Material Deposition and Characterization (YIG, Permalloy, Cu, Ti, Pt etc)

Thin-film deposition and characterization of materials (metals, dielectrics, magnetic), annealing, AFM, VSM, XRD among other analyses.

Overview

I have done deposition and characterization of magnetic thin films, specifically Yttrium Iron Garnet (YIG) and Permalloy (Ni₈₀Fe₂₀), and other materials such as Cu, Ti, Pt for use in magnonic, spintronic, optoelectronic and MOS devices.
I utilized RF and DC sputtering followed by annealing, and performed AFM, vibrating sample magnetometry (VSM), etc**, and **XRD crystallographic verification**.

YIG and Permalloy Thin-Film Deposition

YIG and Permalloy films were deposited using a single-target sputtering system under controlled pressure and power conditions. Below are some sputtering parameters, they can vary vastly depending on specific sputtering chamber/setup.

  • YIG deposition: RF sputtering on GGG or Si substrates
  • Permalloy deposition: DC sputtering on Si/SiO₂ substrates
  • Base pressure: 3 × 10⁻⁶ Torr
  • Working pressure: 5 mTorr in Ar
  • Power: 70-80 W (RF), 60 W (DC)
  • Tips and Tricks:
  1. Using Cu backing plate with YIG target minimize the risk of target cracking.
  2. Use 20 mils thick permalloy target instead of 0.25” thick target. Because, thicker target have difficulty striking the plasma due to strong ferromagnetism of permalloy.
Thin-film deposition workflow: Test wafers (left), YIG Target(middle), and YIG RF sputtering (right).

Surface Morphology and Annealing

  • Deposition thickness of YIG films was inspected using Atomic Force Microscopy (AFM).
  • To crystallize the amorphous YIG layer, samples were annealed at 850 °C for 3–4 hours in ambient oxygen, followed by controlled cooldown to room temperature.
AFM morphology of as-deposited YIG film (top left) and thermal annealing in an oven (top right). Bottom: Photoresist profile of sputtered YIG.

Magnetic and Structural Characterization

After annealing, films were characterized using Vibrating Sample Magnetometry (VSM) and X-ray Diffraction (XRD):

  • VSM: Measured in-plane (IP) and out-of-plane (OOP) hysteresis (M–H) loop, revealing magnetic hysteresis and low coercivity.
  • XRD: 2θ–ω scans confirmed polycrystalline YIG peaks and phase purity after high-temperature annealing.
Magnetic and structural characterization of annealed YIG: (left) VSM M–H loop; (right) XRD confirming crystalline YIG phase.

Additional Fabrication Work

  • Sputtering deposition of Ti, Cu, Pt, Al, TiN, and other metallic layers for device contacts
  • ALD growth of Al₂O₃ for dielectric isolation and surface passivation
  • Integration of multilayer stacks combining magnetic, metallic, and dielectric films
  • Optimization of thickness control, adhesion, and uniformity across different substrates
  • Supported process development for hybrid magnonic, photonic, and spintronic device fabrication

Tools & Facilities