Patent Grant
7059939
The invention relates to a chemical mechanical polishing (CMP) apparatus, and more particularly to a chemical mechanical polishing apparatus with a polishing pad conditioner and a real-time monitoring method therefor.
The manufacture of integrated circuit devices requires the formation of various layers, such as conductor, semiconductor, and insulator layers, on a substrate to form necessary components and interconnects. During the manufacturing process, removal of specific layers or portions thereof must be achieved in order to planarize the various components and interconnects. Chemical mechanical polishing (CMP) is extensively pursued to planarize a surface of a semiconductor substrate, such as a silicon substrate, at various stages of integrated circuit processing. It is also used in polishing optical surfaces, metrology samples, micro-machinery, and various metal and semiconductor based substrates.
The polishing pad of the CMP apparatus requires a uniform and flat surface to provide a desired polishing rate. Over time, however, the polishing process glazes the polishing pad and creates irregularities therein. Accordingly, the polishing pad surface is typically deglazed by a polishing pad conditioner, whereby slurry trapped in the pad pores and surface irregularities is removed and the polishing pad is roughened such that slurry is capable of spreading uniformly thereon.
U.S. Pat. No. 6,699,107, the entirety of which is hereby incorporated by reference, discloses a chemical mechanical polishing apparatus with a polishing pad conditioner.
A similar conditioner apparatus is disclosed in U.S. Pat. No. 6,695,680 the entirety of which is incorporated herein by reference. The polishing pad conditioner typically comprises a conditioning head having a diamond disk with a roughened surface, a rotary actuating device rotating the conditioning head, and a linear actuating device driving the conditioning head up and down. The conditioning head is moved onto the polishing pad, and the conditioning head rotated against the polishing pad while being forced downward by the actuating devices, thereby conditioning the polishing pad.
It is very important for a CMP apparatus to provide a smooth and controllable polishing rate. In any case, pad conditioning cannot be performed uniformly when the shaft of the conditioner head is jammed by slurry residue or a sealing o-ring is worn. The downward force of the conditioning head is an important processing factor. If downward force of the conditioner head is uneven and unstable, difficulty in controlling thickness and range of the polished layer can result. Unfortunately, instability of thickness of the polished layer caused by the shaft of the conditioning head is detected only after several wafer lots have been polished, thereby decreasing production yield. Moreover, real-time downward force is always not easy to detect, with the sole warning system being thickness of the oxide layer measured after CMP. More specifically, a typical CMP system only maintains the polishing rate in either ex-situ or non-real-time-in-situ pad conditioning, that is, the step of monitoring polishing pad conditioner cannot be simultaneously implemented during CMP.
Accordingly, the invention provides a chemical mechanical polishing apparatus and a real-time monitoring method therefore with downward force thereof transformed using sensors.
Further provided is a method of monitoring downward force of the conditioning head in real time at a real location during CMP.
A polishing pad conditioner for a chemical mechanical polishing apparatus comprises a transverse beam, a conditioning head comprising an abrasive disk for conditioning a polishing pad, with the conditioning head supported for rotation at one end of the transverse beam, a drive assembly coupled to the conditioning head providing downward force to the conditioning head, and at least one sensor disposed on the transverse beam to detect deflection of the transverse beam.
Also provided is a method of monitoring a polishing pad conditioner, comprising moving a conditioning head in contact with a polishing pad, producing downward force to the conditioning head against the polishing pad, while sensing deflection of a transverse beam, and comparing the value of the deflection of the transverse beam with a corresponding value representative of a normal operation of the polishing pad conditioner.
The invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein:
A gear box 216 (not shown) is provided over the rotating motor 213 and the swing motor 214 to transmit driving forces supplied by motors 213 and 214. A first pulley 220 rotated by a rotating motor 213 and an air pressure controller 230 are disposed in an upper part of the first end of the housing 210. A second pulley 250 is disposed in the second end of the housing 210. A timing belt 240 engages the first pulley 220 and the second pulley 250, so that the timing belt 240 is driven in association with the rotation of the first pulley 220 to transfer rotary drive force to the second pulley 250.
An air supply tube 232 and an air recovery tube 231 are connected to the air pressure controller 230 and extend longitudinally along the upper part of the housing 210 between the first and second ends thereof. Furthermore, the air supply tube 232 extends into a hole formed through the second end of the housing 210 at the center portion thereof.
A conditioning head 260 having a diamond abrasive disk is mounted on the bottom of the second end of the housing 210 and is rotatably connected thereto by means of a shaft.
The transverse beam bears only the load of the conditioning head F, for example, 5–11 lb. The upper surface 410a′ of the transverse beam 410 is tensile, while the lower surface 410b′ of the transverse beam 410 is compressed. As downward force is provided to the conditioning head 430, a counter force Fd is exerted against the conditioning head 430. The upper surface 410a′ of the transverse beam 430 can be compressed, while the lower surface 410b′ of the transverse beam 410 can be tensile, as shown in
Deflection of the transverse beam is measured by at least one sensor, preferably a strain gauge. Alternatively, deflection of the transverse beam can also be measured by an optical device, such as photodetector.
The value of the deformation of the transverse beam 420 is compared with a predetermined deformation value (S30) using a comparison circuit unit 480. Where differences occur, the CMP apparatus is inter-locked (S50) and the CMP process stopped by the presence of abnormal operation, whereby appropriate actions are taken to obviate the problem or problems causing the abnormal operation.
Abnormality detection indicates that the shaft of the conditioner head is jammed by slurry and/or the O-ring is worn out or torn. In fact, most cases of abnormal operation due to low or unstable down force are the result of a jammed shaft. In this case, primary maintenance and cleaning of the shaft of the conditioner head are required.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5975994 | Sandhu et al. | Nov 1999 | A |
| 6146241 | Lee et al. | Nov 2000 | A |
| 6306008 | Moore | Oct 2001 | B1 |
| 6524959 | Lu et al. | Feb 2003 | B1 |
| 6695680 | Choi et al. | Feb 2004 | B1 |
| 6699107 | Marxsen et al. | Mar 2004 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20060046619 A1 | Mar 2006 | US |
