Cleaning system and method

• US 5,770,000 A
• Filed: 05/28/1996
• Issued: 06/23/1998
• Est. Priority Date: 06/11/1995
• Status: Expired due to Fees

• Current Assignee: Sizary-Htp Limited
• Original Assignee: Sizary Materials Purification Limited
• Inventors: Zinman, Iosef, Sergienko, Alex
• Primary Examiner(s): POWELL, WILLIAM A
• Application Number:
  US08/654,031
• Time in Patent Office: 756 Days
• Field of Search: 134/1, 134/1.1, 134/1.2, 134/1.3, 134/694, 438/710, 438/906, 216/67, 216/37, 156/345 P
• US Class Current: 156/345.37
• CPC Class Codes: H01L 21/67028 for cleaning followed by drying, rinsing, stripping, blasting or the like

Abstract

An improved cleaning system is provided for removing impurities from a material to be cleaned. The system includes two electrodes, a positive electrode ("anode") on one side, near to or in contact with the material to be cleaned, and a negative collector electrode ("cathode") located at a distance from the second side of the material. The material and the two electrodes are placed into a chamber. The system also includes a medium of conductivity which, when under voltage between anode and cathode, produces the flow of negative charge either as electrons or as negative ions. The chamber may be a vacuum chamber or a chamber filled with an inert gas or other electro-negative gases. The flow of negative charges provides layer of negative charge near the second surface of the material so as to induce the positive impurity ions to move towards the surface. Since a grid electrode is absent, the impure ions are removed unhindered from the material to be cleaned.

Claims

1. A cleaning system for removing impurities from a material to be cleaned, the system comprising:

a. a first electrode placed near to a first surface of said material to be cleaned;

b. a second electrode placed at a distance from a second surface of said material to be cleaned thereby defining a gap between said second electrode and said material to be cleaned;

c. a chamber into which said first and second electrodes and said material to be cleaned is placed;

d. a medium of conductivity produceable at least within said gap, wherein said first and second electrodes are capable of defining an electrical potential therebetween and inducing, thereby, ion emission from said material to be cleaned to the more negatively charged electrode, and wherein, when said electrical potential exists, said medium of conductivity provides at least a flow of negatively charged particles towards the more positive electrode.

2. A cleaning system according to claim 1 wherein said chamber is a vacuum chamber.

3. A cleaning system according to claim 1 wherein said chamber is filled with a gas wherein said gas is one of the following group:

hydrogen, nitrogen, oxygen, an inert gas, an electro-negative gas and a mixture of any of these gases.

4. A cleaning system according to claim 1 further comprising a heating system for heating at least said material to be cleaned.

5. A cleaning system according to claim 1 and wherein said first electrode is in contact with a first surface of said material to be cleaned.

6. A cleaning system according to claim 1 and wherein said first and second electrode are connected to direct current.

7. A cleaning system according to claim 1 and wherein said first and second electrode are connected to alternating current.

8. A cleaning system according to claim 1 wherein said medium of conductivity is electrons emitted when said second electrode is heated to provide thermoelectric emission.

9. A cleaning system according to claim 1 and also comprising a filament, wherein said medium of conductivity is electrons emitted from said filament when said filament is heated to provide thermoelectric emission.

10. A cleaning system according to claim 1 wherein said medium of conductivity is a plasma formed from a gas.

11. A cleaning system according to claim 1 wherein said medium of conductivity is a plasma formed by means of a high frequency inductor placed external to said chamber.

12. A cleaning system according to claim 10 and wherein said gas is one of the following group:

hydrogen, nitrogen, oxygen, an inert gas, an electro-negative gas and a mixture of any of these gases.

13. A cleaning system according to claim 10 and also comprising a high voltage, high frequency transformer for igniting the gas to produce said plasma.

14. A cleaning system according to claim 13 wherein said transformer is a Tesla transformer.

15. A cleaning system according to claim 10 and also comprising at least a pair of igniter electrodes, for igniting the gas to produce said plasma.

16. A cleaning system according to claim 12 and also comprising at least a pair of igniter electrodes, for igniting the gas to produce said plasma.

17. A cleaning system according to claim 1 and wherein said medium of conductivity produces, in the presence of a voltage potential drop from said first electrode to said second electrode, a negatively charged layer near the second surface of said material to be cleaned thereby producing a potential drop from said first electrode to said negatively charged layer.

18. A cleaning system according to claim 1 and further comprising a third electrode placed at a distance from said first electrode, wherein said first and third electrodes are capable of defining an electrical potential therebetween and inducing, thereby, ion emission from said material to be cleaned to the more negatively charged electrode.

19. A cleaning system according to claim 17 and wherein said electrical potential is produced by means of a transformer.

20. A cleaning system according to claim 18 and wherein said electrical potential is produced by means of a transformer.

21. A cleaning system according to claim 17 and wherein a resistor is connected between said transformer and said first electrode for limiting the flow of electrically charged particles to said first electrode.

22. A cleaning system according to claim 1 and wherein said material to be cleaned is a formed of one of the following group of materials:

semiconductors, conductors and dielectric materials.

23. A cleaning system according to claim 1 and wherein said first electrode is one of the following group of electrodes:

plate, mesh, lattice or ring electrodes.

31. A cleaning system according to claim 1 and wherein said material to be cleaned is formed of semiconductors and conductors.

32. A cleaning system according to claim 1 and wherein said material to be cleaned is formed of conductors and dialectric material.

33. A cleaning system according to claim 1 and wherein said material to be cleaned is formed of semiconductors and dialectric material.

34. A cleaning system according to claim 1 and wherein said material to be cleaned is formed of semiconductors, conductors and dialectric material.

24. A cleaning system for removing impurities from a material to be cleaned, the system comprising:

a. a first electrode at a distance from a first surface of said material to be cleaned thereby defining a first gap between said first electrode and said material to be cleaned;

b. a second electrode placed at a distance from a second surface of said material to be cleaned thereby defining a second gap between said second electrode and said material to be cleaned;

c. a chamber into which said first and second electrodes and said material to be cleaned is placed;

d. a medium of conductivity produceable at least within said gaps;

e. at least one pair of igniter electrodes for igniting the gas to produce said plasma, wherein said first and second electrodes are capable of defining an electrical potential therebetween and inducing, thereby, ion emission from said material to be cleaned to the more negatively charged electrode, and wherein, when said electrical potential is produced by alternating current, said medium of conductivity provides at least a flow of negatively charged particles towards the more positive electrode.

25. A cleaning system according to claim 24 further comprising a heating system for heating at least said material to be cleaned.

26. A system for cleaning and simultaneously oxidizing a surface of a material, the system comprising:

a. a first electrode placed near a first surface of said material;

b. a second electrode placed at a distance from a second surface of said material thereby defining a gap between said second electrode and said material, said second surface being the surface to be oxidized;

c. a chamber into which said first and second electrodes and said material is placed; and

d. a plasma of at least oxygen ions therein and produceable within said chamber, wherein said first and second electrodes are capable of defining an electrical potential therebetween, wherein, when said electrical potential exists, said plasma provides a flow of at least oxygen ions towards said second surface.

27. A cleaning system according to claim 26 and wherein said first electrode is in contact with a first surface of said material to be cleaned.

28. A system according to claim 26 wherein said first and second electrodes are non-oxidizable electrodes.

29. A system according to claim 26 wherein said chamber is a vacuum chamber.

30. A system according to claim 26 wherein said chamber is filled with a gas wherein said gas is one of the following group:

hydrogen, nitrogen, oxygen, an inert gas, an electro-negative gas and a mixture of any of these gases.