EUV Lithography Stack With Electron Booster Layer for Lower Dose
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Solution Overview
Problem
EUV lithography in semiconductor manufacturing faces challenges with high exposure doses, leading to reduced throughput and increased costs due to the need for multiple patterning techniques and expensive EUV scanners, and the high photon energy of EUV radiation limits effective exposure of photoresist.
Innovation Solution
A method involving a two-layer lithography stack with a base layer that enhances photoresist exposure using energetic electrons from below, reducing the EUV radiation dose required by selecting a specific composition and thickness of the base layer to boost electron flux, thereby improving throughput and lowering manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EUV lithography is used for high resolution patterning, then manufacturing precision is improved, but productivity deteriorates due to high exposure dose requirements
Solution Approach 1:
The patent introduces an electron booster layer as an intermediary component between the substrate and photoresist. This layer absorbs EUV radiation and generates energetic electrons that expose the photoresist more efficiently, acting as a mediator that converts photon energy into electron flux to improve patterning efficiency and reduce required exposure dose.
Solution Approach 2:
The patent changes the physical and chemical parameters of the lithography stack by introducing a specific electron booster layer with controlled thickness (1-10 nm) and material composition (high atomic number elements). This parameter change enables more efficient energy conversion from EUV photons to electrons, thereby improving productivity without sacrificing patterning precision.
2Manufacturing precision
If EUV radiation is used for patterning, then manufacturing precision is improved, but use of energy increases due to high exposure dose requirements
Solution Approach 1:
The patent replaces the direct photon-to-photoresist exposure mechanism with an electron-mediated exposure mechanism. Instead of relying solely on EUV photons to expose the photoresist, the electron booster layer converts photon energy into energetic electron flux, which then exposes the photoresist more efficiently, reducing the overall energy input required.
Solution Approach 2:
The patent changes the energy conversion parameters by introducing materials with high atomic numbers in the electron booster layer. These materials have higher photoelectric absorption coefficients, enabling more efficient conversion of EUV photon energy into electron kinetic energy, thereby reducing the total exposure dose needed to achieve the same patterning effect.
3Manufacturing precision
If multiple patterning techniques are used to achieve high resolution, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the electron generation function from the photoresist layer itself and places it in a dedicated electron booster layer. This separation allows the photoresist to focus solely on pattern formation while the booster layer handles energy conversion, simplifying the overall process by enabling single-step high-resolution patterning without requiring multiple patterning cycles.
Solution Approach 2:
The electron booster layer serves multiple functions simultaneously: it acts as a radiation absorption layer, an electron generation source, and an interface layer between substrate and photoresist. This multi-functionality consolidates what would otherwise require multiple separate process steps, reducing device complexity while maintaining high manufacturing 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
The method reduces EUV radiation dose by 10% to 50%, enhancing photoresist exposure and increasing throughput, while maintaining pattern quality, thus addressing the high cost and throughput limitations of EUV lithography.
Implementation Method 1
exposing a second portion of the photoresist layer with a pattern of electron flux from the second side, the electron flux being directed into the photoresist layer from the base layer in response to the EUV radiation
Implementation Method 2
a portion of the EUV radiation is absorbed below the photoresist layer to generate the electron flux
Data Source
AI summary
A method for fabricating a semiconductor device is described that includes forming a base layer over a top layer of a substrate, the base layer includes a silicon based dielectric having a thickness less than or equal to 5 nm and greater than or equal to 0.5 nm; forming a photoresist layer over the base layer, the photoresist including a first side and an opposite second side; exposing a first portion of the photoresist layer to a pattern of extreme ultraviolet (EUV) radiation from the first side; exposing a second portion of the photoresist layer with a pattern of electron flux from the second side, the electron flux being directed into the photoresist layer from the base layer in response to the EUV radiation; developing the exposed photoresist layer to form a patterned photoresist layer; and transferring the pattern of the patterned photoresist layer to the base layer and the top layer.