SLM-Based Maskless Lithography Reticle Emulation
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Solution Overview
Problem
Optical Maskless Lithography (OML) faces challenges in achieving high throughput and process compatibility with existing semiconductor manufacturing technologies, particularly due to the high cost and sensitivity of reticles, and the need for a system that can emulate patterns produced with traditional reticles, including phase-shift patterns and OPC features, to enhance user confidence and speed up the acceptance of new systems.
Innovation Solution
The implementation of a Spatial Light Modulator (SLM)-based system that combines multiple micro-mechanical SLMs with the ASML TWINSCAN platform, using a 193 nm wavelength and a maximum Numerical Aperture (NA) of 0.93, to generate mask patterns in real-time, replacing the reticle stage with an image generating subsystem capable of delivering high data volumes and maintaining process transparency, while utilizing a diffractive mode micromirror device and calibration techniques to achieve sub-nanometer precision and high throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional reticles are used for mask-based lithography, then manufacturing precision and process compatibility are maintained, but cost increases and throughput decreases
Solution Approach 1:
The patent creates a virtual reticle by digitally copying and emulating traditional reticle patterns using an SLM device. The SLM reproduces reticle-like patterns including phase-shift patterns and OPC features through software-controlled light modulation, eliminating the need for physical reticle fabrication while maintaining pattern quality
Solution Approach 2:
The patent replaces the mechanical reticle system with an optical SLM-based system. Instead of physically manufacturing and handling reticles, the system uses a spatial light modulator to dynamically generate patterns through software control, substituting mechanical reticle operations with optical modulation
2Manufacturing precision
If traditional reticles are used for mask-based lithography, then pattern quality is maintained, but device complexity and cost increase
Solution Approach 1:
The system copies reticle functionality into software, creating a virtual reticle that emulates traditional reticle patterns. This digital copying approach maintains pattern quality while eliminating the complexity of physical reticle manufacturing, storage, and handling infrastructure
Solution Approach 2:
The SLM device serves multiple functions: it acts as a reticle, a pattern generator, and a programmable mask all in one component. This multi-functionality consolidates what would otherwise require separate reticle fabrication facilities, pattern writing equipment, and mask handling systems
3Productivity
If SLM-based maskless lithography is implemented, then throughput and cost-effectiveness improve, but process compatibility and user confidence may deteriorate
Solution Approach 1:
The system copies the optical and imaging characteristics of traditional reticles into the SLM platform. By replicating reticle-like behavior including phase-shift patterns and OPC features, the system maintains compatibility with existing lithography processes and resist formulations
Solution Approach 2:
The SLM acts as an intermediary between digital pattern data and the lithographic process. It translates software-defined patterns into optical patterns that mimic traditional reticle output, serving as a bridge that maintains process compatibility while enabling maskless operation
4Manufacturing precision
If high-precision pattern generation is achieved through SLM calibration, then manufacturing precision improves, but device complexity and calibration requirements increase
Solution Approach 1:
The system replaces mechanical precision mechanisms with software-based calibration and control. Instead of relying on mechanically precise reticle positioning and alignment, the SLM uses digital calibration algorithms and software-controlled adjustments to achieve sub-nanometer pattern precision
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 enables cost-effective, high-precision printing with improved throughput, maintaining compatibility with existing fab technologies, and facilitating the transition from low-volume maskless to high-volume mask-based production by producing images with similar quality to traditional reticles, with negligible grid snapping or aliasing effects and significant reduction in CD uniformity errors.
Implementation Method 1
The SLM is in diffractive mode, as opposed to being in specular mode
Implementation Method 2
providing a first complex reflection coefficient for a first mirror and a second complex reflection coefficient for a second adjacent mirror of the SLM
Data Source
AI summary
The present invention relates to Optical Maskless Lithography (OML). In particular, it relates to providing OML with a recognizable relationship to mask and phase-shift mask techniques.