Film thickness measuring device, grinding device and film thickness measuring method

Abstract

The present invention provides a film thickness measuring device, a polishing device, and a film thickness measuring method, which can suppress insufficient light intensity from reflected light from wiring patterns even when the film thickness is relatively thick. The film thickness measuring device (30) is applied to a polishing device (10) for polishing a film on a substrate (200) having a film (202) comprising multiple wiring patterns, wherein the film thickness measuring device comprises: a projector (43) that projects incident light (L1) during polishing of the film by the polishing device; a condenser (44) that focuses the incident light projected from the projector to a predetermined spot size (D) and then projects it onto the film; and a receiver (45) that receives reflected light (L2) reflected from the film, wherein the predetermined spot size is smaller than the minimum width of each wiring pattern constituting the multiple wiring patterns.

Description

Technical Field

[0001] This invention relates to a film thickness measuring apparatus, a grinding apparatus, and a film thickness measuring method. Priority is claimed based on Japanese Patent Application No. 2020-085008, filed May 14, 2020. The entire disclosure of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2020-085008 is incorporated herein by reference. Background Technology

[0002] Conventionally, to planarize the inorganic insulating film formed on a substrate, chemical mechanical polishing (CMP) is performed (see, for example, Patent Documents 1-3). Such polishing apparatus includes a polishing table that holds and rotates a polishing pad, and a substrate holding member that holds the substrate and presses the film of the substrate against the polishing pad while rotating. Furthermore, in this polishing apparatus, the polishing table and the substrate holding member rotate in the presence of a slurry, thereby polishing the film.

[0003] Furthermore, conventionally known film thickness measuring devices optically measure data related to the thickness of an inorganic insulating film during the polishing process of a polishing apparatus (see, for example, Patent Documents 1-3). Specifically, such film thickness measuring devices project incident light toward the inorganic insulating film during polishing by the polishing apparatus and measure data related to the film thickness based on the intensity of the reflected light reflected from the inorganic insulating film. Moreover, the polishing apparatus performs polishing while measuring data related to the thickness of the inorganic insulating film using the film thickness measuring device, and determines that the polishing endpoint has been reached when the film thickness reaches a predetermined value, thus ending the polishing process.

[0004] Furthermore, conventionally, films formed on a substrate include those containing multiple wiring patterns (see, for example, Patent Document 4). Additionally, films containing such wiring patterns are known to be composed of organic compounds (i.e., organic insulating films). Moreover, the planarization of such organic insulating films is performed using CMP (see, for example, Patent Document 5).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-23210

[0008] Patent Document 2: Japanese Patent Application Publication No. 2001-235311

[0009] Patent Document 3: Japanese Patent Application Publication No. 10-229060

[0010] Patent Document 4: Japanese Patent Application Publication No. 2001-21317

[0011] Patent Document 5: Japanese Patent No. 6606309

[0012] The technical problem that the invention aims to solve

[0013] However, organic insulating films are generally thicker than inorganic insulating films. Therefore, when existing thickness measurement techniques used for inorganic insulating films are directly applied to organic insulating films, the amount of reflected light from the wiring pattern may be insufficient. In such cases, it may be difficult to obtain thickness-related data during polishing. Summary of the Invention

[0014] The present invention was made in view of the above circumstances, and one of its objectives is to provide a technique that can suppress insufficient light intensity from the wiring pattern even when the film thickness is relatively thick.

[0015] Technical means for solving technical problems

[0016] (Method 1)

[0017] To achieve the above objectives, one aspect of the film thickness measuring device of the present invention is applied to a polishing apparatus for polishing a film on a substrate, the substrate having the film comprising a plurality of wiring patterns, wherein the polishing apparatus includes a polishing table holding a polishing pad, the film being pressed against the polishing pad, and the film thickness measuring device comprising: a projector that projects incident light during the polishing of the film by the polishing apparatus; a condenser that focuses the incident light projected from the projector to a predetermined spot size before projecting it onto the film; and a receiver that receives reflected light reflected from the film, the predetermined spot size being smaller than a minimum width, which is the minimum value among the widths of the plurality of wiring patterns constituting the plurality of wiring patterns.

[0018] According to this method, 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. Therefore, even when the film thickness is relatively thick, insufficient light reflected from the wiring pattern can be suppressed.

[0019] (Method 2)

[0020] In method 1 described above, the film may also be an organic insulating film composed of organic compounds. According to this method, insufficient light reflected from the wiring pattern of the organic insulating film can be suppressed.

[0021] (Method 3)

[0022] In either of the above methods 1 or 2, the projector, the condenser, and the receiver may be disposed on the polishing table, and a light-transmitting component that allows the incident light and the reflected light to pass through may be disposed on a portion of the polishing pad. According to this method, the structure of the polishing apparatus employing the film thickness measuring device can be simplified. This allows for a reduction in the manufacturing cost of the polishing apparatus.

[0023] (Method 4)

[0024] In method 3 above, the film thickness measuring device may also include a cylindrical clamp that mounts a sensor head having the projector, condenser, and receiver onto the grinding table. The clamp connects the incident light and the reflected light to the grinding table through its interior. This method easily maintains a constant distance from the sensor head to the substrate. Consequently, it is easy to make the distance from the condenser to the substrate consistent with the focal length.

[0025] (Method 5)

[0026] In any of the methods 1 to 4 described above, the concentrator may also be composed of a lens. According to this method, incident light can be focused using a simple structure.

[0027] (Method 6)

[0028] In any of the methods 1 to 5 described above, the incident light may have a wavelength in the infrared region and may be a laser. According to this method, the amount of incident light projected onto the wiring pattern can be increased. Therefore, the amount of reflected light from the wiring pattern can be increased.

[0029] (Method 7)

[0030] In any of the above methods 1 to 6, the spot size of the incident light can be set as D, the spot area of ​​the incident light can be set as S, the circumferential speed of the projector or the condenser during the polishing of the film can be set as ω, the minimum area, which is the minimum value among the areas of each of the plurality of wiring patterns constituting the plurality of wiring patterns, can be set as Smin, and the exposure time of the incident light can be set as t. In this case, the exposure time t of the incident light is set to satisfy the following formula (1):

[0031] (S+D×ω×t)≤(α×Smin)···(1),

[0032] Where α is a value chosen from the range 0 < α ≤ 2, D is in μm, and S is in μm. 2 The unit of ω is μm / sec, and the unit of Smin is μm. 2The unit of t is sec.

[0033] According to this method, the time for incident light to be projected onto the portion outside the wiring pattern can be limited within an appropriate range. This effectively suppresses insufficient light quantity from reflected light from the wiring pattern.

[0034] (Method 8)

[0035] To achieve the above objective, one aspect of the film thickness measuring device of the present invention is applied to a polishing apparatus for polishing a film on a substrate, the substrate having the film comprising a plurality of wiring patterns, wherein the polishing apparatus includes a polishing table holding a polishing pad, the film being pressed against the polishing pad, the film thickness measuring device comprising: a projector that projects incident light during the polishing of the film by the polishing apparatus; a condenser that focuses the incident light projected from the projector to a predetermined spot size and then projects it onto the film; and a receiver that receives reflected light reflected from the film, wherein the spot size of the incident light is set as D, the spot area of ​​the incident light is set as S, the circumferential speed of the projector or the condenser during the polishing of the film is set as ω, the minimum value among the areas of each of the plurality of wiring patterns, i.e., the minimum area, is set as Smin, and the exposure time of the incident light is set as t, in which case the exposure time t of the incident light is set to satisfy the following formula (1):

[0036] (S+D×ω×t)≤(α×Smin)···(1),

[0037] Where α is a value chosen from the range 0 < α ≤ 2, D is in μm, and S is in μm. 2 The unit of ω is μm / sec, and the unit of Smin is μm. 2 The unit of t is sec.

[0038] According to this method, the time for incident light to be projected onto the portion outside the wiring pattern can be limited within an appropriate range. Thus, even when the film thickness is relatively thick, insufficient light reflected from the wiring pattern can be suppressed.

[0039] (Method 9)

[0040] To achieve the above objectives, a polishing apparatus of one aspect of the present invention polishes a film on a substrate, the film of which includes multiple wiring patterns, wherein the polishing apparatus includes a film thickness measuring device of any one of the above-described aspects 1 to 8.

[0041] According to this method, since the film thickness measuring device described above is provided, even when the film thickness is relatively thick, it is possible to suppress insufficient light from the wiring pattern.

[0042] (Method 10)

[0043] To achieve the above objectives, one aspect of the film thickness measurement method of the present invention is as follows: a polishing apparatus polishes a film on a substrate, the film having a plurality of wiring patterns, and during the polishing of the film by the polishing apparatus, a film thickness measuring device of any of the above-described embodiments 1 to 8 is used to measure the film thickness.

[0044] According to this method, even when the film thickness is relatively thick, insufficient light reflected from the wiring pattern can be suppressed. Attached Figure Description

[0045] Figure 1 This is a structural diagram schematically showing the main structure of the grinding apparatus of Embodiment 1.

[0046] Figure 2 yes Figure 1 A cross-sectional view near A1.

[0047] Figure 3 It means to make Figure 2 A cross-sectional view of the substrate holding component separated from the grinding table.

[0048] Figure 4 This is a top view of the substrate of Embodiment 1.

[0049] Figure 5 This is a partial cross-sectional view of the substrate of Embodiment 1.

[0050] Figure 6 This is a diagram illustrating the structure of the sensor head and the light source / spectral assembly of the film thickness measuring device in Embodiment 1.

[0051] Figure 7 This is a cross-sectional view used to illustrate the structure of the grinding apparatus and film thickness measuring apparatus of the comparative example.

[0052] Figure 8 This diagram illustrates the situation where incident light is projected onto the film in the film thickness measuring device of the comparative example.

[0053] Figure 9 This diagram illustrates the situation where incident light is projected onto the film in the film thickness measuring device of Embodiment 1.

[0054] Figure 10A , Figure 10B and Figure 10CThis is an explanatory diagram used to explain formula (1) of a modified example of embodiment 1.

[0055] Symbol Explanation

[0056] 10 Grinding device

[0057] 11 Grinding table

[0058] 13. Substrate holding component

[0059] 20 Grinding control device

[0060] 30 Film thickness measuring device

[0061] 40 Sensor Components

[0062] 41 Sensor Head

[0063] 42 Fixtures

[0064] 43 light projector

[0065] 44 Concentrator

[0066] 45. Light receiver

[0067] 46 Glass Plate

[0068] 50 Light Source / Spectrometer

[0069] 51 Light Source

[0070] 52 beam splitter

[0071] 60 Data Processing System

[0072] 61 First Data Processing Device

[0073] 62 Second Data Processing Device

[0074] 70 Grinding Pad

[0075] 71 Grinding surface

[0076] 72 Light-transmitting components

[0077] 200 substrates

[0078] 201 substrate core

[0079] 202 membrane

[0080] 203 Wiring Pattern Construction

[0081] 204 Wiring Pattern

[0082] L1 Incident light

[0083] L2 reflected light

[0084] W1 minimum width

[0085] D Spot size

[0086] S-spot area

[0087] ω circumferential velocity

[0088] Smin (minimum area)

[0089] t Exposure time Detailed Implementation

[0090] (Implementation Method 1)

[0091] Hereinafter, the film thickness measuring apparatus 30, the grinding apparatus 10, and the film thickness measuring method of Embodiment 1 of the present invention will be described with reference to the accompanying drawings. Figure 1 The following explanation will be provided. Furthermore, the accompanying drawings of this application are schematic illustrations intended to facilitate understanding of the features of this embodiment, and are not limited to the actual dimensions or proportions of the constituent elements. Additionally, in the accompanying drawings of this application, orthogonal XYZ coordinates are illustrated for reference. In this orthogonal coordinate system, the Z-direction corresponds to upward, and the -Z-direction corresponds to downward (the direction of gravity).

[0092] Figure 1 This is a structural diagram schematically showing the main structure of the grinding apparatus 10 of this embodiment. The grinding apparatus 10 of this embodiment is a grinding apparatus capable of performing chemical mechanical polishing (CMP). Specifically, Figure 1 The illustrated grinding apparatus 10 includes a grinding table 11, a rotating shaft 12, a substrate holding member 13, a slurry supply nozzle 14, a grinding control device 20, and a film thickness measuring device 30. Figure 2 yes Figure 1 A cross-sectional view near A1. Figure 3 It means to make Figure 2 A cross-sectional view of the substrate holding member 13 separated from the grinding table 11.

[0093] like Figure 1 , Figure 2 and Figure 3 As shown, the polishing table 11 is configured to hold and rotate the polishing pad 70. Specifically, the polishing table 11 in this embodiment is composed of a disc-shaped component on which the polishing pad 70 is attached. The upper surface (surface) of the polishing pad 70 corresponds to the polishing surface 71. During polishing, the film 202 of the substrate 200 (described later) is pressed onto the polishing surface 71.

[0094] The specific type of abrasive pad 70 is not particularly limited; various abrasive pads such as rigid foam abrasive pads, non-woven fabric abrasive pads, and suede abrasive pads can be used. The abrasive pad 70 is appropriately set according to the type of membrane 202.

[0095] like Figure 1 As shown, the grinding table 11 is connected to a rotating shaft 12. The rotating shaft 12 is driven to rotate by a drive mechanism (e.g., a motor). A connector 12a is provided at the end of the rotating shaft 12 opposite to the side of the grinding table 11. This connector 12a includes a rotary joint and a rotary connector. The rotation of the grinding table 11 is controlled by the grinding control device 20, described later.

[0096] like Figure 2 and Figure 3 As shown, a portion of the polishing pad 70 in this embodiment is provided with a light-transmitting member 72 through which the incident light L1 and reflected light L2, described later, can pass. In this embodiment, the light-transmitting member 72 is composed of a window member (i.e., a light-transmitting window member), which is made of a light-transmitting material, specifically a transparent material (e.g., transparent plastic, transparent glass, etc.). The position of the light-transmitting member 72 (the relative position within the polishing pad 70) is set such that, when the polishing table 11 rotates and the polishing pad 70 rotates, at least a portion of the film 202 of the substrate 200 passes through the light-transmitting member 72. The incident light L1, focused by the condenser 44 of the sensor head 41 (described later), passes through the light-transmitting member 72 and then enters the film 202. In addition, the reflected light L2 reflected from the film 202 passes through the light-transmitting member 72 and is received by the light receiver 45 of the sensor head 41.

[0097] like Figure 1 As shown, the substrate holding member 13 is disposed on the polishing surface 71 of the polishing table 11 during polishing. Figure 2 and Figure 3 As shown, a substrate 200 is mounted on the lower surface of the substrate holding member 13. The substrate holding member 13 is configured to hold the substrate 200 and press the film 202 of the substrate 200 against the polishing surface 71 of the polishing pad 70 while rotating. In addition, this substrate holding member 13 is sometimes also referred to as a "top ring", "polishing head", etc.

[0098] Reference Figure 1The slurry supply nozzle 14 is a nozzle that supplies slurry (specifically, abrasive slurry) to the grinding surface 71. The slurry may be, for example, a solution containing abrasive particles such as silicon dioxide, aluminum oxide, or cerium oxide. The specific type of slurry is not particularly limited, as long as it is appropriately set according to the type of film 202. Furthermore, the slurry may be supplied not from the upper part of the grinding surface 71, but from the lower part, or from both the upper and lower parts of the grinding surface 71. For example, when supplying slurry from the lower part, the slurry may be supplied from a flow path (not shown) extending vertically near the rotation center of the lower part of the grinding table 11 and an opening (not shown) of the grinding pad 70 (grinding surface 71) communicating with this flow path.

[0099] The grinding control device 20 is a control device that controls the operation of the grinding apparatus 10. Specifically, the grinding control device 20 of this embodiment includes a computer. This computer includes a CPU (Central Processing Unit) 20a, which serves as a processor, a storage device 20b, etc. The storage device 20b is composed of storage media such as ROM (Read Only Memory) and RAM (Random Access Memory). In the grinding control device 20, the CPU 20a, which serves as a processor, controls the rotation of the grinding table 11, the supply of slurry from the slurry supply nozzle 14, etc., based on the program stored in the storage device 20b, thereby controlling the operation of the grinding apparatus 10.

[0100] In the grinding apparatus 10 described above, the film 202 of the substrate 200 is ground into a desired flat surface by rotating the grinding table 11 and the substrate holding member 13 in the presence of slurry.

[0101] Next, the structure of the substrate 200 will be described. Figure 4 This is a top view of substrate 200. Specifically, Figure 4 The schematic illustration shows the state of the substrate 200 as seen from below. Furthermore, in Figure 4 The illustration of membrane 202, which will be described later, is omitted. Additionally, in... Figure 4 The diagram also shows... Figure 4 An enlarged view of section A2. Figure 5 This is a partial cross-sectional view of substrate 200. Specifically, Figure 5 The diagram schematically illustrates a cross-section of a portion of substrate 200 cut using a surface containing the normal to substrate 200.

[0102] like Figure 4As shown, the substrate 200 in this embodiment is a square substrate, as an example. However, the substrate 200 is not limited to such a square substrate, and may also be a substrate with an appearance shape other than square (e.g., circular).

[0103] like Figure 5 As shown, the substrate 200 of this embodiment has a substrate core 201 and a film 202 disposed on the surface of the substrate core 201. Wiring pattern 203 is included inside the film 202. Furthermore, the substrate 200 of this embodiment is specifically a printed circuit board.

[0104] The material of the substrate core 201 is not particularly limited, but in this embodiment, as an example, a glass-based material is used. The material of the film 202 is not particularly limited, and inorganic compounds, organic compounds, etc., can be used. In this embodiment, as an example, an organic compound is used as the material of the film 202. That is, the film 202 in this embodiment is an organic insulating film. The type of organic compound is not particularly limited, but in this embodiment, as an example, a resin is used, and as an example of the resin, polyimide is used.

[0105] like Figure 4 As shown, a plurality of wiring pattern structures 203 are disposed on the surface of the substrate core 201. For example... Figure 5 As shown, the film 202 is configured to cover the surface of the plurality of wiring pattern structures 203. Each wiring pattern structure 203 has a plurality of wiring patterns 204. The material of the wiring patterns 204 is only required to be conductive, and there is no particular limitation on the specific type, but in this embodiment, copper is used as an example.

[0106] exist Figure 4 Enlarged view of section A2 and Figure 5 In this example, three wiring patterns 204 selected from a plurality of wiring patterns 204 are extracted and illustrated. These three wiring patterns 204 have widths W1, W2, and W3, respectively. Furthermore, each wiring pattern 204 has its X-direction as the short side direction and its Y-direction as the long side direction. Among the widths of the three wiring patterns 204, width W1 is the smallest value. In this embodiment, width W1 is the smallest value among all the wiring patterns 204 included in the film 202 of the substrate 200.

[0107] That is, in this embodiment, the width W1 corresponds to the minimum value among the widths of each wiring pattern 204 constituting the plurality of wiring patterns 204, i.e., the "minimum width". In addition, the "width of the wiring pattern" refers to the length of the wiring pattern in the planar direction (the direction in the XY plane) and is the length of the shorter side.

[0108] Before polishing (before CMP is performed), the wiring pattern 204 is embedded inside the film 202. The polishing apparatus 10 of this embodiment planarizes the film 202 by polishing the film 202 of the substrate 200. During the polishing of the film 202, the polishing apparatus 10 sets the moment when the film thickness of the substrate 200 reaches a predetermined value as the polishing endpoint (i.e., the "polishing endpoint"). The specific value of this polishing endpoint is not particularly limited; for example, the polishing endpoint can be set as a value below the film thickness where the wiring pattern 204 is exposed on the surface of the film 202, or it can be set as a value larger than the film thickness where the wiring pattern 204 is exposed on the surface of the film 202 (i.e., a value where the wiring pattern 204 is not exposed on the surface of the film 202).

[0109] Next, the film thickness measuring device 30 will be described. (Refer to...) Figure 1 The film thickness measuring device 30 of this embodiment is an optical film thickness measuring device that optically measures data related to the film thickness of the film 202 on the substrate 200. Furthermore, the film thickness measuring device 30 of this embodiment measures film thickness-related data during the polishing process performed by the polishing apparatus 10.

[0110] Specifically, such as Figure 1 As shown, the film thickness measuring apparatus 30 of this embodiment includes a sensor assembly 40, a light source / spectral splitter assembly 50, and a data processing system 60. The light source / spectral splitter assembly 50 and the data processing system 60 are electrically connected to the polishing control device 20 via wiring 15. In this embodiment, the sensor assembly 40 and the light source / spectral splitter assembly 50 are disposed on the polishing table 11. The sensor assembly 40 and the light source / spectral splitter assembly 50 rotate together with the polishing table 11 when the polishing table 11 rotates.

[0111] like Figure 2 and Figure 3 As shown, the sensor assembly 40 includes a sensor head 41 and a cylindrical clamp 42.

[0112] The clamp 42 is used to mount the sensor head 41 onto the grinding table 11. The clamp 42 connects to the grinding table 11 such that the incident light L1 and reflected light L2 pass through its interior. Specifically, as an example, in this embodiment, the clamp 42 is embedded in a cylindrical hole provided in the grinding table 11. Furthermore, the upper end face of the clamp 42 in this embodiment is connected to the lower surface of the glass plate 46 disposed on the lower surface of the light-transmitting member 72. The incident light L1 and reflected light L2 pass through the interior of the clamp 42 (the interior of the cylinder).

[0113] Specifically, in this embodiment, the glass plate 46 is composed of a plate component made of light-transmitting glass, and the glass plate 46 is connected to the lower surface of the light-transmitting component 72. The upper end face of the clamp 42 (the upper end face of the opening of the cylindrical clamp 42) is connected to the lower surface of the glass plate 46. The glass plate 46 effectively prevents foreign matter, such as slurry, from entering the interior of the clamp 42 (the interior of the cylinder). Furthermore, it is preferable that the clamp 42 and the lower surface of the glass plate 46 are in close contact so that no gap is formed between the clamp 42 and the glass plate 46.

[0114] In addition, the above Figure 2 and Figure 3 This is one example of the mounting method of the fixture 42 toward the grinding table 11; the mounting method of the fixture 42 toward the grinding table 11 is not limited to this. Figure 2 and Figure 3 the way exemplified.

[0115] Figure 6 This diagram illustrates the structure of the sensor head 41 and the light source / splitter assembly 50 of the film thickness measuring device 30. The sensor head 41 includes a projector 43, a condenser 44, and a receiver 45. The light source / splitter assembly 50 includes a light source 51 and a splitter 52.

[0116] The projector 43, condenser 44, and receiver 45 are housed inside the sensor head 41. The projector 43 is a device that projects incident light L1 in a predetermined direction during the grinding of the membrane 202 by the grinding apparatus 10. Specifically, in this embodiment, the projector 43 projects incident light L1 in the direction of the membrane 202. Furthermore, the projector 43 is made of optical fiber. One end of this optical fiber (the end opposite to the membrane 202 side) is connected to the light source 51. Light emitted from the light source 51 is projected as incident light L1 through this optical fiber. In this embodiment, the projector 43 and condenser 44 are independent, but this structure is not limited to. The projector 43 and condenser 44 can also be integrated.

[0117] The type of light source 51 is not particularly limited, and halogen lamps, laser light-emitting devices, etc., can be used. In this embodiment, a laser light-emitting device is used as an example of the light source 51. In addition, in this embodiment, the light emitted by the light source 51 has a wavelength in the infrared region (specifically, a wavelength longer than 780 nm). That is, the incident light L1 in this embodiment is a laser with a wavelength in the infrared region.

[0118] The concentrator 44 is a device that projects the incident light L1 projected from the projector 43 into the film 202 after achieving a predetermined spot size D (μm). This predetermined spot size D is a value smaller than the smallest value among the widths of the individual wiring patterns 204 constituting the plurality of wiring patterns 204, i.e., the "minimum width (in this embodiment, W1 (μm))". Furthermore, in this embodiment, the spot size D refers to the outer diameter of the concentrated spot of the incident light L1. As an example, the spot size D in this embodiment is set to a value of 30 μm or less (in which case, the minimum width W1 is larger than 30 μm).

[0119] As long as it has the above-mentioned functions, the specific structure of the condenser 44 is not particularly limited. As an example, the condenser 44 in this embodiment is composed of a lens (i.e., a condensing lens).

[0120] Specifically, the condenser 44 in this embodiment is composed of a lens. The lens, which serves as the condenser 44, is disposed between the projector 43 and the membrane 202, so that the incident light L1 projected from the projector 43 is focused into a predetermined spot size D and then projected onto the membrane 202.

[0121] More specifically, the focal length of the lens is set such that the focal point of the incident light L1 focused by the lens is located on the surface of the film 202 (i.e., the polishing surface 71 of the polishing pad 70). Furthermore, according to this embodiment, the distance from the lens to the film 202 of the substrate 200 is adjusted using the aforementioned clamp 42. Specifically, the distance from the lens to the film 202 is adjusted using the clamp 42 so that the focal point of the incident light L1 focused by the lens is located on the surface of the film 202. Moreover, the lens is set such that the spot size (D; i.e., the minimum spot diameter) of the incident light L1 focused by the lens is smaller than the minimum width W1 of the wiring pattern 204. Furthermore, in Figure 6 The following Figure 9 The glass plate 46 and the light-transmitting component 72 are omitted from the illustration, but in reality, the incident light L1, which is focused by the lens, passes through the glass plate 46 and the light-transmitting component 72 and then enters the film 202.

[0122] Furthermore, in this embodiment, the condenser 44 is composed of a single lens, but is not limited to this structure. The condenser 44 may also be composed of a combination of multiple lenses. Alternatively, the condenser 44 may be composed of components other than a lens. If we were to list an example of a structure other than a lens for the condenser 44, we would cite a parabolic mirror. This parabolic mirror focuses the incident light L1 projected from the projector 43 into a predetermined spot size D before projecting it onto the film 202.

[0123] The light receiver 45 is a device that receives the reflected light L2 reflected from the membrane 202. Specifically, in this embodiment, the light receiver 45 is made of an optical fiber. One end of the optical fiber (the end opposite to the membrane 202 side) is connected to the beam splitter 52.

[0124] Spectrometer 52 is a device that splits the reflected light L2 and converts the intensity of the split wavelength into a digital signal. The structure of spectrometer 52 itself is the same as that of spectrometers used in known film thickness measuring devices disclosed in prior art literature, therefore a detailed description of spectrometer 52 is omitted.

[0125] The digital signal converted by the splitter 52 is transmitted to the data processing system 60 via wiring 15. Figure 1 The data processing system 60 is a system for determining data related to the film thickness of the film 202 based on the intensity of the reflected light L2 received by the photodetector 45. Specifically, the intensity of the reflected light L2 received by the photodetector 45 is related to the film thickness. Therefore, the data processing system 60 determines data related to the film thickness of the film 202 based on the intensity of the reflected light L2 received by the photodetector 45. Furthermore, in this embodiment, the "data related to film thickness" can be any data related to the film thickness (μm), such as the film thickness itself, or an indicator related to the film thickness (e.g., the amount of change in film thickness).

[0126] Specifically, such as Figure 1 As shown, the data processing system 60 of this embodiment includes a first data processing device 61 and a second data processing device 62.

[0127] The first data processing device 61 includes a computer, which has a CPU 61a as a processor, a storage device 61b, etc. The storage device 61b is composed of storage media such as ROM and RAM. The first data processing device 61 performs data processing by causing the CPU 61a to operate based on the program stored in the storage device 61b, thereby performing data processing that indexes the reflection intensity based on the data sent from the beam splitter 52.

[0128] Data processed by the first data processing unit 61 is sent to the second data processing unit 62. The second data processing unit 62 includes a computer with a CPU 62a as a processor, a storage device 62b, etc. The storage device 62b is composed of storage media such as ROM and RAM. The second data processing unit 62 operates the CPU 62a based on a program stored in the storage device 62b, thereby performing noise removal processing on the time waveform of the exponentially sized data, and analyzing the waveform after the noise removal processing to detect reflection intensity, feature points (maximum / minimum values ​​of differential values, threshold values, etc.). This detected value (detected value) is correlated with the film thickness. Therefore, the second data processing unit 62 calculates and obtains data related to the film thickness based on this detected value. As described above, the data processing system 60 of this embodiment measures data related to the film thickness.

[0129] Furthermore, the second data processing device 62 of this embodiment determines that the film thickness has reached a preset grinding endpoint (i.e., the grinding endpoint is measured) based on the data measured as described above. When the second data processing device 62 determines that the film thickness has reached the grinding endpoint, it sends a signal indicating that the grinding endpoint has been reached (grinding endpoint signal) to the grinding control device 20. Upon receiving the grinding endpoint signal, the grinding control device 20 terminates the grinding process performed by the grinding device 10 by stopping the drive mechanism (e.g., a motor) of the grinding device 10.

[0130] Furthermore, the data processing algorithm performed by the aforementioned data processing system 60 (i.e., the data processing algorithm for determining film thickness-related data based on the intensity of reflected light) is the same as the data processing device used in the known film thickness measuring apparatus disclosed in Patent Documents 1 and 2, and these technologies can be applied. Therefore, a more detailed description of this data processing is omitted.

[0131] Here, during the polishing process, the substrate 200 moves relative to the light projector 43. Therefore, if the exposure time of the incident light L1 based on the film thickness measuring device 30 is too long, the incident light L1 will spend too much time projecting onto the portion outside the wiring pattern 204. As a result, it may be difficult to receive the reflected light L2 from the wiring pattern 204. Therefore, it is preferable to set the exposure time of the incident light L1 based on the film thickness measuring device 30 to a predetermined time or less. As the predetermined exposure time, for example, any time when it is considered difficult to receive the reflected light L2 if the exposure time is longer than this time can be used. The specific value can be appropriately set by conducting experiments, simulations, etc. in advance.

[0132] In this embodiment, as an example of the exposure time, a time of 0.1 (msec: millisecond) or less is used (i.e., a time selected from a range greater than 0.0 (msec) and less than 0.1 (msec)). This time is merely an example and is not limited thereto.

[0133] Furthermore, the film thickness measurement method of this embodiment is a method for measuring the film thickness of film 202 using the film thickness measurement device 30 described above, and is implemented by the film thickness measurement device 30 described above. That is, the film thickness measurement method of this embodiment includes the following steps: during the polishing process of the polishing apparatus 10, the projector 43 projects incident light L1; the condenser 44 focuses the incident light L1 to a predetermined spot size D and then projects it onto film 202; and the receiver 45 receives the reflected light L2 reflected from film 202. Moreover, the predetermined spot size D is set to be smaller than the minimum value, i.e., the minimum width W1, among the widths of each of the plurality of wiring patterns 204 constituting the plurality of wiring patterns 204.

[0134] Next, the effects of this embodiment will be explained while comparing it with a comparative example. Figure 7 This is a cross-sectional view used to explain the structure of the comparative example grinding apparatus 100 and film thickness measuring device 300. The comparative example grinding apparatus 100 differs from the grinding apparatus 10 of this embodiment mainly in that it does not have a light-transmitting component 72, does not have a flow path component 110, and has a film thickness measuring device 300 instead of the film thickness measuring device 30.

[0135] A flow path 111 is formed in the flow path component 110. A light-transmitting liquid FL, such as water, flows through this flow path 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 comparative example film thickness measuring device 300 differs from the film thickness measuring device 30 of this embodiment mainly in that it does not have a condenser 44, and in that it has a light emitter 43 and a light receiver 45 arranged inside the flow path component 110.

[0136] According to the comparative example film thickness measuring device 300, incident light L1 is projected from the projector 43 toward the film 202, and the receiver 45 receives the reflected light L2 reflected from the film 202. Moreover, the data processing system of the comparative example film thickness measuring device 300 obtains film thickness-related data based on the intensity of the reflected light L2 received by the receiver 45.

[0137] Figure 8 This diagram illustrates the situation where incident light L1 is projected onto film 202 in the comparative example film thickness measuring apparatus 300. (See diagram below.) Figure 8As shown, in the comparative example of the film thickness measuring apparatus 300, a concentrator 44 is not provided, so the incident light L1 projected from the projector 43 is projected onto the film 202 without focusing. In this case, the incident light L1 is projected not only onto the wiring pattern 204 in the film 202, but also onto portions of the film 202 other than the wiring pattern 204. Therefore, in the comparative example, the amount of light in the incident light L1 projected toward the film 202 that is projected onto the wiring pattern 204 is not sufficient. In such a comparative example, the amount of reflected light L2 from the wiring pattern 204 may be insufficient.

[0138] In particular, when an organic insulating film (organic insulating film) is used as film 202, compared with the case where an inorganic insulating film (inorganic insulating film) is used, film 202 is generally thicker. Furthermore, film 202 also generally has lower light transmittance. Therefore, in the case of the comparative example film thickness measuring device 300, when an organic insulating film is used as film 202, the amount of reflected light L2 from the wiring pattern 204 is particularly likely to be insufficient. Moreover, when the amount of reflected light L2 from the wiring pattern 204 is insufficient, it may be difficult to measure data related to film thickness.

[0139] Figure 9 This diagram illustrates the projection of incident light L1 onto the film 202 in the film thickness measuring apparatus 30 of this embodiment. Compared to the comparative example described above, according to this 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, thus increasing the amount of incident light L1 projected onto the wiring pattern 204. As a result, the amount of reflected light L2 from the wiring pattern 204 can be increased. Therefore, according to this embodiment, even when the film thickness of the film 202 is relatively thick, insufficient reflected light L2 can be suppressed.

[0140] Thus, according to this embodiment, even when the film thickness of film 202, such as an organic insulating film, is relatively thick, insufficient light intensity of reflected light L2 can be suppressed, and data related to film thickness can be measured during the polishing process of the polishing apparatus 10.

[0141] Therefore, according to this embodiment, even when the film thickness of the film 202 is relatively thick (such as an organic insulating film) (and when the light transmittance of the film 202 is low), the grinding endpoint can be measured during grinding, and the grinding of the film 202 can be reliably performed.

[0142] Furthermore, according to this embodiment, like Figure 2 and Figure 3As explained, the structure is as follows: a light-transmitting member 72 is disposed on the polishing pad 70, through which incident light L1 is projected onto the film 202, and reflected light L2 is received by the light receiver 45 through the light-transmitting member 72. Therefore, the film thickness can be measured without having the flow path member 110 as in the comparative example. Thus, compared with the case where the flow path member 110 is present, the structure of the polishing apparatus 10 can be simplified. As a result, the manufacturing cost of the polishing apparatus 10 can be reduced.

[0143] Furthermore, according to this embodiment, like Figure 2 and Figure 3 As explained, the device includes a cylindrical clamp 42 for mounting the sensor head 41 onto the grinding table 11, thus easily maintaining a constant distance from the sensor head 41 to the substrate 200. This allows the distance from the condenser 44 to the substrate 200 to be easily aligned with the focal length.

[0144] Furthermore, according to this embodiment, a lens is used as the concentrator 44, so the incident light L1 can be concentrated with a simple structure.

[0145] Furthermore, according to this embodiment, the incident light L1 has a wavelength in the infrared region and is laser light. Therefore, compared to the case where the incident light L1 is white light, 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 the wiring pattern 204 can be increased. Thus, data related to film thickness can be effectively measured during polishing.

[0146] (A variation of Implementation Method 1)

[0147] In Embodiment 1 described above, a constant is used as the exposure time for the incident light L1, but this structure is not limited to this. It is believed that an appropriate value for the exposure time can be taken from parameters such as the spot size of the incident light L1, the spot area of ​​the incident light L1, the circumferential speed of the projector 43 or condenser 44 during the polishing of the film 202, and the area of ​​the wiring pattern. Therefore, in this modified example, the exposure time is set based on these parameters. Specifically, as described below.

[0148] That is, let the spot size of the incident light L1 be D (μm) and the spot area of ​​the incident light L1 be S (μm). 2 The circumferential speed of the projector 43 or condenser 44 during the polishing of the membrane 202 is set to ω (μm / sec), and the minimum value of the area of ​​each wiring pattern 204 constituting the multiple wiring patterns 204, i.e., the "minimum area", is set to Smin (μm). 2When the exposure time of incident light L1 is set to t (sec), the exposure time (t) of incident light L1 in this modified example is set to satisfy the following formula (1).

[0149] (S+D×ω×t)≤(α×Smin)···(1)

[0150] (In the above formula (1), α (coefficient) is a value selected from the range of 0 < α ≤ 2)

[0151] In addition, refer to Figure 4 For example, if the lengths of the long sides of all wiring patterns 204 are the same, the minimum area Smin is equivalent to the area of ​​the wiring pattern 204 with the minimum width. However, if the lengths of the long sides of all wiring patterns 204 are different, the minimum area Smin may not be equivalent to the area of ​​the wiring pattern 204 with the minimum width.

[0152] The above formula (1) is derived based on the following viewpoint. Figures 10A to 10C This is an explanatory diagram used to illustrate formula (1) in this modified example. First, as... Figure 10A As shown, assume the light spot size D (μm) and light spot area S (μm) are... 2 The case is that an incident light L1 moves in a straight line at a speed of V (μm / sec) over a period of time ts (sec). In this case, the area of ​​the trajectory of the incident light L1 is represented by "S + D × V × ts".

[0153] like Figure 10B As shown, during the polishing process, the spot area S of the incident light L1 moves relative to the substrate 200 in an arc shape. Here, the area of ​​the trajectory of the incident light L1 during polishing is defined as the incident light trajectory area Sp (μm). 2 The incident light trajectory area Sp corresponds to the region where the film thickness can be actually measured during the grinding process (i.e., the "measured film thickness region").

[0154] Figure 10C It is obtained by extracting the area Sp of the incident light trajectory, excluding the arc-shaped portions at both circumferential ends. Here, the spot size D is smaller than the width of the wiring pattern 204, thus enabling... Figure 10C The area shown in the diagram is considered a rectangle. The result is... Figure 10C The area of ​​the region shown in the diagram can be considered as equal to... Figure 10A The areas of the "D×V×ts" shown are approximately the same.

[0155] Therefore, Figure 10C The area shown is considered to be the same as Figure 10AThe areas of the "D×V×ts" diagrams shown are the same, and the "V" is replaced with "ω (circumferential velocity)". Thus, Figure 10C The area shown is represented by "D×ω×ts". Furthermore, in this formula, time ts corresponds to the exposure time t of the incident light L1 during the film thickness measurement; therefore, this time ts is set as the exposure time t.

[0156] Thus, it can be known Figure 10B The incident light trajectory area Sp, i.e., the measured area of ​​the film thickness, is represented by "S+D×ω×t". That is, the incident light trajectory area Sp (the measured area of ​​the film thickness) is represented by adding the incident light L1 spot area S to the product of the incident light L1 spot size D and the circumferential velocity ω of the projector 43 or the condenser 44 and the exposure time t of the incident light L1. Furthermore, it is assumed that the "circumferential velocity of the projector 43" and the "circumferential velocity of the condenser 44" are the same value. Therefore, the circumferential velocity ω in formula (1) can be either the circumferential velocity of the projector 43 or the circumferential velocity of the condenser 44.

[0157] Formula (1) above specifies that the incident light trajectory area Sp calculated in this way is a value less than or equal to α times the minimum area Smin of the wiring pattern 204 (α is a value selected from the range of 0 < α ≤ 2). Based on the above viewpoint, formula (1) is derived.

[0158] Furthermore, the value of α used in formula (1) is a coefficient set to a value near 1. Considering the errors of various parameters used in formula (1), the value of α can be appropriately set to a value selected from the range of 0 < α ≤ 2, that is, a value 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. Moreover, the upper limit 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.

[0159] In the above formula (1), S, D, ω, Smin, and α are obtained in advance before the exposure time is set. Furthermore, t that satisfies formula (1) is calculated based on formula (1), and this t is set as the exposure time. The exposure time of this modified example is set as described above.

[0160] According to the modified example described above, the exposure time is set based on formula (1), thus minimizing the time it takes for the incident light L1 to be projected onto the portion outside the wiring pattern 204. Therefore, even when the film thickness of the film 202 is relatively thick, insufficient light intensity of the reflected light L2 from the wiring pattern 204 can be effectively suppressed.

[0161] (Implementation Method 2)

[0162] Next, the film thickness measuring device 30, the polishing device 10, and the film thickness measuring method according to Embodiment 2 of the present invention will be described. Furthermore, components identical to those in Embodiment 1 will be labeled with the same reference numerals, and descriptions will be omitted. Regarding the film thickness measuring device 30 and the polishing device 10 equipped with it in this embodiment, they differ from the film thickness measuring device 30 in the modified embodiment 1 described above in that it does not include a structure where "the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204". Other structures are the same as in the modified embodiment 1.

[0163] That is, the film thickness measuring device 30 of this embodiment is a film thickness measuring device 30 in Embodiment 1, which replaces the structure that "the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204" and includes a structure that "sets the exposure time of the incident light L1 to satisfy the above formula (1)". In addition, the film thickness measuring method of this embodiment is a method of measuring the film thickness of the film 202 using the film thickness measuring device 30 of this embodiment during the polishing of the film 202 by the polishing apparatus 10 of this embodiment.

[0164] According to this embodiment, similar to the variation of Embodiment 1 described above, the time it takes for the incident light L1 to be projected onto the portion outside the wiring pattern 204 can be minimized. Therefore, even when the film thickness of the film 202 is relatively thick, insufficient light intensity of the reflected light L2 from the wiring pattern 204 can be suppressed.

[0165] Furthermore, when comparing the modified example of Embodiment 1 with this embodiment, in the case where the modified example of Embodiment 1 also includes a structure in which "the spot size D of the incident light L1 is smaller than the minimum width W1 of the wiring pattern 204", it is possible to further suppress the insufficient amount of reflected light L2 from the wiring pattern 204.

[0166] The embodiments of the present invention have been described in detail above, but the present invention is not limited to this specific embodiment. Various modifications and alterations can be made within the scope of the spirit of the present invention to be protected.

Claims

1. A film thickness measuring device, used in a grinding apparatus for grinding a film on a substrate, wherein the film on the substrate comprises a plurality of wiring patterns, characterized in that, The grinding apparatus includes a grinding table that holds a grinding pad, against which the membrane is pressed. The film thickness measuring device includes: A light projector that projects incident light during the grinding process of the membrane by the grinding apparatus; A concentrator that focuses the incident light projected from the projector into a predetermined spot size before projecting it onto the membrane; as well as A light receiver that receives reflected light from the film. Let the spot size of the incident light be D, the spot area of ​​the incident light be S, the circumferential speed of the projector or the condenser during the polishing of the film be ω, the minimum area that is the minimum value among the areas of each of the plurality of wiring patterns be Smin, and the exposure time of the incident light be t. In this 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 a is a value selected from the range of 0 < a < 2, D is in units of pm, S is in units of pm 2 , ω is in units of pm / sec, and Smin is in units of pm 2 , t is in units of sec.

2. The film thickness measuring device according to claim 1, characterized in that, The membrane may contain organic or inorganic compounds.

3. The film thickness measuring device according to claim 1, characterized in that, The projector, the condenser, and the receiver are disposed on the grinding table. A portion of the abrasive pad is provided with a light-transmitting component that allows the incident light and the reflected light to pass through.

4. The film thickness measuring device according to claim 3, characterized in that, The device includes a cylindrical clamp that mounts a sensor head, comprising the projector, the condenser, and the receiver, onto the grinding table. The cylindrical clamp connects the incident light and the reflected light to the grinding table through the interior of the cylindrical clamp.

5. The film thickness measuring device according to claim 1, characterized in that, The condenser is composed of lenses.

6. The film thickness measuring device according to claim 1, characterized in that, The incident light has a wavelength in the infrared region and is a laser.

7. A polishing apparatus for polishing a film on a substrate, wherein the film on the substrate comprises a plurality of wiring patterns, characterized in that, It has the film thickness measuring device as described in claim 1.

8. A method for measuring film thickness, characterized in that, The polishing apparatus polishes a film on a substrate, the film of which includes multiple wiring patterns, and during the polishing of the film by the polishing apparatus, the film thickness is measured using the film thickness measuring device according to claim 1.

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