JP2004090176A - Polishing apparatus and polishing method - Google Patents

Abstract

An object of the present invention is to provide a polishing apparatus and a polishing method capable of uniformizing a pressure distribution during polishing on a surface to be polished of a target to be polished and uniformly polishing the entire surface to be polished.
A holding head used in a polishing apparatus includes a container, a film that seals the container, adsorbs an object to be polished, and extends by dry air from a compressor, and a film inside the film. A pressing plate 110 arranged in the container, a position adjusting means 15 for expanding by the dry air from the compressor 80 and pressing the pressing plate 110, and an elastic film 12 provided on the pressing plate 110 on the side of the object to be polished. Having. On the surface of the pressing plate 110 on which the elastic film 12 is provided, there are provided annular pressing protrusions 111 and 112 for making the pressure distribution on the surface Sa of the object S to be polished uniform. In addition to applying a pressure corresponding to the positive pressure P2 to the object S to be polished, the position adjusting means 15 to which a positive pressure P1 higher than the positive pressure P2 is applied is applied via the annular pressing protrusion 111 to the object to be polished. S is pressed to control the pressure distribution on the polished surface Sa.
[Selection] Fig. 6

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a polishing apparatus for polishing an object to be polished, more specifically, a polishing apparatus capable of uniformly polishing a surface to be polished of the object to be polished, and a polishing apparatus for polishing the surface to be polished. The present invention relates to a polishing method capable of uniformly polishing.
[0002]
[Prior art]
2. Description of the Related Art A polishing apparatus is widely used, for example, for polishing an object to be polished, such as a semiconductor wafer, a glass plate for an LCD (Liquid Crystal Display), or a resin. A general polishing apparatus has a holding unit for holding an object to be polished, and a polishing unit for polishing the object to be polished, and a polished surface of the object to be polished is polished to a polishing surface of the polishing unit. It is brought into contact and polished by relative rotation in the plane direction.
[0003]
The holding means plays an important role in polishing the surface to be polished of the object to be polished with high quality.
Japanese Patent Application Laid-Open No. H11-138429 discloses that, in order to prevent the object to be held from shifting during polishing, the object to be polished is held by a suction force through a holding film having elasticity as a holding means. A polishing apparatus using a polishing head that holds by suction is disclosed.
[0004]
Japanese Patent Application Laid-Open Nos. 10-180627 and 2001-38604 each disclose a support head having a flexible film and a carrier head as means for holding an object to be polished.
These heads have a flexible film having elasticity, a support structure connected to the flexible film, or an edge load ring, and hold a semiconductor wafer to be polished on a substrate mounting surface of the flexible film. I do.
These heads can apply a predetermined pressure to a semiconductor wafer being polished by utilizing a flexible film and a support structure or an edge load ring.
[0005]
[Problems to be solved by the invention]
However, in a polishing head that holds an object to be polished via a holding film, since the holding film has elasticity, unevenness in the thickness of the object to be polished, dust on the holding surface that holds the object to be polished, and the like. Although it was possible to absorb irregularities and the like generated by the attachment, it was not possible to apply a desired pressure to the object to be polished.
[0006]
Until now, even in a head that can apply a predetermined pressure to a semiconductor wafer, only the outer peripheral portion of a circular wafer is mainly pressurized, and the pressure distribution near the center of the wafer is controlled. I couldn't.
So-called overpolishing (overpolishing) occurs in a portion of the wafer to be intensively pressed, in which the surface to be polished is polished more than the standard.
The non-uniform polishing such as overpolishing causes a decrease in the characteristics of the semiconductor wafer and a decrease in the yield.
[0007]
The present invention has been made in view of such a conventional technique and its problems, and an object of the present invention is to provide a polishing apparatus capable of uniformly polishing the surface to be polished of the object to be polished over the entire surface. To provide.
Another object of the present invention is to provide a polishing method capable of uniformly polishing the surface to be polished of the object to be polished over its entire surface.
[0008]
[Means for Solving the Problems]
A polishing apparatus according to the present invention for achieving the above object holds and presses an object to be polished placed on a polishing means disposed on a polishing platen and presses the object toward the polishing means. When,
By rotating the holding / pressing means, a rotating means for bringing the object to be polished into rotational contact with the polishing means,
Pressure medium supply means and
With
The holding and pressing means,
A container having an inner diameter larger than the object to be polished and having a first hole and a second hole through which a pressure medium is passed;
Sealing an open portion of the container where the object to be polished is located, capable of adsorbing the object to be polished, a stretchable film,
A plate-shaped pressing means disposed in the container inside the membrane in a loose fit state and having a third hole formed therein;
The pressure-medium supply means, which is located between the plate-shaped pressing means and a portion of the container facing the plate-shaped pressing means, and is supplied from a first hole formed in the container. Position adjusting means which is expanded by the pressure medium to position the plate-shaped pressing means in parallel with the object to be polished, and presses the plate-shaped pressing means,
Elastically pressing the object to be polished through the film, an elastic film provided on the object to be polished side of the plate-shaped pressing means,
Has,
A pressure medium supplied from the pressure medium supply means and supplied into the container from a second hole formed in the container extends the film through a third hole formed in the plate-shaped pressing means. Let
On the surface of the plate-shaped pressing means on which the elastic film is provided, there is provided an annular pressing protrusion for evenly pressing the object to be polished on the entire surface to be polished.
It is a polishing device.
[0009]
Further, in the polishing method of the present invention, a holding / pressing means in which a plate-like pressing means is disposed inside a stretchable film is prepared, and the object to be polished is held by the holding / pressing means. Placed on the substrate, the film is stretched by a first pressure, the object to be polished is brought into contact with the polishing means, and the object to be polished is partially pressed by the plate-shaped pressing means, The second pressure further presses an annular pressing projection provided on the object to be polished of the plate-like pressing means so that the pressing of the object to be polished to the entire surface to be polished becomes uniform. The holding and pressing means and the polishing means are relatively rotated to polish the surface to be polished of the object to be polished.
[0010]
In the present invention, an open portion of the container of the holding / pressing means where the object to be polished is located is sealed with a stretchable film. This film is extended by the pressure medium supplied from the pressure medium supply means through the second hole formed in the container, and presses the adhering surface of the object to be polished to the polishing means.
In the container inside the membrane, a plate-shaped pressing means is arranged in a loosely fitted state. The plate-shaped pressing means is pressed by the position adjusting means being expanded by the pressure medium supplied from the pressure medium supplying means through the first hole formed in the container.
When the plate-shaped pressing means is pressed by the position adjusting means, the object to be polished is pressed via the elastic film provided on the surface of the plate-shaped pressing means on the object-to-be-polished, and the stretchable film. You.
In the present invention, the force by the position adjusting means is transmitted to the object to be polished through the annular projection provided on the surface of the plate-shaped pressing means on the object to be polished, thereby forming a film on the surface to be polished. In addition to the pressure for extending the pressure, a pressing force by the position adjusting means can be appropriately applied.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First embodiment
First, a general schematic configuration of a polishing apparatus will be described with reference to FIG.
A polishing apparatus 1 shown in FIG. 1 has a holding head 5 as a holding / pressing means for holding and pressing an object to be polished, a polishing platen 2, and a polishing cloth 3 provided on the surface thereof. The polishing platen 2 and the polishing cloth 3 constitute one embodiment of the polishing means of the present invention.
In the following, a semiconductor wafer will be described as an example of the object to be polished.
[0012]
As an example of the holding head 5, a holding head 500 shown in FIG. 2 will be described.
The holding head 500 has a base 17, a backing material 8, a retainer ring 9, a pressing plate 11, and a ring-shaped tube 15.
[0013]
The backing material 8 is a stretchable soft thin film formed of, for example, polyurethane, polyester, or synthetic rubber having a thickness of about 1 mm, and adsorbs and holds a semiconductor wafer (hereinafter, wafer) S by water adsorption or the like. can do.
[0014]
The retainer ring 9 is an annular member whose inner diameter is slightly larger than the outer diameter of the wafer S, and is formed of a resin such as an epoxy resin or a polyacetal resin.
[0015]
The base 17 has, for example, a disk shape with a predetermined thickness, holds the backing material 8, and forms a closed space CS with the backing material 8.
When fixing the backing material 8 with the base 17, the backing material 8 is sandwiched between the base 17 and the retainer ring 9, and the outer periphery of the base 17 and the inner periphery of the retainer ring 9 are fitted to each other. 9 is fixed.
The base 17 and the retainer ring 9 constitute one embodiment of the container of the present invention.
[0016]
As described above, since the inner diameter of the retainer ring 9 is larger than the outer diameter of the wafer S, when the retainer ring 9 is mounted on the base 17, the wafer S adsorbed on the mounting surface of the backing material 8 is almost covered. By defining the length of the retainer ring 9 in the longitudinal direction, it is possible to prevent the wafer S from jumping out during polishing.
[0017]
The rotating shaft 6 is connected to the base 17 on the side opposite to the side forming the closed space CS with the backing material 8.
A pressure medium such as dry air pressurized to a positive pressure P2 is supplied to the closed space CS by a second hole 81 provided in the rotary shaft 6 and penetrating through the base 17 and communicating with the closed space CS. It is possible to do.
The dry air is sent, for example, by the compressor 80 shown in FIG. 1, and the positive pressure P2 is 9800 to 49000 ° Pa as an example.
The compressor 80 corresponds to one embodiment of a pressure medium supply unit in the present invention.
[0018]
Due to the pressure of the dry air of the positive pressure P2, the backing material 8 tends to expand to the outside of the retainer ring 9, and the expansion force causes the polishing target surface Sa of the wafer S adsorbed by the backing material 8 to be removed from the polishing cloth 3. The polishing surface Sb is pressed and brought into contact.
Even if the backing material 8 is soft and uneven in the thickness of the wafer S, or dust or the like adheres to the holding surface of the wafer S, the backing material 8 absorbs the unevenness caused by the unevenness and changes the polished surface Sa of the wafer S. It is possible to polish as uniformly as possible.
[0019]
The pressing plate 11 is an embodiment of the plate-shaped pressing means in the present invention.
The pressing plate 11 is arranged to face the wafer S via the backing material 8 in the closed space CS. An elastic film 12 is provided on a pressing surface of the pressing plate 11 that presses the holding surface of the wafer S.
The elastic film 12 is for preventing the pressing plate 11 from directly contacting the backing material 8 and for uniformly pressing the surface to be polished Sa without being affected by uneven thickness of the backing material 8 or distortion of the pressing plate 11. It is.
[0020]
3A and 3B are diagrams for illustrating the shape of the pressing plate 11 in the holding head 500. FIG. 3A is a plan view as viewed from the pressing surface side, and FIG. 3B is a cross section as viewed from the cross section III-III. FIG.
As can be seen from the illustration in FIG. 3, the pressing plate 11 is disk-shaped, and has a ring-shaped convex portion having a width W on the outer peripheral portion of the pressing surface.
The ring-shaped projection is one embodiment of the annular pressing projection of the present invention.
[0021]
The pressing plate 11 and the elastic film 12 are provided with a third hole 14 so that the backing material 8 can be pressurized by dry air.
In FIG. 3A, as an example, a third hole 14 is provided in a cross shape from the center of the pressing plate 11, but the shape, the number, the arrangement position, and the like of the third hole 14 are different from those of the backing material 8. What is necessary is just to determine suitably so that the desired pressure to pressurize may be obtained.
[0022]
The pressing plate 11 is pressed by the ring-shaped tube 15 from a surface opposite to the pressing surface, as illustrated in FIG.
The ring-shaped tube 15 is obtained by forming a tube having a circular cross section into a ring shape, and is arranged between the pressing plate 11 and the base 17 in the closed space CS as illustrated in FIG.
The ring-shaped tube 15 expands when dry air having a positive pressure P1 higher than the positive pressure P2 is sent in, and can press the pressing plate 11.
The ring-shaped tube 15 corresponds to one embodiment of the position adjusting means in the present invention.
[0023]
The dry air of the positive pressure P1 is provided, for example, on the rotating shaft 6 and is sent by the compressor 80 through the first hole 82 penetrating through the base 17 and communicating with the ring-shaped tube 15.
The value of the positive pressure P1 is, for example, 9800 to 98000 ° Pa.
[0024]
The above-described holding head 500 has a structure in which the backing material 8 is held using the base 17 and the retainer ring 9. However, the shape and holding method of the backing material are not limited to those described above, and any shape may be used as long as a closed space is formed by the backing material and a desired pressure can be applied to the backing material.
For example, a member having elasticity may be attached to the retainer ring 9 and this member may be connected to the pressing plate 11 so that the backing material and the pressing plate 11 are simultaneously held.
[0025]
The holding head 500 is rotatable about the rotation shaft 6 via the rotation shaft 6 by the motor 60 serving as the rotation means of the present invention.
The rotating shaft 6 is held by a support arm 7, as illustrated in FIG. The center of rotation of the rotating shaft 6 coincides with the centers of the pressing plate 11 and the ring-shaped tube 15 of the holding head 5,500.
[0026]
The polishing platen 2 is provided with a circular polishing cloth holding surface having a diameter, for example, twice or more the diameter of the wafer S, for holding the polishing cloth 3, and is provided on a surface opposite to the polishing cloth holding surface. The motor 45 can rotate around the rotating shaft 4 via the connected rotating shaft 4.
[0027]
The polishing cloth 3 for polishing the wafer S is formed of, for example, a nonwoven fabric made of an elastic polyester resin, and as shown in FIG. , And are adhered and fixed by an adhesive means such as a double-sided adhesive tape.
[0028]
Next, an operation in the case where the wafer S is subjected to chemical mechanical polishing (CMP) using the polishing apparatus 1 having the above configuration will be described.
CMP is a polishing technique that uses a chemically active abrasive and combines the chemical action between the abrasive and the object to be polished and the mechanical grinding action of the abrasive particles in the abrasive. CMP is characterized in that the deteriorated layer formed on the surface to be polished is small, the polishing rate is high, and the surface of the semiconductor wafer can be flattened globally. CMP is an important technology in a semiconductor manufacturing process, for example, in a process of flattening an interlayer insulating film, forming a metal plug, and forming a buried metal wiring in a multilayer wiring forming process.
[0029]
For example, in the step of using CMP in a dual damascene method of forming a metal wiring by forming a metal wiring by simultaneously burying the wiring groove and the contact hole with a metal in the interlayer insulating film in addition to forming a wiring groove in addition to a wiring groove. The wafer S is configured as shown in the sectional view of FIG.
In FIG. 4A, for example, an interlayer insulating film 20 made of, for example, silicon oxide is formed on a semiconductor substrate 10 made of silicon or the like in which an impurity diffusion region (not shown) is appropriately formed.
In the interlayer insulating film 20, a predetermined pattern of the barrier film 25, which will be a contact and a metal wiring in the future, is formed in a groove shape.
For example, when the material forming the wiring is copper and the interlayer insulating film is formed of silicon oxide, the barrier film 25 has a large diffusion coefficient into silicon oxide and is easily oxidized. It is provided for.
[0030]
On the barrier film 25, for example, a copper film 30 formed by a method such as a plating method, a CVD (Chemical Vapor Deposition) method, or a sputtering method is formed so as to fill the groove.
[0031]
The wafer S having the above configuration is held by a holding head 5 having a configuration like the holding head 500, for example. The holding head 5 holding the wafer S moves to a position facing the polishing platen 2 so that the surface to be polished Sa of the wafer S can come into contact with the polishing surface Sb of the polishing pad 3.
The holding head 5 is moved in the direction of arrow Z in FIG. 1 via the rotating shaft 6 and the support arm 7 to bring the polished surface Sa into contact with the polished surface Sb with a predetermined pressure.
In FIG. 1, the wafer Z is held with the surface to be polished Sa facing downward in the figure, and therefore, in FIG. 4, the arrow Z points upward in the figure.
[0032]
In the above contact state, the polishing platen 2 and the holding head 5 are respectively moved while the polishing agent (slurry) L is supplied from the polishing agent supply pipe 13 to the interface between the polishing surface Sb and the surface to be polished Sa of the polishing pad 3. For example, the same rotation speed 90 min in the directions of arrows Ra and Rb in FIG.^-1Rotate with.
[0033]
As described above, as shown in FIG. 4B, the excess copper film 30 and the barrier film 25 on the interlayer insulating film 20 are chemically and mechanically polished, and the copper wiring 35 and the contact 40 are formed.
[0034]
When performing CMP of the wafer S using the holding head 500 having a structure as shown in FIG. 2 as the holding head 5, the wafer S is closed by forming the backing material 8 using the base 17 and the retainer ring 9. Due to the pressure of the dry air of the positive pressure P2 sent into the space CS, it is pressed against the polishing surface Sb in the direction of arrow Z.
[0035]
Since the backing material 8 is a soft thin film, even if the thickness of the wafer S is uneven or dust or the like adheres to the holding surface opposite to the surface to be polished Sa, the unevenness caused by the unevenness occurs. It can be absorbed.
With this structure, the pressure distribution on the surface to be polished Sa is made uniform.
[0036]
However, simply holding the backing material 8 and pressurizing it with dry air from the back surface makes it difficult to uniformly hold and press the wafer S because the backing material 8 is a soft thin film. It is difficult to make the pressure distribution over the entire surface Sa uniform.
[0037]
Therefore, in the holding head 500, the pressing plate 11 is arranged so as to face the wafer S via the backing material 8.
During polishing, the pressing plate 11 is pressed by the ring-shaped tube 15 from the pressed surface opposite to the pressing surface that presses the wafer S.
The ring-shaped tube 15 is expanded by being pressurized by the dry air of the positive pressure P <b> 1 sent through the first hole 82, and presses the pressing plate 11.
Therefore, the wafer S is subjected to pressure control of the surface to be polished Sa by the pressure of the dry air of the positive pressure P2 and the pressing force of the pressing plate 11 pressed with the dry air of the positive pressure P1.
[0038]
However, as shown in FIGS. 2 and 3, the pressing plate 11 has the ring-shaped convex portion 112 formed only on the outer peripheral portion of the circular pressing surface. Therefore, the force tends to concentrate on the outer periphery of the circular wafer S, and it is difficult to control the pressure distribution near the center of the wafer S.
[0039]
As an example, FIG. 5 is a graph showing the distribution of the film thickness (remaining film) F at the end of polishing when the wafer S having the structure shown in FIG. 4 is subjected to CMP using the holding head 500.
The vertical axis of the graph of FIG. 5 indicates the residual film (Å = 0.1 × 10^-3μm), and the horizontal axis is the distance (mm) from the center of the wafer S.
The outer diameter of the wafer S and the pressing plate 11 was 200 mm, and the dimension C, which is the inner diameter of the ring-shaped protrusion 112 of the pressing plate 11, was 190 mm, that is, the width W of the ring-shaped protrusion 112 was 5 mm. The height E of the ring-shaped convex portion 112 is not so high as it does not affect the width W, and the elastic film 12 in the concave portion formed by the ring-shaped convex portion 112 has a backing during polishing. What is necessary is just to determine suitably so that it does not contact the material 8. Here, it was set to 0.1 mm as an example.
From FIG. 5, it can be seen that a portion of 10 to 20 mm from the outer periphery of the wafer S is easily polished, and overpolishing has occurred.
[0040]
Semiconductor wafers tend to be larger in recent years. When the wafer diameter was small, the polished surface of the wafer could be uniformly polished even by using the holding head 500 having the pressing plate 11 shown in FIG. However, as described above, when the wafer diameter increases to about 200 mm, the pressure plate 11 has a structure having the ring-shaped convex portion 112 only on the outer peripheral portion, and therefore, the pressure distribution on the surface to be polished can be made uniform. It becomes difficult.
[0041]
Second embodiment
A second embodiment of the present invention capable of equalizing the pressure distribution on the polished surface Sa even when the diameter of the wafer S is increased will be described below.
FIG. 6 is a sectional view of a holding head 50 which is a second embodiment of the holding head according to the present invention.
The holding head 50 has a pressing plate 110 shown in FIG. 7 instead of the pressing plate 11 of the holding head 500 illustrated in FIG.
FIG. 7A is a plan view of the pressing plate 110 viewed from the pressing surface side, and FIG. 7B is a cross-sectional view of the pressing plate 110 taken along a cross section II.
[0042]
The pressing plate 110 has a ring-shaped convex portion 111 as a pressing projection inside the ring-shaped convex portion 112 in addition to the ring-shaped convex portion 112 on the outer peripheral portion.
The pressing protrusions for making the pressure distribution on the polished surface Sa of the wafer S uniform are ring-shaped as shown in FIG. 7 because the pressure distribution on the polished surface Sa is concentric about the rotation axis. It is preferable that it is a convex part.
Since the configuration and function of the holding head and the polishing apparatus other than the pressing plate 110 are the same as those of the holding head 500, detailed description will be omitted.
[0043]
The first ring-shaped protrusion 111 and the second ring-shaped protrusion 112 of the pressing plate 110 may be formed by cutting, or the ring-shaped protrusion may be welded, bonded, and screwed to a flat disk. It may be fixed by connecting means such as fastening. Here, in consideration of manufacturing convenience and the like, it is assumed to be formed by cutting.
The space between the ring-shaped convex portions 111 and 112 and the flat disk may be configured as a tapered surface or a curved surface. In addition, it is preferable that the corners of the convex portions be curved or chamfered from the viewpoint of protection of the wafer S and the like.
[0044]
Example
An example in which CMP is actually performed on the wafer S using the polishing apparatus according to the present invention using the pressing plate 110 shown in FIG. 7 will be described.
The outer diameter of the circular wafer S and the pressing plate 110 is 200 mm, and in the pressing plate 110, the dimension A, which is the outer diameter of the first ring-shaped protrusion, is 85% of the outer diameter of the wafer S and the pressing plate 110. The dimension B, which is 170 mm, which is the inner diameter of the first ring-shaped projection, is 85%, which is 50% of the dimension A.
Regarding the second ring-shaped convex portion 112, the dimension C was 190 mm, which is 95% of the outer diameter of the wafer S, and the dimension E was 0.1 mm, as in the case of the experiment shown in FIG. The dimension D, which is the difference between the heights of the first and second ring-shaped protrusions 111 and 112, is 0.05 mm from the height of the first ring-shaped protrusion 111.
[0045]
In such a case, the portion having a radius of 85 to 95 mm of the wafer S is not directly polished by the pressing plate 110, so that it is difficult to be polished.
Conversely, at a portion outside the radius of 95 mm and a portion with a radius of 42.5 to 85 mm, the holding surface of the wafer S is directly pressed, so that it is easily polished.
Thereby, the pressure distribution on the surface to be polished Sa can be controlled.
However, the polishing of the wafer S does not necessarily proceed only in the portion pressed by the ring-shaped convex portion of the pressing plate 110, and the polishing of the non-pressed portion does not necessarily proceed. Changes the polishing rate.
[0046]
FIG. 8 shows a graph of the polishing result.
The vertical axis of the graph of FIG. 8 indicates the residual film (Å = 0.1 × 10^-3μm), and the horizontal axis is the distance (mm) from the center of the wafer S.
Comparing with the result shown in FIG. 5 when the first ring-shaped convex portion 111 does not exist, it can be seen that the polishing rate near the center of the wafer S is controlled. In particular, it can be seen that the polishing rate is reduced in a portion from the outer peripheral portion of the wafer S to the inside of 20 mm, and that the polishing over the entire surface S to be polished of the wafer S is made uniform.
[0047]
Regarding the shapes of the first and second ring-shaped convex portions 111 and 112, if the widths of the respective rings are too narrow, stress concentration tends to occur, which is not preferable in making the pressure distribution of the polished surface Sa uniform.
Conversely, if the widths are too large, the area for transmitting the force to the wafer S becomes too large, and it becomes difficult to control the pressure distribution on the polished surface Sa.
In view of the above reasons and the results of the above embodiment, the shapes of the first and second ring-shaped convex portions 111 and 112 are defined as follows.
[0048]
The dimension A of the first ring-shaped projection 111 is set to 60 to 85% of the diameter of the circular wafer S so that the pressure distribution on the surface to be polished Sa can be controlled. Preferably, it is set to 70 to 80% so that the area for transmitting the force to the surface to be polished Sa does not become too large. More preferably, it is set to 72.5% to 77.5% at which good results are obtained experimentally.
For the dimension B, the first ring-shaped convex portion 111 is formed by taking a value up to 95% of the dimension A. Preferably, it is set to 50 to 90% so that the area for transmitting the force to the surface to be polished Sa does not become too large. More preferably, it is 75-85% so that stress concentration on the surface to be polished Sa does not occur.
[0049]
The shape of the second ring-shaped convex portion 112 is such that the dimension C is smaller than the outer diameter of the circular wafer S and is 95% or more so that the polishing amount at the outer peripheral portion of the wafer S is ensured. And Preferably, the diameter is less than the outer diameter of the wafer S and 97.5% or more so that the pressure distribution in the outer peripheral portion of the wafer S can be easily controlled. More preferably, it is smaller than the outer diameter and 98.5 or more so that the outer peripheral portion of the wafer S is not excessively polished.
[0050]
The dimension D, which is the difference between the heights of the first ring-shaped projection 111 and the second ring-shaped projection 112, is not far from the size of the dimension E, which is the height of the second ring-shaped projection 112. To within ± 0.2 mm. Preferably, it is within ± 0.1 mm for easy control of the pressure distribution on the surface to be polished of the wafer S. More preferably, the distance is within ± 0.05 mm so that the pressing force by the first and second ring-shaped convex portions 111 and 112 is transmitted uniformly.
[0051]
Regarding the size of the dimension E, which is the height of the second ring-shaped convex portion 112, the influence of physical characteristics such as thickness and hardness of the elastic film adhered to the convex portion and various conditions such as temperature. receive. Generally, as described above, the elastic film 12 is in contact with the backing material 8 at the second ring-shaped protrusion 112 and the first ring-shaped protrusion 111, and the first and second ring-shaped protrusions 111 are formed. , 112 so as not to contact the backing material 8 during polishing. However, it is not always good that they are not in contact with each other, and the optimum condition changes according to the pressure distribution of the surface to be polished Sa, which depends on various parameters such as the composition of the slurry used for polishing and the operating condition of the polishing apparatus. Therefore, although the dimension E is not particularly defined here, a value of about 0.1 mm is used as an example.
[0052]
According to the polishing apparatus using such a holding head 50, the vicinity of the central portion of the wafer S is appropriately adjusted independently of the pressure applied to the wafer S via the backing material 8 by the dry air of the positive pressure P2. Force can be applied.
Therefore, the pressure distribution near the center of the wafer S can be controlled, and the pressure distribution on the polished surface Sa can be made uniform.
[0053]
Third embodiment
The second ring-shaped convex portion 112 is not always necessary depending on polishing conditions. The second ring-shaped convex portion 112 is required when it is desired to secure the polishing amount in the outer peripheral portion of the wafer S, particularly, in a portion from the outer periphery to the vicinity of 5 mm inside.
Since the polishing quality in the above-mentioned region affects the yield of the wafer, it is desired that the polishing amount in this portion be matched with the polishing amount in the central portion of the wafer as much as possible to make the remaining film amount uniform. Further, when an unnecessary film remains on the outer peripheral portion, the film may be peeled off and become a foreign substance, and may remain on the wafer to deteriorate the yield.
Such a situation changes depending on the composition of the slurry and the wafer, the operating condition of the polishing apparatus, and the like, for example, even if a wafer having the same diameter is polished, an unnecessary film remains or does not remain on the outer peripheral portion. .
Therefore, the second ring-shaped convex portion 112 is necessary in a situation where an unnecessary residual film is present on the outer peripheral portion when the polishing is actually performed, but in other cases, the pressing plate without the ring-shaped convex portion 112 is required. May be used.
[0054]
FIG. 9 shows a pressing plate 120 used in the third embodiment of the present invention, which does not have the second ring-shaped protrusion 112 and has only the first ring-shaped protrusion 111.
FIG. 9A is a plan view of the pressing plate 120 as viewed from the pressing surface side, and FIG. 9B is a cross-sectional view of the pressing plate 120 taken along a section II-II.
The dimensions A and B and the height of the first ring-shaped protrusion 111 are defined according to the case of the pressing plate 110.
[0055]
In the present invention, even when the diameter of the wafer S is further increased, another ring-shaped protrusion is provided between the first ring-shaped protrusion 111 and the second ring-shaped protrusion 112. It is possible to provide a part.
Thereby, even when the diameter of the wafer S is increased, the pressure distribution over the entire surface to be polished Sa can be made uniform.
[0056]
Note that the present invention is not limited to the above embodiment.
For example, the position adjusting means is a ring-shaped tube 15 which expands with dry air in the above embodiment, but a mechanical actuator which operates using pressure can be used.
Also, the dimensions of the pressing plate may be appropriately defined according to the dimensions of the wafer to be polished.
Further, the present invention is applicable to various polishing processes such as polishing of a glass plate or a resin as well as removal of plating as well as a semiconductor wafer.
[0057]
【The invention's effect】
As described above, according to the present invention, during polishing, the pressure distribution on the surface to be polished of the object to be polished can be made uniform. Therefore, it is possible to provide a polishing apparatus capable of uniformly polishing the surface to be polished on the entire surface.
Further, according to the present invention, it is possible to provide a polishing method capable of uniformly polishing the surface to be polished of the object to be polished over the entire surface.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a polishing apparatus according to the present invention.
FIG. 2 is a sectional view showing a holding head of the polishing apparatus shown in FIG. 1 according to the first embodiment;
3 (a) is a front view showing one embodiment of a pressing plate of the holding head shown in FIG. 2 from a pressing surface thereof, and FIG. 3 (b) is a diagram showing a state in FIG. 3 (a). It is sectional drawing seen from section III-III.
FIG. 4 is a cross-sectional view for explaining an example of CMP of a semiconductor wafer. FIG. 4 (a) shows a state before CMP, and FIG. 4 (b) shows a state after CMP. .
FIG. 5 is a graph showing a distribution of a residual film of the semiconductor wafer when the semiconductor wafer is flattened and polished using the pressing plate of FIG. 3;
FIG. 6 is a sectional view showing a holding head of the polishing apparatus shown in FIG. 1 according to a second embodiment.
7A is a front view showing one embodiment of a pressing plate of the holding head shown in FIG. 6 from the pressing surface, and FIG. 7B is a front view of FIG. 7A. It is sectional drawing seen from section II.
8 is a graph showing a distribution of a residual film of the semiconductor wafer when the semiconductor wafer is flattened and polished using the pressing plate of FIG. 7;
9A is a front view showing a pressing plate used in the polishing apparatus shown in FIG. 1 according to a third embodiment of the present invention, viewed from the pressing surface; FIG. 9B is a front view of FIG. FIG. 2A is a cross-sectional view as viewed from a cross section II-II.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 2 ... Polishing table, 3 ... Polishing cloth, 4, 6 ... Rotating shaft, 5, 50, 500 ... Holding head, 7 ... Support arm, 8 ... Backing material, 9 ... Retainer ring, 10 ... Semiconductor Substrate, 11, 110, 120: Press plate, 12: Elastic film, 13: Abrasive supply tube, 14, 81, 82: Hole, 15: Ring-shaped tube, 17: Base, 20: Interlayer insulating film, 25: Barrier Film, 30: Copper film, 35: Copper wiring, 40: Contact, 45, 60: Motor, 80: Compressor, 111: First ring-shaped protrusion, 112: Second ring-shaped protrusion, S: Semiconductor wafer , Sa: polished surface, Sb: polished surface, L: abrasive (slurry), CS: closed space

Claims (7)

Holding and pressing means for holding an object to be polished placed on the polishing means arranged on the polishing platen, and pressing against the polishing means side,
By rotating the holding / pressing means, a rotating means for bringing the object to be polished into rotational contact with the polishing means,
Pressure medium supply means,
The holding and pressing means,
A container having an inner diameter larger than the object to be polished and having a first hole and a second hole through which a pressure medium is passed;
Sealing an open portion of the container where the object to be polished is located, capable of adsorbing the object to be polished, a stretchable film,
A plate-shaped pressing means disposed in the container inside the membrane in a loose fit state and having a third hole formed therein;
The pressure-medium supply means, which is located between the plate-shaped pressing means and a portion of the container facing the plate-shaped pressing means, and is supplied from a first hole formed in the container. Position adjusting means which is expanded by the pressure medium to position the plate-shaped pressing means in parallel with the object to be polished, and presses the plate-shaped pressing means,
Elastically pressing the object to be polished through the film, an elastic film provided on the object to be polished side of the plate-shaped pressing means,
Has,
A pressure medium supplied from the pressure medium supply means and supplied into the container from a second hole formed in the container extends the film through a third hole formed in the plate-shaped pressing means. Let
A polishing apparatus, comprising: an annular pressing protrusion for uniformizing pressing of the object to be polished over the entire surface to be polished on a surface of the plate-shaped pressing means on which the elastic film is provided. An outer diameter of the first annular pressing projection is 72.5% to 77.5% of an outer diameter of the disk-shaped object to be polished; The polishing apparatus according to claim 1, wherein the inner diameter of the first annular pressing projection is 75 to 85% of the outer diameter of the first annular pressing projection. A second annular pressing protrusion is further provided on an outer peripheral portion of the plate-like pressing means, and an inner diameter of the second annular pressing protrusion is 98.5% of an outer diameter of the disk-shaped object to be polished. The polishing apparatus according to claim 2, which is at least less than 100%. 4. The polishing apparatus according to claim 3, wherein heights of the first annular pressing protrusion and the second annular pressing protrusion are different. 5. The polishing apparatus according to claim 4, further comprising at least one third annular pressing projection between the first and second annular pressing projections. The polishing apparatus according to claim 1, wherein the position adjusting unit is an elastic annular tube concentric with the center of rotation of the rotating unit, the holding / pressing unit, and the plate-shaped pressing unit. Preparing holding and pressing means in which a plate-shaped pressing means is arranged inside a stretchable film,
The object to be polished is held by the holding / pressing means and placed on the polishing means,
Extending the film by the first pressure to bring the object to be polished into contact with the polishing means, partially pressing the object to be polished by the plate-shaped pressing means,
The second pressure further presses the annular pressing protrusion provided on the object to be polished of the plate-like pressing means so that the pressure of the object to be polished to the entire surface to be polished is uniform,
A polishing method for polishing the surface to be polished of the object to be polished by relatively rotating the holding / pressing means and the polishing means.

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