JP2001334461A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device measuring a polishing quantity of a polishing surface during polishing a substrate to be polished or dressing the polishing surface without dispersing pollution by the polishing quantity measuring of the polishing surface and to appropriately decide a replacement timing of the polishing face component material. SOLUTION: This polishing device urges the substrate 5 to be polished held by a top ring 4 to the polishing face of a polishing pad 2 of a turn table 1 and polishes the substrate to be polished by the relative movement between the polishing pad 2 and the substrate 5 to be polished and dresses the polishing surface by a dresser. The rotary shaft 6 of the top ring 4 or the rotary shaft of the dresser is provided with a target 7 for measuring the polishing surface polishing quantity, the displacement of the target 7 is measured, and the polishing quantity of the polishing face is detected by the measured displacement so that the dressing timing and the polishing pad replacement timing are decided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing a substrate such as a semiconductor wafer, and more particularly to a polishing apparatus for polishing a polishing member such as a polishing pad or a grindstone plate (polishing plate containing abrasive grains) constituting a polishing surface of a turntable. The present invention relates to a polishing apparatus provided with an amount measuring means.

[0002]

2. Description of the Related Art A conventional polishing apparatus of this type includes a turntable provided with a polishing member constituting a polishing surface such as a polishing pad or a grindstone plate on an upper surface, and a substrate holding mechanism for holding a substrate to be polished such as a semiconductor wafer. And a dresser mechanism for dressing the polishing surface of the polishing member. Then, the substrate to be polished held by the substrate holding mechanism is pressed against the polished surface, and the substrate to be polished is polished to a flat mirror surface by the relative movement between the polished surface and the substrate to be polished. The polished surface is dressed with a dresser mechanism to regenerate and modify dressing.

In the polishing apparatus having the above structure, the dressing is for regenerating and modifying the polished surface, so that the polishing member is consumed and the polishing efficiency is increased unless the polished surface is dressed at an appropriate time. Is hindered. In addition, it is necessary to appropriately determine the time to replace the polishing member. For that purpose, it is necessary to quickly and accurately detect the shaved amount of the polishing surface of the polishing member.

Conventionally, the measurement of the abrasion amount of the polished surface of the polishing member has been performed by bringing a displacement measuring sensor into contact with the polished surface of the polishing member. However, since the polishing liquid or the like is supplied to the polishing surface of the polishing member, and there is shavings of the substrate to be polished and the polishing member, there is a problem that contamination is diffused every time the shaving amount is measured. In addition, there is a problem that the measurement is time-consuming because the displacement measurement sensor is brought into contact with the polishing surface and the measurement is performed while moving the polishing surface.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and there is no diffusion of contamination by measuring the amount of abrasion on a polished surface, and polishing is performed during polishing of a substrate to be polished or dressing of a polished surface. It is an object of the present invention to provide a polishing apparatus that can measure the amount of abrasion of a polished surface of a member, and can appropriately determine a dressing time and a replacement time of a polishing member.

[0006]

According to a first aspect of the present invention, there is provided a turntable having a polishing member constituting a polishing surface, a substrate holding mechanism for holding a substrate to be polished, and a polishing member. A dresser mechanism for dressing the polished surface is provided, the substrate to be polished held by the substrate holding mechanism is pressed against the polished surface, and the substrate to be polished is polished by the relative movement between the polished surface and the substrate to be polished. A polishing apparatus for dressing a polishing surface, wherein a target is provided at a portion whose position is displaced in accordance with an amount of shaving of the polishing member in a non-contact manner with a polishing surface of a substrate holding mechanism or a dresser mechanism, and a displacement amount of the target is provided. And a polishing member scraping amount detecting means for detecting a scraping amount of the polishing member from the measured displacement amount is provided.

[0007] As described above, the abrasive member scraping amount detecting means is provided, and the amount of scraping of the polishing member is detected from the amount of displacement of the target provided in the substrate holding mechanism or the dresser mechanism. It can be detected in real time during polishing or dressing of the polished surface. Also,
Since the target for measuring the abrading member abrasion amount is provided in a portion that is not in contact with the abrading surface and is displaced in accordance with the abrading amount of the abrading surface, contamination occurs each time the abrading amount of the abrading member of the abrading member is measured. There is no problem of diffusion.

According to a second aspect of the present invention, in the polishing apparatus of the first aspect, the polishing member scraping amount detecting means has a function of measuring a displacement amount of the target without contacting the target. And

As described above, the polishing member scraping amount detecting means has a function of measuring the displacement amount of the target in a non-contact manner with the target. Therefore, even if the target is provided on the rotating portion of the substrate holding mechanism or the dresser mechanism, it can be fixed from the fixed side. The displacement can be easily measured.

[0010] The invention described in claim 3 is the invention according to claim 1 or 2.
Wherein the polishing member scraping amount detecting means has a function of measuring the polishing surface scraping amount from the displacement amount of the target measured when the polishing surface pressing force of the substrate holding mechanism or the dresser mechanism is equal to or less than a predetermined value. It is characterized by the following.

As described above, the abrasive member scraping amount detecting means is
Since the polishing surface scraping amount of the polishing member is measured from the displacement amount of the target measured when the polishing surface pressing force of the substrate holding mechanism or the dresser mechanism is equal to or less than a predetermined value, even when the polishing member is made of a material that elastically deforms, The amount of shaving on the polished surface can be detected in a state where there is little.

The invention described in claim 4 is the first invention.
Alternatively, in the polishing apparatus described in 2 or 3, the polishing member scraping amount detecting means has a dressing timing determination function of determining a dressing timing of the polishing surface from the measured displacement of a target provided in the substrate holding mechanism or the dresser mechanism. It is characterized by the following.

As described above, the abrasive member scraping amount detecting means is
A dressing time determination function for determining the dressing time of the polished surface of the polishing member from the measured displacement of the target provided on the substrate holding mechanism is provided, so that the dressing of the polished surface can be executed at an appropriate time, and always efficient polishing can be performed. And the consumption of the polishing member can be reduced.

The invention described in claim 5 is the first invention.
5. The polishing apparatus according to claim 1, wherein the polishing member scraping amount detecting means determines a polishing member replacement time based on the measured displacement of a target provided on the substrate holding mechanism or the dresser mechanism. Since the determination member is provided, it is possible to replace the polishing member at an appropriate time, and it is not necessary to replace a polishing member that can still be used, or to damage a device or a substrate to be polished by delaying the replacement time.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a polishing apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a turntable. A polishing pad 2 is attached to an upper surface of the turntable 1, and the turntable 1 is rotated in a direction of an arrow A by a turntable rotating shaft 3. Reference numeral 4 denotes a top ring for holding a substrate 5 to be polished such as a semiconductor wafer at the lower end. The top ring 4 is attached to a lower end of a top ring rotating shaft 6 so that the top ring 4 rotates in the direction of arrow B by the top ring rotating shaft 6. It has become. The top ring 4 is rotatably supported by a top ring head 14, and the top ring head 14 is vertically moved by a cylinder 15.

The substrate 5 to be polished is held at the lower end of the top ring 4 rotating in the direction of arrow B, and pressed against the upper surface of the polishing pad 2 of the turntable 1 rotating in the direction of arrow A, thereby polishing the substrate 5 to be polished. The lower surface of the substrate 5 to be polished is polished flat and mirror-like by the relative movement of the pad 2. When a predetermined number of substrates to be polished are polished, the polished surface of the polishing pad 2 is scraped off by abrasion and dressing.
From the portion 2a that does not contribute to the polishing of the surface, the amount of shaving (displacement) d
Only thinner.

Since the polishing rate of the polishing pad 2 decreases due to aging or clogging due to polishing, the polishing pad 2 is dressed at a predetermined timing to scrape the surface to regenerate the dressing.
It needs to be modified. In this dressing, since the pad surface is shaved, if the timing of the dressing is too early, the polishing pad 2 is greatly consumed, and the polishing pad 2 is wasted. If the timing of the dressing is too late, the polishing rate decreases, and the polishing efficiency of the substrate 5 to be polished decreases. Further, when the shaving amount d of the polishing pad 2 advances by a predetermined amount or more, it is necessary to replace the polishing pad 2 with a new one. In order to perform the above-mentioned dressing at an appropriate timing, and also to perform the replacement timing of the polishing pad 2 at an appropriate time, the amount of shaving of the polishing pad 2 is quickly and rapidly reduced.
And it is necessary to measure accurately.

Here, a disk-shaped target 7 is provided on the top ring rotating shaft 6, and a displacement measuring head 8 for measuring the amount of vertical displacement of the target 7 is provided facing the target 7. The displacement measuring head 8 is fixed to a fixed body 17 such as an apparatus frame via a bracket 16. The displacement measuring head 8 uses, for example, a laser beam,
The vertical displacement of the target 7 is detected without contact. The output of the displacement measuring head 8 is sent to a displacement meter 9 as shown in FIG. 2, where the displacement amount Sd of the target 7 is calculated,
The calculated displacement is converted into a digital signal Sd ′ by the A / D converter 10 and sent to the computer 11. The computer 11 receives a pressing force signal P and the like for pressing the top ring 4 against the substrate 5 to be polished. The memory (not shown) of the computer 11 stores a displacement amount Δd of the polishing surface that requires one dressing, a displacement amount D that requires replacement of the polishing pad 2, and the like.

The computer 11 subtracts the displacement d _n-1 at the end of the previous dressing from the measured displacement d _n of the polishing pad 2 (d _n -d _n-1 ). When more than the amount _{Δd (Δd ≧ d n -d n} -1), and outputs a signal S1 to the effect that running the dressing to the controller of the polishing apparatus to perform the dressing. If the current displacement amount d _n exceeds the exchange shaving amount (displacement amount D) (d _n ≧ D), a polishing pad exchange signal S2 is output.

When the polishing pad 2 is made of a material that is elastically deformed, there is a problem that if the pressing force P of the top ring 4 is large, the polishing pad 2 is elastically deformed, and it is not possible to accurately measure the shaved amount. Therefore, when the pressing force P is small and the elastic deformation is as small as possible, it is necessary to measure the shaving amount.
The shaving amount is measured when the pressing force of the top ring 4 is equal to or less than a predetermined value. For example, as shown in FIG. 3, when the pressing force P is changed and the substrate to be polished 5 is polished as time t elapses, the shaving amount is measured at a time tx where the pressing force is small.

As described above, the removal amount of the polishing surface of the polishing pad 2 is detected from the displacement amount of the target 7 provided on the top ring rotating shaft 6, so that the removal amount of the polishing surface can be determined in real time during polishing of the substrate 5 to be polished. Can be detected. Also,
Since the target 7 is provided on the top ring rotating shaft 6, there is no problem that contamination is diffused every time the amount of abrasion of the polished surface is measured as in the related art. In addition, the mounting position of the target 7 is not limited to the top ring rotating shaft 6, but may be, for example, the top ring 4 or the top ring 4 if the position is displaced according to the shaving amount of the polishing surface without contacting the polishing surface. A top ring support arm (not shown) or the like may be used.

As described above, since the computer 11 determines the dressing time of the polishing surface of the polishing pad 2 from the measured displacement of the target 7, the dressing of the polishing surface can be executed at an appropriate time, and efficient polishing is always performed. Can be implemented. Further, the amount of consumption of the polishing pad 2 can be reduced. Further, since the replacement time of the polishing pad 2 is determined from the displacement amount of the target 7, the polishing member can be replaced at an appropriate time,
It is no longer necessary to replace the polishing pad 2 that can still be used, or to damage the equipment or the substrate to be polished due to the delay of replacement.

FIG. 5 is a diagram showing a flow of a processing example from the replacement of the polishing pad to the replacement of the next polishing pad. First, the polishing pad is replaced (step ST1), and this is notified to the control unit of the apparatus. Thereby, the control unit lowers the top ring 4 to the polishing position, and performs the first polishing and the first dressing (in some cases, the dummy polishing and the dressing by the dummy wafer) (steps ST2 and ST2).
3). Next, the initial height H ₀ of the target 7 is measured by the displacement measuring head 8 (step ST4). Next, polishing of the substrate to be polished and dressing of the polished surface after polishing are performed (steps ST5 and ST6), and the height H of the target 7 is measured each time the polishing and dressing are completed (step ST7). (In the above example, when the displacement amount of the polishing pad 2 reaches the displacement amount Δd of the polishing surface that requires dressing, dressing of the polishing surface is performed. Here, the dressing is performed every time polishing is completed. Do.)

Subsequently, it is determined whether or not the shaving amount of the polishing pad 2 (the displacement amount Δd = H ₀ -H of the polishing surface) has reached a set value (the displacement amount D requiring replacement of the polishing pad 2). (Step ST8) If the set value is not reached, the aforementioned step S8 is performed.
The processing from T5 is repeated, and when the set value is reached, it is determined whether or not an alarm is set (step ST9). When the set value is set, it is notified that the shaved amount of the polishing pad 2 has reached the replacement time. An alarm process is performed (step ST10),
The process from step ST5 is repeated, and if no alarm is set, the failure or the process is interrupted and the substrate to be processed (for example, a semiconductor wafer) is collected (step ST11).

Setting of the above alarm processing, failure or interruption of processing
The process for collecting the substrate to be processed is arbitrarily set by the user. In the above example, the height H of the target 7 is measured for each polishing and dressing, but the height H of the target 7 may be measured for each polishing and dressing several times. Also, the height H of the target 7
May be measured after the polishing process is completed.

In the polishing apparatus shown in FIG. 1, the displacement of the target 7 in the vertical direction is measured by a displacement measuring head.
Thereby, the vertical vibration of the top ring 4 is detected, and the dressing time of the polishing surface of the polishing pad 2 and the replacement time of the polishing pad can be determined based on the vibration characteristics. FIG. 6 is a diagram showing the relationship between the polishing time and the vertical vibration of the top ring 4. As shown in the figure, when the polishing time has elapsed and the clogging of the polished surface proceeds, the frictional force decreases, and the vertical vibration width of the top ring 4 decreases.

Therefore, as shown in FIG. 7, the output signal of the displacement measuring head 8 representing the vertical vibration of the top ring 4 is converted into a digital signal by the A / D converter 21 and sent to a separately installed personal computer or device control unit 22. When the vertical vibration width becomes equal to or less than a predetermined value by a separate personal computer or the device control unit 22, it is determined that the polishing surface of the polishing pad 2 is clogged, and dressing is performed.

As the polishing surface of the polishing pad 2 wears, the frictional force between the substrate to be polished and the polishing surface increases, and the vertical vibration of the top ring 4 increases as shown in FIG. Therefore, in the processing system having the configuration shown in FIG. 7, when the vertical vibration width of the top ring 4 is equal to or larger than the predetermined value L, the separate PC or the device control unit 22 determines that it is time to replace the polishing pad.

The vertical vibration width of the top ring 4 requiring dressing and the vertical vibration width of the top ring 4 requiring replacement of the polishing pad 2 are arbitrarily set by a user. The placing personal computer or the device control unit 22 determines the time for dressing the polishing surface and the time for replacing the polishing pad. In the vertical vibration measurement of the top ring 4, the pressing force and the rotation speed of the top ring 4 and the rotation speed of the polishing surface are measured under the same conditions.

FIG. 9 shows a separate PC or device control unit 22.
It is a figure which shows the processing flow of judgment of dressing time and automatic dressing in FIG. First, polishing is started (basically, the same substrate to be processed is polished) (step ST2).
1). The amplitude width of the top ring 4 is measured from the output of the displacement measuring head 8 (step ST22). It is checked whether the number of times of amplitude width measurement (number of times of sampling) is equal to or more than n times (step ST23). If the number of times has not reached n times, the measurement is repeated until it reaches n times. Is less than or equal to the set amplitude width X (Arang <) that requires dressing of the polishing surface of the polishing pad.
X) is checked (step ST24), and if the measured amplitude width average value Arang is not equal to or smaller than the set amplitude width X, the processes of steps ST22 to ST23 are repeated until the average amplitude width becomes equal to or smaller than X. Note that the value of the set amplitude width X can be arbitrarily set by the user.

If the measured amplitude width average value Arang is equal to or smaller than the set amplitude width X, it is next checked whether or not automatic dressing is set (step ST25). If automatic dressing is set, top ring is set. 4 is evacuated (polishing interrupted) (step ST26), and dressing is started (step ST27). When the dressing is completed, the process proceeds to step ST21, and polishing is performed. If automatic dressing is not set in step ST25, an alarm is issued to notify that it is time to dress the polishing surface of the polishing pad (step ST29).

The completion of polishing is determined by polishing time (for example, 2 minutes) or end point detection (measurement of film thickness by vibration or light).
Thus, it is managed separately from the dressing processing timing. In the processing flow shown in FIG. 5, dressing is performed each time polishing of one substrate to be polished is completed. However, dressing may not always be necessary. In some cases, for example, when a semiconductor wafer on which a thick Cu plating layer is deposited is polished as a substrate to be polished, the polishing time may be long (for example, 5 minutes). In such a case, it is necessary to determine the dressing time even during polishing of the substrate to be polished, and the process shown in FIG. 9 is effective in such a case.

In the above embodiment, the target 7
Is provided on the top ring rotation shaft 6, but is not limited to this. As shown in FIG. 4, the displacement measurement head 8 is provided on the dresser rotation shaft 13 of the dresser 12 when dressing the polishing surface of the polishing pad 2. The amount of scraping may be measured via the. The processing system for the output signal of the displacement measuring head 8 is the same as the configuration shown in FIG. In FIG. 4, reference numeral 18 denotes a dresser head, 19 denotes a cylinder, and 20 denotes a bracket for fixing the displacement measuring head 8 to the fixed body 17.

As described above, the amount of shaving of the polishing surface of the polishing pad 2 is detected from the amount of displacement of the target 7 provided on the dresser rotating shaft 13, so that the amount of shaving of the polishing surface can be detected in real time during dressing. . Further, since the target 7 is provided on the dresser rotation shaft 13, there is no problem that contamination is diffused every time the amount of abrasion of the polished surface is measured as in the related art. Note that the position where the target 7 is provided is not limited to the dresser rotating shaft 13. For example, the top ring 4 or the top ring 4 may be used as long as the position is displaced according to the amount of shaving of the polishing surface without contacting the polishing surface. A ring support arm (not shown) or the like may be used.

In the above example of the polishing apparatus, an example in which the polishing pad 2 is attached as a constituent member of the polishing surface on the upper surface of the turntable 1 has been described. However, the polishing apparatus targeted by the present invention is not limited to this. Instead, a whetstone plate (a polishing plate containing abrasive grains) may be provided on the upper surface of the turntable 1.

[0036]

As described above, according to the invention described in each claim, the following effects can be obtained.

According to the first aspect of the present invention, the abrasive member scraping amount detecting means is provided, and the amount of grinding of the polishing member is detected from the displacement amount of the target provided in the substrate holding mechanism or the dresser mechanism. The amount of shaving can be detected in real time during polishing of the substrate to be polished or dressing of the polished surface. In addition, since the target for measuring the amount of scraping of the polishing member is provided in a portion where the position is displaced in accordance with the amount of scraping of the polishing member without contacting the polishing surface, the amount of scraping is measured while contacting the polishing surface as in the related art. Unlike the one, there is no problem that the contamination is diffused each time the shaved amount is measured.

According to the second aspect of the present invention, since the polishing member scraping amount detecting means has a function of measuring a displacement amount of the polishing member without contacting the target, the target is mounted on the rotating portion of the substrate holding mechanism or the dresser mechanism. Even if it is provided, the displacement amount can be easily measured from the fixed side.

According to the third aspect of the present invention, the polishing member scraping amount detecting means determines the polishing member scraping amount from the target displacement measured when the polishing surface pressing force of the substrate holding mechanism or the dresser mechanism is below a predetermined value. Since the measurement is performed, even if the polishing member is made of a material that is elastically deformed, the amount of scraping of the polishing member can be detected with little elastic deformation.

According to the fourth aspect of the present invention, there is provided a dressing timing determining function for determining a dressing timing of a polished surface from a displacement of a target provided in a substrate holding mechanism or a dresser mechanism measured by a polishing member scraping amount detecting means. Since it is provided, dressing of the polishing surface can be executed at an appropriate time, efficient polishing can be always performed, and consumption of the polishing member can be reduced.

Further, according to the fifth aspect of the present invention, a polishing member replacement which determines a replacement time of a polishing member from a displacement amount of a target provided on a substrate holding mechanism or a dresser mechanism measured by a polishing member scraping amount detecting means. Since the timing determination function is provided, the polishing member can be replaced at an appropriate time, and there is no need to replace a polishing member that can still be used, or to damage a device or a substrate to be polished by delaying the replacement time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a top ring and a turntable of a polishing apparatus according to the present invention.

FIG. 2 is a diagram showing a system configuration of an apparatus for processing an output of a displacement measuring head.

FIG. 3 is a diagram illustrating an example of a relationship between a pressing force of a substrate to be polished and time during polishing of the substrate to be polished;

FIG. 4 is a diagram showing a schematic configuration of a dresser and a turntable of the polishing apparatus according to the present invention.

FIG. 5 is a diagram showing an example of a processing flow from replacement of a polishing pad to replacement of the next polishing pad in the polishing apparatus according to the present invention.

FIG. 6 is a diagram showing a relationship between a polishing time and a change in vibration of a top ring in a vertical direction.

FIG. 7 shows a dressing timing based on an output of a displacement measuring head,
It is a figure showing the example of composition of the system which judges a polishing pad exchange time.

FIG. 8 is a diagram showing a relationship between a polishing time and a change in vibration of a top ring in a vertical direction.

FIG. 9 is a diagram showing an example of a dressing timing determination and automatic dressing processing flow of a polishing surface of a polishing pad in the polishing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turntable 2 Polishing pad 3 Turntable rotation axis 4 Top ring 5 Substrate to be polished 6 Top ring rotation axis 7 Target 8 Displacement measurement head 9 Displacement meter 10 A / D converter 11 Computer 12 Dresser 13 Dresser rotation axis 14 Top ring head 15 Cylinder 16 Bracket 17 Fixed body 18 Dresser head 19 Cylinder 21 A / D converter 22 Separately installed personal computer or device control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 622 H01L 21/304 622M 622S

Claims (5)

[Claims] A turntable having a polishing member constituting a polishing surface; a substrate holding mechanism for holding a substrate to be polished;
A dresser mechanism for dressing the polished surface of the polishing member; pressing the substrate to be polished held by the substrate holding mechanism on the polished surface; polishing the polished substrate by relative movement between the polished surface and the polished substrate; And a polishing apparatus for dressing a polishing surface with the dresser, wherein the target is placed on a portion of the substrate holding mechanism or the dresser mechanism whose position is displaced in a non-contact manner with the polishing surface of the polishing member in a non-contact manner. A polishing apparatus, further comprising: a polishing member scraping amount detecting means for measuring a displacement amount of the target and detecting a scraping amount of the polishing member from the measured displacement amount. 2. The polishing apparatus according to claim 1, wherein the polishing member scraping amount detecting means has a function of measuring a displacement amount of the target without contacting the target. 3. The polishing apparatus according to claim 1, wherein the polishing member scraping amount detecting means is configured to measure a displacement amount of the target measured when a pressing force of the polishing surface of the substrate holding mechanism or the dresser mechanism is equal to or less than a predetermined value. A polishing apparatus having a function of measuring the amount of polished surface scraping from the surface. 4. The polishing apparatus according to claim 1, wherein the polishing member scraping amount detecting means determines a dressing time of a polishing surface based on a measured displacement amount of a target provided on the substrate holding mechanism or the dresser mechanism. A dressing time determining function for determining the polishing time. 5. The polishing apparatus according to claim 1, wherein the polishing member scraping amount detecting means is configured to determine the polishing amount based on a measured displacement amount of a target provided on the substrate holding mechanism or the dresser mechanism. A polishing apparatus comprising a polishing member replacement time determination function for determining a replacement time of a member.