PhosPlus (R) Brochure
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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.


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