JP7305178B2 - Polishing equipment - Google Patents

Description

The present invention relates to a polishing apparatus.

Japanese Laid-Open Patent Publication No. 2002-100002 discloses a polishing apparatus that detects the protrusion of a wafer using a photoelectric sensor.

Patent No. 3761673

In a polishing apparatus that holds a wafer by a head, the wafer may slip out of the head (slip-out) when the wafer is released from the holding for some reason. If a slip-out occurs, it may lead to damage to various parts and wafers that make up the apparatus, so it is necessary to detect the slip-out.

However, when the photoelectric sensor is used, it detects the fluid present on the polishing pad, so there is a risk of erroneously detecting that slip-out has occurred even though slip-out has not occurred.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polishing apparatus capable of reducing erroneous detection and accurately detecting slip-out.

In order to solve the above-described problems, the polishing head according to the present invention includes, for example, a polishing head provided with a polishing pad on its upper surface and a surface plate provided rotatably in a first direction; A polishing head for polishing the wafer by pressing the surface of the wafer against a pad, the polishing head being rotatable in the first direction, and a slip-out detecting the protrusion of the wafer from the polishing head. a slip-out sensor, which is a capacitive proximity sensor, and the slip-out sensor is positioned outside the polishing head and adjacent to the outer peripheral surface of the polishing head, the surface plate is provided on the downstream side in the direction of rotation of the

According to the polishing head of the present invention, the slip-out sensor for detecting the protrusion of the wafer from the polishing head is a capacitive proximity sensor located outside the polishing head and adjacent to the outer peripheral surface of the polishing head. It is provided on the downstream side in the rotation direction of the surface plate. As a result, erroneous detection can be reduced and slip-out can be detected with high accuracy.

Here, the polishing head has a first polishing head and a second polishing head, and the slip-out sensor has a first slip-out sensor and a second slip-out sensor adjacent to the first polishing head. The first slip-out sensor is provided at the first polishing head, and the second slip-out sensor is provided adjacent to the second polishing head. Further, the second polishing head and the second slip-out sensor may be arranged at point-symmetrical positions with respect to the center of the platen. Thereby, the two slip-out sensors can be arranged under the same conditions, and the detection accuracies of the two slip-out sensors can be substantially matched.

Here, in plan view, the centers of the first polishing head and the second polishing head overlap with a first circle centered on the center of the surface plate, and in plan view, the first slip-out sensor The second slip-out sensor is arranged tangent to the first circle at the center of the first polishing head, and in plan view, the second slip-out sensor is arranged tangent to the first circle at the center of the second polishing head. may be This makes it easier to detect wafer slip-out.

Here, in plan view, the centers of the first polishing head and the second polishing head overlap with a first circle centered on the center of the surface plate, and in plan view, the first slip-out sensor and the second polishing head overlap each other. Two slip-out sensors may be arranged on the first circle. This makes it easier to detect wafer slip-out.

Here, the polishing head has a misplacement prevention sensor that detects whether or not the wafer is on the polishing pad, the misplacement prevention sensor is a capacitive proximity sensor, and the slip-out sensor and the slip-out sensor and the misplacement prevention sensor may be arranged at different distances from the surface of the polishing head facing the surface plate. This allows detection not only of slip-outs, but also of whether the wafer is on the polishing pad (ie misplaced).

According to the present invention, erroneous detection can be reduced and slip-out can be detected with high accuracy.

1 is a perspective view showing an outline of a polishing apparatus 1; FIG. 2 is a cross-sectional view showing an outline of a polishing head 10 and a surface plate 20; FIG. FIG. 2 is a side view schematically showing a polishing head 10 and a slip-out sensor 15; 2 is a perspective view showing an outline of a polishing head 10, a slip-out sensor 15 and a surface plate 20; FIG. 2 is a plan view showing an outline of a polishing head 10, a slip-out sensor 15 and a surface plate 20; FIG. 2 is a plan view schematically showing a polishing head 10, a slip-out sensor 15, and a platen 20 in the polishing apparatus 2; FIG. 3 is a side view schematically showing the polishing head 10, the slip-out sensor 15, and the misplacement prevention sensor 16 in the polishing apparatus 3. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is, for example, a polishing apparatus that polishes a wafer (substrate) by chemical mechanical polishing, so-called CMP (Chemical Mechanical Polishing) technology. In chemical-mechanical polishing, the surface of the wafer is mechanically scraped, and at the same time, the polishing solution chemically reacts with the surface of the wafer to perform polishing. Wafers of the present invention include wafers made of various materials such as silicon wafers, GaN (gallium nitride) SiC (silicon carbide) wafers, GaAs (gallium arsenide) wafers, and GaP (gallium phosphide) wafers. Note that CMP is just an example, and the present invention may be, for example, a polishing apparatus that polishes a wafer by a normal polishing method.

<First embodiment>
FIG. 1 is a perspective view showing an outline of a polishing apparatus 1. FIG. The polishing apparatus 1 mainly has a polishing head 10 that holds the back surface of a wafer W (not shown in FIG. 1), a platen 20 and a slurry supply section 30 .

A polishing pad 21 for polishing the wafer W is provided on the upper surface of the platen 20 . The slurry supply unit 30 supplies slurry (polishing liquid containing abrasive particles) onto the polishing pad 21 and rotates together with the surface plate 20 .

The polishing apparatus 1 has four surface plates 20 . Also, two polishing heads 10 and a slurry supply section 30 are provided for one surface plate 20 . The number of surface plates 20 included in the polishing apparatus 1 is not limited to four, and the number of polishing heads 10 and slurry supply units 30 provided for one surface plate 20 is not limited to two. .

The polishing head 10 and the platen 20 are rotatable clockwise or counterclockwise. In this embodiment, the polishing head 10 and the platen 20 rotate counterclockwise in plan view (see the arrow in FIG. 1).

FIG. 2 is a cross-sectional view showing an outline of the polishing head 10 and the surface plate 20. As shown in FIG. The polishing head 10 mainly includes a head main body 11, a retainer ring 12, a chuck plate 13, a backing material 14, and a slip-out sensor 15 (see FIG. 3).

An air chamber 11 a is provided inside the head body portion 11 . Compressed air is supplied to the air chamber 11a from an air supply source (not shown). The compressed air presses the entire surface of the wafer W uniformly because the compressed air stays in the air chamber 11a.

The retainer ring 12 is a substantially annular member provided below the head body portion 11 . A hollow portion of the retainer ring 12 is a recess 12a in which the backing material 14 and the wafer W are accommodated.

The chuck plate 13 is a substantially disc-shaped plate-like portion made of metal (for example, stainless steel) or ceramic, and contacts the surface of the backing material 14 that the wafer W does not contact.

The backing material 14 is a substantially disk-shaped thin film (sheet-like) member having flexibility and elasticity. The backing material 14 is in contact with the lower side (surface plate 20 side) of the chuck plate 13, and is provided inside the recess 12a. For the backing material 14, for example, suede or a polyurethane foam sheet can be used. The thickness of the backing material 14 is minutely changed by pressurization. The backing material 14 is formed by thinly slicing a foamed polyurethane sheet, for example, and has a large number of minute cavities on its surface. When water is applied to the surface of the backing material 14 and the wafer W is pressed against the backing material 14 , the wafer W is pressed against the backing material 14 by the negative pressure generated when the water in the cavity is discharged to the outside and the surface tension of the water. Fixed.

In the polishing apparatus 1, while rotating the surface plate 20 to which the polishing pad 21 is adhered, slurry is supplied onto the polishing pad 21, and the wafer W held by the polishing head 10 is rotated, the wafer W is placed on the polishing pad 21. By pressing the surface of the wafer W, the insulating film and the metal film layer formed on the surface of the wafer W are polished.

Next, the slip-out sensor 15 will be explained. FIG. 3 is a side view schematically showing the polishing head 10 and the slip-out sensor 15. FIG.

The slip-out sensor 15 is a sensor that detects the slip-out of the wafer W from the polishing head 10 . A capacitive proximity sensor is used as the slip-out sensor 15 .

A slip-out sensor 15 is provided adjacent to the outer peripheral surface of the polishing head 10 . The tip of the slip-out sensor 15 is provided so as not to protrude from the lower surface 12b (the surface facing the platen 20) of the polishing head 10 (here, the retainer ring 12). In this embodiment, the thickness of the retainer ring 12 is approximately 20 mm, and the distance h1 between the slip-out sensor 15 and the surface 12b is approximately 5 mm to approximately 8 mm. Note that the distance h1 changes depending on the type of the slip-out sensor 15 and the like.

FIG. 4 is a perspective view showing an outline of the polishing head 10, the slip-out sensor 15 and the platen 20. FIG. In FIG. 4, illustration of the slurry supply unit 30 is omitted.

The polishing head 10 has a polishing head 10A and a polishing head 10B, and the slip-out sensor 15 has a slip-out sensor 15A and a slip-out sensor 15B. A slip-out sensor 15A is provided adjacent to the polishing head 10A, and a slip-out sensor 15B is provided adjacent to the polishing head 10B.

The slip-out sensor 15A is fixed to the housing 31 of the polishing apparatus 1 by a mounting member 17A. Moreover, the slip-out sensor 15B is fixed to the housing 31 by a mounting member 17B. That is, even if the polishing heads 10A and 10B rotate, the slip-out sensors 15A and 15B do not rotate.

The slip-out sensors 15A and 15B are provided outside the polishing heads 10A and 10B and adjacent to the outer peripheral surfaces of the polishing heads 10A and 10B, respectively. Moreover, the slip-out sensors 15A and 15B are provided on the downstream side of the surface plate 20 in the rotational direction. Since the surface plate 20 rotates counterclockwise, the slip-out sensor 15A is provided behind the polishing head 10A in FIG. It is located on the front side.

When the wafer W pops out of the polishing head 10 , it pops out to the downstream side in the rotation direction of the surface plate 20 along with the rotation of the surface plate 20 . Therefore, the slip-out sensors 15A and 15B are provided on the downstream side of the polishing heads 10A and 10B in the rotation direction of the surface plate 20 .

FIG. 5 is a plan view schematically showing the polishing head 10, the slip-out sensor 15 and the platen 20. FIG. The polishing heads 10A and 10B are arranged so that the centers axA and axB of the polishing heads 10A and 10B overlap a circle S centered at the center 20ax of the platen 20 in plan view.

The slip-out sensors 15A and 15B are provided on the downstream side of the surface plate 20 in the rotational direction. Since the surface plate 20 rotates counterclockwise, in the plan view shown in FIG. 5, a line (line L ) corresponds to the downstream side in the rotation direction of the surface plate 20, and a line (line L) passing through the center 20ax of the surface plate 20 and the center axB of the polishing head 10B in the circle indicating the polishing head 10B. The lower semicircular portion corresponds to the downstream side of the surface plate 20 in the rotation direction.

Further, the slip-out sensor 15A is arranged on the tangent line TA of the circle S at the center axA of the polishing head 10A in plan view. Further, the slip-out sensor 15B is arranged on the tangent line TB of the circle S at the center axB of the polishing head 10B in plan view. Since the wafer W tends to jump out of the polishing head 10 along the tangent lines TA and TB, slip-out of the wafer W can be easily detected by providing the slip-out sensors 15A and 15B on the tangent lines TA and TB, respectively.

Also, the polishing head 10A and the slip-out sensor 15A, and the polishing head 10B and the slip-out sensor 15B are arranged at point-symmetrical positions with respect to the center 20ax of the platen 20 in plan view. Thereby, the polishing head 10A and the slip-out sensor 15A and the polishing head 10B and the slip-out sensor 15B are arranged under the same conditions, and the detection accuracy of the slip-out sensor 15A and the detection accuracy of the slip-out sensor 15B are substantially equal. match.

According to the present embodiment, a capacitive proximity sensor is used as the slip-out sensor 15, and the position adjacent to the outer peripheral surface of the polishing head 10 outside the polishing head 10 and downstream in the rotation direction of the surface plate 20 is detected. By providing the slip-out sensor 15 at , erroneous detection can be prevented and the slip-out of the wafer W can be detected with high accuracy.

For example, when a photoelectric sensor is used as the slip-out sensor, the fluid is erroneously detected. Further, when the slip-out sensor is provided inside the polishing head, the fluid is erroneously detected due to the influence of disturbance. On the other hand, by using a capacitive proximity sensor as the slip-out sensor and providing the slip-out sensor outside the polishing head, it is possible to reduce the influence of disturbance and prevent erroneous detection. In particular, by making the supply amount of slurry and the number of rotations of the surface plate 20 constant and by stabilizing the flow of fluid, it is possible to further reduce the influence of disturbances.

Further, in the present embodiment, by providing the slip-out sensors 15A and 15B on the tangential lines TA and TB in plan view, it is possible to more reliably detect that the wafer W has jumped out of the polishing head 10 .

<Second Embodiment>
In the first embodiment of the present invention, the slip-out sensors 15A and 15B are arranged on the tangent lines TA and TB of the circle S at the centers axA and axB of the polishing heads 10A and 10B. The arrangement is not limited to this.

2nd Embodiment of this invention is a form which arrange|positions slip-out sensors 15A and 15B on the circle S. FIG. A polishing apparatus 2 according to the second embodiment will be described below. The same reference numerals are assigned to the same parts as in the first embodiment, and the description thereof is omitted.

FIG. 6 is a plan view schematically showing the polishing head 10, the slip-out sensor 15 and the platen 20 in the polishing apparatus 2. FIG. The polishing head 10 has a polishing head 10A and a polishing head 10B. The slip-out sensor 15 has a slip-out sensor 15A and a slip-out sensor 15B. A slip-out sensor 15A is provided adjacent to the polishing head 10A, and a slip-out sensor 15B is provided adjacent to the polishing head 10B. The slip-out sensors 15A and 15B are provided outside the polishing heads 10A and 10B and adjacent to the outer peripheral surfaces of the polishing heads 10A and 10B, respectively.

The polishing head 10A and the slip-out sensor 15A, and the polishing head 10B and the slip-out sensor 15B are arranged at point-symmetrical positions with respect to the center 20ax of the platen 20 in plan view.

The slip-out sensors 15A and 15B are provided on the downstream side of the surface plate 20 in the rotational direction. Since the surface plate 20 rotates counterclockwise, in the plan view shown in FIG. 6, the semicircular portion above the line L corresponds to the downstream side of the surface plate 20 in the rotation direction. As for the polishing head 10B, the semicircular portion below the line L corresponds to the downstream side of the surface plate 20 in the rotation direction. Also, the slip-out sensors 15A and 15B are arranged on a circle S in plan view. Depending on the rotational speed of the platen 20, the wafer W tends to pop out of the polishing head 10 along the circle S. Therefore, by providing the slip-out sensors 15A and 15B on the circle S, the slip-out of the wafer W can be easily detected. Become.

<Third Embodiment>
A third embodiment of the present invention further includes a misplacement prevention sensor. A polishing apparatus 3 according to the third embodiment will be described below. The same reference numerals are assigned to the same parts as in the first embodiment, and the description thereof is omitted.

FIG. 7 is a side view schematically showing the polishing head 10, the slip-out sensor 15, and the misplacement prevention sensor 16 in the polishing apparatus 3. FIG. A slip-out sensor 15 and a misplacement prevention sensor 16 are provided adjacent to the polishing head 10 .

The misplacement prevention sensor 16 is a sensor that detects whether or not the wafer W is on the polishing pad 21 . The case where the wafer W is on the polishing pad 21 is, for example, the case where the wafer W is left on the polishing pad 21 without being taken out after polishing. Like the slip-out sensor 15, the misplacement prevention sensor 16 is a capacitive proximity sensor.

The slip-out sensor 15 and the misplacement prevention sensor 16 are provided adjacent to the outer peripheral surface of the polishing head 10 . Further, the slip-out sensor 15 and the misplacement prevention sensor 16 are provided so that their tips do not protrude from the surface 12b.

Further, the slip-out sensor 15 and the misplacement prevention sensor 16 are different in distance from the surface (surface 12b) facing the surface plate 20 of the polishing head 10 . The distance h1 between the slip-out sensor 15 and the surface 12b is about 5 mm to about 8 mm, and the distance h2 between the misplacement prevention sensor 16 and the surface 12b is smaller than the distance h1 between the slip-out sensor 15 and the surface 12b.

According to the present embodiment, it is possible to detect whether or not the wafer W is on the polishing pad 21 as well as the slip-out.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and design changes and the like are also included within the scope of the gist of the present invention. .

In addition, in the present invention, the term "substantially" is not limited to the case of being exactly the same, but is a concept that includes errors and deformations to the extent that the identity is not lost. For example, "substantially parallel" is not limited to being strictly parallel. Further, for example, the substantially rectangular shape is not limited to a strictly rectangular shape. Further, for example, when simply expressing parallel, orthogonal, identical, etc., not only strictly parallel, orthogonal, identical, etc., but also approximately parallel, approximately orthogonal, approximately identical, etc. are included.

1, 2, 3: polishing apparatus 10, 10A, 10B: polishing head 11: head body 11a: air chamber 12: retainer ring 12a: recess 12b: surface 13: chuck plate 14: backing material 15, 15A, 15B: slip Out sensor 16: Misplacement prevention sensor 17A, 17B: Mounting member 20: Surface plate 21: Polishing pad 30: Slurry supply unit 31: Housing

Claims (4)

a surface plate provided with a polishing pad on its upper surface and provided rotatably in a first direction;
a polishing head for polishing the wafer by pressing the front surface of the wafer against the polishing pad while holding the rear surface of the wafer, the polishing head being rotatable in the first direction;
a slip-out sensor that detects the protrusion of the wafer from the polishing head, the slip-out sensor being a capacitive proximity sensor;
with
The slip-out sensor is provided outside the polishing head and at a position adjacent to the outer peripheral surface of the polishing head on the downstream side in the rotation direction of the surface plate ,
The polishing head has a first polishing head and a second polishing head,
The slip-out sensor has a first slip-out sensor and a second slip-out sensor,
The first slip-out sensor is provided adjacent to the first polishing head, and the second slip-out sensor is provided adjacent to the second polishing head,
In a plan view, the first polishing head and the first slip-out sensor, and the second polishing head and the second slip-out sensor are arranged at point-symmetrical positions with respect to the center of the platen.
A polishing apparatus characterized by: In plan view, the centers of the first polishing head and the second polishing head overlap with a first circle centered on the center of the surface plate,
In plan view, the first slip-out sensor is arranged on a tangent line of the first circle at the center of the first polishing head,
2. The polishing apparatus according to claim 1 , wherein the second slip-out sensor is arranged on a tangent line of the first circle at the center of the second polishing head in plan view. In plan view, the centers of the first polishing head and the second polishing head overlap with a first circle centered on the center of the surface plate,
The polishing apparatus according to claim 1 , wherein the first slip-out sensor and the second slip-out sensor are arranged on the first circle in plan view. the polishing head has a misplacement prevention sensor that detects whether the wafer is on the polishing pad;
The misplacement prevention sensor is a capacitive proximity sensor and is provided adjacent to the slip-out sensor,
4. The method according to any one of claims 1 to 3 , wherein the slip-out sensor and the misplacement prevention sensor are arranged at different distances from the surface of the polishing head facing the surface plate. polishing equipment.

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