Browse Prior Art Database

Single Phase Shifting Mask Using Bright Field and Double Exposure

IP.com Disclosure Number: IPCOM000007570D
Publication Date: 2002-Apr-05
Document File: 5 page(s) / 132K

Publishing Venue

The IP.com Prior Art Database

Abstract

A single phase shifting mask (PSM) can be used to form shapes on a wafer. This PSM uses chrome to define the shapes. The chrome is patterned on a light-transmitting section of the PSM having a first phase. Shifters of a second phase can be positioned relative to the shapes to provide sub-wavelength features.

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SINGLE PHASE SHIFTING MASK USING BRIGHT FIELD AND DOUBLE
EXPOSURE

Brief Summary of the Invention
A single phase shifting mask (PSM) can be used to form
shapes on a wafer. This PSM uses chrome to define the
shapes. The chrome is patterned on a light-transmitting
section of the PSM having a first phase. Shifters of a
second phase can be positioned relative to the shapes to
provide sub-wavelength features.

Figure P1 illustrates one embodiment of a PSM that
eliminates the need for a corresponding binary mask. This
PSM can be fabricated using a light-transmitting material
having a first phase (in this embodiment, 0°). Chrome,
shown in red, can be used to define the pattern on this
bright field mask. Phase shifters (hereinafter, shifters)
of a second phase can be formed on the PSM to provide sub-
wavelength features for the shapes in the pattern. For
example, one shifter is shown in Figure P1 (in this
embodiment, having a phase of 180) to provide a sub-
wavelength width for the line defined by the chrome.

Figure P2 illustrates three simulations of wafer printing
using the PSM of Figure P1.

The first (left) simulation is the resulting image of the
PSM using typical PSM exposure settings. Typical exposure
settings for a PSM include a low partial coherence factor
(sigma) and on-axis illumination. In this particular
example, sigma=0.3. Other exposure settings used include a
defocus f=0 and a numerical aperture (NA)=0.6.

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The blue portion of the printed image indicates a low
intensity, the red portion of the printed image indicates a
high intensity, and the yellow portion of the printed image
indicates an intermediate intensity. The high intensity
correlates to a high exposure, whereas the low intensity
correlates to a low exposure. As evidenced by the
substantially red area surrounding the blue shape in the
printed image (particularly in the area corresponding to
the direct transition from 0...