Aligned Etch Mask Formation Using Reference Mark Feedback
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Solution Overview
Problem
Forming etch masks with large dimensions is challenging due to difficulties in simultaneous monitoring and measurement of opposite boundaries, making it hard to align them accurately within manufacturing processes.
Innovation Solution
A method involving etching reference marks on a substrate to demarcate boundaries, forming etch masks with calibrated exposure settings, and iteratively measuring and adjusting the distance between the reference marks and mask boundaries to ensure alignment and correct positioning for the etch process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dimension of the etch mask is increased to accommodate large memory devices, then the capacity and scalability of the memory device is improved, but the ability to simultaneously monitor and measure opposite boundaries inline is worsened
Solution Approach 1:
The patent divides the measurement task into segments by introducing reference marks at specific locations on the substrate. Instead of attempting to measure the entire large dimension of the etch mask in one inline measurement, the process measures distances from reference marks to mask boundaries separately. This segmentation enables accurate measurement of large dimensions by breaking them into smaller, measurable segments that can be performed inline at different locations.
2Measurement precision
If specialized equipment is used to measure large etch mask dimensions, then measurement accuracy is improved, but the complexity of the manufacturing process and loss of time are worsened
Solution Approach 1:
The patent applies preliminary action by etching reference marks onto the substrate before forming the etch mask. These reference marks are prepared in advance at known locations, enabling subsequent inline measurements to be performed using existing manufacturing equipment rather than requiring specialized measurement equipment. This preliminary preparation simplifies the overall manufacturing process while maintaining measurement accuracy.
Solution Approach 2:
The patent implements feedback by measuring the distance from reference marks to etch mask boundaries and using this measurement information to adjust and align the etch mask position. The measured distances provide feedback that enables real-time correction of mask alignment, ensuring accurate positioning without requiring complex specialized measurement equipment or removing wafers from the manufacturing line.
3Area of stationary object
If the dimension of the etch mask is increased, then the area for memory array formation is improved, but the difficulty of aligning the mask boundaries accurately is worsened
Solution Approach 1:
The patent uses reference marks as intermediary elements between the substrate and the etch mask. These reference marks serve as mediator features that facilitate accurate alignment by providing known reference points for measurement. The distance measurements from reference marks to mask boundaries enable precise determination of mask positioning, maintaining alignment accuracy even as the overall mask area increases to accommodate larger memory devices.
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 the precise formation and alignment of large etch masks, allowing for accurate etching and transferring of reference marks to recesses, thereby facilitating the creation of memory arrays within specified dimensions.
Implementation Method 1
forming an etch mask on the substrate, using an exposure setting, the etch mask having a boundary
Implementation Method 2
The etch process can include etching a recess in the substrate using the etch mask
Data Source
AI summary
A method for forming an aligned mask comprises etching a reference mark on a substrate to demarcate a boundary of an etch region; forming an etch mask on the substrate, using an exposure setting, the etch mask having a boundary; and measuring a distance between the reference mark and the boundary. When the measured distance is outside a margin of a target distance, then the etch mask is removed from the substrate, the exposure setting is changed, a next etch mask is formed using the changed exposure setting, and said measuring is repeated. A set of reference marks can be etched on a top level in a set of levels to demarcate boundaries of etch regions. An etch-trim process can be performed to form steps in the set of levels, wherein the etch-trim process includes at least first and second etch-trim cycles using first and second reference marks.