We present a new quantitative method for investigating red blood cell morphology and dynamics. The instrument integrates quantitative phase microscopy with an inverted microscope, which makes it particularly suitable for the noninvasive assessment of live erythrocytes. In particular, we demonstrate the ability of this approach to quantify noninvasively cell volume and dynamic morphology. The subnanometer path-length sensitivity at the millisecond time scales is exemplified by measuring the hemoglobin flow out of the cell during hemolysis.
Using Hilbert phase microscopy, a technique recently developed in our laboratory, the nanometer level structure and dynamics associated with live red blood cells have been quantified on the 10 millisecond time scale.
Photomasks are currently inspected based on the standard of defect size. A shortcoming of this standard is that the type of defects which do not impact on a wafer, could be detected as impermissible defects. All of them are subject to repair works and some of them require further inspection by AIMS. This is one of the factors that are pushing down the yield and the turnaround time (TAT) of mask manufacturing. An effective way to improve this situation will be to do the repair works selectively on the defects that are predicted to inflict a functional damage on a wafer. In this report, we will propose a defect evaluation system named ADRES (Advanced Photomask Defect Repair Evaluation System), featuring a function to extract edges from a mask SEM image to be passed on to a litho-simulation. A distinctive point of our system is the use of a mask SEM image with a high resolution.
Tolerance-based process proximity correction (PPC) verification methodology is proposed for “hot spot management” in LSI fabrication process flow. This methodology verifies the PPC accuracy with the features of actual processed wafers/masks and target features in CAD data including CD tolerance around hot spots. The CD tolerance in CAD data is decided according to device characteristics, process integration, CD budget, and so on, and is used for the judgment criteria of the PPC accuracy. After the verifications, the actions in the manufacturing are decided. This methodology is demonstrated for the 65nm-node CMOS local metal at three representative hot spots extracted by lithography simulation, and the results yielded useful information for the manufacturing.
The measurement precision required for 65 nm technology node is 0.4 nm. However, ITRS has reported that the present CD-SEM has not had sufficient capability for 65 nm technology node. It is necessary to analyze the error factor of measurement precision thoroughly, in order to improve CD-SEM performance. Then, the items to be improved and the control method of tools for the measurement precision required for 65 nm technology node were examined. The error factors of CD measurement were divided into short-term repeatability, long-term variation, and tool matching. In factor analysis of short-term repeatability, the main factors of short-term repeatability were the image quality/measurement method and wafer load/unload. And it became clear that the interaction between local CD variation and scan shift accuracy had a remarkable effect on short-term repeatability. We established a method of monitoring tool condition in order to calculate long-term variation and tool matching with high accuracy. According to the experimental results of two tools for four weeks, the main factors of long-term variation and tool matching were initial variation and CD offset. From calculation of measurement precision using these results, measurement precision of the present CD-SEM has sufficient capability for hp90. It is reasonable to expect that improvement of these error factors will lead to the attainment of capability sufficient for hp65 measurement precision in the future.
A fine pixel CD-SEM system is developed. The convnetional CD-SEM Topcon MI-3080UR system consists of main body, 512 pixel SEM image acquisition system and 1D pattern size measurement system. The fine pixel CD-SEM system is added the conventional CD-SEM TOPCON MI-3080UR system. The fine pixel CD-SEM system consists of 2048pixel SEM image acquisition system is used by adjusting a novel measurement algorithm for the SEM image of 2D patterns. Firstly, the necessity of the fine pixel CD-SEM is discussed from the viewpoint of getting good repeatability of pattern size measurements. Effective factors causing the good repeatability for pattern size measurements are studied. The effective factors are mainly SEM image quality and pattern measurement algorithm. Secondly, repeatability of 2D pattern measurements by using the developed fine pixel CD-SEM image and the novel algorithm are evaluated. The evaluated 2D patterns are used for hammer head type OPC patterns for DRAM cell pattern. Finally, we investigate the usefulness of the fine pixel CD-SEM by usign the same novel algorithm for comparison of the conventional and the fine pixel CD-SEM.
A Novel model-based process proximity correction (PPC) verification methodology is proposed. This methodology features the comparison between actual processed wafers and target CAD data. The new system makes it possible to compare extracted two-dimensional pattern features on actual processed wafers with target pattern features on CAD data at any “hot spot” patterns. The “hot spot” patterns have relatively large CD errors on wafers after PPC in lithography simulation. In addition to this methodology, the model-based PPC verification flow was constructed with a feedback loop of the results. The application of this methodology to the 90nm-node CMOS gate yielded useful information on accurate CD control. The qualitative and quantitative consideration from the results indicated suitable subsequent actions regarding wafer fabrication, mask re-fabrication, PPC re-modeling and PPC re-parameterization in the feedback loop.
We have developed a new system, 'PF-3000', which realizes the pattern shape comparison between CAD layout data and CD-SEM images. Comparison results are expressed as the difference of edge location and area in this system. Moreover, we investigated different methods of shape comparison. Fourier descriptor is one of the most useful method.
Reducing resist thickness easily and simultaneously decreases the k1 factor and increases the k2 factor in conventional Rayleigh equations, without changing the wavelength of the illumination light and NA of the optics. In this work, we investigated the effect of reduced resist thickness on process latitude and optical proximity effect (OPE) at the sub-quarter micron level. The experiment exposures were performed by a 0.6 NA KrF excimer step and scan system with an in-house chemically amplified positive resist in the thickness range of 0.6 micrometers to 0.25 micrometers . The results showed remarkable improvements in process latitude of both 0.175 micrometers L&S and 0.225 micrometers contact hole, as well as OPE such as a CD variation between different pitches and a feature deformation at isolation by reducing resist thickness.