Plug Structure Formation via Anisotropic Etching for High Aspect Ratio Openings
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Solution Overview
Problem
In semiconductor fabrication, the existing cleaning processes for high aspect ratio openings, such as argon cleaning, often result in over-rounded top corners of plug holes, leading to barrier bridge problems and short circuits due to the inability to effectively remove unwanted oxides without deforming the dielectric layer, which affects device performance.
Innovation Solution
A method involving a punching through process using an anisotropic etching technique, like RF sputtering, to remove unwanted oxides and glue layers at the bottom of openings, allowing for the formation of a conductive structure with a barrier layer that maintains the original shape of the opening, thereby preventing short circuits and improving step coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If argon cleaning process is enhanced or process time is extended to remove unwanted oxides, then oxide removal effectiveness is improved, but the top corner of the plug hole becomes over-rounded
Solution Approach 1:
A glue layer is deposited on the sidewall and bottom of the opening before the cleaning process. This preliminary action protects the opening structure during subsequent cleaning, preventing over-rounding while allowing effective oxide removal at the bottom of the opening.
Solution Approach 2:
The glue layer acts as an intermediary protective layer between the cleaning process and the dielectric layer. It selectively protects the sidewalls and top corners during cleaning while permitting oxide removal at the opening bottom, thus mediating between cleaning effectiveness and shape preservation.
2Reliability
If F-base cleaning process is used to remove oxides, then oxide removal is achieved, but the critical dimension of the contact plug is enlarged
Solution Approach 1:
The glue layer serves as a protective intermediary that prevents F-base cleaning solution from excessively attacking the dielectric layer edges. This mediation allows oxide removal while maintaining the critical dimension precision of the contact plug.
Solution Approach 2:
The glue layer provides localized protection specifically at the sidewalls and bottom of the opening, allowing different parts of the structure to experience different cleaning intensities. The bottom receives full cleaning action while the protected sidewalls maintain their dimensional precision.
3Manufacturing precision
If the opening has high aspect ratio, then the plug structure is formed, but the cleaning process cannot effectively remove bottom oxides without deforming the dielectric layer
Solution Approach 1:
The glue layer acts as a sacrificial intermediary that enables effective cleaning at the bottom of high aspect ratio openings. It protects the dielectric layer from deformation while allowing complete oxide removal at the opening bottom where electrical connection is critical.
Solution Approach 2:
The glue layer is deposited in advance to create a protective framework before cleaning. This preliminary protective action enables subsequent aggressive cleaning at the opening bottom without compromising the structural integrity of the dielectric layer.
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 method effectively removes unwanted oxides without deforming the opening, preventing short circuits and enhancing the contact profile and step coverage, leading to improved device performance by maintaining the integrity of the plug structure and reducing contact resistance.
Implementation Method 1
A method involving a punching through process using an anisotropic etching technique, like RF sputtering, to remove unwanted oxides and glue layers at the bottom of openings
Implementation Method 2
A method involving a punching through process using an anisotropic etching technique, like RF sputtering, to remove unwanted oxides and glue layers at the bottom of openings
Data Source
AI summary
A method for forming a plug structure includes the following steps. A substrate is provided. The substrate includes a MOS device with a source/drain region, a dielectric layer disposed on the MOS device, an opening defined in the dielectric layer, and a first glue layer disposed on a sidewall and a bottom of the opening. A portion of the first glue layer disposed at the bottom of the opening is punched through to expose the source/drain region. A barrier layer is formed over the substrate after the first glue layer is punched through. The opening is filled with a conductive structure, wherein the barrier layer disposed at the bottom of the opening is remained when the conductive structure is filled into the opening.