Sputter deposition

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Sputter deposition
Sputter Deposition.png
Technology Details
Technology PVD
Materials Ag, Al, Al2O3, Au, Cr, Cu, Fe, Ge, Ni, Pt, SiO2, Ti, TiO2, Zn

Sputter deposition is a physical vapor deposition method of thin film deposition in which a high-purity source material (called a cathode or target) is subjected to a gas plasma (typically argon). The energetic atoms in this gas plasma collide with the target material and knock off source atoms which then travel to the substrate and condense into a thin film.

Method of operation

Applications

Figures of merit

The figures of merit are described in the generic PVD page

Responses of figures of merit with parameter changes

Deposition Rate, Stress, Resistivity and Step Coverage

Although many films (especially reactive films and insulating compounds) may vary in their response, typical sputtering variables can be summarized in this trend chart:

Uniformity

Uniformity is set by the material being deposited and the geometry of the system: throw distance, target size, substrate rotation and deposition angle.

  • In sputtering, uniformity is determined by throw distance and the shape of the deposition cone.
    • In the Denton and Lab 18 tools, smaller sources eject material from the face of a 3" target that is angled to cover around 1/2 of the substrate area. The substrate is rotated to coat the entire area. Varying the angle will vary the throw distance and change the amount deposited on the center and edge. The supplies have a set throw angle that is optimized for best uniformity.
    • In the ALN tool, the wafer is centered over two targets which are larger than the substrate. Uniformity can be only be adjusted using the DC supply which raises and lowers the power to the center target.

Materials

The following materials can be deposited using Magnetron[clarification needed] sputter deposition at the LNF.

Equipment

The LNF has 4 sputter deposition tools

Lab 18-1

Main article: Lab 18-1
  • Materials Deposited: Al2O3, ITO, Mo, Si, SiO2, Si3N4, Ta, Ta2O5, Ti, TiO2
  • Lab 18-1 is a loadlocked magnetron sputter tool used for depositing metals, insulators, optical and semiconductive films. It has a variable-gated turbo pump and more sensitive gas flows that allow it to run more sensitive gas ratios (<1%) for reactive sputtering. It has a DC supply for conductive materials and RF supplies for electrically insulating materials. Deposition rates vary by material but are generally mich slower for RF depositions. The tool supports 5 materials at a time, rotated using the 18-1 Target Change Calendar

Lab 18-2

Main article: Lab 18-2
  • Materials: Al,Cr,Cu,Au,Ir,Ni,Pt,Ag,Ti
  • Lab 18-2 is a loadlocked magnetron sputter tool used for mostly for depositing metals. It uses DC for conductive materials and RF for electrically insulating materials. Deposition rates vary by material but are generally slower for RF depositions. The tool supports 5 materials at a time, rotated using the 18-2 Target Change Calendar

Denton Explorer

Main article: Denton Explorer
  • The Denton Explorer is an open-loop 2-source magnetron sputter tool used as a Lab 18 backup for depositing metal films

AMS 2004 Aluminum Nitride Sputter Tool

  • Materials deposited: AlN, Al
  • The AMS tool is designed specifically for Piezoelectric AlN on 4" wafers. It is a high temperature process that works only on certain substrates with specific seeding matetrials and the handler is only designed for 4" wafers are this time.

See also

Further reading