材料與材料分析(Materials and Materials Analysis): 材料分析Part B-1 原子力顯微鏡(AFM)

SPM(scanning probe microscope)是一群研究樣品表面性質(形態、磁性、電性、…….等等)的顯微鏡的總稱。在SPM族群中被應用最廣的是STM(scanning tunneling microscope)和AFM(atomic force microscope)，分析層次可從微米級至原子級。

Scanning probe microscope(SPM) is a terminology for a group of probing microscopes exploring properties, including morphology, magnetism, electric of top surfaces of materials. Scanning tunneling microscope(STM) and atomic force microscope(AFM) are the two most used. Their resolutions fall in the range of micrometer to atomic scale.

STM於1981年由IBM公司的Dr. Gerd Binning和Dr. Heinrich Rohrer共同發明。1986年兩人和Dr. Ernst Ruska(TEM發明人)共享諾貝爾物理獎。STM乃藉由探針尖端和試片的穿隧電流的變化，產生STM影像。STM的解析度可達0.1奈米，高解析STM通常必須在真空之中操作，樣品必須是導體。

STM was developed by IBM Dr. Gerd Binning and Dr. Heinrich Rohrer in 1981. They received Nobel Prize in Physics in 1986. STM images are formed by recording the variation of current which tunneled from the probe tip to the specimen surface during scanning. The resolution of STM can reach 0.1 nm. Usually, it is better to perform the scanning in an isolated vacuum chamber and use a conductive specimen to get resolution of atomic scale.

AFM則是藉由探針尖端和樣品表面的原子吸力或斥力的作用，使懸桿彎曲或偏折進而導致背面“鏡子”偏轉雷射光束到達PSPD的不同位置，電腦接收並分析4片光偵測器光訊號的變化，產生AFM 影像，如圖B-2所示。AFM 分析通常在空氣中進行，試片可以是非導體樣品，成為目前最方便，而且使用最廣泛的SPM。AFM有三種基本操作模式：接觸模式、不接觸模式、中間模式，對應的探針和試片位置如圖B-3所示。

AFM images are formed by using a position sensitive photodetector (PSPD) senses the variation of the laser beam which reflects from the back of the tip, as shown in Fig. B-1. AFM experiments are performed in air, and the specimen is not necessary to be conductive. This convenience makes AFM be the most popular in SPM family. There are three operation modes for AFM: contact mode, noncontact mode, and tapping mode, corresponding distance between tips and specimens are shown in Fig. B-2.

圖B-4展示一典型的AFM應用，光碟片記錄溝槽輪廓量測。圖B-4(a)局部CD的AFM俯視圖，圖B-4(b) (a)的3D立體圖，圖B-4(c) (a)中紅線位置的溝槽輪廓線。

Fig. B-4 displays a typical application of AFM, measurement of CD profiles. Fig. B-4(a) is a top view of part of CD, (b) is a 3D view of (a), and (c) is the profile of the position marked by the red line in (a).