Anti-reflective Layer for Semiconductor Photoresist Undercut
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Solution Overview
Problem
In semiconductor device manufacturing, the reduction in device size leads to undercuts in photoresist patterns due to diffuse reflection, causing ions to be implanted into undesired portions of the substrate, which deteriorates device characteristics.
Innovation Solution
A method involving the formation of anti-reflective layers with a thin thickness on the substrate, allowing precise ion implantation into active regions without altering the ion implantation conditions, and preventing damage to the active regions by not etching the anti-reflective layers during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If photoresist layer is patterned to define active regions, then device size is reduced, but undercut occurs in photoresist pattern due to diffuse reflection
Solution Approach 1:
An anti-reflective layer is introduced as an intermediary between the photoresist layer and the substrate. This layer prevents diffuse reflection of light during photoresist patterning, eliminating undercut formation while allowing continued scaling of device dimensions.
Solution Approach 2:
The anti-reflective layer is formed on the substrate before the photoresist layer is deposited and patterned. This preliminary action prevents the undercut problem from occurring during the subsequent photoresist patterning process, enabling precise definition of active regions even at reduced device sizes.
2Device complexity
If photoresist pattern is formed without anti-reflective layer, then manufacturing process is simpler, but ions are implanted into undesired portions of substrate
Solution Approach 1:
The anti-reflective layer serves as a protective intermediary that prevents ion implantation into undesired portions of the substrate. By blocking ions during the implantation process, it ensures that impurity regions are formed only in the intended active regions, maintaining device reliability.
Solution Approach 2:
The anti-reflective layer, which adds a step to the manufacturing process, actually simplifies the overall process by eliminating the need for additional protective measures or rework. It converts the potential harm of ion implantation into undesired regions into a benefit by providing automatic protection during implantation.
3Reliability
If anti-reflective layer is formed with thin thickness, then ion implantation conditions are not altered and active regions are not damaged, but layer formation precision must be increased
Solution Approach 1:
The thickness of the anti-reflective layer is optimized to a specific range that allows it to function as an effective ion implantation mask without significantly altering ion implantation conditions. This parameter optimization enables the layer to protect active regions while maintaining compatible implantation characteristics.
Solution Approach 2:
The anti-reflective layer is formed with a thickness that replicates the protective function of a thicker layer without the detrimental effects. By finding the optimal thin thickness, the layer provides sufficient protection while maintaining transparency to ion implantation conditions and avoiding damage to underlying active regions.
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 ensures accurate ion implantation into desired regions, reducing undercuts and maintaining the integrity of the active regions, thereby improving the characteristics of the semiconductor devices.
Implementation Method 1
an undercut may occur in the photoresist pattern due to diffuse reflection in patterning the photoresist layer
Implementation Method 2
Impurities are implanted into the second active region to form a first impurity region
Data Source
AI summary
In a method of manufacturing a semiconductor device, an isolation layer pattern is formed on a substrate to define a field region covered by the isolation layer pattern and first and second active regions that is not covered by the isolation layer pattern and protrudes from the isolation layer pattern. A first anti-reflective layer is formed on the isolation layer pattern. A first photoresist layer is formed on the first and second active regions of the substrate and the first anti-reflective layer. The first photoresist layer is partially etched to form a first photoresist pattern covering the first active region. Impurities are implanted into the second active region to form a first impurity region.