Metal Gate Spacer Plasma Conversion to Prevent Short Circuits
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Solution Overview
Problem
In the fabrication of metal gate transistors, the removal of polysilicon gate material leads to issues such as boron penetration and depletion, causing short circuits between conductive materials and adjacent contact plugs, which affects device performance.
Innovation Solution
A method involving forming a metal gate with a spacer and interlayer dielectric layers, followed by a plasma treatment to transform conductive materials into dielectric portions, and subsequent cleaning to prevent short circuits, ensuring proper layer formation and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon gate material is removed during fabrication of metal gate transistor, then metal gate can be formed, but short circuits occur between conductive materials and adjacent contact plugs
Solution Approach 1:
A plasma treatment process is introduced as an intermediary step between polysilicon gate removal and metal gate formation. This plasma treatment transforms residual conductive materials into dielectric portions, preventing short circuits while enabling proper metal gate formation. The plasma process acts as a mediator that converts harmful conductive residues into beneficial dielectric material.
Solution Approach 2:
The patent applies plasma treatment to change the physical and chemical parameters of residual materials. By exposing the structure to plasma, the conductive properties of residual polysilicon or other materials are transformed into dielectric properties, effectively preventing short circuits between conductive layers and contact plugs.
2Ease of manufacture
If spacer and CESL are removed during gate material removal, then metal gate can be formed, but conductive materials form short circuit with contact plugs
Solution Approach 1:
The plasma treatment is performed as a preliminary action before metal gate deposition. This preliminary treatment ensures that any residual conductive materials from spacer or CESL removal are converted to dielectric material, preventing future short circuits while facilitating smooth metal gate formation.
Solution Approach 2:
The patent converts the harmful effect of residual conductive materials (which cause short circuits) into a beneficial dielectric layer through plasma treatment. The residual materials that would normally cause problems are transformed into useful insulating material that protects against short circuits.
3Device complexity
If conventional polysilicon gate is used, then fabrication process is simple, but boron penetration and depletion effect occur
Solution Approach 1:
The patent changes the material parameter from polysilicon to metal gate, fundamentally altering the electrical and physical properties of the gate structure. This material substitution eliminates boron penetration and depletion effects while improving device performance, despite adding some process complexity.
Solution Approach 2:
The metal gate structure may involve composite material systems including multiple metal layers, dielectric layers, and interface layers. This composite approach allows optimization of electrical properties to eliminate polysilicon-related issues while maintaining fabrication feasibility.
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 prevents short circuits by converting conductive materials into dielectric portions, ensuring the integrity of the metal gate structure and improving device performance by maintaining the correct thickness and composition of layers.
Implementation Method 1
performing a plasma treatment process to transform the spacer into a first bottom portion and a first top portion
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of forming a metal gate on a substrate, a spacer around the metal gate, and a first interlayer dielectric (ILD) layer around the spacer, performing a plasma treatment process to transform the spacer into a first bottom portion and a first top portion, performing a cleaning process to remove the first top portion, and forming a second ILD layer on the metal gate and the first ILD layer.