Source: http://www.google.com/patents/US20020042243?dq=2040248
Timestamp: 2018-01-19 22:25:19
Document Index: 461272946

Matched Legal Cases: ['art.\n14', 'art.\n15', 'art 18', 'art 18', 'arts 32', 'art 32', 'art 32', 'art 31', 'art 32', 'arts 32', 'arts 32', 'art 32', 'art 32', 'art 32', 'art 31', 'art 32', 'arts 22', 'arts 32', 'art 32', 'arts 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'arts 33', 'art 22', 'art 22', 'art 22']

Patent US20020042243 - Polishing body, polishing apparatus, polishing apparatus adjustment method ... - Google Patents
After a hole is formed in a polishing pad, a transparent window plate is inserted into the hole. Here, a gap is left between the upper surface of the transparent window plate and the outermost surface constituting the working surface of the polishing pad. During polishing, the polishing head holding...http://www.google.com/patents/US20020042243?utm_source=gb-gplus-sharePatent US20020042243 - Polishing body, polishing apparatus, polishing apparatus adjustment method, polished film thickness or polishing endpoint measurement method, and semiconductor device manufacturing method
Publication number US20020042243 A1
Application number US 09/846,339
Also published as CN1150601C, CN1322374A, DE60035341D1, EP1176630A1, EP1176630A4, EP1176630B1, US6458014, WO2000060650A1
Publication number 09846339, 846339, US 2002/0042243 A1, US 2002/042243 A1, US 20020042243 A1, US 20020042243A1, US 2002042243 A1, US 2002042243A1, US-A1-20020042243, US-A1-2002042243, US2002/0042243A1, US2002/042243A1, US20020042243 A1, US20020042243A1, US2002042243 A1, US2002042243A1
Inventors Akira Ihsikawa, Tatsuya Senga, Akira Miyaji, Yoshijiro Ushio
Original Assignee Akira Ihsikawa, Tatsuya Senga, Akira Miyaji, Yoshijiro Ushio
US 20020042243 A1
After a hole is formed in a polishing pad, a transparent window plate is inserted into the hole. Here, a gap is left between the upper surface of the transparent window plate and the outermost surface constituting the working surface of the polishing pad. During polishing, the polishing head holding the wafer applies a load to the polishing pad by means of a load-applying mechanism, so that the polishing pad and transparent window plate are compressed. In this case, the system is arranged so that the gap remains constant, and so that a dimension equal to or greater than a standard value is maintained. Since the upper surface of the transparent window plate is recessed from the upper surface of the polishing pad, there is no scratching of the surface of the transparent window plate during dressing. Accordingly, the polishing pad has a long useful life.
1. A polishing body used in a polishing apparatus comprising:
a polishing head that holds an object of polishing, wherein the polishing apparatus polishes the object of polishing by causing relative motion between the polishing body and the object of polishing in a state in which a polishing agent is interposed between the polishing body and the object of polishing, wherein the polishing body comprises:
at least one opening part, which allows passage of measurement light that optically measures a surface that is being polished on the object of polishing, formed in the polishing body;
at least one window plate, that is transparent to at least the measurement light, positioned in the at least one opening part; and
a gap between an outermost surface of the polishing body and a surface of the at least one window plate on a side of the outermost surface in an unloaded state is adjusted so that the gap is greater than an amount of compressive deformation of the polishing body that occurs when a polishing load is applied.
2. The polishing body of claim 1, wherein a minimum value G of the gap between the outermost surface of the polishing body and the surfaces of the at least one window plate on the side of the outermost surface is such that 0 μm<G≦400 μm.
3. The polishing body of any of claim 1, wherein a minimum value G of the gap between the outermost surface of the polishing body and the surfaces of the at least one window plate on the side of the outermost surface is such that 10 μm<G≦200 μm.
4. The polishing body of claim 1, wherein the gap G between the outermost surface of the polishing body and the surfaces of the at least one window plate on the side of the outermost surface is a maximum value of G in cases where the gap G differs within one of a single opening part and between different opening parts is such that 0 μm<G≦90% of a thickness of the polishing body, and a thickness t of the window plate is a minimum value of the thickness t in cases where this thickness t differs within one of a single opening part and between different opening parts is such that t ≧10% of a thickness of the polishing body.
5. The polishing body of claim 1, wherein at least a surface of the at least one window plate located on a side of the object of polishing is coated with a hard coating.
6. The polishing body of claim 1, wherein a transmissivity of the at least one window plate with respect to the measurement light is 22% or greater.
7. A polishing body used in a polishing apparatus comprising:
at least one window plate, that is transparent to at least the measurement light, positioned in the at least one opening part, wherein the window plate comprises at least two plates comprising transparent materials; and
a gap between an outermost surface of the polishing body and a surface of the at least one window plate on a side of the outermost surface.
8. The polishing body of claim 7, wherein the at least one window plate comprises two plates of transparent materials that are laminated together, and among these plates of transparent materials, a compressive elastic modulus of the transparent material plate that is located on a side of the object of polishing is set at a value lower than a compressive elastic modulus of the transparent material plate that is located on an opposite side from the object of polishing.
9. The polishing body of claim 8, wherein the compressive elastic modulus e of the transparent material on the side of the object of polishing is such that 2.9×107 Pa ≦e≦1.47×109 Pa, and the compressive elastic modulus of the transparent material is substantially equal to the compressive elastic modulus of the polishing body.
10. The polishing body of claim 7, wherein a compressive elastic modulus e of the transparent material on a side of the object of polishing is such that 2.9×107 Pa ≦e≦1.47×109 Pa, and the compressive elastic modulus of the transparent material is substantially equal to the compressive elastic modulus of the polishing body.
11. The polishing body of claim 7, wherein a transmissivity of the at least one window plate with respect to the measurement light is 22% or greater.
12. A polishing body used in a polishing apparatus comprising:
at least one opening part, which is used to allow passage of measurement light that optically measures a surface that is being polished on the object of polishing, formed in the polishing body;
at least one window plate, that is transparent to the measurement light, positioned in the at least one opening part, wherein a surface of the at least one window plate on a side of the object of polishing is recessed with respect to a surface of the polishing body, with an amount of the recess being varied in one of a stepwise manner and a continuous manner; and
a gap between an outermost surface of the polishing body and the surface of the at least one window plate on a side of the outermost surface.
13. The polishing body of claim 12, wherein the polishing body has a plurality of the at least one opening part, and the amount of recess varies in a stepwise manner as a result of the amount of recess being different in each of the plurality of the at least one opening part.
14. The polishing body of claim 12, wherein the amount of recess varies in a stepwise manner as a result of the amount of recess being different in at least two portions within a same opening part.
15. The polishing body of claim 12, wherein the at least one window plate is a parallel flat-plate-form transparent plate, and the at least one window plate is inclined with respect to the surface of the polishing body, such that the amount of recess varies in a continuous manner.
16. The polishing body of claim 12, wherein at least a surface of the at least one window plate located on a side of the object of polishing is coated with a hard coating.
17. The polishing body of claim 12, wherein a transmissivity of the at least one window plate with respect to the measurement light is 22% or greater.
18. A polishing body used in a polishing apparatus comprising:
at least one opening part, which is used to allow passage of measurement light that optically measures a surface that is being polished on the object of polishing, formed in the polishing body; and
at least one window plate, that is transparent to the measurement light, positioned in the at least one opening part, wherein a surface of the at least one window plate on a side of the object of polishing is recessed with respect to a surface of the polishing body, and the at least one window plate is constructed from a plate material comprising a plurality of sheets of a transparent material that can be stripped away.
19. The polishing body of claim 18, wherein a transmissivity of the at least one window plate with respect to the measurement light is 22% or greater.
20. A polishing body comprising:
a material that is transparent to at least a measurement light in order to allow passage of the light used for optical measurement of the polished surface of the object of polishing.
a polishing head that holds an object of polishing, wherein the polishing apparatus polishes the object of polishing by causing relative motion between the polishing body and the object of polishing in a state in which a polishing agent is interposed between the polishing body and the object of polishing, wherein the polishing body is the polishing body of any one of claims 1, 7 and 12.
22. The polishing apparatus of claim 21, wherein the measurement light is projected onto the object of polishing from a light-projecting device via the at least one window plate and the at least one opening part, wherein the projected light is reflected by the object of polishing, and the reflected light passing through the at least one opening part and the at least one window plate is received by a light-receiving device, an intensity of the reflected light that is received during polishing is at least 1% of an intensity of the projected light.
23. The polishing apparatus of claim 21, wherein the at least one window plate comprises a resin having polishing characteristics comparable to polishing characteristics of the polishing body.
24. A method to adjust a gap between an outermost surface of a polishing body and a surface of at least one window plate on a side of the outermost surface in the polishing apparatus of claim 21, wherein the measurement light is directed onto the object of polishing from a light-projecting device via the at least one window plate and the at least one opening part and is reflected by the object of polishing, and the reflected light passing through the at least one opening part and the at least one window plate is received by a light-receiving device; wherein the polishing apparatus adjustment method comprises:
a stage in which the gap between the outermost surface of the polishing body and the surfaces of the at least one window plate on the side of the outermost surface is adjusted on a basis of a signal measured by the light-receiving device.
25. A method for measuring one of a thickness of a polished film and an endpoint of polishing in which polishing is performed using the polishing apparatus of claim 21, and one of the thickness of the polished film and the endpoint of polishing is measured using a light signal received by a light-receiving device; wherein a signal measured by a measurement means used to measure one of the polished film thickness and the polishing endpoint is not used in the measurement of one of the polished film thickness and the polishing endpoint in cases where the signal measured by the measurement means is equal to a signal that is measured beforehand and stored in memory.
a polishing head that holds an object of polishing;
a polishing body positioned on a platen, wherein the polishing apparatus polishes the object of polishing by causing relative motion between the polishing body and the object of polishing in a state in which a polishing agent is interposed between the polishing body and the object of polishing; wherein the polishing apparatus comprises:
at least one first opening part formed in the platen;
at least one second opening part formed in the polishing body;
a plurality of windows disposed to block at least portions of the at least one second opening part formed in the polishing body;
a device which measures a polished state by optically observing a polished surface of the object of polishing via the plurality of windows; and
a moving device which moves positions of the plurality of windows on the surface of the object of polishing, wherein the at least one second opening part formed in the polishing body and the at least one first opening part formed in the platen are superimposed, so that the plurality of windows are disposed on the platen via the moving device.
27. The polishing apparatus of claim 26, further comprising:
a device that senses a gap between surfaces of the plurality of windows on a side of the object of polishing and a polished surface of the object of polishing;
one of a device that senses conditions of wear of the polishing body, and a device that senses the gap and conditions of wear.
28. The polishing apparatus of claim 27, further comprising:
a control device that controls the gap between the surfaces of the plurality of windows on the side of the object of polishing and the polished surface of the object of polishing.
29. The polishing apparatus of claim 28, further comprising:
a function which predicts an amount of wear of the polishing body from polishing conditions, polishing time, dressing conditions and dressing time, and controls the gap between the surfaces of the plurality of windows on the side of the object of polishing and the polished surface of the object of polishing.
30. The polishing apparatus of claim 28, further comprising:
a function which controls the moving device so that the gap between the surfaces of the plurality of windows on the side of the object of polishing and the polished surface of the object of polishing is maintained at a constant value.
31. The polishing apparatus of claim 28, further comprising:
a function which controls the gap between the surfaces of the plurality of windows on the side of the object of polishing and the polished surface of the object of polishing in synchronization with rotation of the platen.
32. A semiconductor device manufacturing method which includes use of the apparatus of claim 21 in a manufacturing process.
33. A semiconductor device manufacturing method which includes use of the apparatus of claim 26 in a manufacturing process.
34. A semiconductor device manufacturing method which includes use of the method of claim 24 in a manufacturing process.
35. A semiconductor device manufacturing method which includes use of the method of claim 25 in a manufacturing process.
A chemical mechanical polishing or chemical mechanical planarization (hereafter referred to as “CMP”) technique is widely used as a method for planarizing the surfaces of such semiconductor devices. Currently, the CMP technique is the sole method that can be used to planarize the entire surface of a silicon wafer.
CMP was developed on the basis of silicon wafer mirror surface polishing methods. FIG. 2 is a schematic structural diagram of a polishing (planarization) apparatus used in CMP. This polishing apparatus is constructed from a polishing member 15, an object of polishing holding part (hereafter referred to as a “polishing head” in some instances) 16, and a polishing agent supply part 18. Furthermore, a silicon wafer 17 which is the object of polishing is attached to the polishing head 16, and the polishing agent supply part 18 supplies a polishing agent (slurry) 19. The polishing member 15 is formed by attaching a polishing body (hereafter referred to as a “polishing pad” in some instances) 21 to the surface of a platen 20.
The first aspect of the present invention is to solve the above-mentioned problems, and to provide a polishing body which is used in a polishing apparatus that is capable of measuring the polished state by means of light, namely a polishing body that does not cause instability in polishing, a polishing body which has a measurement window that does not require a complicated mechanism, a polishing body that does not suffer from problems such as scratching during dressing, etc., and a polishing body that does not cause instability in the detection of the polishing endpoint in situ, and a polishing apparatus which uses such polishing bodies.
In the present invention, the gap between the outermost surface of the polishing body and the surfaces of the window plates on the side of the outermost surface (hereafter referred to as the “upper surfaces” of the window plates in some instances) in an unloaded state is adjusted so that this gap is greater than the amount of compressive deformation of the polishing body that occurs when the polishing load is applied. Accordingly, even if the polishing body should contract as a result of compressive deformation when the polishing load is applied, the outermost surface of the polishing body will be closer to the object of polishing than the outermost surfaces of the window plates. Accordingly, even when the polishing load is applied, the window plates will not contact the object of polishing; consequently, scratching of the window plates can be prevented.
A fourth embodiment of the present invention which is used in order to achieve the first aspect of the invention is the second and third embodiments, which is further characterized by the fact that the compressive elastic modulus e of the transparent material on the side of the object of polishing (among the transparent materials) is such that 2.9×107Pa≦e≦1.47×109 Pa, and is more or less the same as the compressive elastic modulus of the polishing body.
[0082]FIGS. 1A and 1B show an example of a planarization technique used in a semiconductor process; the left side of the figures shows the state prior to planarization, while the right side of the figures shows the state following planarization.
[0083]FIG. 2 is a schematic structural diagram of a polishing (planarization) apparatus used in CMP.
[0084]FIG. 3 illustrates a first example of a polishing pad (polishing body) of the present invention.
[0086]FIGS. 5A and 5B illustrate a third example of a polishing pad (polishing body) of the present invention.
[0087]FIGS. 6A and 6B illustrate a fourth example of a polishing pad (polishing body) of the present invention.
[0088]FIGS. 7A and 7B illustrate a fifth example of a polishing pad (polishing body) of the present invention.
[0089]FIGS. 8A and 8B illustrate a sixth example of a polishing pad (polishing body) of the present invention.
[0090]FIG. 9 illustrates a first example of a polishing pad (polishing body) that constitutes an embodiment of the present invention.
[0091]FIG. 10 illustrates the shape of the V-shaped groove of the polishing pad shown in FIG. 9.
[0092]FIG. 11 shows an example of the variation in the residual film thickness observed during polishing.
[0093]FIG. 12 shows reflective spectra from the silicon wafer surface measured in situ at certain instants during polishing.
[0094]FIG. 13 is a diagram which shows the structure of an embodiment of the polishing body of the present invention which has window plates comprise a two-layer structure.
[0095]FIG. 14 shows a reflective spectrum from the silicon wafer surface measured in situ.
[0097]FIG. 16 shows a reflective spectrum observed during polishing.
[0098]FIG. 17 is a sectional view of the area in the vicinity of one of the opening parts in the platen of a polishing apparatus of the present invention.
[0099]FIGS. 18A and 18B show an outline of the area in the vicinity of the polishing body of a polishing apparatus.
[0100]FIG. 19 shows reflective spectra from the silicon wafer surface measured in situ at certain instants during polishing.
[0101]FIG. 20 illustrates the semiconductor device manufacturing process.
[0104]FIG. 3 is a diagram which is used to illustrate a first example of a polishing pad (polishing body) of the present invention. In the following figures, constituent elements that are the same as constituent elements shown in preceding figures are labeled with the same symbols, and a description of such constituent elements may be omitted. In FIG. 3, 21 indicates a polishing pad, and 31 indicates a transparent window plate.
In the case of the polishing pad of the present example, a polishing pad of the configuration shown in FIG. 3 may be fastened to the platen 20 of the polishing apparatus shown in FIG. 2 and used “as is”, or may be used after being fastened to the platen 20 in a form in which the polishing pad is caused to flow into the platen (comprising an aluminum plate, etc.). Alternatively, a polishing pad backed by one or more layers of other appropriate different materials may be fastened to the platen 20 and used.
[0117]FIG. 4 is a diagram which is used to illustrate a second example of a polishing pad (polishing body) of the present invention. FIG. 4(a) is a plan view, FIG. 4(b) is a sectional view of the portion indicated by line A-O in FIG. 4(a), FIG. 4(c) is a sectional view of the portion indicated by line B-O in FIG. 4(a), and FIG. 4(d) is a sectional view of the portion indicated by line C-O in FIG. 4(a). In FIG. 4, 31a through 31 c indicate window plates, and 32 a through 32 c indicate opening parts.
In the present example, the polishing body 21 has three opening parts 32 a, 32b and 32 c. Furthermore, a window plate 31 a is disposed in the opening part 32 a, a window plate 31 b is disposed in the opening part 32 b, and a window part 31 c is disposed in the opening part 32 c. In FIGS. 4(b), (c) and (d), the surface on the upper side of the polishing body 21 is the top surface of the polishing body 21, and the surfaces on the upper sides of the window plates 31 a through 31 c are the surfaces of the window plates that are located on the side of the object of polishing.
The surfaces of the respective window plates 31 a through 31 c are recessed with respect to the surface of the polishing body 21, and the respective amounts of recess are different in each of the opening parts 32 a through 32 c. As a result, the amount of recess for each of the opening parts 32 a through 32 c varies in a stepwise manner. In the polishing body 21 of the present working configuration, the amounts of recess of the surfaces of the window plates 31 a through 31 c on the side of the object of polishing with respect to the surface of the polishing body 21 are set so that the amount of recess is smallest in the case of the window plate 31 a of the opening part 32 a, and largest in the case of the window plate 31 c of the opening part 32 c. The amount of recess of the window plate 31 b of the opening part 32 b is more or less intermediate between the amount of recess of the opening part 31 a and the amount of recess of the opening part 32 c.
Such a polishing body 21 is attached to the polishing apparatus shown in FIG. 2 and used. The polishing body 21 is bonded to the platen 20 by means of a two-sided tape or an adhesive agent. Furthermore, the window plates and opening parts disposed in the polishing body 21 are omitted from FIG. 2. The opening parts 22 formed in the platen 20 and the opening parts 32 a through 32 c formed in the polishing body 21 are superimposed.
Accordingly, the above-mentioned time interval can be calculated or measured beforehand, and the polished-state measuring device 23 can be actuated after this time interval has elapsed following the output of the trigger signal by the position detection sensor. As a result, it is always possible to detect the polishing endpoint or measure the film thickness at the opening part 32 a.
Each time the polishing of one silicon wafer is completed, the polishing body is dressed. A diamond grinding wheel, etc., is used for this dressing. After dressing is performed, the next silicon wafer that is to be polished is attached to the polishing head 16, and polishing is performed. Thus, the polishing and dressing processes are alternately repeated.
[0131]FIG. 5 is a diagram which is used to illustrate a third example of a polishing pad (polishing body) of the present invention. FIG. 5(a) is a plan view, and FIG. 5(b) is a sectional view of the portion indicated by line D-E in FIG. 5(a). In FIG. 5, 32 indicates an opening part, and 33 a through 33 c indicate respective parts of a window plate 31.
In the polishing apparatus of this example, it would also be possible to perform the switching of the parts of the window plate 31 by installing a control device that switches to the next part of the window plate when the amount of light received by the polished-state measuring device 23 drops below a predetermined set value, as in Example 1-2.
[0142]FIG. 6 is a diagram which is used to illustrate a fourth example of a polishing pad (polishing body) of the present invention. FIG. 6(a) is a plan view, and FIG. 6(b) is a sectional view of the portion indicated by line F-G in FIG. 6(a). In FIG. 6, 34a through 34 d are points on the surface of the window plate 31.
The polishing body 21 of the present example has a single opening part. The parallel flat-plate window plate 31 installed in this opening part is devised so that it is inclined in section, with the amount of recess from the surface of the polishing body varying in the F-G direction in FIG. 6(a). As a result, the amount of recess of the surface of the window plate 31 on the side of the object of polishing varies in a continuous manner. In a case where four places 34 a, 34 b, 34 c and 34 d are designated on the surface of the window plate 31, the amount of recess of the surface of the window on the side of the object of polishing with respect to the surface of the polishing body is smallest in the area of 34 a, second smallest in the area of 34 b, third smallest in the area of 34 c, and greatest in the area of 34 d.
In the polishing apparatus of this example, it would also be possible to perform the switching of the areas on the window plate 31 by installing a control device that switches to the next area on the window plate when the amount of light received by the polished-state measuring device 23 drops below a predetermined set value, as in Example 1-2.
[0152]FIG. 7 is a diagram which is used to illustrate a fifth example of a polishing pad (polishing body) of the present invention. FIG. 7(a) is a plan view, and FIG. 7(b) is a sectional view of the portion indicated by line H-I in FIG. 7(a). In FIG. 7, 35a through 35 d indicate sheets of a transparent material.
Thus, in a polishing apparatus which uses the polishing body of the present example, a window in which sheets of a transparent material are laminated is installed in the polishing body; accordingly, even if the surface of the window on the side of the object of polishing should be scratched by dressing so that this surface becomes optically opaque, polishing endpoint detection or film thickness measurement can be accomplished by peeling away the transparent material
constituting the uppermost layer of the laminated window. As a result, compared to conventional polishing bodies, the same polishing body can be used in polishing for a long period of time, so that the frequency of replacement of the polishing body or window can be reduced; accordingly, the cost of polishing can be reduced.
In the Examples 1-1 through 1-5, it is desirable that the material of the polishing pad (polishing body) comprises one or more materials selected from a set comprising epoxy resins, acrylic resins, ABC resins, vinyl chloride resins, polycarbonate resins, polyester resins, fluororesins and polyurethane resins.
[0165]FIG. 8 is a diagram which is used to illustrate a sixth example of a polishing pad (polishing body) of the present invention. FIG. 8(a) is a plan view, and FIG. 8(b) is a sectional view of the portion indicated by line A-B in FIG. 8(a). In FIG. 8, 36 indicates an upper transparent material sheet, and 37 indicates a lower transparent material sheet.
It is desirable that the compressive elastic modulus of the upper transparent material sheet 36, which is the transparent material sheet located on the side of the object of polishing, be approximately the same as the compressive elastic modulus of the polishing body 21. The compressive elastic modulus of a common polishing body is in the range of 2.9×107Pa to 1.47 ×109 Pa. Accordingly, it is desirable that the compressive elastic modulus e of the upper transparent material sheet 36, which is the transparent material sheet located on the side of the object of polishing, be such that 2.9×107 Pa≦e≦1.47×109 Pa. As a result, there is no scratching of the object of polishing when the window contacts the object of polishing.
Furthermore, the above-mentioned anti-reflection film can also be formed on the undersurfaces of the window plates 31 in Examples 1-1 through 1-5.
In Examples 1-1 through 1-6, the window plates 31 are directly installed in the opening parts 32 of the respective polishing bodies 21. However, it is not necessary that the windows be directly installed in the polishing body 21. For example, it would also be possible to install the windows in the platen 20 either directly or via a jig, so that at least portions of the opening parts in the polishing body 21 are closed off.
Furthermore, in Examples 1-1 through 1-6, it is desirable that the transmissivity of the window plates 31 be 22% or greater. In this way, the attenuation of the intensity of the light that is used to measure the polished state via the window plates 31 is reduced, so that there is no drop in the polishing endpoint detection precision or film thickness measurement precision.
Furthermore, in Examples 1-1 through 1-6, it is desirable that the intensity of the light that [i] is emitted from the polished-state measuring device 23, [ii] passes through the window plate 31, [iii] passes through the polishing agent 19 between the window plate 31 a nd the silicon wafer 17, [iv] is reflected by the polished surface of the silicon wafer 17, [v] again passes through the polishing agent 19 between the window plate 31 a nd the silicon wafer 17, [vi] again passes through the window plate 31, and [vii] returns to the polished-state measuring device 23, be 1% or more of the intensity of the light 24 that is emitted form the polished-state measuring device 23. In this way, there is no drop in the intensity of the light that returns to the polished-state measuring device; accordingly, there is no drop in the polishing endpoint detection precision or film thickness measurement precision caused by the polished-state measuring device.
Furthermore, in Examples 1-1 through 1-6, dressing of the polishing body is performed; however, in cases where a non-foam material is used in the polishing body, there may be cases in which dressing is unnecessary. Even in cases where such a polishing body that does not require dressing is used, the surface of the polishing body is ground away as the object of polishing is polished. Accordingly, by using Examples 1-1 through 1-6, the frequency of replacement of the windows or polishing body can be reduced, so that the cost of polishing can be reduced.
[0183]FIG. 9 is a diagram which is used to illustrate a first example of a polishing pad (polishing body) of the present invention.
In regard to the materials used, epoxy principal agents Epicote 828 and Epicote 871 (both manufactured by Yuka Shell Epoxy K. K.) and a diaminodiphenylmethane curing agent were mixed and agitated at a weight ratio of 2.6: 3.9: 1, and this mixture was caused to flow into onto an aluminum plate with a diameter of 800 mm which had a mold with hole parts as the observation window parts. The mixture was then cured by being heated for 8 hours at 150° C., thus producing a polishing pad (polishing body) 21.
Next, a spiral V-shaped groove (angle of V: 60°) with a pitch of 0.5 mm and a depth of 0.3 mm and lattice-form grooves with a pitch of 15 mm, a width of 2 mm and a depth of 0.5 mm were formed in the surface of the above-mentioned epoxy resin by cutting. FIG. 10 shows a sectional view of the V-shaped groove 37 (angle of V: 60°) in this polishing pad 21.
The thickness of the resin part of this polishing pad 21 was 2 mm, and the amount of compressive deformation was 2 μm in the case of a load of 10 kgf/cm2 (9.8×105 Pa).
Load: 460 g/cm2 (4.5 × 104 Pa)
A polishing body of the type shown in FIG. 4 was manufactured. Here, a two-layer polishing body (hereafter referred to as “IC1000/SUBA400”) in which the lower layer of the polishing body 21 comprises SUBA400 manufactured by Rodel Co., and the upper layer comprises IC1000 manufactured by Rodel Co., was used.
Window plates 31 a, 31 b and 31 c comprise a polyurethane were respectively installed so that the amount of recess of the surface of the window on the side of the object of polishing from the surface of the polishing body was 0.15 mm in the case of the opening part 32 a, 0.3 mm in the case of the opening part 32 b, and 0.45 mm in the case of the opening part 32 c.
This polishing body was used in the polishing apparatus shown in FIG. 2, and a six-inch silicon wafer on which a thermal oxidation film had been formed to a thickness of 1 μm was polished under the conditions shown below. The residual film thickness on the silicon wafer was measured in situ by means of the polished-state measuring device 23 using the window plate 31 a in the opening part 32 a.
Load applied to polishing head: 2.4 × 104 Pa
The mean polishing rate in this case was 430 nm/min. Following the completion of polishing, dressing was performed for 1 minute using a diamond grinding wheel with an abrasive grain size of#100.
The polishing process and dressing process were repeated, with a fresh six-inch silicon wafer on which a thermal oxidation film had been formed to a thickness of 1 μm being used each time. FIG. 12 is a graph which shows the reflective spectrum from the surface of the silicon wafer measured in situ at a certain instant during polishing. Among the curves shown in the graph of FIG. 12, curve(a) indicates the reflective spectrum that was obtained. In the graph shown in FIG. 12, the horizontal axis indicates wavelength, while the vertical axis indicates the intensity ratio of the measured reflective spectrum to a standard reflective spectrum obtained in a case where a silicon wafer on which an aluminum film had been formed was installed on top of the window part of the polishing body in a state in which ion exchange water was interposed instead of the polishing agent, with the reflective spectrum of the light returning to the polished-state measuring device 23 being taken as the standard reflective spectrum. In-situ measurement of the residual film thickness of the thermal oxidation film on the silicon wafer was possible by means of wavelength fitting using a simulation.
However, the window began to be scratched by dressing following the polishing of the 120th silicon wafer, and the reflective spectrum obtained after the polishing of the 150th silicon wafer was as indicated by curve(b) in FIG. 12, so that the probability of error being generated in the in-situ measurement became large.
A polishing body of the type shown in FIG. 5 was manufactured. An IC1000/SUBA400 polishing body manufactured by Rodel Co., was used as this polishing body, and an opening part 32 was formed in one place in this polishing body 21. A window plate 31 comprises a polyurethane was installed in this opening part 32. This window plate 31 was arranged so that the amount of recess of the surface of the window plate 31 on the side of the object of polishing with respect to the surface of the polishing body 21 was respectively 0.15 mm, 0.3 mm and 0.45 mm in the respective parts 33 a, 33 b and 33 c of the window plate 31.
A polishing body of the type shown in FIG. 6 was manufactured. An IC1000/SUBA400 polishing body manufactured by Rodel Co., was used as this polishing body 21, and an opening part was formed in one place in this polishing body.
A polishing body of the type shown in FIG. 13 was manufactured. An upper transparent material sheet 36 comprises a polyurethane sheet with a size of 20 mm×50 mm and a thickness of 0.6 mm was fastened by means of a UV adhesive agent to the upper surface of a lower transparent material sheet 37 (of the same size and with a thickness of 0.5 mm) on which an anti-reflection film was formed, thus forming a two-layer window. In this case, the window 31 as a whole had a size of 20 mm×50 mm and a thickness of 1.15 mm. The anti-reflection film was formed on the surface 37 a of the acrylic sheet constituting the lower transparent material sheet 37.
A 20 mm×50 mm opening part was formed in an IC1000 polishing body (21 a) manufactured by Rodel Co., and a 10 mm×40 mm opening part was formed in an SUBA400 sub-polishing body (21 b). A two-layer polishing body 21 was formed by laminating the polishing bodies so that the centers of the respective opening parts coincided. The compressive elastic modulus of the IC1000 polishing body was 7.5×107 Pa, the compressive elastic modulus of the SUBA400 sub-polishing body was 9.6×106 Pa, the compressive elastic modulus of the acrylic was 0.29×1010 Pa, and the compressive elastic modulus of the polyurethane was 7.5×107 Pa.
pressed against the polishing body): 2.4 × 104 Pa
The mean polishing rate in this case was 430 nm/min. In this case, there was no scratching of the silicon wafer or non-uniform polishing caused by the window. FIG. 14 is a graph of reflective spectra from the surface of the silicon wafer measured in situ. Among the curves shown in the graph of FIG. 14, curve(a) is the reflective spectrum of the present embodiment.
In the graph shown in FIG. 14, the horizontal axis indicates wavelength, while the vertical axis indicates the intensity ratio of the measured reflective spectrum to a standard reflective spectrum obtained in a case where a silicon wafer on which an aluminum film had been formed was installed on top of the window part of the polishing body in a state in which ion exchange water was interposed instead of the polishing agent, with the reflective spectrum of the light returning to the polished-state measuring device 23 being taken as the standard reflective
spectrum. Measurement of the polished state (i.e., the residual film thickness of the thermal oxidation film on the silicon wafer) was possible by means of wavelength fitting using a simulation. Embodiment 1-6
A polishing body was manufactured by a process of the type shown in FIG. 15.
A quartz glass substrate 41 with a size of 20 mm×50 mm and a thickness of 1 mm, on which an anti-reflection film 42 was formed, was prepared (FIG. 15(a)). A heat-resistant tape 43 was wrapped around the periphery of this quartz glass substrate 41, thus forming a vessel with a quartz glass bottom surface (FIG. 15(b)). A resin 44 formed by mixing Epicote 828 and Epicote 871 (manufactured by Yuka Shell Epoxy K. K.) at a weight ratio of 4: 6, and mixing a dissolving p,p′-methylenedianiline (as a curing agent) with this mixture in an amount equivalent to the epoxy, was poured into the vessel and cured by heating (FIG. 15(c)). Next, after the epoxy resin 48 was cut away parallel to the quartz glass by means of a bit 49, etc., (FIG. 15 (d)), the epoxy resin 48 was worked to a mirror surface by polishing, thus producing a window 45 comprises the anti-reflection film/quartz glass/epoxy resin (in that order from the bottom) (FIG. 15(e)). In this case, the thickness of the window was 1.6 mm.
In this embodiment, quartz glass was used as the lower transparent material, and an epoxy resin was used as the upper transparent material. The compressive elastic modulus of the epoxy resin was 1.47×109 Pa, and the compressive elastic modulus of the quartz glass was 7.31 ×1010 Pa.
The mean polishing rate in this case was 210 nm/min. Furthermore, there was no scratching of the silicon wafer or non-uniform polishing caused by the window. Moreover, the reflective spectrum from the surface of the silicon wafer obtained by in-situ measurement is curve(b) in FIG. 14. Measurement of the polished state (i.e., the residual film thickness of the thermal oxidation film on the silicon wafer) was possible by means of wavelength fitting using a simulation.
An IC1000 /SUBA400 polishing body manufactured by Rodel Co., was used as a polishing body; an opening part was formed in one place in this polishing body. A window comprising a polyurethane was installed in the opening part of the polishing body so that the amount of recess of the surface of the window on the side of the object of polishing from the surface of the polishing body was 10 μm or less.
An IC1000/SUBA400 polishing body manufactured by Rodel Co., was used as a polishing body; an opening part was formed in one place in this polishing body. A window comprising an acrylic resin was installed in the opening part of the polishing body so that the amount of recess of the surface of the window on the side of the object of polishing from the surface of the polishing body was 0.1 mm.
An acrylic window with a size of 20 mm×50 mm and a thickness of 2 mm on which an anti-reflection film was formed was fastened in the same manner as in Embodiment 1-6 in the opening part of a polishing body manufactured in the same manner as in Embodiment 1-6, so that the surface of the window and the surface of the polishing body were at the same height. The recess of the surface of the window with respect to the surface of the polishing body in this case was 10 μm or less.
A polyurethane window with a size of 20 mm×50 mm and a thickness of 2 mm was fastened in the same manner as in Embodiment 1-6 in the opening part of a polishing body manufactured in the same manner as in Embodiment 1-6, so that the surface of the window and the surface of the polishing body were at the same height.
A method for adjusting the gap between the outermost surface of the polishing pad 21 (i.e., the surface that contacts the object of polishing) and the surface of the window plate 31 on the side of the outermost surface of the polishing pad 21 in the above-mentioned polishing apparatus shown in FIG. 2, this method being one example of the present invention, will be described. A device which measures the polished film thickness or the polishing endpoint from the reflective spectroscopic characteristics (reflective spectrum) is used as the polished-state measuring device 23. The reflective spectrum measured by the polished-state measuring device 23 is compared with a reference spectrum obtained by simulation, etc., in the signal processing device of the polished-state measuring device 23, so that the polished film thickness or polishing endpoint is measured.
Next, a method for measuring the polished film thickness or polishing endpoint which constitutes an example of the present invention will be described with reference to FIG. 2. Here, a device which measures the polished film thickness or polishing endpoint from the reflective spectroscopic characteristics (reflective spectrum) is used as the polished-state measuring device 23.
There may be instances in which the thickness of the layer of polishing agent between the window plate 31 and object of polishing is not constant during polishing, so that an inappropriate signal is obtained in the measurement of the polished film thickness or polishing endpoint. The term “inappropriate signal” refers to (for example) an extremely weak signal that is obtained in cases where the loss caused by the polishing agent is excessive as described above, or a signal which includes a signal caused by interference of the layer of polishing agent that is present in the recessed part formed on top of the window plate 31.
[0264]FIG. 17 is a sectional view of the area in the vicinity of the opening part in the platen of a polishing apparatus constituting an example of the present invention. In FIG. 17, 51 indicates a moving device comprising an electrically operated stage, 52 indicates a window supporting stand, 53 indicates an 0-ring, 54 indicates a gap sensor, 55 indicates a computer, 56 indicates a stage controller, and 57 indicates a motor.
The basic construction of the polishing apparatus of the present example is the same as the construction in Example 1-9 (FIG. 17); however, a position sensor is further installed on the platen 20. The position sensor that is used is a sensor that outputs a signal only when a silicon wafer is positioned above the opening part 22 in the platen (or only when no silicon wafer is positioned above the opening part in the platen), and the signal from this position sensor is input into the computer 55. Furthermore, dynamic control that is synchronized with the rotation of the platen 20 is performed, thus causing the window plate 31 to be moved, so that when a silicon wafer is present in a position other than a position above the opening part 22, the amount of recess of the surface of the window plate 31 on the side of the object of polishing with respect to the surface of the polishing body 21 is increased to a value that is greater than the gap that is present between the surface of the window plate 31 and the silicon wafer when a silicon wafer is positioned above the opening part 22.
Furthermore, in these examples as well, it is desirable that a material of the type described above be used as the window material. Example 1-11
[0282]FIG. 18 shows a schematic outline of the area in the vicinity of the polishing body of the polishing apparatus of the present example. FIG. 18(a) is a sectional view of the area in the vicinity of the opening part, and FIG. 18(b) is a sectional view which shows the conditions in the vicinity of the opening part when the object of polishing has arrived at a point above the opening part. In FIG. 18, 58 indicates a window fastening tube, 59 indicates a transparent rubber window, 60 indicates a glass window, and 61 indicates an air pressure control device.
As a result of the position of the surface of the transparent rubber window 59 being controlled as described above, there is no need to perform dressing of the polishing body 21 between polishing operations; instead, in-situ dressing is possible.
A polishing apparatus with a construction such as that shown in FIG. 17 was manufactured. A window supporting stand 52 was attached to a moving device (electrically operated stage) 51 that had a stroke of 10 mm, and an acrylic window plate 31 was installed on the upper end of this window supporting stand 52.
diluted 2X with ion exchange
[0302]FIG. 19 is a graph of the reflective spectra from the surfaces of the silicon wafers that were measured in situ at a certain instant during polishing. In the graph shown in FIG. 19, the horizontal axis indicates wavelength, while the vertical axis indicates the intensity ratio of the measured reflective spectrum to a standard reflective spectrum obtained in a case where a silicon wafer on which an aluminum film had been formed was installed on top of the window part of the polishing body in a state in which ion exchange water was interposed instead of the polishing agent, with the reflective spectrum of the light returning to the polished-state measuring device 23 being taken as the standard reflective spectrum. In the polishing of all of the 150 silicon wafers, reflective spectra such as that indicated by curve(a) in FIG. 19 were obtained at a certain instant at which the same time had elapsed from the initiation of polishing; thus, favorable in-situ measurement was accomplished.
Using the same apparatus as in Embodiment 1-7 (FIG. 17), polishing was performed using the method of Example 2-4. Control was performed so that the gap between the surface of the window on the side of the object of polishing and the polished surface of the object of polishing was 0.1 mm when the window plate 31 was positioned beneath the silicon wafer, and so that the gap between the surface of the window on the side of the object of polishing and the polished surface of the object of polishing was 0.5 mm when the window plate 31 was positioned in other positions.
Polishing agent flow rate: 200 ml/min1/32
Dressing conditions: 1 minute for each
polished, using
with an abrasive
A polishing apparatus with a construction of the type shown in FIG. 18 was manufactured. A transparent rubber window 59 with a thickness of 0.2 mm was attached to the upper end of the window fastening tube 58, and a glass window 60 was attached to the lower end.
of #100
[0315]FIG. 20 is a flow chart which illustrates the semiconductor device manufacturing process of the present invention. When the semiconductor device manufacturing process is started, an appropriate working process is first selected in step S200 from steps S201 through S204 described below. The processing then proceeds to one of the steps S201 through S204 in accordance with this selection.
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International Classification B24B37/20, B24B37/013, B24B49/12, B24B49/04, B24D7/12
Cooperative Classification B24B37/013, B24B49/04, B24B37/205, B24B49/12
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ISHIKAWA, AKIRA;SENGA, TATSUYA;MIYAJI, AKIRA;AND OTHERS;REEL/FRAME:012278/0517