Akitoshi Kawai

Novel CD inspection technology leveraging a form birefringence in a Fourier space

A new technology was developed to detect Critical Dimension (CD) variations in a Fourier space. The detection principle is a form birefringence of the wafer. Utilizing this principle, CD and Pattern Edge Roughness (PER) variations are detected as a polarization fluctuation and converted into light intensity. We have achieved high resolution and high sensitivity by combining a form birefringence with a novel optical system. This system detects the light intensity in a Fourier space with a high NA objective, enabling the detection of various lights with different incident angles and polarization states at a time. We have confirmed through simulations that this system has high sensitivity toward CD variations. Furthermore, in partnership with Toshiba Corporation, and through the evaluation of wafers fabricated at Toshiba, we conclude that the light intensity detected by the new system strongly correlates with CD values, and that the new system is capable of detecting CD variations in sufficient sensitivity.

New Measurement Technology for CD and Pattern Profile Variation using Optical Fourier Space

As well as measuring CD, monitoring pattern profile is becoming important for semiconductor metrology. Illuminating the wafer and detecting the reflective light, reflective light intensity in the Fourier space includes the information of CD and pattern profile variation by form birefringence effect. CD change and profile variation could be detected separately for the actual wafer. Mathematical simulation is presented the background of our unique approach. The detail results of CD and pattern profile monitor is shown in this paper.

New Inspection Technology for Hole Pattern by Fourier Space on hp 4x-nm Generation

We tried to detect the CD variation of the 4x generation hole pattern using the diffraction light on Fourier space with the polarized light and the modified illumination. The new technology named DD (Dual Diffraction) method has been developed based on the optical simulation and the experimental approaches. We introduce the case of detection for the diameter variation on a multi-layered hole pattern with new method.

Hole inspection technology using Fourier imaging method

There are two kinds of critical dimension (CD) management tools; CD-SEM and Optical CD (OCD). OCD is preferable to other existing measurement tools, because of its higher throughput and lower photoresist damage. We have developed an Automated Pattern profile Management (APM) systems based on the OCD concept. For the monitoring thin line, APM detects light intensity from an optical system consisting of a polarizer and an analyzer set in a cross- Nicol configuration as a polarization fluctuation. This paper reports our development of monitoring technology for hole. In the case of hole management, APM detects light intensity from diffraction intensity fluctuation. First of all, the best conditions for hole management were designed from simulations. The best conditions were off-axis aperture and S polarizer. In our evaluation of wafers without underlayer, we obtained a good correlation with CD-SEM value. From the simulation, we consider the APM system to be very effective for shrinking hole process management of the next generation from the simulation.