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As the design rule becomes continuously smaller, the Hard OPC is being applied to pattern design in semiconductor production. Controllability of hard OPCed pattern’s quality directly affects to the performance of the device and yields of production. Critical Dimension Scanning Electron Microscopy (CD-SEM) is used to accurately confirm the Critical Dimension (CD) quality of the photomask. CD-SEM makes the pattern’s shape image by using secondary electrons information directly from the Mask surface and can measure CD values. Classically the purpose of CD-SEM measurement was to get one dimensional CD values. However it is difficult to guarantee complex hard OPCed pattern’s quality by using only one dimensional CD values because complexity of pattern design has been increased. To confirm and control the quality of hard OPCed pattern, the quality of pattern fidelity must be measured quantitatively. In order to overcome this difficulty we developed a new method to quantitatively evaluate the quality of pattern fidelity using EPE (Edge Placement Error) distance from the overlay between Target Design GDS and SEM GDS contour which is extracted from CD-SEM image. This paper represents how to define and analyze quantitatively the quality of complex hard OPCed pattern.

The 1Xnm technology node lithography is using SMO-ILT, NTD or more complex pattern. Therefore in mask defect inspection, defect verification becomes more difficult because many nuisance defects are detected in aggressive mask feature. One key Technology of mask manufacture is defect verification to use aerial image simulator or other printability simulation. AIMS™ Technology is excellent correlation for the wafer and standards tool for defect verification however it is difficult for verification over hundred numbers or more. We reported capability of defect verification based on lithography simulation with a SEM system that architecture and software is excellent correlation for simple line and space.[1] In this paper, we use a SEM system for the next generation combined with a lithography simulation tool for SMO-ILT, NTD and other complex pattern lithography. Furthermore we will use three dimension (3D) lithography simulation based on Multi Vision Metrology SEM system. Finally, we will confirm the performance of the 2D and 3D lithography simulation based on SEM system for a photomask verification.

In a Photomask manufacturing process, mask defect inspection is an increasingly important topic for 193nm optical lithography. Further extension of 193nm optical lithography to the next technology nodes, staying at a maximum numerical aperture (NA) of 1.35, pushes lithography to its utmost limits. This extension from technologies like ILT and SMO requires more complex mask patterns. In mask defect inspection, defect verification becomes more difficult because many nuisance defects are detected in aggressive mask features. One of the solutions is lithography simulation like AIMS. An issue with AIMS, however, is the low throughput of measurement, analysis etc.

A new SEM technology, Advantest's Wafer MVM-SEM E3310, is becoming available that allows quantitative, image-based 3D profile metrology of nanoscale features. CD-AFM is generally employed for 3D profile information, but this technique has its own limitations for 1Xnm node production due to tip size constraints in the tightest spaces, and due to finite tip lifetime which can influence measurement stability. Using the patented multi-channel detector technology, this system can acquire information of surface concave and convex features and relative side wall angle (SWA) and height, quickly and non-destructively for nanoscale structures [1] [2]. Here we evaluate this new technology and demonstrate its applicability to contemporary advanced structures.

In next generation lithography (NGL) for the 1x nm node and beyond, the three dimensional (3D) shape measurements such as side wall angle (SWA) and height of feature on photomask become more critical for the process control. Until today, AFM (Atomic Force Microscope), X-SEM (cross-section Scanning Electron Microscope) and TEM (Transmission Electron Microscope) tools are normally used for 3D measurements, however, these techniques require time-consuming preparation and observation. And both X-SEM and TEM are destructive measurement techniques. This paper presents a technology for quick and non-destructive 3D shape analysis using multi-channel detector MVM-SEM (Multi Vision Metrology SEM), and also reports its accuracy and precision.

As design rules of lithography shrink: accuracy and precision of Critical Dimension (CD) and controllability of hard OPCed patterns are required in semiconductor production. Critical Dimension Scanning Electron Microscopes (CD SEM) are essential tools to confirm the quality of a mask such as CD control; CD uniformity and CD mean to target (MTT). Basically, Repeatability and Reproducibility (R and R) performance depends on the length of Region of Interest (ROI). Therefore, the measured CD can easily fluctuate in cases of extremely narrow regions of OPCed patterns. With that premise, it is very difficult to define MTT and uniformity of complex OPCed masks using the conventional SEM measurement approach. To overcome these difficulties, we evaluated Design Based Metrology (DBM) using Large Field Of View (LFOV) of CD-SEM. DBM can standardize measurement points and positions within LFOV based on the inflection/jog of OPCed patterns. Thus, DBM has realized several thousand multi ROI measurements with average CD. This new measurement technique can remove local CD errors and improved statistical methodology of the entire mask to enhance the representativeness of global CD uniformity. With this study we confirmed this new technique as a more reliable methodology in complex OPCed patterns compared to conventional technology. This paper summarizes the experiments of DBM with LFOV using various types of the patterns and compares them with current CD SEM methods.

A new SEM technology is becoming available that allows image-based 3D profile metrology of nanoscale features. Using patented multi-channel detector technology, this system can acquire information of surface concave and convex features, and sidewall angle (SWA) and height of profiles, quickly and non-destructively for nanoscale structures such as fin field-effect transistors (FinFETs), using electron beam technology with its well-known long probe lifetime, stability and small probe size. Here we evaluate this new technology and demonstrate its applicability to contemporary advanced structures such as FinFETs, including not only CD, but also profile, SWA, top corner rounding (TCR) and bottom corner rounding (BCR).

Bright-field photomasks are used to print small contact holes via ArF immersion multiple patterning lithography. There are some technical difficulties when small floating dots are to be measured by SEM tools because of a false imaging shadow. However, a new scan technology of Multi Vision Metrology SEM TM E3630 presents a solution for this issue. The combination of new scan technology and the other MVM-SEM® functions can provide further extended applications with more accurate measurement results.

We have studied MVM (Multi Vision Metrology) -SEM Š E3630 to measure 3D shape of defects. The four detectors (Detector A, B, C and D) are independently set up in symmetry for the primary electron beam axis. Signal processing of four direction images enables not only 2D (width) measurement but also 3D (height) measurement. At last PMJ, we have investigated the relation between the E3630¶s signal of programmed defect on MoSi-HT and defect height measured by AFM (Atomic Force Microscope). [1] It was confirmed that height of integral profile by this tool is correlated with AFM. It was tested that E3630 has capability of observing multilayer defect on EUV. We have investigated correlation with AFM of width and depth or height of multilayer defect. As the result of observing programmed defects, it was confirmed that measurement result by E3630 is well correlated with AFM. And the function of 3D view image enables to show nm order defect. Keywords: phase defects, EUV, MVM-SEM, 3D measurement, multilayer

The detection and management of mask defects which are transferred onto wafer becomes more important day by day. As the photomask patterns becomes smaller and more complicated, using Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO) with Optical Proximity Correction (OPC). To evaluate photomask quality, the current method uses aerial imaging by optical inspection tools. This technique at 1Xnm node has a resolution limit because small defects will be difficult to detect. We already reported the MEEF influence of high-end photomask using wide FOV SEM contour data of "E3630 MVM-SEM ® " and lithography simulator "TrueMask ® DS" of D2S Inc. in the prior paper [1]. In this paper we evaluate the correlation between our evaluation method and optical inspection tools as ongoing assessment. Also in order to reduce the defect classification work, we can compose the 3 Dimensional (3D) information of defects and can judge whether repairs of defects would be required. Moreover, we confirm the possibility of wafer plane CD measurement based on the combination between E3630 MVM-SEM ® and 3D lithography simulation.

To evaluate photomask quality, the current method uses spatial imaging by optical inspection tools. This technique at 1Xnm node has a resolution limit because small defects will be difficult to extract. To simulate the mask error-enhancement factor (MEEF) influence for aggressive OPC in 1Xnm node, wide FOV contour data and tone information are derived from high precision SEM images. For this purpose we have developed a new contour data extraction algorithm with sub-nanometer accuracy resulting in a wide Field of View (FOV) SEM image: (for example, more than 10um x 10um square). We evaluated MEEF influence of high-end photomask pattern using the wide FOV contour data of "E3630 MVM-SEM TM " and lithography simulator "TrueMask TM DS" of D2S, Inc. As a result, we can detect the "invisible defect" as the MEEF influence using the wide FOV contour data and lithography simulator.

As an alternative to EUV lithography, ArF immersion multiple patterning lithography has been heavily employed in semiconductor fabrication. This situation has led to increase use of bright-field photomasks with floating small patterns. Latest CDSEMs are equipped with various charge compensation features and applicable for devices with conductive and insulating material. However, there remain some difficulties when floating small patterns are to be measured. One of the specific examples is a floating dot on a via mask, dimension of which is around 200nm at the 45 nm process node, scaling down to 100nm at the 22nm process node. Since the dot has very small capacitance, it is easily charged by electron beam irradiation, and discharged in a short period. This kind of temporary voltage variation can affect the secondary electron yield, causes degradation of the SEM image contrast. We have analyzed that the "edge effect", which is the principle of SEM, has a primary role in small dot charging, and interchanging of scan line effectively suppresses the voltage variation. Based on this concept, we have developed a new scan technology for our "Multi Vision Metrology SEM" E3630, and improved the performance of image-based measurement. In this paper, the new scan technology and evaluation results are presented.

As feature sizes of semiconductor device structures have continuously decreased, needs for metrology tools with high precision and excellent linearity over actual pattern sizes have been growing. And it has become important to measure not only two-dimensional (2D) but also three-dimensional (3D) shapes of patterns at 22 nm node and beyond. To meet requirements for 3D metrology capabilities, various pattern metrology tools have been developed. Among those, we assume that CDSEM metrology is the most qualified candidate in the light of its non-destructive, high throughput measurement capabilities that are expected to be extended to the much-awaited 3D metrology technology. On the basis of this supposition, we have developed the 3D metrology system, in which side wall angles and heights of photomask patterns can be measured with high accuracy through analyzing CDSEM images generated by multi-channel detectors. In this paper, we will discuss our attempts to measure 3D shapes of defect patterns on a photomask by using Advantest's "Multi Vision Metrology SEM" E3630 (MVM-SEM™ E3630).

A new metrology method for CD-SEM has been developed to measure the side wall angle of a pattern on photomask. The height and edge width of pattern can be measured by the analysis of the signal intensity profile of each channel from multiple detectors in CD-SEM. The edge width is measured by the peak width of the signal intensity profile. But it is not possible to measure the accurate edge width of the pattern, if the edge width is smaller than the primary electron beam diameter. Using four detectors, the edge width can be measured by the peak width which appears on the subtracting signal profile of two detectors in opposition to each other. Therefore, the side wall angle can be calculated if the pattern height is known. The shadow of the side wall appears in the signal profile from the detector of the opposite side of the side wall. Furthermore, we found that there was the proportional relation between pattern height and the shadow length of the signal on one side. This paper describes a method of measuring the side wall width of a pattern and experimental results of the side wall angle measurements.

The Multiple Detector CD-SEM acquires the secondary electron from pattern surface at each detector. The 3D shape and height of mask patterns are generated by adding or subtracting signal profile of each detector. In signal profile of the differential image formed in difference between left and right detector signal, including concavo-convex information of mask patterns. Therefore, the 3D shape of mask patterns can be obtained by integrating differential signal profile. This time, we found that proportional relation between pattern height and shadow length on one side of pattern edge. In this paper, we will report experimental results of pattern height measurement. The accuracy of measurement and side wall angle dependency are studied. The proposal method is applied to OMOG masks.

Measurement of resist critical dimensions (CDs) utilizing a scanning electron microscope (SEM) based metrology system causes the resist to change due to irradiation effects of the electrons. A new and novel scanning approach has been developed in an effort to minimize the effects electron irradiation and exposure during the measurement process. This technique is especially pertinent in view of the tightening requirements for process control to achieve single digit CD uniformity on leading edge photo masks being produced today. The measurement of OPC features necessitates utilization of SEM based metrology due to resolution requirements, but the effects of high magnification imaging presents unique challenges. By controlling the scanned region of interest (ROI) it is possible to reduce exposure and irradiation effects. This paper will detail this new approach as it is utilized on the LWM9045 SEM Metrology system. The LWM9000SEM mask CD SEM was introduced earlier.