Oxygen-Rich BPSG Layers Preventing Lateral Etching
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Solution Overview
Problem
The formation of inter-layer dielectric (ILD) layers in integrated circuits, particularly those using boronphosphosilicate glass (BPSG), faces challenges such as void formation and lateral etching due to the accumulation of boron and phosphorous, which worsens at smaller technology nodes, leading to electrical property shifts and device failure.
Innovation Solution
A method involving ionized oxygen treatment, followed by forming an initial silicon oxide layer with a high oxygen-to-TEOS ratio, a buffer layer with a lower oxygen-to-TEOS ratio, and a BPSG layer, where the buffer layer acts as an adhesion layer and penetration stop, improving gap filling and reducing lateral etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BPSG is used as inter-layer dielectric, then dielectric function is achieved, but void formation occurs due to non-uniform deposition
Solution Approach 1:
The patent segments the dielectric structure into multiple layers: a bottom dielectric layer, an intermediate layer, and a top BPSG layer. This segmentation allows each layer to have optimized properties - the bottom layer provides dielectric function while the intermediate layer with lower oxygen content prevents void formation by enabling more uniform deposition of the top BPSG layer.
Solution Approach 2:
The patent applies local quality by creating layers with different oxygen contents at different positions in the structure. The intermediate layer has lower oxygen content than the top BPSG layer, which locally modifies the deposition characteristics to improve gap filling uniformity in critical regions while maintaining dielectric function in other areas.
2Reliability
If BPSG is used as inter-layer dielectric, then dielectric function is achieved, but lateral etching occurs during contact opening formation
Solution Approach 1:
The patent introduces an intermediate layer between the bottom dielectric layer and the top BPSG layer. This intermediate layer acts as a mediator that protects the underlying structures from lateral etching during contact opening formation, while still allowing the BPSG layer to perform its dielectric function. The intermediate layer with lower oxygen content provides this protective barrier.
Solution Approach 2:
The patent applies preliminary action by forming the intermediate layer with lower oxygen content before depositing the top BPSG layer. This preliminary layer preparation modifies the structure in advance to prevent lateral etching from propagating into the underlying devices during subsequent processing steps.
3Reliability
If BPSG is used as inter-layer dielectric, then dielectric function is achieved, but boron and phosphorous penetrate into devices causing electrical property shift
Solution Approach 1:
The intermediate layer with lower oxygen content serves as a barrier layer that prevents boron and phosphorous from penetrating into the underlying devices. This intermediary layer blocks the diffusion path of these dopants while allowing the overlying BPSG layer to maintain its dielectric function.
Solution Approach 2:
The patent forms the intermediate protective layer in advance before any dopant diffusion can occur. This preliminary barrier prevents boron and phosphorous penetration into devices throughout subsequent processing steps, protecting electrical properties while maintaining dielectric function.
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 enhances the gap filling ability of dielectric layers, reduces lateral etching, and prevents boron and phosphorous penetration into devices, thereby improving the reliability and performance of integrated circuits.
Implementation Method 1
performing an ionized oxygen treatment to the surface
Implementation Method 2
forming an initial layer comprising silicon oxide using first process gases comprising a first oxygen-containing gas and tetraethoxysilane (TEOS)
Data Source
AI summary
An integrated circuit structure and a method of forming the same are provided. The method includes providing a surface; performing an ionized oxygen treatment to the surface; forming an initial layer comprising silicon oxide using first process gases comprising a first oxygen-containing gas and tetraethoxysilane (TEOS); and forming a silicate glass over the initial layer. The method may further include forming a buffer layer using second process gases comprising a second oxygen-containing gas and TEOS, wherein the first and the second process gases have different oxygen-to-TEOS ratio.