In the relentless pursuit of miniaturization and performance enhancement in semiconductor technology, polymer materials have emerged as unsung heroes, enabling breakthroughs across every stage of chip fabrication. From lithography to packaging, these advanced polymers address critical challenges in resolution, thermal stability, and chemical resistance. This article delves into the multifaceted applications of polymers in semiconductor manufacturing, highlighting their transformative impact on the industry.
1. Lithography: The Art of Precision Imaging
Lithography is the cornerstone of semiconductor manufacturing, where polymers play a dual role as photoresists (light-sensitive films) and anti-reflective coatings (ARCs).
- Photoresists:
- Positive Resists: Dominant in modern processes, these resists (e.g., DNQ-phenolic resin systems) dissolve in developer solutions after exposure, creating precise patterns.
- Negative Resists: Utilize cross-linking reactions (e.g., cyclized rubber-diazonaphthoquinone systems) for cost-effective but lower-resolution applications.
- Chemically Amplified Resists (CARs): Leverage photogenerated acids to amplify sensitivity, enabling sub-10 nm features in KrF and ArF immersion lithography. For extreme ultraviolet (EUV) lithography, novel materials like metal oxide nanoparticles or molecular glass are under development.
- Anti-Reflective Coatings (ARCs):
- Bottom ARCs: Polymers like polyimide or spin-on carbon absorb stray light, reducing interference during exposure.
- Top ARCs: Acrylic polymers with light-absorbing groups prevent reflection from the photoresist surface.
2. Etching: Preserving Pattern Fidelity
During etching, polymers act as hard masks and sacrificial layers to ensure accurate pattern transfer.
- Hard Masks:
- Spin-on Carbon Layers: Derived from phenolic resins, these amorphous carbon films offer exceptional etch selectivity.
- Silicon Oxide Films: Formed via baking silicon-based polymers (e.g., silsesquioxanes), they provide thermal stability for high-temperature processes.
- Sacrificial Layers:
- Polyimide: Balances thermal stability, insulation, and chemical resistance for temporary protective coatings.
- PMMA: Widely used in lift-off processes due to its ease of dissolution in solvents.
3. Chemical Mechanical Planarization (CMP): Achieving Global Flatness
CMP relies on polished pads and slurries to flatten wafer surfaces. Key innovations include:
- Modified Polyurethane Pads: Engineered pore structures and hardness optimize material removal rates and uniformity. Companies like Rongchang New Materials and Entegris lead advancements in pad technology.
4. Thin-Film Deposition: Building Layered Structures
Polymers enable low-k dielectric materials and planarization:
- Spin-on Dielectrics:
- Polyimide Precursors: Converted to insulating films via imidization.
- BCB (BenzoCycloButene): Known for low k-values (<2.5) and excellent planarization.
- Nano-Porous Materials: Incorporating pores into polymers like SiLK (polyarylene ethers) further reduces dielectric constants.
5. Advanced Packaging: Protecting and Interconnecting Chips
Packaging demands polymers that withstand mechanical stress and thermal cycling:
- Encapsulants: Epoxy molding compounds (EMCs) dominate mainstream packaging, with suppliers like DaoYi Semiconductor pushing boundaries in fine-pitch filling and warpage control.
- Underfill Adhesives: Epoxy-based formulations mitigate thermal stress between chips and substrates.
- Temporary Bonding Films: Specialty polyimides or epoxies support thin-film processing before release.
- Flexible Substrates: Polyimide films offer heat resistance and flexibility for next-gen flexible electronics.
6. Ancillary Applications: Enabling End-to-End Manufacturing
Beyond core processes, polymers support ancillary functions:
- Electroplating Molds: Thick photoresists like SU-8 create deep trenches for copper interconnects.
- Cleaning Solutions: Removable acrylic coatings protect sensitive areas during wet etching.
- Wafer Handling: Specialty rubbers buffer mechanical stress in transport systems.
7. Critical Requirements and Challenges
Semiconductor polymers must meet stringent criteria:
- Ultra-High Purity: Metal impurities must be <1 ppt to avoid device failure.
- Thermal/Mechanical Robustness: Resist temperatures up to 400°C and plasma etching.
- Low Dielectric Constants: Critical for 3D integration and signal integrity.
- Nanoscale Precision: Line edge roughness <1 nm for EUV patterning.
8. Frontier Trends and Innovations
Emerging technologies are reshaping polymer material science:
- EUV-Compatible Materials: Molecular glasses and metal-oxide resists for sub-5 nm nodes.
- 3D Packaging: Polymers for through-silicon vias (TSVs) and fan-out packaging.
- Chiplet Integration: Thermally conductive adhesives and low-k interposers.
- Sustainability: Biodegradable polymers and recycling pathways for waste reduction.
9. Industry Collaboration and Innovation Hubs
Global initiatives like the 2025 SEMICON conference (Shanghai) and the AI Bang Semiconductor Polymer Forum (Wuxi, Oct 2025) foster collaboration. Topics such as PEEK/PPS applications, fluoropolymer corrosion resistance, and PFAS alternatives dominate discussions, reflecting the industry’s commitment to innovation.
The Polymer-Driven Future of Semiconductors
From defining nanometer-scale features to ensuring chip longevity, polymers are indispensable to semiconductor progress. As AI, HPC, and 5G drive demand for faster, smaller chips, polymers will continue evolving—ushering in an era of self-assembling monolayers, organic-inorganic hybrids, and molecular-scale engineering. The next frontier? Bridging the gap between lab breakthroughs and scalable manufacturing to sustain Moore’s Law beyond 2030.
In the precision manufacturing of modern semiconductor chips, polymer materials play an indispensable role. They are not only the medium of process realization, but also the key driver of continuous shrinkage of process technology.
The following are polymer materials that play an important role in the core process, if there are any deficiencies or omissions, everyone is welcome to add to them.
1. Lithography – the cornerstone of graphic transfer
1. Photoresist (photoresist):
Photoresists can be divided into EUV photoresists and ArF Dry and diffuse photoresists, KrF photoresists, etci/G line photoresist, which is the main imaging material, It has the ability to be sensitive to light at specific light wavelengths.
As a pattern carrier and mask material for pattern transfer to substrate, it is the most critical photoresist material.
2. Positive photoresist:
The exposed area is dissolved in a developer (e.g., DNQ-phenolic resin system). The lines are clear at the edges and occupy a mainstream position.
3. Negative photoresist:
Cross-linked curing of exposed areas (such as cyclic rubber-double azide system), dissolution of unexposed areas. Lower cost but limited resolution.
4. Chemically Amplified Photoresists:
The core material is PHS (poly-para-hydroxystyrene) and its derivatives. The use of photoacid catalysts to achieve “chemical amplification” greatly improves the sensitivity and resolution KrF and ArF are the mainstream of immersion lithography.
EUV photoresists require special designs (metal oxides or molecular glasses).
5. Anti-Reflective Coating:
- Anti-reflective coating at the bottom: Polyimide or spin-coated carbon materials are commonly used to absorb/eliminate incident light reflection and reduce standing wave effects.
- Top anti-reflective coating: mostly acrylate polymers containing light-absorbing groups, coated on the surface of the photoresist.
2 Etching process – guarantee of accurate reproduction of graphics
1. Hard Mask Material:
- Spin coated carbon layer: Polymer precursors (such as phenolic resins) are converted into amorphous carbon by high-temperature treatment, which has excellent etch selectivity.
- Spin-coated silica: Silicon-containing polymers (such as silicon sesquioxane) are baked to form SiO₂ -like films.
2. Etching barrier layer/peeling process sacrificial layer:
- Polyimide: High temperature resistance, excellent insulation and chemical stability.
- PMMA: Commonly used as a sacrificial layer material in stripping processes, it is easily soluble in specific solvents.
3 Chemical-mechanical grinding – the key to global flattening
Polishing pads: Typically made of modified polyurethane foam, their hardness, porosity, and elasticity directly affect the polishing rate and wafer surface uniformity.
4 Thin film deposition and planarization – construction of interlayer structures
Spin-coated dielectric material
- Polyimide precursors: imide after spin coating to form an insulating layer.
- Benzocyclobene: low dielectric constant, excellent flattening ability, low hygroscopicity.
- Porous low-κ materials: often found in SiLK(polyaryl ether) and other skeletons are introduced into the framework to reduce the dielectric constant.
5 Advanced packaging and chip protection
Encapsulation resin:
Epoxy molding compound picture taken at the SEMICON 2025 Daoyi Semiconductor Materials booth
Epoxy resin: mainstream material, low cost, good workmanship, reliable mechanical and insulation performance.
SiP technology trends require epoxy plastic encapsulants (EMC) to be suitable for slit gaps/excellent filling capacity for narrow spacing; Warping control; Resistant to delamination/solder extrusion, etc.
Polyimide: Used for stress buffer layers, passivation layers, and flexible substrates in high-end packaging.
Underfill adhesive: epoxy resin system, filling the gap between the chip and the substrate to relieve thermal stress.
Temporary bonding adhesives: Special polyimides or epoxy resins that provide support in thin wafer processing and are easy to peel off upon completion.
Flexible Substrate: Polyimide film is the core material, high temperature resistance, flexibility, and dimensional stability.
Photosensitive insulating dielectric material: Photosensitive polyimide or BCB for rerouting layers in fan-out packages.
6 Other ancillary applications
Plating molds: Thick photoresists, such as SU-8 epoxy, are used to create the deep groove structures required for plating.
Cleaning and protection: Acrylate protective coating can be peeled off.
Core requirements and challenges
1. Ultra-high purity: metal ion impurities need to be controlled at ppb or even ppt to avoid contamination and device failure.
2. Precise and controllable physical and chemical properties: molecular weight, molecular weight distribution, functional groups, glass transition temperature, etc. need to be highly uniform.
3. Extreme process resistance: high temperature resistance, plasma resistance, strong acid and alkali resistance and various solvent corrosion.
4. Nanoscale processing performance: Resolution, line edge roughness, and pattern fidelity are extremely high.
5. Low dielectric constant and loss: The interconnect layer material needs to reduce signal delay and crosstalk.
From photoresists drawing initial blueprints on silicon wafers to encapsulating resins to put on strong “armor” for chips, Polymer materials run through the entire chain of semiconductor manufacturing.
With continuous breakthroughs in process nodes (such as EUV lithography) and advanced packaging technologies such as 3D The rise of integrated chiplets has put forward more stringent requirements for polymer materials: higher resolution, lower dielectric constant, better thermomechanical properties and higher purity.
The research and development of new polymers (such as more advanced polyimides, self-assembly materials, molecular glass) and nanocomposites (such as polymer/inorganic hybrid materials) will continue to drive semiconductor technology to smaller, faster, stronger, More energy-saving direction.
On the precision stage of this microscopic world, polymer materials are playing an increasingly dazzling role.