JP3614666B2 - Wafer polishing head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer polishing head used in an apparatus for polishing a semiconductor wafer surface in a semiconductor manufacturing process.
[0002]
[Prior art]
In recent years, the miniaturization of patterns due to the high integration of semiconductor manufacturing equipment has progressed. In particular, the surface of a semiconductor wafer during the manufacturing process is flattened as much as possible in order to easily and reliably form a fine pattern with a multilayer structure. It is becoming important. In that case, a chemical mechanical polishing method (CMP method) is in the spotlight from the viewpoint that the degree of planarization is high because the surface film is polished and the film can be embedded in the recess.
[0003]
The CMP method is a method of chemically and mechanically polishing and planarizing a wafer surface using an alkaline solution, an abrasive, or the like. As an example of a wafer polishing head used in this method, Japanese Patent Laid-Open No. Hei 8- No. -229804 describes what is shown in FIG.
[0004]
In FIG. 8, the wafer polishing head 50 includes a head body 53 including a top plate portion 51 and a cylindrical peripheral wall portion 52 fixed to the outer periphery of the top plate portion 51, and a rubber stretched inside the head body 53. A diaphragm 54 made of an elastic material such as, a pressure adjusting mechanism 56 for adjusting the pressure in the fluid chamber 58, a disk-like carrier 55 fixed to the lower surface of the diaphragm 54, and a concentric arrangement on the outer periphery of the carrier 55 And an annular retainer ring 57.
[0005]
The carrier 55 and the retainer ring 57 are respectively fixed to a carrier fixing ring 59 and a retainer ring fixing ring 62 provided on the upper surface of the diaphragm 54, and the retainer ring 57 is between the outer peripheral surface of the carrier 55 and the peripheral wall portion 52. Are arranged concentrically with a slight gap. Here, the reason why the gap is arranged with a slight gap is to prevent the movable range of the retainer ring 57 from becoming too large due to the elastic deformation of the diaphragm 54.
[0006]
At the time of wafer polishing, the wafer W is adhered to the wafer adhesion sheet S provided on the lower surface of the carrier 55 while the outer periphery is locked by the retainer ring 57. The surface of the wafer W is brought into contact with a polishing pad 63 affixed to the upper surface of the platen 61 and is polished by rotating the wafer polishing head 50 while supplying slurry containing a polishing abrasive.
[0007]
At this time, the carrier 55 and the retainer ring 57 have a floating structure that is independently displaced in the vertical direction by the elastic deformation of the diaphragm 54, and the pressure applied to the polishing pad 63 by the carrier 55 and the retainer ring 57. Is changed according to the pressure inside the fluid chamber 58 adjusted by the pressure adjusting mechanism 56.
[0008]
[Problems to be solved by the invention]
Such a wafer polishing head has a floating structure in which the carrier 55 and the retainer ring 57 are supported by the diaphragm 54. Therefore, depending on the movable range of the carrier 55 and the retainer ring 57, the inclination of the polishing pad 63, the axis inclination of each element, etc. Although the structure is absorbed, when the polishing pad 63 has a large inclination or when the axial inclination of each element is accumulated to become a large inclination as a whole, the movable range of the retainer ring 57 becomes small, that is, the peripheral wall. The clearance between the portion 52 and the retainer ring 57 becomes small and may interfere with the peripheral wall portion 52. At this time, the smooth displacement of the retainer ring 57 is hindered, and the inclination of each element is not sufficiently absorbed. As a result, the polishing state of the wafer W may be uneven.
[0009]
Further, when the finishing accuracy of each part of the wafer polishing head 50 is insufficient, or when a deviation occurs during assembly, the clearance between the peripheral wall portion 52 and the retainer ring 57 is not stably maintained, and thus the same interference occurs. Problems arise.
[0010]
On the other hand, if the clearance between the peripheral wall portion 52 and the retainer ring 57 is too large, the movable range of the retainer ring 57 becomes too large, and the wafer W is not stably locked to the retainer ring 57.
[0011]
The present invention has been made in view of such circumstances, and prevents wafers from interfering with the retainer ring and the peripheral wall portion, and can perform stable polishing without hindering smooth displacement of the retainer ring. The purpose is to provide a head.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, a wafer polishing head having the following configuration is employed in the present invention. That is, a wafer polishing head according to the present invention includes a head body composed of a top plate portion and a cylindrical peripheral wall portion provided below the outer periphery of the top plate portion, and a tension in the head body perpendicular to the head axis. A diaphragm, a pressure adjusting mechanism for adjusting a fluid pressure filled in a fluid chamber formed between the diaphragm and the head body, and a fixed to the diaphragm so as to be displaceable in the head axis direction together with the diaphragm. And is arranged concentrically between the carrier for holding one surface of the wafer to be polished, the inner wall of the peripheral wall portion and the outer periphery of the carrier, and is fixed to the diaphragm along with the diaphragm in the head axis direction. A wafer polishing head provided with a retainer ring provided so as to be displaceable and abutting against a polishing pad at the time of polishing. At a position spaced a retainer ring and the circumferential wall, at a position separated and said retainer ring and said peripheral wall portion, formed between the retainer ring is connected to said peripheral wall, and the even number around these two connecting portions Link means are provided at least at three places, absorbing the carrier, the inclination of the axis of the retainer ring, the vertical movement of the retainer ring, and the torsional motion, and preventing interference between the retainer ring and the peripheral wall portion. And
[0013]
According to the present invention, when the retainer ring and the peripheral wall portion of the head main body are connected at a position separated by the link means, the movable range of the retainer ring is reduced due to the axial inclination of each element. In addition, interference between the retainer ring and the peripheral wall can be prevented. At this time, since the smooth displacement of the retainer ring is not hindered, the wafer is stably locked.
[0014]
In addition, the link means forms a link mechanism having a pair of turns around the tangent of at least the tangent of the retainer ring and the peripheral wall, which are both connecting portions thereof, so that the retainer ring and the peripheral wall are movable relative to each other. It is supported. Therefore, the retainer ring can obtain the effect of the floating structure without interfering with the peripheral wall portion, and can absorb the axial inclination of each element and stably polish the wafer.
[0015]
The link means is rotatable in all directions around the pair portion when the portion paired with either the retainer ring or the peripheral wall portion forms a spherical pair. Therefore, the link means can absorb not only the vertical movement of the retainer ring but also the torsional motion, and the wafer polishing can be performed stably.
[0016]
In addition, the other pair of the link means has a sliding pair along the tangential direction in addition to the turning pair around the tangent, so that the vertical movement of the retainer ring is absorbed. The paired parts are slidable in the tangential direction, so that the clearance between the peripheral wall and the retainer ring is stably maintained, and the relative movement with high degree of freedom is realized by the sliding pair. The
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a wafer polishing head according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the wafer polishing head of the present invention, and FIG.
[0018]
The wafer polishing head 1 shown in FIG. 1 is provided in plural in the lower part of the carousel 30 which is a head driving mechanism in the overall wafer polishing apparatus shown in FIG. 7, and on the polishing pad 23 provided on the platen 24. It is designed to rotate around the planet.
[0019]
In FIG. 1, a wafer polishing head 1 is fixed to a head body 2 composed of a top plate portion 3 and a cylindrical peripheral wall portion 4, a diaphragm 5 stretched inside the head body 2, and a lower surface of the diaphragm 5. A disc-shaped carrier 6, an annular retainer ring 7 concentrically provided on the inner wall of the peripheral wall portion 4 and the outer peripheral surface of the carrier 6, and link means 8 for connecting the peripheral wall portion 4 and the retainer ring 7. It has.
[0020]
The head main body 2 is composed of a disk-shaped top plate portion 3 and a cylindrical peripheral wall portion 4 fixed below the outer periphery of the top plate portion 3, and the lower end portion of the head main body 2 is opened and becomes hollow. Yes. The top plate 3 is coaxially fixed to a shaft 9 connected to the carousel 30, and a flow path 15 communicating with the pressure adjustment mechanism 20 is formed in the shaft 9 in the vertical direction. Further, the lower end portion of the peripheral wall portion 4 is formed with a stepped portion 4a and an annular locking portion 10 projecting radially inward over the entire periphery, and further below the link means 8 is engaged. A link means first engaging portion 16 that is a portion to be formed is formed.
[0021]
A diaphragm 5 made of an elastic material such as fiber reinforced rubber is formed in a disk shape, and is fixed on a step portion 4 a formed on the inner wall of the peripheral wall portion 4 by a diaphragm fixing ring 11.
[0022]
A fluid chamber 14 is formed above the diaphragm 5 and communicated by a flow path 15 formed in the shaft 9. And the fluid inside the fluid chamber 14 is regulated by supplying fluid such as air from the pressure regulation mechanism 20 through the flow path 15 into the fluid chamber 14.
[0023]
The carrier 6 made of a highly rigid material such as ceramic is formed in a disk shape with a constant thickness, and is fixed by a carrier fixing ring 12 provided on the upper surface of the diaphragm 5.
[0024]
The retainer ring 7 is formed in an annular shape between the inner wall of the peripheral wall 4 and the outer peripheral surface of the carrier 6, and a slight gap is formed between the inner wall of the peripheral wall 4 and the outer peripheral surface of the carrier 6. It is vacant and arranged concentrically with the peripheral wall 4 and the carrier 6. The retainer ring 7 is fixed by a retainer ring fixing ring 13 provided on the upper surface of the diaphragm 5. The upper end surface and the lower end surface of the retainer ring 7 are formed to be horizontal and flat, and a link means second engagement portion 17 that is a portion to which the link means 8 is engaged is formed at a portion facing the peripheral wall portion 4. Has been.
[0025]
Link means 8 is provided between a first engagement portion 16 formed at the lower end of the peripheral wall portion 4 and a second engagement portion 17 formed on the retainer ring 7. In order to stably support the retainer ring 7, the link means 8 is provided at a plurality of positions at least at three or more around the retainer ring 7.
[0026]
As shown in FIGS. 2 and 3, the link means 8 is formed in a substantially triangular shape with a substantially constant thickness and is engaged with the first engagement portion 16 at the tip of the link means 8. The first end 8a, which is a part, is formed in a spherical shape. On the other hand, the 2nd end part 8b which makes the 2nd engaging part 17 and a pair is formed in the shape of a roller along the longitudinal direction.
[0027]
The first engaging portion 16 on the peripheral wall portion 4 side is hollow in a substantially triangular shape with the same thickness along the shape of the link means 8 from the right side of the peripheral wall portion 4 in FIGS. The link portion 8 is engaged with the support portion 16a with a slight gap. Further, the contact surface portion 16b of the support portion 16a, which is a portion with which the first end portion 8a is engaged, is formed so that the inner wall is spherical, and the spherical contact surface portion 16b and the first end of the link means 8 are formed. The portion 8a is in spherical contact with the portion 8a so as to form a turning pair. The link means 8 is supported so as to be rotatable in all directions around the first end portion 8a.
[0028]
The second engagement portion 17 is formed in a semi-cylindrical cross section so as to follow the roller shape of the second end portion 8b, and the second end portion 8b and the second engagement portion 17 are in line contact. It has become. Moreover, the part formed in the semi-cylindrical shape of the 2nd engaging part 17 is formed longer than the length of the longitudinal direction of the roller-shaped part of the 2nd edge part 8b. The retainer ring 7 is rotatable about the second engagement portion 17 and at the same time, the second end portion 8b is slidable in the longitudinal direction inside the second engagement portion 17, and the second end portion The part 8b and the second engaging part 17 form a turning pair, and at the same time, form a sliding pair along the longitudinal direction of the roller-shaped portion of the second end 8b.
[0029]
In the case of the present embodiment, the link means 8 is provided at six locations around the retainer ring 7 formed in an annular shape, as shown in FIG.
[0030]
When polishing a wafer using such a wafer polishing head, first, the wafer 22 is attached to a wafer attachment sheet 21 provided on the lower surface of the carrier 6. The wafer 22 is brought into contact with a polishing pad 23 provided on the upper surface of the platen 24 while being locked by the retainer ring 7. At this time, the lower end surface of the retainer ring 7 is also brought into contact with the polishing pad 23.
[0031]
Next, the pressure in the fluid chamber 14 is adjusted by allowing a fluid such as air to flow into the fluid chamber 14 from the flow path 15, and the pressure applied to the polishing pad 23 of the carrier 6 and the retainer ring 7 is adjusted. The carrier 6 and the retainer ring 7 have floating structures supported by the diaphragm 5 and can be independently displaced in the vertical direction, and the pressure applied to the polishing pad 23 can be adjusted by the pressure inside the fluid chamber 14. ing.
[0032]
The platen 24 is rotated while adjusting the pressing pressure of the carrier 6 and the retainer ring 7, and the wafer polishing head 1 is rotated planetarily.
[0033]
At this time, if the axial inclination of each element including the polishing pad 23 is too large, the movable range of the retainer ring 7 becomes small, that is, the clearance between the retainer ring 7 and the peripheral wall portion 4 becomes small. It may interfere with the peripheral wall 4. In this case, smooth displacement of the retainer ring 7 is hindered, and the effect of absorbing the axial inclination caused by the floating of the carrier 6 and the retainer ring 7 cannot be sufficiently obtained. As a result, the wafer is polished uniformly. I can't do that.
[0034]
However, when the retainer ring 7 and the peripheral wall portion 4 of the head body 2 are connected at a position separated by the link means 8, the movable range of the retainer ring 7 is reduced due to the axial inclination of each element. In addition, interference between the retainer ring 7 and the peripheral wall portion 4 can be prevented. Further, since the link means 8, the retainer ring 7 and the peripheral wall portion 4 form a link mechanism and are movable with respect to each other, the effect of the floating structure can be obtained and the axial inclination of each element can be absorbed. Wafer polishing can be performed stably.
[0035]
Since the first end portion 8a of the link means 8 is formed in a spherical shape and forms a spherical pair with the first engaging portion 16 of the peripheral wall portion 4, the link means 8 has all directions around the first end portion 8a. It becomes freely rotatable. Therefore, the link means 8 can absorb not only the vertical movement of the retainer ring 7 but also the torsional motion, and the wafer 22 can be stably polished.
[0036]
Further, the second end portion 8b of the link means 8 is formed in a roller shape, and the portion that makes a pair with the second engagement portion 17 of the retainer ring 7 is centered on the tangent of the roller-shaped portion of the second end portion 8b. By making a turning pair and making a sliding pair along the tangential direction, the movement of the retainer ring 7 in the vertical direction is absorbed, and the portions forming the pair are slidable in the tangential direction. The clearance between the peripheral wall portion 4 and the retainer ring 7 is stably maintained, and a relative motion with a high degree of freedom is realized by a sliding pair.
[0037]
As shown in FIG. 5, the link means has a first end portion 40 a that forms a pair with the peripheral wall portion 4 of the link means 40, and is a portion that forms a pair with the retainer ring 7. Even if the two end portions 40b are formed in a spherical shape, a desired effect can be obtained. Furthermore, as shown in FIG. 6, the first and second end portions 41a and 41b of the link means 41 can be formed in a spherical shape.
[0038]
【The invention's effect】
The wafer polishing head of the present invention has the following effects.
(1) The retainer ring and the peripheral wall portion of the head main body are connected at a position separated by the link means, so that the retainer ring can be moved even when the movable range of the retainer ring is reduced due to the axial inclination of each element. Interference between the ring and the peripheral wall can be prevented. At this time, since the smooth displacement of the retainer ring is not hindered, the wafer is stably locked.
(2) The link means forms a link mechanism having a rotating pair centered around at least a tangent line of the retainer ring and the peripheral wall portion which are both connecting portions thereof, so that the retainer ring and the peripheral wall portion are movable relative to each other. It is supported by. Therefore, the retainer ring can obtain the effect of the floating structure without interfering with the peripheral wall portion, and can absorb the axial inclination of each element and stably polish the wafer.
(3) The link means is rotatable in any direction around the pair portion because the portion that makes a pair with either the retainer ring or the peripheral wall portion is a spherical pair. Therefore, the link means can absorb not only the vertical movement of the retainer ring but also the torsional motion, and the wafer polishing can be performed stably.
(4) Of the linking means, the other pair of portions has a sliding pair along the tangential direction in addition to the rotating pair about the tangent, so that the vertical movement of the retainer ring is absorbed. At the same time, the parts that make up the kinematic pair are slidable in the tangential direction, so the clearance between the peripheral wall and the retainer ring is kept stable, and the relative movement with a high degree of freedom is realized by the sliding kinematic pair. Is done.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of an embodiment of a wafer polishing head of the present invention.
FIG. 2 is an enlarged cross-sectional view of the vicinity of the link means of FIG.
FIG. 3 is a plan view seen from above in FIG. 2;
FIG. 4 is a plan view seen from above showing an example of an embodiment of a wafer polishing head of the present invention.
FIG. 5 is a plan view seen from above in the vicinity of link means showing an example of an embodiment of a wafer polishing head of the present invention.
FIG. 6 is a plan view seen from above in the vicinity of link means showing an example of an embodiment of a wafer polishing head of the present invention.
FIG. 7 is an overall view of a wafer polishing apparatus using the wafer polishing head of the present invention.
FIG. 8 is a longitudinal sectional view showing a conventional wafer polishing head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Wafer grinding | polishing head 2 Head main body 3 Top plate part 4 Perimeter wall part 4a Perimeter wall part step part 5 Diaphragm 6 Carrier 7 Retainer ring 8 Link means 8a Link means 1st end part 8b Link means 2nd end part 9 Shaft 10 Locking part 11 Diaphragm fixing ring 12 Carrier fixing ring 13 Retainer ring fixing ring 14 Fluid chamber 15 Channel 16 Link means first engaging portion 17 Link means second engaging portion 20 Pressure adjusting mechanism 21 Wafer adhesion sheet 22 Wafer 23 Polishing pad 24 Platen 30 Carousel

Claims (2)

A head body composed of a top plate portion and a cylindrical peripheral wall portion provided below the outer periphery of the top plate portion;
A diaphragm stretched perpendicular to the head axis in the head body, and a pressure adjustment mechanism for adjusting a fluid pressure filled in a fluid chamber formed between the diaphragm and the head body;
A carrier that is fixed to the diaphragm and is displaceable in the head axis direction together with the diaphragm, and holds one surface of the wafer to be polished;
A retainer ring that is concentrically disposed between the inner wall of the peripheral wall portion and the outer periphery of the carrier, is fixed to the diaphragm and is displaceable in the head axis direction together with the diaphragm, and contacts the polishing pad during polishing. In a wafer polishing head equipped with
At a position where the retainer ring and the peripheral wall portion are separated from each other, there are provided at least three link means that are connected to the retainer ring and the peripheral wall portion and in which both the connecting portions turn into a pair, and the carrier, A wafer polishing head characterized by absorbing the axis inclination of the retainer ring, the vertical movement and torsional motion of the retainer ring, and preventing interference between the retainer ring and the peripheral wall portion . The link means is characterized in that a portion that is paired with either the retainer ring or the peripheral wall portion is a spherical pair, and the other is a slip pair along the tangential direction in addition to the turning pair. 2. The wafer polishing head according to 1.

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