Spatial Light Modulation for Critical Dimension Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photolithographic exposure techniques often result in undesirable critical dimensions (CDs) and variations, leading to device defects and compromised performance due to lack of precise control over feature dimensions during semiconductor fabrication.
Innovation Solution
A spatially-controlled projection of electromagnetic radiation using a pixel-based system, such as a micro-mirror array, is applied to selectively activate photoresist acid generators before or after lithographic exposure, allowing for precise adjustment of critical dimensions by modulating the photoresist acid content, thereby achieving uniformity and correcting feature dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithographic exposure techniques are used, then the patterning process is simple and fast, but the critical dimension uniformity and feature dimension control are poor
Solution Approach 1:
The exposure system is segmented into multiple independent light sources with different wavelengths (first light source at 193nm, second light source at 405nm). Each light source independently contributes to photoacid generation in the photoresist, allowing separate control of exposure parameters to achieve precise critical dimension uniformity without requiring a complete system redesign
Solution Approach 2:
The system changes the wavelength parameter of light used for exposure by combining 193nm deep ultraviolet light with 405nm visible light. This parameter change enables differential photoacid generation rates and solubility modifications in the photoresist, providing an additional degree of freedom to control critical dimensions and improve uniformity while maintaining process compatibility
2Manufacturing precision
If single wavelength light exposure is used, then the exposure process is fast and simple, but the control over photoresist solubility and critical dimensions is insufficient
Solution Approach 1:
The first light source (193nm) performs preliminary exposure to generate initial photoacid in the photoresist, creating a baseline pattern. The second light source (405nm) then performs a supplementary exposure that selectively modifies photoacid concentration in specific regions, enabling fine-tuned control of critical dimensions and solubility without requiring complete re-exposure
Solution Approach 2:
The photoresist is formulated as a composite material containing photoacid generator components that respond differently to 193nm and 405nm wavelengths. This composite formulation enables differential photoacid generation and solubility changes when exposed to combined wavelengths, providing enhanced control over feature dimensions while maintaining a single-exposure process flow
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 significantly improves critical dimension uniformity across substrates, enabling finer control and reducing semiconductor fabrication costs by allowing for precise tuning of feature dimensions and reducing defects.
Implementation Method 1
A pattern of electromagnetic radiation is projected onto the patterning film... causing photoacid to form in the patterning layer according to the pattern of electromagnetic radiation
Implementation Method 2
modulating the photoresist acid content, thereby achieving uniformity and correcting feature dimensions
Data Source
AI summary
Techniques herein include systems and methods that provide a spatially-controlled projection of electromagnetic radiation, such as light, onto a substrate as a mechanism of controlling or modulating critical dimensions of various features and structures being micro-fabricated on a substrate. Combining such spatial light projection with photolithographic exposure can achieve significant improvements in critical dimension uniformity across a surface of a substrate. In general, methods herein include patterning processes that identify or receive a critical dimension signature that spatially characterizes critical dimension values that correspond to the substrate. A pattern of electromagnetic radiation is projected onto a patterning film coated on substrate using a digital pixel-based projection system. A conventional photolithographic exposure process is executed subsequent to, or prior to, the pixel-based projection. The patterning film can then be developed to yield a relief pattern having critical dimensions shaped by both exposure processes.