Patent US3900597A successfully refreshed from Google Patents.
US3900597A
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US
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System and process for deposition of polycrystalline silicon with silane in vacuum
Assignee: Motorola Solutions Inc
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Filing: 1973-12-19
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Granted: 1975-08-19
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Expires: 1993-12-19
Abstract
Abstract The present invention is directed to the method and means for depositing polycrystalline silicon from silane in a vacuum. This process contemplates the use of a gas source and a means for assuring a uniform flow of gas into the deposition chamber. The deposition chamber is a hot wall furnace. The deposition zone is kept at as uniform a temperature as possible. The preferred temperature is 600*C with a workable range extending from 600*C to 700*C. While the deposition zone is profiled flat from a temperature point of view, the deposition rate over the length of the tube appears as a flattened curve. This means that at the source and exhaust portions of the tube, the deposition rates are different from that rate in the central flattened portion. The boat upon which the wafers are placed is centered within the center portion of the curve along its flattest portion. Wafers are placed perpendicular to the gas flow with a preferred spacing approximately 50 mils on center when using wafers 20 mils thick. The wafers are placed in the tube from the source input end. At the gas exhaust end, intermediate the tube and the vacuum pump, is an optical baffle. The function of the optical baffle is to collect the undeposited silane material and silicon by-products which pass through the tube. The undeposited silane material appears in the form of a brown dust which is granular silicon and silicon monoxide. This granular material forms around the exit end of the tube and in the baffle.
Inventors
- 👤 Jerry L Chruma
- 👤 Paul G Hilton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:29
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/40; H10P14/416; C; C23; C23C; C23C16/00; C23C16/22; C23C16/24; C23C16/44; C23C16/455; H10P14/20; H10P14/24; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; Y; Y10; Y10S; Y10S148/00; Y10S148/006; Y10S148/122
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
203 words
IN A METHOD FOR DEPOSITING POLYCRYSTALLINE SILICON MATERIAL ONTO A WAFER FROM A GASEOUS SILICON SOURCE FLOWING THROUGH A FURNACE TUBE, AND THE FURANCE IS PROVIDED WITH HEATING MEANS, AND IS FURTHER PROVIDED WITH A FIRST END THROUGH WHICH THE GASEOUS SILICON SOURCE IS ADMITTED INTO THE TUBE, AND IS FURTHER PROVIDED WITH A SECOND END FROM WHICH THE RESIDUAL GASEOUS SILICON IS EXHAUSTED, THE IMPROVEMENT COMPRISING THE STEPS OF: INTRODUCING A PLURALITY OF WAFERS INTO THE FURNACE THROUGH THE FIRST END, PLACING SAID PLURALITY OF WAFERS INTO THE STREAM OF GASEOUS SILICON SUCH THAT THE BROAD SURFACE OF EACH OF SAID WAFERS UPON WHICH THE POLYCRYSTALLINE MATERIAL IS TO DEPOSIT IS PLACED PERPENDICULAR TO THE DIRECTION OF THE GAS FLOW, SPACING THE WAFERS A MINIMUM OF 30 MILS BETWEEN ADJACENT SURFACE, HEATING THE WAFERS TO A TEMPERATURE UNDER 700*C FOR A TIME SUFFICIENT TO GROW THE DESIRED THICKNESS OF POLYCRYSTALLINE SILICON MATERIAL, ESTABLISHING A VACUUM AT THE EXHAUST END OF THE TUBE FOR DRAWING THE GASEOUS SILICON OVER THE WAFERS, CONTINUING THE FLOW OF THE GASEOUS SILICON FOR A PREDETERMINED PERIOD AND THEN CLOSING OFF THE FLOW OF SAID GASEOUS SILICON, AND WITHDRAWING SAID WAFERS FROM THE FURNACE BY SAID FIRST END.
Claim 2
Dependent Claim
203 words
IN A METHOD FOR DEPOSITING POLYCRYSTALLINE SILICON MATERIAL ONTO A WAFER FROM A GASEOUS SILICON SOURCE FLOWING THROUGH A FURNACE TUBE, AND THE FURANCE IS PROVIDED WITH HEATING MEANS, AND IS FURTHER PROVIDED WITH A FIRST END THROUGH WHICH THE GASEOUS SILICON SOURCE IS ADMITTED INTO THE TUBE, AND IS FURTHER PROVIDED WITH A SECOND END FROM WHICH THE RESIDUAL GASEOUS SILICON IS EXHAUSTED, THE IMPROVEMENT COMPRISING THE STEPS OF: INTRODUCING A PLURALITY OF WAFERS INTO THE FURNACE THROUGH THE FIRST END, PLACING SAID PLURALITY OF WAFERS INTO THE STREAM OF GASEOUS SILICON SUCH THAT THE BROAD SURFACE OF EACH OF SAID WAFERS UPON WHICH THE POLYCRYSTALLINE MATERIAL IS TO DEPOSIT IS PLACED PERPENDICULAR TO THE DIRECTION OF THE GAS FLOW, SPACING THE WAFERS A MINIMUM OF 30 MILS BETWEEN ADJACENT SURFACE, HEATING THE WAFERS TO A TEMPERATURE UNDER 700*C FOR A TIME SUFFICIENT TO GROW THE DESIRED THICKNESS OF POLYCRYSTALLINE SILICON MATERIAL, ESTABLISHING A VACUUM AT THE EXHAUST END OF THE TUBE FOR DRAWING THE GASEOUS SILICON OVER THE WAFERS, CONTINUING THE FLOW OF THE GASEOUS SILICON FOR A PREDETERMINED PERIOD AND THEN CLOSING OFF THE FLOW OF SAID GASEOUS SILICON, AND WITHDRAWING SAID WAFERS FROM THE FURNACE BY SAID FIRST END.
Claim 3
Dependent Claim
34 words
The method recited in claim 1 wherein the furnace tube and wafers are heated to the predetermined operating temperature before the gaseous silicon is passed into the furnace under the influence of the vacuum.
Claim 4
Dependent Claim
20 words
The method recited in claim 1, wherein the spacing of the wafers lies between 50 to 3,000 mils on center.
Claim 5
Dependent Claim
19 words
The method recited in claim 1 wherein the gaseous silicon source is selected from SiH4, SiCl2H2, SiCl3 and SiCl4.
Claim 6
Dependent Claim
28 words
The method recited in claim 1 wherein the wafer to be covered with polycrystalline silicon Is selected from silcion, germanium, sapphire, spinel, ceramic, silicon dioxide, tungsten and molybdenum.
Claim 7
Dependent Claim
33 words
The method recited in claim 1, and further includes the step of: providing a baffle at the exhaust end of the furnace tube for removing residual silane prior to entering the vacuum pump.
Claim 8
Dependent Claim
48 words
The method for depositing polycrystalline silicon as recited in claim 1, whrein after the step of closing off the flow of silane, the method further includes the step of: flushing with an inert gas any residual gaseous silane which remains between the silicon source and the vacuum source.
Claim 9
Dependent Claim
50 words
The method for depositing polycrystalline silicon as recited in claim 1, wherein after the step of closing off the flow of gaseous silicon, the method further includes the step of: establishing atmospheric pressure within the furnace tube by deactivating the vacuum source and introducing an inert gas into the tube.
Claim 10
Independent Claim
108 words
A method of forming a polycrystalline silicon layer upon a plurality of silicon wafers, comprising the steps of: placing a plurality of silicon wafers in a closed container; establishing a uniform temperature throughout a portion of the closed container, said temperature being less than 700*C, and said wafers being placed within the uniform temperature portion of the container; placing the wafers on end perpendicular to the flow of gas and spaced one from the other by a distance greater than 30 mils; and passing a gas stream of silane over the heated wafers under the motivation of a vacuum established between the range of 600 to 1,600 millitorr.
Claim 11
Independent Claim
108 words
A method of forming a polycrystalline silicon layer upon a plurality of silicon wafers, comprising the steps of: placing a plurality of silicon wafers in a closed container; establishing a uniform temperature throughout a portion of the closed container, said temperature being less than 700*C, and said wafers being placed within the uniform temperature portion of the container; placing the wafers on end perpendicular to the flow of gas and spaced one from the other by a distance greater than 30 mils; and passing a gas stream of silane over the heated wafers under the motivation of a vacuum established between the range of 600 to 1,600 millitorr.
Claim 12
Dependent Claim
242 words
In a method for depositing polycrystalline silicon material onto a wafer which has a layer of silicon dioxide formed on a first major surface of the wafer, and the silicon is obtained from a gaseous silane source flowing through a heated furnace tube, and the tube has a first end into which the gaseous silicon is added to the tube, and the tube is further equipped with a second end from which the residual gaseous silane is exhausted, the improvement comprising the steps of: introducing a plurality of wafers into the furnace through the first end of the furnace, and said wafers being oriented such that the first major surface of each wafer faces the first end of the furnace tube and is perpendicular to the direction of gas flow through the furnace tube, and said wafers are spaced more than 30 mils between adjacent surfaces; establishing a vacuum at the exhaust end of the tube to a level within the range of 600 to 1,600 millitorr for drawing gases through the furnace; introducing a flow of an inert gas into the tube while heating the wafers to a predetermined temperature under 700*C; upon reaching the predetermined temperature, shutting off the flow of nitrogen and exposing the silane to the effects of the vacuum; continuing the flow of silane for a predetermined period and then closing off the flow of silane; and withdrawing the wafers from the furnace by said first end.
Claim 13
Dependent Claim
242 words
In a method for depositing polycrystalline silicon material onto a wafer which has a layer of silicon dioxide formed on a first major surface of the wafer, and the silicon is obtained from a gaseous silane source flowing through a heated furnace tube, and the tube has a first end into which the gaseous silicon is added to the tube, and the tube is further equipped with a second end from which the residual gaseous silane is exhausted, the improvement comprising the steps of: introducing a plurality of wafers into the furnace through the first end of the furnace, and said wafers being oriented such that the first major surface of each wafer faces the first end of the furnace tube and is perpendicular to the direction of gas flow through the furnace tube, and said wafers are spaced more than 30 mils between adjacent surfaces; establishing a vacuum at the exhaust end of the tube to a level within the range of 600 to 1,600 millitorr for drawing gases through the furnace; introducing a flow of an inert gas into the tube while heating the wafers to a predetermined temperature under 700*C; upon reaching the predetermined temperature, shutting off the flow of nitrogen and exposing the silane to the effects of the vacuum; continuing the flow of silane for a predetermined period and then closing off the flow of silane; and withdrawing the wafers from the furnace by said first end.
Claim 14
Dependent Claim
48 words
The method for depositing polycrystalline silicon as recited in claim 10, wherein after the step of closing off the flow of silane, the method further includes the step of: flushing with an inert gas any residual silane which remains between the silane source and the source of vacuum.
Claim 15
Dependent Claim
50 words
The method for depositing polycrystalline silicon as recited in claim 10, wherein after the step of closing off the flow of silane, the method further includes the step of: establishing atmospheric pressure within the furnace tube by deactivating the vacuum source and introducing an inert gas into the furnace tube.
Claim 16
Dependent Claim
38 words
The method for depositing polycrystalline silicon as recited in claim 10, and further includes the step of: providing a baffle at the exhaust end of the furnace tube for removing residual silane prior to entering the vacuum pump.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |