The term e-beam (electron beam) resist refers to a type of photoresist used in e-beam and deep ultraviolet applications. They can fabricate masks for highly integrated circuits, be involved in electron beam direct writing, and be used for multi-layer processing processes. E-beam resists work by changing the solubility of the resist in the developer, leaving the desired pattern on the resist surface. Currently, e-beam lithography using e-beam resists offers a promising alternative to UV lithography.
- E-beam lithography process flow
E-beam lithography is the process of directly drawing or projecting patterns onto a wafer coated with a photoresist with an E-beam. It has high resolution, a short production cycle, and easy pattern generation and modification. E-beam lithography is the most cost-effective option for manufacturing high-resolution graphics since it can achieve critical dimensions quickly and easily. The typical process flow in e-beam lithography is as follows: pre-baking, coating, soft-baking, exposure, post-baking, developing, and hardening. Fig. 1 illustrates a simple process flow in which e-beam resist plays an important role.
Fig. 1 A simple process flow in e-beam lithography (EBL) [1].
Classification of E-beam Resists
E-beam resist is a photoresist that sensitive to electrons, and the chemical properties of the exposed part change after scanning by e-beam because the resist undergoes molecular chain recombination. Therefore, the properties of e-beam resists are mainly affected by materials. According to the materials, e-beam resists can be classified as polymethylmethacrylate (PMMA) resists, dendritic resists, and molecular glass resists [2]. The first two are polymer-based resists.
E-beam lithography requires a photoresist with high sensitivity, high contrast, and anti-dry etching selectivity. The earliest developed e-beam resist applied PMMA as a resin system. The PMMA resist exhibits excellent resolution, strong adhesion, a mature and simple process with high stability, and low cost. Under e-beam irradiation, PMMA's main chain is broken to form low-molecular-weight polymers. However, PMMA has poor etching resistance and low sensitivity, so chemical amplification technology is generally used to compensate for PMMA shortages. Alternatively, adding electron-withdrawing groups to PMMA to prepare e-beam resists based on PMMA derivatives is also a suitable method.
Fig.2 Chemical structure of PMMA [1].
In addition to PMMA, dendritic polymer is also a good choice for a polymer-based resist. A dendritic resist uses dendritic polymers, which are based on triphenyl skeletons connected by chemical bonds to other phenyl groups. This type of e-beam resist is generally a chemically amplified photoresist that is composed of dendritic polymers and PAGs, and can achieve a minimum line resolution of 100 nm. Fig. 3 shows two typical dendritic resists [3].
Fig.3 Typical dendritic resists for e-beam lithography [3].
Molecular glass resist is an amorphous small molecule compound that can form a uniform and dense amorphous film. It is one of the promising candidates for advanced lithography due to its advantages such as explicit molecular structure, low molecular weight, monodispersity, high thermal stability, high glass transition temperature, and amorphous state [4]. The e-beam resist based on the molecular glass system is better than polymer materials with too large molecular weights, wide molecular weight distributions, and chain entanglement for high resolution and low line edge roughness.
Our Products
Alfa Chemistry is dedicated to providing customers with a range of high-performance E-beam resists. These products primarily include:
| Catalog Number | Type | Thickness Range | Resolution | Applicable Process | Key Features |
| PR-ER-0001 | Positive photoresist | 30-2000 nm | ≤10 nm | High-resolution nanostructures, lift-off processes | High resolution (sub-10 nm) and low cost, but low sensitivity (300–1000 μC/cm2), requiring high exposure dose. |
| PR-ER-0002 | Positive photoresist | 10-300 nm | 10-30 nm | High-sensitivity scenarios replacing PMMA | Benzene-ring-based structure with 3–5× higher sensitivity and 5× stronger dry-etch resistance compared to PMMA, with minimal residue after development. |
| PR-ER-0003 | Negative photoresist | 30-950 nm | ≤7 nm | Silicon etching masks, high aspect ratio structures | Inorganic siloxane structure with a resolution of 7 nm and line-edge roughness as low as 4.6 nm, without the need for dissolution during development. |
| PR-ER-0004 | Positive photoresist | 50-2000 nm | ≤10 nm | Sub-10 nm patterning, dry-etch resistance | Chemically amplified resist with high aspect ratio (20:1), excellent process stability, and low Young’s modulus, prone to collapse. |
| PR-ER-0005 | Negative photoresist | 30-950 nm | ≤20 nm | Dry etching masks | HF-etch resistant, capable of achieving line widths below 20 nm. |
| PR-ER-0006 | Positive photoresist | 80-1500 nm | 5-20 nm | Mask fabrication, metal lift-off | Available in multiple molecular weights (80K–1000K), excellent film-forming properties, and compatible with low acceleration voltages (30 kV). |
| PR-ER-0007 | Positive photoresist | 1-5000 nm | 20-100 nm | Electron beam lithography, graphene transfer | Linewidths below 100 nm with strong adhesion to the substrate, supporting multilayer T-gate lift-off processes. |
| PR-ER-0008 | Negative photoresist | 30-1000 nm | 30-100 nm | Thick dielectric layers, hybrid exposure processes | Chemically amplified resist with medium sensitivity (6–90 μC/cm2) and strong plasma-etch resistance. |
Process Selection Recommendations
Super-resolution nanostructures: PR-ER-0002 and PR-ER-0003 are recommended.
High aspect ratio masks: PR-ER-0004 is preferred.
Cost-sensitive applications: PR-ER-0001 is recommended.
Alfa Chemistry provides a variety of E-beam resists that combine outstanding resolution, high sensitivity, and consistent process performance, enabling both advanced research and large-scale industrial production to achieve accurate and reliable patterning results. If you are interested in our products, please feel free to contact us.
References
- Gangnaik, A. S.; et al. New generation electron beam resists: a review. Chem. Mater. 2017, 29(5): 1898–1917.
- Li, H.; et al. Research progress of matrix resin for electron Beam Lithography Photoresist. Information Recording Materials. 2016, 17(1).
- Tully, D. C.; et al. Dendrimers with thermally labile end groups: an alternative approach to chemically amplified resist materials designed for sub-100 nm lithography. Adv. Mater. 2000, 12(15): 1118-1122.
- Wang, Y.; et al. Negative-tone molecular glass photoresist for high-resolution electron beam lithography. R Soc Open Sci. 2021, 8(3): 202132.
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