1
- 2 - 3
- 4 
PhosPlus
Sources Have Widespread Uses
 PhosPlus
planar diffusion sources represent a significant advancement
in the field of phosphorus dopant materials. Their ability
to easily and uniformly dope large-diameter silicon wafers
in a safe manner accounts for their increasing popularity
in the semiconductor industry. In general, PhosPlus sources
offer all the advantages traditionally associated with planar
sources plus they possess a number of additional improvements
which make them the most desired phosphorus source available
to the diffusion engineer.
Two
PhosPlus Sources Provide Versatility
Two
PhosPlus sources are available to meet the many silicon processing
requirements of the semiconductor industry. The following
temperature ranges are normally recommended for their use:
Source
Type |
Recommended
Temperature Range, °C |
Appromiate
Sheet Resistivity  |
TP-470 |
950-1150 |
<1-7 |
TP-250 |
800-950 |
5-100 |
Each
type of PhosPlus source contains P2O5
and the extremely stable oxides of Ta2O5,
Al2O3 and/or La2O3.
The sources are manufactured in such a way that the P2O5
is combined with Al2O3 or La2O3,
and it only evolves when the sources are heated to the doping
temperatures through one of the following decomposition reactions:
Several
thin radial slots are cut into the sources to ensure that
they will not fracture when rapidly heated in the diffusion
furnace. The slots have no effect on the uniformity of the
doped silicon wafer. The TP-470 sources also contain Ta2O5
to adjust their thermal expansion coefficients and make them
extremely resistant to thermal shock.
PhosPlus
Sources Exhibit High Purity
The
PhosPlus sources are manufactured from raw materials exhibiting
very high purity. These materials are made using special processing
techniques developed at Techneglas, Inc. A typical impurity
analysis of a source when measured on a spark source mass
spectrograph.
| Metal |
PPM |
Metal |
PPM |
| Na |
1 |
Pt |
<2 |
| K |
<1 |
Rh |
<2 |
| Li |
<1 |
As |
<0.2 |
| Fe |
<2 |
B |
<5 |
| Pb |
<1 |
Sb |
<0.5 |
| Cr |
<2 |
Bi |
<0.5 |
| Cu |
<1 |
V |
<1 |
| Sn |
<1 |
Co |
<2 |
| Zn |
<2 |
Mo |
<1 |
| Ti |
<1 |
Ca |
<1 |
| Ni |
<2 |
Sr |
2 |
| Ag |
<1 |
Mn |
<1 |
| Au |
<0.5 |
Th |
<1 |
| Ba |
2 |
U |
<1 |
Are
Safe to Use
PhosPlus
sources are made of materials that are nontoxic, and they
evolve only P2O5 during use. Special
safety equipment and alarm systems that detect very low levels
of highly toxic gases, therefore, are not required.
1
- 2 - 3
- 4
|
