The present highly competitive state of the PV industry is putting the pressure on both crystalline and thin film
manufactures to deploy advanced architectures as a means to differentiate their products and protect market share. c-Si back side contact passivation, selective emitter opening and selective emitter doping are three efficiency improving
processes that can utilize lasers that the industry is rapidly moving to adopt. Emitter Wrap Through (EWT) is another
advanced architecture which will likely see adoption in the coming years for which lasers are a critical component of the process. Improved laser TCO patterning is of interest not only for CdTe solar cells but also for display and other micro electronics applications. Laser processing results for these various solar PV materials are presented both in terms of performance, materials science, and morphology as they relate to temporal characteristics of the laser pulse.
Using scatterometry based on Spectroscopic Ellipsometry, a complete study of Gate lithography level measurement on standard products has been conducted. Experiments were done on typical ST batches for 120, 90, and 65 nm nodes. KLA-Tencor SpectraCD SE system is used to collect and analyze line critical dimensions and profiles. A systematic correlation with Scanning Electron Microscope (SEM) is done, completed by a cross section analysis. The study also takes into account lithography defect anlysis using a specific targets with intentionally generated process failures. Our objective is to determine the sensitivity window of such measurment technique to process defect and marginal process conditions. We show that KLA-Tencor SpectraCD allows a full reconstruction of the line profile - as well as the film stack underneath it - with values that are in agreement with production control. Cpm values obtained on products demonstrate that SE based scatterometry fulfils all requirements to be integrated in a production envrionemnt and provides suitable metrology for advanced lithography process monitoring.
In the production of sub 140nm electronic devices, CD metrology is becoming more critical due to the increased demands placed on process control. CD metrology using CD-SEM is approaching its limits especially with respect to precision, resolution and depth of field. Potentially, scatterometry can measure structures down to 50nm with the appropriate precision. Additionally, as scatterometry is a model based technique it allows a full reconstruction of the line profile and the film stack. In this work we use SE based scatterometry in the control of a 110nm DRAM WSix Gate process at the Litho and the Mask Open step. We demonstrate the use of a single trapezoid as a basic shape model in FEM and field mapping applications as well as in a high volume production test. The scatterometry results are compared to CD-SEM data. We show that for the GC Litho application, n&k variations in some of the stack materials do not affect the scatterometry CD measurement significantly.
A systematic study has been conducted to evaluate accuracy and precision of spectral scatterometry used for two-dimensional (2D) characterization of trenches formed in fluorinated silicon glass (FSG). Experiments were done on short-flow dual-damascene Cu interconnect material. Trench critical dimensions (CD) obtained using KLA-Tencor's spectral scatterometer were correlated with data collected using CD atomic force microscope (AFM), CD scanning electron microscope (SEM) and transmission electron microscope (TEM). 3 major trench characteristics were analyzed: trench width, trench depth and sidewall angle. Spectral scatterometry demonstrated an excellent correlation (above 0.96) with CD AFM and SEM in tested trench width range of (80-240) nm and trench depth range of (410-450) nm. Spectral scatterometry showed acceptable correlation of 0.55 and minimal offset of 0.05 degrees with AFM in tested sidewall angle range of (87.5-89) degrees. Spectral scatterometry has demonstrated better than 1.0 nm and 0.2 degrees dynamic precision (3s) for both width and height and sidewall angle, respectively. We conclude that KLA-Tencor's SpectraCD system is capable of accurate and precise 2D characterization of FSG trenches. We recommend scatterometry as a high throughput and non-destructive metrology for trench linewidth and depth monitoring in low-K dielectric interconnect manufacturing.
KEYWORDS: Single crystal X-ray diffraction, Critical dimension metrology, Semiconducting wafers, Scanning electron microscopy, Process control, Spectroscopy, Spectroscopes, Metrology, Precision measurement, Control systems
Smaller device dimensions and tighter process control windows have created a need for CD metrology tools having higher levels of precision and accuracy. Furthermore, the need to detect and measure changes in feature profiles is becoming critical to in-line process control and stepper evaluation for sub-0.18micrometers technology. Spectroscopic CD (SCDTM) is an optical metrology technique that can address these needs. This work describes the use of a spectroscopic CD metrology tool to measure and characterize the focus and exposure windows for the process. The results include comparison to the established in-line CD-SEM, as well as a cross-section SEM. Repeatability and long-term stability data form a gate level nominal process are also presented.
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