阅读说明：本技术 膜厚测定装置、研磨装置以及膜厚测定方法 (Film thickness measuring apparatus, polishing apparatus, and film thickness measuring method ) 是由 佐鸟博俊 石井游 金马利文 木下将毅 于 2021-05-13 设计创作，主要内容包括：本发明提供膜厚测定装置、研磨装置以及膜厚测定方法,即使在膜的膜厚较厚的情况下,也能够抑制来自布线图案的反射光的光量不足。膜厚测定装置(30)应用于对具有包含多个布线图案的膜(202)的基板(200)的膜进行研磨的研磨装置(10),其中,该膜厚测定装置具备：投光器(43),该投光器在研磨装置对膜进行研磨期间,投射入射光(L1)；聚光器(44),该聚光器使从投光器投射的入射光聚集而成为规定的光斑尺寸(D)之后,向膜投射；以及受光器(45),该受光器接收从膜反射的反射光(L2),规定的光斑尺寸与构成多个布线图案的各个布线图案的最小宽度相比较小。(The invention provides a film thickness measuring device, a polishing device and a film thickness measuring method, which can restrain the insufficient light quantity of the reflected light from a wiring pattern even if the film thickness is thick. A film thickness measuring device (30) is applied to a polishing device (10) for polishing a film of a substrate (200) having a film (202) including a plurality of wiring patterns, and is provided with: a light projector (43) for projecting incident light (L1) while the film is being polished by the polishing device; a condenser (44) that condenses the incident light projected from the projector to a predetermined spot size (D) and projects the condensed light onto the film; and a light receiver (45) that receives reflected light (L2) reflected from the film, the predetermined spot size being smaller than the minimum width of each of the wiring patterns constituting the plurality of wiring patterns.)

1. A film thickness measuring apparatus applied to a polishing apparatus for polishing a film of a substrate having a film including a plurality of wiring patterns,

the polishing apparatus includes a polishing table holding a polishing pad, the film being pressed against the polishing pad,

the film thickness measuring apparatus includes:

a light projector that projects incident light during polishing of the film by the polishing device;

a condenser that condenses the incident light projected from the projector to a predetermined spot size and projects the condensed light onto the film; and

a light receiver that receives the reflected light reflected from the film,

the predetermined spot size is smaller than a minimum width that is a minimum value among widths of the respective wiring patterns constituting the plurality of wiring patterns.

2. The film thickness measuring apparatus according to claim 1,

the film is an organic insulating film composed of an organic compound.

3. The film thickness measuring apparatus according to claim 1,

the light projector, the light condenser, and the light receiver are disposed on the polishing table,

a light-transmitting member that can transmit the incident light and the reflected light is disposed in a part of the polishing pad.

4. The film thickness measuring apparatus according to claim 3,

a cylindrical jig for attaching a sensor head having the light projector, the light collector, and the light receiver to the polishing table,

the jig is connected to the polishing table so that the incident light and the reflected light pass through the inside of the jig.

5. The film thickness measuring apparatus according to claim 1,

the condenser is constituted by a lens.

6. The film thickness measuring apparatus according to claim 1,

the incident light has a wavelength in the infrared region and is laser light.

7. The film thickness measuring apparatus according to claim 1,

when the spot size of the incident light is D, the spot area of the incident light is S, the peripheral speed of the projector or the condenser during polishing of the film is ω, the minimum area, which is the minimum value among the areas of the wiring patterns constituting the plurality of wiring patterns, is Smin, and the exposure time of the incident light is t, the exposure time t of the incident light is set to satisfy the following formula (1):

(S+D×ω×t)≤(α×Smin)···(1)，

wherein α is a value selected from the range of 0 < α ≦ 2, D is in units of μm, and S is in units of μm²In units of ω, μm/sec and in units of Smin, μm²And t is in sec.

8. A film thickness measuring apparatus applied to a polishing apparatus for polishing a film of a substrate having a film including a plurality of wiring patterns,

the polishing apparatus includes a polishing table holding a polishing pad, the film being pressed against the polishing pad,

the film thickness measuring apparatus includes:

a light projector that projects incident light during polishing of the film by the polishing device;

a condenser that condenses the incident light projected from the projector to a predetermined spot size and projects the condensed light onto the film; and

a light receiver that receives the reflected light reflected from the film,

when the spot size of the incident light is D, the spot area of the incident light is S, the peripheral speed of the projector or the condenser during polishing of the film is ω, the minimum area, which is the minimum value among the areas of the wiring patterns constituting the plurality of wiring patterns, is Smin, and the exposure time of the incident light is t, the exposure time t of the incident light is set to satisfy the following formula (1):

(S+D×ω×t)≤(α×Smin)···(1)，

wherein α is a value selected from the range of 0 < α ≦ 2, D is in units of μm, and S is in units of μm²In units of ω, μm/sec and in units of Smin, μm²And t is in sec.

9. A polishing apparatus for polishing a film of a substrate having the film including a plurality of wiring patterns,

the film thickness measuring apparatus according to claim 1.

10. A method for measuring a film thickness, characterized in that,

a polishing apparatus for polishing a film of a substrate having a plurality of wiring patterns, wherein the film thickness of the film is measured by using the film thickness measuring apparatus according to claim 1 during the polishing of the film by the polishing apparatus.

Technical Field

The invention relates to a film thickness measuring apparatus, a polishing apparatus and a film thickness measuring method. The present application claims priority based on japanese patent application No. 2020-085008, filed on 14/5/2020. The entire disclosures of the specification, claims, drawings and abstract, including japanese patent application No. 2020-085008, are incorporated herein by reference in their entirety.

Background

Conventionally, for planarizing an inorganic insulating film formed on a substrate, Chemical Mechanical Polishing (CMP) is performed, for example (see, for example, patent documents 1 to 3). The polishing apparatus used for such polishing includes: the polishing apparatus includes a polishing table that holds a polishing pad and rotates, and a substrate holding member that holds a substrate and rotates while pressing a film of the substrate against the polishing pad. Further, in this polishing apparatus, the polishing table and the substrate holding member are rotated in the presence of the slurry, thereby polishing the film.

In addition, conventionally, a film thickness measuring apparatus that optically measures data relating to the film thickness of an inorganic insulating film while a film is polished by a polishing apparatus is known (for example, see patent documents 1 to 3). Specifically, such a film thickness measuring apparatus projects incident light toward the inorganic insulating film during polishing by the polishing apparatus, and measures data relating to the film thickness based on the intensity of reflected light reflected from the inorganic insulating film. The polishing apparatus performs polishing while measuring data relating to the film thickness of the inorganic insulating film by the film thickness measuring apparatus, determines that the polishing end point is reached when the film thickness reaches a predetermined value, and ends polishing.

In addition, conventionally, as a film formed on a substrate, a film including a plurality of wiring patterns is known (for example, see patent document 4). As a film including such a wiring pattern, a film made of an organic compound (i.e., an organic insulating film) is known. In addition, CMP is also performed for planarization of the organic insulating film (see, for example, patent document 5).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent application No. 2010-23210

Patent document 2: japanese patent laid-open publication No. 2001-235311

Patent document 3: japanese laid-open patent publication No. 10-229060

Patent document 4: japanese patent laid-open publication No. 2001-21317

Patent document 5: japanese patent No. 6606309

Technical problem to be solved by the invention

However, the film thickness of the organic insulating film is thicker than that of the inorganic insulating film in many cases. Therefore, when the conventional film thickness measurement technique used for the inorganic insulating film is directly applied to the organic insulating film, the amount of reflected light from the wiring pattern may be insufficient. In this case, it may be difficult to acquire data relating to the film thickness during polishing.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique of: even when the film thickness is thick, the shortage of the light amount of the reflected light from the wiring pattern can be suppressed.

Means for solving the problems

(mode 1)

In order to achieve the above object, a film thickness measuring apparatus according to one aspect of the present invention is applied to a polishing apparatus for polishing a film on a substrate, the film including a plurality of wiring patterns, the polishing apparatus including a polishing table for holding a polishing pad, the film being pressed against the polishing pad, the film thickness measuring apparatus including: a light projector that projects incident light during polishing of the film by the polishing device; a condenser that condenses the incident light projected from the projector to a predetermined spot size and projects the condensed light onto the film; and a light receiver that receives reflected light reflected from the film, the predetermined spot size being smaller than a minimum width that is a minimum value of widths of the wiring patterns constituting the plurality of wiring patterns.

According to this aspect, since the spot size of the incident light is smaller than the minimum width of the wiring pattern, the amount of incident light projected onto the wiring pattern can be increased. This makes it possible to suppress the shortage of the amount of reflected light from the wiring pattern even when the film thickness is thick.

(mode 2)

In the above aspect 1, the film may be an organic insulating film made of an organic compound. According to this aspect, the shortage of the amount of reflected light from the wiring pattern of the organic insulating film can be suppressed.

(mode 3)

In the above-described aspect 1 or 2, the light projector, the light condenser, and the light receiver may be disposed on the polishing table, and a light transmitting member that allows the incident light and the reflected light to pass therethrough may be disposed on a part of the polishing pad. According to this aspect, the configuration of the polishing apparatus to which the film thickness measuring apparatus is applied can be simplified. This can reduce the manufacturing cost of the polishing apparatus.

(mode 4)

In the above aspect 3, the film thickness measuring apparatus may include a cylindrical jig that has a sensor head including the light projector, the light collector, and the light receiver attached to the polishing table, and the jig may be connected to the polishing table so that the incident light and the reflected light pass through an inside of the jig. According to this aspect, the distance from the sensor head to the substrate can be easily kept constant. This makes it easy to match the distance from the condenser to the substrate with the focal length.

(mode 5)

In any one of the above aspects 1 to 4, the condenser may be formed by a lens. According to this mode, incident light can be condensed with a simple structure.

(mode 6)

In any one of the above-described embodiments 1 to 5, the incident light may have a wavelength in the infrared region and may be laser light. According to this aspect, the amount of incident light projected onto the wiring pattern can be increased. This can increase the amount of reflected light from the wiring pattern.

(mode 7)

In any one of the above-described aspects 1 to 6, when the spot size of the incident light is D, the spot area of the incident light is S, the peripheral speed of the projector or the condenser during polishing of the film is ω, the minimum area that is the minimum value among the areas of the wiring patterns constituting the plurality of wiring patterns is Smin, and the exposure time of the incident light is t, the exposure time t of the incident light may be set so as to satisfy the following formula (1):

(S+D×ω×t)≤(α×Smin)···(1)，

wherein α is a value selected from the range of 0 < α ≦ 2, D is in units of μm, and S is in units of μm²In units of ω, μm/sec and in units of Smin, μm²And t is in sec.

According to this aspect, the time for projecting the incident light to the portion other than the wiring pattern can be limited to an appropriate range. This can effectively suppress the shortage of the amount of reflected light from the wiring pattern.

(mode 8)

In order to achieve the above object, a film thickness measuring apparatus according to one aspect of the present invention is applied to a polishing apparatus for polishing a film on a substrate, the film including a plurality of wiring patterns, the polishing apparatus including a polishing table for holding a polishing pad, the film being pressed against the polishing pad, the film thickness measuring apparatus including: a light projector that projects incident light during polishing of the film by the polishing device; a condenser that condenses the incident light projected from the projector to a predetermined spot size and projects the condensed light onto the film; and a light receiver that receives reflected light reflected from the film, and sets the spot size of the incident light to D, the spot area of the incident light to S, the peripheral speed of the light projector or the light collector during polishing of the film to ω, a minimum area that is a minimum value among areas of the wiring patterns constituting the plurality of wiring patterns to Smin, and an exposure time of the incident light to t, in which case the exposure time t of the incident light is set to satisfy the following formula (1):

(S+D×ω×t)≤(α×Smin)···(1)，

wherein α is a value selected from the range of 0 < α ≦ 2, D is in units of μm, and S is in units of μm²In units of ω, μm/sec and in units of Smin, μm²And t is in sec.

According to this aspect, the time for projecting the incident light to the portion other than the wiring pattern can be limited to an appropriate range. This makes it possible to suppress the shortage of the amount of reflected light from the wiring pattern even when the film thickness is thick.

(mode 9)

In order to achieve the above object, a polishing apparatus according to one aspect of the present invention polishes a film on a substrate having a film including a plurality of wiring patterns, and includes the film thickness measuring apparatus according to any one of aspects 1 to 8.

According to this aspect, since the film thickness measuring device described above is provided, even when the film thickness is thick, the shortage of the light amount of the reflected light from the wiring pattern can be suppressed.

(mode 10)

In order to achieve the above object, a film thickness measuring method according to one aspect of the present invention is a method in which a polishing apparatus polishes a film of a substrate having the film including a plurality of wiring patterns, and a film thickness of the film is measured using the film thickness measuring apparatus according to any one of aspects 1 to 8 while the polishing apparatus polishes the film.

According to this aspect, even when the film thickness is thick, the shortage of the light amount of the reflected light from the wiring pattern can be suppressed.

Drawings

Fig. 1 is a schematic diagram showing a main configuration of a polishing apparatus according to embodiment 1.

Fig. 2 is a sectional view of the vicinity a1 of fig. 1.

Fig. 3 is a cross-sectional view showing a state where the substrate holding member of fig. 2 is separated from the polishing table.

Fig. 4 is a plan view of the substrate according to embodiment 1.

Fig. 5 is a partial sectional view of the substrate according to embodiment 1.

Fig. 6 is a diagram for explaining the configuration of the sensor head and the light source/spectroscopic unit of the film thickness measurement apparatus according to embodiment 1.

Fig. 7 is a cross-sectional view for explaining the configurations of the polishing apparatus and the film thickness measuring apparatus of the comparative example.

Fig. 8 is a diagram showing a state where incident light is projected onto a film in the film thickness measuring apparatus of the comparative example.

Fig. 9 is a diagram showing a state where incident light is projected onto a film in the film thickness measurement device according to embodiment 1.

Fig. 10A, 10B, and 10C are explanatory diagrams for explaining the formula (1) of a modification of embodiment 1.

Description of the symbols

10 grinding device

11 grinding table

13 substrate holding member

20 grinding control device

30 film thickness measuring device

40 sensor assembly

41 sensor head

42 clamp

43 light projector

44 light collector

45 light receiver

46 glass plate

50 light source/light splitting assembly

51 light source

52 optical splitter

60 data processing system

61 first data processing device

62 second data processing device

70 grinding pad

71 abrasive surface

72 light-transmitting member

200 substrate

201 substrate core

202 film

203 wiring pattern structure

204 wiring pattern

Incident light of L1

L2 reflects light

W1 minimum width

D spot size

S light spot area

Omega peripheral speed

Minimum Smin area

t exposure time

Detailed Description

(embodiment mode 1)

The following describes the film thickness measuring apparatus 30, the polishing apparatus 10, and the film thickness measuring method according to embodiment 1 of the present invention, with reference to the drawings. The drawings in the present application are schematically illustrated to facilitate understanding of the features of the present embodiment, and the dimensional ratios of the components are not limited to the same as in the actual case. In addition, in the drawings of the present application, orthogonal coordinates of X-Y-Z are illustrated for reference. In the orthogonal coordinate, the Z direction corresponds to the upper side, and the-Z direction corresponds to the lower side (the direction in which gravity acts).

Fig. 1 is a schematic diagram showing the main configuration of a polishing apparatus 10 according to the present embodiment. The Polishing apparatus 10 of the present embodiment is a Polishing apparatus capable of Chemical Mechanical Polishing (CMP). Specifically, the polishing apparatus 10 illustrated in fig. 1 includes a polishing table 11, a rotating shaft 12, a substrate holding member 13, a slurry supply nozzle 14, a polishing control device 20, and a film thickness measuring device 30. Fig. 2 is a sectional view of the vicinity a1 of fig. 1. Fig. 3 is a cross-sectional view showing a state where the substrate holding member 13 of fig. 2 is separated from the polishing table 11.

As shown in fig. 1, 2, and 3, the polishing table 11 is a polishing table configured to hold a polishing pad 70 and to rotate. Specifically, the polishing table 11 of the present embodiment is formed of a disk-shaped member, and a polishing pad 70 is attached to the upper surface thereof. The upper surface (front surface) of the polishing pad 70 corresponds to a polishing surface 71. During polishing, a film 202 of a substrate 200 described later is pressed against the polishing surface 71.

Specific types of the polishing pad 70 are not particularly limited, and various polishing pads such as a hard foam type polishing pad, a nonwoven fabric type polishing pad, and a suede type polishing pad can be used. The polishing pad 70 is appropriately set according to the type of the film 202.

As shown in fig. 1, a polishing table 11 is connected to a rotating shaft 12. The rotary shaft 12 is driven to rotate by a drive mechanism (e.g., a motor). A joint 12a is provided at an end of the rotating shaft 12 opposite to the polishing table 11 side. The joint 12a includes a rotary joint and a rotary connector. The rotation operation of the polishing table 11 is controlled by a polishing control device 20 described later.

As shown in fig. 2 and 3, a translucent member 72 through which incident light L1 and reflected light L2 described later can pass is disposed in a part of the polishing pad 70 of the present embodiment. In the present embodiment, the translucent member 72 is constituted by a window member (i.e., a translucent window member) constituted by a translucent material, specifically, a transparent material (e.g., transparent plastic, transparent glass, or the like). The position of the transparent member 72 (the relative position of the polishing pad 70) is set such that at least a part of the film 202 of the substrate 200 passes over the transparent member 72 when the polishing table 11 rotates and the polishing pad 70 rotates. The incident light L1 collected by the condenser 44 of the sensor head 41 described later passes through the transparent member 72 and then enters the film 202. The reflected light L2 reflected from the film 202 passes through the translucent member 72 and is received by the light receiver 45 of the sensor head 41.

As shown in fig. 1, the substrate holding member 13 is disposed on the polishing surface 71 of the polishing table 11 during polishing. As shown in fig. 2 and 3, a substrate 200 is mounted on the lower surface of the substrate holding member 13. The substrate holding member 13 is configured to rotate while holding the substrate 200 and pressing the film 202 of the substrate 200 against the polishing surface 71 of the polishing pad 70. The substrate holding member 13 is also generally referred to as a "top ring" or a "polishing head" in some cases.

Referring to fig. 1, the slurry supply nozzle 14 is a nozzle for supplying slurry (specifically, polishing slurry) to the polishing surface 71. The slurry is, for example, a solution containing abrasive grains such as silica, alumina, and ceria. The specific type of the slurry is not particularly limited, and may be appropriately set according to the type of the film 202. The slurry may be supplied not from above but from below the polishing surface 71, or may be supplied from both above and below the polishing surface 71. For example, when the slurry is supplied from the lower portion, the slurry may be supplied from a flow path (not shown) extending vertically from a portion near the rotation center of the lower portion of the polishing table 11 and an opening (not shown) of the polishing pad 70 (polishing surface 71) communicating with the flow path.

The polishing control device 20 is a control device that controls the operation of the polishing apparatus 10. Specifically, the polishing control device 20 of the present embodiment includes a computer. The computer includes a CPU (Central Processing Unit) 20a as a processor, a storage device 20b, and the like. The storage device 20b is configured by a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory). In the polishing control device 20, the CPU20a as a processor controls the operation of the polishing apparatus 10 by controlling the rotation operation of the polishing table 11, the supply operation of the slurry from the slurry supply nozzle 14, and the like, based on a program stored in the storage device 20 b.

In the polishing apparatus 10 described above, the film 202 of the substrate 200 is polished to a desired flat surface by rotating the polishing table 11 and the substrate holding member 13 in the presence of the slurry.

Next, the structure of the substrate 200 will be described. Fig. 4 is a top view of the substrate 200. Specifically, fig. 4 schematically illustrates a state in which the substrate 200 is visually confirmed from the lower side. In fig. 4, the film 202 described later is not shown. In fig. 4, an enlarged view of a portion a2 of fig. 4 is also shown. Fig. 5 is a partial sectional view of the substrate 200. Specifically, fig. 5 schematically illustrates a cross section of a part of the substrate 200 cut by a plane including a normal line of the substrate 200.

As shown in fig. 4, the substrate 200 of the present embodiment is a square substrate, for example. However, the substrate 200 is not limited to such a square substrate, and may be a substrate having an external shape other than a square (for example, a circular shape).

As shown in fig. 5, the substrate 200 of the present embodiment includes a substrate core 201 and a film 202 disposed on a surface of the substrate core 201. The film 202 includes a wiring pattern structure 203 therein. The substrate 200 of the present embodiment is specifically a printed substrate.

The material of the substrate core 201 is not particularly limited, but in the present embodiment, a glass material is used as an example. The material of the film 202 is not particularly limited, and an inorganic compound, an organic compound, or the like can be used. In the present embodiment, an organic compound is used as an example of a material of the film 202. That is, the film 202 of this embodiment is an organic insulating film. The kind of the material of the organic compound is not particularly limited, but in the present embodiment, a resin is used as an example, and polyimide is used as an example of the resin.

As shown in fig. 4, a plurality of wiring pattern structures 203 are arranged on the surface of the substrate core 201. As shown in fig. 5, the film 202 is configured to cover the surfaces of the plurality of wiring pattern configurations 203. Each wiring pattern structure 203 has a plurality of wiring patterns 204. The material of the wiring pattern 204 is not particularly limited as long as it has conductivity, and a specific type thereof is copper, for example, in the present embodiment.

In an enlarged view of a2 part of fig. 4 and fig. 5, three wiring patterns 204 selected from the plurality of wiring patterns 204 are extracted and exemplified. The three wiring patterns 204 have a width W1, a width W2, and a width W3, respectively. Each wiring pattern 204 has the X direction as the short side direction and the Y direction as the long side direction. Among the widths of the three wiring patterns 204, the width W1 is the smallest value. In the present embodiment, the width W1 is the smallest value among all the wiring patterns 204 included in the film 202 of the substrate 200.

That is, in the present embodiment, the width W1 corresponds to the "minimum width" which is the minimum value among the widths of the respective wiring patterns 204 constituting the plurality of wiring patterns 204. Further, "width of the wiring pattern" refers to the length of the wiring pattern in the plane direction (direction within the X-Y plane) and is the length of the short side direction.

The wiring pattern 204 is buried inside the film 202 in a state before polishing (before execution of CMP). The polishing apparatus 10 of the present embodiment polishes the film 202 of the substrate 200 to planarize the film 202. In the polishing of the film 202, the polishing apparatus 10 sets a time point at which the film thickness of the substrate 200 reaches a predetermined value set in advance as an end point of the polishing (that is, "polishing end point"). The specific value of the polishing end point is not particularly limited, and for example, a value equal to or less than the film thickness of the wiring pattern 204 exposed on the surface of the film 202 may be used as the polishing end point, or a value larger than the film thickness of the wiring pattern 204 exposed on the surface of the film 202 (that is, a value within a range where the wiring pattern 204 is not exposed on the surface of the film 202) may be used as the polishing end point.

Next, the film thickness measuring apparatus 30 will be explained. Referring again to fig. 1, the film thickness measuring apparatus 30 of the present embodiment is an optical film thickness measuring apparatus that optically measures data relating to the film thickness of the film 202 on the substrate 200. The film thickness measuring apparatus 30 of the present embodiment measures data relating to the film thickness during the polishing by the polishing apparatus 10.

Specifically, as shown in fig. 1, the film thickness measuring apparatus 30 of the present embodiment includes a sensor unit 40, a light source/spectrometer unit 50, and a data processing system 60. The light source/spectroscope unit 50 and the data processing system 60 are electrically connected to the polishing control device 20 via the wiring 15. In the present embodiment, the sensor unit 40 and the light source/spectroscope unit 50 are disposed on the polishing table 11. The sensor unit 40 and the light source/spectroscope unit 50 rotate together with the polishing table 11 when the polishing table 11 rotates.

As shown in fig. 2 and 3, the sensor unit 40 includes a sensor head 41 and a cylindrical jig 42.

The jig 42 is a jig for attaching the sensor head 41 to the polishing table 11. The jig 42 is connected to the polishing table 11 so that the incident light L1 and the reflected light L2 pass through the inside of the jig 42. Specifically, the jig 42 of the present embodiment is fitted into a cylindrical hole provided in the polishing table 11, as an example. The upper end surface of the jig 42 of the present embodiment is connected to the lower surface of the glass plate 46 disposed on the lower surface of the transparent member 72. The incident light L1 and the reflected light L2 pass through the inside of the jig 42 (inside of the barrel).

Specifically, the glass plate 46 of the present embodiment is formed of a plate member made of glass that transmits light, and the glass plate 46 is connected to the lower surface of the transparent member 72. The upper end surface of the jig 42 (the upper end surface of the opening of the cylindrical jig 42) of the present embodiment is connected to the lower surface of the glass plate 46. The glass plate 46 effectively prevents foreign matter such as paste from entering the inside of the jig 42 (the inside of the cylinder). Further, it is preferable that the jig 42 is in close contact with the lower surface of the glass plate 46 so that a gap is not formed between the jig 42 and the glass plate 46.

Fig. 2 and 3 show an example of the manner of attaching the jig 42 to the polishing table 11, and the manner of attaching the jig 42 to the polishing table 11 is not limited to the manner shown in fig. 2 and 3.

Fig. 6 is a diagram for explaining the configurations of the sensor head 41 and the light source/spectroscopic unit 50 of the film thickness measurement apparatus 30. The sensor head 41 includes a light projector 43, a light collector 44, and a light receiver 45. The light source/spectroscope unit 50 includes a light source 51 and a spectroscope 52.

The light projector 43, the light condenser 44, and the light receiver 45 are housed inside the sensor head 41. The light projector 43 is a device that projects incident light L1 in a predetermined direction while the film 202 is polished by the polishing apparatus 10. Specifically, the light projector 43 of the present embodiment projects the incident light L1 toward the film 202. The light projector 43 is made of an optical fiber. One end (end on the opposite side to the film 202 side) of the optical fiber is connected to the light source 51. The light emitted from the light source 51 is projected as incident light L1 through the optical fiber. In the present embodiment, the light projector 43 and the light collector 44 are independent from each other, but the present invention is not limited to this configuration. The light projector 43 and the light collector 44 may be integrated.

The type of the light source 51 is not particularly limited, and a halogen lamp, a laser light emitting device, or the like can be used. In the present embodiment, a laser light emitting device is used as an example of the light source 51. In the present embodiment, the light emitted from the light source 51 has a wavelength in the infrared region (specifically, a wavelength longer than 780 nm). That is, the incident light L1 of the present embodiment is a laser light having a wavelength in the infrared region.

The condenser 44 is a device that projects the incident light L1 projected from the projector 43 onto the film 202 after the incident light has a predetermined spot size D (μm). The predetermined spot size D is smaller than a "minimum width (in the present embodiment, W1(μm))" which is the minimum value among the widths of the respective wiring patterns 204 constituting the plurality of wiring patterns 204. In the present embodiment, the spot size D is the outer diameter of the condensed spot of the incident light L1. For example, the spot size D of the present embodiment is set to a value of 30 μm or less (in this case, the minimum width W1 is larger than 30 μm).

The specific configuration of the condenser 44 is not particularly limited as long as the above-described functions are provided, and the condenser 44 of the present embodiment is formed of a lens (i.e., a condensing lens), as an example.

Specifically, the condenser 44 of the present embodiment is constituted by one lens. The lens serving as the condenser 44 is disposed between the projector 43 and the film 202, and condenses the incident light L1 projected from the projector 43 to a predetermined spot size D, and then projects the condensed light onto the film 202.

More specifically, the focal length of the lens is set so that the focal point of the incident light L1 condensed by the lens is located on the surface of the film 202 (i.e., the polishing surface 71 of the polishing pad 70). In addition, according to the present embodiment, the distance from the lens to the film 202 of the substrate 200 is adjusted by the jig 42 described above. Specifically, the distance from the lens to the film 202 is adjusted by the jig 42 so that the focal point of the incident light L1 condensed by the lens is located on the surface of the film 202. Also, the lens is set such that the spot size (D; i.e., the minimum spot diameter) of the incident light L1 condensed by the lens is smaller than the minimum width W1 of the wiring pattern 204. Note that, although the glass plate 46 and the light transmitting member 72 are not illustrated in fig. 6 and fig. 9 described later, the incident light L1 collected by the lens actually passes through the glass plate 46 and the light transmitting member 72 and then enters the film 202.

In the present embodiment, the condenser 44 is formed by one lens, but is not limited to this configuration. The condenser 44 may be formed by a combination of a plurality of lenses. Alternatively, the condenser 44 may be formed of a member other than a lens. An example of the structure other than the lens of the condenser 44 is a parabolic mirror. The parabolic mirror collects incident light L1 projected from the light projector 43 to a predetermined spot size D, and projects the light to the film 202.

The light receiver 45 is a device that receives the reflected light L2 reflected from the film 202. Specifically, the light receiver 45 of the present embodiment is constituted by an optical fiber. One end (end on the opposite side to the film 202 side) of the optical fiber is connected to the spectroscope 52.

The spectroscope 52 is a device that converts the intensity of the light having the wavelength after the light splitting into a digital signal by splitting the reflected light L2. The structure of the spectrometer 52 itself is the same as that used in a known film thickness measuring apparatus disclosed in the prior art document, and therefore, a detailed description of the spectrometer 52 is omitted.

The digital signal converted by the optical splitter 52 is transmitted to the data processing system 60 (fig. 1) via the wiring 15. The data processing system 60 is a system for measuring data relating to the film thickness of the film 202 based on the intensity of the reflected light L2 received by the light receiver 45. Specifically, the intensity of the reflected light L2 received by the light receiver 45 has a correlation with the film thickness. Therefore, the data processing system 60 measures data relating to the film thickness of the film 202 based on the intensity of the reflected light L2 received by the light receiver 45. In the present embodiment, the "data relating to film thickness" may be data having a correlation with the film thickness (μm), and may be, for example, the film thickness itself or an index having a correlation with the film thickness (for example, a change amount of the film thickness).

Specifically, as shown in fig. 1, the data processing system 60 of the present embodiment includes a first data processing device 61 and a second data processing device 62.

The first data processing device 61 includes a computer including a CPU61a as a processor, a storage device 61b, and the like. The storage device 61b is constituted by a storage medium such as a ROM or a RAM. The first data processing device 61 causes the CPU61a to operate based on the program stored in the storage device 61b, thereby executing data processing for indexing the reflection intensity based on the data transmitted from the spectroscope 52.

The data processed by the first data processing means 61 is sent to the second data processing means 62. The second data processing device 62 includes a computer having a CPU62a as a processor, a storage device 62b, and the like. The storage device 62b is constituted by a storage medium such as a ROM or a RAM. The second data processing device 62 operates the CPU62a based on the program stored in the storage device 62b, thereby executing noise removal processing of the time waveform of the indexed data, and analyzing the waveform after the noise removal processing to detect the reflection intensity and the characteristic point (characteristic points such as the maximum value/minimum value of the differential value, and the threshold value). The detected value (detection value) has a correlation with the film thickness. Therefore, the second data processing device 62 calculates and acquires data relating to the film thickness based on the detection value. As described above, the data processing system 60 according to the present embodiment measures data relating to the film thickness.

The second data processing device 62 of the present embodiment determines that the film thickness has reached the preset polishing end point (i.e., measures the polishing end point of polishing) based on the data measured as described above. When determining that the film thickness reaches the polishing end point, the second data processing device 62 transmits a signal (polishing end point signal) indicating that the film thickness reaches the polishing end point to the polishing control device 20. Upon receiving the polishing end point signal, the polishing control device 20 stops the driving mechanism (e.g., a motor) of the polishing apparatus 10, thereby ending the polishing by the polishing apparatus 10.

The algorithm of the data processing performed by the data processing system 60 (i.e., the data processing algorithm for measuring the data relating to the film thickness based on the intensity of the reflected light) is the same as that of the data processing apparatus used in the known film thickness measuring apparatus disclosed in patent document 1 and patent document 2, and these techniques can be applied. Therefore, a more detailed description of this data processing is omitted.

Here, since the substrate 200 is moved relative to the light projector 43 during polishing, if the exposure time of the incident light L1 by the film thickness measuring apparatus 30 is too long, the time for which the incident light L1 is projected to the portion other than the wiring pattern 204 is too long, and as a result, it may be difficult to receive the reflected light L2 from the wiring pattern 204. Therefore, the exposure time of the incident light L1 by the film thickness measuring device 30 is preferably set to a predetermined time or less. As the predetermined time of the exposure time, for example, a time in which it is considered that it is difficult to receive the reflected light L2 when the exposure time is longer than the predetermined time may be used, and a specific value thereof may be set as appropriate by performing an experiment, simulation, or the like in advance.

In the present embodiment, as an example of the exposure time, a time of 0.1 (msec: msec) or less (that is, a time selected from a range of 0.1(msec) or less that is greater than 0.0 (msec)) is used. The time is merely an example, and is not limited thereto.

The film thickness measuring method according to the present embodiment is a method for measuring the film thickness of the film 202 using the film thickness measuring apparatus 30, and is realized by the film thickness measuring apparatus 30. That is, the film thickness measuring method of the present embodiment includes the steps of: during the polishing by the polishing apparatus 10, the light projector 43 projects the incident light L1; the condenser 44 condenses the incident light L1 to a predetermined spot size D and projects the resultant light onto the film 202; and the light receiver 45 receives the reflected light L2 reflected from the film 202. The predetermined spot size D is set to be smaller than the minimum width W1, which is the minimum value among the widths of the wiring patterns 204 constituting the plurality of wiring patterns 204.

Next, the operational effects of the present embodiment will be described while comparing with the comparative example. Fig. 7 is a cross-sectional view for explaining the configurations of the polishing apparatus 100 and the film thickness measuring apparatus 300 of the comparative example. The polishing apparatus 100 of the comparative example is different from the polishing apparatus 10 of the present embodiment mainly in that it does not include the light transmitting member 72, does not include the flow path member 110, and includes the film thickness measuring apparatus 300 instead of the film thickness measuring apparatus 30.

The flow path member 110 has a flow path 111 formed therein. A liquid FL having light transmittance, such as water, passes through the flow channel 111. Specifically, the flow path 111 is configured such that the liquid flows from the lower side to the upper side, then flows along the surface of the film 202 of the substrate 200, and then flows from the upper side to the lower side. The film thickness measuring apparatus 300 of the comparative example is different from the film thickness measuring apparatus 30 of the present embodiment mainly in that it does not include the condenser 44 and in that the projector 43 and the light receiver 45 are disposed inside the flow path member 110.

According to the film thickness measuring apparatus 300 of the comparative example, the incident light L1 is projected from the light projector 43 toward the film 202, and the reflected light L2 reflected from the film 202 is received by the light receiver 45. The data processing system of the film thickness measuring apparatus 300 of the comparative example acquires data relating to the film thickness based on the intensity of the reflected light L2 received by the light receiver 45.

Fig. 8 is a diagram showing a state in which incident light L1 is projected onto the film 202 in the film thickness measuring apparatus 300 of the comparative example. As shown in fig. 8, in the case of the film thickness measuring apparatus 300 of the comparative example, since the condenser 44 is not provided, the incident light L1 projected from the projector 43 is projected onto the film 202 without being condensed. In this case, the incident light L1 is projected not only to the wiring pattern 204 in the film 202 but also to a portion other than the wiring pattern 204 in the film 202. Therefore, in the comparative example, the amount of light projected onto the wiring pattern 204 among the incident light L1 projected toward the film 202 cannot be said to be sufficient. In the case of such a comparative example, the amount of reflected light L2 from the wiring pattern 204 may be insufficient.

In particular, when a film made of an organic compound (organic insulating film) is used as the film 202, the film 202 is often thicker than when a film made of an inorganic compound (inorganic insulating film) is used. In addition, the light transmittance of the film 202 is also low in many cases. Therefore, in the case of the film thickness measuring apparatus 300 of the comparative example, when an organic insulating film is used as the film 202, the possibility that the amount of the reflected light L2 from the wiring pattern 204 is insufficient is particularly high. In addition, when the amount of reflected light L2 from wiring pattern 204 is insufficient, it may be difficult to measure data relating to film thickness.

Fig. 9 is a diagram showing a state in which incident light L1 is projected onto the film 202 in the film thickness measuring apparatus 30 according to the present embodiment. In contrast to the comparative example described above, according to the present embodiment, the spot size D of the incident light L1 is made smaller than the minimum width W1 of the wiring pattern 204 by the condenser 44, and therefore the amount of incident light L1 projected onto the wiring pattern 204 can be increased. As a result, the amount of reflected light L2 from wiring pattern 204 can be increased. Therefore, according to the present embodiment, even when the film 202 has a large thickness, the shortage of the amount of the reflected light L2 can be suppressed.

As described above, according to the present embodiment, even when the film 202 has a large film thickness such as an organic insulating film, the shortage of the light amount of the reflected light L2 can be suppressed, and data relating to the film thickness can be measured while the polishing apparatus 10 is performing polishing.

Thus, according to this embodiment, even when the film 202 has a large thickness (when the film 202 has a low light transmittance) as in the case of an organic insulating film, the polishing end point can be measured during polishing, and the film 202 can be reliably polished.

As described with reference to fig. 2 and 3, the present embodiment has the following configuration: since the polishing pad 70 is provided with the light transmitting member 72, the incident light L1 is projected to the film 202 through the light transmitting member 72, and the reflected light L2 is received by the light receiver 45 through the light transmitting member 72, the film thickness can be measured without providing the flow path member 110 as in the comparative example. This can simplify the structure of the polishing apparatus 10, compared with the case where the flow path member 110 is provided as in the comparative example. As a result, the manufacturing cost of the polishing apparatus 10 can be reduced.

In addition, according to the present embodiment, as described with reference to fig. 2 and 3, since the cylindrical jig 42 for attaching the sensor head 41 to the polishing table 11 is provided, the distance from the sensor head 41 to the substrate 200 can be easily kept constant. This makes it easy to match the distance from the condenser 44 to the substrate 200 with the focal length.

In addition, according to the present embodiment, since the condenser 44 is a lens, the incident light L1 can be condensed with a simple configuration.

Further, according to the present embodiment, since the incident light L1 has a wavelength in the infrared region and is laser light, the amount of incident light L1 projected onto the wiring pattern 204 can be increased as compared with the case where the incident light L1 is white light, for example. As a result, the amount of reflected light L2 from wiring pattern 204 can be increased. Thus, data relating to the film thickness can be effectively measured during polishing.

(modification of embodiment 1)

In embodiment 1 described above, a constant is used as the exposure time of the incident light L1, but the present invention is not limited to this configuration. It is considered that the appropriate value of the exposure time can be set to different values depending on parameters such as the spot size of the incident light L1, the spot area of the incident light L1, the peripheral speed of the projector 43 or the condenser 44 during polishing of the film 202, and the area of the wiring pattern. Therefore, in the present modification, the exposure time is set based on these parameters. Specifically, the following is described.

That is, the spot size of the incident light L1 is D (μm), and the spot area of the incident light L1 is S (μm)²) The circumferential speed of the light projector 43 or the light collector 44 during polishing of the film 202 is ω (μm/sec), and the minimum area, which is the minimum value among the areas of the wiring patterns 204 constituting the plurality of wiring patterns 204, is Smin (μm/sec)²) When the exposure time of the incident light L1 is t (sec), the exposure time (t) of the incident light L1 of the present modification is set to satisfy the following expression (1).

(S+D×ω×t)≤(α×Smin)···(1)

(in the above formula (1), α (coefficient) is a value selected from the range of 0 < α ≦ 2)

Referring to fig. 4, for example, when the lengths of the respective wiring patterns 204 in the longitudinal direction are the same, the minimum area Smin corresponds to the area of the wiring pattern 204 having the minimum width. If the lengths of the respective wiring patterns 204 in the longitudinal direction are different, the minimum area Smin does not necessarily correspond to the area of the wiring pattern 204 having the minimum width.

The above formula (1) is derived from the following point of view. Fig. 10A to 10C are explanatory diagrams for explaining the formula (1) of the present modification. First, as shown in fig. 10A, it is assumed to have a spot size D (μm) and a spot area S (μm)²) The incident light L1 moves in the linear direction at a speed V (μm/sec) within a period of time ts (sec). In this case, the area of the locus of the incident light L1 is represented by "S + D × V × ts".

As shown in fig. 10B, during polishing, the spot area S of the incident light L1 moves in an arc relative to the substrate 200. Here, the area of the locus of the incident light L1 during polishing is defined as the incident light locus area Sp (μm)²). The incident light track area Sp corresponds to a region in which the film thickness can be actually measured during polishing (i.e., "measured region of film thickness").

Fig. 10C is a diagram obtained by extracting regions of the incident light locus area Sp except for circular arc-shaped portions located at both circumferential ends. Here, the spot size D is smaller than the width of the wiring pattern 204, and therefore the area illustrated in fig. 10C can be regarded as a rectangle. As a result, the area of the region shown in fig. 10C can be regarded as substantially the same as the area of "D × V × ts" shown in fig. 10A.

Therefore, the area shown in fig. 10C is regarded as the same as the area of "D × V × ts" shown in fig. 10A, and "V" is replaced with "ω (peripheral speed)". Thus, the area shown in fig. 10C is represented by "D × ω × ts". In this equation, the time ts corresponds to the exposure time t of the incident light L1 when the film thickness is measured, and therefore the time ts is defined as the exposure time t.

Thus, the incident light track area Sp shown in fig. 10B, that is, the actually measured region of the film thickness is represented by "S + D × ω × t". That is, the incident light locus area Sp (actually measured area of film thickness) is represented by a value obtained by adding the spot area S of the incident light L1 to the product of the spot size D of the incident light L1, the peripheral speed ω of the projector 43 or the condenser 44, and the exposure time t of the incident light L1. Since "the circumferential speed of the projector 43" and "the circumferential speed of the condenser 44" are assumed to be the same value, the circumferential speed of the projector 43 or the circumferential speed of the condenser 44 may be used as the circumferential speed ω in the equation (1).

The above equation (1) specifies that the incident light track area Sp thus calculated is a value equal to or less than α times (α is a value selected from a range of 0 < α ≦ 2) of the minimum area Smin of the wiring pattern 204. From the above viewpoint, equation (1) is derived.

The value of α used in this formula (1) is a coefficient set to a value near 1. The value of α may be set as appropriate by taking into consideration errors and the like of various parameters used in the formula (1), that is, by setting values selected from the range of 0 < α ≦ 2, that is, values selected from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0. The upper limit value of α is more preferably 1.5 or less. That is, α is more preferably a value selected from the range of 0 < α ≦ 1.5.

In the above formula (1), S, D, ω, Smin, and α are obtained in advance at a stage before the exposure time is set. Then, t satisfying the formula (1) is obtained based on the formula (1), and the t is set as the exposure time. As described above, the exposure time of the present modification is set.

According to the present modification described above, since the exposure time is set based on the formula (1), the time during which the incident light L1 is projected to a portion other than the wiring pattern 204 can be reduced as much as possible. This can effectively suppress the shortage of the amount of reflected light L2 from the wiring pattern 204 even when the film 202 has a large thickness.

(embodiment mode 2)

Next, the film thickness measuring apparatus 30, the polishing apparatus 10, and the film thickness measuring method according to embodiment 2 of the present invention will be described. Note that the same components as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted. The film thickness measuring apparatus 30 of the present embodiment and the polishing apparatus 10 including the film thickness measuring apparatus 30 are different from each other in that the film thickness measuring apparatus 30 of the modification example of embodiment 1 does not include a configuration in which "the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204". The other configuration is the same as the modification of embodiment 1.

That is, the film thickness measuring apparatus 30 according to the present embodiment includes the film thickness measuring apparatus 30 having the configuration "the exposure time of the incident light L1 satisfies the above-described formula (1)" in place of the configuration "the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204" in the film thickness measuring apparatus 30 according to embodiment 1. The film thickness measuring method according to the present embodiment is a method for measuring the film thickness of the film 202 using the film thickness measuring apparatus 30 according to the present embodiment while the film 202 is polished by the polishing apparatus 10 according to the present embodiment.

According to the present embodiment, as in the modification example of embodiment 1 described above, the time required for projecting the incident light L1 to a portion other than the wiring pattern 204 can be reduced as much as possible. This can suppress the shortage of the light amount of the reflected light L2 from the wiring pattern 204 even when the film 202 has a large thickness.

In addition, when comparing the modification of embodiment 1 with the present embodiment, the modification of embodiment 1 can further suppress the shortage of the light amount of the reflected light L2 from the wiring pattern 204 in the aspect that the modification further includes the structure in which the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present invention to be protected.