Self-Aligned Semiconductor Contact via Etching Stop Layer
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Solution Overview
Problem
The challenge in forming contacts on semiconductor devices is misalignment between contacts and source/drain regions, which can be mitigated but results in increased device size, compromising integration.
Innovation Solution
A method involving the formation of an etching stop layer with different selectivity than the first dielectric layer, used as a self-aligned mask to create contact holes, ensuring accurate alignment and reducing the risk of misalignment during contact formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the width of source/drain regions is increased to mitigate misalignment, then alignment tolerance is improved, but device size increases
Solution Approach 1:
An etching stop layer is introduced as an intermediary between the first dielectric layer and the second dielectric layer. This stop layer serves as a self-aligned mask during contact hole formation, providing precise alignment reference without requiring wider source/drain regions. The stop layer is selectively removed after contact formation to complete the contact holes, thus achieving accurate alignment while maintaining compact device dimensions.
Solution Approach 2:
The etching stop layer is formed in advance before the second dielectric layer is deposited. This preliminary formation of the stop layer establishes the alignment reference early in the fabrication process, enabling self-aligned contact hole formation subsequent to the deposition of the second dielectric layer, thereby ensuring precise contact alignment without increasing device footprint.
2Area of stationary object
If conventional contact formation is used, then device size is reduced, but misalignment between contacts and source/drain regions occurs
Solution Approach 1:
The etching stop layer acts as a mediator that provides a selective etching interface between the first and second dielectric layers. During contact hole formation, this stop layer remains intact while the second dielectric layer is etched, ensuring that contact holes are precisely aligned with the source/drain regions. After contact formation, the stop layer is selectively removed to complete the contact holes, achieving accurate alignment without increasing device size.
Solution Approach 2:
The invention utilizes etching selectivity as a key parameter to differentiate the etching behavior of the etching stop layer from the first and second dielectric layers. By controlling the etching parameters to selectively remove the second dielectric layer while preserving the stop layer during contact hole formation, precise alignment is achieved. Subsequent selective removal of the stop layer completes the contact holes, resolving the alignment issue without compromising device compactness.
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 allows for the fabrication of self-aligned contacts with a larger processing window, enabling smaller device dimensions and higher integration levels while preventing short circuits.
Implementation Method 1
The etching stop layer and the first dielectric layer have different etching selectivity
Data Source
AI summary
A method of forming a contact on a semiconductor device is provided. First, a substrate is provided. A plurality of gate structures defined by a plurality of word lines in a first direction, and a plurality of diffusion regions covered by a first dielectric layer in a second direction are provided over the substrate. The gate structures located underneath the word lines and isolated by the diffusion regions. Then, an etching stop layer is formed. The etching stop layer and the first dielectric layer have different etching selectivity. A second dielectric layer is formed over the substrate. Furthermore, a plurality of contact holes to the diffusion regions between the word lines are formed by using the etching stop layer as a self-aligned mask.