At Nanosystems JP Inc. we offer SC1, SC2, RCA, piranha (SPM), and plasma cleaning for silicon wafers and compound substrates - plus photomask cleaning, large-format glass panel cleaning, and nanoimprint mold restoration. Cleaning coordinated as part of a complete fabrication engagement or as a standalone service.
Particulate contamination, organic residues, metallic impurities, and native oxide layers are present on every substrate surface before processing begins - and frequently between process steps. Nanosystems JP Inc. provides wet chemical cleaning for silicon, glass, fused silica, SiC, sapphire, and compound semiconductor substrates, as well as large-format glass panels and nanoimprint lithography molds. Cleaning can be supplied as a standalone incoming substrate preparation step, or coordinated as part of a broader fabrication engagement.
We offer the industry-standard RCA cleaning sequence and its individual components, as well as piranha (SPM) cleaning for heavy organic contamination and mold restoration. Chemistry, temperature, and sequence are tailored to substrate material and contamination type.
SC1 (Standard Clean 1), also called APM (Ammonium Peroxide Mixture), removes organic particles, small particulates, and some metallic contamination. The alkaline oxidant mixture lifts particles through surface charge repulsion and mild etching, then rinses clean in DI water. A primary step in the RCA cleaning sequence and frequently used as a standalone incoming substrate clean.
SC2 (Standard Clean 2), also called HPM (Hydrochloric-Peroxide Mixture), is the second step of the RCA sequence. It targets metallic ion contamination - particularly alkali metals and trace metal impurities from process equipment - by forming soluble metal chloride complexes that rinse away in DI water. Used following SC1 in a full RCA sequence or independently when metal contamination is the primary concern.
Piranha solution (SPM - Sulphuric-Peroxide Mixture) is a highly oxidizing mixture used for aggressive removal of thick organic contamination, photoresist residues, and carbonaceous films. It reacts vigorously with organic material and is the preferred chemistry for stripping heavily contaminated surfaces, restoring mold surfaces after nanoimprint cycles, and preparing substrates where SC1 alone is insufficient.
⚠ Piranha is a hazardous chemistry. Handling, disposal, and process conditions follow established safety protocols. Contact us to discuss your specific cleaning requirement and substrate compatibility.
The RCA cleaning sequence - developed at RCA Laboratories in the 1960s and still the semiconductor industry standard - combines multiple wet chemical steps to remove different contamination classes in sequence. We run standard and customised combinations depending on substrate material and contamination profile.
| Step | Name | Chemistry | Target Contamination | Notes |
|---|---|---|---|---|
| SPM / Piranha | Organic strip (optional) | H₂SO₄ : H₂O₂ (~3:1) | Heavy organics, thick resist residues | Used when gross organic contamination is present prior to SC1 |
| DHF | Dilute HF oxide strip | HF : DI H₂O (~1:50–1:100) | Native oxide, chemical oxide | Exposes bare silicon surface before SC1/SC2. Brief dip, immediately followed by rinse. |
| SC1 / APM | Standard Clean 1 | DI H₂O : NH₄OH : H₂O₂ (5:1:1) | Particles, organic residues | ~50°C, ~2 minutes. DI water rinse follows. |
| SC2 / HPM | Standard Clean 2 | DI H₂O : HCl : H₂O₂ (6:1:1) | Metal ion contamination | ~70°C. Removes alkali metals and trace metallic impurities. |
Sequence and chemistry concentrations are adjusted based on substrate material, device stage, and contamination type. Contact us with your process stage and substrate and we will confirm the appropriate clean sequence.
A typical standalone SC1 incoming substrate clean as run at Nanosystems JP Inc., suitable for silicon wafers and glass substrates prior to photolithography or thin film deposition:
Substrate immersed in APM solution (DI water : 29% NH₃ : 30% H₂O₂ = 5:1:1) at ~50°C. Removes organic particles and surface particulates via oxidative and mild alkaline etching mechanism.
Thorough overflow rinse in deionised water to remove chemical residues and lifted particles. Conductivity monitored to confirm complete rinse. Prevents re-deposition and neutralises residual alkalinity.
Substrate dried in vacuum oven at controlled temperature. Vacuum drying eliminates watermark formation (a common defect from spin or air drying) and removes residual moisture from surface and edges without mechanical stress.
Why vacuum oven drying: After wet chemical cleaning, conventional spin drying or air drying can leave watermark contamination - a form of surface oxide formed at the liquid-gas-solid three-phase boundary as water evaporates unevenly. Vacuum oven drying removes moisture uniformly without the centrifugal stress or evaporative residue risk of spin drying, producing a cleaner, contamination-free surface ready for the next process step.
Beyond standard round wafers, Nanosystems JP Inc. handles cleaning of large rectangular glass panels - borosilicate, soda lime, Eagle XG, and fused silica - up to 550×650mm. Panel-scale glass cleaning is a prerequisite for large-format photolithography, thin film deposition, and TGV fabrication, and is frequently required for display-process substrates repurposed for MEMS or sensor applications.
Note on glass chemistry: SC2 (HCl-based) and DHF steps used in standard silicon RCA sequences are not recommended for certain glass types due to surface attack. Chemistry selection for glass substrates is confirmed on a case-by-case basis against material specification. Contact us with your glass type and required cleanliness level.
Plasma cleaning is a fast, dry alternative to wet chemical cleaning for the removal of organic surface contamination, photoresist residues, and thin organic films from silicon wafers and compound semiconductor substrates. Oxygen plasma generates reactive species that oxidise and remove organic material without liquid chemicals or wet handling. At Nanosystems JP Inc., plasma cleaning is available as a pre-process surface preparation step, for photoresist descum between patterning steps, and for full resist ashing.
Oxygen plasma treatment removes thin organic contamination layers and surface hydrocarbon residues from silicon and compound semiconductor wafer surfaces. The process introduces polar functional groups and raises surface energy, improving wettability for subsequent spin coating, adhesive bonding, and thin film deposition steps. Particularly effective as a pre-lithography surface activation step to ensure uniform resist spreading and adhesion.
Descum is a brief, low-power plasma exposure that removes the thin residual photoresist layer that remains in nominally open areas of a wafer after resist development. These thin resist remnants - invisible to optical inspection - cause adhesion failures, etch blocking, and deposition irregularities if not removed. Plasma descum is routinely performed between development and etching or deposition to ensure a clean, residue-free substrate surface.
Full photoresist ashing removes the entire resist layer by exposing the wafer to oxygen plasma at sufficient power and duration to completely oxidise the resist film. Used as an alternative to solvent strip (acetone / NMP) when a solvent-free dry process is preferred, when resist has been hardened by ion implantation or deep UV exposure, or when cleanliness requirements rule out wet chemicals. After ashing, a brief wet clean (SC1 or piranha) is sometimes applied to remove any residual ash layer.
Plasma vs. wet cleaning: Plasma cleaning is not a replacement for RCA or piranha in all situations - it removes thin organic layers and activates surfaces but does not address metallic ionic contamination (that requires SC2/HPM) or thick oxide layers. The two approaches are often combined: wet chemical cleaning for bulk contamination control, plasma for final surface activation or residue removal before a critical process step.
Photomasks and reticles used in contact, proximity, or projection lithography accumulate organic haze, resist transfer residues, and particulate contamination over their service life. Mask cleaning is available as a standalone service or as part of a mask-to-wafer lithography engagement at Nanosystems JP Inc.
Standard photomask wet cleaning combines a piranha (SPM) strip to remove organic haze and resist transfer, followed by SC1 (APM) for particle removal, DI water cascade rinse, and vacuum oven drying. Suitable for chrome-on-glass (CoG) and chrome-on-quartz (CoQ) masks and reticles. Mask material and chrome layer compatibility are confirmed before processing.
Low-power oxygen plasma cleaning removes thin organic residues and haze from mask surfaces without liquid chemicals - useful for periodic maintenance between lithography runs and for masks where wet chemical exposure is not desirable. The process is gentle enough to avoid chrome layer damage at appropriate process conditions and leaves no liquid residue on the mask surface.
Mask cleaning note: Send us your mask type (CoG, CoQ, or quartz / fused silica), the current contamination (haze, resist residue, particles), and your mask dimensions and we will confirm the appropriate cleaning approach before processing. Masks handled with cleanroom-grade care throughout.
Nanoimprint lithography (NIL) molds accumulate residual polymer, imprint resist, and carbonaceous deposits over multiple imprint cycles. Effective mold cleaning is critical for maintaining feature fidelity and avoiding pattern transfer defects in subsequent imprint runs. Nanosystems JP Inc. provides two complementary mold cleaning approaches:
Piranha (SPM) solution is effective for dissolving bulk polymer and thick resist residues from mold surfaces. Used when organic loading is high - for example after multiple UV-NIL or thermal NIL cycles where resist residue has accumulated in mold cavities. The aggressive oxidising action of hot piranha removes carbonaceous material without physical abrasion that could damage fine mold features.
Oxygen plasma ashing is a dry cleaning method that removes thin organic films, residual polymer layers, and surface contamination through oxidative plasma chemistry. Unlike wet chemical methods, ashing leaves no liquid residue, is effective on molds with complex 3D topography, and can be applied repeatedly without the chemical handling concerns associated with piranha. Used for routine mold maintenance between production runs and for final surface activation prior to an imprint cycle.
Mold cleaning as a service: If you have a nanoimprint mold requiring cleaning or restoration - whether fabricated by us or externally - contact us with the mold material, feature dimensions, and contamination type and we will confirm the appropriate cleaning approach.
Cleaning can be provided as a standalone incoming substrate preparation step - you send us substrates, we clean and return - or as a coordinated step within a broader fabrication project. In either case, chemistry and sequence are confirmed against your substrate spec before processing.
Not all cleaning chemistries are compatible with all substrates. HF-based steps affect glass surfaces. Strong base concentrations can etch certain compound semiconductors. We confirm the cleaning sequence against your material before processing.
Panel-scale glass cleaning up to 550×650mm is available - matching our large-format photolithography and thin film deposition capability. Substrate cleaning for glass panels is coordinated as part of the full panel processing engagement or independently.
Cleaning is available for single wafers, small substrate batches, and individual molds. R&D quantities are standard - no minimum lot size requirement.
Share your substrate type, dimensions, contamination type, and process stage. A Nanosystems JP Inc. engineer will confirm the appropriate cleaning sequence and respond within 1 business day.
sales@nanosystemsjp.co.jp · NDA available on request · Response within 1 business day