• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1065-1071
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• 2005

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.

• 열처리공학회지
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• 제6권2호
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• pp.70-78
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• 1993

The presence of a residual stress in a thin film affects the properties and performances of the film, so the study of stress in a film must be very important. In this study, therefore, considering the characteristics of PECVD process, it was discussed that the residual stress, measured by $sin^2{\Psi}$ method, fo TiN films deposited on substrates with different TECs (thermal expansion coefficients) changed with film thickness. As a results, it was obtained that the residual stress of TiN film was compressive stress about all kinds of substrates and increased with film thickness. Also, the compressive residual stresses of TiN films increased in Si, Ti, STS304 order. According to the above results, we confirmed that the changes of residual stress of TiN film with substrates were due to the thermal stress originated form the difference in the TECs of the film and substrates, and that the intrinsic stress had dominating effect on the residual stress of TiN film deposited by PECVD. And in this study, the intrinsic stress of TiN film was compressive stress in spite of the Zone 1 structure. It is due to the entrapment of impurities in grain boundary or void.

• 한국표면공학회지
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• 제44권4호
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• pp.137-143
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• 2011

The internal stress and magnetic properties (coercivity and squareness) of Ni-Fe nano thin film synthesized by electrodeposition method were studied as a function of acidic chloride bath conditions (composition and temperature) and current density. Fe deposition patterns were different depending on the temperature of the solution, the stress of film decreased with increasing the solution temperature, and the depending on the amount of Fe deposition showed a parabolic shape. The grain size of film was inversely proportional to stress of thin film. The internal stress of thin film and magnetic properties were deeply relevant, and the stress of thin film had a relationship with bath conditions and grain size of the thin film surface.

• 한국재료학회지
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• 제1권1호
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• pp.46-53
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• 1991

반도체 공정의 최종 보호막으로 주로 사용되는 PSG (Phosphosilicate class), USG (Undoped silicate glass) 및 SiN 막을 CVD 방식으로 deposition 하여 각 막의 스트레스를 막 두께 또는 대기중 방치시간의 함수로 조사하고 Al 배선의 stress-migration 관점에서 평가했다. 그 결과 PSG 막과 USG 막은 tensile stress를 나타내고 두께증가에 따라 스트레스가 증가하였고, SiN 막은 두께에 관계없이 일정한 compressive stress를 나타내었다. PSG 막은 현저한 스트레스 경시변화를 보여 대기중에 방치시 2일이내로 tensile stress가 compressive stress로 변화되었다. 그 주 원인은 PSG 막의 수분 흡수 때문인것이 FTIR 분석으로 밝혀졌고, $300^{\circ}C$에서 20분간 anneal 처리로 $2.5{\times}{10^9}\;dyne/cm^2$의 스트레스 회복이 가능하였다. PSG 막이 포함된 복합막의 경우, 복합막 stress는 PSG 막의 방치시간에 따라 변한다. 즉, 복합막의 스트레스는 복합막을 구성하고 있는 막들의 두께의 함수이다. 또 SiN 막의 강한 압축응력을 완화시켜주는 PSG, USG 막의 스트레스가 큰 인장응력을 나타낼수록 Al 배선의 stress-migration 에 대한 저항은 커진다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.237-242
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• 2001

Residual stress is a dominant obstacle to efficient production and safe usage of products by reducing the mechanical strength and failure properties. Especially, it causes interfacial failure and substrate deflection in the case of thin film. So, the exact evaluation and optimum control of thin film residual stress is indispensable. However, hole drilling or X-ray diffraction techniques have some limits in application to thin film. And, curvature technique for thin film materials cannot give the information about local stress variation. Therefore, we applied the nanoindentation technique in evaluating the thin film residual stress. In this study, we modeled the change of indentation loading curve for residually stressed and stress-free thin films during stress relaxation. The value of residual stress was directly related to the indentation depth change by relaxation. The residual stress from nanoindentation analysis was consistent with the result from curvature technique.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1270-1279
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• 2002

Residual stress is a dominant obstacle to efficient production and safe usage of device by deteriorating the mechanical strength and failure properties. Therefore, we proposed a new thin film stress-analyzing technique using a nanoindentation method. For this aim, the shape change in the indentation load-depth curve during the stress-relief in film was theoretically modeled. The change in indentation depth by load-controlled stress relaxation process was related to the increase or decrease in the applied load using the elastic flat punch theory. Finally, the residual stress in thin film was calculated from the changed applied load based on the equivalent stress interaction model. The evaluated stresses for diamond-like carbon films from this nanoindentation analysis were consistent with the results from the conventional curvature method.

• 한국정밀공학회지
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• 제20권9호
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• pp.135-141
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• 2003

MEMS structures generally have been fabricated using surface-machining method, but the interface failure between silicon substrate and evaporated thin film frequently takes place due to the residual stress inducing by the applied the various loads. And the very important physical property in the heated environment is the linear coefficient of thermal expansion. Therefore this paper studied the residual stress caused the thermal loads in the thin film and introduced the simple method to measure the trend of the residual stress by the indentation. Specimens were made of materials such as Al, Au and Cu and thermal load was applied repeatedly. The residual stress was measured by nano-indentation using AFM and FEA. The existence of the residual stress due to thermal load was verified by the experimental results. The indentation length of the thermal loaded specimens increased minimum 11.8％ comparing with the virgin thin film caused by tensile residual stress. The finite element analysis results are similar to indentation test.

• 반도체디스플레이기술학회지
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• 제3권2호
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• pp.35-40
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• 2004

The total relaxed stress in annealing and the thermal strain/stress were obtained from the identification of the residual stress-free state using electronic speckle pattern interferometry (ESPI). The residual stress fields in case of both single and film / substrate systems were modeled using the thermo-elastic theory and the relationship between relaxed stresses and displacements. We mapped the surface residual stress fields on the indented bulk Cu and the 0.5 $\mu\textrm{m}$ Au film by ESPI. In indented Cu, the normal and shear residual stress are distributed over -1.7 GPa to 700 MPa and -800 GPa to 600 MPa respectively around the indented point and in deposited Au film on Si wafer, the tensile residual stress is uniformly distributed on the Au film from 500 MPa to 800 MPa. Also we measured the residual stress by the x-ray diffractometer (XRD) for the verification of above residual stress results by ESPI...

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.395-398
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• 2000

Reactive radio frequency (RF)magnetron sputter with incident angle has been used to deposit AlN thin film on a crystalline Si substrate. (002)Preferred orientation of AlN thin film has been obtained at low sputtering pressure. Also it has been shown that depostion rate of AIN thin film is affected by fraction Ar and $N_2$ partial pressure. But substrate temperature didn't affect depostion rate of AIN thin film . As sputtering pressure increased preferred orientation degraded. The internal stress changed from tensile stress to compressive stress as fraction of $N_2$ partial pressure increased. At low nitrogen partial pressure cermet$^{[1]}$ AIN thin film is obtained.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.8-13
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• 2020

IC 패키지와 같이 두께가 수백 마이크로미터 정도로 매우 얇은 기판에서 뒤틀림 불량을 일으키는 가장 큰 원인은 응력이다. 일반적으로 응력은 기판 위에 서로 다른 물질을 적층할 때, 결정구조 및 그에 따른 열팽창 계수의 차이로 인해 발생한다. 본 연구에서는 사각형의 박막 패턴이 적층된 기판에 발생하는 응력의 거동을 수치적으로 분석하였다. 먼저 기판 변위를 구하고, 이를 이용하여 기판 변형률과 응력을 구하였다. 박막 패턴의 가장자리에 인장력이 집중된 경우, 박막 패턴의 가장자리를 중심으로 수직 응력과 전단 응력이 발생한다. 수직 응력은 박막 패턴의 가장자리와 꼭짓점 부근에 발생한다. 전단 응력도 박막 패턴의 가장자리를 중심으로 발생하나 수직 응력과는 달리 꼭짓점 부근에는 나타나지 않는다. 또한 가장자리를 중심으로 전단 응력의 크기와 방향이 바뀌는 것을 확인할 수 있었다. 박막패턴 가장자리 힘이 동일할 때, 수직 응력은 전단 응력에 비해 10배 정도의 값을 나타내었다. 이는 뒤틀림 불량을 일으키는 가장 큰 원인이 수직 응력임을 나타낸다.