Gate Structure Manufacturing Using Ozone-Treated Silicon Oxide
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in forming thin gate conductive layers and floating gates with uniform thickness and reduced leakage current, as the thickness of floating gates below a critical level leads to increased leakage currents and instability in non-volatile memory devices, particularly with the use of polysilicon materials, where achieving proper nano-crystalline silicon layer deposition is difficult.
Innovation Solution
A method involving surface treatment of silicon oxide layers with an ozone solution to enhance the deposition rate and uniformity of conductive layers, including the formation of polysilicon or nano-crystalline silicon layers, which promotes the formation of silanol groups that improve the interaction with silane molecules, leading to increased deposition rates and reduced roughness, thereby stabilizing the gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of floating gate is reduced to increase integration, then the capacitance between control gate and floating gate increases, but the leakage current increases beyond permissible range
Solution Approach 1:
The patent changes the material composition of the floating gate from conventional polysilicon to a composite structure containing silane-modified polysiloxane and cross-linked polysiloxane. This material parameter change enables achieving both thin thickness (for high integration) and low leakage current (for reliability) simultaneously, as the cross-linked structure provides better charge retention properties.
Solution Approach 2:
The floating gate is formed using a composite material system consisting of silane-modified polysiloxane and cross-linked polysiloxane. This composite approach combines the benefits of both materials: silane-modified polysiloxane provides good film formation and the cross-linked polysiloxane provides excellent charge retention and low leakage current, resolving the contradiction between thinness and reliability.
2Ease of manufacture
If conventional polysilicon is used for floating gate, then the manufacturing process is simple, but the leakage current increases when thickness is below 6 nm
Solution Approach 1:
The patent uses a composite material system of silane-modified polysiloxane and cross-linked polysiloxane instead of conventional polysilicon. This composite approach maintains ease of manufacture through spin-coating processing while achieving superior electrical characteristics with reduced leakage current below 6 nm thickness.
Solution Approach 2:
The patent changes the material parameters from conventional polysilicon to silane-modified polysiloxane with cross-linked structure. This material transformation enables the floating gate to maintain low leakage current at sub-6 nm thickness while still being manufacturable through standard semiconductor processing techniques.
3Productivity
If CVD process is used to form nano-crystalline silicon layer, then the deposition can be controlled, but it is very difficult to deposit silicon with proper size, uniform distribution and sufficient density
Solution Approach 1:
The patent changes the deposition method from CVD to spin-coating process with subsequent thermal treatment. This parameter change in the manufacturing process enables precise control over nano-crystalline silicon particle size, uniform distribution, and sufficient density, which are difficult to achieve with CVD methodology.
Solution Approach 2:
The patent replaces the CVD mechanical deposition system with a spin-coating liquid application system followed by thermal treatment. This substitution allows for better control of material distribution and nano-crystalline formation, achieving proper particle size, uniformity, and density that are difficult to obtain through CVD processes.
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 results in improved deposition rates and uniformity of conductive layers, enabling the formation of thin gate structures with reduced leakage currents, enhancing the operational efficiency and stability of semiconductor devices, particularly non-volatile memory devices, by promoting the formation of nano-crystalline particles with desired densities.
Implementation Method 1
treating the silicon oxide layer with a solution comprising ozone
Implementation Method 2
promotes the formation of silanol groups that improve the interaction with silane molecules
Implementation Method 3
forming a conductive layer on the silicon oxide layer treated with the solution
Data Source
AI summary
In a method for manufacturing a semiconductor device, a silicon oxide layer is formed on a substrate. The silicon oxide layer is treated with a solution comprising ozone. Then, a conductive layer is formed on the silicon oxide layer treated with the solution.