Etch Stop Detection Structure for Air Gap Endpoint Control
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Solution Overview
Problem
In semiconductor structures with air gaps, controlling the etching endpoint during the formation of upper air gaps is challenging, leading to potential damage to semiconductor devices under lower air gaps due to uncontrolled etching processes.
Innovation Solution
An etch stop detection structure and method that includes a substrate with a device region and a detection region, featuring a first dielectric layer, a first stop layer, and a second dielectric layer with a trench that exposes the first stop layer, allowing for the detection of an etch stop signal to prevent damage during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the etching process is used to form the upper air gap, then the parasitic capacitance between interconnect structures is reduced, but the etching endpoint cannot be controlled precisely causing damage to semiconductor devices under the lower air gap
Solution Approach 1:
The substrate is divided into a device region and a detection region. The detection region contains a trench structure that exposes the first stop layer, allowing separate detection of the etching endpoint without interfering with the device region. This segmentation enables independent monitoring of the etching process while maintaining device integrity.
Solution Approach 2:
A detection structure acting as an intermediary is introduced between the etching process and the semiconductor devices. The trench in the detection region provides a pathway to detect the etch stop signal from the first stop layer without the etch plasma directly contacting and damaging the devices in the device region.
2Manufacturing precision
If the air gap is disposed between interconnect structures, then the parasitic capacitance is reduced, but the control of etching endpoint becomes difficult
Solution Approach 1:
The detection function is moved to a separate spatial dimension - the detection region with the trench structure. This allows the etch stop signal to be detected laterally through the trench rather than requiring vertical endpoint detection through the air gap, making the detection process easier and more reliable.
Solution Approach 2:
The trench structure is pre-formed in the detection region before the air gap etching process. This preliminary action creates a dedicated detection pathway that exposes the first stop layer, enabling real-time monitoring of the etching endpoint during the air gap formation process.
Data Source
AI summary
An etch stop detection structure and an etch stop detection method are provided. The etch stop detection structure includes a substrate, a first dielectric layer, a first stop layer, and a second dielectric layer. The substrate includes a device region and a detection region. The first dielectric layer is located on the substrate. The first stop layer is located on the first dielectric layer. The second dielectric layer is located on the first stop layer. There is a first air gap in the first dielectric layer and the first stop layer in the device region. There is a trench in the second dielectric layer in the detection region. The trench exposes the first stop layer. The etch stop detection structure can be used to detect the etch stop signal.