RETAINER RING, POLISHING APPARATUS, AND MANUFACTURING METHOD OF SEMICONDUCTOR DEVICE
In accordance with an embodiment, a polishing apparatus includes a polishing table and a polishing head. A retainer ring is attached to a surface of the polishing head. The surface of the polishing head faces the polishing table. The retainer ring includes a ceramic material. The fracture toughness of the ceramic material is 4 MPa·m1/2 or more.
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2015-020854, filed on Feb. 5, 2015, the entire contents of which are incorporated herein by reference.
FIELDEmbodiments described herein relate generally to a retainer ring, a polishing apparatus, and a manufacturing method of a semiconductor device.
BACKGROUNDIn a manufacturing process of a semiconductor device, chemical mechanical polishing (hereinafter referred to as “CMP”) is used to flatten, for example, an insulating film, a metallic film, or a polycrystalline silicon film buried in a trench which is provided in a surface of a polishing object by patterning. A CMP apparatus generally holds the rear surface (the surface opposite to a polishing surface) of the polishing object by a polishing head to press the surface (polishing surface) of the polishing object onto a polishing pad to which slurry is supplied, and relatively rotate the polishing head and the polishing pad, thereby flattening the insulating film, the metallic film, or polycrystalline silicon buried in the trench in the surface of the polishing object.
The polishing head which holds the polishing object is provided with a mechanism which applies pressure to the rear surface of the polishing object, and a retainer ring which prevents the polishing object from protruding to outside of the polishing head during the relative rotation of the polishing head and the polishing pad.
The retainer ring as well as the polishing object is pressed onto the polishing pad. Therefore, if the fracture toughness is low, wear rapidly progresses due to the repetition of polishing, and the frequency of replacement increases, so that the costs of consumable materials increase, and time loss caused by replacement work is a problem.
Impact from the polishing object is also applied to the retainer ring. Therefore, partial wear occurs such that wear more significantly progresses on the side of the polishing object than on the side opposite to the polishing object. In this case, the outer peripheral part of the polishing object is excessively polished.
In the accompanying drawings:
In accordance with an embodiment, a polishing apparatus includes a polishing table and a polishing head. A retainer ring is attached to a surface of the polishing head. The surface of the polishing head faces the polishing table. The retainer ring includes a ceramic material, The fracture toughness of the ceramic material is 4 MPa·m1/2 or more.
Embodiments will now be explained with reference to the accompanying drawings, Like components are provided with like reference signs throughout the drawings and repeated descriptions thereof are appropriately omitted. It is to be noted that the accompanying drawings illustrate the invention and assist in the understanding of the illustration and that the shapes, dimensions, and ratios and so on in each of the drawings may be different in some parts from those in an actual apparatus.
First, a polishing apparatus according to one embodiment is described with reference to
A polishing apparatus 1 shown in
A polishing pad 8 is attached to the upper surface (the surface facing the polishing head 3) of the polishing table 2. The polishing table 2 is configured to be rotatable and drivable by a driver (not shown) including a motor.
The polishing head 3 is configured to be rotatable and drivable by a driver (not shown) including a motor. This polishing head 3 is configured to be able to press the upper surface (the surface facing the polishing head 3) of the polishing pad 8 with predetermined pressure while rotating, for example, a semiconductor wafer W (see
The diamond dresser 4 conditions the surface of the polishing pad 8. The diamond dresser 4 is rotated and driven by a driver (not shown) including a motor, and is configured to be pressed by the polishing pad 8.
The polishing solution supply opening 5, the pure water supply opening 6, and the cleaning solution supply opening 7 are configured to be able to respectively supply a polishing solution (e.g. slurry), pure water, and a cleaning solution onto the polishing pad 8 at predetermined flow volumes.
The specific structure of the polishing head 3 is described with reference to
The polishing head 3 includes circular-plate-shaped head body 10, a membrane 12, and a retainer ring 11 corresponding to one embodiment. The head body 10 is configured to be supported by an arm (not shown). The membrane 12 is held by the retainer ring 11 so as to contact the lower surface (the surface facing the polishing pad 8) of the head body 10. The retainer ring 11 is attached to the lower surface of the head body 10, and holds the semiconductor wafer W in such a manner that the surface of the semiconductor wafer W opposite to the polishing surface contacts the lower surface of the membrane 12.
The semiconductor wafer W thus held by the retainer ring 11 is pressed to the polishing pad 8 by the head body 10 and the membrane 12.
A schematic configuration of the retainer ring 11 is shown in a perspective view in
The outline of a manufacturing method of this retainer ring 11 is described with reference to
Specifically, a ceramic material (powder) is put into a rubber-state mold formed to adapt to the shape of a target retainer ring (step 1), and the mold is then inserted into a high-pressure container (step 2) and isotropically pressurized via a pressure medium (liquid) (step 3). As the ceramic material, for example, zirconia (ZrO2), alumina (Al2O3), silicon carbide (SiC), silicon nitride (SiN), yttria (Y2O3), and cordierite (2MgO·2Al2O3·5SiO2) can be used (see
A primary process to form a groove (not shown) of the retainer ring is then performed (step 4), and a sinter process is performed to eliminate holes in the ceramic material (step 5). Finally, a finish process is performed as a secondary process, and the retainer ring 11 is thereby obtained (step 6).
The degree of fracture toughness is a problem in the manufacture of the retainer ring. This is because if the retainer ring is manufactured by the use of a material having a fracture toughness of less than 4 MPa·m1/2, the retainer ring may break due to insufficient pressure during the CIP formation or may break from a slight crack or the like occurring during mechanical processing for forming the grooves in the primary process.
In contrast, when a material having a fracture toughness of 4 MPa·m1/2 or more is used to manufacture the retainer ring by the CIP formation method, it was confirmed that the retainer ring can be satisfactorily manufactured without breakage or the like.
In CMP, the polishing head 3 and the polishing pad 8 are relatively rotated to flatten the surface of the semiconductor wafer W. Therefore, force from the polishing pad 8 is applied to the retainer ring 11 as indicated by the arrow AR1 in
In an initial state of use of the retainer ring 11, rebounds from the polishing pad 8 equally occur inside and outside the retainer ring 11 as shown in
An example of this wafer edge excessive polishing state is shown in a graph of
The retainer ring 11 according to the present embodiment has a fracture toughness of 4 MPa·m1/2 or more, thus chipping in the inner surface of the retainer ring 11 is inhibited. Consequently, the occurrence of the partial wear can be inhibited.
Meanwhile, the impact by the (lateral) force during polishing which causes the semiconductor wafer W to protrude to the outside of the polishing head 3 is not only applied to the retainer ring 11 but also applied to the side of the semiconductor wafer W, and stress is repeatedly generated by collision between the semiconductor wafer W and the retainer ring 11. Therefore, if a retainer ring 11 manufactured by the use of a hard material is used, a chip CP2 may occur in the side surface of the semiconductor wafer W by receiving repetitive stress in the direction of the arrow AR3, as shown in
One index that indicates the hardness (the degree of the elastic modulus) of a material is the Young's modulus (the physicality value [GPa] that indicates the difficulty of deformation). Stronger impact is applied to the semiconductor wafer W in the case of materials that are less deformable, so that the degree of the impact applied to the semiconductor wafer W can be judged by the degree of the Young's modulus of the retainer ring 11.
The fracture toughness and Young's modulus of respective selectable ceramic materials are shown in a table of
The retainer ring according to at least one embodiment described above includes the ceramic material, so that the progress of wear can be inhibited.
In addition, the retainer ring according to at least one embodiment described above has a fracture toughness of 4 MPa·m1/2 or more, so that the progress of partial wear can be inhibited.
Furthermore, the retainer ring according to at least one embodiment described above has a Young's modulus is 400 GPa or less, so that it is possible to prevent the polishing object from being damaged.
The polishing apparatus 1 according to at least one embodiment described above includes the retainer ring including the ceramic material, so that the frequency of the replacement of the retainer ring decreases, the throughput of the polishing process improves, and the polishing object can be thus polished at low cost.
In addition, the polishing apparatus 1 according to at least one embodiment described above includes the retainer ring having a fracture toughness of 4 MPa·m1/2 or more, so that the polishing object can be polished without uneven polishing and without the chipping in the retainer ring.
Furthermore, the polishing apparatus 1 according to at least one embodiment described above includes the retainer ring having a Young's modulus of 400 GPa or less, so that it is possible to inhibit the polishing object from being damaged.
Next, a manufacturing method of a semiconductor device according to one embodiment is described. The manufacturing method according to the present embodiment includes a polishing process using the polishing apparatus 1 shown in
First, a semiconductor wafer W in which an insulating film, a metallic film, a polycrystalline silicon film, and others are formed by, for example, patterning is prepared.
The semiconductor wafer W is then brought into contact with the polishing pad 8 in such a manner that the polishing surface of the semiconductor wafer W faces the polishing pad 8 while the semiconductor wafer W is held by the polishing head 3.
The polishing table is then rotated, for example, in the direction of the arrow AR10 in
During polishing, the surface part of the semiconductor wafer W is returned to the initial state before polishing by the diamond dresser 4 in order to prevent the surface part of the polishing pad 8 from being worn or being clogged with abrasive grains included in an abrasive due to the polishing of the semiconductor wafer W.
The polishing pad 8 and the polishing head 3 are preferably rotated and driven together, from the perspective of eliminating the unevenness of the polishing amount of the semiconductor wafer W. When these portions are rotated and driven, the rotation direction of the polishing pad 8 and the rotation direction of the polishing head 3 are preferably the same as shown in
According to the manufacturing method of the semiconductor device in at least one embodiment described above, the substrate is polished by the use of the polishing apparatus 1 provided with the retainer ring 11 including the ceramic material, so that the costs of consumable materials are reduced, and the manufacturing costs of the semiconductor device can be reduced.
In addition, according to the manufacturing method of the semiconductor device in at least one embodiment described above, the substrate is polished by the use of the polishing apparatus 1 provided with the retainer ring 11 having a fracture toughness of 4 MPa·m1/2 or more, so that it is possible to prevent the excessive polishing of a substrate edge region resulting from the partial wear of the retainer ring. Consequently, the substrate can be accurately polished, so that it is possible to improve the yield of the semiconductor device.
Furthermore, according to the manufacturing method of the semiconductor device in at least one embodiment described above, the substrate is polished by the use of the polishing apparatus 1 provided with the retainer ring 11 having a, Young's modulus of 400 GPa or less, so that it is possible to prevent the substrate from being chipped, and improve the yield of the semiconductor device.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to emit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions, The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Claims
1. A retainer ring comprising:
- a ceramic material, the fracture toughness of the ceramic material being 4 MPa·m1/2 or more.
2. The retainer ring of claim 1,
- wherein the Young's modulus of the ceramic material is 400 GPa or less.
3. The retainer ring of claim 1,
- wherein the ceramic material comprises at least one of substances selected from the group consisting of zirconia (ZrO2), alumina (Al2O3), silicon carbide (SiC), silicon nitride (SiN), yttria (Y2O3), and cordierite (2MgO·2Al2O3·5SiO2).
4. A polishing apparatus comprising:
- a polishing table; and
- a polishing head with a retainer ring attached to a surface of the polishing head facing the polishing table,
- wherein the retainer ring comprises a ceramic material, and
- the fracture toughness of the ceramic material is 4 MPa,m1/2 or more.
5. The apparatus of claim 4,
- wherein the Young's modulus of the ceramic material is 400 GPa or less.
6. The apparatus of claim 4,
- wherein the ceramic material comprises at least one of substances selected from the group consisting of zirconia (ZrO2), alumina (Al2O3), silicon carbide (SiC), silicon nitride (SiN), yttria (Y2O3), and cordierite (2MgO·2Al2O35SiO2).
7. A manufacturing method of a semiconductor device, the method comprising
- rotating a polishing table to which a polishing pad is attached, and rotating a substrate held by a retainer ring attached to a polishing head while pressing the substrate to the polishing pad, thereby polishing the substrate,
- wherein the retainer ring comprises a ceramic material, and
- the fracture toughness of the ceramic material is 4 MPa·m1/2 or more.
8. The apparatus of claim 4,
- wherein the Young's modulus of the ceramic material is 400 GPa or less.
9. The apparatus of claim 4,
- wherein the ceramic material comprises at least one of substances selected from the group consisting of zirconia (ZrO2), alumina (Al2O3), silicon carbide (SiC), silicon nitride (SiN), yttria (Y2O3), and cordierite (2MgO·2Al2O3·5SiO2).
Type: Application
Filed: Sep 9, 2015
Publication Date: Aug 11, 2016
Inventors: Takahiko KAWASAKI (Nagoya), Yukiteru MATSUI (Nagoya), Kenji IWADE (Yokkaichi), Akifumi GAWASE (Kuwana)
Application Number: 14/848,897