3D Memory Overlay Mark Formation for Reliable Alignment Measurement
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Solution Overview
Problem
Accurate measurement of misalignment between layers in the manufacturing of 3D semiconductor memory devices is difficult due to the complexity of the process, limiting the integration density and reliability of overlay marks.
Innovation Solution
A method for forming an overlay mark involving a substrate with a lower overlay, a pattern layer, and an upper overlay with different light transmittance areas, allowing for precise measurement of misalignment through controlled light emission and trench formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional overlay marks are used in 3D semiconductor memory device manufacturing, then the number of process steps is increased, but the measurement precision of misalignment data from lower overlay marks deteriorates
Solution Approach 1:
The overlay mark is divided into multiple regions with different light transmittance characteristics. The first region has higher light transmittance while the second region has lower light transmittance, allowing selective light transmission to preserve measurement precision despite increased process steps
Solution Approach 2:
Different regions of the overlay mark are assigned different material properties (light transmittance). This local differentiation enables the overlay mark to simultaneously serve multiple functions: maintaining alignment reference capability while accommodating additional processing steps
2Device complexity
If conventional overlay marks are used with increased process steps, then manufacturing complexity increases, but the reliability of overlay measurement deteriorates
Solution Approach 1:
The overlay mark structure is pre-configured with regions of different light transmittance before the measurement process. This preliminary structural preparation ensures that even with increased manufacturing complexity, the measurement reliability is maintained by having the light transmission characteristics already in place
Solution Approach 2:
The material layer with different light transmittance regions acts as an intermediary between the upper overlay and the detection system. This intermediary structure protects the measurement reliability by controlling light transmission while accommodating the complexity of additional manufacturing 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
Enhances the reliability of overlay measurement by adjusting light transmittance and forming trenches, ensuring accurate inspection of layer alignment and maintaining scribe lane integrity.
Implementation Method 1
forming a material layer on the upper overlay, wherein the material layer includes a third area corresponding to the first area and a fourth area corresponding to the second area; emitting light to the upper overlay through the material layer
Data Source
AI summary
Disclosed are a method for forming an overlay mark with improved reliability and an overlay measurement method using the overlay mark. The method for forming the overlay mark includes forming a lower overlay in a substrate; forming a pattern layer on the substrate; forming an upper overlay on the pattern layer, wherein the upper overlay includes a first area and a second area; forming a material layer on the upper overlay, wherein the material layer includes a third area corresponding to the first area and a fourth area corresponding to the second area; emitting light to the upper overlay through the material layer; and removing a portion of the upper overlay using the light.