Mask Set for Overlay Pattern Positional Accuracy
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Solution Overview
Problem
The existing methods for manufacturing pattern multilayer bodies, such as thin film magnetic heads, face challenges in achieving high position gap measurement accuracy due to manufacturing errors between multiple masks used in the overlay pattern formation process, which affects the positional accuracy between element patterns in hard disk drives and other devices.
Innovation Solution
A method involving the use of a main mask and sub-masks to form overlay patterns, where the main mask has a pattern light-shielding part common to all layers, and sub-masks with specific light-shielding and opening parts to enhance position gap measurement accuracy orthogonal to the lamination direction, reducing errors from mask alignment and manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple masks are used for forming overlay patterns in each pattern layer, then the position gap measurement accuracy deteriorates due to manufacturing errors between masks, but using a single mask with multiple light-shielding parts increases device complexity
Solution Approach 1:
The patent combines multiple light-shielding parts that would traditionally be on separate masks into a single integrated mask structure. The mask includes a first light-shielding part for forming an overlay pattern in a first pattern layer and a second light-shielding part for forming an overlay pattern in a second pattern layer, both on the same mask. This merging eliminates manufacturing errors between multiple masks while maintaining the ability to measure position gaps between different pattern layers.
Solution Approach 2:
The single mask serves multiple functions by including different light-shielding parts that can form overlay patterns in different pattern layers simultaneously or sequentially. The mask structure is designed to be universal across multiple patterning steps, eliminating the need for separate masks for each layer while preserving measurement capability.
2Manufacturing precision
If multiple masks are used for overlay pattern formation, then manufacturing precision deteriorates due to alignment errors between masks, but using a single mask increases the area and complexity of the mask
Solution Approach 1:
The patent merges multiple alignment-critical mask structures into a single mask, eliminating cumulative alignment errors between masks. By having all light-shielding parts on one mask substrate, the manufacturing precision of overlay patterns is improved as there are no inter-mask alignment variations.
3Reliability
If multiple masks are used for forming overlay patterns, then the reliability of position gap measurement decreases due to manufacturing errors, but using a single mask with multiple light-shielding parts requires more complex mask fabrication
Solution Approach 1:
The patent combines multiple light-shielding parts into a single mask to eliminate manufacturing errors between masks, thereby improving the reliability of position gap measurements. While the mask fabrication becomes more complex, the overall manufacturing process is simplified by eliminating the need for multiple mask alignment and fabrication steps.
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 enables the formation of overlay patterns with high positional accuracy, reducing manufacturing errors and improving the accuracy of position gap measurements between pattern layers, thereby enhancing the performance of thin film magnetic heads and other pattern multilayer bodies.
Implementation Method 1
a main mask, a set of first to Nth sub masks, wherein the main mask includes a pattern light-shielding part commonly used for forming a pattern in each of the first to Nth pattern layers, and first to Nth main light-shielding parts for forming first to Nth overlay patterns, respectively
Data Source
AI summary
A method for manufacturing a pattern multilayer body that has a plurality of pattern layers, and where a pattern is formed in each pattern layer, includes a step of forming an overlay pattern within an overlay pattern formation region, and in the step of forming the overlay pattern, a photoresist film is formed, and after a photoresist film is exposed via a main mask, a resist pattern is formed by exposing a sub mask(s). The main mask has a pattern light-shielding part that is commonly used for forming a pattern in each pattern layer, and each main light-shielding part for forming each overlay pattern; and a sub mask has an opening part that is exposable to an unexposed region(s) within an overlay pattern formation region other than an unexposed region(s) on the photoresist film, which has been light-shielded by the main light-shielding part for forming a corresponding overlay pattern.