Browse Prior Art Database

Improved Hazardous Gas Cabinet

IP.com Disclosure Number: IPCOM000048801D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 4 page(s) / 58K

Publishing Venue

IBM

Related People

Pateyron, A: AUTHOR [+3]

Abstract

In the semiconductor industry, most of the manufacturing lines involve the use of either highly toxic gases (e.g., phosphine, arsine) or pyrogenic gases (e.g. silane). This raises the complex problem of the safe storage of hazardous gas cylinders while in service. The manual purge systems are complicated for safety reasons. Therefore, there is a need for an improved cabinet where all purge features are automatically performed, thereby limiting the risk of human error while being simple to service.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 4

Improved Hazardous Gas Cabinet

In the semiconductor industry, most of the manufacturing lines involve the use of either highly toxic gases (e.g., phosphine, arsine) or pyrogenic gases (e.g. silane). This raises the complex problem of the safe storage of hazardous gas cylinders while in service. The manual purge systems are complicated for safety reasons. Therefore, there is a need for an improved cabinet where all purge features are automatically performed, thereby limiting the risk of human error while being simple to service.

These objectives are achieved with the proposed gas cabinets, including some interesting features among which the control box provides a significant improvement.

The silane gas cabinet is depicted in Fig. 1A. It includes the following features:
Individual metal cabinet
Upper door (1/3) with transparent part
Lower door (2/3)

Air intake at bottom of lower door Exhaust pipe on top of cabinet
Cylinder strapped by chain
System to set the appropriate height of the cylinder.

The phosphine gas cabinet is depicted in Fig. 1B. It includes the following features:
Individual metal cabinet
Leak-proof cabinet
Transparent part on door
Air intake at bottom of lower door which is shut when exhaust is off (pneumatic)

Exhaust pipe on top of cabinet Cylinder strapped by chain.

System to set the appropriate height of the cylinder.

The operation (gas distribution and purge) may be understood from Fig. 2.

Gas distribution is accomplished by the following elements: Valves 1 and 2 are high pressure, pneumatic ball valves, normally closed. Valve 1 is at the output of the gas cylinder, and is actuated by the equipment when gas is needed. it shuts off if any incident occurs (see below discussion on the control box). Valve 2 is actuated by purge switches/button (see below discussion on purging).

Valves 3, 4 and 5 are standard pneumatic valves, normally closed.

Pressure regulator 6 (with pressure relief valve) lowers gas high pressure from cylinder (up to 200 bars usually) to servicing pressure (2 bars usually). Read-out of cylinder high pressure is available on the equipment for the user's convenience.

Pressure switch 7 detects overpressure on the low pressure side,

1

Page 2 of 4

if pressure regulator fails (set at 5 bars).

Restrictor 8 on the cabinet output allows limited gas flow to equipment (safety).

Pneumatic valves 2 and 5 allow nitrogen flow for purging.

Restrictor 9 is used (valve 5 closed) while "cylinder change purge" is on (see purge cycle table) in order to prevent too much nitrogen flow while connecting a new cylinder.

Check valve 10 prevents high pressure hazardous gas from flowing to nitrogen circuit.

Pneumatic valve 3 is used to vent tubing while "automatic purge" is on (see discussion on purge cycles below).

Outside the gas cabinet is the control box which includes: 24 VDC power supply
Alarm relays
Gas distribution relay
Purge relays
Electrical valves actuating pneumatic valves inside gas cabinet.

The control box may d...