This paper presents an innovative use of machine learning (ML) to improve etch modeling by integrating monotonic machine learning methods with ML-based contour metrology. Unlike traditional methods that rely on single gauge-based data, our approach leverages comprehensive contour data extracted from SEM images to predict etching biases. It handles large datasets efficiently and adapts dynamically to new data. A primary element of our strategy involves constructing a retargeting layer with etch bias, derived from features at multiple sites or points of interest (POIs) on a reference layer which is generated with a fuzzy clustering model. These features and their corresponding etch biases serve as training data for our semi-supervised model which will be used for prediction on large scale designs.
The new high numerical aperture (0.55NA) Extreme Ultraviolet Lithography (EUVL) machine has been developed by ASML, which is using an anamorphic projection system with the demagnification of 4× in x-direction and 8× in y-direction. Due to the unchanged 6-inch mask, 0.55NA EUVL reduces the exposure field size to half-field (26×16.5mm2). Therefore, the in-die stitching between two exposures might be needed for the applications requiring larger than half-field size. To enable High-NA EUV in die stitching, a complete mask data correction flow is needed. In this paper, we will investigate the in-die stitching effects and solution by using Ta-based dark field mask. We will show the impact of pattern types and decomposition rules on the stitching strategy, in addition to methods for correcting these stitching effects in optical proximity correction from an EDA perspective.
In this paper, we introduce a method that employs a deep learning model, built with GPU, to extract contours from a variety of SEM images. The model is trained with images and their corresponding ground truth. Various models are explored, and their predictive results are juxtaposed with the known ground truth. In comparison with CPU, utilizing GPU can augment the speed approximately 20 times.
We present a contour metrology-based process matching flow with machine learning-based site selection for best coverage, contour comparisons, and scoring to quantify process differences. This method can significantly improve the efficiency of process technology transfers between fabs. The key technology includes: 1) high-performance ML clustering on a full chip product with hundreds of millions of anchoring points, 2) process-matching oriented custom feature engineering that drives quantitative understanding of each SEM image, and 3) stable and reliable contour extraction of large amounts of CD-SEM images.
This conference presentation was prepared for the Advanced Etch Technology and Process Integration for Nanopatterning XII conference at SPIE Advanced Lithography + Patterning 2023.
With the adoption of extreme ultraviolet (EUV) lithography for high volume production in the advanced wafer manufacturing fab, defects resulting from stochastic effects could be one of major yield killers and draw increasing interest from the industry. In this paper, we will present a flow, including stochastic edge placement error (SEPE) model calibration, pattern recognition and hot spot ranking from defect probability, to detect potential hot spot in the chip design. The prediction result shows a good match with the wafer inspection. HMI eP5 massive metrology and contour analysis were used to extract wafer statistical edge placement distribution data.
KEYWORDS: Inspection, Scanning electron microscopy, Copper, Semiconducting wafers, Defect inspection, Optical inspection, Back end of line, Chemical mechanical planarization, Electrons, Wafer inspection
We report an optical inspection guided e-beam inspection method for inline monitoring and/or process change validation. We illustrate its advantage through the case of detection of buried voids/unlanding vias, which are identified as yield-limiting defects to cause electrical connectivity failures. We inspected a back end of line (BEOL) wafer after the copper electro plating and chemical mechanical planarization (CMP) process with bright field inspection (BFI) and employed EBI to inspect full wafer with guidance of BFI klarf file. The dark voltage contrast defects were detected and confirmed as buried voids by transmission electron microscopy (TEM).
KEYWORDS: Inspection, Optical proximity correction, Image classification, Semiconductors, Virtual colonoscopy, Diffusion, Metals, Data analysis, Failure analysis, Defect inspection, Ions, Electron beams, Defect detection, Back end of line
A novel classification methodology is constructed for Electron Beam (E-Beam) die-to-database (D2DB) inspection results on contact and via layers. It is a design guided defects classification flow that helps to pin-point true defects from a large amount of false alarm defects. Die-to-database E-beam inspection has remarkable features that can help find systematic defects such as Damaged Via and Missing Via; which will be reported as DVC (Dark Voltage Contrast) defects. However, the D2DB result usually reports millions of defects that lie on both ‘active via’ and ‘floating via’, the former being defects-of-interest (DOI), and the latter being of little significance. The indiscriminant mixture of DOI (on active vias) and nuisance (on floating vias) is a challenge in the use of D2DB for finding systematic via defects. We overcome this challenge by overlaying the E-beam defect location onto the design layout file (GDS or OASIS) and tracing the path of the via to determine whether or not it connects to the active or diffusion layer. Our proposed flow uses Net Tracing Classification (NTC) feature in Anchor Hotspot Solution (AHS) to classify all the reported DVC defects into different groups, according to the electrical connectivity of the contact. This classification involves multiple interconnected process layers. All the reported DVC defects will be classified into three groups: (1) Real DVC defects, in which the net traces down to active layer; (2) False DVC type 1, in which the net traces down to gate (which is always dark); (3) False DVC type 2, in which the net traces down to floating metal (which is always dark as well). This enhanced defect classification is greatly helpful in separating real DVC contact/via defects from false alarms. It has a secondary benefit of reducing the total number of defects, which is helpful for subsequent in-depth data analysis. In addition, the verified real DVC locations can be used to generate care areas for E-Beam die-to-die (D2D) inspection, which can effectively improve throughput and reduce the turn-around-time (TAT). In this paper, we will discuss a use case at the Vx layer.
We report an in situ formed tunable liquid microlense array and its applications for enhancing dynamic lab-on-a-chip performance. The de-ionized water microlenses are intrinsically formed via liquid-air interfaces of liquid droplets at T-shaped junctions of octadecyltrichlorosilane(OTS) treated polymerized isobornyl acrylate(poly(IBA)) microchannels., and can be separately tuned in focal lengths by pneumatic manipulation. Via the tunable microlenses, excitation light is dynamically focused onto the fluorescent fluidic sample, thus the fluorescence emission signal for detection is amplified. We have further shown the potential for surface reaction study at microfluidic interfaces by the microlense array.
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