2007.8
About Instruments Today No. 159
Atomic Layer Deposition Technology and Applications
Atomic-Layer-Deposited High-κ Dielectrics Used as the Gate Oxides for the MOSFET Application [ 下載 PDF ]
Yan-Kai Chiou, Che-Hao Chang, Tai-Bor Wu
With the further shrinking of the MOSFET device dimension, the conventional SiO2 thin film as gate oxide reaches its limit. Replacement of SiO2 with other high-k dielectrics is the solution. Among the high-κ candidates, hafnium oxide (HfO2) has attracted much attention due to its suitable properties. On the other hand, atomic-layer-deposition (ALD) is an important method to deposit high-κ dielectrics due to its excellent thickness and uniformity control, as well as low-temperature deposition ability. In our work, we demonstrate the successful deposition of HfO2 thin films on the silicon substrate. Excellent thickness uniformity (STDEV (%) – 0.53%) on a four-inch-wafer range with a constant growth rate of ~0.95 nm/cycle was obtained. Besides, the satisfactory electrical properties of MOS capacitor with HfO2 as gate oxide were also obtained.
Design Concept and Applications of Atomic Layer Deposition System [ 下載 PDF ]
Chi-Chung Kei, Shiou-Fen Lin, Chien-Nan Hsiao
The atomic layer deposition (ALD) is carried out by using exchange reaction between precursor gas molecules and substrate. Good thickness uniformity in a large area and precise control in thickness and composition make atomic layer deposition become an enabling technology for the semiconductor industry. In this article, principle, development and design concept of ALD system will be given. Applications of ALD on semiconductor device, functional thin film and nanostructure coating will be introduced in detail.
The Application of Atomic Layer Deposition for the Growth of III-Nitrides [ 下載 PDF ]
Dong-Yuan Lyu, Tai-Yuan Lin, Jyh-Rong Gong
GaN-related group-III nitrides have been widely employed in the ultra high brightness blue, green, ultraviolet and white light emitting diodes (LEDs) because of several advantages including the nature of direct and wide bandgap, strong chemical bond and good radiation hardness. Recent advances of III-nitride LEDs have paved the way of solid state lightings with reduced energy consumption. Some people consider the III-nitride family as the most important semiconductor materials for the 21st century. Owing to the large lattice mismatch between GaN and sapphire (or Si) substrate, defects like dislocations (or cracks) may nucleate. As a result, the implementation of buffer layer is a good choice to accommodate the mismatch. Atomic layer deposition (ALD) has manifested itself as a potential technique for buffer layer deposition in highly mismatched heteroepitaxy because of its unique self-limiting kinetics. In this article we present the use of ALD for the growth of III-nitride buffer layers, superlattices and interlayer structures.
The Principles and Applications of Atomic Layer Deposition [ 下載 PDF ]
Yung-Huang Chang, Chih Chen, Chih-Lung Peng
Atomic layer deposition (ALD) has attracted a lot of attention recently for its excellent deposition abilities, such as almost 100% step coverage, accurate thickness control, large area uniformity, excellent process stability, and low processing temperatures. These excellent abilities can be contributed to the mechanism of saturated chemi-sorption and self-limiting film deposition, which differs from traditional deposition technology. In this report, the growth mechanisms of ALD, instrumentation, and applications are described in details.
Applications of Atomic Layer Deposition on Flexible Electronics [ 下載 PDF ]
Feng-Yu Tsai
Flexible electronics call for thin barrier/encapsulation films that can effectively prevent ambient H2O and O2 from getting contact with their organic active materials. Because of its unique advantages of low defect density, low deposition temperature, and 100% conformality, ALD presents the most promising solution among all current thin film deposition techniques for the encapsulation of flexible electronics. Previous studies have demonstrated that ALD Al2O3 films at 26-nm thickness yielded barrier performance on par with flexible electronics’ requirements, and the films’ barrier performance did not change upon repeated flexing to a curvature of 2-cm radius. Thinfilm encapsulation of OLED using ALD also showed orders-of-magnitude improvements over the state-of-the-art thin-film encapsulation processes. In terms ALD equipments, the flexible electronics applications call for designs that are different from those of the current off-the-shelf tools but that are likely simpler in many aspects, making the development of specialized ALD tools an ideal arena for Taiwanese equipment manufacturers.
Perpendicular Magnetic Media for 1 Tera bits/in2 and Beyond [ 下載 PDF ]
Meng-Shian Lin, Chien-Hsin Ho, Chih-Huang Lai
The recording density of HDD (hard disc drive) has increased 500,000,000 times since 1956. The superparamagnetic (SPM) effect, which may cause the loss of stored information, has been believed as a critical limitation for magnetic recording. In magnetic industry, SPM effect has promoted the perpendicular media in market to replace the conventional longitudinal media in 2006. To increase the recording density of HDD, the perpendicular recording provides a solution for future highdensity recording. The current perpendicular recording media just postponed the coming of the SPM effect. However, the problem becomes even severe for the development of ultrahigh recording density of 1 Tbit/in2, which requires each magnetic bit size smaller than 25 nm. In this article, we discuss the novel technology development of ultra-high-density magnetic media.
Non-Interferometric Widefield Optical Profilometry and Its Applications on the Research of Cell Dynamics [ 下載 PDF ]
Chun-Chieh Wang, Tsi-Hsuan Hsu, Jian-Long Xiao, Jiunn-Yuan Lin, Chau-Hwang Lee
Non-interferometric widefield optical profilometry (NIWOP) is a surface profilometry with nanometer depth resolution, which obtains surface topography without contacting and scanning the sample surface. NIWOP is also compatible with other optical contrast mechanisms. Therefore it is very suitable for the quantitative studies on cell membrane topography and cellular dynamics. In this article, we describe the principle and setup of the NIWOP technique. We also introduce the studies on membrane dynamics using this technique. Moreover, we employ a maximum-likelihoodestimation algorithm to improve the lateral resolution of NIWOP images. The super-resolution NIWOP images are used for the analyses of filopodium dynamics of cancer cells.
The Study for Applying Ultra-Precision Diamond Fly-Cutting Process to Develop the Micro Prism-Array Mold [ 下載 PDF ]
Ching-Hsiang Kuo, Wei-Yao Hsu, Fong-Zhi Chen, Yuan-Chieh Cheng, Wen-Lung Lin, Chien-Jen Chen
The micro prism-array is constructed by three isogonal V-groove arrays. The angle and surface finishing of V-groove are the key points of the retro-reflective efficiency. In general, V-groove could be fabricated by fly-cutting or scraping (grooving). In this study, we used the fly-cutting function of the ultra-precision freeform machine (Precitech FF705XG) to fabricate the micro prism-array mold. To get high retro-reflective efficiency of the micro prism-array, we analyzed the diamond tool angle error and assembly orientation error relative to the spindle rotation axis, and discussed fly-cutting process in detail including the cutting feed and spindle balancing issues.
Development and Applications of Polarization Near-Field Optical Microscopy [ 下載 PDF ]
Pei-Kuen Wei, En-Hong Lin, Shen-Yi Chiu
Polarization optical microscopy has been widely employed in studying the properties of crystalline domains. However, the optical diffraction limits its spatial resolution to submicron scale. On the other hand, scanning probe microscopy has nanometer spatial resolution. But it lacks optical information to distinguish the material properties. We develop new microscopes that combine the optical polarization and scanning probe microscopy. They can quantitatively study the organized domains with a resolution below 100 nm. In this article, two kinds of microscopes are introduced. One is the 'polarization-modulation near-field optical microscope' used for studying the organized domains in thin films. The other is the 'near-field magneto-optical microscope' used for studying submicron magnetic domains.
Strain Studies of Silicon-Germanium Hetero- Epitaxial Layer by X-ray Reciprocal Space Mapping [ 下載 PDF ]
Ming-Hsin Cheng, Hung-Min Lin, Eddy Jones
Recently, single crystal Si channels in metal-oxide-semiconductor field effect transistors (MOSFETs) have been replaced with stained Si, SiGe and Ge channels in order to enhance electron or hole mobility in channel direction. Therefore, it is a significant issue to evaluate the strain relaxation and lattice mismatch in these strained silicon-germanium hetero-epitaxial layers. However, two-dimensional reciprocal space mapping (2D-RSM) employing the triple axis X-ray diffractometry have been considered to be a powerful technology to characterize the strain status of these kinds of materials. In this article, we describe the principle of 2D-RSM, the optic components in triple axis X-ray diffractometry, experimental procedures in detail, the principle of strain calculation, and finally illustrate the experimental results of a variety of strained silicon-germanium hetero-epitaxial layers using two-dimensional reciprocal space mapping technology.
