Abrading – Abrading process – With tool treating or forming
Reexamination Certificate
2000-07-10
2001-12-11
Banks, Derris H. (Department: 3723)
Abrading
Abrading process
With tool treating or forming
C451S443000, C451S444000
Reexamination Certificate
active
06328637
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for conditioning a polishing pad. More particularly, the present invention relates to a method and apparatus for conditioning a polishing pad used in the chemical mechanical planarization of semiconductor wafers.
BACKGROUND OF THE INVENTION
Semiconductor wafers are typically fabricated with multiple copies of a desired integrated circuit design that will later be separated and made into individual chips. A common technique for forming the circuitry on a semiconductor is photolithography. Part of the photolithography process requires that a special camera focus on the wafer to project an image of the circuit on the wafer. The ability of the camera to focus on the surface of the wafer is often adversely affected by inconsistencies or unevenness in the wafer surface. This sensitivity is accentuated with the current drive toward smaller, more highly integrated circuit designs. Semiconductor wafers are also commonly constructed in layers, where a portion of a circuit is created on a first level and conductive vias are made to connect up to the next level of the circuit. After each layer of the circuit is etched on the wafer, an oxide layer is put down allowing the vias to pass through but covering the rest of the previous circuit level. Each layer of the circuit can create or add unevenness to the wafer that is preferably smoothed out before generating the next circuit layer.
Chemical mechanical planarization (CMP) techniques are used to planarize the raw wafer and each layer of material added thereafter. Available CMP systems, commonly called wafer polishers, often use a rotating wafer holder that brings the wafer into contact with a polishing pad moving in the plane of the wafer surface to be planarized. A polishing fluid, such as a chemical polishing agent or slurry containing microabrasives, is applied to the polishing pad to polish the wafer. The wafer holder then presses the wafer against the rotating polishing pad and is rotated to polish and planarize the wafer.
With use, the polishing pads used on the wafer polishers become clogged with used slurry and debris from the polishing process. The accumulation of debris reduces the surface roughness and adversely affects polishing rate and uniformity. Polishing pads are typically conditioned to roughen the pad surface, provide microchannels for slurry transport, and remove debris or byproducts generated during the CMP process.
One present method for conditioning a polishing pad uses a rotary disk embedded with diamond particles to roughen the surface of the polishing pad. Typically, the disk is brought against the polishing pad and rotated about an axis perpendicular to the polishing pad while the polishing pad is rotated. The diamond coated disks produce predetermined microgrooves on the surface of the polishing pad. Because the linear velocities of the leading, center and lagging portions of the disk are different, the rate of microgrooving is different. This non-uniform microgrooving has led some pad conditioner manufacturers to add a continuous oscillation motion to the rotational movement of the rotary disk pad conditioners. This extra movement can result in part of the wafer being exposed to freshly conditioned portions of the polishing pad and another part of the wafer being exposed to a used portion of the pad.
Another apparatus and method used for conditioning a pad implements a rotatable bar on the end of an arm. The bar may have diamond grit embedded in it or high pressure nozzles disposed along its length. In operation, the arm swings the bar out over the rotating polishing pad and the bar is rotated about an axis perpendicular to the polishing pad in order to score the polishing pad, or spray pressurized water on the polishing pad, in a concentric pattern. These types of pad conditioners often do not provide uniform pad conditioning because they are only applied to a small portion of the width of the pad's surface at any given time. Thus, the pressure of the conditioner against the pad can vary.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a pad conditioning apparatus is provided having an elongated pad conditioning member rotatably positioned around a shaft, where the shaft has an axis substantially parallel to the plane of the polishing pad. An abrasive substance is disposed along at least a portion of the exterior circumference of the elongated pad conditioning member. A pressure application system is connected to the shaft and configured to removably press the elongated pad conditioning member against the polishing pad. Also, a motor is connected to the elongated pad conditioning member and is configured to rotationally reciprocate the exterior circumference of the elongated pad conditioning member about the shaft while the pressure application system presses the elongated pad conditioning member against the polishing pad. In one embodiment, the elongated pad conditioning member is a cylindrical roller
According to a second aspect of the present invention, a polishing pad conditioner includes a roller having a first end and a second end where the axis of rotation of the roller is oriented substantially parallel to a polishing plane of the polishing pad. An abrasive substance is affixed to the roller on at least a portion of the outer circumference of the roller. A pressure control system connects to at least one of the first and second ends of the roller so that the pressure control system can maintain a desired pressure of the roller against the polishing pad when conditioning the polishing pad.
In another aspect, a pad conditioner for conditioning a polishing pad on a linear wafer polishing device used in chemical mechanical planarization of semiconductor wafers is disclosed. A cylindrical roller is rotatably connected to a bracket, where the cylindrical roller has an axial length at least as great as the width of the polishing pad. An abrasive substance is embedded in at least a portion of an outer circumference of the roller and a pressure application device is attached to the bracket. The pressure application device is movably adjustable in a direction perpendicular to the rotational axis of the roller.
According to another aspect of the present invention, a method of conditioning a polishing pad includes the steps of providing a polishing pad conditioner having a cylindrical roller with a longitudinal rotational axis, positioning the polishing pad conditioner adjacent the polishing pad so that the longitudinal rotational axis of the roller is oriented substantially parallel to the polishing pad, and moving the roller against the polishing pad while the polishing pad is moving. A pressure is maintained against the polishing pad with the cylindrical roller. In one embodiment, the roller is rotationally reciprocated about the longitudinal axis by a motor. In another embodiment, the roller is passively rotatable and driven by contact with the polishing pad.
REFERENCES:
patent: 3753269 (1973-08-01), Budman
patent: 4318250 (1982-03-01), Klievoneit et al.
patent: 4672985 (1987-06-01), Mohr
patent: 4720939 (1988-01-01), Simpson et al.
patent: 4934102 (1990-06-01), Leach et al.
patent: 5081051 (1992-01-01), Mattingly et al.
patent: 5335453 (1994-08-01), Baldy et al.
patent: 5484323 (1996-01-01), Smith
patent: 5531635 (1996-07-01), Mogi et al.
patent: 5536202 (1996-07-01), Appel et al.
patent: 5547417 (1996-08-01), Breivogel et al.
patent: 5575707 (1996-11-01), Talieh et al.
patent: 5593344 (1997-01-01), Weldon et al.
patent: 5611943 (1997-03-01), Cadien et al.
patent: 5622526 (1997-04-01), Phillips
patent: 5643044 (1997-07-01), Lund
patent: 5655951 (1997-08-01), Meikle et al.
patent: 5692947 (1997-12-01), Talieh et al.
patent: 5725417 (1998-03-01), Robinson
patent: 5759918 (1998-06-01), Hoshizaki et al.
patent: 5779526 (1998-07-01), Gill
patent: 5871390 (1999-02-01), Pant et al.
patent: 5897426 (1999-04-01), Somekh
patent: 5899798 (1999-05-01), Trojan et al.
patent: 6086460 (2000-07-01), Labunsky
Huynh Tac
Labunsky Michael
Meyer Anthony
Nagengast Andrew
Travis Glenn W.
Banks Derris H.
Brinks Hofer Gilson & Lione
Lam Research Corporation
LandOfFree
Method and apparatus for conditioning a polishing pad used... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for conditioning a polishing pad used..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for conditioning a polishing pad used... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2561295