Phase Shift Mask Blank Lamination for ArF Haze Resistance
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Solution Overview
Problem
Existing phase shift masks face issues with haze formation due to the accumulation of chromium compounds and transition metal carbides on the surface, which affect optical characteristics and reduce productivity in semiconductor manufacturing, especially with the use of ArF excimer laser exposure.
Innovation Solution
A phase shift mask blank with a laminated light shielding film structure comprising layers of chromium, oxygen, nitrogen, and carbon, and a phase shift film made of silicon without carbon, designed to prevent the formation of chromium compounds and transition metal carbides, ensuring the mask's optical characteristics remain stable even after exposure to high-energy light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a phase shift mask uses a conventional light shielding film containing chromium and carbon, then the mask can be manufactured with standard materials, but haze forms on the surface due to accumulation of chromium compounds and transition metal carbides during ArF excimer laser exposure
Solution Approach 1:
The light shielding film is divided into multiple layers with different compositions. The first layer contains chromium and carbon for easy manufacturing, while the second layer contains chromium and oxygen to prevent haze formation. This segmentation allows each layer to perform its specific function independently.
Solution Approach 2:
The invention uses composite material structure for the light shielding film, combining different chromium-based compounds in separate layers. The first layer uses chromium carbide or chromium oxycarbide nitride, while the second layer uses chromium oxide, creating a composite structure that provides both manufacturability and haze resistance.
2Productivity
If the mask is exposed to high-energy ArF excimer laser light for extended periods, then productivity increases through continuous manufacturing, but haze accumulates on the surface reducing optical characteristics
Solution Approach 1:
The second layer containing chromium oxide is prepared in advance during mask manufacturing. This layer acts as a preventive barrier that stops haze formation before it can occur during extended exposure to ArF excimer laser light, thereby extending mask lifespan without reducing productivity.
3Ease of manufacture
If chromium and carbon are both present in the light shielding film, then the film can be formed with conventional materials, but transition metal carbides form on the surface causing haze
Solution Approach 1:
The harmful combination of chromium and carbon is separated into different layers. The first layer contains chromium and carbon for manufacturability, while the second layer extracts the carbon component and replaces it with oxygen, forming chromium oxide that prevents haze formation by eliminating the source of harmful carbide compounds.
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 prevents haze formation and maintains optical properties, enhancing productivity by reducing defects and extending the photomask's lifespan in semiconductor manufacturing processes.
Implementation Method 1
a phase of a transmitted being having passed through an opening of a mask pattern (phase shift film pattern) is adjusted to be inverted by about 180 degrees with respect to a phase of a transmitted being having passed through a portion adjacent to the opening, whereby the light intensity is weakened at a boundary portion between the transmitted beams when the transmitted beams interfere with each other
Data Source
AI summary
A phase shift mask blank includes a phase shift film and a light shielding film formed in contact with the phase shift film and formed of a material containing chromium, wherein the phase shift film is formed of a material containing silicon and free of carbon, the light shielding film is formed of a material containing chromium, oxygen, nitrogen, and carbon, the light shielding film has a laminated structure including four layers: a first layer, a second layer, a third layer, and a fourth layer, the first layer being a layer farthest from the transparent substrate, and the fourth layer being a layer in contact with the phase shift film, and the second layer is a layer containing carbon, and the fourth layer contacting the phase shift film is a layer free of carbon.