BTU INTERNATIONAL

BTU’s quartz lined furnaces have been optimized for phosphorus diffusion, in-line processing of solar cells. Our unique fused quartz lined process chamber design, thermal uniformity and atmosphere control, combine into a high throughput, in-line solution. The quartz lining creates a metal-free processing tunnel design which eliminates the reaction with phosphoric acid. The systems come in two conveyor belt widths and varying heating lengths to meet the throughput requirements for today’s in-line processing. Belt widths include 20 in. (51 cm) and 36 in. (92 cm).

20 INCH

36 INCH

36 INCH

Maximum Temperature

1050 °C

Heated Zones

10

8

16

Heated Length

180 in. (4.6 m)

192 in. (4.8 m)

384 in. (9.7 m)

Conveyer Width

20 in. (508 mm)

36 in. (914 mm)

36 in. (914 mm)

Belt Material

Nichrome V

Atmosphere

Nitrogen/Air

Tunnel Material

Fused Quartz Plates

Cooling

66 in. (167 cm) Water

84 in. (213 cm) Water

108 in. (274 cm) Water

Diffusion is used in the manufacture of solar cells. Silicon wafers are doped with phosphoric acid to create the n-junction of the solar cell. This process is accomplished by depositing phosphorous vapor or coating to a silicon substrate. It is fired at temperatures between 800 °C and 1000 °C to drive the phosphorous into the silicon. Thus, creating the n-junction.
This application is typically processed in either a batch tube furnace or an in-line continuous furnace. The in-line approach offers far greater throughput opportunity than the batch process. BTU offers it’s quartz muffle furnaces for high throughput, in-line processing.