US20080064308A1

US20080064308A1 - Polishing apparatus and manufacturing method of an electronic apparatus

Info

Publication number: US20080064308A1
Application number: US11/653,953
Authority: US
Inventors: Naoki Idani
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Semiconductor Ltd
Priority date: 2006-09-08
Filing date: 2007-01-17
Publication date: 2008-03-13
Also published as: JP2008062355A

Abstract

A polishing apparatus that polishes a substrate to be processed includes a rotary polishing table carrying a polishing pad on a surface thereof, and a polishing head that urges the substrate to be processed against the polishing pad while rotating the substrate to be processed, wherein the polishing head holds the substrate to be processed by a retainer ring, the retainer ring includes: a resin ring formed of a resin and contacted with the polishing pad; and an upper part ring that holds the resin ring, at least first and second patterns of convex shape or concave shape are formed on a junction surface of the upper part ring where the upper part ring is contacted with the resin ring, at least third and fourth patterns of concave shape or convex shape are formed on a junction surface of the resin ring where the resin ring makes contact with the upper electrode, in a manner complementary to the patterns of the convex shape or concave shape formed on the junction surface of the upper electrode.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on Japanese priority application No.2006-244305 filed on Sep. 8, 2006, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to manufacturing of electronic apparatuses and more particularly to a chemical mechanical polishing apparatus used for manufacturing of such an electronic apparatus.
The technology of chemical mechanical polishing (CMP) has been used extensively for forming Cu multilayer interconnection structure by a damascene process or dual damascene process. On the other hand, because of the capability of providing near ideal flat surface in the processed surface, chemical mechanical polishing process provides a particularly advantageous effect when used with a photolithographic process that includes a high resolution exposure process and hence characterized by shallow focal depth. Thus, chemical mechanical polishing process is used extensively in these days as the technology indispensable for the production of semiconductor integrated circuit devices of high integration density or for the production of high resolution display devices.

Patent Reference 1

Japanese Laid-Open Patent Application 2005-34959 Official Gazette

Patent Reference 2

Japanese Laid-Open Patent Application 2000-301452 Official Gazette

SUMMARY OF THE INVENTION

FIG. 1 shows the construction of a polishing apparatus 100 according to a related art of the present invention.
Referring to FIG. 1, the polishing apparatus 100 has a construction of using a polishing pad 101 fixed upon a rotating polishing table 102, and a substrate 103 such as a wafer to be processed is urged against the polishing pad 101 covering the surface of the rotating polishing table 102 by using a polishing head 104 that urges the substrate 103 against the polishing pad 101 with a predetermined pressure while rotating the substrate 103.
Further, with the polishing apparatus 100 of FIG. 1, slurry 106 is supplied upon the polishing pad 101 from a supply nozzle 105 in the form of liquid, wherein the slurry causes a chemical reaction with the surface of the substrate to be processed at the part where the polishing pad 101 makes a contact with the substrate 103. Thereby, the reaction product formed as a result of the reaction is removed by the mechanical action of the abrasive particles contained in the slurry or by the mechanical action of the polishing pad. There can also be a case with such a chemical mechanical polishing process in which the slurry does not containing abrasive particles.
Further, in order to maintain the fresh surface state of the polishing pad 101, there is provided a roughening device 107 on the polishing table 102 at a location different from the location where the polishing head 104 is provided.
FIG. 2 shows the details of the polishing head 104.
Referring to FIG. 2, the polishing head 104 includes a membrane 121 that urges the substrate 103 to be processed against the polishing pad 101 with pressure, wherein the membrane 121 and the substrate 103 are held by a retainer ring 122. The retainer ring 122 not only holds the membrane 121 and the substrate 103 but also functions to improve the in-plane distribution of polishing as it is urged against the polishing pad 101.
FIG. 3 shows the details of the retainer ring 122 of the FIG. 2.
Referring to FIG. 3, the retainer ring 122 is formed of an upper part ring 122 a of a metal member such as stainless steel and a resin ring 122 b formed under the upper part ring 122 a and is urged against the polishing pad 101. It should be noted that the resin ring 122 b is adhered to the upper part ring 122 a by an adhesives at a junction surface 122 c.
Meanwhile, with recent chemical mechanical polishing apparatuses, there is an increasing opportunity of polishing a wafer of 30 cm diameter in the prospect of improved productivity of electronic apparatuses. However, in the case of polishing a wafer of such a large diameter, it was discovered that there occurs, in some cases, a rupture at the junction surface 122 c.
Further, in the case of the retainer ring of the type in which the resin ring 122 b and the upper part ring 122 a are fixed with each other by way of screws, too, it was discovered that such a rupture occurs at the junction surface in the vicinity of the screwed parts.
When there occurs a rupture at such a junction surface between the resin ring 122 b and the upper part ring 122 a, not only the polishing apparatus is damaged, but there is also caused a deterioration of yield in the polishing process by the fragments falling upon the polishing pad 101.
It is believed that such a rupture between the resin ring 122 b and the upper part ring 122 a is caused as a result of increase of the stress applied to the resin ring 122 b as a result of increase of friction between the polishing pad and the retainer ring particularly at the peripheral part of the retainer ring, while such increase of friction becomes conspicuous when the diameter of the substrate 103 to be processed is increased.
Thereupon, it may be conceivable that such a rupture between the resin ring 122 b and the upper part ring 122 a may be avoided by forming the whole retainer ring 122 by a resin. However, even in such a case of the retainer ring of unitary resin construction, there is a need of connecting the resin ring to a metal member constituting a part of the polishing head 104 at some location, and thus, this problem of rupture at the connection part cannot be avoided in any of the case of achieving the connection by an adhesive and the case of achieving the connection by screws.
The present invention proposes a polishing apparatus that polishes a substrate to be processed, comprising:
a rotary polishing table carrying a polishing pad on a surface thereof; and
a polishing head that urges said substrate to be processed against said polishing pad while rotating said substrate to be processed,
wherein said polishing head holds said substrate to be processed by a retainer ring,
said retainer ring comprising: a resin ring formed of a resin and contacted with said polishing pad; and
an upper part ring that holds said resin ring,
at least first and second patterns of convex shape or concave shape being formed on a junction surface of said upper part ring where said upper part ring is contacted with said resin ring,
at least third and fourth patterns of concave shape or convex shape being formed on a junction surface of said resin ring where said resin ring makes contact with said upper electrode, in a manner complementary to the said patterns of said convex shape or concave shape formed on said junction surface of said upper electrode.
Further, the present invention provides a manufacturing method of an electronic apparatus using such a polishing apparatus.
Thus, by forming at least the first and second patterns of convex or concave shape on the junction surface of the upper ring and further by forming at least the third and fourth patterns of convex or concave shape on the junction surface of the resin ring in complementary manner to the first and second patterns at the time of joining the upper ring and the resin ring constituting the retainer ring, it becomes possible to avoid damaging of the junction part between the resin ring and the upper ring, even when a large stress is applied to the resin ring, and it becomes possible to conduct the desired polishing process efficiently and with high yield.
Other objects and further features of the present invention will become apparent from the following detailed description when read in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the construction of a polishing apparatus according to a related art of the present invention;

FIG. 2 is a diagram showing the construction of a polishing head used with the polishing apparatus of FIG. 1;

FIG. 3 is a diagram showing the construction of a retainer ring used with the polishing head of FIG. 2;

FIG. 4 is a diagram showing the construction of a polishing apparatus according to a first embodiment of the present invention;

FIG. 5 is a diagram showing construction of a polishing head used with the polishing apparatus of FIG. 4;

FIG. 6 is a diagram showing the construction of a retainer ring used the polishing head of FIG. 5;

FIGS. 7A and 7B are diagrams showing the construction of an upper part ring of the retainer ring of FIG. 6 respectively in a plan view and cross-sectional view;

FIGS. 8A and 8B are diagrams showing the construction of a resin ring of the retainer ring of FIG. 6 respectively in a plan view and a cross-sectional view;

FIGS. 9A and 9B are diagrams showing a connection of the upper part ring and the resin ring of FIGS. 7 and 8;

FIGS. 10A and 10B are diagrams showing a modification of the retainer ring of FIG. 6;

FIGS. 11A and 11B are diagrams showing a different modification of the retainer ring of FIG. 6;

FIGS. 12A and 12B are diagrams showing a connection of the upper part ring and the resin ring of FIGS. 11A and 11B; and

FIGS. 13A-13D are diagrams showing the fabrication process of a semiconductor device according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

FIG. 4 shows the construction of a polishing apparatus 10 according to a first embodiment of the present invention.
Referring to FIG. 1, the polishing apparatus 10 has a construction in which a polishing pad 11 is fixed upon a rotating polishing table 12, and a substrate 13 such as a wafer to be processed is urged against the surface of the polishing table 12 by a rotating polishing head 14 with a predetermined pressure.
Further, with the polishing apparatus 10 of FIG. 4, slurry 16 is supplied upon the polishing pad 11 from a supply nozzle 15 in the form of liquid, wherein the slurry causes a chemical reaction with the surface of the substrate to be processed at the part where the polishing pad 11 makes a contact with the substrate 13 to be processed. Thereby, the reaction product formed as a result of the reaction is removed by the mechanical action of the abrasive particles in the slurry or by the mechanical action of the polishing pad 11. There can also be a case with such a chemical mechanical polishing process in which slurry not containing abrasive particles is used.
Further, in order to maintain the fresh surface state of the polishing pad 11, there is provided a roughening device 17 on the polishing table 12 at a location different from the location where the polishing head 14 is provided.
Thus, with the polishing apparatus of FIG. 4, the polishing head 14 is urged against the polishing pad 11 with a predetermined pressure, and chemical mechanical polishing is applied to the surface of the substrate 13 to be processed by dripping the slurry 16 while rotating the polishing head 14 and the polishing table 12 with respective rotational speeds.
With the polishing apparatus 10 of FIG. 4, not only the silicon wafer of conventional diameter of 20 cm but also the silicon wafer of larger diameter of 30 cm or more can be polished as the substrate 13, and thus, the polishing head 14 can hold thereon such a large diameter semiconductor wafer.
It should be noted that the above polishing condition, the slurry and the polishing pad 11 can be changed as necessary according to the nature of the film to be polished on the substrate 13.
FIG. 5 shows the details of the polishing head 14.
Referring to FIG. 5, the polishing head 14 includes a membrane 21 that urges the substrate 13 to be processed against the polishing pad 11, wherein the membrane 21 and the substrate 13 are held by the retainer ring 22. It should be noted that the retainer ring 22 not only holds the membrane 21 and the substrate 13 to be processed thereon but it is possible to improve the in-plane distribution of the polishing by being urged against the polishing pad 11.
FIG. 6 shows the details of the retainer ring 22 of the FIG. 2.
Referring to FIG. 6, the retainer ring 22 is formed of an upper part ring 22 a of a metal member such as stainless steel and a resin ring 22 b of a resin such as polyether ether ketone (PEEK) formed under the upper ring 22 a such that the resin ring 22 b is urged against the polishing pad 11, wherein the resin ring 22 b is adhered to the upper part ring 22 a by an adhesive at a junction surface 22 c.
FIG. 7A shows the upper part ring 22 a as viewed from a lower part in a plan view, while FIG. 7B shows the upper part ring 22 a in a cross-sectional view taken along a line A-A in FIG. 7A.
Referring to FIGS. 7A and 7B, the bottom surface 22 c 1 of the upper part ring 22 a forms one part of the junction surface 22 c of FIG. 6, wherein the bottom surface 22 c 1 is formed with a first pattern 23 a 1 of a groove that goes around the upper part ring 22 a and a second pattern 23 a 2 of plural grooves 23 a 2 each formed in a radial direction.
FIG. 8A shows the resin ring 22 b in a plan view as viewed from an upward direction, while FIG. 8B shows the resin ring 22 b in a cross-sectional view taken along a line B-B′ of FIG. 8A.
Referring to FIGS. 8A and 8B, the upper surface 22 c 2 of the resin ring 22 b forms the other part of the junction surface 22 c of FIG. 6, wherein it can be seen that there are formed a first pattern 23 b 1 of a convex part that goes around the resin ring 22 b and a second pattern 23 b 2 of plural convex parts each formed in a radial direction.
The convex part 23 b 1 is formed with a complementary shape corresponding to the groove 23 a 1, while the convex parts 23 b 2 are formed with a correspondingly complementary shape of the grooves 23 a 2. Thus, in the case the upper part ring 22 a and the resin ring 22 b are coupled with each other as shown in FIG. 6, the convex part 23 b 1 engages with to the groove 23 a 1 as shown in the cross-sectional view of FIG. 9A. Similarly, the convex parts 23 b 2 engage with respective, corresponding grooves 23 a 2 although not illustrated.
Thus, by fixing the upper part ring 22 a and the resin ring 22 b with each other in such a mutually engaged state by an adhesive in the retainer ring 22 of FIG. 6, the stress acting upon the resin ring 22 b is distributed to the convex parts 23 b 1 and 23 b 2 and to the grooves 23 a 1 and 23 a 2, and the problem of the upper part ring 22 a and resin ring 22 b causing rupture at the junction surface 22 c is avoided.
Further, as shown in FIG. 9B, the stress acting upon the resin ring 22 b is distributed to the convex parts 23 b 1 and 23 b 2 and further to the grooves 23 a 1 and 23 a 2 even in the case the coupling between the upper part ring 22 a and the resin ring 22 b is achieved by using screws 22 d, and the problem of the upper part ring 22 a and the resin ring 22 b causing rupture at the junction surface 22 c is avoided.
Furthermore, it is evident with the present embodiment that similar effects are attained in the case the grooves and the convex parts are formed oppositely to the upper ring 22 a and the resin ring 22 b, and thus, for the case when the grooves 23 a 1 and 23 a 2 are formed on the resin ring 22 b and the convex parts 22 b al and 22 b 2 are formed on the upper part ring 22 a.
FIGS. 10A and 10B show a modification of the first embodiment.
Referring to FIGS. 10A and 10B, the present embodiment eliminates the groove 23 a 1 extending in the circumferential direction from the junction surface 22 c 1 and the convex part 23 b 1 extending in the circumference direction from the junction surface 22 c 2, and thus, there are formed only the grooves 23 a 2 and the projections 23 b 2 extending in the radial direction.
Because the stress acting upon the junction surface 22 c by the friction acting to the polishing pad 11 works primarily in the circumferential direction, it is possible to suppress the rupture at the junction surface 22 c effectively even in such a case in which only the grooves 23 a 2 and the convex part 23 b 2 are formed to extend in the radial direction respectively on the upper part ring 22 a and the resin ring 22 b.
FIGS. 11A and 11B show another modification of the present embodiment.
Referring to FIGS. 11A and 11B, there are formed plural, mutually independent depressions 23 a on the junction surface 22 c 1 of the upper part ring 22 a, and there are formed plural, mutually independent convex part 23 bs at the junction surface 22 c 2 of the resin ring 22 b in a complementary manner to the depressions 23 a.
Thus, in the case of forming the retainer ring 22 by coupling the upper part ring 22 a and the resin ring 22 b as shown in FIG. 12A, the convex parts 23 b are accepted by the corresponding depressions 23 a and the resin ring 22 b is fixed firmly against the upper part ring 22 a in this state. Because the respective grooves 23 a and the respective convex parts 23 b form an isolated pattern in the present embodiment, the position of the resin ring 22 b is determined against the upper part ring 22 a in both the circumferential direction and the radial direction, and occurrence of rupture is suppressed at the junction surface 22 c even in the case a stress is applied in any of the circumferential direction and the radial direction.
In the present modification, too, the upper part ring 22 a and the resin ring 22 b may be fixed with each other by adhesives in the state of FIG. 12A, while these can be fixed also by using screws 23 d as shown in FIG. 12B.
Further, with the present modification, it is also possible to form the grooves 23 a on the resin ring 22 b and form the convex parts 23 b in the upper part ring 22 a also in the present modification.

Second Embodiment

FIGS. 13A-13D show a fabrication process of a semiconductor device according to a second embodiment of the present invention that uses the polishing apparatus 10 of FIG. 4.
Referring to FIG. 13A, a silicon substrate 41 of a silicon wafer of 30 cm diameter is formed with an SiN pattern 43 via a sacrificial oxide film 42 of a thermal oxide film, wherein there is formed a device isolation trench 41A in the silicon substrate 41 so as to define a predetermined device region 41B by a dry etching process while using the SiN pattern 43 as a mask.
Next in step of FIG. 13B, there is formed an SiO₂film 44 on the structure of the FIG. 13A by a CVD process so as to fill the device isolation trench 41A, and the silicon substrate 41, now in the state in which the structure of the FIG. 13B is formed, is held on the polishing head 14 of the polishing apparatus 10 as explained with reference to FIGS. 4-6 in the step of FIG. 13C as the substrate 13 to be processed, wherein the retainer ring 22 and the membrane 21 explained with reference to FIGS. 7-8 are used for holding the silicon substrate 41 on the polishing head 14.
Further, in the step of FIG. 14C, a commercially available polishing pad marketed for example by Rodel Nitta Company under the trade name IC1010 is used for the polishing pad 11, and polishing of the SiO₂film 44 is conducted by using a commercially available slurry marketed from Cabot Company under the trade name SS25, for the slurry with 1:1 dilution. Thereby, the polishing is conducted by rotating the polishing table 12 with a rotational speed of 110 rpm and rotating the polishing head 14 with a rotational speed of 98 rpm. During this polishing process, the polishing head 14 is urged against the polishing pad 11 by using the membrane 21 with a pressure of 280 gweight/cm². Thereby, polishing of the SiO₂film 44 is conducted until the SiN pattern 43 is exposed. In this case, the retainer ring 22 is urged against the polishing pad 11 with a pressure of about 700 g/cm².
In the step of FIG. 13C, the SiN film 43 functions as a polishing stopper, and a device isolation insulation film 44A of SiO₂is formed in correspondence to the device isolation trench 41A so as to define the device region 41B on the surface of the substrate 41.
Next, in the step of FIG. 14C, the SiN film 43 and also the sacrifice oxide film 42 are removed, and formation of the desired semiconductor device is conducted on the device region 41B thus exposed.
With the present embodiment, damaging of the retainer ring 22 is suppressed as a result of the use of the polishing apparatus 10, which in turn uses the retainer ring 22 explained previously, for the chemical mechanical polishing process of FIG. 13C, even in the case that the substrate 13 to be processed is a semiconductor wafer of large diameter, and it becomes possible to improve the efficiency and yield at the time of production of the semiconductor device.
While the present invention has been explained for preferred embodiments, the present invention is by no means limited to the embodiments described heretofore, but various variations and modifications may be made without departing from the scope of the invention.

Claims

1. A polishing apparatus that polishes a substrate to be processed, comprising:

a rotary polishing table carrying a polishing pad on a surface thereof; and

a polishing head that urges said substrate to be processed against said polishing pad while rotating said substrate to be processed,

wherein said polishing head holds said substrate to be processed by a retainer ring,

said retainer ring comprising: a resin ring formed of a resin and contacted with said polishing pad; and

an upper part ring that holds said resin ring,

at least first and second patterns of convex shape or concave shape being formed on a junction surface of said upper part ring where said upper part ring is contacted with said resin ring,

at least third and fourth patterns of concave shape or convex shape being formed on a junction surface of said resin ring where said resin ring makes contact with said upper electrode, in a manner complementary to the said patterns of said convex shape or concave shape formed on said junction surface of said upper electrode.

2. The polishing apparatus as claimed in claim 1, wherein said first and second patterns are formed on said junction surface of said upper ring respectively in a circumferential direction and in a radial direction, said third and fourth patterns are formed on said junction surface of said resin ring respectively in said circumferential direction and said radial direction.

3. The polishing apparatus as claimed in claim 2, wherein said first pattern is formed on said junction surface of said upper ring so as to go around continuously along said upper ring, and wherein said third pattern is formed on said junction surface of said resin ring so as to go around contiguously along said resin ring.

4. The polishing apparatus as claimed in claim 1, wherein said first and second patterns form plural pattern elements each extending on said junction surface of said upper ring in a radial direction, and wherein said third and fourth patterns form plural pattern elements each extending on said junction surface of said resin ring in a radial direction.

5. The polishing apparatus as claimed in claim 1, wherein said first and second patterns form isolated patterns on said junction surface of said upper part ring, and wherein said third and fourth patterns form isolated patterns on said junction surface of said resin ring.

6. The polishing apparatus as claimed in claim 1, wherein said resin ring and said upper part ring are connected with each other by adhering said respective junction surfaces by an adhesive.

7. The polishing apparatus as claimed in claim 1, wherein said resin ring and said upper part ring are connected with each other by screws.

8. A method for fabricating a semiconductor device, comprising a step of polishing a film formed on a substrate to be processed by using a polishing apparatus, said polishing apparatus comprising:

a rotary polishing table carrying a polishing pad on a surface thereof; and

an upper part ring that holds said resin ring,