Prediction of Residual Stress Distribution in Multi-Stacked Thin Film by Curvature Measurement and Iterative FEA

Choi Hyeon Chang,Park Jun Hyub The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.5

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method (FEM). We evelop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi­stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multi layers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.

Anisotropic, non-uniform misfit strain in a thin film bonded on a plate substrate

Huang, Y.,Ngo, D.,Feng, X.,Rosakis, A.J. Techno-Press 2008 Interaction and multiscale mechanics Vol.1 No.1

Current methodologies used for the inference of thin film stresses through curvature measurements are strictly restricted to stress and curvature states which are assumed to remain uniform over the entire film/substrate system. These methodologies have recently been extended to non-uniform stress and curvature states for the thin film subject to non-uniform, isotropic misfit strains. In this paper we study the same thin film/substrate system but subject to non-uniform, anisotropic misfit strains. The film stresses and system curvatures are both obtained in terms of the non-uniform, anisotropic misfit strains. For arbitrarily non-uniform, anisotropic misfit strains, it is shown that a direct relation between film stresses and system curvatures cannot be established. However, such a relation exists for uniform or linear anisotropic misfit strains, or for the average film stresses and average system curvatures when the anisotropic misfit strains are arbitrarily non-uniform.

ANALYSIS OF CHANGHWA HONGNYŎN (A TALE OF TWO SISTERS)—WITH A SPECIAL FOCUS ON THE NARRATIVE AND CHARACTERS

서정남 계명대학교 한국학연구원 2011 Acta Koreana Vol.14 No.1

This study analyzes the story structure of director Kim Chiun’s film Changhwa Hongnyŏn (A Tale of Two Sisters), as well as the characters that arouse, lead, and complete the events that unfold in the story. While eight years have already passed since its release, this film continues to serve not only as the subject of many studies conducted by researchers involved in the field of film studies but also those engaged in the field of literary studies. To this end, this study begins by reviewing the opinion pieces written by film critics, pieces which caused much debate in fan magazines at the time of the film’s release, as well as the great majority of the previous studies that have focused on this film. Many individuals have conducted comparative studies about the direct and indirect relationship between the classic novel Changhwa Hongnyŏn chŏn and the film Changhwa Hongnyŏn. Such studies have focused on how the film adapted and transformed the classic novel, or how far the film deviated from the original work. However, these issues were not addressed in this study. This is because it is advanced herein that from the very beginning Kim’s decision to entitle his film Changhwa Hongnyŏn was based on a heavily calculated strategy that did not involve any intention to inherit or adapt (translate) any element of the original story in the film. The second issue which came to the forefront during the review of previous studies was the fact that the majority of researchers had a negative assessment of the film narrative’s degree of completion. In this regard, the present study conducted a thorough segmentation-based analysis of the text that saw the temporality and causal relationships found in the story be reorganized in a logical manner. The narrative structure of the film was also delved into in a detailed manner. Next, an analysis of the relationship between the characters and their personalities was undertaken. The dramatic relationship that exists between the characters was explained using the summary found in Figure 1. Thereafter, an analysis of the key characters, namely Sumi who serves as the film’s main character, and Muhyŏn (father), who serves as the cause of all the events that unfold therein, was carried out. An analogical examination of the elements which caused Sumi’s mental illness was also undertaken. Based on this process, the originality of Sumi’s complex ambivalence and how this ambivalence was expressed are clearly revealed. In the concluding section, the symbolism of the house as the background (space) for this film and its connectivity with the narrative was addressed. While the film does not suggest any alternative measures concerning the tragic situations that have been unlimitedly repeated inside of Sumi’s head, the present study does suggest that Sumi’s physical and mental departure from the house mark the first step towards overcoming her illness.

Substrate-dependent Internal Stress of Aluminum-doped Zinc-oxide Thin Films Deposited by DC Magnetron Sputtering

김태원 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.4

The internal stress of very thin (30 nm) aluminum-doped zinc-oxide (AZO) films deposited by DC magnetron sputtering at room temperature was found to be strongly substrate dependent. The stress of an AZO film deposited on a single-crystalline Si wafer substrate changed more steeply than that of a film deposited on an amorphous glass substrate as deposition conditions, such as the sputter working pressure and the applied power on the cathode, were varied. This result can be explained by the atomistic peening effect which occurs more intensively in a more crystalline microstructure. Thus it can be inferred that the crystallinity of the substrate influences that of the growing film. In other words, the more crystalline the substrate is, the more crystalline the growing film is. Support for this point of view was supplied by the X-ray diffraction pattern result showing that the intensity of the (002) plane diffraction peak for the AZO film grown on a Si wafer was higher than that for an AZO film grown on glass. That is, the AZO film grown on a crystalline Si wafer is more crystalline than the AZO film grown on an amorphous glass wafer. This study confirmed that the substrate influenced the internal stress of the growing film strongly.

Stress relaxation and transitions in optical bandgap of yttrium doped zinc oxide (YZO) thin films

Narinder Kaur,Sanjeev K. Sharma,Deuk Young Kim 한국물리학회 2016 Current Applied Physics Vol.16 No.3

The stress relaxation and its effect on the bandgap of Y-doped ZnO (YZO) thin films were investigated by thermal annealing. YZO thin films were prepared on quartz glass by spin coating and subsequent annealed in vacuum. All the annealed YZO films showed a preferred (002) orientation. Photoluminescence (PL) provides the direct evidence of shifting the bandgap owing to stress release phenomena. The shifting in bandgap by increasing the annealing temperature can be attributed to the stress relaxation of YZO thin films. The bandgap of annealed films was initially decreased due to increase in magnitude of compressive stress and then increased as the tensile stress induced in the films. Therefore, these results may suggest the way to tune the band gap of YZO thin films by varying the residual stress through annealing.

Effect of UV-ozone treatment on the bias-stress stability of indium-zinc-oxide thin-film transistors fabricated by using a sol-gel process

Ho Yong Chong 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.6

Thin film transistors (TFTs) with indium-zinc-oxide (IZO) channel layers were fabricated by using a solution process. The channel and the SiO2 insulator layers were exposed to ultraviolet (UV)-ozone to investigate the effect of UV-ozone treatment. The enhancement of the subthreshold slope of the UV-ozone-treated TFTs was dominantly attributed to a decrease in the defect density and an increase in the adhesion due to the ozone treatment on the SiO2 insulator layer. The positive-bias temperature stress results for the UV-ozone-treated IZO thin film showed that the threshold voltage shift and the subthreshold slope variation of the TFTs with an UV-ozone-treated IZO thin film were smaller than those with an as-deposited IZO thin film, indicative of an enhancement in the bias-stress stability. X-ray photoelectron spectroscopy spectra showed that the number of the oxygen vacancies and the number of trap sites for the as-deposited IZO film were larger than those of the UVozone-treated IZO film.

구리 박막 제조중 증착 중단시 박막 결정립 크기 변화가 인장응력 방향으로의 응력 이동에 미치는 영향

이세리(Seri Lee),오승근(Seungkeun Oh),김영만(Youngman Kim) 한국표면공학회 2014 한국표면공학회지 Vol.47 No.6

In this study, the average in-situ stress in metallic thin film was measured during deposition of the Cu thin films on the Si(111) wafer and then the phenomenon of stress shift by the interruption of deposition was measured using Cu thin films. We have observed the stress shift in accordance with changing amount of atom"s movement between the surface and grain boundary through altering the grain size of the Cu thin film with variety of parameters. The grain size is known to be affected on the deposition rate, film thickness and deposition temperature. As a experimental results, the these parameters was not adequate to explain stress shift because these parameters affect directly on the amount of atom"s movement between the surface and grain boundary as well as the grain size. Thus, we have observed the stress shift toward tensile side in accordance with the grain size changing through the interlayer deposition. From an experiment with inserting interlayer before deposit Cu, in thin film which has big grain size with high roughness, amount of stress movement is higher along direction of tensile stress after deposition that means, after deposition process, driving force of atoms moving in grain boundary and on the surface of the film is relatively higher than before.

Chloride Bath로부터 전기도금된 나노결정립 니켈 박막의 잔류응력 변화에 대한 연구

박덕용,Park, Deok-Yong 한국전기화학회 2011 한국전기화학회지 Vol.14 No.3

첨가제 농도, 전류밀도, 도금용액 pH가 Ni 박막의 잔류응력, 표면형상, 미세조직에 미치는 영향을 관찰하기 위하여 chloride 도금용액으로부터 나노결정립 Ni 박막이 제조되었다. Ni 박막에서 잔류응력은 첨가제인 saccharin의 농도가 증가함에 따라 인장응력모드(약 150 MPa)로부터 압축응력모드(약 -100 MPa)로의 천이가 관찰되었다. Ni 박막의 미세구조는 도금용액 내에 saccharin의 유무에 따라 변화되었다. Saccharin이 첨가되지 않은 도금용액으로부터 전기도금된 Ni 박막은 주로 FCC(111) 과 FCC(200) 상들로 구성되어 있다. 그러나 Saccharin이 첨가된 도금용액으로부터 전기도금된 Ni 박막은 FCC(111), FCC(200), FCC (311) 상[때로는 FCC (220)]들로 구성되어 있다. 전류밀도는 Ni 박막의 잔류응력에 영향을 미치는 것으로 관찰되었다. $2.5\sim2.5{\mu}10mA{\cdot}cm^{-2}$의 전류밀도에서 가장 낮은 압축응력 값(약 -100 MPa)을 나타내었다. 도금용액의 pH 도 역시 Ni 박막의 잔류응력에 영향을 미쳤다. 한편, 도금용액에 saccharin의 첨가는 Ni 박막의 결정립 크기에 영향을 나타내었다. Saccharin이 첨가되지 않은 경우 Ni 박막의 결정립 크기가 약 60 nm로 측정되었으며, saccharin 함량이 0.0005 M 이상 첨가된 경우 Ni 박막의 결정립 크기가 24~38 nm로 측정되었다. Ni 박막의 표면 형상은 saccharin이 첨가됨에 따라 nodular 형상으로부터 매끄러운 (smooth) 형상으로 변화되었다. Nanocrystalline Ni thin films were electodeposited from chloride baths to investigate the influences of additive concentration, current density and solution pH on residual (or internal) stress, surface morphology, and microstructure of the films. It was observed that residual stress in Ni thin film was changed from tensile stress mode (about 150 MPa) to compressive stress mode (about -100 MPa) with increasing saccharin concentration as an additive. Microstructure of Ni thin films was changed with/without saccharin in baths. Ni thin films electrodeposited from saccharinfree bath mainly consisted of both FCC(111) and FCC(200) phases. However, Ni thin film electrodeposited from the baths containing saccharin exhibited FCC(111), FCC(200) and FCC (311) phases [sometimes, FCC (220)]. Current density influenced residual stress of Ni thin films. It was measured to be the lowest compressive stress value (about-100 MPa) in range of current density of $2.5\sim10mA{\cdot}cm^{-2}$. Solution pH also influenced residual stress of Ni thin film. Addition of saccharin in baths affected grain size of Ni thin films. Grain sizes of Ni thin films were measured to be about 60 nm without saccharin and 24~38 nm with more than 0.0005M saccharin concentration. Surface of Ni thin films was changed from nodular to smooth surface morphology with addition of saccharin.

파워 필름 부착과 인장축 방향 변화에 따른 스포츠웨어용 트리코의 인장특성

최지영,홍경희,Choi, Jiyoung,Hong, Kyunghi 한국섬유공학회 2012 한국섬유공학회지 Vol.49 No.4

For the optimum performance of compression sportswear, tensile properties of base tricot and power film should be understood in the viewpoint regarding the use condition. However, it is difficult to predict the tensile properties of film-welded tricot, solely from the tensile information of the single layer of tricot or power film itself, especially when the direction of the power film does not follow the wale or course direction of the tricot, which often occurs in the actual design of performance sportswear. In this study, changes in the tensile properties of tricot, power film and film-welded tricot were investigated as the angle of tensile axis and the direction of welding varies from$0^{\circ}$ to $90^{\circ}$. Stress, initial modulus, and tensile energy were obtained up to 33~50% of the extension level, which is often observed in actual use. Results indicate that the area of power film matched to the tensile axis and width of power exertion is the key factor of tensile properties explaining stress, initial modulus and energy required during extension. Moreover, the results obtained in this study can be utilized in the arrangement of pattern piece for tricot and the positioning of power film to achieve the right support and extension level during body movement.

열 필라멘트 CVD법에 의해서 제작한 다이아몬드 막의 잔류응력제어

최시경,정대영,최한메 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.7

The relaxation of the intrinsic stresses in the diamond films fabricated by the hot filament CVD was studied, and it was confirmed that the tensile intrinsic stresses in the films could be controlled without any degradation in the quality of the diamond films. The tensile intrinsic stresses in the films decreased from 2.97 to 1.42 GPa when the substrate thickness increased from 1 to 10mm. This result showed that the residual stress was affected by the substrate thickness as well as by the interaction between grains. Applying of +50 V between the W filament and the Si substrate during deposition, the tensile intrinsic stress in the film deposited at 0 V was decreased from 2.40 GPa to 0.71 GPa. Such large decrease in the tensile intrinsic stress was due to $\beta$-SiC which acted as a buffer layer for the stress relaxation. However, the application of the large voltage above +200V resulted in the change of quality of the diamond film, and nearly had no effect on relaxation in the tensile intrinsic stress.