Semiconductor Alignment Mark via Through-Hole IR Reflection
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Solution Overview
Problem
In semiconductor manufacturing, the existing methods face challenges in achieving accurate positional alignment during the lithography process due to low signal strength from infrared light used to visualize alignment marks through the semiconductor substrate, especially when a stacked structure is present above the alignment mark, leading to unclear contrast and difficulty in determining the position of the alignment mark.
Innovation Solution
The method involves forming an alignment mark on the semiconductor substrate, removing the stacked structure above it, and using infrared light to enhance the contrast of the reflected light beams, allowing for accurate positional alignment by improving the signal strength from the alignment mark, thereby facilitating precise exposure and pattern formation during the lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stacked structure is present above the alignment mark, then the semiconductor device achieves high functionality and high integration, but the signal strength from infrared light is reduced and contrast becomes unclear
Solution Approach 1:
The alignment mark is extracted from beneath the stacked structure by forming it in a through-hole that penetrates the stacked structure from the first surface to the second surface. This allows the alignment mark to be accessible from both sides, enabling infrared light to reflect off it clearly without being blocked by the stacked structure, thus resolving the contradiction between maintaining high integration and achieving measurement precision.
Solution Approach 2:
The alignment mark is positioned in a through-hole that extends through the stacked structure in the vertical dimension, allowing infrared light to access it from the second surface (opposite side) rather than being blocked from the first surface side. This dimensional approach enables the alignment mark to serve both the high integration requirement and the measurement precision requirement.
2Ease of manufacture
If infrared light is used to visualize the alignment mark through the semiconductor substrate, then the lithography process can be performed, but the signal strength is low and contrast is poor
Solution Approach 1:
The through-hole acts as an intermediary structure that provides a clear optical path for infrared light to reach the alignment mark and reflect back. By creating this dedicated pathway through the stacked structure, the infrared light can effectively visualize the alignment mark with high contrast, maintaining both manufacturing ease and measurement precision.
Solution Approach 2:
The alignment mark is formed with a specific material composition (different from the stacked structure materials) that creates a distinct reflectivity contrast for infrared light. This material differentiation ensures that the alignment mark appears with high contrast under infrared illumination, enabling precise visualization during lithography while maintaining process capability.
3Ease of operation
If the alignment mark is formed on the front surface side, then it is easily accessible, but it interferes with the stacked structure formation
Solution Approach 1:
The semiconductor substrate is segmented into different functional regions: the stacked structure occupies the front surface area for high integration, while the through-hole containing the alignment mark is formed in a separate region (such as a scribe line or dedicated alignment region). This segmentation allows both the stacked structure and alignment mark to coexist without interference, maintaining both device complexity and ease of operation.
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 improves the reliability and yield of semiconductor devices by ensuring accurate positional alignment and TSV formation, as the enhanced contrast between reflected light beams clearly defines the alignment mark's position, enabling precise lithography and improved manufacturing outcomes.
Implementation Method 1
Infrared light (IR) is used in order to visualize an alignment mark through the semiconductor substrate from the rear surface side of the semiconductor substrate
Implementation Method 2
performing positional alignment for exposure of a resist pattern based on the location of the alignment mark using infrared light reflected from the alignment mark
Data Source
AI summary
According to one embodiment, there is provided a method of manufacturing a semiconductor device which includes forming an alignment mark in a planned cutting line region of a first surface of a semiconductor substrate, forming a stacked structure above the first surface of the semiconductor substrate, removing the portion of the stacked structure present above the alignment mark, aligning the substrate in the lithography process, by causing infrared light to pass through the semiconductor substrate from a second surface thereof which is on a side opposite to the first surface thereof and performing positional alignment for exposure of a resist pattern based on the location of the alignment mark using infrared light reflected from the alignment mark, and exposing the resist, opening a pattern in the exposed resist, and further processing the semiconductor substrate using the resist pattern.