WO2015015705A1

WO2015015705A1 - Wafer polishing method and wafer polishing device

Info

Publication number: WO2015015705A1
Application number: PCT/JP2014/003414
Authority: WO
Inventors: 三千登佐藤; 上野　淳一; 薫石井
Original assignee: 信越半導体株式会社
Priority date: 2013-07-29
Filing date: 2014-06-26
Publication date: 2015-02-05
Also published as: TW201517147A; JP2015026794A; JP6083346B2

Abstract

This invention is a wafer polishing method, namely an indexed polishing method in which a plurality of polishing heads, a plurality of platens to which polishing cloths are bonded, and a loading/unloading stage for attaching and detaching wafers to and from the polishing heads are prepared, the platens and the loading/unloading stage are arranged concentrically, and the polishing heads are rotated, thereby simultaneously polishing a plurality of wafers while switching up the platens used therefor. Said wafer polishing method is characterized in that after polishing of a wafer is interrupted by a platen switch, polishing of said wafer resumes within 15 seconds, and after a wafer is done being polished, the operation of detaching said wafer from the polishing head starts within 15 seconds. This results in a polishing method in which the characteristic haze irregularity that occurs in index polishing devices during the polishing step and between the completion of polishing and the beginning of the detachment operation can be prevented effectively.

Description

Wafer polishing method and wafer polishing apparatus

The present invention relates to an index-type wafer polishing method and a wafer polishing apparatus for preventing haismura.

For polishing a semiconductor wafer typified by a silicon wafer, as shown in FIG. 6, a surface plate 102 on which a polishing cloth 105 is attached, and an abrasive supply mechanism for supplying an abrasive 106 onto the surface plate 102. A polishing apparatus 101 including a polishing head 104 for holding a wafer W to be polished 103 and a wafer W to be polished is often used. The polishing apparatus 101 holds the wafer W with the polishing head 104, supplies the polishing agent 106 from the polishing agent supply mechanism 103 onto the polishing cloth 105, and rotates the surface plate 102 and the polishing head 104, respectively. Polishing is performed by sliding on the polishing cloth 105.
In addition, the polishing of the semiconductor wafer is often performed in multiple stages by changing the type of polishing cloth and the type of polishing agent, and the polishing process performed in the final stage is called finish polishing or final polishing.

As a polishing apparatus used for polishing a semiconductor wafer, a polishing apparatus having a plurality of surface plates generally called an index method is often used from the viewpoint of productivity. FIG. 7 shows an index type polishing apparatus. A polishing apparatus 201 having a plurality of

surface plates

207, 208, and 209 often has a larger number of polishing shafts for rotating the polishing head than the number of surface plates. Since loading (unloading) and unloading (peeling) of the wafer W to the head can be performed, productivity can be improved. In such a polishing apparatus 201, a method is used in which each polishing axis is rotated around a central axis 202. FIG. 7 shows a case where each polishing shaft is in an initial position before starting the turning movement.

Further, in the index type polishing apparatus, the movement of the polishing head during the pivotal movement differs depending on the polishing axis in order to protect various wirings.
For example, in the case of an index type polishing apparatus having three surface plates as shown in FIG. 7, the number of polishing axes to which the polishing head 206 is attached is 4 axes × n or more (4 axes in the case of the polishing apparatus 201 in FIG. 7). If the polishing axis whose initial position is the position of the loading / unloading stage 205 is the first polishing axis 204, the first polishing axis 204 is positioned at the loading / unloading stage 205 as shown in FIG. As a reference, 0 degrees (loading / unloading stage 205 position) → 90 degrees (first surface plate 207 position) → 180 degrees (second surface plate 208 position) → 270 degrees (third surface plate 209 position) → The wafer is polished while the first polishing head 206 is pivoted and moved at 0 degree (loading / unloading stage 205 position). That is, when the polishing is completed at the position of 270 degrees (the third platen 209 position), the wafer W is turned in the opposite direction and returned to the loading / unloading stage 205 position to start the peeling operation of the wafer W from the polishing head. . The peeling operation is usually performed by spraying a water flow from the nozzle onto the edge portion of the wafer. The peeled wafer is dropped onto an unloading stage filled with water, and then transferred to the next step such as a water tank or a cleaning tank by a robot or the like. The first, second, third, and fourth polishing axes in FIG. 8 are the first polishing axis 204, the second polishing axis 210, the third polishing axis 211, and the fourth polishing axis in FIG. 212 respectively.

After the final polishing process is completed, the wafer is cleaned using ultrasonic waves or chemicals, and then inspected for particles and haze using a particle measuring instrument such as KLA-Tencor. The particle measuring device can output a difference in in-plane haze as a haze map. This haze map is often output on an autoscale to facilitate determination of surface unevenness, and unevenness becomes more visible as the haze level decreases.

For this reason, conventionally, in order to prevent the manifestation of haismura that is confirmed when output in an auto scale, the hydrophilic agent contained in the final polishing agent is adjusted, and the protective film on the wafer surface after polishing is strengthened. I was taking measures. Further, in Patent Document 1, in order to prevent local etching by the abrasive attached to the wafer surface, the polished wafer is put into a cleaning tank within 40 seconds after finishing polishing, or finish polishing. A method is described in which a mist-like shower or a low-pressure shower is performed on the finished wafer surface, and the wafer surface is cleaned with an abrasive.

JP 2004-265906 A

As described above, when a wafer is polished using, for example, the index-type polishing apparatus 201 shown in FIG. 7, each polishing shaft may be rotated 90 degrees or 270 degrees until the next step. The time is different in each case. The wafer of the first polishing shaft 204 is rotated 270 degrees in the reverse direction to the unloading position after the final polishing by the third surface plate 209, so that the wafer is being rotated during the rotation after the polishing is completed. The time during which the polishing agent attached to the surface is subjected to the etching action becomes longer, and the haze is more likely to occur as compared with wafers with other polishing axes. The cause of this hazmla is abrasive bubbles remaining on the polished surface of the wafer. This bubble is removed by the peeling operation. However, since the state of adhesion of the abrasive is different between the part with and without the bubble on the polishing surface of the wafer, the bubble is removed by etching of the abrasive before the peeling operation. A part or the whole of the pattern remains on the polished surface of the wafer and is observed as hazyness.

Furthermore, since each polishing shaft has a different initial position, the timing for performing the reverse rotation of 270 degrees is different. As described above, since the first polishing shaft 204 rotates by 270 degrees after polishing, the surface of the wafer after polishing is etched. Since the second polishing shaft 210 and the third polishing shaft 211 are rotated by 270 degrees in the middle of the polishing step before the polishing is completed, the wafer surface is etched by the polishing agent during the rotation movement, and haismura is generated. However, in many cases, the haze irregularity is corrected in the next polishing step. Since the fourth polishing shaft 212 performs a 270-degree turning movement before the start of polishing, all the turning movements from the interruption of polishing to the resumption of polishing are 90 degrees, and the etching time during the turning movement is short. This is an ideal operation that is unlikely to occur. Accordingly, due to the mechanical mechanism of the polishing apparatus 201, the first polishing shaft 204 is most likely to occur, and the fourth polishing shaft 212 is least likely to occur.

FIG. 9 shows an example of a haze map of a wafer polished while being held by a polishing head at the position of each polishing axis among a plurality of wafers having a diameter of 300 mm polished using an index type polishing apparatus. It can be seen that the polished surface of the wafer polished by the first polishing shaft 204 is generally uneven. The polished surfaces of the wafers polished by the second polishing shaft 210 and the third polishing shaft 211 are uniform as a whole, but a partially uneven pattern can be seen in the circled portion in the figure. . Such unevenness is not observed on the polished surface of the wafer polished by the fourth polishing shaft 212.
In particular, the hazyness of the wafer of the first polishing shaft 204 becomes more prominent in a large-sized polishing apparatus capable of polishing with a diameter of 450 mm, and becomes a level that is unsatisfactory in the determination of hazyness using an autoscale map. This is presumably because the larger the polishing apparatus, the longer the swivel movement time and the longer the etching time for the abrasive. An example of this Heismura is shown in FIG.

In this way, a difference occurs in the haze map of the polished surface of the polished wafer depending on which polishing axis is used for polishing. In particular, a wafer polished by the first polishing axis 204 is polished by another polishing axis. There has been a mechanical problem that haismura is more likely to occur than a fabricated wafer.

In recent years, the demand for improving the smoothness of the wafer surface has increased, and the haze level has greatly improved due to the introduction of brush cleaning with low etching power for cleaning after polishing. Along with this, the haze irregularity between the polishing axes peculiar to the index type polishing apparatus when polishing with the index type polishing apparatus has become a problem. In particular, in a large polishing apparatus capable of polishing a wafer having a diameter of 450 mm, the haze generated at the first polishing shaft 204 as shown in FIG. 10 has been recognized as an obvious abnormality.

Further, since the method described in Patent Document 1 is a method for managing the time until the cleaning tank is put into the wafer after finish polishing, or using a shower or a low-pressure shower that is atomized before cleaning, as shown in FIG. As shown in (1), it is impossible to prevent the hazy irregularity caused by the difference in the rotational movement time of each polishing shaft in the index method. Therefore, even if it is the same product, there existed a problem that a different haze pattern was mixed for every grinding | polishing axis | shaft used for grinding | polishing.

The present invention has been made in view of the above-described problems, and can effectively prevent the hazy irregularity that occurs during the polishing step and after the end of polishing until the start of the peeling operation, which is peculiar to the index type polishing apparatus. An object is to provide a polishing method.

To achieve the above object, according to the present invention, a plurality of polishing heads for holding a wafer, a plurality of surface plates to which a polishing cloth for polishing the wafer is attached, and the wafer A loading / unloading stage is prepared for mounting to the polishing head or peeling from the polishing head, the plurality of surface plates and the loading / unloading stage are arranged concentrically, and the polishing head is swung. An index method for polishing a plurality of wafers simultaneously while switching the surface plate used for polishing the wafer held by the polishing head, wherein the polishing of the wafer is interrupted when the surface plate is switched. The time until the polishing is resumed later and after the polishing of the wafer is finished, It provides a method of polishing a wafer, which comprises a time until the operation start within 15 seconds.

Thus, by shortening the time from the interruption of polishing to the resumption of polishing and the time from the end of polishing to the start of the peeling operation, the time for etching the polished surface of the wafer with the abrasive can be shortened. As a result, it is possible to prevent a part or the whole of the foam pattern of the abrasive from remaining on the wafer polished surface by the etching action of the abrasive attached to the polished surface of the wafer, and thus it is possible to effectively prevent the occurrence of hazyness.

Further, according to the present invention, a plurality of polishing heads for holding a wafer, a plurality of surface plates to which a polishing cloth for polishing the wafer is attached, and mounting of the wafer to the polishing head or the A loading / unloading stage for peeling from the polishing head is provided, the plurality of surface plates and the loading / unloading stage are arranged concentrically, and by rotating the polishing head, the polishing head An index-type polishing apparatus that simultaneously polishes a plurality of wafers while switching the surface plate used for polishing the wafer held by the wafer, and the time from when the polishing of the wafer is interrupted to when polishing is resumed when the surface plate is switched And the time from the end of polishing of the wafer to the start of the peeling operation from the polishing head. To provide a polishing apparatus of a wafer, characterized in that those within 5 seconds.

In such a case, it is possible to shorten the time from the interruption of polishing to the resumption of polishing and the time from the end of polishing to the start of the peeling operation, and shorten the time during which the polishing surface of the wafer is etched by the abrasive. be able to. As a result, it is possible to prevent part of or the entire foam pattern of the abrasive from remaining on the polished surface of the wafer by the etching action of the abrasive attached to the polished surface of the wafer. It becomes.

With the index-type polishing method and polishing apparatus of the present invention, the time from the interruption of wafer polishing when switching the surface plate to the restart of polishing and the time from the end of polishing to the start of the peeling operation are shortened to within 15 seconds. As a result, the time during which the polished surface of the wafer is etched by the abrasive can be shortened. As a result, it is possible to effectively prevent the occurrence of hazyness on the polished surface of the wafer.

1 is a schematic view illustrating an index type polishing apparatus of the present invention. It is the schematic which shows a part of index type polisher of the present invention. It is a flowchart which shows an example of the rotational movement method of each grinding | polishing axis | shaft in the grinding | polishing method of this invention. It is the figure which showed the incidence rate of Haismura in Examples 1 and 2 and Comparative Examples 1 and 2. It is the figure which showed the incidence rate of Haismura in Examples 3 and 4 and Comparative Examples 3 and 4. It is a figure which shows an example of a general grinding | polishing apparatus. It is a figure which shows an example of the conventional index-type grinding | polishing apparatus. It is a flowchart which shows an example of the rotational movement method of each grinding | polishing axis | shaft of the conventional index type grinding | polishing method. It is the figure which showed the haze map of the 300 mm diameter wafer ground | polished by the conventional index-type grinding | polishing method. It is the figure which showed the haze map of the wafer of diameter 450mm grind | polished in the position of the 1st grinding | polishing axis | shaft by the grinding | polishing method of the conventional index method.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to this.
As described above, in the conventional index method wafer polishing method and polishing apparatus, the time until the start of the next step (wafer polishing restart, mounting, peeling) differs for each polishing axis, especially after polishing interruption In addition, there is a problem in that a haze is likely to occur in a polishing shaft that requires a long time movement after the polishing is completed.

Therefore, the present inventors conducted an experiment in order to obtain the time until the occurrence of haismura due to the etching action in the index-type wafer polishing method and polishing apparatus. Specifically, as shown in measurement 1 and measurement 2 in Table 1 and Table 2 below, the time from polishing interruption to restart and the time from the end of polishing to the start of the peeling operation are changed to confirm the occurrence of haismura. did. The object to be measured was the first polishing axis that is most prone to hazyness. That is, a case was included in which a 90-degree turning movement was included from the polishing interruption to the resumption, and a 270-degree turning movement was included after the polishing was completed until the peeling operation was started. Tables 1 and 2 show the time from the mounting of the wafer on the loading / unloading stage to the start of polishing on the first surface plate because the first polishing shaft is not etched by the abrasive. Not shown.

(Measurement 1)
As shown in Table 1, in measurement 1, the time from when the first polishing axis interrupts polishing on the first surface plate to when polishing resumes on the second surface plate averages 5.05 seconds, The average time from the interruption of polishing on the surface plate 2 to the resumption of polishing on the third surface plate is 5.10 seconds, and the polishing is finished on the third surface plate and then peeled off at the loading / unloading stage. Polishing was performed twice with an average time to start operation of 14.70 seconds. At this time, no haze was generated on the polished surface of the wafer polished by the first polishing shaft. Incidentally, LD / UL in Table 1 represents a loading / unloading stage.

(Measurement 2)
As shown in Table 2, in measurement 2, the time from when the first polishing axis interrupts polishing on the first surface plate to when polishing resumes on the second surface plate is 5.47 seconds on average. The average time from the interruption of polishing on the surface plate 2 to the restart of polishing on the third surface plate is 5.53 seconds. After the polishing is completed on the third surface plate, peeling is performed at the loading / unloading stage. Polishing was performed twice with an average time to start operation of 16.15 seconds. At this time, haismism was generated on the polished surface of the wafer polished by the first polishing shaft. Incidentally, LD / UL in Table 2 represents a loading / unloading stage.

From the results of measurement 1 and measurement 2 above, the present inventors have found that if the time during which the wafer is subjected to the etching action exceeds 15 seconds, haismism occurs. Then, the time from the interruption of the polishing of the wafer when switching the surface plate to the resumption of polishing and the time from the completion of the polishing of the wafer to the start of the peeling operation from the polishing head within 15 seconds can reduce the occurrence of haismura. The present invention was completed by conceiving that it can be effectively prevented.

First, the index type polishing apparatus of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the polishing apparatus 1 of the present invention includes a first surface plate 3, a second surface plate 4, and a third surface plate to which a polishing cloth 16 for polishing a wafer W is attached. A board 5 and a loading / unloading stage 2 for loading (mounting) and unloading (peeling) the wafer W onto the polishing head are provided. The first surface plate 3, the second surface plate 4, the third surface plate 5 and the loading / unloading stage 2 are arranged concentrically around the central axis 14.

Further, the polishing apparatus 1 has a first polishing shaft 10 for attaching and rotating a first polishing head 6 for holding the wafer W above the loading / unloading stage 2. Similarly, the fourth polishing head 9 and the fourth polishing shaft 13 are above the first surface plate 3, and the third polishing head 8 and the third polishing shaft 12 are above the second surface plate 4. A second polishing head 7 and a second polishing shaft 11 are provided above the third surface plate 5.

The respective rotating shafts are simultaneously turned around the central axis 14 so that the respective polishing heads are turned and perform polishing while switching the surface plate used for wafer polishing. The positions of the polishing heads and the polishing shaft shown in FIG. 1 are initial positions, and thereafter, the wafer is polished, loaded, and unloaded while switching the surface plate by repeating the swivel movement. As shown in FIG. 2, an abrasive supply mechanism 15 for supplying an abrasive onto the surface plate when polishing the wafer W is installed above each surface plate.

Here, the index-type polishing apparatus of the present invention is the time from the interruption of the polishing of the wafer W when switching the surface plate to the restart of polishing, and from the end of the polishing of the wafer W to the start of the peeling operation from the polishing head. The time is within 15 seconds. For example, the rotational movement speed of each polishing shaft and polishing head, the operation speed when the polishing head is raised or lowered above the surface plate, the polishing recipe (the polishing processing conditions such as pressure and time for pressing the wafer against the polishing cloth), What is necessary is just to set it as the polishing apparatus designed so that the time from the polishing interruption to the polishing restart and the time from the polishing end to the start of the peeling operation may be within 15 seconds.

With such a polishing apparatus, it is possible to shorten the time from the interruption of polishing to the restart of polishing and the time from the end of polishing to the start of the peeling operation, and the time for the polishing surface of the wafer W to be etched by the abrasive. Can be shortened. As a result, it is possible to prevent part of or the entire pattern of the foam of the abrasive from remaining on the polished surface of the wafer by the etching action of the abrasive attached to the polished surface of the wafer. It becomes.

FIG. 1 is an example of an index type polishing apparatus according to the present invention, and the present invention is not limited to this. The polishing apparatus of FIG. 1 includes three surface plates and four polishing heads, but the present invention is not limited to this number, and is an index type polishing apparatus that simultaneously polishes a wafer using a plurality of these. I need it. Moreover, it is good also as a polishing apparatus provided with two or more polishing heads allocated to one surface plate as shown in FIG.

Next, the index type wafer polishing method of the present invention when the polishing apparatus 1 of FIGS. 1 and 2 is used will be described.
As shown in FIGS. 1 and 3, first, the first polishing shaft 10 at the loading / unloading stage 2 position is rotated 90 degrees after loading the wafer onto the first polishing head 6. To the surface plate 3, and polishing is started there. Next, the polishing on the first surface plate 3 is interrupted, turned 90 degrees, moved to the second surface plate 4, and the polishing is resumed. Next, the polishing on the second surface plate 4 is interrupted, turned 90 degrees, moved to the third surface plate 5, and the polishing is resumed on the third surface plate 5.

When the polishing of the wafer is completed on the third surface plate 5, the wafer is turned to the opposite side of 270 degrees, moved to the loading / unloading stage 2, the wafer is unloaded, and one cycle is completed. The other polishing shafts simultaneously rotate in the same manner to perform polishing, loading, and unloading of the wafer while switching each surface plate or each surface plate and the loading / unloading stage 2.

Here, in the present invention, the time from the interruption of the polishing of the wafer W when switching the respective surface plates to the resumption of polishing and the time from the completion of the polishing of the wafer to the start of the peeling operation from the polishing head are within 15 seconds. .

Thus, by shortening the time from the interruption of polishing to the resumption of polishing and the time from the end of polishing to the start of the peeling operation, the time for etching the polished surface of the wafer with the abrasive can be shortened. As a result, it is possible to prevent a part or the whole of the foam pattern of the abrasive from remaining on the wafer polished surface by the etching action of the abrasive attached to the polished surface of the wafer, so that the process proceeds to the next step before the occurrence of haze. Can be effectively prevented from occurring.

In the above polishing method, a polishing apparatus provided with three surface plates and four polishing heads is used. However, the present invention is not limited to this number, and an index method of polishing a wafer simultaneously using a plurality of these. The present invention can be implemented using any polishing apparatus. Further, the present invention can be implemented even when a plurality of polishing heads assigned to one surface plate as shown in FIG. 1 are used instead of one.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these.

Example 1
A silicon wafer was polished according to the index-type wafer polishing method of the present invention using the index-type wafer polishing apparatus of the present invention as shown in FIGS. The wafer to be polished was 300 mm in diameter. In Example 1, a silicon wafer that has been polished using the first polishing axis that is most likely to generate a haze is measured with a particle measuring instrument SP3 manufactured by KLA-Tencor, and a haze map is automatically scaled. After output, it was judged visually.
In Example 1, the turning time of 270 degrees was performed, and the time to move to the next step was 10 seconds. This is the time from the end of wafer polishing to the start of the peeling operation for the first polishing axis. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than the case where it is included, it is 10 seconds or less.
FIG. 4 is a graph showing the incidence of haismura. As shown in FIG. 4, no haismura occurred.

(Example 2)
Same as Example 1 except that the time to move to the next step after turning at 270 degrees (in the first polishing axis, the time from the end of wafer polishing to the start of the peeling operation) was 15 seconds. The wafer was polished under various conditions, and the presence or absence of haismura was confirmed. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than when it is included, it is 15 seconds or less.
As shown in FIG. 4, no haismura occurred.

(Comparative Example 1)
Same as Example 1 except that the time required to move to the next step after turning at 270 degrees (in the first polishing axis, the time from the end of wafer polishing to the start of the peeling operation) was 20 seconds. The wafer was polished under various conditions, and the presence or absence of haismura was confirmed. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than when it is included, it is 20 seconds or less.
As shown in FIG. 4, the occurrence rate of haismura was a little less than 10%, and the occurrence of haismura could not be prevented.

(Comparative Example 2)
Same as Example 1 except that the time required to move to the next step after turning at 270 degrees (in the first polishing axis, the time from the end of the wafer polishing to the start of the peeling operation) was set to 30 seconds. The wafer was polished under various conditions, and the haze was evaluated. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than when it is included, it is 30 seconds or less.
As shown in FIG. 4, the occurrence rate of haismura was 25%, and the occurrence of haismura could not be prevented.

Example 3
The etching power by the abrasive varies depending on the amount of alkali component contained in the abrasive. Therefore, in Example 3, a wafer having a diameter of 300 mm is polished in a state in which haismura is more likely to occur by adding a 10% concentration potassium hydroxide solution to the abrasive used to increase the etching power of the abrasive. The presence or absence of Heismura was confirmed.
At this time, the turning movement of 270 degrees was performed, and the time to move to the next step was set to 15 seconds. This is the time from the end of wafer polishing to the start of the peeling operation for the first polishing axis. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than when it is included, it is 15 seconds or less. The concentration of the added potassium hydroxide in the abrasive was adjusted to 0.1%. And the presence or absence of haismura was confirmed by the method similar to Example 1. FIG. 5 is a graph which shows the incidence rate of haismura. As shown in FIG. 5, no haismura occurred.

Example 4
The wafer was polished under the same conditions as in Example 3 except that the concentration of potassium hydroxide in the abrasive was adjusted to 0.3%, and the haze was evaluated.
As shown in FIG. 5, no haismura occurred.

(Comparative Example 3)
Same as Example 3 except that the time required to move to the next step after turning at 270 degrees (in the first polishing axis, the time from the end of wafer polishing to the start of the peeling operation) was 20 seconds. The wafer was polished under various conditions, and the haze was evaluated. At this time, the time for moving to the next step after performing 90 degrees of swivel movement (in the first polishing axis, the time from polishing interruption to restart when switching the surface plate) is 270 degrees of swivel movement. Since the turning movement time is shorter than when it is included, it is 20 seconds or less.
As shown in FIG. 5, the incidence of haismura was 13%.

(Comparative Example 4)
The wafer was polished under the same conditions as in Comparative Example 3 except that the concentration of potassium hydroxide in the abrasive was adjusted to 0.3%, and the haze was evaluated.
As shown in FIG. 5, by increasing potassium hydroxide, the incidence of haismura increased to 31%.

As described above, from the results of Examples 1 and 2 and Comparative Examples 1 and 2, the time from polishing interruption to restart when switching the surface plate, and the time from the end of polishing to the start of the peeling operation should be within 15 seconds. As a result, it was found that the occurrence of haismura can be effectively prevented. Further, from the results of Examples 3 and 4 and Comparative Examples 3 and 4, even when a polishing agent having a stronger etching power is used, the time from polishing interruption to restart when switching the surface plate, and polishing It has been found that if the time from the end to the start of the peeling operation is within 15 seconds, the occurrence of haismura can be prevented.

Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Claims

A plurality of polishing heads for holding a wafer, a plurality of surface plates to which a polishing cloth for polishing the wafer is attached, and mounting of the wafer to the polishing head or peeling from the polishing head is performed. Preparing a loading / unloading stage for the polishing, arranging the plurality of surface plates and the loading / unloading stage concentrically, and rotating the polishing head to polish the wafer held by the polishing head An index method of polishing a plurality of wafers simultaneously while switching the platen used for
The time from the interruption of polishing of the wafer when switching the surface plate to the resumption of polishing and the time from the end of polishing of the wafer to the start of the peeling operation from the polishing head are within 15 seconds, Wafer polishing method.
A plurality of polishing heads for holding a wafer, a plurality of surface plates to which a polishing cloth for polishing the wafer is attached, and mounting of the wafer to the polishing head or peeling from the polishing head is performed. A plurality of surface plates and the loading / unloading stages are arranged concentrically, and the wafer held by the polishing head is polished by rotating the polishing head. An index type polishing apparatus for simultaneously polishing a plurality of wafers while switching the platen used for
The time from the interruption of polishing of the wafer when switching the surface plate to the restart of polishing and the time from the end of polishing of the wafer to the start of the peeling operation from the polishing head are within 15 seconds. A wafer polishing apparatus.