Non-contaminating gas-tight valve for semiconductor applications

• US 6,435,474 B1
• Filed: 06/30/2000
• Issued: 08/20/2002
• Est. Priority Date: 06/30/2000
• Status: Expired due to Term

• Current Assignee: GlobalWafers Co., Ltd. (Sino-American Silicon Products Incorporated)
• Original Assignee: SunEdison, Inc.
• Inventors: Andrus, Treaf, Williams, Dick Stetson, Harrell, Ken, Kulage, Timothy J.
• Primary Examiner(s): Morris, Lesley D.
• Assistant Examiner(s): KEASEL, ERIC S
• Application Number:
  US09/608,304
• Time in Patent Office: 781 Days
• Field of Search: 251/315.03, 251/315.04, 251/315.05, 251/314, 251/316, 251/317, 251/368, 222/554, 137/375, 137/237, 137/238, 414/195, 414/209, 414/216
• US Class Current: 251/315.05
• CPC Class Codes: F16K 5/0657 Particular coverings or materials
• CPC Class Codes: F16K 5/0668 Single packings
• CPC Class Codes: F16K 51/02 specially adapted for high-vacuum installations
• CPC Class Codes: Y10T 137/4238 With cleaner, lubrication added to fluid or liquid sealing at valve interface

Abstract

A non-contaminating gas-tight valve for controlling a flow of granular polysilicon. The valve has a spherical valve member formed from single-crystal polysilicon, so that any particles worn from the valve member during use will be non-contaminating polysilicon. The valve member has a passage through which granular polysilicon flows when the valve is in an open position. When rotated perpendicular to the flow, the passage no longer permits movement of granular polysilicon through the valve. The valve member has a smooth finish and is wiped clean when rotated against non-abrasive upper and lower seats, reducing the likelihood of valve member wear. A cavity between the valve member and the valve body allows for removal of excess granular polysilicon from the valve, inhibiting the valve from seizing due to excess granular polysilicon slipping past the upper valve seat and accumulating within the valve. The valve additionally forms a gas-tight seal between an upstream and downstream side of the valve.

Claims

1. A valve apparatus for controlling a flow of granular polysilicon, which inhibits contamination of the granular polysilicon by foreign materials, the valve apparatus comprising:

a valve body having an inlet, an outlet, and a passage extending between the inlet and outlet for flow of granular polysilicon through the valve body;

a movable valve member substantially spherical in shape and disposed in the passage within the valve body for regulating the flow through the valve body, said movable valve member having highly polished surfaces exposed to engage the granular polysilicon formed from single-crystal silicon to reduce valve wear and inhibit creation of particulate contaminants within the flow of granular polysilicon, said surfaces further inhibiting erosion and ensuring that any erosion of the surface will be non-contaminating, said movable valve member has a cylindrical passage therein for allowing granular polysilicon to flow through the valve member, wherein said movable valve member is movable between an open position where the granular polysilicon may flow through the valve body and a closed position where the granular polysilicon cannot flow through the valve body; and

two annular seats, the movable valve member being seated against and rotatable with respect to the two annular seats, wherein one of said annular seats is an upper annular seat and the other annular seat is a lower annular seat, said upper annular seat being upstream of the movable valve member and said lower annular seat being downstream of the movable valve member, said valve member and the upper annular seat are sized and arranged within the valve body such that the annular seat has a tight fit against the valve member, and the valve, when closed, creates a gas tight seal between the inlet and outlet of the valve, wherein said valve body is further constructed to be substantially larger that the valve member such that there is an annular cavity between the valve member and the valve body, said annular cavity being outside the flow of granular polysilicon and acting as an overflow portion of the valve to keep excess granular polysilicon which may pass between the upper annular seat and the valve member from accumulating within the valve, causing the valve to seize, said lower annular seat having at least one drain hole in constant fluid communication with the annular cavity and the valve body passage for allowing excess granular polysilicon in the annular cavity to exit the valve body said valve apparatus being constructed with materials that render the valve apparatus operable over a pressure range of between about full vacuum to about 517 kilo-Pascals (75 pounds per square inch).

2. A valve apparatus as set forth in claim 1 wherein the upper annular seat further comprises a lip, engagement of the valve member with said lip during rotation of the valve member relative to the seat wipes the valve member clean.

3. A valve apparatus as set forth in claim 1 wherein said annular seats are formed from polytetrafluoroethylene.

4. A valve apparatus as set forth in claim 1 wherein said valve member is formed from single-crystal silicon to reduce wear of the valve member against the two annular seats and inhibit creation of metal particles or similar contaminants within the flow of granular polysilicon.

5. A granular polysilicon handling system for controlling a flow of granular polysilicon, the handling system comprising:

at least one material hopper sized and shaped to hold granular polysilicon within the system; and

at least one valve apparatus in fluid connection with the material hopper, the valve apparatus comprising;

a valve body having an inlet, an outlet, and a passage extending between the inlet and outlet for flow of granular polysilicon through the valve body;

a movable valve member substantially spherical in shape and disposed in the passage within the valve body for regulating the flow through the valve body, said movable valve member having highly polished surfaces exposed to engage the granular polysilicon formed from single-crystal silicon to reduce valve wear and inhibit creation of particulate contaminants within the flow of granular polysilicon, said surfaces further inhibiting erosion and ensuring that any erosion of the surface will be non-contaminating, said movable valve member has a cylindrical passage therein for allowing granular polysilicon to flow through the valve member, wherein said movable valve member is movable between an open position where the granular polysilicon may flow through the valve body and a closed position where the granular polysilicon cannot flow through the valve body; and

two annular seats, the movable valve member being seated against and rotatable with respect to the two annular seats, wherein one of said annular seats is an upper annular seat and the other annular seat is a lower annular seat, said upper annular seat being upstream of the movable valve member and said lower annular seat being downstream of the movable valve member, said valve member and the upper annular seat are sized and arranged within the valve body such that the annular seat has a tight fit against the valve member, and the valve, when closed, creates a gas tight seal between the inlet and outlet of the valve, wherein said valve body is further constructed to be substantially larger that the valve member such that there is an annular cavity between the valve member and the valve body, said annular cavity being outside the flow of granular polysilicon and acting as an overflow portion of the valve to keep excess granular polysilicon which may pass between the upper annular seat and the valve member from accumulating within the valve, causing the valve to seize, said lower annular seat having at least one drain hole in constant fluid communication with the annular cavity and the valve body passage for allowing excess granular polysilicon in the annular cavity to exit the valve body said valve apparatus being constructed with materials that render the valve apparatus operable over a pressure range of between about full vacuum to about 517 kilo-Pascals (75 pounds per square inch).

6. A granular polysilicon handling system as set forth in claim 5 further comprising conduit extending from the hopper for delivery of granular polysilicon, the valve apparatus connected to the conduit.