PECVD 1 (PlasmaTherm 790)

PECVD 1 (PlasmaTherm 790) Location Bay 3 Tool Type Vacuum Deposition Manufacturer Plasma-Therm Description PECVD Plasma Therm 790 For Oxides And Nitrides Primary Supervisor Michael Barreraz (805) 893-4147 mikebarreraz@ece.ucsb.edu Secondary Supervisor Don Freeborn Recipes Vacuum Deposition Recipes SignupMonkey: Sign up for this tool

About

Films: This is a Plasma-Therm model 790 plasma enhanced chemical vapor deposition system for depositing SiO₂, Si₃N₄, or SiO_xN_y dielectric films.

Hardware: The system uses a capacitively-coupled 13.56 MHz source excitation to produce the plasma between two parallel aluminum plates. The gas is injected over the sample through a 6” diameter showerhead. The samples are placed on the system anode (to minimize ion damage) which is heated to 250-350°C (250°C is standard).

Gases:

SiH₄ (Silane) is the Silicon precursor gas. It is diluted with He down to 2% Silane for safety.

N₂O is the Oxygen precursor gas, for producing SiO₂.

NH₄ is the Nitrogen precursor gas, for producing Si₃N₄.

CF₄ & O₂ are used for plasma-cleaning the chamber, by etching off deposited SiO₂/Si₃N₄ films from the chamber walls (in addition to wet-cleaning the chamber walls).

N₂ is available as a purging gas or carrier gas. A very low percentage of N₂ is expected to "crack" at the low RF powers used on this system.

Film Properties:

SiO₂ is produced from SiH₄/He 2%/98% and N₂O at 250°C. The typical deposition rate is 400 Å/min at 300 mT pressure. The typical BOE etch rate of this oxide is about 400 nm/min.

Si₃N₄ is produced from SiH₄/He 2%/98% and NH₃ at 250°C or 350°C. The more dense films are produced at 350°C. The stress of the nitride can be altered by adjusting the N₂:He ratio of the deposition.

Applications: These films are typically used for reactive ion etching masks, electrical insulators, chemical passivation layers, optical anti-reflective coatings and capacitor dielectrics. The system is fully programmable with windows-based software.

Usage: Users type in a deposition time for each recipe, using the published (or user-measured) deposition rates. Current dep rates for standard films can be found on the PECVD#1 process control data charts.

Custom programs for dielectric stacks or different process parameters or SiO_xN_y films can be written and saved.

Detailed Specifications

• Gases available: NH₃, N₂O, 2%SiH₄/He, N₂,CF₄ and O₂
• ~10mT base chamber pressure
• 13.56 MHz excitation freq.
  • Automatic tuning network
  • RF Power control
• Sample size: pieces to 6” wafers
• Full computer operation
• Standard recipes with deposition variable time

Documentation

• Operating Instructions
• Wafer Coating Process Traveler
• For particle counting method, see the Surfscan Scanning Procedure

Recipes & Data

• Standard Recipes: Recipes > Deposition > PECVD#1
  • A list of all available deposited films can be found here: Recipes > Vacuum Deposition Recipes
• Process Control Charts: Process Control > PECVD#1

Example Process Control Charts (SPC) for thin-film DepCals.

Example particle counts taken on each film.

Example of DepCals Thickness/Refractive Index uniformity measurement (4% shown here).