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To clarify whether pattern waviness due to line-edge-roughness enhances wiggling, distortion of straight and wavy patterns was numerically analyzed by the three-dimensional (3D) elastic finite element method. Wiggling occurs only in wavy patterns but not in straight patterns at a stress or aspect ratio much lower than their buckling thresholds. More severe wiggling occurs when the wavelength of initial waviness approaches a value that is 3.3 times the pattern height. These phenomena were experimentally confirmed in the etching of amorphous carbon with a SiON mask. We consider that precise etching without wiggling is achieved by the elimination of the original line-edge roughness and the reduction in mechanical stress in an underlying film to which the pattern is transferred.

Section: D Linear Fem Buckling Analysismentioning

confidence: 99%

“…The causes of such stress have therefore been investigated. [3][4][5][6][7] Few studies, however, have discussed the changes in the amplitude and wavelength of wiggling due to pattern shape, 7,8) and none of them have focused on of the changes due to mask waviness caused by LER.…”

Section: Introductionmentioning

confidence: 99%

Line-edge roughness increase due to wiggling enhanced by initial pattern waviness

Kofuji

Negishi

Ishimura

et al. 2014

“…It has been reported that the wiggling occurs due to the bending of fine patterns by simulation using the finite element method (FEM). 5,[9][10][11] The bending is caused by material-specific mechanical properties such as Young's modulus and Poisson's ratio, pattern dimensions, and residual stress. 6,11) The thin film material formed on the substrate generates thermal stress due to a difference in the linear expansion coefficient from the substrate and internal stress due to distortion during film formation.…”

Section: Introductionmentioning

confidence: 99%

Stress evaluation induced by wiggling silicon nitride fine pattern using Raman spectroscopy

Koharada

Yokogawa

Sawamoto

et al. 2020

We evaluated the residual stress of the silicon nitride (SiN) fine pattern structure in order to quantitatively predict the occurrence of wiggling, which causes device failure. UV Raman spectroscopy showed an increase of tensile stress in Si substrate with increasing etching time, and the tensile stress in Si substrate was caused by the enhancement at the very edge of the fine pattern and the increase in the amount of over-etching. It was also confirmed that the edge enhanced effect can be obtained by using a UV laser for fine patterns, so that the Raman intensity from Si (amorphous and crystal) increased significantly with the etching time of the pattern. Furthermore, using water-immersion Raman spectroscopy, we evaluated the anisotropic biaxial stress applied to the fine patterns and showed occurrence of strain relaxation. The wiggling, therefore, occurs due to the huge anisotropic stresses induced in the Si substrates.

“…As pattern width decreases, however, the ACL masks have frequently been observed to collapse in a zigzag manner. [2][3][4][5][6][7][8] This type of collapse is called "wiggling" and hinders precise fabrication. Wiggling is known to be a type of pattern deformation caused by compressive stress.…”

Section: Introductionmentioning

confidence: 99%

“…Wiggling is known to be a type of pattern deformation caused by compressive stress. [4][5][6][7][8] The causes of such stress have therefore been investigated. Some studies have revealed that the internal residual stress in ACL increases owing to its fluorination after fluorocarbon plasma exposure during SiO 2 etching with an ACL mask.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of wiggling enhancement due to HBr gas addition during amorphous carbon etching

Kofuji

Ishimura

Kobayashi

et al. 2015

The effect of gas chemistry during etching of an amorphous carbon layer (ACL) on wiggling has been investigated, focusing especially on the changes in residual stress. Although the HBr gas addition reduces critical dimension loss, it enhances the surface stress and therefore increases wiggling. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the increase in surface stress was caused by hydrogenation of the ACL surface with hydrogen radicals. Three-dimensional (3D) nonlinear finite element method analysis confirmed that the increase in surface stress is large enough to cause the wiggling. These results also suggest that etching with hydrogen compound gases using an ACL mask has high potential to cause the wiggling.