Semiconductor Etch Stop Region for Planar Substrate Thinning
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Solution Overview
Problem
As semiconductor devices undergo miniaturization, challenges arise in maintaining planarity and reducing the number of layers required for interconnect structures, leading to issues with dishing and pattern loading during substrate thinning processes, which affect the quality and yield of subsequent lithographic steps.
Innovation Solution
The formation of an etch stop region in the substrate by implanting impurities, followed by an anneal to reduce implantation defects, slows down the substrate thinning process and improves planarity, allowing for reduced layer requirements in interconnect structures and enhanced device uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If substrate thinning process is performed to reduce the number of layers, then layer count is reduced, but dishing and pattern loading effects occur degrading planarity
Solution Approach 1:
The patent applies local quality by creating an etch stop region with different impurity concentration than the surrounding substrate. This localized modification causes the substrate to thin at different rates in different regions, maintaining planarity at the surface while allowing overall thickness reduction. The etch stop region acts as a buffer that prevents excessive thinning in specific areas, thereby eliminating dishing and pattern loading effects.
2Quantity of substance
If minimum feature size is reduced to improve integration density, then integration density is improved, but additional manufacturing problems arise
Solution Approach 1:
The patent changes the physical and chemical parameters of the substrate by implanting impurities at specific concentrations and depths to form an etch stop region. This parameter modification allows the substrate to be thinned more uniformly, providing better control over feature dimensions and reducing variability in minimum feature size, thereby supporting higher integration density without sacrificing manufacturing precision.
3Device complexity
If substrate is thinned to reduce layer requirements, then layer count is reduced, but dishing effects degrade surface quality
Solution Approach 1:
The patent applies preliminary action by forming the etch stop region with modified impurity concentration before the substrate thinning process. This pre-modification ensures that during subsequent thinning operations, the substrate removes material at a controlled rate, preventing dishing effects from occurring in the first place. The etch stop region is prepared in advance to guide the thinning process and maintain surface flatness throughout.
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 planarity of the thinned surface, reduces dishing and pattern loading effects, and enhances the quality and yield of semiconductor devices by maintaining improved speed performance and energy efficiency.
Implementation Method 1
an etch stop region may be formed by implanting a region of impurities in the substrate
Implementation Method 2
followed by an anneal to reduce implantation defects
Data Source
AI summary
A method includes implanting impurities in a semiconductor substrate to form an etch stop region within the semiconductor substrate; forming a transistor structure on a front side of the semiconductor substrate; forming a front-side interconnect structure over the transistor structure; performing a thinning process on a back side of the semiconductor substrate to reduce a thickness of the semiconductor substrate, wherein the thinning process is slowed by the etch stop region; and forming a back-side interconnect structure over the back side of the semiconductor substrate.