Metal Deposition for Thin-Film Research (Sputtering & Evaporation)

Metal Deposition on Wafers and Research Substrates

Metal deposition creates thin films that serve as electrodes, ohmic contacts, interconnects, seed layers, and reflective coatings. In research and prototyping, the goal is usually not “maximum throughput” — it is repeatability: stable film thickness, clean interfaces, consistent sheet resistance, and reliable adhesion from run to run.

UniversityWafer supplies the wafers and substrates commonly used for metallization workflows, including silicon, sapphire, quartz, fused silica, SiC, and glass. Your substrate choice (material, thickness, polish, and cleanliness) strongly influences adhesion, film stress, and patterning yield.

Processes: Sputtering vs. Evaporation

Most lab and pilot-line metal films are deposited by sputtering or evaporation. Both can produce excellent films — the best choice depends on the metal, film thickness, step coverage needs, and whether you are optimizing for adhesion, density, or purity.

Sputtering

Sputtering uses a plasma to eject atoms from a target and deposit them onto the substrate. It is often selected for films where good adhesion, dense microstructure, and uniformity are priorities. RF sputtering is common for insulating targets; DC sputtering is common for conductive targets.

• Strengths: dense films, strong adhesion, good uniformity for many materials
• Common uses: adhesion layers (Ti, Cr), diffusion barriers, refractory metals, multilayer stacks
• Notes: stress and heating can be higher; process parameters strongly affect film properties

Evaporation (Thermal and E-beam)

Evaporation deposits metal by vaporizing a source (thermal boat/crucible or electron beam) and condensing it on the substrate. It is widely used for clean, high-purity conductive films and straightforward metallization.

• Strengths: high purity, fast deposition for many noble/conductive metals
• Common uses: Au, Al, Ag, Cu, Pt layers; lift-off-friendly metallization
• Notes: step coverage depends on geometry; adhesion layers are frequently needed

Common Metals and Multilayer Stacks

Thin-film stacks are chosen to achieve the right combination of conductivity, adhesion, chemical stability, and compatibility with your downstream lithography and anneals.

• Conductive metals: Au, Al, Ag, Cu, Pt
• Adhesion layers: Ti or Cr (often placed under Au)
• Refractory / high-temperature metals: Mo, W (application dependent)
• Popular stacks: Ti/Au, Cr/Au, Ti/Pt/Au (contacts, pads, probes, mirrors)

Why adhesion layers matter

Gold is highly conductive and chemically stable, but it does not always adhere well to oxides and many glasses. A thin Ti or Cr layer underneath Au is a common way to improve adhesion and make patterned films more robust.

Adhesion, Stress, and Film Quality Tips

• Cleanliness: residues from handling, photoresist, or organics can cause peeling or high contact resistance.
• Surface condition: polish quality and native oxide state can affect adhesion and variability.
• Stress control: sputtered films can be compressive or tensile depending on pressure/power; stress impacts curl and cracking.
• Thermal budget: choose metals and substrates that can tolerate your anneal or operating temperature.
• Measurement: thickness (profilometry/ellipsometry), sheet resistance (4-point probe), and adhesion tests help validate repeatability.

Substrates Commonly Used for Metal Deposition

The “right” substrate depends on electrical isolation needs, optical transmission, RF loss, and temperature limits. Below are common choices used across thin-film labs:

• Silicon (Si): standard microfabrication platform; often used with thermal oxide when insulation is needed
• Sapphire (Al₂O₃): insulating, optically transparent, and thermally robust
• Quartz / Fused Silica: optical and low-loss RF applications; excellent chemical stability
• Silicon Carbide (SiC): high-power and harsh-environment devices
• Glass (soda-lime, borosilicate, aluminosilicate): cost-effective prototyping and transparent stacks

What to Specify When Requesting a Quote

Whether you are sourcing bare substrates for deposition or requesting pre-metallized coupons, you’ll get faster, more accurate quoting if you include:

• Substrate material: silicon, sapphire, quartz, fused silica, SiC, glass (and any coating already present)
• Size and thickness: diameter (e.g., 2"–8"), thickness range, and any flat/notch requirements
• Surface finish: SSP/DSP, epi-ready, or optical polish as needed
• Metal stack: metal(s), order (e.g., Ti/Au), and target thicknesses (e.g., 10 nm / 100 nm)
• Patterning method: lift-off vs etch (helps decide deposition geometry and thickness)
• Quantity and timeline: number of pieces, lead time, and any packaging/cleaning requirements

If you’re unsure which substrate is best for your deposition workflow, send your device goal and process notes we’ll help you narrow down the right material, size, and surface finish.