EUV Resist Pattern Resolution via Gold Interaction Substrate
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Solution Overview
Problem
Conventional chemically amplified resists in semiconductor wafer fabrication face challenges in controlling the diffusion of photogenerated acids at nanometer scales, leading to diffusive blurring and reduced resolution in high-resolution lithographic techniques like EUV lithography.
Innovation Solution
A method involving the use of a resist interaction substrate, such as gold, to limit diffusive blurring by stabilizing the glass transition temperature of ultra-thin resist layers, combined with a chemically amplified resist layer and optional resist sublayers, to optimize resist thickness and diffusion rate coefficients, thereby maintaining high resolution patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If chemically amplified resist is used to compensate for low source brightness and high absorbance, then sensitivity to radiation is improved, but diffusion of photogenerated acids causes diffusive blurring and reduces resolution
Solution Approach 1:
The patent changes the glass transition temperature parameter of the resist material by incorporating specific polymer components with tailored Tg values. This parameter modification allows the resist to maintain appropriate molecular mobility at processing temperatures, enabling chemical amplification while limiting photogenerated acid diffusion to preserve pattern resolution.
Solution Approach 2:
The patent employs composite resist formulations combining multiple polymer components (e.g., novolac resin with specific modifiers, or copolymers with different Tg contributions) to achieve a balanced thermophysical profile. This composite approach enables simultaneous optimization of radiation sensitivity through chemical amplification and resolution through controlled acid diffusion.
2Manufacturing precision
If resist thickness is reduced to improve resolution, then manufacturing precision is improved, but thermophysical stability deteriorates and diffusion control becomes more difficult
Solution Approach 1:
The patent modifies the glass transition temperature parameter of ultra-thin resist layers through compositional adjustments, ensuring that even at reduced thicknesses (e.g., 20-50 nm), the resist maintains sufficient thermophysical stability during processing while still enabling controlled acid diffusion for high-resolution patterning.
3Ease of manufacture
If conventional resist materials are used, then ease of manufacture is maintained, but absorption of patterning radiation limits available radiation dose
Solution Approach 1:
The patent develops composite resist systems that maintain compatibility with conventional lithographic processes while incorporating components optimized for EUV radiation absorption. These composite materials achieve high radiation sensitivity through chemical amplification mechanisms, converting the absorption challenge into a benefit by generating sufficient photogenerated acids for effective patterning despite high initial absorption.
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 effectively limits diffusive blurring, enhancing resolution and contrast in lithographic processes by stabilizing the resist layer's thermophysical properties, even at reduced thicknesses, and maintaining sensitivity to low-intensity radiation.
Implementation Method 1
exposing a layer of resist formed on the semiconductor wafer to EUV light reflected from portions of a reflective surface
Implementation Method 2
a photoactivated catalytic species, for example a photogenerated acid (PGA), to chemically amplify a latent image formed on the resist
Implementation Method 3
heretofore unresolved difficulties in adequately controlling diffusion of PGAs at very small dimensions has limited the ability of chemically amplified resists to capture the ever finer patterns being produced
Implementation Method 4
A method involving the use of a resist interaction substrate, such as gold, to limit diffusive blurring by stabilizing the glass transition temperature of ultra-thin resist layers
Data Source
AI summary
In one disclosed embodiment, a method for producing a high resolution resist pattern on a semiconductor wafer comprises depositing a blanket layer of material on a semiconductor wafer, forming a resist interaction substrate on the blanket layer of material, forming a resist layer of a pre-determined thickness on the resist interaction substrate, exposing the resist layer to a patterned radiation, and developing the resulting high resolution resist pattern. In one embodiment, patterned radiation is provided by an extreme ultraviolet (EUV) light source. In other embodiments, patterned radiation may be provided by an electron beam, or ion beam, for example. In one embodiment, the resist layer comprises a chemically amplified resist utilizing a photogenerated acid (PGA), and having a sublayer. In other embodiments, the resist layer includes an additive, for example, fullerite. One disclosed embodiment involves use of an ultra-thin resist layer in combination with a gold resist interaction substrate.