This application is based on Japanese patent application No. 2009-108192 the content of which is incorporated hereinto by reference.
1. Technical Field
The present invention relates to a polishing apparatus and a polishing method.
2. Related Art
Polishing of a polished surface of a wafer is carried out in, for example, a CMP (Chemical Mechanical Polish) step of a semiconductor manufacturing process using CMP polishing apparatus.
Polishing apparatus illustrated in
Polishing apparatus illustrated in
Polishing apparatus illustrated in
However, with the polishing apparatus of Japanese Laid-Open patent publication No. H9-254018 (
In Japanese Laid-Open Patent Publication No. 2000-263417, washing is carried out mainly while carrying out conditioning with the brush 306 in contact with the polishing pad 302 with the structures for either of
It is therefore extremely difficult to achieve a situation where both the time required to move the conditioning disc in order that the conditioning disc is washed or wetted is made short and the occurrence of scratches on a subject of polishing such as a wafer is sufficiently suppressed.
According to the present invention, there is provided a polishing apparatus comprising a polishing table with a polishing pad on an upper surface, a support unit supporting a subject of polishing while polishing the subject of polishing so that the subject of polishing comes into contact with the polishing pad, a conditioning disc carrying out conditioning of said polishing pad, a moving mechanism moving the conditioning disc towards a standby position above the polishing pad, and a spraying mechanism spraying liquid to the conditioning disc positioned at the standby position so as to wash or wet the conditioning disc.
According to the present invention, it is possible to wash or wet the conditioning disc, and it is possible to suppress slurry from becoming affixed to the conditioning disc. It is therefore possible to suppress the occurrence of scratches at the wafer caused by the falling of fixed matter.
It is also possible to spray liquid to the conditioning disc with the conditioning disc moved to the standby position above the polishing pad and to wash or wet the conditioning disc. It is also therefore possible to dramatically reduce the time required to move the conditioning disc in order to wash or wet the conditioning disc compared to the case of moving the conditioning disc to the side of the polishing table to a position lower than the upper surface of the polishing table every time the conditioning disc is washed or wetted (Japanese Laid-Open patent publication No. H9-254018). A point of difference with the structure where a brush comes into contact with the polishing pad and washing is then carried out during the conditioning operation (Japanese Laid-Open Patent Publication No. 2000-263417.) is that when fixed matter in the slurry becomes affixed to the conditioning disc, this fixed matter is swept away to the side of the subject of polishing by the conditioning disc while liquid is sprayed by the spraying mechanism and the problem where scratches occur on the subject of polishing is therefore avoided. It is therefore possible to sufficiently suppress the occurrence of scratches on the subject of polishing.
It is therefore also possible to achieve a situation where both the time required to move the conditioning disc in order that the conditioning disc is washed or wetted is made short and the occurrence of scratches on a subject of polishing such as a wafer is sufficiently suppressed.
According to the present invention, there is also provided a polishing method comprising: bringing a subject of polishing into contact with a polishing pad provided on an upper surface of a polishing table so as to polish said subject of polishing, conditioning the polishing pad using a conditioning disc, moving the conditioning disc to a standby position above the polishing pad, and spraying liquid to the conditioning disc positioned at the standby position so as to wash or wet the conditioning disc.
According to the present invention, it is therefore possible to achieve a situation where both the time required to move the conditioning disc for washing and wetting is made short and the occurrence of scratches on a subject of polishing such as a wafer is sufficiently suppressed.
The above and other objects, advantages and features of the present invention will be more apparent from the following description of certain preferred embodiments taken in conjunction with the accompanying drawings, in which:
Before describing of the present invention, the related art will be explained in detail with reference to
As shown in
Polishing of the wafer 104 is carried out by dripping slurry discharged by the slurry nozzle 106 onto the polishing pad 101 and then rotating a wafer 104 about the polishing head 103 in this state where a surface of the wafer 104 supported by the polishing head 103 that is to be polished presses against the polishing pad 101.
As the polishing advances, polishing waste (waste cut away from the wafer 104, the polishing pad 101, and the retainer ring 105) or aggregate of the slurry etc. clogs up grooves or holes formed on the polishing pad 101 or pores in the material itself constituting the polishing pad 101. And the surface of the polishing pad 101 then becomes smoother as the polishing progresses. The polishing rate therefore falls as the polishing advances as a result of the polishing pad 101 becoming clogged up and the surface of the polishing pad 101 becoming smoother.
Conditioning (so-called “sharpening”) of the polishing pad 101 can be carried out in order to suppress falls in the polishing rate using the conditioning disc 107 which typically has a diamond abrasive grain fitted. The conditioning disc 107 can be referred to as a “conditioner”.
Carrying out conditioning between polishing of one wafer 104 and polishing off the next wafer 104 is referred to as “ex-situ conditioning”. Performing conditioning in parallel with the polishing in order to not lower the processing efficiency of the CMP polishing apparatus 100 is referred to as “in-situ conditioning”.
However, the slurry contains abrasive grain such as silica. This abrasive grain therefore becomes a fixed to the conditioning disc 107. When this fixed matter then comes away from the conditioning disc 107 and falls onto the polishing pad 101, this causes scratches (polishing blemishes) to occur on the wafer 104.
The technology for taking these problems into account is the technology of, for example, Japanese Laid-Open Patent Publications No. H9-254018 and No. 2000-263417. However, it is extremely difficult with the technology of Japanese Laid-Open Patent Publications No. H9-254018 and No. 2000-263417 to achieve a situation where both the time required to move the conditioning disc in order that the conditioning disc is washed or wetted is made short and the occurrence of scratches on a subject of polishing such as a wafer is sufficiently suppressed.
The invention will be now described herein with reference to illustrative embodiments. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the invention is not limited to the embodiments illustrated for explanatory purposes.
Embodiments of the present invention will be explained below, referring to the attached drawings. Note that any similar constituents will be given the same reference numerals or symbols in all drawings, and explanations therefor will not be repeated.
[First Embodiment]
The polishing apparatus (for example, the CMP polishing apparatus 1) of this embodiment includes a polishing table 3 with a polishing pad 2 on an upper surface, a support unit (polishing head 7) for supporting the subject of polishing while polishing the subject of polishing (for example, wafer 9) so that the subject of polishing comes into contact with the polishing pad 2, a conditioning disc 4 for carrying out to conditioning of the polishing pad 2, a moving mechanism (including, for example, a swing arm 5, a conditioning disc swing actuator 21, and a conditioning disc lifting and lowering actuator 22) capable of moving the conditioning disc 4 to a standby position W above the polishing pad 2, and a injection mechanism (including, for example, a washing water nozzle 6 and a washing water supply actuator 27) for injecting liquid (for example, washing water) to the conditioning disc 4 positioned at the standby position W, for washing or wetting the conditioning disc 4. A polishing method of this embodiment is provided with bringing the subject of polishing (for example, the wafer 9) into contact with the polishing pad 2 provided on the upper surface of the polishing table 3 so as to polish the subject of polishing, conditioning the polishing pad 2 using the conditioning disc 4, moving the conditioning disc 4 to a standby position W above the polishing pad 2, and spraying a liquid (for example, washing water) to the conditioning disc 4 positioned at the standby position W so as to wash or wet the conditioning disc 4. A detailed explanation is provided below.
First, an explanation is given of the configuration of the CMP polishing apparatus 1.
As shown in
The polishing head 7 has a retainer ring 10 that supports the wafer 9 at a lower surface. The slurry nozzle 8 discharges slurry onto the polishing pad 2.
The conditioning disc 4 is for conditioning (so-called sharpening) the polishing pad 2.
The swing arm 5 supports the conditioning disc 4 at a tip thereof. By swinging in a direction along arrow A of
The swing arm 5 is also capable of lifting and lowering the conditioning disc 4 in the direction of arrow B of
The swing arm 5 is, for example, also capable of rotating the conditioning disc 4 in a plate-face direction (the direction of arrow C in
The washing water nozzle 6 is located at the side of the polishing table 3 close to the polishing table 3 and is also located at positioned close to the standby position W. As illustrated, for example, in
As shown, for example, in
Flying off of the washing water to the polishing area on the polishing pad 2 (the area where polishing of the wafer 9 supported by the polishing head 7) invites a lowering in the polishing rate. The direction of injection of the washing water is therefore set appropriately according to the standby position W of the conditioning disc 4. In the case of this embodiment, as shown in
Polishing of the wafer 9 by the polishing head 7 is preferably carried out for portions excluding the edge portions on the polishing table 3 (portions more towards the centre than the edge portions). The conditioning disc 4 is positioned above the polishing table 3 during washing. Therefore, the washing water falls onto the polishing table 3 from the conditioning disc 4 but the washing water only falls on the edge portions of the polishing table 3. This means that polishing of the wafer 9 at positions further towards the centre of the polishing table 3 than the edge portions of the polishing table 3 is not impaired.
As shown in
The operation is now described.
Polishing of the wafer 9 is carried out by bringing the polishing head 7 down so that the wafer 9 presses against the polishing pad 2 in a state where the wafer 9 is supported by a retainer ring 10 of the polishing head 7. Slurry is then dropped from the slurry nozzle 8 onto the polishing pad 2 and the polishing head 7 and the polishing table 3 are caused to rotate.
The conditioning operation of the polishing pad 2 by the conditioning disc 4 is carried out by lowering the conditioning disc 4 so as to press against the polishing pad 2 and rotating the conditioning disc 4. During the conditioning operation it is possible to carry out conditioning over the entire surface of the polishing pad 2 by moving the conditioning disc 4 along the direction of the arrow A of
Washing of the conditioning disc 4 is carried out by spraying washing water in the direction of the conditioning disc 4 from the washing water nozzle 6 in this state where the conditioning disc 4 is moved to the standby position W after the conditioning operation.
An example of specific timing for the conditioning operation and washing operation is described with reference to the timing charts of
For example, when the conditioning disc 4 is standing by in the standby position W only in the latter period of the polishing operation, as shown in
When standing by of the conditioning disc 4 is intermittently repeated during the polishing operation, the timing chart becomes as shown in
In the above, an explanation is given where washing water is sprayed by the spraying mechanism so as to wash the conditioning disc 4 but rather than washing the conditioning disc 4 with pressurized sprayed washing water, it is also possible to perform spraying (for example, spraying a mist) so as to wet (moisture) the conditioning disc 4.
According to the first embodiment, there is provided the polishing table 3 having the polishing pad 2 on an upper surface, the polishing head 7 supporting the wafer 9 during polishing so as to bring the wafer 9 into contact with the polishing pad 2, the conditioning disc 4 for conditioning the polishing pad 2, the swing arm 5 capable of moving the conditioning disc 4 to the standby position W above the polishing pad 2, and the washing water nozzle 6 that sprays the conditioning disc 4 positioned at the standby position W with washing water and washes or wets the conditioning disc 4. It is therefore possible to wash or wet the conditioning disc 4 and suppress the affixing of slurry to the conditioning disc 4. It is therefore possible to suppress the occurrence of scratches to the wafer 9 caused by the falling of fixed matter.
It is also possible to spray the conditioning disc 4 with a liquid so as to wash or wet the conditioning disc 4 in a state where the conditioning disc 4 is moved to the standby position W above the polishing pad 2. It is therefore possible to substantially reduce the time required to move the conditioning disc 4 in order to wash or wet the conditioning disc 4 compared to the case where the conditioning disc 4 is moved to the side of the polishing table 3 to the positioned below the upper surface of the polishing table 3 every time the conditioning disc 4 is washed or wetted (Japanese Laid-Open Patent Publication No. H9-254018).
Further, even if fixed matter of the slurry becomes affixed to the conditioning disc 4, this fixed matter will not swept away to the side of the wafer 9 by the conditioning disc 4 while washing water is being sprayed by the washing water nozzle 6, and the problem where scratches occur on the wafer 9 is avoided. It is therefore possible to sufficiently suppress the occurrence of scratches on the wafer 9.
This means that it is possible to both shorten the time required to move the conditioning disc 4 in order to wash or wet the conditioning disc 4 and sufficiently suppress the occurrence of scratches on the wafer 9.
The conditioning disc 4 is also in standby above the polishing table 3. This means that it is possible to suppress delays in starting the conditioning after washing or wetting the conditioning disc 4. Namely, it is possible to suppress delays in the conditioning operation even when, for example, the duty of the conditioning operation with respect to the polishing operation is high and the frequency with which the conditioning disc 4 is on standby is also high (for example, as shown in
The standby position W is above the edge portion of the polishing pad 2. It is therefore possible to keep the influence of the sprayed washing water on the polishing to a minimum.
The conditioning disc 4 positioned at the standby position W is rotated in the direction of the plate surface. It is therefore possible to wash or wet the entire surface of the conditioning disc 4 by spraying liquid only onto the portions of the conditioning disc 4 where the distance from the center of the polishing table 3 is equal to or longer than the distance between the center of the polishing table 3 and the center of the conditioning disc 4. It is therefore possible to make the influence of the sprayed washing water on the polishing extremely small.
The washing water nozzle 6 only sprays washing water. when the conditioning disc 4 is positioned at the standby position W. It is therefore possible to reduce waste of washing water and it is possible to reduce the amount of washing water that splashes onto the polishing pad 2.
Further, the washing water nozzle 6 is located to the side of the polishing table 3 and the washing water is sprayed at an incline upwards. This means that it is possible to spray washing water towards the conditioning disc 4 even if the washing water nozzle 6 is located so as not to interfere with the polishing table 3 and the polishing pad 2.
The configurations in both
[Second Embodiment]
In the first embodiment above, an explanation is given of an example where the whole of the conditioning disc 4 is positioned above the polishing pad 2 at the standby position W, as illustrated in
Specifically, for example, as illustrated in
According to the second embodiment, part of the conditioning disc 4 is positioned to the outside of the polishing pad 2 in the standby position W. It is therefore possible to keep the influence of the sprayed washing water on the polishing to a minimum. Further, it is also possible to make the influence of the sprayed washing water on the polishing dramatically smaller when the center of the conditioning disc 4 is positioned outside of the polishing pad 2 in the standby position W.
[Third Embodiment]
In the case of this embodiment, as shown in
The operation of the conditioning disc tilting actuator 29 tilting the conditioning disc 4 can be carried out when the conditioning disc 4 is positioned at the standby position W or when the conditioning disc 4 is in the middle of going (rising) to the standby position W. In the case of this embodiment, the conditioning disc 4 that is in a tilted state is, for example, rotated by the conditioning disc rotation actuator 23.
According to the third embodiment, a moving mechanism (constructed, for example, from the swing arm 5, the conditioning disc swing actuator 21, the conditioning disc lifting and lowering actuator 22, and the conditioning. disc tilting actuator 29) adjusts the posture of the conditioning disc 4 in the standby position W so that the lower surface of the conditioning disc 4 faces towards the lateral direction of the polishing table 3. It therefore becomes easier for washing water sprayed from the washing water nozzle 6 to collide with the conditioning disc 4 and washing or wetting of the conditioning disc 4 can be carried out in a more appropriate manner. It is therefore possible for the center position of the conditioning disc 4 to be further from the center of the polishing pad 2 than in the first embodiment and the influence of the sprayed washing water on polishing can be further reduced.
In each of the above embodiments, an explanation is given taking the CMP polishing apparatus 1 and 30 as the polishing apparatus but the present invention can also be applied to polishing apparatus other than CMP polishing apparatus. The subject of polishing can also be that other than the wafer 9. An explanation is also given where a spraying mechanism is exemplified by a washing water nozzle 6 and washing water is sprayed as a liquid but it is also possible to spray washing liquid other than water or to spray a wetting agent.
Number | Date | Country | Kind |
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2009-108192 | Apr 2009 | JP | national |
Number | Name | Date | Kind |
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5839947 | Kimura et al. | Nov 1998 | A |
6217430 | Koga et al. | Apr 2001 | B1 |
6358124 | Koga et al. | Mar 2002 | B1 |
6488573 | Kobayashi et al. | Dec 2002 | B1 |
6609962 | Nabeya et al. | Aug 2003 | B1 |
6634934 | Akaike | Oct 2003 | B1 |
7025663 | Kim | Apr 2006 | B2 |
Number | Date | Country |
---|---|---|
9-254017(A) | Sep 1997 | JP |
9-254018 | Sep 1997 | JP |
3708740 | Oct 2005 | JP |
Entry |
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Japanese Office Action dated Jun. 4, 2013 with partial English translation thereof. |
Number | Date | Country | |
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20100273401 A1 | Oct 2010 | US |