Home
EMULSITONE COMPANY
19 Leslie Court
Whippany, New Jersey 07981
TEL. (973)386-0053
FAX (973)503-0256
GOLDFILM
Goldfilm is designed for application with a spinner. After 10 or 15
seconds of spinning, a fairly hard film will form on the wafer which contains gold atoms
attached through suitable groupings to the carbon-carbon backbone forming the polymer. At
the selected diffusion temperature the polymer decomposes releasing gold to diffuse into
the wafer and CO2 and H2O which pass out the diffusion tube. The
gold concentration achieved does not depend upon the atmosphere selected for the
diffusion.
Application
Goldfilm is applied to the reverse (unpolished) surface of the wafer. When used as a
diffusion source, the concentration profile obtained is not dependent on the spin speed or
film thickness, because the gold concentration is sufficient that any continuous film will
supply enough gold to saturate the wafer. Goldfilm may also be used to deposit thin
metallic films on the reverse surface to facilitate child to package bonding. The metallic
film will vary with spin speed. At 6000 rpm a 20 angstrom thick film will result, while a
spin speed of 1000 rpm will yield a 100 angstrom film.
Diffusion Characteristics of Gold
The following data will be useful in determining the gold concentration which may be
obtained in silicon as a result of the diffusion process.
| Temperature (oC) | Gold Saturation Solubility (atoms/cm3) | Diffusion Coefficient (cm/Sec2) |
| 600 | 1014 | 2x10-10 |
| 800 | 1015 | 6x10-9 |
| 1000 | 8x1015 | 4x10-8 |
| 1100 | 1016 | 8x10-8 |
| 1200 | 5x1016 | 1x10-7 |
Lifetime Control
The trapping cross sections obtained with Goldfilm are similar to the values obtained with
evaporated or electroplated gold films. For reference, the following data shows the
reverse recovery time for a p-n junction in which the high resistivity side was n type:
| Diffusion temp. | tr (nanosecond) |
| 850oC | 17 |
| 1050oC | 3 |
| 1250oC | 0.3 |
Process For Plating Out Metallic Films
As noted above 20 to 100 angstroms of gold may be deposited as a continuous film on a
wafer by applying the material as directed. The wafer is then heated to 250o to
300oC. In 5 to 10 minutes film decomposition will occur, and a yellow film
characteristic of gold will result.
Doped Goldfilms
Goldfilm with Boron and Goldfilm with Phosphorous are handled in a manner similar to the
pure Goldfilm. These were designed for simultaneous gold and phosphorous or gold and boron
diffusion yielding a deep penetration of gold to create an intrinsic region and a p+
or n+ surface layer as required in PIN devices.
| Alphabetic Product Listing | Home |
|
Material Safety Data Sheet |