Semiconductor Overlay Measurement for Thick Capping Layer Alignment
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Solution Overview
Problem
The challenge in semiconductor DRAM structure manufacturing lies in accurately aligning a capacitor with an active region due to the large thickness of the capping layer, making it difficult to measure alignment between the two.
Innovation Solution
A method involving a test substrate with exposed conductive structures, where first and second images are captured using an electron microscope, and marks are identified to determine position offsets between the substrate and capping layer, allowing for alignment adjustments in the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thick capping layer is used to cover the active region, then the capacitor can be properly formed and protected, but alignment measurement between the active region and capacitor becomes difficult
Solution Approach 1:
The patent introduces an intermediary measurement method that uses the side wall profile of the capping layer as a reference marker. Instead of attempting to measure through the thick capping layer directly, the system captures images of the side wall profile and uses image processing to determine the position offset between the active region and capacitor, thereby enabling precise alignment measurement despite the thick capping layer.
2Reliability
If the capping layer thickness is increased for proper capacitor formation, then device functionality is improved, but the difficulty of detecting and measuring alignment increases
Solution Approach 1:
The patent uses the side wall profile of the capping layer as an intermediary marker for alignment detection. By capturing images of this profile and processing them to extract position information, the system overcomes the difficulty of detecting alignment through thick layers while maintaining reliable capacitor formation.
Solution Approach 2:
The patent creates a visual copy of the side wall profile through imaging and uses this copied information for measurement purposes. The image processing system extracts positional data from the captured profile image, enabling non-contact, non-invasive alignment measurement that doesn't require penetrating or removing the thick capping layer.
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 method enables precise alignment of capacitor openings with conductive structures, improving the electrical properties of DRAM arrays by correcting position offsets and ensuring accurate stacking of layers.
Implementation Method 1
capturing a first image of the top surface of the test substrate... capturing a second image of a top surface of the test capping layer... The first and second images are captured by an electronic microscope
Data Source
AI summary
A method of semiconductor overlay measuring includes following operations. Provide a test substrate. Conductive structures are located in the test substrate and exposed from a top surface of the test substrate. Positioning the test substrate to a standard position and capturing a first image of the top surface of the test substrate. Mark first marks corresponding to the exposed conductive structures on the first image. Form a test capping layer with capacitor openings on the top surface of the test substrate. Move the test substrate to the standard position and capturing a second image of a top surface of the test capping layer. Identify the capacitor openings on the second image with second marks. Compare the first marks with the second marks to determine a position offset between the test substrate and the test capping layer.