WO2003078103A1

WO2003078103A1 - Polishing equipment, and method of manufacturing semiconductor device using the equipment

Info

Publication number: WO2003078103A1
Application number: PCT/JP2003/003150
Authority: WO
Inventors: Susumu Hoshino
Original assignee: Nikon Corporation
Priority date: 2002-03-20
Filing date: 2003-03-17
Publication date: 2003-09-25
Also published as: JP2003266300A; KR20040091761A; AU2003213394A1; TW200400099A

Abstract

Polishing equipment, comprising a polishing head (30) having an opened hollow mixing tank (32) on the opposite side of the side thereof where a polishing pad (36) is installed, a slurry feed mechanism (50) for feeding slurry into the mixing tank (32), an additive liquid feed mechanism (60) for feeding additive liquid used by adding to the slurry into the mixing tank (32), and a mixed liquid feed tube (34) extending from the mixing tank (32) into the polishing head (30) and opened to near the rotating center of the polishing pad (36), wherein the slurry fed by the slurry feed mechanism (50) and the additive liquid fed by the additive liquid feed mechanism (60) are fed from the mixed liquid feed tube (34) to the outside of the polishing pad (36) in the mixed state in the mixing tank (32).

Description

m Itoda β polishing apparatus and method for manufacturing semiconductor device using this polishing apparatus

The present invention relates to a polishing apparatus for flattening an object to be polished such as a silicon wafer, and more particularly, to a polishing apparatus for performing chemical mechanical polishing while supplying a slurry to a surface to be polished of the object to be polished. The present invention also relates to a method for manufacturing a semiconductor device using the polishing apparatus for polishing a surface of a semiconductor wafer. Background art

In recent years, with the miniaturization and complexity of IC structures, the number of layers of multilayer wiring formed on semiconductor substrates has tended to increase, and planarization of the substrate surface after forming each thin film has become more important. . The accuracy of the surface flattening performed after the formation of each thin film is poor, and if unevenness is obtained, the surface step becomes large, and there is a possibility that insulation failure between wirings or short-circuit may occur. Further, in the lithographic process, if the surface of the semiconductor substrate has many irregularities, defocus may occur, and a fine pattern may not be formed.

Conventionally, a chemical mechanical polishing (CΜ) method has been known as a technique for precisely planarizing the surface of a semiconductor substrate, and an apparatus called a CMP apparatus is used as an apparatus for performing this method. C In general, this CMP apparatus performs polishing by contacting a polishing pad attached to a polishing head while supplying a polishing liquid (called slurry) containing silica particles to a surface to be polished of a semiconductor substrate. It has a configuration.

FIG. 3 schematically shows an example of such a conventional CMP apparatus. here The CMP apparatus shown in FIG. 1 has a surface plate 92 for holding a semiconductor substrate 91 to be polished substantially horizontally, and a polishing device provided above the surface plate 92 and having a polishing pad 95 adhered to a lower surface thereof. It has a head 93. When polishing the semiconductor substrate 91, the surface plate 92 holding the semiconductor substrate 91 is rotated about a vertical axis, and the polishing head 93 is rotated about the vertical axis to polish the polishing pad 95. From above the substrate 91. Here, the diameter of the polishing pad 95 is smaller than the diameter of the semiconductor substrate 91, and the polishing head 93 reciprocates in a direction (horizontal direction) parallel to the contact surface of the semiconductor substrate 91 (horizontal direction). (Swinging) The surface of the substrate 91 is evenly polished by moving. During this polishing, the slurry in the slurry tank 96 is sucked up by the pump 97 and polished from the slurry supply pipe 98 through the slurry supply pipe 94 provided inside the polishing head 93. It is supplied outside the pad 95, that is, on the surface to be polished of the semiconductor substrate 91.

Further, in such polishing of the semiconductor substrate 91, a necessary additive liquid (chemical solution) depending on the purpose may be added to the slurry. This additive is known to promote the flattening of the substrate surface, and is supplied onto the surface to be polished of the semiconductor substrate 91 in a state of being mixed with the slurry. When the additive liquid is mixed with the slurry, a mixed liquid in which the slurry and the additive liquid are mixed is prepared in advance in the slurry tank 96, and the mixed liquid is added to the semiconductor substrate 9 in the same manner as when only the slurry is supplied. Supply on the surface to be polished.

By the way, when the additive liquid is mixed with the slurry as described above, it is known that if the additive liquid is mixed with the slurry in advance, the effect of the additive liquid is not sufficiently exhibited. For this reason, it is preferable that the slurry and the additive liquid are mixed immediately before being supplied onto the surface to be polished of the object to be polished. However, when the above-mentioned conventional polishing apparatus is used, there is no other way than to mix the slurry and the additive liquid in advance, and thus the effect of the additive liquid may not be sufficiently obtained. Disclosure of the invention

The present invention has been made in view of such a problem, and the slurry and the additive liquid can be mixed immediately before being supplied onto the surface to be polished of the object to be polished, and the effect of the additive liquid is sufficiently exhibited. It is an object of the present invention to provide a polishing apparatus capable of improving the polishing accuracy of a substrate.

Another object of the present invention is to provide a method for manufacturing a semiconductor device using the polishing apparatus for polishing a surface of a semiconductor wafer.

A polishing apparatus according to the present invention comprises: a platen for holding a workpiece; and a polishing head having a polishing pad attached to a surface of the workpiece held on the surface opposite to the surface to be polished. A polishing apparatus for polishing a surface to be polished by bringing a polishing pad into contact with the surface to be polished; a slurry supply mechanism for supplying slurry to the polishing head; An additive liquid supply mechanism for supplying the additive liquid to the polishing head; and a slurry provided inside the polishing head and mixing the slurry supplied from the slurry supply mechanism with the additive liquid supplied from the additive liquid supply mechanism. And a mixed liquid supply unit for supplying the mixture to the outside of the polishing pad from an opening located near the center of rotation of the polishing pad.

In the polishing apparatus according to the present invention, the stirring member fixed to one of the polishing head and the polishing head holder that rotatably holds the polishing head is located in the mixed liquid supply section. Is preferred. In this case, it is preferable that the stirring member has a projection shape or a spiral groove shape. Further, it is preferable that at least a part of the inner wall of the mixed liquid supply section is provided with a protruding or spiral groove shaped stirring member. Further, it is preferable that the surface plate holds the object to be polished so that the surface to be polished faces upward, and the polishing pad comes into contact with the object to be polished from above.

Further, a semiconductor device manufacturing method using the polishing apparatus configured as described above for polishing a surface of a semiconductor wafer (object to be polished) is constituted. like this PC orchid recommendation 150

4 According to the manufacturing method, a high-precision semiconductor device can be manufactured with a high throughput and a high yield, so that a low-cost, high-quality semiconductor device can be manufactured. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view schematically showing a configuration of a CMP apparatus which is an embodiment of a polishing apparatus according to the present invention.

FIG. 2 is a partially enlarged sectional view of the CMP device shown in FIG.

FIG. 3 is a diagram schematically showing an example of a conventional CMP device.

FIG. 4 is a flowchart showing an example of the semiconductor device manufacturing method according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view schematically showing a configuration of a CMP apparatus 10 which is an embodiment of a polishing apparatus according to the present invention, and FIG. 2 is a cross-sectional view showing the CMP apparatus 10 in a partially enlarged manner. is there. The CMP apparatus 10 includes a surface plate 20 for holding a semiconductor substrate 1 to be polished in a substantially horizontal posture, and a polishing surface (here, an upper surface) of the semiconductor substrate 1 held on the surface plate 20. A polishing head 30 having a polishing pad 36 attached to the opposing surface and a polishing head holder 40 for rotatably holding the polishing head 30 around a vertical axis are mounted on a frame (not shown). The apparatus includes an installed apparatus main body, and a slurry supply mechanism 50 and an additive liquid supply mechanism 60 described in detail later.

The surface plate 20 is attached to the upper end of a rotating column 21 extending substantially vertically. When the rotating column rotates around an axis, it rotates in a plane perpendicular to this axis (almost in a horizontal plane). I have. On the upper surface of the surface plate 20, a suction chuck (not shown) The lower surface side of the semiconductor substrate 1 to be polished can be sucked and held.

The polishing head 30 is composed of a rotating body 31 composed of a body 31a and a disk 31b formed below the body 31a, and the lower surface of the disk 31b of the rotating body 31 (platen 2). And a polishing pad 36 attached to the surface of the semiconductor substrate 1 held at 0 (the surface facing the surface to be polished). The body 3 1a of the rotator 3 1 has a hollow portion opened on the side opposite to the side on which the disk portion 3 1b (polishing pad 36) is provided, that is, an upper opening (hereinafter, this hollow portion is referred to as a mixing tank 3). 2) is formed. The lower surface of the disk portion 3 1b is flattened with high precision, so that the polishing pad 36 can be attached in a completely flat state. The polishing pad 36 is made of a nonwoven fabric, urethane or the like as a raw material, and is formed into a thin disk shape having substantially the same diameter as the disk portion 31 b of the rotating body 31. Since the polishing pad 36 is a consumable item, it can be detachably attached to the lower surface of the disc portion 31b with an adhesive or a double-sided tape.

The polishing head holder 40 can be three-dimensionally moved with respect to a frame (described above; not shown) via a plurality of stages whose movement can be controlled by a plurality of motors (not shown). As shown in the figure, the structure includes an extended portion 41 extending vertically downward, and a bearing 43 provided on the outer periphery of the extended portion 41. The extending portion 41 enters the mixing tank 32 formed in the rotating body 31 of the polishing head 30 from above from above, and the entire polishing head 30 rotates around the vertical axis through the bearing 43. It is rotatably supported.

A driven gear 37 is provided on the outer peripheral surface of the body 3 lb of the rotating body 31 of the polishing head 30, and is always engaged with a driving gear 39 driven by the motor 38. Therefore, by rotating the motor 38, its rotational power is transmitted from the drive gear 39 to the driven gear 37, and the entire polishing head 30 can be rotated around the vertical axis. As shown in FIG. 2, the first liquid flow extending in the vertical direction and having an outlet formed on the side surface of the extending portion 41 is inside the extending portion 41 of the polishing head holder 40. A channel 44 and a second liquid channel 45 are provided. An outwardly projecting holder-side stirring section 42 is formed on the outer periphery of the lower end of the extension section 41, and a projection protruding inward of the mixing tank 32 is formed on the inner wall of the mixing tank 32. A mixing tank-side stirring section 33 is formed. Further, inside the rotating body 31 of the polishing head 30, a mixed liquid supply pipe extending downward from the mixing tank 32 and opening at a plurality of positions near and around the rotation center position of the polishing pad 36. 3 4 are formed.

The slurry supply mechanism 50 includes a slurry storage tank 51 storing a slurry as a polishing liquid containing ceria particles, and a polishing head holder 40 having one end located in the slurry storage tank 51 and the other end. A slurry supply pipe 52 screwed into the upper opening of the first liquid flow path 44 formed inside the slurry supply pipe 52, and a slurry storage tank 51 provided in the middle of the slurry supply pipe 52 And a first pump 53 for pumping the slurry therein into the first liquid flow path 44. Further, the additive liquid supply mechanism 60 includes an additive liquid storage tank 61 storing an additive liquid (chemical liquid) used by being mixed with the slurry, and one end located in the additive liquid storage tank 61 and the other end disposed therein. An additive liquid supply pipe 62 screwed into and connected to the upper opening of a second liquid flow path 45 formed inside the polishing head holder 40, and in the middle of the additive liquid supply pipe 62. And a second pump 63 for pumping the additive liquid in the additive liquid storage tank 61 into the second liquid flow path 45. Here, both the slurry supply pipe 52 and the additive liquid supply pipe 62 are made of a flexible hose (for example, a rubber hose) having a small inner diameter, and the polishing head holder 40 is moved three-dimensionally. Can be flexed freely following this.

In order to perform flattening and polishing of a semiconductor substrate using the CMP apparatus 10 having such a configuration, first, the semiconductor substrate 1 (for example, a silicon wafer) to be polished is adsorbed on the upper surface of the surface plate 20. As a result, the polished surface of the semiconductor substrate 1 faces upward. As a result, the platen is held on the platen 20. It is preferable that the semiconductor substrate 1 is installed so that the center thereof coincides with the rotation center of the platen 20. When the semiconductor substrate 1 is held on the surface plate 20, the surface plate 20 is rotated together with the semiconductor substrate 1 in a horizontal plane. Then, the polishing head 30 is operated to rotate the polishing head 30 around the vertical axis (the polishing pad 36 also rotates in the horizontal plane), and the polishing head holder 40 is lowered. Then, the polishing pad 36 is brought into contact with the surface to be polished of the semiconductor substrate 1 from above. When the polishing pad 36 comes into contact with the surface to be polished of the semiconductor substrate 1 and polishing of the semiconductor substrate 1 starts, the polishing head holder 40 is moved in a direction parallel to the contact surface between the semiconductor substrate 1 and the polishing pad 36. (Here, in the horizontal direction) to polish the entire surface to be polished.

Immediately before the polishing of the semiconductor substrate 1 is started, a mixed liquid of the slurry and the additive liquid is supplied onto the surface of the semiconductor substrate 1 to be polished. This mixed liquid is supplied by operating the first pump 53 to supply the slurry in the slurry tank 51 to the first liquid flow in the slurry supply pipe 52 and the polishing head holder 40. While supplying the mixture from the channel 4 4 into the mixing tank 32, the second pump 63 is operated to supply the additive liquid in the additive liquid tank 61 with the additive liquid supply pipe 62 and the polishing head holder 40. This is performed by supplying the mixture from the second liquid flow path 45 into the mixing tank 32. Thus, the slurry supplied by the slurry supply mechanism 50 and the additive liquid supplied by the additive liquid supply mechanism 60 are mixed in the mixing tank 32, and the rotating body 4 of the polishing head 40 is mixed. The outside of the polishing pad 36 (that is, the lower surface of the polishing pad 36) from the mixed liquid supply pipe 34 provided in the vicinity of the rotation center position of the polishing pad 36 through the mixed liquid supply pipe 34 and the openings located at a plurality of positions around the polishing pad 36. ). The slurry in the slurry tank 32 must be constantly stirred so that the solid component is separated from the liquid component and does not precipitate in the tank. In this way, the surface to be polished of the semiconductor substrate 1 held on the surface plate 20 receives the supply of the mixed liquid of the slurry and the additive liquid, while rotating the semiconductor substrate 1 itself and the polishing head 30. Rotation and oscillating movement (ie polishing pad 36) Are polished uniformly, and the surface to be polished of the semiconductor substrate 1 is flattened with high precision. If the above polishing is continued, the polishing pad 36 gradually degrades and the polishing characteristics change (deteriorate). Therefore, the polishing pad 36 is recovered at regular intervals by using a conditioner (not shown) ( Need to be sharpened).

As described above, according to the present CMP apparatus 10, the slurry supplied by the slurry supply mechanism 50 and the additive liquid supplied by the additive liquid supply mechanism 60 are both mixed by the hollow mixing head provided inside the polishing head 30. The mixed liquid of the slurry and the additive liquid supplied to the mixing tank 32 is supplied to the mixing tank 32, and extends from the mixing tank 32 to the polishing head 40 to be positioned at the rotation center of the polishing pad 36. The slurry and additive liquid are supplied to the outside (the lower surface) of the polishing pad 36 from the mixed liquid supply pipe 34 opened in the vicinity, so that the slurry and the additive liquid are supplied immediately before being supplied to the surface to be polished of the semiconductor substrate 1. Will be mixed. Therefore, the effect of the additive liquid is sufficiently exhibited as compared with the conventional CMP apparatus, and the polishing accuracy of the substrate can be improved. Also, the mixed liquid of the slurry and the additive liquid mixed in the mixing tank 32 scatters radially due to the centrifugal force generated by the rotation of the polishing head 30 after jumping out of the polishing pad 36. In the CMP apparatus 10, the mixed liquid supply path 34, which is a path for the mixed liquid in the polishing head 30, is opened near the center of the polishing pad 36, so that the mixed liquid is coated on the semiconductor substrate 1. It is possible to cover the entire area of the polished surface.

Further, in the present CMP apparatus 10, the extension 41 of the polishing head holder 40 is located in the mixing tank 32 of the polishing head 30, and the polishing head 30 is Since the polishing head 30 is rotating, the extended portion 41 relatively rotates around the axis in the mixing tank 32 because the polishing head 30 is rotating. Thus, the slurry and the additive liquid in the mixing tank 32 are effectively stirred by the extension portion 41. In addition, in the present CMP apparatus 10, since the holding-member-side stirring section 42 having a protruding shape is formed on the outer periphery of the extension section 41 as described above, the slurry and the additive liquid are formed. 3150

The mixed solution of No. 9 is efficiently and uniformly mixed. Further, since the mixing tank side stirring section 33 having a protruding shape is also formed on the inner wall of the mixing tank 32, mixing of the mixed liquid is more effectively performed. In addition, the holding body side stirring section 42 and the mixing tank side stirring section 33 are not limited to the above-mentioned protrusion-shaped ones, and may be spiral groove-shaped ones.

Here, the rotation of the extension section 41 in the mixing tank 32 is relatively obtained by the rotation of the polishing head 30. Since no other power is used, the configuration of the stirring mechanism is simplified. There is an advantage that it becomes. It is also possible to adopt a configuration in which an independent stirring mechanism for mixing the slurry and the additive liquid is provided in the mixing tank 32.However, in this case, a power source for rotating the stirring member is separately required. The configuration becomes more complicated than the CMP apparatus 10.

Although the preferred embodiment of the present invention has been described above, the scope of the present invention is not limited to the above. For example, in the embodiment described above, the surface plate holds the semiconductor substrate so that the surface to be polished faces upward, and the polishing pad comes into contact with the surface to be polished (upper surface) of the semiconductor substrate from above. Conversely, the surface plate may hold the semiconductor substrate so that the surface to be polished faces downward, and the polishing pad may contact the surface to be polished (lower surface) of the semiconductor substrate from below. . However, in such a configuration, the slurry and the additive liquid are polished through the two liquid flow paths 44, 45 in the polishing head holder 40 and the mixed liquid supply path 34 in the polishing head 30. To supply the outside of the pad 36, a strong pumping force against the gravity is required.

Further, in both of the above embodiments, in addition to rotating the polishing head around the vertical axis, the surface plate holding the semiconductor substrate is also rotated, but in order to polish the polished surface of the semiconductor substrate, Since the semiconductor substrate and the polishing head (polishing pad) only need to move relatively, the surface plate does not necessarily have to rotate. Further, as the slurry to be used, alumina, silica or the like can be used in addition to ceria. Further, the present invention is applicable to a case where a plurality of kinds of additives are mixed and used in a slurry. Applicable. ,

Next, an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described. FIG. 4 is a flowchart showing a semiconductor device manufacturing process. When the semiconductor manufacturing process is started, first, in step S200, an appropriate processing step is selected from the following steps S201 to S204, and the process proceeds to any one of the steps. Here, step S201 is an oxidation step of oxidizing the surface of the wafer. Step S202 is a CVD step of forming an insulating film or a dielectric film on the wafer surface by CVD or the like. Step S203 is an electrode forming step of forming electrodes on the wafer by vapor deposition or the like. Step S204 is an ion implantation step of implanting ions into the wafer.

After the CVD step (S202) or the electrode forming step (S203), the process proceeds to step S205. Step S205 is a CMP step. In the CMP step, the polishing apparatus according to the present invention performs planarization of an interlayer insulating film, polishing of a metal film on the surface of a semiconductor device, formation of a damascene by polishing of a dielectric film, and the like.

After the CMP step (S205) or the oxidation step (S2), the process proceeds to step S206. Step S206 is about the same as photolithography. In this process, a resist is applied to the wafer, a circuit pattern is printed on the wafer by exposure using an exposure apparatus, and the exposed wafer is developed. Further, the next step S2 • 7 is an etching step in which portions other than the developed resist image are etched away, the resist is stripped off, and the unnecessary resist after etching is removed.

Next, in step S208, it is determined whether or not all necessary processes have been completed. If not, the process returns to step S200, and the previous steps are repeated to form a circuit pattern on the wafer. . If it is determined in step S208 that all the processes have been completed, the process ends. In the semiconductor device manufacturing method according to the present invention, since the polishing apparatus according to the present invention is used in the CMP process, the throughput of the CMP process is improved. Thus, there is an effect that a semiconductor device can be manufactured at a lower cost than a conventional semiconductor device manufacturing method. The polishing apparatus according to the present invention may be used in a CMP step of a semiconductor device manufacturing process other than the semiconductor device manufacturing process. In addition, a semiconductor device manufactured by the semiconductor device manufacturing method according to the present invention is manufactured at a high throughput, so that it is a low-cost semiconductor device.

As described above, according to the polishing apparatus of the present invention, the slurry and the additive liquid are mixed immediately before being supplied to the surface of the object to be polished. Therefore, the effect of the additive liquid is sufficiently exhibited as compared with the conventional polishing apparatus, and the polishing accuracy of the object to be polished can be improved. Further, after the mixed liquid of the mixed slurry and the additive liquid jumps out of the polishing pad, it is scattered radially by centrifugal force due to the rotation of the polishing head. Since the mixed liquid supply path, which is the path for the mixed liquid, is open near the center of the polishing pad, the mixed liquid can be spread over the entire surface of the surface of the object to be polished.

In addition, a semiconductor device manufacturing method is configured by using the polishing apparatus configured as described above in a step of polishing a surface of a semiconductor wafer, thereby manufacturing a high-accuracy semiconductor device with a high throughput and a high yield. Therefore, a high-quality semiconductor device can be manufactured at low cost. In addition, a high-quality semiconductor device can be provided at low cost.

Claims

Scope of demand

1. A surface plate for holding an object to be polished, and a polishing head having a polishing pad attached to a surface opposite to a surface to be polished of the object to be polished held on the surface plate, A polishing apparatus for polishing a surface to be polished by bringing a polishing pad into contact with the surface to be polished of the object to be polished,

A slurry supply mechanism for supplying slurry to the polishing head,

An additive liquid supply mechanism for supplying an additive liquid to be added to the slurry to the polishing head;

The slurry is provided inside the polishing head, and the slurry supplied from the slurry supply mechanism and the additive liquid supplied from the additive liquid supply mechanism are mixed and positioned near the rotation center position of the polishing pad. A polishing apparatus, comprising: a mixed liquid supply section that supplies the mixture to the outside of the polishing pad through an opening.

2. The polishing head is rotatably held by a polishing head holder,

2. The polishing apparatus according to claim 1, wherein a stirring member provided on one of the polishing head and the polishing head holder is located in the mixed liquid supply unit.

3. The polishing apparatus according to claim 2, wherein the stirring member has a shape of a protrusion or a spiral groove.

4. The polishing head is rotatably held by a polishing head holder,

The mixed liquid supply unit is formed by a space interposed between the polishing head and the polishing head holding pair, and at least a part of an inner wall of the polishing head and the polishing head holder forming the space. With a protrusion or spiral groove 2. The polishing apparatus according to claim 1, further comprising a stirring member.

5. The platen holds the object to be polished so that the surface to be polished faces upward, and the polishing pad comes into contact with the object to be polished from above. Item 4. The polishing apparatus according to Item 1.

6. The polishing apparatus according to claim 1, wherein the object to be polished is a semiconductor wafer.

7. A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing apparatus according to claim 6.