High-spatial-resolution surface-temperature mapping using fluorescent thermometry
High-spatial-resolution surface-temperature mapping using fluorescent thermometry
复制标题
DOI：
10.1002/smll.200700581
复制
发表时间：
2008-07-01
期刊：
影响因子：
13.3
通讯作者：
Bergaud, Christian
中科院分区：
文献类型：
--
作者：
Loew, Peter;Kim, Beomjoon;Bergaud, Christian
温度和热性能的表征在微纳米技术中尤为重要。考虑到小型化带来的结构密度和单位面积功耗的增加，良好的热设计对器件的可靠性和性能至关重要。定位热点，例如，在微电子电路上，可以在评估设计，优化性能和执行故障分析方面具有很大的价值。[1,2]除了微纳米尺度测温的工业应用之外，热行为的基本问题，例如与声子波长相当的尺度上的热传递，[3]可以通过改进的表征工具更有效地解决。在微观尺度上绘制温度图的常用方法是基于红外显微镜，它依赖于对任何材料发出的热辐射的分析。红外显微镜是一种成熟的技术，可以相对容易地用于大尺度的温度测绘。然而，该技术受到衍射分辨率的限制，其最佳空间分辨率约为5毫米[2,4,5]。纳米级科学家通常使用扫描热显微镜（SThM）进行高分辨率测量。自20世纪80年代初扫描探针显微镜发明以来，已经开发了几种用于热表征的扫描探针。所使用的热探头通常基于热电偶或热敏电阻元件。[7-11]其他方法提出用双材料悬臂或荧光粒子作为温度传感探针。[12-14]迄今为止，使用SThM获得的最高空间分辨率低于50nm.[7]扫描探头的主要缺点是读出速率慢。此外，探针必须与样品接触，从而在样品和SThM设备之间提供热桥。因此，测得的真实样品温度并不明显。文献中通常发现的其他测温技术依赖于拉曼光谱[15-17]和热效应显微镜。[18-21]两者都是非接触式和非侵入式技术，能够呈现亚微米级的空间分辨率。拉曼光谱非常适合于从室温到10008℃以上的大温度范围的表征。空间分辨率由其激光光斑直径决定，使用高倍率物镜，光斑直径可小至500nm虽然它能够在非常小的时间尺度上进行点测量，但图像的渲染速度很慢，因为它一次只能分析一个点，获取速度很慢，为0.5点sÀ1.[22]由于金属表面的低能声子模式，拉曼光谱不适合测量金属表面的温度。热效应显微镜的原理是任何材料的表面反射率都取决于它的温度。通过测量入射光的反射情况，可以提取温度信息。该方法既可以应用于扫描模式，也可以应用于全场模式。扫描模式提供了优越的温度分辨率，但读取速率较慢。热效应显微镜的主要缺点是其繁琐的校准过程。在大多数情况下，每种材料的热效应系数都是已知的，但在文献中并不容易得到。此外，反射特性对诸如照明波长等因素很敏感，在微电子器件的情况下，…
The characterization of temperature and thermal properties is of particular importance in micro-and nanotechnology. Considering the highly increased density of structures and the increased power dissipation per unit area associated with miniaturization, good thermal design is of great importance for device reliability and performance. Locating hot spots, for example, on a microelectronic circuit, can be of great value in evaluating a design, optimizing the performance, and performing failure analysis.[1, 2] Apart from the industrial applications of micro-and nanoscale thermometry, fundamental questions of the thermal behavior, for example, thermal transfer at a scale comparable to the phonon wavelength,[3] could be more effectively addressed with improved characterization tools. The common approach for mapping temperature on the microscale is based on infrared microscopy, which relies on the analysis of the thermal radiation that is emitted from any material. IR microscopy is a well-established technique and can be used with relative ease for temperature mapping on large scales. However, the technique suffers from a diffractionlimited resolution, giving it an optimal spatial resolution of around 5 mm.[2, 4, 5] Nanoscale scientists typically use scanning thermal microscopy (SThM) for high-resolution measurements. Since the invention of the scanning probe microscope at the beginning of the 1980s,[6] several scanning probes for thermal characterization have been developed. The thermal probes used are generally based on either thermocouple or thermistor elements.[7–11] Other approaches have proposed bimaterial cantilevers or ffuorescent particles as temperaturesensing probes.[12–14] The highest spatial resolution obtained to this date using SThM lies below 50nm.[7] The main drawback with the scanning probes is the slow readout rate. In addition, the probes have to make contact with the sample and thereby provide a thermal bridge between the sample and the SThM equipment. Therefore, it is not obvious that the true sample temperature is measured. Other thermometry techniques typically found in the literature rely on Raman spectroscopy [15–17] and thermoreffectance microscopy.[18–21] Both are noncontact and noninvasive techniques that are capable of rendering submicrometer spatial resolution. Raman spectroscopy is well suited for the characterization of large temperature ranges from room temperature up to above 10008C. The spatial resolution is determined by its laser spot diameter, which can be as small as 500nm using a high-magnification objective.[16] Although it is capable of point measurements at very small timescales, the rendering of images is slow as it analyses only one point at a time at a slow acquisition rate of 0.5 points sÀ1.[22] Due to the low-energy phonon modes of metallic surfaces, Raman spectra are not suitable for the measurements of temperature on metals. Thermoreffectance microscopy relies on the fact that the surface reffectivity of any material depends on its temperature. By measuring how incoming light is reffected, temperature information can be extracted. The method can be applied either in the scanning mode or in the full-field mode. The scanning mode provides a superior temperature resolution but suffers from a slower readout rate. The main drawback with thermoreffectance microscopy is its tedious calibration process. The thermoreffectance coefficient, which has to be known for each material, is not readily available in the literature in most cases. Furthermore, the reffectance properties are sensitive to factors such as the illumination wavelength and, in the case of microelectronic devices, the …