Conductive Superstrate Coating for UV Transparency and Charge Dissipation
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Solution Overview
Problem
Inkjet Adaptive Planarization requires a superstrate with a high flatness surface to minimize electrostatic charges between the superstrate and cured resist, which can cause increased adhesion and impurities, leading to defects in the resist.
Innovation Solution
A superstrate comprising a core body with a metal-free electrically conductive layer, such as poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate, and a capping layer made of a fluoropolymer like Cytop, both ensuring high UV transparency and electrical conductivity, to reduce electrostatic charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-conductive fused silica superstrate is used, then UV transparency is maintained, but electrostatic charges accumulate causing increased adhesion and particle attraction
Solution Approach 1:
The patent applies composite materials by combining a non-conductive fused silica core body with a conductive polymer layer coating. This composite structure allows the superstrate to simultaneously maintain UV transparency from the fused silica core while dissipating electrostatic charges through the conductive polymer layer, thus resolving the contradiction between UV transparency and electrostatic charge accumulation.
Solution Approach 2:
The patent changes the electrical conductivity parameter of the superstrate surface by applying a conductive polymer layer. This parameter change allows the surface to transition from non-conductive to conductive state, enabling electrostatic charge dissipation while the bulk material maintains its UV transparency properties.
2Object-affected harmful factors
If a conductive layer is added to reduce electrostatic charges, then electrostatic charge accumulation is minimized, but the structure becomes more complex
Solution Approach 1:
The patent uses a thin film conductive polymer layer coating on the fused silica core body. This thin film approach provides the necessary electrical conductivity to minimize electrostatic charges while adding minimal structural complexity and maintaining the overall simplicity of the superstrate design.
3Object-affected harmful factors
If a thick conductive layer is applied to ensure sufficient conductivity, then electrostatic charge dissipation is improved, but UV transparency is reduced
Solution Approach 1:
The patent employs a thin film conductive polymer layer with controlled thickness to provide sufficient electrical conductivity for electrostatic charge dissipation while minimizing the impact on UV transparency. The thin film design allows UV light to pass through effectively while still providing the necessary conductive pathway for charge dissipation.
Solution Approach 2:
The patent optimizes the thickness parameter of the conductive polymer layer to achieve the right balance between electrical conductivity and UV transparency. By carefully controlling this parameter, the superstrate maintains both effective electrostatic charge dissipation and high UV transparency for lithography applications.
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
The solution effectively minimizes electrostatic charges, enhancing the quality of the resist and increasing production throughput by maintaining high electrical conductivity and UV transparency while preventing particle attraction and adhesion issues.
Implementation Method 1
an electrically conductive layer directly overlying the first surface of the core body... the conductive layer is metal-free and comprises an electrical conductivity of at least 10−4 S/m
Implementation Method 2
the conductive layer... has a UV transparency at 365 nm of at least 80%; and the capping layer includes a fluoropolymer and has a UV transparency at 365 nm of at least 80%
Data Source
AI summary
A superstrate can comprise a core body having a first surface and a second surface, the first surface and the second surface being opposite to each other; an electrically conductive layer directly overlying the first surface of the core body; and a capping layer directly overlying the conductive layer, wherein the core body can have an electrical conductivity of not greater than 10−10 S/m; the conductive layer is metal-free and comprises an electrical conductivity of at least 10−4 S/m and a UV transparency at 365 nm of at least 80%; and the capping layer includes a fluoropolymer and has a UV transparency at 365 nm of at least 80%. The capping layer can contribute to an increase of the electrical conductivity of the underlying electrically conductive layer.