US5897379A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low temperature system and method for CVD copper removal
Assignee: Sharp Corp
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Filing: 1997-12-19
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Granted: 1999-04-27
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Expires: 2017-12-19
Abstract
Abstract A method of using diluted nitric acid and an edge bead removal tool to remove copper from the perimeter of a semiconductor wafer is provided. In one embodiment, sensitive areas of the wafer are covered with photoresist, and the wafer perimeter cleared of photoresist, before the acid is applied. In another embodiment, sensitive areas of the wafer are protected with water spray as the copper etchant is applied. In a third embodiment, the nitric acid is applied to clear the wafer perimeter of copper before a chemical mechanical polishing (CMP) is performed on the layer of deposited copper. The excess thickness of copper protects copper interconnection structures from reacting with the copper etchant. All these methods permit copper to be removed at a low enough temperature that copper oxides are not formed. A semiconductor wafer cleaned of copper in accordance with the above-described method, and a system for low temperature copper removal is also provided.
Inventors
- 👤 Bruce Dale Ulrich
- 👤 Tue Nguyen
- 👤 Masato Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:30
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/66; H10P50/663; H10P50/667; C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/18; H10P52/00; H10P52/40; H10P52/403; H10P70/00; H10P70/20; H10P70/23; H10P70/234; H10P70/50; H10P70/54; H10P72/00; H10P72/04; H10P72/0402; H10P72/0418; H10P72/0422; H10P72/0424
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
87 words
In the fabrication of a semiconductor wafer having top and bottom surfaces, with a top surface edge and a side along the top surface edge around the perimeter of the wafer surfaces, a low temperature method for removing copper from the wafer, the method comprising the steps of: a) forming a layer of protective coating overlying selected areas the wafer top surface; and b) applying a diluted copper etchant solution at room temperature to remove copper from portions of the wafer not covered by the protective coating.
Claim 2
Dependent Claim
87 words
In the fabrication of a semiconductor wafer having top and bottom surfaces, with a top surface edge and a side along the top surface edge around the perimeter of the wafer surfaces, a low temperature method for removing copper from the wafer, the method comprising the steps of: a) forming a layer of protective coating overlying selected areas the wafer top surface; and b) applying a diluted copper etchant solution at room temperature to remove copper from portions of the wafer not covered by the protective coating.
Claim 3
Dependent Claim
65 words
A method as in claim 1 wherein the wafer top surface selective areas includes copper interconnects, and in which Step a) includes depositing the protective coating upon the wafer top surface, including the non-selected areas, and etching the protective coating to remove the protective coating from the edges of the top surface and sides of the wafer, but not from the top surface copper interconnects.
Claim 4
Dependent Claim
31 words
A method as in claim 1 in which Step a) includes a protective coating selected from the group consisting of photoresist, photoresist without photo active compound (PAC), and spin-on glass (SOG).
Claim 5
Dependent Claim
96 words
A method as in claim 3 wherein the wafer includes at least one straight top surface edge and side, in which Step a) includes depositing photoresist on the wafer top surface, exposing selected areas of the photoresist along the straight top surface edge to light through a shadow-mask in close proximity to the wafer, to chemically alter the exposed photoresist, and in which Step a) includes developing the photoresist to remove photoresist along the straight edge of the top surface, whereby copper is etched from the top surface straight edge in subsequent steps of the method.
Claim 6
Dependent Claim
48 words
A method as in claim 3 in which Step a) includes forming a protective coating with photoresist, and further comprising the step, following Step a), and preceding Step b), of: soft-baking the photoresist at a temperature of 95° C., or less, for a period of approximately 60 seconds.
Claim 7
Dependent Claim
53 words
A method as in claim 1 comprising the steps, following Step b), of: c) cleaning the wafer of copper etchant compounds with a de-ionized water rinse; and d) etching the protective coating to completely remove protective coating from the wafer, whereby the wafer, free of copper contaminants, is available for further semiconductor processes.
Claim 8
Dependent Claim
33 words
A method as in claim 1 comprising the following step, before Step a), of: performing a chemical mechanical polish (CMP) to remove excess copper from the circuit areas of the wafer top surface.
Claim 9
Dependent Claim
37 words
A method as in claim 1 in which Step b) includes using nitric acid as the copper etchant, having a concentration of less than approximately 30%, whereby the copper is removed at low temperatures to minimize oxidation.
Claim 10
Dependent Claim
122 words
In the fabrication of a semiconductor wafer disk having top and bottom surfaces, with a top surface edge and a side along the top surface edge around the perimeter of the wafer surfaces, a low temperature method for removing copper from the wafer using a spin-etch processor chamber including a spin chuck and at least a first solution application nozzle, the method comprising the steps of: a) rotating the wafer at room temperature, at a first revolution per minute (RPM) rate; b) locating the first nozzle above the top surface edge; and c) applying a diluted copper etchant with the first nozzle to the top surface edge, whereby copper is removed from the exposed edges of the top surface and wafer sides.
Claim 11
Dependent Claim
122 words
In the fabrication of a semiconductor wafer disk having top and bottom surfaces, with a top surface edge and a side along the top surface edge around the perimeter of the wafer surfaces, a low temperature method for removing copper from the wafer using a spin-etch processor chamber including a spin chuck and at least a first solution application nozzle, the method comprising the steps of: a) rotating the wafer at room temperature, at a first revolution per minute (RPM) rate; b) locating the first nozzle above the top surface edge; and c) applying a diluted copper etchant with the first nozzle to the top surface edge, whereby copper is removed from the exposed edges of the top surface and wafer sides.
Claim 12
Dependent Claim
86 words
A method as in claim 9 further wherein a layer of copper having a first thickness overlies the wafer top surface edge and a second thickness overlies copper interconnects, in which Step c) includes removing the first thickness of copper overlying the top surface edge and sides, and further comprising a step, following Step c), of: d) performing a CMP to remove the second thickness of copper overlying the interconnects, revealing the copper interconnect structures, whereby copper is removed without the use of a protective coating.
Claim 13
Dependent Claim
83 words
A method as in claim 9 wherein a second solution application nozzle is provided, and further comprises the steps, preceding Step a), of: depositing a protective coating, selective to the copper etchant used in Step c), on the top surface of the wafer; rotating the wafer and locating the second nozzle above the edge of the top surface; and applying a protective coating etchant with the second nozzle to remove the protective coating along the top surface edge and sides of the wafer.
Claim 14
Dependent Claim
33 words
A method as in claim 11 in which Step a 1 ) includes a protective coating selected from the group consisting of photoresist, photoresist without photo active compound (PAC), and spin-on glass (SOG).
Claim 15
Dependent Claim
52 words
A method as in claim 12 in which the step of depositing a protective coating on the top surface of the wafer includes using photoresist as the protective coating, and in which the wafer is baked at a temperature of 95° C., or less, for a period of 60 seconds, or less.
Claim 16
Dependent Claim
50 words
A method as in claim 13 wherein the second nozzle is moveable, and including the further step, following Step c), of: e) moving the second nozzle from the center of the wafer to the top surface edge, applying photoresist etchant to the entire top surface, to completely removing the photoresist.
Claim 17
Dependent Claim
29 words
A method as in claim 9 in which Step c) includes using a solution of nitric acid as the copper etchant, having a concentration of less than approximately 30%.
Claim 18
Dependent Claim
24 words
A method as in claim 15 in which Step c) includes the rate of rotation being in the range between 250 and 1000 RPM.
Claim 19
Dependent Claim
49 words
A method as in claim 16 including a further step, following Step c), and preceding Step e), of: allowing the rotating wafer to come to rest for a period of approximately 15 seconds while still covered with the copper etchant solution, whereby the use of copper etchant is conserved.
Claim 20
Dependent Claim
31 words
A method as in claim 17 in which the method cycles between Step c) and the step of allowing the rotating wafer to come to a rest a plurality of times.
Claim 21
Dependent Claim
95 words
A method as in claim 18 wherein a third solution application nozzle is provided, and further comprising a step, following the step of allowing the rotating wafer to come to a rest, of: rotating the wafer and applying de-ionized water with the third nozzle to the wafer top surface, removing copper etchant and copper etchant by-products from the wafer; and in which the method cycles between Step c), the step of allowing the rotating wafer to come to a rest, and the step of rotating the wafer to apply de-ionized water a plurality of times.
Claim 22
Dependent Claim
80 words
A method as in claim 9 wherein a third solution application nozzle is provided, and further comprising a step, following Step b) and simultaneously with Step c), of: locating the third nozzle at approximately the center of the wafer, and applying de-ionized water with the third nozzle to the wafer top surface, removing copper etchant and copper etchant by-products from the wafer, whereby the de-ionized water protects copper structures on the wafer top surface from damage from the copper etchant.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-04-26 | 2002-10-26 | 2003-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-04-26 | 2006-10-26 | 2007-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-04-26 | 2010-10-26 | 2011-04-27 | $7700.00 | Window Closed / Lapsed |