Photomask Reticle with Multiple Bias Versions for Lithography Error Compensation
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing process errors and increasing yield in photomask manufacturing, particularly in sub-wavelength lithography, which leads to deviations in semiconductor feature size and shape, resulting in decreased process yield and increased costs.
Innovation Solution
A reticle with multiple versions of the same mask pattern, each with different biases, is used to compensate for process errors, allowing the customer to choose the appropriate bias for the stepper equipment, thereby optimizing the photolithography process and reducing turn-around time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single mask pattern is used in photomask manufacturing, then the manufacturing process is simple, but process errors occur during exposure leading to deviations in semiconductor feature size and shape
Solution Approach 1:
The patent divides a single mask pattern into multiple versions with different biases (e.g., +5nm, 0nm, -5nm) on the same reticle. Each version compensates for different types of process errors, allowing the semiconductor manufacturer to select the appropriate bias for their specific manufacturing conditions, thereby improving feature size and shape accuracy without significantly complicating the manufacturing process
Solution Approach 2:
The patent applies parameter changes by creating multiple mask patterns with different bias values (positive, negative, or zero). These parameter variations allow compensation for exposure process errors such as focus variations, dose variations, and lens aberrations, improving the precision of semiconductor feature dimensions while maintaining manufacturability
2Productivity
If multiple mask patterns with different biases are created on a single reticle, then process errors can be compensated and yield increases, but the reticle design and manufacturing complexity increases
Solution Approach 1:
The reticle is segmented into multiple independent mask pattern regions, each containing a different bias version of the same pattern. This segmentation allows the complex task of error compensation to be distributed across multiple simpler, pre-calculated patterns, improving yield while keeping individual pattern designs relatively simple
Solution Approach 2:
The single reticle serves multiple functions by incorporating multiple bias versions of the same mask pattern. This multi-functionality allows one reticle to compensate for various types of process errors and accommodate different manufacturing conditions, thereby increasing productivity without requiring multiple separate reticles
3Productivity
If traditional single-pattern photomasks are used, then manufacturing costs are lower, but inspection and correction steps are required increasing costs and turn-around time
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-creating multiple bias versions of mask patterns during reticle manufacturing. This advance preparation eliminates the need for post-manufacturing inspection and correction steps, as the appropriate bias is already built into the reticle. While initial reticle manufacturing may have higher complexity, it eliminates subsequent costly inspection and correction operations, reducing overall turn-around time
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
This approach increases process yield and reduces turn-around time by enabling precise compensation for process errors, improving pattern fidelity and reducing costs associated with inspection and correction steps.
Implementation Method 1
The top layer is a photosensitive resist material 8. As the E beam or laser beam is scanned across the blank photomask, the exposure system directs the E beam or laser beam at addressable locations on the photomask... In the case of a positive photoresist, the areas that are exposed to the E beam or laser beam become soluble, while the unexposed portions remain insoluble
Implementation Method 2
The desired pattern of opaque material to be created on the photomask may be defined by an electronic data file loaded into an exposure system which typically scans an electron beam (E beam) or laser beam in a raster fashion across the blank photomask
Data Source
AI summary
A reticle includes at least two duplicate mask patterns each having a different bias. A reticle according to at least one embodiment of the invention includes a first mask pattern, a second mask pattern and a third mask pattern, each of the first mask pattern, second mask pattern and third mask pattern being duplicates of one another and having a different bias.