US4178188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for cleaning workpieces by ultrasonic energy
Assignee: Branson Ultrasonics Corp
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Filing: 1978-08-07
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Granted: 1979-12-11
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Expires: 1998-08-07
Abstract
Abstract A delicate workpiece, such as a semiconductor wafer is cleaned by supporting the workpiece on a shaft which is rotated. A film of liquid solvent is caused to continuously flow across the exposed workpiece surface while the workpiece is in rotation and ultrasonic energy is applied to the liquid film for causing cavitation in the solvent, thereby effecting cleaning of the workpiece surface. Upon shutting off the solvent and the ultrasonic energy, the workpiece is dried by spinning it at high speed.
Inventors
- 👤 Jean G. M. Dussault
- 👤 Robert A. Geckle
- 👤 William L. Puskas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:52
CPC Classifications
B; B08; B08B; B08B3/00; B08B3/04; B08B3/10; B08B3/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
161 words
The method of cleaning a workpiece comprising the steps of: disposing a workpiece on a support in a manner for providing an exposed side of the workpiece; rotating said support to cause the workpiece to undergo rotation about an axis intersecting said exposed side at a substantially perpendicular angle; disposing an electroacoustic transducer spaced from the exposed side of the workpiece to form a gap between the transducer and the exposed side; flooding the exposed side of the workpiece with a film of solvent flowing across the exposed side through the gap between the transducer and the exposed side; applying ultrasonic energy emitted by the transducer to the flowing film of solvent to cause cavitation therein for effecting cleaning of the exposed side of the workpiece while the workpiece undergoes rotation; ceasing flooding of the exposed side of the workpiece, and subsequently rotating the support at a rotational speed sufficient to effect solvent removal from the exposed side by centrifugal force.
Claim 2
Independent Claim
161 words
The method of cleaning a workpiece comprising the steps of: disposing a workpiece on a support in a manner for providing an exposed side of the workpiece; rotating said support to cause the workpiece to undergo rotation about an axis intersecting said exposed side at a substantially perpendicular angle; disposing an electroacoustic transducer spaced from the exposed side of the workpiece to form a gap between the transducer and the exposed side; flooding the exposed side of the workpiece with a film of solvent flowing across the exposed side through the gap between the transducer and the exposed side; applying ultrasonic energy emitted by the transducer to the flowing film of solvent to cause cavitation therein for effecting cleaning of the exposed side of the workpiece while the workpiece undergoes rotation; ceasing flooding of the exposed side of the workpiece, and subsequently rotating the support at a rotational speed sufficient to effect solvent removal from the exposed side by centrifugal force.
Claim 3
Dependent Claim
26 words
The method of cleaning as set forth in claim 1, and removing the workpiece from said support after removal of the solvent from the cleaned workpiece.
Claim 4
Dependent Claim
18 words
The method of cleaning as set forth in claim 1, the workpiece being a flat wafer type article.
Claim 5
Dependent Claim
16 words
The method of cleaning as set forth in claim 3, said wafer being a semiconductor material.
Claim 6
Dependent Claim
22 words
The method of cleaning as set forth in claim 1, the workpiece being disposed on said support in a substantially horizontal plane.
Claim 7
Dependent Claim
27 words
The method of cleaning as set forth in claim 1, the ultrasonic energy being selected to have a frequency in range from 20 kHz to 100 kHz.
Claim 8
Dependent Claim
16 words
The method of cleaning as set forth in claim 1, the solvent being an aqueous solution.
Claim 9
Dependent Claim
20 words
The method of cleaning as set forth in claim 1, said film of solvent being less than 6 mm thick.
Claim 10
Dependent Claim
29 words
The method of cleaning as set forth in claim 1, rotating the workpiece at a first speed during cleaning and at a second speed for effecting the solvent removal.
Claim 11
Dependent Claim
19 words
The method of cleaning as set forth in claim 9, said second speed being higher than said first speed.
Claim 12
Dependent Claim
21 words
The method of cleaning as set forth in claim 1, said electroacoustic transducer being disposed stationary relative to the rotating workpiece.
References Cited (Backward Citations)
US2828231A
Cited
US2980123A
Cited
US3577278A
Cited
US3829328A
Cited
US3849195A
Cited
US4027686A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |