US5316970A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Generation of ionized air for semiconductor chips
Assignee: International Business Machines Corp
•
Filing: 1992-06-05
•
Granted: 1994-05-31
•
Expires: 2012-06-05
Abstract
Abstract Ionization of air without the use of corona discharge tips, thereby to avoid the generation of particulates from corrosion of the corona tips, is accomplished by use of a laser beam focussed to a small focal volume of intense electric field adjacent a semiconductor chip. The electric field is sufficiently intense to ionize air. In the manufacture of a semiconductor circuit chip, during those steps which are conducted in an air environment, opportunity exists to remove from a surface of a chip, or wafer, charge acquired during the manufacturing process. The ionized air is passed along the chip surface. Ions in the air discharge local regions of the chip surface which have become charged by steps of a manufacturing process. By way of further embodiment of the invention, the ionization may be produced by injection of molecules of water into the air, which molecules are subsequently ionized by a laser beam and directed toward the chip via a light shield with the aid of a magnetic field.
Inventors
- 👤 John S. Batchelder
- 👤 Vaughn P. Gross
- 👤 Robert A. Gruver
- 👤 Philip C. D. Hobbs
- 👤 Kenneth D. Murray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:49
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0406; H05; H05F; H05F3/00; H05F3/06; Y; Y10; Y10S; Y10S430/00; Y10S430/138; Y10S438/00; Y10S438/909
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
131 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object by directing rays of the radiation along converging paths which bypass the object, the concentrating providing sufficient intensity of radiation to ionize the air; locating said focal volume at a side of the object to reduce illumination of a surface of the object by plasma in the focal volume, said step of locating including a locating of said focal volume adjacent an edge of the object to discharge the object by ions borne by the air; and flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object.
Claim 2
Independent Claim
131 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object by directing rays of the radiation along converging paths which bypass the object, the concentrating providing sufficient intensity of radiation to ionize the air; locating said focal volume at a side of the object to reduce illumination of a surface of the object by plasma in the focal volume, said step of locating including a locating of said focal volume adjacent an edge of the object to discharge the object by ions borne by the air; and flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object.
Claim 3
Dependent Claim
23 words
A method according to claim 1 wherein said step of concentrating the radiation provides for in-situ ionization of the air near the object.
Claim 4
Dependent Claim
40 words
A method according to claim 1 wherein said radiation is coherent radiation, and said step of illuminating comprises a step of activating a laser to produce a beam of said coherent radiation, and wherein said object is a semiconductor wafer.
Claim 5
Independent Claim
142 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object to provide sufficient intensity of radiation to ionize the air; flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object; locating said focal volume adjacent an edge of the object to discharge the object by ions borne by the air; wherein said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; and dispensing water molecules into said focal volume to become ionized by said radiation, ionized molecules of the water being carried by the air to provide said ionized air, said object being a semiconductor wafer.
Claim 6
Independent Claim
142 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object to provide sufficient intensity of radiation to ionize the air; flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object; locating said focal volume adjacent an edge of the object to discharge the object by ions borne by the air; wherein said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; and dispensing water molecules into said focal volume to become ionized by said radiation, ionized molecules of the water being carried by the air to provide said ionized air, said object being a semiconductor wafer.
Claim 7
Independent Claim
121 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object to provide sufficient intensity of radiation to ionize the air; flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object; wherein said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; and dispensing drops of a preionization threshold reduction material into said focal volume to become ionized by said radiation, ionized molecules of the water being carried by the air to provide said ionized air.
Claim 8
Independent Claim
121 words
A method for generating contamination-free ionized air for discharging an object comprising: illuminating a region of the air with radiation; concentrating the radiation in a focal volume adjacent the object to provide sufficient intensity of radiation to ionize the air; flowing the air past the object to bring ions of the ionized air in contact with charged regions on a surface of the object; wherein said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; and dispensing drops of a preionization threshold reduction material into said focal volume to become ionized by said radiation, ionized molecules of the water being carried by the air to provide said ionized air.
Claim 9
Dependent Claim
23 words
A method according to claim 5 wherein said step of concentrating the radiation provides for in-situ ionization of the air near the object.
Claim 10
Independent Claim
196 words
A method of manufacturing a semiconductor circuit on a chip wherein a structure of the circuit comprises a succession of layers of materials developed upon a substrate of a wafer, the method employing manufacturing steps of photolithography with deposition and etching of layers of material to be performed at different work stations, the method comprising: positioning said wafer at a work station; generation ionized air; contacting a surface of said wafer with the ionized air to discharge said surface; performing a manufacturing step upon said wafer at the work station; and wherein said generating step comprises the steps of: illuminating a region of air at said station with radiation; concentrating the radiation in a focal volume adjacent said wafer by directing rays of the radiation along converging paths which bypass the wafer, the concentrating providing sufficient intensity of radiation to ionize the air; and locating said focal volume at a side of the wafer to reduce illumination of a surface of the wafer by plasma in the focal volume, said step of locating including a locating of said focal volume adjacent an edge of the wafer to discharge the wafer by ions borne by the air.
Claim 11
Independent Claim
196 words
A method of manufacturing a semiconductor circuit on a chip wherein a structure of the circuit comprises a succession of layers of materials developed upon a substrate of a wafer, the method employing manufacturing steps of photolithography with deposition and etching of layers of material to be performed at different work stations, the method comprising: positioning said wafer at a work station; generation ionized air; contacting a surface of said wafer with the ionized air to discharge said surface; performing a manufacturing step upon said wafer at the work station; and wherein said generating step comprises the steps of: illuminating a region of air at said station with radiation; concentrating the radiation in a focal volume adjacent said wafer by directing rays of the radiation along converging paths which bypass the wafer, the concentrating providing sufficient intensity of radiation to ionize the air; and locating said focal volume at a side of the wafer to reduce illumination of a surface of the wafer by plasma in the focal volume, said step of locating including a locating of said focal volume adjacent an edge of the wafer to discharge the wafer by ions borne by the air.
Claim 12
Dependent Claim
32 words
A method according to claim 7 wherein said radiation is coherent radiation, and said step of illuminating comprises a step of activating a laser to produce a beam of said coherent radiation.
Claim 13
Independent Claim
181 words
A method of manufacturing a semiconductor circuit on a chip wherein a structure of the circuit comprises a succession of layers of materials developed upon a substrate of a wafer, the method employing manufacturing steps of photolithography with deposition and etching of layers of material to be performed at different work stations, the method comprising: positioning said wafer at a work station; generating ionized air; contacting a surface of said wafer with the ionized air to discharge said surface; performing a manufacturing step upon said wafer at the work station; and wherein said generating step comprises steps of: illuminating a region of air at said station with radiation; and concentrating the radiation in a focal volume adjacent said wafer to provide sufficient intensity of radiation to ionize the air; said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; dispensing drops of a preionization threshold reduction material into said focal volume to become ionized by said radiation, ionized drops being entrained in the air to provide said ionized air.
Claim 14
Independent Claim
181 words
A method of manufacturing a semiconductor circuit on a chip wherein a structure of the circuit comprises a succession of layers of materials developed upon a substrate of a wafer, the method employing manufacturing steps of photolithography with deposition and etching of layers of material to be performed at different work stations, the method comprising: positioning said wafer at a work station; generating ionized air; contacting a surface of said wafer with the ionized air to discharge said surface; performing a manufacturing step upon said wafer at the work station; and wherein said generating step comprises steps of: illuminating a region of air at said station with radiation; and concentrating the radiation in a focal volume adjacent said wafer to provide sufficient intensity of radiation to ionize the air; said radiation is coherent radiation, and said step of illuminating comprises: activating a laser to produce a beam of said coherent radiation; dispensing drops of a preionization threshold reduction material into said focal volume to become ionized by said radiation, ionized drops being entrained in the air to provide said ionized air.
Claim 15
Independent Claim
124 words
A method for generating contamination-free ionized air for discharging an object during a photolithographic process of manufacture of the object, the method comprising: concentrating coherent radiation optically in a focal volume said concentrating including a converging of rays of radiation to said focal volume; ionizing air by flowing the air via the focal volume to the object, the flowing of the air via the focal volume allowing the radiation to ionize the air; locating said focal volume adjacent an edge of the object for in-situ ionization of the air near the object by directing the rays of radiation to pass by the object; and discharging the object with ionized air obtained in said focal volume, said discharging being performed during said process of manufacture.
Claim 16
Independent Claim
124 words
A method for generating contamination-free ionized air for discharging an object during a photolithographic process of manufacture of the object, the method comprising: concentrating coherent radiation optically in a focal volume said concentrating including a converging of rays of radiation to said focal volume; ionizing air by flowing the air via the focal volume to the object, the flowing of the air via the focal volume allowing the radiation to ionize the air; locating said focal volume adjacent an edge of the object for in-situ ionization of the air near the object by directing the rays of radiation to pass by the object; and discharging the object with ionized air obtained in said focal volume, said discharging being performed during said process of manufacture.
Claim 17
Independent Claim
179 words
A method for generating contamination-free ionized air for discharging an object during a photolithographic process of manufacture of the object, the process of manufacture including a depositing of photosensitive material on a surface of the object, the method for generating contamination-free ionized air comprising: concentrating coherent radiation optically in a focal volume said concentrating including a converging of rays of radiation to said focal volume; ionizing air by flowing the air via the focal volume to the object, the flowing of the air via the focal volume allowing the radiation to ionize the air; locating said focal volume adjacent an edge of the object for in-situ ionization of the air near the object by directing the rays of radiation to pass by the object, there being a plasma in said focal volume emitting a further radiation; shielding the photosensitive material on the surface of the object from at least one of said coherent radiation and said further radiation; and discharging the object with ionized air obtained in said focal volume, said discharging being performed during said process of manufacture.
Claim 18
Independent Claim
179 words
A method for generating contamination-free ionized air for discharging an object during a photolithographic process of manufacture of the object, the process of manufacture including a depositing of photosensitive material on a surface of the object, the method for generating contamination-free ionized air comprising: concentrating coherent radiation optically in a focal volume said concentrating including a converging of rays of radiation to said focal volume; ionizing air by flowing the air via the focal volume to the object, the flowing of the air via the focal volume allowing the radiation to ionize the air; locating said focal volume adjacent an edge of the object for in-situ ionization of the air near the object by directing the rays of radiation to pass by the object, there being a plasma in said focal volume emitting a further radiation; shielding the photosensitive material on the surface of the object from at least one of said coherent radiation and said further radiation; and discharging the object with ionized air obtained in said focal volume, said discharging being performed during said process of manufacture.
Claim 19
Dependent Claim
46 words
A method according to claim 11 wherein said coherent radiation is produced as a beam from a laser, and said shielding from said coherent radiation is accomplished by installing an opaque shield between the laser beam and the photosensitive material on the surface of the object.
Claim 20
Dependent Claim
39 words
A method according to claim 11 wherein the surface holding the photosensitive material is planar, and said shielding from said further radiation is accomplished by positioning said focal volume behind a plane of the surface holding the photosensitive material.
Claim 21
Dependent Claim
39 words
A method according to claim 12 wherein the surface holding the photosensitive material is planar, and said shielding from said further radiation is accomplished by positioning said focal volume behind a plane of the surface holding the photosensitive material.
Claim 22
Dependent Claim
51 words
A method according to claim 14 wherein said locating provides for a locating of said focal volume at a distance of approximately one-eighth inch from the side of the object, and said positioning provides for a positioning of said focal volume at a distance of approximately one-eighth inch behind said plane.
Claim 23
Dependent Claim
21 words
A method according to claim 15 wherein said concentrating provides for said focal volume a maximum dimension of approximately 50 microns.
References Cited (Backward Citations)
US2881335A
Cited
US3403252A
Cited
US3210007A
Cited
US3443087A
Cited
US3397631A
Cited
US3512173A
Cited
US3719829A
Cited
US3757491A
Cited
US3923482A
Cited
US3790079A
Cited
US3761941A
Cited
US3914655A
Cited
US4017767A
Cited
US4025790A
Cited
JPS5266884A
Cited
US4199685A
Cited
US4166219A
Cited
US4296322A
Cited
US4365157A
Cited
US4304124A
Cited
US4376637A
Cited
US4383171A
Cited
US4528612A
Cited
US4477263A
Cited
US4602921A
Cited
US4643744A
Cited
US4654183A
Cited
JPS60226130A
Cited
US4716491A
Cited
US4630167A
Cited
US4664938A
Cited
US4635161A
Cited
US4838150A
Cited
US4878149A
Cited
US4746799A
Cited
US4776515A
Cited
US4829398A
Cited
US4809127A
Cited
US4994715A
Cited
US4827371A
Cited
US5114740A
Cited
US5047892A
Cited
US5057966A
Cited
US5175664A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-30 | 1997-11-29 | 1998-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-30 | 2001-11-29 | 2002-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-30 | 2005-11-29 | 2006-05-31 | $7700.00 | Window Closed / Lapsed |