Multilayer defects cause severe reflectivity deformation and the degradation of through-focus imaging quality in Extreme ultraviolet (EUV) lithography. EUV mask repair techniques have primarily focused on the mask modification method to deal with the imaging contrast loss originating from multilayer defects. A multilayer defect compensation method based on three dimensional absorber correction considering through-focus imaging optimization and imaging contrast loss recovery is proposed in this paper. The proposed method compensates for the degradation of the imaging quality caused by multilayer defects with a certain defocus range by shifting the edge of the mask pattern and controlling the absorber thickness of the edge. The interactions between various absorber thicknesses and multilayer defect compensation are explored. Simulations verify that the through-focus imaging quality of the defective masks with bump defects could be obviously improved by the proposed method.
Due to the multilayer structure of the extreme ultraviolet(EUV) mask, it is easy to produce defects during the fabrication of the EUV mask, resulting in the deformation of the multilayer and thus changing the optical characteristics of the mask. Detection of defects in the EUV mask is one of the challenges of EUV lithography. In this paper, simulation analysis of defect inspection by Fourier ptychography(FP) is performed. The defective mask blanks' aerial images at different illumination angles are simulated. The amplitude and phase of the aerial images are reconstructed using FP. The effects of light source bandwidth, the number of the multilayer, angular deviation, and imaging noise of the reconstructed aerial image are analyzed. The simulation results show that the loss of intensity and phase shift of the aerial images are different with illuminations of different wavelengths. The reconstructed amplitudes of the aerial images are affected by the wavelengths within the EUV bandwidth. The flatness of the top profile of the phase defect is the key factor affecting the aerial images of the mask. Appropriately increasing the number of the multilayer can reduce the loss of intensity of the aerial images. Excessive angular deviation will affect the reconstructed amplitude and phase of the aerial images. Gaussian noise with a specific Signal-Noise Ratio(SNR) reduces the accuracy of the reconstructed amplitude and phase of the aerial images.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.