Shin Usuki

Super-resolution optical inspection for semiconductor defects using standing wave shift

Semiconductor design rules and process windows continue to shrink, so we face many challenges in developing new processes such as 300mm wafer, copper line and low-k dielectrics. The challenges have become more difficult because we must solve problems on patterned and un-patterned wafers. The problems include physical defects, electrical defects, and even macro defects, which can ruin an entire wafer rather than just a die. The optics and electron beam have been mainly used for detecting of the critical defects, but both technologies have disadvantages. The optical inspection is generally not enough sensitive for defects at 100nm geometries and below, while the SEM inspection has low throughput because it takes long time in preparing a vacuum and scanning 300mm. In order to find a solution to these problems, we propose the novel optical inspecting method for the critical defects using standing wave shift. This method is based on a super-resolution algorism in which the inspection systems resolution exceeds the diffraction limit by shifting standing wave with the piezoelectric actuator. Additionally this method is optical one, so we can expect to develop high throughput inspection system. In this report, we performed theoretical discussions and computer simulations the defect detection on a patterned wafer. As a result, we succeeded in detecting the critical defects in the sub-90nm line and space interconnections.

Variational formulation of the log-aesthetic curve

The log-aesthetic curves include the logarithmic (equiangular) spiral, clothoid, and involute curves. Although most of them are expressed only by an integral form of the tangent vector, it is possible to interactively generate and deform them and they are expected to be utilized for practical use of industrial and graphical design. We reformulate the LA curve with variational principle in order to analyze its properties.

Development of super-resolution optical inspection system for semiconductor defects using standing wave illumination shift

Semiconductor design rules and process windows continue to shrink, so we face many challenges in developing new processes such as 300mm wafer, copper line and low-k dielectrics. The challenges have become more difficult because we must solve problems on patterned and un-patterned wafers. The problems include physical defects, electrical defects, and even macro defects, which can ruin an entire wafer rather than just a die. The optics and electron beam have been mainly used for detecting of the critical defects, but both technologies have disadvantages. The optical inspection is generally not enough sensitive for defects at 100nm geometries and below, while the SEM inspection has low throughput because it takes long time in preparing a vacuum and scanning 300mm. In order to find a solution to these problems, we propose the novel optical inspecting method for the critical defects on the semiconductor wafer. It is expected that the inspection systems resolution exceed the Rayleigh limit by the method. Additionally the method is optical one, so we can expect to develop high throughput inspection system. In the research, we developed the experimental equipment for the super-resolution optical inspection system. The system includes standing wave illumination shift with the piezoelectric actuator, dark-field imaging and super-resolution-post-processing of images. And then, as the fundamental verification of the super-resolution method, we performed basic experiments for scattered light detection from standard particles.

Theoretical and numerical analysis of lateral resolution improvement characteristics for fluorescence microscopy using standing evanescent light with image retrieval

This paper presents a lateral resolution improvement for TIRF (total internal reflection fluorescence) microscopy that employs a combination of standing evanescent light and a fluorescence distribution retrieval algorithm with successive approximation. In this method, variations in fluorescence images are detected by shifting the standing evanescent light illumination. Lateral resolution improvement beyond the diffraction limit can be achieved by using multiple fluorescence images. In this paper, the expression of lateral resolution improvement based on the Rayleigh criterion was theoretically formulated from the aspect of Fourier optics. This derived formula and numerical simulations indicate that the proposed method has about twice the resolution of conventional optical microscopy and under 100 nm resolution is achievable even in the case of the long working distance condition. For the special specimen consisting of the discrete distribution, the proposed method has more resolving power beyond the optical spectrum limit extended by the structured illumination of the standing evanescent light by performing its position shift over the peak-to-peak distance of the illumination distribution.

Reformulation of Generalized Log-aesthetic Curves with Bernoulli equations

AbstractA recent research has found out the relationship between the Log-aesthetic Curve and Riccati differential equations. The obtained differential equations are Riccati, but also Bernoulli type. Based on Sato and Shimizus derivation of the formula of ρ-shift generalized log-aesthetic curve (GLAC), we derive the formula of the κ-shift GLAC as a solution of a Bernoulli differential equation.

The Polar-aesthetic Curve and Its Applications to Scissors Design

ABSTRACTThe origin of scissors is very old and a pair of scissors which was probably made in ancient Greece around B.C. 1000 is discovered. In Japan a new type of scissors was produced with newly designed blades and has become one of hit products in 2012. The shape of their blades is a Bernoulli curve. The Bernoulli curve is the logarithmic spiral and can be classified as a type of the log-aesthetic curves. One of its properties is that the angle between its tangent vector and the radial axis from the origin is kept constant. This is the reason why the logarithmic spiral is also called the equiangular spiral. Consequently if the blades of a pair of scissors are given by a logarithmic spiral, the cutting angle is always constant.In this paper, we extend the logarithmic spiral to make the cutting angle of a pair of scissors a linear function of the rotation angle of the cutting edges and newly define the polar-aesthetic curve and discuss about conditions for the monotonicity of its curvature. Furthermore we...

Minimum Variation Log-aesthetic Surfaces and Their Applications for Smoothing Free-form Shapes

Abstract The log-aesthetic curve, which includes the logarithmic (equiangular) spiral, clothoid, and involute of a circle, achieves a control over curvature distribution by defining its shape as an integral form of its curvature and they are expected to be utilized for the field of design. However, it is very difficult to extend it to surfaces and the existing formulations have some problems that they cannot use arbitrary boundary curves. In this paper, we propose “minimum variation log-aesthetic surface” as a new formulation for the log-aesthetic surface. Based on variational principle our method can generate surfaces by minimizing the objective function newly proposed in this paper for given arbitrary boundary curves.

Log-aesthetic flow governed by heat conduction equations

ABSTRACTIn this research, based on the concept of the smoothing by curve shortening flow and curvature flow, we will propose log-aesthetic flow to make free-form curves “log-aesthetic.” We will discuss smoothing methods that deal with continuous curves as well as discrete ones. We have one degree of freedom to control smoothing for log-aesthetic flow and can expect the completely smoothed shape of a given curve, which means the shape obtained by fairing, to be log-aesthetic curve. This paper shows that log-aesthetic flow is basically governed by the heat conduction equation, which has been well studied in both physics and mechanical engineering, its effects are easily inferred by the designers and it will be useful for practical aesthetic design.

Forming intermediate spatial resolution of microscopy images for continuous zooming on multi-resolution processing system

Digital zooming especially on microscopy image has attempted to improve their quality of measurement into a better assessment. However, since the field of view of high-resolution image are not wide despite of the fact that high-resolution image has more information detail and low-resolution image has their merits which is bring a big picture of the whole structure, we need to observe the sample in any scale. This problem was been solved by developing dual-view of high and low images resolution1 but in a single interpolated images. The goal of this research is utilize multi-resolution images to develop smooth zooming magnification of microscopy image. In order to achieve smooth zooming magnification on different condition of the images, scheme process will be needed. First, we took a several spatial images of the same sample based on the different objective lens, author was used 4 objective lens which are 10×, 20×, 50× and 150× magnification. In this synthesize phase, we interpolate lower resolution image for synthesize purpose with the next higher resolution image of the sample. Second, continue to looking for the feature point of both images with SIFT feature point method until we synthesize both images. Third, author treat this synthesized image with discrete fourier transform (DFT) with low-pass filter as the same size with numerical aperture (NA) that was input on the first phase. Then the fourth phase is looping this processes until intermediate images are generated enough to be blend with pyramid blend method. In this article we also try to make a system that can arbitrarily generate intermediate image with hierarchical system.

Nano-Micro Geometric Modeling Using Microscopic Image

In recent years, there are a lot of active researches on nano-micro manufacturing and metrology, since not only industrial fields but also medical fields require higher accuracy with respect to miniaturizing size of the target. However, we cannot make an effective use of three dimensional measurement data for the nano-micro design and manufacturing due to a wide variety of instruments, resolutions, and noises. In fact, the nano-micro geometric modeling is at an early stage of development in spite of its importance for the next generation. In order to find a solution to this problem, we propose to combine the multi-resolution processing with the microscopic images for high speed and non-destructive geometric modeling as well as for the homogeneous modeling from micro features to macro ones. This research includes measurement data tiling between different instruments, high resolution optical microscopic imaging, focus judgment of three dimensional microscopic data, and large scale point crowd processing. These built models are potentially applied to in-line inspections and numerical simulations. Therefore, the nano-micro geometric modeling contribute to further developments of ultra precise manufacturing and the biotechnology.