Abrading – Accessory – Tool cleaner
Reexamination Certificate
1998-11-02
2001-04-17
Banks, Derris H. (Department: 3723)
Abrading
Accessory
Tool cleaner
C451S442000
Reexamination Certificate
active
06217430
ABSTRACT:
BACKGROUND
The present invention relates generally to chemical mechanical polishing of substrates and, more particularly to a polishing pad conditioner cleaning apparatus.
Integrated circuits are typically formed on substrates, particularly silicon wafers, by the sequential deposition of conductive, semiconductive or insulative layers. Specific structures and devices are formed by preferential etching of the layers aided by photolithography. High resolution and accurate focusing of the photolithography apparatus allows the formation of well defined micro- or nano-structures. Accurate focusing of the photolithography apparatus is difficult for non-planar surfaces. Therefore, there is a need to periodically planarize the substrate surface to provide a planar surface. Planarization, in effect, polishes away a non-planar, outer surface, whether a conductive, semiconductive, or insulative layer, to form a relatively flat, smooth surface.
Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier or polishing head, with the surface of the substrate to be polished exposed. The substrate is then placed against a rotating polishing pad. The carrier head provides a controllable load, i.e., pressure, on the substrate to push it against the polishing pad. In addition, the carrier head may rotate to provide additional motion between the substrate and polishing surface. Further, a polishing slurry, including an abrasive and at least one chemically-reactive agent, may be spread on the polishing pad to provide an abrasive chemical solution at the interface between the pad and substrate.
The effectiveness of a CMP process may be measured by its polishing rate, and by the resulting finish (absence of small-scale roughness) and flatness (absence of large-scale topography) of the substrate surface. Inadequate flatness and finish can produce substrate defects. The polishing rate, finish and flatness are determined by the pad and slurry combination, the relative speed between the substrate and pad, and the force pressing the substrate against the pad. The polishing rate sets the time needed to polish a layer. Thus, it sets the maximum throughput of the polishing apparatus.
It is important to take appropriate steps to counteract any deteriorative factors which may either damage the substrate (such as by scratches resulting from accumulated debris in the pad) or reduce polishing speed and efficiency (such as results from glazing of the pad surface after extensive use). The problems associated with scratching the substrate surface are self-evident. The more general pad deterioration problems both decrease polishing efficiency, which increase cost, and create difficulties in maintaining consistent operation from substrate to substrate as the pad decays.
The glazing phenomenon is a complex combination of contamination, thermal, chemical and mechanical damage to the pad material. When the polisher is in operation, the pad is subject to compression, shear and friction producing heat and wear. Slurry and abraded material from the wafer and pad are pressed into the pores of the pad material and the material itself becomes matted and even partially fused. These effects reduce the pad's roughness and its ability to efficiently polish the substrate.
It is, therefore, desirable to continually condition the pad by removing trapped slurry, and unmatting or re-expanding the pad material.
A number of conditioning procedures and apparatus have been developed. A conventional conditioner has an arm holding a conditioner head with an abrasive disk facing the polishing pad. A bearing system rotatably supports the abrasive disk at the end of the arm. The abrasive disk rotates against the polishing pad to physically abrade the polishing pad and remove the glazing layer from the polishing pad.
While the abrasive disk is rotating against the polishing pad, slurry will tend to coat the conditioner head. However, when the conditioner head is not operating, e.g., between polishing operations or due to maintenance, the slurry on conditioner head will tend to dry out. As the slurry dries, it tends to form a hardened “caked” surface, and sodium hydroxide in the slurry tends to crystallize. The resulting solidified slurry particles may fall off the conditioner head onto the polishing pad. These particles may scratch the wafer during polishing. The CMP apparatus can include a cleaning cup for removing slurry deposits from a conditioner head. Unfortunately, some wafer scratching persists.
The slurry solidification problem has been associated generally with the abrasive disk of the conditioner head since it is the part of the conditioner head that physically contacts the polishing pad. In reality, the slurry may be splashed on other parts of the conditioner head, e.g., a top side of the conditioner head.
In view of the above, there is room for improvement in cleaning of the conditioner head.
SUMMARY
In general, in one aspect, the present invention features a chemical mechanical polishing apparatus comprising a pad conditioner and a cleaning cup having a base and walls extending upward from the base for holding and cleaning the conditioner head. The cleaning cup includes a spray nozzle for spraying cleaning solution onto the conditioner head.
Implementations of the invention may include one or more of the following features. The cleaning cup further includes a first passage for directing the cleaning solution to the spray nozzle. The cleaning cup further includes a spray nozzle support having a second passage, the spray nozzle support supporting the spray nozzle and connecting the first and second passages to direct the cleaning solution to the spray nozzle. The cleaning cup further includes a cleaning solution passage for continuously supplying the cleaning solution to the cleaning cup. The cleaning cup further includes a continuous cleaning solution passage for continuously supplying the cleaning cup with a cleaning solution. The cleaning cup further includes at least one drain to drain the cleaning solution from the cleaning cup. The cleaning solution in the cleaning cup is maintained at a substantially constant level. The cleaning solution is deionized water. The cleaning cup includes a plurality of spray nozzles. The spray nozzle sprays a cleaning solution on a top side of the conditioner head.
In another embodiment, the invention is a method of cleaning a chemical mechanical polishing apparatus. The method comprises placing a pad conditioner including a conditioner head in a cleaning cup; and turning on a cleaning solution dispenser to provide a cleaning solution to a top side of the conditioner head.
The invention provides a cleaning apparatus which can clean the entire conditioner head. The invention also provides a reliable means of cleaning an abrasive disk without undue risk of contaminating the abrasive disk.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments, and from the claims.
REFERENCES:
patent: 5081051 (1992-01-01), Mattingly et al.
patent: 5216843 (1993-06-01), Breivogel et al.
patent: 5456627 (1995-10-01), Jackson et al.
patent: 5486131 (1996-01-01), Cesna et al.
patent: 5531635 (1996-07-01), Mogi et al.
patent: 5626509 (1997-05-01), Hayashi
patent: 5738574 (1998-04-01), Tolles et al.
patent: 5804507 (1998-09-01), Perlov et al.
patent: 5839947 (1998-11-01), Kimura et al.
patent: WO 99/02305 (1999-01-01), None
Brown Brian J.
Fishkin Boris
Hoey Gee
Koga Raijiro
Kumagai Takashi
Applied Materials Inc.
Banks Derris H.
Fish & Richardson
LandOfFree
Pad conditioner cleaning apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pad conditioner cleaning apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pad conditioner cleaning apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2518517