Phase-shift mask

About: Phase-shift mask is a research topic. Over the lifetime, 2088 publications have been published within this topic receiving 18058 citations.

Lithographic apparatus, device manufacturing methods, devices manufactured thereby, method of manufacturing a reflector, reflector manufactured thereby and phase shift mask

Abstract: A reflector for EUV has additional multi-layers on the front surface of a base multilayer stack provided selectively to compensate for figure errors in the base multilayer stack or the substrate on which the multilayer stack is provided. A reflective mask for EUV uses two multilayer stacks, one introducing a relative phase shift and/or altered reflectivity with respect to the other one.

3D mask modeling with oblique incidence and mask corner rounding effects for the 32nm node

Abstract: The perpetual shrinking in critical dimensions in semiconductor devices is driving the need for increased resolution in optical lithography. Increasing NA to gain resolution also increases Optical Proximity Correction (OPC) model complexity. Some optical effects which have been completely neglected in OPC modeling become important. Over the past few years, off-axis illumination has been widely used to improve the imaging process. OPC models which utilize such illumination still use the thin film mask approximation (Kirchhoff approach), during optical model generation, which utilizes a normal incidence. However, simulating a three dimensional mask near-field using an off-axis illumination requires OPC models to introduce oblique incidence. In addition, the use of higher NA systems introduces high obliquity field components that can no longer be assimilated as normal incident waves. The introduction of oblique incidence requires other effects, such as corner rounding of mask features, to be considered, that are seldom taken into account in OPC modeling. In this paper, the effects of oblique incidence and corner rounding of mask features on resist contours of 2D structures (i.e. line-ends and corners) are studied. Rigorous electromagnetic simulations are performed to investigate the scattering properties of various lithographic 32nm node mask structures. Simulations are conducted using a three dimensional phase shift mask topology and an off-axis illumination at high NA. Aerial images are calculated and compared with those obtained from a classical normal incidence illumination. The benefits of using an oblique incidence to improve hot-spot prediction will be discussed.

Analysis of Nonplanar Topography Effects of Phase Shift Masks on Imaging Characteristics

Abstract: Nonplanar topography effects of phase shift masks (PSMs) on imaging characteristics are analyzed by using vector theory. Intensity distributions along the cross-sectional plane of the mask and image plane are calculated. The polarization effects of transverse electric (TE) and transverse magnetic (TM) waves are examined and the difference between the diffraction efficiency of TE waves and that of TM waves is evaluated. Imaging characteristics obtained using several types of alternate PSMs are examined, taking nonplanar topography effects into account. The lack of intensity balance between adjacent aperture images and asymmetry in the intensity with respect to the best focal plane are predicted by accurately calculating optical diffraction at the PSM. Also, 360° phase shifting by fabricating a subtractive structure in a chromeless area is examined and is found to produce a dip in the image intensity; such a dip would not be predicted by conventional scalar theory.

Method for the manufacture of phase shifting masks for EUV lithography

Abstract: A method for fabricating an EUV phase shift mask is provided that includes a substrate upon which is deposited a thin film multilayer coating that has a complex-valued reflectance. An absorber layer or a buffer layer is attached onto the thin film multilayer, and the thickness of the thin film multilayer coating is altered to introduce a direct modulation in the complex-valued reflectance to produce phase shifting features.

Method of fabricating phase shift mask

Abstract: A method of fabricating a phase shift mask (PSM) is described. A patterned photoresist layer is formed on an opaque layer over a transparent plate. A thin mask layer is formed on the sidewalls of the patterned photoresist layer. The exposed opaque layer and transparent plate thereunder are then removed while using the patterned photoresist layer and mask layer as a mask. A phase shift opening is formed in the transparent plate, and thereby a phase shift layer is formed at the place where the phase shift opening is located. The patterned photoresist layer and the opaque layer thereunder are then removed to expose the transparent plate. The opaque layer under the mask layer can precisely self-align the phase shift layer to prevent alignment deviation caused by multiple lithography processes. The precision of the phase shift mask can be increased, and mask manufacture cost can be lowered.