JP2005081461A - Polishing method and device of wafer or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method of a wafer and a polishing device therefor, easily monitoring at any time without any increase in the load of a device body control part. <P>SOLUTION: In this polishing method, a material to be polished is polished by a polishing pad and the polishing pad is dressed by a dresser alternately. In the polishing method and the polishing device, a polishing pad replacement threshold is set, the abrasion amount of the polishing pad is measured on the basis of the travel of the dresser, and the measurement result and the polishing pad replacement threshold are compared with each other to determine the replacement time of the polishing pad. Further, after the polishing pad is replaced, the polishing pad replacement threshold is reset, and the replacement time of the replaced polishing pad is determined. A material to be polished is preferably a silicon wafer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polishing method for determining a wear amount of a grinding surface of a polishing pad for polishing and flattening a surface of a semiconductor wafer or the like, and to replace a polishing pad having a use limit at an appropriate time, and a polishing method thereof Relates to the device.

  Polishing of a semiconductor wafer or the like by a polishing apparatus is performed by rotating a polishing platen having a polishing pad fixed on the upper surface and fixing the wafer to a wafer holder provided facing the polishing pad. While a polishing liquid containing abrasive grains was dropped onto the wafer, the wafer was pressed against the polishing pad with a predetermined pressing force and polished, and the surface of the polishing pad was dressed using a dressing device before polishing.

  Since the polishing pad wears during use, it is necessary to constantly monitor whether the amount of wear exceeds a certain value by measuring the amount of wear, and the amount of wear on the polishing pad is not measured at the center of the pad. The level difference between the polished part and the polished part was measured with a depth gauge. Therefore, it is necessary to stop the apparatus for measurement, the measurement frequency is limited, and the foreign matter on the pad surface increases because the gauge is brought into contact with the pad.

In order to solve the above problem, a method of sampling and measuring the polishing pad height relative to the data base during wafer polishing and determining the polishing pad replacement time has been proposed. However, there is a demerit that it may not be possible to measure with high accuracy because it is affected by variations in wafer thickness due to differences in processing processes.
In addition, it is necessary to accumulate the data for calculating the wear amount of the polishing pad and store the estimated value of the wear amount of the polishing pad obtained from the accumulated data. There is a problem that the load on the computer is large (Patent Document 1).

JP-A-9-290363

Therefore, the present invention can measure the wear amount of the polishing pad in real time and without being affected by the wafer thickness due to the difference in the type of wafer or the processing process without interrupting the polishing operation, and the measurement result It is an object to provide a polishing method for a wafer or the like and an apparatus for polishing the same that output an alarm when reaching a preset limit wear amount of the polishing pad.
It is another object of the present invention to provide a wafer polishing method and a polishing apparatus thereof that can be always and easily monitored without increasing the load on the apparatus main body control unit.

  In order to solve the above-mentioned problems, the invention of claim 1 sets a polishing pad replacement threshold in a polishing method in which polishing an object to be polished with a polishing pad and dressing the polishing pad with a dresser alternately, The invention according to claim 2, wherein the wear amount of the polishing pad is measured based on the amount of movement of the dresser, and the polishing pad replacement time is determined by comparing the measurement result with the polishing pad replacement threshold. Further, in the invention of claim 1, the polishing pad replacement threshold is reset after the polishing pad replacement, and the replacement timing of the polishing pad after the replacement is determined. In the invention of 2, the object to be polished is a silicon wafer.

  Similarly, the invention of claim 4 is a polishing surface plate to which a polishing object holder for holding a polishing object and a polishing pad for polishing the polishing object held by the polishing object holder are attached. And a polishing device having a dresser for dressing the polishing pad and a device control unit, and a function of measuring the movement amount of the dresser and determining whether or not the polishing pad needs to be replaced based on the measurement result. The invention of claim 5 is characterized in that, in the invention of claim 4, the measurement result of the movement amount of the dresser is compared with a preset polishing pad replacement threshold value, and the measurement result exceeds the threshold value. The invention of claim 5 has a function of notifying a replacement instruction of the polishing pad. In the invention of claim 4, the measurement result of the movement amount of the dresser and a preset polishing pad are provided. The present invention has a function of notifying a pad replacement instruction when the measured result exceeds the threshold, and the invention according to claim 6 is the polishing pad replacement according to the invention of claim 5. It has a function of resetting the polishing pad replacement threshold later.

According to a seventh aspect of the present invention, in any of the fourth to sixth aspects of the present invention, the polishing pad replacement timing control unit determines whether or not the polishing pad needs to be replaced based on a measurement result of the movement amount of the dresser. It is characterized by that.
In this way, a “polishing pad replacement time control unit” is provided separately from the device main body control unit, and only main signals such as an alarm for replacement time are transmitted to the device main body control unit, thereby increasing the load on the device main body control unit. It is easy to constantly monitor.

  Furthermore, an invention of claim 8 is the invention according to any one of claims 4 to 7, wherein the object to be polished is a silicon wafer.

  The method for polishing a wafer or the like and the polishing apparatus thereof according to the present invention determine the amount of wear of the polishing pad by measuring the amount of movement of the dresser with a laser displacement meter, so that the amount of wear of the polishing pad can be measured in real time. In addition, since the wear amount of the polishing pad is not measured via a wafer or the like, it can always be accurately measured without being affected by the wafer thickness due to the difference in the type of wafer or the like and the processing process.

  In addition, since the measuring instrument is not in contact with the polishing pad, foreign matter on the surface of the polishing pad can be reduced.

  In addition, the wafer polishing method and polishing apparatus of the present invention are provided with a “replacement timing control unit” separately from the apparatus main body control unit, thereby enabling easy and constant monitoring of the wafer and its polishing method. An apparatus can be provided.

FIG. 1 is a flowchart of a wafer polishing method according to the present invention.
In the wafer polishing method according to the present invention, as shown in FIG. 1, first, a polishing pad replacement threshold is set as an initial setting (STEP 1), a polishing pad is replaced (STEP 2), and 0 is set to cope with variations in pad thickness. By performing the point offset (STEP 3), the dresser movement amount can be measured (STEP 4). After the measurement of the movement amount of the dresser is started, the wear amount of the polishing pad is determined by periodically comparing the measured movement amount of the dresser and the threshold set in STEP 1 at an arbitrary timing (STEP 5). If the movement amount of the dresser is smaller than the threshold value, it is determined that the polishing pad replacement time has not been reached (STEP 5), and measurement of the dresser movement amount (STEP 4) is continued. If the movement amount of the dresser is equal to or greater than the threshold, it is determined that the polishing pad replacement time has been reached (STEP 5), and a polishing pad replacement instruction is notified (STEP 6). By this notification, it is possible to determine whether or not to replace the polishing pad at an optimal timing (STEP 7).
When the same type of polishing pad is used continuously, the threshold value setting (STEP 1) need only be performed once in the initial stage. However, when using different types of polishing pads, It is necessary to set a different threshold value again.

  FIG. 2 shows a timing chart when the wafer polishing method according to the present invention is carried out. The polishing pad replacement threshold is a shaded “alarm output range”, and the distance from the dresser standby position is set in advance before the measurement is started. After the measurement is started, when the movement amount of the dresser reaches a threshold value (alarm output range), a pad replacement instruction is notified (alarm output). After the polishing pad is replaced, the threshold value is reset to notify the replacement timing of a new polishing pad.

  A polishing apparatus according to the present invention includes an object holder for holding an object to be polished, a surface plate on which a polishing pad for polishing an object held by the holder is attached, and a dressing for the polishing pad. In a polishing device having a dresser, a pad wear amount measuring device that measures the amount of movement of the dresser composed of a laser displacement meter and a reflector, and whether or not the polishing pad needs to be replaced is determined based on the measurement result of the measuring device. And a polishing pad replacement time control unit.

  Embodiments of a wafer polishing apparatus according to the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

  As shown in FIG. 3, the polishing apparatus of this embodiment includes a polishing apparatus main body 10, a dressing apparatus 20, a polishing pad wear amount measuring apparatus 30, a polishing work control unit 40, and a polishing pad replacement time control unit 50. Yes. Hereinafter, details of each device and each part will be described.

《Polisher body》
The polishing apparatus body 10 includes a disk-shaped polishing surface plate 12, a polishing pad 11 affixed on the polishing surface plate 12, a polishing motor 13 that rotates the polishing surface plate 12, and a wafer that is an object to be polished. A disk-shaped object holder 14 for holding 16, an object holding / pressing head 15, and a polishing liquid nozzle 17 for supplying a polishing liquid onto the polishing pad 11.

《Dressing device》
The dressing device 20 includes a dresser (dress grindstone) 21 for dressing the polishing pad 11, a dresser holder 22 to which the dresser 21 is attached, a dress motor 24 that rotates the dresser holder 22, and a dresser holder 22. And an air cylinder 25 that moves up and down to change the dressing pressure of the dresser 21 against the polishing pad 11.

《Pad wear measurement device》
The polishing pad wear amount measuring device 30 is attached to a laser displacement meter 32 attached to a side wall of an air cylinder 25 fixed to a frame (not shown) and a bearing 26 that supports a dresser rotating shaft 23 of a dresser holder 22. The reflecting plate 31 is provided on the reflecting plate support portion 27. When the dresser 21 is moved up and down, the reflecting plate 31 is also moved up and down, so that the distance between the laser displacement meter 32 and the reflecting plate 31 changes. Since this change amount is equal to the lift amount of the dresser 21, the value can be measured by the laser displacement meter 32. Therefore, the wear amount of the polishing pad can be measured in a non-contact state, and can always be measured.

<Device body control unit>
The polishing operation control unit 40 includes a control calculation unit that executes various calculations for controlling the polishing apparatus body 10 and the dressing device 20, a storage unit that stores programs executed by the control calculation unit, various data, and the like. A control unit that displays a calculation result of the control calculation unit, a controller that outputs a drive control signal to the polishing apparatus body 10 and the dressing device 20 based on the calculation result of the control calculation unit, and an operator instruction And an input section to be provided to.

《Polishing pad replacement timing control unit》
The polishing pad replacement timing control unit 50 displays the result measured by the polishing pad wear amount measuring device 30, outputs an alarm when reaching a preset polishing pad limit wear amount, and replaces the polishing pad. It has a function to reset (reset to 0) the threshold value (displacement data) later.
Furthermore, since it has a terminal for outputting an analog signal synchronized with the display value of the wear amount data, it is possible to record the change over time of the wear amount by connecting a recorder or the like.

<Operation>
Next, an outline of the operation of the polishing apparatus according to the present embodiment will be described.
The polishing apparatus according to the present embodiment alternately performs wafer polishing with the polishing pad 11 and dressing of the polishing pad 11 with the dresser 21.
The polishing operation is performed by rotating the polishing pad 11 placed on the polishing surface plate 12 by the polishing motor 13, and the workpiece holding / pressing head 15 lowers the workpiece holder 14 and rotates the wafer 16. .
The dressing operation is performed by lowering the dresser 21 by the air cylinder 25 and rotating the dresser 21 by the dress motor 24.
At this time, the workpiece holder 14 and the dresser 21 are controlled by the polishing operation control unit 40 so as to keep the pressure constant.
Here, the polishing pad 11 is worn by both the polishing operation and the dressing operation.

  The polishing pad replacement timing control unit 50 outputs an alarm signal to the polishing operation control unit 40 when the limit wear amount is reached, thereby issuing an alarm on the polishing operation control unit 40 side and polishing operation. May be stopped.

  The polishing apparatus of this example can be used for polishing planar substrates such as silicon wafers, quartz substrates, and glass substrates, particularly silicon wafers during the LSI manufacturing process, and performance was confirmed by applying it to seven interlayer CMP devices. However, from the work aspect, 37% (33.0 minutes / day / vehicle) reduction of setup adjustment loss time, 19% (8.2 minutes / day / vehicle) reduction of inspection replacement loss time, and 34 of waiting loss time. % (18.2 minutes / day / vehicle) can be reduced, and a total of 59.4 minutes / day / vehicle is expected to be reduced. From the cost perspective, pad usage is reduced by 40% (6.8 million yen / 6 months). , 26% (2.9 million yen / 6 months) reduction in monitor wafer usage is expected.

Flow chart of wafer polishing method according to the present invention Timing chart of wafer polishing method according to the present invention Schematic of the wafer polishing apparatus according to this embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing apparatus main body 11 Polishing pad 12 Polishing surface plate 13 Polishing motor 14 Polishing object holder 15 Polishing object holding / pressing head 16 Wafer 17 Polishing liquid nozzle 20 Dressing device 21 Dresser 22 Dresser holder 23 Dresser rotating shaft 24 Dress motor 25 Air cylinder 26 Bearing 27 Reflecting plate support unit 30 Polishing pad wear amount measuring device 31 Reflecting plate 32 Laser displacement meter 40 Polishing work control unit 50 Polishing pad replacement time control unit

Claims (8)

  In a polishing method that alternately polishes the workpiece with the polishing pad and dresses the polishing pad with a dresser, a polishing pad replacement threshold is set, and the amount of wear of the polishing pad is measured based on the amount of movement of the dresser. A polishing method characterized in that the polishing pad replacement time is determined by comparing the measurement result with the polishing pad replacement threshold.   The polishing method according to claim 1, further comprising: resetting a polishing pad replacement threshold after replacing the polishing pad, and determining a replacement timing of the polishing pad after replacement.   The polishing method according to claim 1, wherein the object to be polished is a silicon wafer. An object holder for holding an object to be polished, a polishing surface plate to which a polishing pad for polishing the object to be polished held by the object holder to be polished is attached, and a dressing for the polishing pad In a polishing apparatus having a dresser and an apparatus control unit,
A polishing apparatus having a function of measuring a movement amount of the dresser and determining whether or not the polishing pad needs to be replaced based on the measurement result.   The measurement result of the movement amount of the dresser is compared with a preset polishing pad replacement threshold value, and when the measurement result exceeds the threshold value, a function of notifying a polishing pad replacement instruction is provided. Item 5. The polishing apparatus according to Item 4.   The polishing apparatus according to claim 5, wherein the polishing apparatus has a function of resetting a polishing pad replacement threshold after the polishing pad is replaced.   The polishing apparatus according to claim 4, further comprising a polishing pad replacement timing control unit that determines whether or not the polishing pad needs to be replaced based on a measurement result of the movement amount of the dresser. The polishing apparatus according to claim 4, wherein the object to be polished is a silicon wafer.

Images