Post-Exposure Bake Chamber With Plasma-Coupled Electric Field Control
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Solution Overview
Problem
Current photolithography processes face challenges with low throughput, increased line edge roughness, and decreased resist sensitivity due to limitations in reducing feature sizes on semiconductor substrates, particularly in achieving precise and accurate pattern transfer with small wavelength lithography.
Innovation Solution
The implementation of an apparatus and method that applies an electric field guided bake process using a plasma formation system with controlled ion densities and temperatures to enhance resist layer processing, reducing line edge/width roughness and improving exposure resolution by controlling the diffusion of charged species in the photoresist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small wavelength lithography is used to reduce minimum printable size, then manufacturing precision is improved, but productivity decreases and line edge roughness increases
Solution Approach 1:
The patent applies an electric field during the post-exposure bake process to control the diffusion of charged species (protons) in the photoresist layer. By modifying the electric field parameter, the patent achieves improved line edge roughness and resist sensitivity without changing the wavelength of lithography, thereby maintaining manufacturing precision while addressing productivity issues
Solution Approach 2:
The patent creates a non-uniform electric field distribution across the photoresist layer, with different field strengths in different regions. This local variation in electric field quality allows for precise control of proton diffusion in critical areas, improving line edge roughness locally without affecting the entire substrate uniformly, thus maintaining high manufacturing precision
2Manufacturing precision
If small wavelength lithography is used to reduce minimum printable size, then manufacturing precision is improved, but line edge roughness increases
Solution Approach 1:
The patent applies an electric field during the post-exposure bake process to counteract the harmful diffusion of charged species before the development process. This preliminary anti-action prevents the formation of rough line edges by controlling proton movement in the photoresist layer, thereby eliminating line edge roughness before it can manifest in the final pattern
Solution Approach 2:
The patent uses sensors to monitor the electric field distribution and proton diffusion in real-time during the post-exposure bake process. This feedback information is used to dynamically adjust the electric field parameters, ensuring optimal control of charged species movement and maintaining smooth line edges throughout the processing
3Manufacturing precision
If small wavelength lithography is used to reduce minimum printable size, then manufacturing precision is improved, but resist sensitivity decreases
Solution Approach 1:
The patent replaces the reliance on high-energy radiation (mechanical/optical system) with an electric field-based control mechanism during post-exposure bake. By substituting the primary control method from radiation intensity to electric field strength, the patent improves resist sensitivity while maintaining the small wavelength lithography's manufacturing precision advantages
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 improves resist sensitivity and productivity by reducing the radiation dose required for achieving critical dimensions, leading to more accurate and precise pattern transfer on semiconductor substrates.
Implementation Method 1
forming a first plasma with a first ion concentration; flowing the first plasma through the diffuser to form a second plasma with a second ion concentration of about 10^4 ions/cm^3 to about 10^6 ions/cm^3
Implementation Method 2
applying a voltage differential between the diffuser and the substrate support to form an electric field across the second plasma
Implementation Method 3
controlling the diffusion of charged species in the photoresist layer
Implementation Method 4
heating a substrate with a resist layer disposed on the substrate support to a temperature of about 75° C. to about 300° C. while applying the electric field
Data Source
AI summary
A method and apparatus for performing post-exposure bake operations is described herein. The apparatus includes a plate stack and enables formation of a first high ion density plasma before the ion concentration within the first high ion density plasma is reduced using a diffuser to form a second low ion density plasma. The second low ion density plasma is an electron cloud or a dark plasma. An electric field is formed between a substrate support and the diffuser and through the second low ion density plasma during post-exposure bake of a substrate disposed on the substrate support. The second low ion density plasma electrically couples the substrate support and the diffuser during application of the electric field. The plate stack is equipped with power supplies and insulators to enable the formation or modification of a plasma within three regions of a process chamber.