口是大的, 2 x 2 毫米2。在 TEM 的情况下, 框架几何是一个直径为3毫米的圆圈, 其大小取决于实验的窗口尺寸, 通常为 250 x 250 µm2。膜带来了更多的挑战, 更困难的样品处理, 有打破窗口在所有的光刻过程的风险。
样品的制作可以通过正负抗光刻技术进行18。正抗光刻工艺采用正面抗蚀;化学结构的抵抗变化后, 辐照和暴露的部分将成为可溶性在化工开发商。暴露的区域将会冲走, 而未曝光的区域将留在基板上。在负阻光刻过程中, 辐照硬化了抗性, 暴露的区域将保留在基体上, 而未曝光区域将在化学显影中冲洗掉。这两种技术都可以用于样品的制作, 但是我们更喜欢正面抗光刻, 因为与负阻光刻技术相比, 它需要较少的制造步骤。它也更容易处理, 更快, 并经常提供更好的结果。

<table><tbody><tr><td>SiN Membrane - TEM</td><td>Silson</td><td>SiRN-TEM-200-0.25-500</td><td>TEM membrane</td></tr><tr><td>SiN Membrane - MTXM</td><td>Silson</td><td>SiRN-5.0-200-3.0-200</td><td>MTXM membrane</td></tr><tr><td>3D adapter for spin coating</td><td></td><td></td><td>The model of the adapter for 3D printing can be downloaded at: https://www.thingiverse.com/thing:2808368</td></tr><tr><td>PMMA 950k electron beam resist</td><td>Allresist</td><td>AR-P 679.04</td><td>used for TEM sample</td></tr><tr><td>Electron beam resist developer</td><td>Allresist</td><td>AR 600-56</td><td>used for TEM sample</td></tr><tr><td>High-contrast electron beam resist</td><td>Allresist</td><td>AR-P 6200.13</td><td>used for the waveguide on the MTXM sample</td></tr><tr><td>High-contrast electron beam resist developer</td><td>Allresist</td><td>AR-600-546</td><td>used for the waveguide on the MTXM sample</td></tr><tr><td>Tetrakis(dimethylamido)titanium(IV)</td><td>Sigma Aldrich</td><td>669008 Aldrich&amp;nbsp;</td><td>used for TiO2 thin film deposition by ALD&amp;nbsp;</td></tr><tr><td>Electron beam resist for nanometer lithography</td><td>Allresist</td><td>AR-P 617.02</td><td>used as the bottom layer of bilayer resist for easier lift-off procedure</td></tr><tr><td>PMMA 950k electron beam resist</td><td>Allresist</td><td>AR-P 679.04</td><td>used as the top layer of bilayer resist for easier lift-off procedure</td></tr><tr><td>Electron beam resist developer</td><td>Allresist</td><td>AR 600-56</td><td>used for development of the disks on waveguide</td></tr><tr><td>Permalloy pellets</td><td>Kurt J Lesker</td><td>EVMPERMQXQ-D</td><td>used for the deposition of the magnetic layers</td></tr><tr><td>Titanium pellets</td><td>Kurt J Lesker</td><td>EVMTI45QXQD</td><td>used as adhesive layer for the gold waveguide</td></tr><tr><td>Gold pellets</td><td>Kurt J Lesker</td><td>EVMAUXX40G</td><td>used for the deposition of the waveguide</td></tr></tbody></table>

fabrication of magnetic nanostructures on silicon nitride membranes for magnetic vortex studies using transmission microscopy techniques

电子和 x 射线磁性镜允许高分辨率的磁性成像向下到十纳米。然而, 样品需要在透明的膜上制备, 这些薄膜非常脆弱且难于操作。我们提出了制造样品的过程, 磁性微-和纳米结构的旋转构型形成磁涡, 适用于洛伦兹透射电镜和磁性透射 x 射线显微学研究。样品是在氮化硅膜上制备的, 其制备过程包括自旋涂层、紫外和电子束光刻、抗化学发展、磁性材料的蒸发, 然后是形成最后的磁性结构。洛仑兹透射电子显微术的样品包括在单光刻步骤中制备的磁性 nanodiscs。用磁性 x 射线透射显微镜样品进行时间分辨磁化动态实验, 将磁 nanodiscs 放在波导上, 用于产生可重复的磁场脉冲, 通过电电流通过波导。波导是在额外的光刻步骤中创建的。

图 1显示了用于 MTXM 和 LTEM 镜的罪恶框架和膜的照片。图 2显示了在自旋涂层过程中, 3 维打印适配器的设计, 用于将 TEM 膜脱离轴。图 3显示了 LTEM 样品准备的各个步骤 (在抵抗发展之后和起飞过程之后) 和 LTEM 观察到的最终图像。图 4显示了在 MTXM 时间分辨实验中, 为制作圆盘和在 SiN 膜上的波导而准备步骤的示意图。图 5 显示了包含放在波导上的光盘的最终 MTXM 样本。

Watch this Scientific Journal Video about Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques at JoVE.com

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

提出了一种适用于透射电镜 (TEM) 和磁透射 x 射线显微术 (MTXM) 研究的磁涡流成形磁性微纳米结构的制备方法。

用透射显微技术制备氮化硅薄膜磁性纳米结构的研究

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

fabrication-magnetic-nanostructures-on-silicon-nitride-membranes-for

Research

JoVE Journal

Engineering

8.0K 次观看.  Brno University of Technology. 提出了一种适用于透射电镜 (TEM) 和磁透射 x 射线显微术 (MTXM) 研究的磁涡流成形磁性微纳米结构的制备方法。

视频: Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Fabricating Nanogaps by Nanoskiving

There are several methods of fabricating nanogaps with controlled spacings, but the precise control over the sub-nanometer spacing between two electrodes-and generating them in practical quantities-is still challenging. The preparation of nanogap electrodes using nanoskiving, which is a form of edge lithography, is a fast, simple and powerful technique. This method is an entirely mechanical process which does not include any photo- or electron-beam lithographic steps and does not require any special equipment or infrastructure such as clean rooms. Nanoskiving is used to fabricate electrically addressable nanogaps with control over all three dimensions; the smallest dimension of these structures is defined by the thickness of the sacrificial layer (Al or Ag) or self-assembled monolayers. These wires can be manually positioned by transporting them on drops of water and are directly electrically-addressable; no further lithography is required to connect them to an electrometer.

The fabrication of electrically addressable, high-aspect-ratio (> 1000:1) metal nanowires separated by gaps of single nanometers using either sacrificial layers of aluminum and silver or self-assembled monolayers as templates is described. These nanogap structures are fabricated without a clean room or any photo- or electron-beam lithographic processes by a form of edge lithography known as nanoskiving.

制造由Nanoskiving Nanogaps的

There are several methods of fabricating nanogaps with controlled spacings, but the precise control over the sub-nanometer spacing between two ...

科研

化学

Fabrication of Uniform Nanoscale Cavities via Silicon Direct Wafer Bonding

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned and bonded silicon wafers. Unlike confinements in porous materials often used for these types of experiments3, bonded wafers provide predesigned uniform spaces for confinement. The geometry of each cell is well known, which removes a large source of ambiguity in the interpretation of data.
Exceptionally flat, 5 cm diameter, 375 &#181;m thick Si wafers with about 1 &#181;m variation over the entire wafer can be obtained commercially (from Semiconductor Processing Company, for example). Thermal oxide is grown on the wafers to define the confinement dimension in the z-direction. A pattern is then etched in the oxide using lithographic techniques so as to create a desired enclosure upon bonding. A hole is drilled in one of the wafers (the top) to allow for the introduction of the liquid to be measured. The wafers are cleaned2 in RCA solutions and then put in a microclean chamber where they are rinsed with deionized water4. The wafers are bonded at RT and then annealed at ~1,100 &#176;C. This forms a strong and permanent bond. This process can be used to make uniform enclosures for measuring thermal and hydrodynamic properties of confined liquids from the nanometer to the micrometer scale.

A method for permanently bonding two silicon wafers so as to realize a uniform enclosure is described. This includes wafer preparation, cleaning, RT bonding, and annealing processes. The resulting bonded wafers (cells) have uniformity of enclosure ~1%1,2. The resulting geometry allows for measurements of confined liquids and gasses.

通过硅直接晶圆粘接制造均匀纳米级腔

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned ...

工程学

Fabrication and Operation of a Nano-Optical Conveyor Belt

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological and physical sciences over the past few decades. The progress made in this field invites further study of even smaller systems and at a larger scale, with tools that could be distributed more easily and made more widely available. Unfortunately, the fundamental laws of diffraction limit the minimum size of the focal spot of a laser beam, which makes particles smaller than a half-wavelength in diameter hard to trap and generally prevents an operator from discriminating between particles which are closer together than one half-wavelength. This precludes the optical manipulation of many closely-spaced nanoparticles and&#160;limits the&#160;resolution of optical-mechanical systems. Furthermore, manipulation using focused beams requires beam-forming or steering optics, which can be very bulky and expensive. To address these limitations in the system scalability of conventional optical trapping our lab has devised an alternative technique which utilizes near-field optics to move particles across a chip. Instead of focusing laser beams in the far-field, the optical near field of plasmonic resonators produces the necessary local optical intensity enhancement to overcome the restrictions of diffraction and manipulate particles at higher resolution. Closely-spaced resonators produce strong optical traps which can be addressed to mediate the hand-off of particles from one to the next in a conveyor-belt-like fashion. Here, we describe how to design and produce a conveyor belt using a gold surface patterned with plasmonic C-shaped resonators and how to operate it with polarized laser light to achieve super-resolution nanoparticle manipulation and transport. The nano-optical conveyor belt chip can be produced using lithography techniques and easily packaged and distributed.

The scalability and resolution of conventional optical manipulation techniques are limited by diffraction. We circumvent the diffraction limit and describe a method of optically transporting nanoparticles across a chip using a gold surface patterned with a path of closely spaced C-shaped plasmonic resonators.

一个纳米光输送带的制作和操作

The technique of using focused laser beams to trap and exert forces on small particles has enabled many pivotal discoveries in the nanoscale biological ...

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

原子纳米结构可追溯制造

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

对于新材料的低温磁输运测量先进的实验方法

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Scanning SQUID Study of Vortex Manipulation by Local Contact

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual vortices is necessary in order to study how vortices interact with each other, with the lattice, and with other magnetic objects. Here, we present a protocol for vortex manipulation in thin superconducting films by local contact, without applying current or magnetic field. Vortices are imaged using a scanning superconducting quantum interference device (SQUID), and vertical stress is applied to the sample by pushing the tip of a silicon chip into the sample, using a piezoelectric element. Vortices are moved by tapping the sample or sweeping it with the silicon tip. Our method allows for effective manipulation of individual vortices, without damaging the film or affecting its topography. We demonstrate how vortices were relocated to distances of up to 0.8 mm. The vortices remained stable at their new location up to five days. With this method, we can control vortices and move them to form complex configurations. This technique for vortex manipulation could also be implemented in applications such as vortex based logic devices.

We present a protocol for manipulation of individual vortices in thin superconducting films, using local mechanical contact. The method does not include applying current, magnetic field or additional fabrication steps.

由当地接触式扫描涡操纵SQUID研究

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

Iron Nanowire Fabrication by Nano-Porous Anodized Aluminum and its Characterization

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and data storage. We demonstrate a fabrication method for iron (Fe) nanowires&#160;via electrochemical deposition into anodic&#160;alumina oxide (AAO) templates. The templates are fabricated by anodization of aluminum (Al) discs, and the pore length and diameter are controlled by changing the anodizing conditions. Pores with an average diameter of around 120 nm are created using oxalic acid as the electrolyte. Using this method, cylindrical nanowires are synthesized, which are released by dissolving the alumina using a selective chemical etchant.

In this work, we describe a&#160;protocol to fabricate iron nanowires, including the formation of the porous alumina membrane that is used as the template, electrodeposition into templates using electrolyte solution, and the release of the nanowires into the solution.

纳米孔阳极氧化铝的铁纳米线制造及其特性

Magnetic nanowires possess unique properties that have attracted the interest of different fields of research, including basic physics, biomedicine, and ...

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by overlapping two parts of an electron wave, one of which has passed through a region of interest on a specimen and the other is a reference wave. The resulting off-axis electron hologram can be analyzed digitally to recover the phase difference between the two parts of the electron wave, which can then be interpreted to provide quantitative information about local variations in electrostatic potential and magnetic induction within and around the specimen. Off-axis electron holograms can be recorded while a specimen is subjected to external stimuli such as elevated or reduced temperature, voltage, or light. The protocol that is presented here describes the practical steps that are required to record, analyze, and interpret off-axis electron holograms, with a primary focus on the measurement of magnetic fields within and around nanoscale materials and devices. Presented here are the steps involved in the recording, analysis, and processing of off-axis electron holograms, as well as the reconstruction and interpretation of phase images and visualization of the results. Also discussed are the need for optimization of the specimen geometry, the electron optical configuration of the microscope, and the electron hologram acquisition parameters, as well as the need for the use of information from multiple holograms to extract the desired magnetic contributions from the recorded signal. The steps are illustrated through a study of specimens of B20-type FeGe, which contain magnetic skyrmions and were prepared with focused ion beams (FIBs). Prospects for the future development of the technique are discussed.

Guidelines are presented for recording and interpreting off-axis electron holograms to provide quantitative images of magnetic fields in nanoscale materials and devices in the transmission electron microscope.

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by ...

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force microscopy (AFM) probe whose tip has been magnetized vertically (i.e., perpendicular to the probe cantilever) is oscillated at a fixed height above the sample surface. The resultant shifts in the oscillation phase or frequency, which are proportional to the magnitude and sign of the vertical magnetic force gradient at each pixel location, are then tracked and mapped. Although the spatial resolution and sensitivity of the technique increases with decreasing lift height above the surface, this seemingly straightforward path to improved MFM images is complicated by considerations such as minimizing topographical artifacts due to shorter range van der Waals forces, increasing the oscillation amplitude to further improve sensitivity, and the presence of surface contaminants (in particular water due to humidity under ambient conditions). In addition, due to the orientation of the probe's magnetic dipole moment, MFM is intrinsically more sensitive to samples with an out-of-plane magnetization vector. Here, high-resolution topographical and magnetic phase images of single and bicomponent nanomagnet artificial spin-ice (ASI) arrays obtained in an inert (argon) atmosphere glovebox with &lt;0.1 ppm O2 and H2O are reported. Optimization of lift height and drive amplitude for high resolution and sensitivity while simultaneously avoiding the introduction of topographical artifacts is discussed, and detection of the stray magnetic fields emanating from either end of the nanoscale bar magnets (~250 nm long and &lt;100 nm wide) aligned in the plane of the ASI sample surface is shown. Likewise, using the example of a Ni-Mn-Ga magnetic shape memory alloy (MSMA), MFM is demonstrated in an inert atmosphere with magnetic phase sensitivity capable of resolving a series of adjacent magnetic domains each ~200 nm wide.

Magnetic force microscopy (MFM) employs a vertically magnetized atomic force microscopy probe to measure sample topography and local magnetic field strength with nanoscale resolution. Optimizing MFM spatial resolution and sensitivity requires balancing decreasing lift height against increasing drive (oscillation) amplitude, and benefits from operating in an inert atmosphere glovebox.

优化磁力显微镜分辨率和灵敏度，以可视化纳米级磁畴

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force ...