Claims
- 1. A load station for semiconductor wafers comprising:
- a chamber having an opening;
- means for supporting at least one cassette for holding semiconductor wafers oriented horizontally in said chamber,
- channel means comprising;
- first channel means for directing a horizontal flow of air into said chamber toward a cassette supported by said means for supporting and toward said opening and
- second channel means for directing a first stream of air to flow vertically
- downward into said chamber; and
- means for generating a second stream of air forming an air curtain having a velocity greater than the velocity of said first stream of air, said means for generating being capable of producing a downward velocity in said curtain of air sufficient to prevent said horizontal flow from penetrating said curtain of air so that the interior of said chamber is isolated from the environment external to said chamber opening;
- said channel means including air return slot means in said chamber for receiving air from said horizontal flow, said first stream and said second stream.
- 2. A load station as in claim 1 wherein said channel means includes means for filtering said horizontal flow of air and means for filtering said first stream of air.
- 3. A load station as in claim 2 wherein said means for supporting includes means for supporting a plurality of cassettes for holding semiconductor wafers oriented horizontally and said air return slot means comprises a slot located between at least two of said means for supporting for returning air to a means for generating moving air so that air is to said chamber through said means for filtering said horizontal flow and said means for filteirng said first stream of air.
- 4. A load station as in claim 3 wherein said chamber comprises a generally horizontal lower surface and said air return slot means comprises a slot in said lower surface for returning air receiving by said slot to said means for generating moving air.
- 5. A load station as in claim 1 including blower means for generating said horizontal flow of air and for generating said first stream of air.
- 6. A load station as in claim 5 wherein said blower means for generating comprises two air blowers in parallel.
- 7. A load station as in claim 5 wherein said blower means for generating comprises a first air blower for generating said first stream of air flowing vertically downward and a second air blower for generating said horizontal flow.
- 8. A load station as in claim 1 wherein said channel means comprises first duct means for connecting to an air supply system of a clean room so that air from said air supply means is supplied to said first channel means and said second channel means; and,
- second duct means for conveying air from said chamber to an exhaust port.
- 9. A load station as in claim 8 further including means for connecting said exhaust port to an air intake of said air supply of said clean room.
BACKGROUND OF THE INVENTION
This application is a continuation of application Ser. No. 126,656, filed 12-1-87, now abandoned.
1. Field of the Invention
This invention relates to semiconductor processing equipment and, in particular, to a load chamber providing selected air flow patterns for reducing particulate contamination.
As the trend toward higher device densities and smaller device geometries continues, particulate contamination has become an increasingly important problem. As is well known, a single particle on the order of one micron in diameter deposited on the surface of a semiconductor wafer can cause the loss of the entire wafer. One prior art approach to solving the particulate contamination problem has been to provide clean rooms for semiconductor processing. In the typical clean room, laminar air flows are generally directed downward from the ceiling of the clean room toward either floor or wall exhausts. The laminar air flows bathe the operator and the semiconductor equipment in filtered air. In some clean rooms, horizontal air flows from one clean room wall to an opposed clean room wall are provided.
The general approach of providing filtered air flows in clean rooms does not, however, solve the problem of particulate generation in areas which, by equipment design necessity, are sheltered from the clean room air flows. Once such area is the loading chamber region of many machines incorporating vacuum load locks. The load chamber is located externally of the load lock in the region adjacent the entrance to the load lock.
The present invention provides a load station for semiconductor processing apparatus which includes a load chamber having means for generating a horizontal flow of filtered air to bathe wafers held in the load chamber while simultaneously generating a vertical air curtain which flows across the entrance opening of the load chamber to isolate the horizontal flow generated in the load chamber from the clean room. In this manner the laminar downward flow of air in the clean room is not disturbed by the horizontal flow in the load chamber and the wafers in the load chamber are protected from particulate generation in the region above the wafer cassettes in the load chamber by the horizontal air flow.
In addition to the vertical air curtain, a laminar flow of filtered air directed vertically downward is also generated above the wafer cassettes, so that there are no regions of stagnate air in the load chamber. The horizontal flow merges with the vertical laminar downward flow. Air return slots are provided in the lower surface of the load chamber.
US Referenced Citations (20)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 134239 |
Oct 1980 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
| Parent |
126656 |
Dec 1987 |
|
Patent Grant
4927438
