Facts
- The SMFL has two Nanometrics Spectrophotometers
- Nanometrics Model 210 is in Wet Etch 1.
- Nanometrics Model 200 is in Wet Etch 2
- The basic operating principle of a spectrophotometer is that the intensity of monochromatic reflected light depends strongly on film thickness because of interference.
- The film thicknesses are comparable to the wavelength of the incident light.
- The machine uses a computer-controlled grating monochromator and a photomultiplier tube detector to measure the reflected optical spectrum over the 350 to 800 nm wavelength band) from a bare silicon reference wafer and from the wafer under test.
- Given an index of refraction for a thin film and the two measured spectrums, the computer will analyze the interference pattern to determine film thickness.
Personnel
- Tool Engineer - Bruce Tolleson
- Process Engineer - Sean O'Brien
Tool & Process Information
- The Nanospec may be used to manually measure film thickness on wafers, wafer pieces or individual devices. Magnification ranges from 5x to 100x.
- If you do not see the octogon, make sure the aperture is closed.
- The filter should always be in, unless the tool tells you to take it out. (Nitride on Oxide)
- When measuring Thin Oxide or Thin Nitride, it is very important to carefully focus on the reference wafer as well as the sample, because the system is only measuring the intensity of a single wavelength.
| Program | Index | Range | Filter | |
|---|---|---|---|---|
| 1 | Oxide on Si | 1.45 | 400-30,000Å | In |
| 2 | Nitride on Si | 2.00 | 400-10,000Å | In |
| 3 | Negative Resist on Si | 1.55 | 500-40,000Å | In |
| 4 | Polysilicon on Oxide | 3.0 | 400-10,000Å | In |
| 5 | Negative Resist on Si | 1.55 | 4,000-30,000Å | In |
| 6 | Nitride on Oxide | 2.00 | 300-3,500Å | Out |
| 7 | Thin Oxide on Si | 1.45 | 100-500Å | In |
| 8 | Thin Nitride on Si | 2.00 | 100-500Å | In |
| 9 | Polyimide on Si | 1.78 | 500-10,000Å | In |
| 10 | Positive Resist on Si | 1.64 | 500-40,000Å | In |
| 11 | Positive Resist on Oxide | 1.64 | 4,000-30,000Å |