Exposure Mask Supplementary Pattern Array for Sub-0.15 μm Resolution
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Solution Overview
Problem
Current projection exposure technologies face challenges in forming fine contact hole patterns below 0.15 μm due to limitations in numerical aperture and wavelength, and the optimal arrangement of supplementary patterns on masks for high-resolution exposure is not well understood, leading to increased developing costs and inconsistent results.
Innovation Solution
A mask manufacturing and exposure method that selects from three supplementary pattern arrangements based on the intersection angle between the desired pattern and supplementary pattern holes, specifically a normal array, offset array, or diagonal array, to achieve high-resolution exposure of patterns with hole diameters of 0.15 μm or less, by optimizing the pitch and position of supplementary patterns relative to the desired pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If normal exposure methods are used with binary masks, then manufacturing process is simple, but resolution cannot achieve below 0.15 μm
Solution Approach 1:
The mask pattern is segmented into two distinct components: the desired pattern (contact holes to be formed) and the supplementary pattern (auxiliary structures with smaller dimensions). This segmentation allows each pattern type to be optimized independently - the desired pattern maintains standard dimensions while the supplementary pattern uses reduced dimensions to manipulate diffraction effects, thereby achieving sub-0.15 μm resolution without overly complicating the overall mask structure.
Solution Approach 2:
Different regions of the mask are assigned different qualities and functions. The desired pattern regions use standard hole sizes and spacing appropriate for the target device geometry, while the supplementary pattern regions use smaller hole sizes and different spacing specifically optimized for controlling light diffraction. This local differentiation enables high-resolution imaging without requiring the entire mask structure to be redesigned.
2Manufacturing precision
If supplementary patterns are added to achieve high resolution, then imaging characteristics improve, but mask design complexity increases
Solution Approach 1:
The invention systematically varies key parameters of the supplementary pattern - including hole size, spacing, and arrangement geometry - to optimize imaging characteristics for different desired pattern configurations. By establishing parameter relationships between the desired pattern and supplementary pattern, the design process becomes more structured and less trial-and-error oriented, reducing overall design complexity while maintaining high imaging quality.
Solution Approach 2:
The supplementary pattern is designed and positioned in advance during mask fabrication, with its parameters predetermined based on the desired pattern geometry. This preliminary design approach allows the supplementary pattern to pre-compensate for diffraction effects before exposure, eliminating the need for complex real-time adjustments during the exposure process and simplifying the overall workflow.
3Manufacturing precision
If optimal supplementary pattern array is determined through trial exposure, then exposure quality improves, but developing time and costs increase
Solution Approach 1:
The supplementary pattern uses smaller, less critical structural elements that can be designed and fabricated with standard techniques. By making these auxiliary structures smaller and less prominent than the main desired pattern, the mask remains relatively simple to manufacture and inspect, avoiding the need for expensive, time-consuming trial exposures to optimize every detail.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-resolution exposure of fine contact hole patterns with reduced developing time and costs by determining the optimal array of supplementary patterns based on pattern pitch, improving imaging characteristics and depth of focus, and allowing for the formation of patterns with hole diameters less than 0.15 μm.
Implementation Method 1
The halftone mask is a mask for attenuating light intensity on a portion corresponding to a light-shielding portion of a binary mask, and also keeping a phase difference of 180° as to a light-transmitting portion
Implementation Method 2
The phase shift mask is a mask designed to have mutually constant phase differences in the event of incident light toward the mask passing through a light-transmitting portion. This can be achieved by maintaining the mutual phase difference of adjacent light at 180° and mutually counteracting the amplitude of the center portions thereof
Implementation Method 3
projection exposure apparatuses for projecting a pattern drawn on a mask (rectile) onto a wafer using a projection optical system and transferring the pattern
Implementation Method 4
The resolution R of a projection exposure apparatus is obtained by the following Rayleigh's expression, using wavelength λ of light source and numerical aperture NA of a projection optical system
Data Source
AI summary
A mask manufacturing method suitable for an exposure method wherein a mask on which a desired pattern and a supplementary pattern with formations smaller than those of the desired pattern are arrayed is illuminated, and the light which passed through the mask onto a member to be exposed is projected via a projection optical system, said method comprising a selecting step for selecting one of the following three supplementary patterns, a first supplementary pattern wherein said supplementary pattern is disposed at a position where a line extending in the vertical direction as to the pitch direction from a certain desired pattern hole of said desired pattern, and a line connecting the supplementary pattern hole closest to said certain desired pattern hole in the vertical direction with said certain desired pattern hole, intersect at an angle of 0°, a second supplementary pattern wherein said angle is 0° or more but less than 45°, and a third supplementary pattern wherein said supplementary pattern supplementary pattern is disposed at a position where said is disposed at a position where said angle is 45°.