Contact Hole Alignment Monitoring Using Electron Microscopy
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Solution Overview
Problem
Current optical methods for detecting misalignment between contact holes and polycrystalline silicon gates in semiconductor manufacturing are limited by resolution size, leading to performance failures and yield issues when device dimensions are 65 nanometers or less.
Innovation Solution
A method involving the placement of equidistant contact holes on poly-silicon gates and active areas, using an electron microscope to detect and calculate deviation values, where the length of the poly-silicon gate is determined by the diameter of the contact hole, pitch, and width, allowing for precise alignment monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical method is used to detect misalignment between contact hole and poly-silicon gate, then detection can be performed, but resolution is insufficient for 65 nanometer or less device dimensions
Solution Approach 1:
The patent changes the detection parameter from optical wavelength to electron beam wavelength. By using electron microscopy instead of optical microscopy, the detection system achieves sub-10 nanometer resolution capability, which is sufficient for 65 nanometer and smaller device dimensions. This parameter change in the detection method enables precise measurement of contact hole alignment with poly-silicon gates at advanced technology nodes.
2Area of moving object
If device size is scaled down to 65 nanometers or less, then integration density is improved, but alignment accuracy requirement becomes more stringent
Solution Approach 1:
The patent introduces a new dimensional aspect to alignment monitoring by creating an extended poly-silicon gate structure that protrudes beyond the active area. This additional spatial dimension provides a reference framework for detecting contact hole alignment. By observing whether contact holes are formed on the protruding gate portion or the active area, the system can accurately measure alignment deviations even at 65 nanometer scale.
3Reliability
If misalignment between contact hole and poly-silicon gate occurs, then device performance is improved, but actual device performance fails
Solution Approach 1:
The patent performs preliminary alignment monitoring before final device fabrication is completed. By detecting contact hole alignment with the extended poly-silicon gate structure at an intermediate process stage, the system can identify misalignment issues early. This preliminary detection allows for process correction before subsequent fabrication steps, preventing performance failures that would result from undetected misalignment.
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 improves process quality control and product yield by providing quantized alignment profiles, enabling precise alignment even at smaller device sizes.
Implementation Method 1
an electron microscope is used to detect the contact hole in said step S3
Data Source
AI summary
The present invention is related to the semiconductor manufacturing field, especially a method for monitoring alignment between contact holes and polycrystalline silicon gate by setting a plurality of equidistant contact holes with same sharp on poly-silicon and residual active area, and then obtain the process alignment profile of the quantized values in the plane in order to have a better control of process quality, thereby have a better control of the quality of the process.