CN110617786A - Pad monitoring device, pad monitoring system comprising same and pad monitoring method - Google Patents
Pad monitoring device, pad monitoring system comprising same and pad monitoring method Download PDFInfo
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- CN110617786A CN110617786A CN201811223212.0A CN201811223212A CN110617786A CN 110617786 A CN110617786 A CN 110617786A CN 201811223212 A CN201811223212 A CN 201811223212A CN 110617786 A CN110617786 A CN 110617786A
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- pad
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- window
- polishing
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 54
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- 238000005498 polishing Methods 0.000 claims abstract description 251
- 230000003746 surface roughness Effects 0.000 claims description 66
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/12—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving optical means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/005—Control means for lapping machines or devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/11—Lapping tools
- B24B37/20—Lapping pads for working plane surfaces
- B24B37/24—Lapping pads for working plane surfaces characterised by the composition or properties of the pad materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
- B24B53/017—Devices or means for dressing, cleaning or otherwise conditioning lapping tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
- B24B57/02—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/40—Image enhancement or restoration by the use of histogram techniques
-
- G06T5/70—
Abstract
A mat monitoring apparatus, a system including the same, and a mat monitoring method are disclosed. According to the pad monitoring device for monitoring the surface state of the polishing pad of one embodiment, the surface state of the polishing pad can be monitored by the scattering pattern of the light irradiated to the surface of the polishing pad.
Description
Technical Field
The following embodiments relate to a pad monitoring device, a pad monitoring system including the same, and a pad monitoring method.
Background
The manufacture of semiconductor devices requires CMP (chemical mechanical polishing) operations including grinding and polishing (buffering) and cleaning. The semiconductor device is formed in a multilayer structure, and a transistor device having a diffusion region is formed in a substrate layer. At the substrate layer, connection metal lines are patterned and electrically connected to transistor devices forming functional devices. The patterned conductive layer is insulated from other conductive layers by an insulating material like silicon dioxide, as is well known. As more metal layers and their associated insulating layers are formed, the need to make the insulating layers flat increases. If the metal layer is not flat, it is substantially more difficult to manufacture the additional metal layer due to many variations in surface morphology. In addition, the metal line pattern is formed as an insulating material, so that the metal CMP operation removes the excess metal.
The CMP process of a semiconductor includes a process of contacting a polishing member to a surface of a substrate to polish the surface of the substrate. The polishing member is required to have a certain surface roughness for polishing the substrate, and the surface roughness of the polishing member is an important factor directly affecting the reliability of the entire CMP process. Since the polishing member wears the surface during the process of repeatedly polishing the substrate, it is necessary to periodically adjust (condition) the surface of the polishing member or replace the polishing member.
However, excessive replacement of the polishing member causes an increase in maintenance cost of equipment and a problem of delaying the overall process, and insufficient replacement of the polishing member causes a problem of a decrease in yield of the substrate. Therefore, there is a need for a device that can monitor the surface condition of the abrasive member in real time.
Disclosure of Invention
It is an object of one embodiment to provide a pad monitoring device and a system including the same that monitors a conditioning state of a polishing pad during a polishing process.
It is an object of one embodiment to provide a pad monitoring device capable of monitoring a surface state of a polishing pad in real time even without interfering with a polishing process, and a system including the same.
According to a pad monitoring device for monitoring a surface state of a polishing pad according to an embodiment, the surface state of the polishing pad can be monitored by a Scattering Pattern (Scattering Pattern) of light irradiated to the surface of the polishing pad.
In one aspect, the polishing pad includes a first portion that is light transmissive and a second portion that is non-light transmissive, and the pad monitoring device irradiates light to the first portion from a side opposite to a surface of the polishing pad so that the scattering pattern can be obtained.
In one aspect, the pad monitoring device may generate an indicator of the surface roughness of the first portion from a scattering pattern of the first portion.
In one aspect, the pad monitoring device may set a correlation coefficient with respect to surface roughness of the first portion and the second portion, and may generate an index with respect to surface roughness of the second portion by a scattering pattern with respect to the first portion.
In one aspect, the pad monitoring device compares an index regarding the surface roughness of the first portion with a set index, and may detect whether a conditioning process for the polishing pad is required.
A mat monitoring device according to one embodiment may include: a light-transmissive window pad formed on the polishing pad; an optical system that irradiates light to the window pad, thereby acquiring surface state information of the window pad; and an analyzer that analyzes a surface state of the polishing pad based on the information acquired by the optical system.
In one aspect, the optical system may include: a light source for irradiating light to the window pad from a side opposite to the surface of the polishing pad; and a detection portion that receives reflected light from a surface of the window pad.
In one aspect, the detecting unit may include a CCD (Charge Coupled Device) that acquires a scatter image (scatter pattern image) from the received reflected light.
In one aspect, the analyzer may remove noise from the scatter image by fast fourier transform (fast fourier transform) of the image.
In one aspect, the analyzer may generate an index on the surface roughness of the window pad from the scattering image, and apply a set correlation coefficient to the generated index so that an index on the surface roughness of the polishing pad may be generated.
On the other hand, with the analyzer, if the amount of light detected by the detection section decreases, it can be determined that the surface roughness (roughness) of the polishing pad increases, and if the amount of light detected by the detection section increases, it can be determined that the surface roughness of the polishing pad decreases.
On the other hand, the light irradiation angle to the window pad is adjusted, and a critical angle of total internal reflection (total internal reflection) to the window pad can be detected based on the presence or absence of the reflected light received by the detection unit.
In one aspect, the analyzer may set a database for a critical angle for generating total reflection according to a surface state of the window pad, and may detect surface state information of the window pad matching the detected critical angle based on the database.
A mat monitoring system according to one embodiment may include: grinding the platen; a polishing pad attached to an upper portion of the polishing platen and having a light-transmissive window formed therein; an optical system disposed at a lower portion of the polishing platen, and configured to irradiate light to the window to obtain surface state information of the window pad; and an analyzer that monitors a surface state of the polishing pad based on information obtained by the optical system.
In one aspect, the optical system may include: a fiber optic cable attached to an underside of the window pad and forming a moving path of light; a light source connected to one side of the optical fiber cable and generating light; and a monitoring unit connected to the other side of the optical fiber cable and receiving reflected light scattered from the surface of the window pad.
In one aspect, the optical fiber cable perpendicularly irradiates light generated from the light source to the window pad, and the optical system may further include a beam splitter (beam splitter) separating the incident light irradiated to the window pad and reflected light reflected from the window pad.
In one aspect, the detector acquires a scattering image of the reflected light, and the analyzer can set an index relating to a surface state of the polishing pad based on the scattering image.
In one aspect, the pad monitoring system further comprises: a conditioning device that conditions a surface of the polishing pad; and a control part which controls the operation of the conditioning device, and the control part can determine whether to operate the conditioning device according to the surface state of the polishing pad analyzed by the analyzer.
A pad monitoring method of monitoring a surface of a polishing pad according to one embodiment may include: providing a polishing pad having a translucent window pad formed thereon; a step of irradiating light to the surface of the window pad from the side opposite to the surface of the polishing pad; a step of receiving reflected light scattered from a surface of the window pad; and a step of collecting a scatter image according to the received reflected light.
In one aspect, the step of collecting the scatter image may comprise: a step of performing image Fourier transform on the scattering image to remove noise; and converting the noise-removed scattering image into an index of a histogram (histogram).
In one aspect, the pad monitoring method may further include the step of monitoring a surface condition of the polishing pad through the collected scattering image, and the step of monitoring the surface condition may include: a step of setting a database of scattering images corresponding to the surface roughness of the window pad; and selecting surface roughness information corresponding to the collected scatter images based on the database.
In one aspect, the step of monitoring the surface condition may further comprise: a step of setting a correlation coefficient for the surface roughness of the window pad and the polishing pad, and applying the correlation coefficient to the surface roughness of the selected window pad, thereby selecting information on the surface roughness of the polishing pad.
The pad monitoring device and the system including the same according to one embodiment can monitor the state of the polishing pad in real time by a scattered light pattern that changes according to the surface state of the polishing pad.
The pad monitoring device and the system including the same according to one embodiment can predict the surface state of the entire polishing pad through the surface of the window pad, thereby monitoring the state of the polishing pad in real time even without interfering with the process of the polishing pad.
The effects of the pad monitoring device and the system including the same according to one embodiment are not limited to the above-mentioned effects, and other effects, which are not mentioned, can be clearly understood by a person of ordinary skill based on the following description.
Drawings
The following drawings attached to the present specification illustrate a preferred embodiment of the present invention and together with the detailed description of the invention serve to further understand the technical idea of the present invention, and therefore the present invention should not be construed as being limited to only the matters described in the drawings.
Fig. 1 is a diagram illustrating a process in which laser light is scattered from a surface of a substance.
FIG. 2 is a simulated diagram of a pad monitoring system according to one embodiment.
Fig. 3 is a perspective view of a mat monitoring device according to one embodiment.
FIG. 4 is a simulated view of a pad monitoring device according to one embodiment.
FIG. 5 is a scatter image of a polishing pad acquired by an optical system according to one embodiment.
FIG. 6 is a scatter image of a polishing pad acquired by an optical system according to one embodiment.
FIG. 7 is a scatter image with noise removed by an analyzer according to one embodiment.
FIG. 8 is a diagram of analysis of a scatter image by an analyzer, according to one embodiment.
FIG. 9 shows a graph of metrics generated by an analyzer, according to one embodiment.
Fig. 10 is an actual image for a plurality of pad surfaces having different roughness.
Fig. 11 is a diagram of a scattering image of the pad surface of fig. 10 analyzed by an analyzer.
Fig. 12 to 14 are diagrams of analyzing the scattering image of the pad surface of fig. 10 by an analyzer.
Fig. 15 is a graph showing a correlation between the analysis graphs of fig. 12 to 14 and the pad surface of fig. 10.
FIG. 16 illustrates a graph of a correlation of data acquired by a pad monitoring device for a pad surface and data for an actual pad surface, according to one embodiment.
FIG. 17 is a simulated view of a pad monitoring device according to one embodiment.
Fig. 18 is an optical photograph for multiple pad surfaces.
Fig. 19 is a graph showing the actual roughness for the pad surface of fig. 18.
FIG. 20 is a scatter image of the pad surface of FIG. 18 acquired by a pad monitoring device according to one embodiment.
Fig. 21 is a graph showing a correlation between an index generated from a scattering image by a pad monitoring device and actual roughness of a polishing pad.
Fig. 22 is a graph showing a change in the amount of light received according to the pad surface state.
FIG. 23 is a simulated view of a pad monitoring device according to one embodiment.
FIG. 24 is a simulated view of a pad monitoring device according to one embodiment.
FIG. 25 is a sequence diagram of a pad monitoring method according to one embodiment.
FIG. 26 is a sequence diagram of scatter image acquisition steps according to one embodiment.
Description of the reference symbols
1: pad monitoring system
101: table board
102: polishing pad
103: window pad
Detailed Description
Hereinafter, embodiments are described in detail by way of example drawings. Reference numerals are given to constituent elements of respective drawings, and it is to be noted that the same constituent elements are denoted by the same reference numerals as much as possible even when they are shown in different drawings. In describing the embodiments, detailed descriptions of related known configurations or functions are omitted when it is determined that the detailed descriptions of the related known configurations or functions interfere with understanding of the embodiments.
In addition, terms such as first, second, A, B, (a), (b), and the like may be used to describe the components of the embodiment. The terms are used only to distinguish one component from another component, and are not used to limit the nature, order, or sequence of the components. When a certain component is described as being "connected to", "coupled to" or "joined to" another component, it is to be understood that the component may be directly connected to or joined to the other component, but other components may be "connected to", "coupled to" or "joined to" each other between the components.
The components included in one embodiment and the components including common functions are described with the same names in other embodiments. Unless otherwise stated, the description of one embodiment may be applied to other embodiments, and specific description thereof will be omitted to the extent that the description is not repeated.
Fig. 1 is a diagram illustrating a process in which laser light is scattered from a surface of a substance.
Referring to fig. 1, if light is irradiated to the surface of a substance, the light is scattered according to the surface state of the substance. In general, light has a characteristic of being reflected at a boundary surface between two substances having different characteristics. The boundary surface between two substances is understood to be the surface of one substance. For example, the two substances with different characteristics may be air and a polishing pad. Therefore, in this case, the boundary surface between the two substances can be understood as the surface of the polishing pad. When light is reflected from the surface of the substance, incident light incident to the surface of the substance and reflected light reflected at the surface of the substance have the same angle with reference to a normal line (normaline) perpendicular to the surface of the substance. When light is irradiated onto the surface of a substance, the light undergoes regular reflection (regular reflection) or diffuse reflection (scattered reflection) depending on the surface state of the substance. For example, when the surface of the substance is smooth like a mirror based on a state of the light perpendicularly incident on the surface of the substance, the reflected light is reflected in a direction perpendicular to the surface of the substance. On the contrary, when the surface of the substance has a certain roughness (roughness), light perpendicularly incident on the surface of the substance is reflected in a direction determined by the normal line of a different portion with which each particle is in contact.
Since light is particulate, it can be understood that the total amount of light reflected by the surface of a substance is constant. Therefore, it can be understood that the degree of scattering of light on the surface of the substance increases as the amount of reflected light detected at a specific portion decreases. For example, when light is perpendicularly incident on the surface of the substance, the smoother the surface of the substance is, the closer the light amount of the reflected light L2 perpendicularly reflected on the surface of the substance may be to the light amount of the incident light L1. In contrast, the rougher the surface of the substance is, the incident light L1 is scattered in multiple directions, and therefore the amount of reflected light L2 that is reflected perpendicularly at the surface of the substance may decrease. It is understood that the light quantity of the reflected light L2 detected at a specific position decreases as the degree of scattering of light on the surface of the substance increases.
In general, it can be understood that the degree of scattering of light incident on the surface of a substance increases according to the surface roughness of the substance. Therefore, the surface roughness of the substance can be predicted by detecting the scattering pattern of the reflected light L2 reflected on the surface of the substance by making the light incident on the surface of the substance.
Fig. 2 is a simulation diagram of a pad monitoring system according to an embodiment, fig. 3 is a perspective view of a pad monitoring device according to an embodiment, and fig. 4 is a simulation diagram of a pad monitoring device according to an embodiment.
Referring to fig. 2 to 4, the pad monitoring system 1 according to one embodiment detects the surface roughness of the polishing pad 102 by light, so that the surface state of the polishing pad 102 can be monitored in real time. The pad monitoring system 1 according to one embodiment may include a polishing apparatus 10, a substrate carrier 130, a conditioning apparatus 140, an optical system 110, an analyzer 116, and a control section.
The polishing apparatus 10 can polish a substrate. The polishing apparatus 10 is brought into contact with the surface to be polished of the substrate to physically polish the surface to be polished of the substrate, whereby irregularities formed on the surface of the substrate can be uniformly polished and foreign matter can be removed from the surface of the substrate.
The substrate may be a silicon wafer (silicon wafer) used for manufacturing a semiconductor device (semiconductor). However, the type of substrate is not limited thereto. For example, the substrate may include glass for a flat display device (FPD) such as an LCD (liquid crystal display), a PDP (plasma display panel), or the like. Although the substrate has a disk shape in the drawings, this is for convenience of description, and the shape of the substrate is not limited to this. For example, the substrate may be formed in a quadrangular shape.
The polishing apparatus 10 may include a Platen (Platen)101, a polishing pad 102, and a window pad 103.
The platen 101 may be coupled to a polishing pad 102. For example, the platen 101 is disposed on a floor, and a polishing pad 102 may be attached to an upper portion of the platen 101. In other words, the platen 101 may have a pattern in which the ground surface of the substrate is viewed from below. The platen 101 can rotate about an axis and polish a surface to be polished of a substrate in contact with the polishing pad 102. The platen 101 is adjusted in height up and down, and the position of the polishing pad 102 relative to the floor can be adjusted.
The polishing pad 102 can polish the substrate by contacting the surface to be polished of the substrate. The polishing pad 102 may have a larger area than the substrate. In this case, the substrate can be uniformly polished while being moved over a wide area of the polishing pad 102. The polishing pad 102 may include concave and convex portions in the form of grooves (grooves) formed on the surface thereof so as to polish the surface of the substrate. The substrate surface can be physically polished by the unevenness. The substrate is physically polished between the respective irregularities and a polishing liquid (slurry) chemically reacting with the substrate can be introduced. In order to uniformly polish the surface of the substrate, it is necessary to maintain the polishing pad 102 in a concave-convex shape with a certain roughness. In the polishing pad 102, when the substrate is polished, the polishing pad wears and the size of the unevenness gradually decreases, that is, the surface of the polishing pad 102 becomes flat. Therefore, in order to maintain the surface roughness of the polishing pad 102 during the polishing of the substrate, an operation of maintaining the shape of the irregularities is required.
The polishing pad 102 may comprise a material having a microscopic elasticity. For example, the polishing pad 102 may comprise polyurethane (polyurethane) with a hollow polymer. The hollow of the polishing pad 102 can function to absorb the elasticity applied to the polishing pad 102 so that the polishing pad 102 and the substrate are in more intimate contact. The polishing pad 102 may include a first portion that is light transmissive and a second portion that is not light transmissive depending on the degree of hollowing.
The window pad 103 may be formed on a portion of the polishing pad 102. The window pad 103 may be formed to be more hollow than other portions of the polishing pad 102 in a form capable of transmitting light. In other words, the window pad 103 may be a first portion of the polishing pad 102, and other portions of the polishing pad 102 where the window pad 103 is not formed may be a second portion. The portion of the platen 101 to which the window pad 103 is attached may be formed with a through groove 1011 extending from the bottom surface to the window pad 103. Therefore, the light irradiated from the lower side of the platen 101 can pass through the lower surface of the window pad 103 through the through groove 1011 and reach the surface of the window pad 103, that is, the polishing surface. According to the above-described configuration, in order to observe the surface state of the polishing pad 102, the light may be irradiated from the surface opposite to the surface of the polishing pad 102 without directly irradiating the surface of the polishing pad 102 with the light.
During the polishing of the substrate, the surface of the window pad 103 is continuously worn, and the surface variation of the window pad 103 and the surface variation of other portions of the polishing pad 102 may be changed toward the same trend. In other words, it can be understood that the surface state of the first and second portions of the polishing pad 102 changes toward the same trend during polishing. Therefore, it can be understood that the surface state of the polishing pad 102 and the surface state of the window pad 103 are changed identically.
The substrate carrier 130 may hold a substrate. The substrate carrier 130 may chuck and clamp the substrate and move the clamped substrate toward the upper portion of the polishing pad 102. The substrate carrier 130 may bring the substrate, which is transferred to the upper portion of the polishing pad 102, into contact with the polishing pad 102 for polishing the substrate. The substrate carrier 130 may adjust a frictional force generated between the substrate and the polishing pad 102 by pressurizing the substrate in contact with the polishing pad 102. When the polishing of the substrate is completed, the substrate carrier 130 releases the contact between the substrate and the polishing pad 102, and can transfer the substrate so that the substrate is separated from the polishing pad 102.
The conditioning device 140 may condition the surface of the polishing pad 102. The conditioning device 140 may physically polish the polishing pad while contacting the surface of the polishing pad. Contaminants remaining on the surface of the polishing pad 102 can be removed by the conditioning process and the surface of the polishing pad can be reprocessed. The conditioning device 140 may include a conditioning pad in contact with the polishing pad. The conditioning pad may include a substance capable of conditioning the hardness of the surface of the polishing pad, and may include diamond (diamond) particles, for example. Since the surface of the conditioning pad has the concave-convex portions in the form of grooves, the surface of the polishing pad 102 polished by the conditioning pad can be subjected to a regeneration treatment so as to have a roughness suitable for polishing a substrate.
The optical system 110 can acquire information about the surface state of the polishing pad 102 by light. The optical system 110 irradiates incident light to the surface of the polishing pad 102, and by detecting reflected light reflected from the surface of the polishing pad 102, information on the surface state of the polishing pad 102 can be acquired. The optical system 110 can estimate the roughness (roughness) of the surface of a local portion of the surface of the polishing pad 102 by the scattering pattern of light irradiated to the local portion.
The optical system 110 can detect the surface state of the polishing pad 102 in real time while the polishing process is being performed. For example, the optical system 110 is provided at a lower portion of the platen 101, and by irradiating light from a lower side of the window pad 103, that is, from an opposite side of a polished surface of the window pad 103, information on the surface state of the window pad 103 can be acquired. Since the window pad 103 is made of a light-transmitting material, incident light applied to the optical system 110 can be reflected on the surface of the window pad 103 through the window pad 103. Since the portion of the polishing pad 102 that is in contact with the substrate or the conditioning pad is continuously changed during the polishing process, continuous irradiation of light to the surface of the polishing pad 102 can be restricted. As described above, when the optical system 110 irradiates the window pad 103 with light from the side opposite to the surface of the polishing pad 102, the surface state of the window pad 103 can be continuously and continuously monitored. The optical system 110 may include a light source 111, a fiber optic cable 115, a lens 113, a beam splitter 112, and a detection section 114.
The light source 111 may generate light. For example, the light source 111 may be a laser device that generates laser light. For example, the light source 111 may be located on the underside of the window pad 103. In this case, light generated from the light source 111 may be vertically irradiated toward the window pad 103 through the optical fiber cable 115.
The fiber optic cable 115 may form a moving path of light used in the optical system 110. For example, the optical fiber cable 115 is attached to the lower surface of the window pad 103, and is connected to the light source 111, so that the path of incident light can be set in such a manner that light generated from the light source 111 is irradiated toward the window pad 103. The optical fiber cable 115 can set a path of the reflected light so that the reflected light reflected from the surface of the window pad 103 is directed to the detection portion 114. By using a plurality of optical fiber cables 115, a light moving path to the light source 111, the window pad 103, and the detection section 114 can be provided.
The lens 113 may condense light generated from the light source 111 toward the surface of the window pad 103. For example, the light-transmitting mirror 113 may be a convex lens 113 that concentrates light generated from the light source 111 toward the center.
The beam splitter 112(beam splitter) can separate incident light irradiated toward the window pad 103 and reflected light reflected from the window pad 103. For example, in the case where the detection unit 114 and the light source 111 are not located on the same line, the beam splitter 112 may pass incident light emitted from the light source 111 and reflect reflected light reflected from the window pad 103 toward the detection unit 114.
The detection section 114 may detect the reflected light reflected from the window surface. The incident light irradiated to the surface of the window pad 103 has different degrees of scattering according to the surface roughness of the window pad 103. The detection unit 114 may receive reflected light of the scattered light, which has the same angle as the incident light with respect to a normal line perpendicular to the surface of the polishing pad 102. For example, the detector 114 may be a CCD (charge coupled device) that acquires a scatter image (scatter pattern image) of the received reflected light.
The analyzer 116 may analyze the surface state of the polishing pad, for example, the roughness of the surface of the polishing pad, based on the information acquired by the optical system 110. The analyzer 116 may generate an indicator of surface roughness for a second portion, e.g., for a non-light transmissive portion of the window pad 103, by polishing a first portion of the pad 102, e.g., by a scattering pattern of the window pad 103. Because the roughness of the surface of the first portion and the second portion of the polishing pad 102 varies with the same trend during the polishing process, the analyzer 116 can analyze the variation of the surface roughness of the second portion through the scattering pattern of the first portion.
The analyzer 116 can monitor the surface state of the polishing pad 102 through the scattering image acquired by the detecting section 114. Thus, the surface condition of the polishing pad 102 monitored by the analyzer 116 can confirm whether the polishing pad 102 needs to be conditioned or whether the polishing pad 102 needs to be replaced. For example, the analyzer 116 generates an index for the surface roughness of the first portion based on the scattering image, and compares it with the set index, so that it is possible to detect whether the conditioning process for the polishing pad 102 is required.
The control unit can determine whether to operate the conditioning device 140 based on the surface condition of the polishing pad 102 analyzed by the analyzer 116. For example, when the surface of the polishing pad 102 has a sufficient roughness required for polishing a substrate, the control section prevents unnecessary activation of the apparatus and the conditioning process of the polishing pad 102 by stopping the operation of the conditioning apparatus 140, and when the surface of the polishing pad 102 is in a state unsuitable for polishing a substrate, the surface of the polishing pad 102 can be regenerated by operating the conditioning apparatus 140. According to the described manner, it is possible to save the maintenance cost of the polishing pad 102 and minimize the generation of defective silicon chips by preventing unnecessary conditioning processes.
The following describes in detail a process of monitoring the surface state of the polishing pad 102 by the analyzer 116.
FIG. 5 is a scatter image of the polishing pad 102 acquired by the optical system 110, according to one embodiment.
The surface of the polishing pad 102 has a certain roughness (roughness) for physical polishing of the substrate. In the polishing process, a plurality of substrates are repeatedly polished by the polishing pad 102, in which the surface of the polishing pad 102 is gradually worn away and flattened. Since the degree of scattering of light on the surface of the polishing pad 102 increases according to the surface roughness of the polishing pad 102, it can be understood that the surface of the polishing pad 102 becomes rougher as the amount of reflected light received by the detection unit 114 decreases.
Referring to fig. 5, it can be confirmed that the scattering patterns of the reflected light received from the window pad 103 are different before and after the polishing (polishing) of the substrate by the polishing pad 102. Specifically, since the surface of the window pad 103 is changed from a rough state to a smooth (smooth) state the more the polishing pad 102 is used, it can be confirmed that as the surface roughness of the window pad 103 decreases, the degree of scattering from the surface of the window pad 103 decreases, and as a result, the light amount of reflected light received by the detection section 114 increases.
FIG. 6 is a scatter image of the polishing pad 102 acquired by the optical system 110, according to one embodiment.
In an actual polishing process, a liquid similar to a polishing liquid (slurry) or deionized Water (DI Water) is sprayed onto the surface of the polishing pad 102. The liquid flows into the grooves formed in the surface of the polishing pad 102 to level the surface of the polishing pad 102. According to the optical system 110 of one embodiment, light is irradiated from the opposite side of the surface of the polishing pad 102, i.e., from the lower side of the window pad 103, so that the scattering pattern of the surface of the window pad 103 can be detected. According to the above configuration, interference of the scattering pattern on the surface of the window pad 103 can be prevented by the liquid sprayed on the surface of the polishing pad 102.
Referring to fig. 6, it can be confirmed that even in a state where the surface of the polishing pad 102 is sprayed with liquid, the scattering image acquired by the detection section 114 can be distinguished according to the surface roughness of the polishing pad 102. The left image 6a of fig. 6 is a scattering image of the window pad 103 in an initial state, and the right image 6b is a scattering image of the window pad 103 in a state where the surface is worn. Comparing the two images, it was confirmed that the degree of scattering of light from the window pad 103 in a state where the surface was worn out was small, and therefore the scattering range was small and the light amount concentration was high in the scattering image of the window pad 103.
FIG. 7 is a scatter image with noise removed by the analyzer 116 according to one embodiment.
Referring to fig. 7, the analyzer 116 according to an embodiment may remove noise of a scattering image through Fast Fourier Transform (FFT) of the image. The analyzer 116 performs an image FFT process on the scatter image acquired by the detection section 114, so that the resolution according to the change of the scatter pattern is improved, and it can be digitized so as to enable calculation. The analyzer 116, through the transformation of the scatter image, as shown in fig. 7, can grade the luminosity appearing in the scatter image and can quantify it and analyze it.
FIG. 8 is a diagram of analysis of a scatter image by analyzer 116, according to one embodiment.
Referring to fig. 8, it can be confirmed that the variation of the scattering pattern according to the surface roughness of the window pad 103 occurs with high resolution in the case of FFT conversion of the scattering image of the light irradiated to the surface of the window pad 103. The analyzer 116 quantifies the scattering image received by the detector in terms of the luminosity of each pixel, and by displaying the quantified values in terms of different pixels, the change in the scattering pattern according to the change in the surface state of the window pad 103 can be indexed. Fig. 8 shows a graph 8a of a scattering image of the window pad 103 in a dry state without polishing liquid, and a graph 8b of a scattering image of the window pad 103 in a wet state with polishing liquid sprayed. Comparing the two graphs, it can be confirmed that the scattering pattern is more clearly changed as the surface state of the polishing pad is changed in the state where the polishing liquid is sprayed, similarly to the actual state, when the scattering pattern is indexed for each pixel luminosity. According to the pad monitoring system 1 of one embodiment, since the scattering pattern change of the window pad 103 is detected by irradiating light from the lower side of the polishing pad 102, the scattering pattern change can be detected more accurately and with resolution than the case of directly irradiating light to the surface of the polishing pad 102.
Fig. 9 is a diagram of the indexing of a scatter image by the analyzer 116 according to one embodiment.
Referring to fig. 9, it can be confirmed that, in the case of histogram the number of pixels having the same luminosity in the FFT-converted scattering image, the histogram shows different profiles according to the surface roughness of the pad window.
In the graph of fig. 9, the X-axis represents the luminance of a pixel, and the Y-axis represents the number of pixels having the same luminance. Fig. 9a is the window pad 103 for the rough surface state and fig. 9b is the window pad 103 for the smooth surface state. Comparing the two graphs confirms that the histogram of the window pad 103 in the surface rough state is narrower in the luminous intensity distribution than the histogram of the window pad 103 in the surface smooth state. That is, since the histograms of the scatter images have different profiles from each other according to the surface roughness of the window pad 103, the analyzer 116 can predict the surface state change of the window pad 103 from the profiles of the respective histograms. For example, the analyzer 116 sets data of a histogram profile corresponding to the surface state of the window pad 103, and by comparing a histogram of the detected scatter image with the set data, information on the surface state of the matching window pad 103 can be acquired.
Fig. 10 is an actual image for a plurality of pad surfaces having different roughness, and fig. 11 is an analysis diagram obtained by a scattering image of the pad surface of fig. 10.
As can be confirmed by referring to fig. 10 and 11, the mat monitoring system 1 according to one embodiment effectively detects the surface state change of the window mat 103. Window pads 103 of 3 kinds having different surface states as shown in fig. 10 are prepared, and the surface states of the respective window pads 103 are photographed. As confirmed in fig. 10, it can be confirmed that the surface roughness is reduced in order of the window pads 103 of the photographs 10a, 10b, 10 c.
A scatter image of 4 fulcrums is acquired for each window pad 103, and an average pixel (pixel) number above a certain luminosity is calculated therefrom to be shown in fig. 11. As confirmed in fig. 11, it was confirmed that the average number of pixels having a light intensity of a certain value or more is different depending on the surface state of the window pad 103. Therefore, by the trend of change of the graph in which the scattering image is indexed by the analyzer 116, the change of the surface state of the window pad 103 can be predicted.
Fig. 12 to 14 are graphs of scattering images of the pad surface of fig. 10 analyzed by the analyzer 116, and fig. 15 is a graph showing a correlation between the analysis graphs of fig. 12 to 14 and the pad surface of fig. 10.
Referring to fig. 12 to 15, the analyzer 116 generates an index for the surface roughness of the window pad 103 from the scattering image, and applies the set correlation coefficient to the generated index, so that a prediction result value for the surface roughness of the polishing pad can be generated.
In the scatter image of the window pad 103 in fig. 10, a histogram is acquired in which the number of pixels having the same light amount is classified by the intensity of the light amount (intensity). Fig. 12 to 14 are graphs for converting the acquired histogram into a gaussian function (gaussian function) form. For reference, fig. 12 to 14 correspond to the window pads 103 of fig. 10a, 10b, 10c, respectively, of fig. 10. Considering the graphs of fig. 12 to 14 as the sum of two gaussian functions having mutually different peaks (peak), the respective gaussian functions are separated to obtain a center value (intensity center), a full width at half maximum (FWHM), and a height value (height) for the two peaks.
Referring to fig. 15, it can be confirmed that the respective values obtained from fig. 12 to 14 have certain tendencies according to the variation of the surface roughness of the window pad 103.
The graph 15a of fig. 15 shows the change in the central value of the peak detected from fig. 12 to 14. From the left to the right, the surface roughness (roughnesss) of the actual pad decreases in order. In this case, it is confirmed that the center value of the peak shown in the graph 15a is reduced as the surface roughness of the pad is reduced.
Graph 15b of fig. 15 shows the change in full width at half maximum of the peak detected from fig. 12 to 14. As shown in the drawing, it was confirmed that the full width at half maximum of the peak increases in sequence the more the surface roughness of the pad decreases.
In general, it is understood that there is a correlation between the actual roughness change of the pad window and the index value extracted from the scatter image of the window pad 103. Therefore, the set correlation coefficient is applied to the index value extracted from the scattering image by the analyzer 116, and thereby the prediction result value for the surface roughness of the actual polishing pad 102 can be obtained. However, the above-described tendency between the index value of the scattering image and the surface state of the actual polishing pad 102 is merely an example, and the analyzer 116 may selectively apply the correlation coefficient according to various index values.
Fig. 16 is a graph illustrating a correlation between data of a pad surface acquired by a pad monitoring device and data of an actual pad surface according to an embodiment.
Referring to fig. 16, it can be confirmed that the index value obtained by the pad monitoring device has a certain tendency and varies according to the variation of the roughness of the actual pad surface.
R of FIG. 16aIs a curve showing the variation of actual roughness of three kinds of window pads measured by a test instrument, R of FIG. 16qIs a curve representing the variation of the index value extracted by the pad monitoring device from the scatter image of the same window pad. For reference, RqThe index value is obtained by converting a scattering image into a curve in a gaussian function form and extracting a center value (intensity center) of a first peak from the converted curve.
Observe R of FIG. 16aAnd RqIt can be confirmed that the variation of the index value extracted by the pad monitoring device has a tendency similar to the variation of the roughness of the actual pad. Therefore, the pad monitoring apparatus can estimate the roughness change of the actual polishing pad by the change of the index value extracted through the scattering image.
FIG. 17 is a simulated view of a pad monitoring device according to one embodiment.
Referring to fig. 17, the pad monitoring device according to one embodiment directly irradiates light to the surface of the polishing pad from the upper portion of the polishing pad, so that the surface state of the polishing pad can be monitored. The pad monitoring device may include a light source 1711, a detection portion 1712, and an analyzer.
The light source 1711 and the detection unit 1712 may be arranged symmetrically with respect to a normal line perpendicular to the ground. The detection unit 1712 is provided so as to have a reflection angle equal to the incident angle of light from the light source 1711 to the polishing pad. The more the roughness of the surface state of the polishing pad increases, the more the degree of scattering of light from the polishing pad surface increases, so that information on the surface state of the polishing pad can be acquired by the scattering pattern of the reflected light received by the detection section 1712.
The analyzer generates an index based on the scattering pattern acquired by the detector 1712, and can generate a predicted result value for the surface roughness of the polishing pad by applying a set correlation coefficient to the generated index.
Fig. 18 is an optical photograph of a plurality of polishing pad surfaces, fig. 19 is a graph showing actual roughness of the pad surface of fig. 18, fig. 20 is a scattering image of the polishing pad surface of fig. 18 acquired by a pad monitoring device, and fig. 21 is a graph showing a correlation between an index generated by the pad monitoring device based on the scattering image and actual roughness of the polishing pad.
Referring to fig. 18 to 21, the pad monitoring apparatus may estimate the surface state of the polishing pad by a correlation between an index generated based on a scattering image acquired for the surface of the polishing pad and the actual roughness of the polishing pad.
The used polishing pads were adjusted for every minute, two minutes, and three minutes, and optical photographs of the polishing pad surface as shown in fig. 18 were taken at each adjustment time. For reference, photograph 18a is a photograph of a polishing pad subjected to conditioning for one minute, photograph 18b is a photograph of a polishing pad subjected to conditioning for two minutes, and photograph 18c is a photograph of a polishing pad subjected to conditioning for three minutes.
The measured values of the actual roughness of the polishing pad surface corresponding to the respective photographs as shown in fig. 19 were obtained. Graph 19a corresponds to photograph 18a, graph 19b corresponds to photograph 18b, and graph 19c corresponds to photograph 18 c. Numerical values for the mean square (RMS) and average (average) of the variation values appearing in the respective graphs are obtained. The values obtained are shown in table 1.
[ TABLE 1 ]
| 19a | 19b | 19c | |
| Mean square (μm) | 4.095 | 3.513 | 3.209 |
| Mean value of | 3.130 | 2.645 | 2.443 |
Scattered light images for each of the polishing pads of fig. 18 as shown in fig. 20 were acquired. Image 20a corresponds to photograph 18a, image 20b corresponds to photograph 18b, and image 20c corresponds to photograph 18 c. The scatter image of fig. 18 is subjected to image fast fourier transform, and then a median (mean) of histograms for the light quantity of each pixel is acquired. The median values obtained are shown in table 2.
[ TABLE 2 ]
| 20a | 20b | 20c | |
| Median count | 7.353 | 7.290 | 7.122 |
As a result of comparing the value according to the actual surface state of the polishing pad with the index value obtained from the scattering image of fig. 20, it was confirmed that the polishing pad had a tendency as shown in the graph of fig. 21. In the graph of fig. 21, the X-axis represents the conditioning time (min) performed on the pad. Therefore, it was confirmed that the surface roughness of the pad increased as going from the left side to the right side. It can be confirmed from the graphs 21a and 21b of fig. 21 that the variation tendency of the median, the square mean, and the average obtained from the scattering image decreases as the surface roughness of the pad increases.
Therefore, it can be understood that there is a certain correlation between the actual roughness variation of the polishing pad and the index value extracted from the scattering image. Therefore, by applying the set correlation coefficient to the index value extracted from the scattering image by the analyzer, the change in the surface roughness of the actual polishing pad can be estimated.
Fig. 22 is a graph showing a change in the amount of light received according to the pad surface state.
Referring to fig. 22, the pad monitoring device may detect a surface state change of the polishing pad by a reception degree of reflected light reflected from the surface of the pad.
In the Pad Breaking (Pad Breaking) step, a conditioning process may be performed for the use of the polishing Pad. Thus, the surface roughness (roughness) of the polishing Pad is increased in the Pad Breaking (Pad Breaking) step. Therefore, the more the surface roughness of the polishing pad increases, the more the degree of scattering of light on the surface of the polishing pad increases, and therefore the amount of light received decreases.
In the conditioning (conditioning) step, the substrate is brought into contact with the polishing pad so that the polishing process for polishing the substrate and the conditioning process are simultaneously performed. After the Pad Breaking (Pad Breaking) step is completed, only the polishing process is performed, and then the conditioning process is performed in order, so that the surface roughness of the polishing Pad is reduced and then concentrated to a certain value again. Therefore, the amount of reflected light received by the pad monitoring device is concentrated to a constant value after the initial increase.
In the No conditioning (No conditioning) step, No conditioning is performed, and only the polishing process is performed. In this case, the polishing pad surface roughness decreases with the lapse of time, so the amount of reflected light received by the pad monitoring device increases.
After that, if the conditioning (conditioning) step is performed again, it is confirmed that the surface roughness of the polishing pad increases and then converges to a constant value.
In general, the roughness of the polishing pad and the amount of reflected light reflected from the surface of the polishing pad are inversely proportional, so the pad monitoring device can monitor the degree of change in the surface state of the polishing pad by the change in the amount of light received from the surface of the polishing pad. For example, the analyzer of the pad monitoring apparatus may determine that the surface roughness (roughness) of the polishing pad increases if the amount of light detected by the detecting part decreases, and may determine that the surface roughness of the polishing pad decreases if the amount of light detected by the detecting part increases.
Fig. 23 is a simulation diagram of a pad monitoring device according to an embodiment, and fig. 24 is a simulation diagram of a pad monitoring device according to an embodiment.
Referring to fig. 23 to 24, the pad monitoring apparatus according to an embodiment may monitor a surface state of the polishing pad 102 by total internal reflection (total internal reflection) of light. By total reflection is meant 100% reflection of light from the surface of a substance. The light-transmitting substance has a certain refractive index (reactive index) depending on the type of the substance, and light cannot pass through the substance and is totally reflected depending on the refractive index. The critical angle is the smallest angle of incidence at which total reflection of light occurs. The pad monitoring device detects an incident angle at which total reflection occurs on the surface of the window pad 103 according to the roughness, so that the surface state of the window pad 103 can be monitored. The pad monitoring device may include a light source, a detection portion, and an analyzer.
The light source 2311 may irradiate light toward the surface of the window pad 103 from the lower side of the polishing pad 102. In this case, the irradiation angle of the light irradiated to the window pad 103 can be adjusted. The normal to the local portion of the window pad may vary depending on the surface curvature of the window pad. The detection portion 2315 may receive reflected light from the window pad 103. The detection portion 2315 may detect an incident angle of the light source that generates total reflection with respect to the window pad 103. In the case where the amount of light received from the window pad 103 and the amount of light irradiated are the same, it can be understood that the incident angle of the light source 2311 with respect to the surface of the window pad 103 reaches a critical angle.
The analyzer sets a database about incident angles at which total reflection occurs according to the surface state of the window pad 103, and by detecting information on the surface state of the window pad 103 matching the incident angle detected from the database, it is possible to monitor the surface state change of the polishing pad 102.
Hereinafter, a pad monitoring method according to an embodiment is explained. In explaining the pad monitoring method, duplicate description with the above description will be omitted.
Fig. 25 is a sequence diagram of a pad monitoring method according to an embodiment, and fig. 26 is a sequence diagram of a scatter image acquisition step according to an embodiment.
Referring to fig. 25 and 26, a pad monitoring method according to one embodiment may monitor a surface of a polishing pad. The pad monitoring method may include: the method includes the steps of providing a polishing pad having a window pad formed thereon 2500, irradiating light to the window pad 2510, receiving reflected light scattered from a surface of the window pad 2520, collecting a scattered image according to the received reflected light 2530, and monitoring the surface of the polishing pad 2540.
In step 2500, a polishing pad with a light transmissive window pad can be provided. The polishing pad can include a window pad portion that is light transmissive and a portion that is not light transmissive.
Light may be irradiated from the side opposite to the surface of the polishing pad toward the surface of the window pad in step 2510. For example, light may be illuminated from the platen toward the surface of the window pad in step 2510. Light that is directed toward the surface of the window pad may be reflected from the surface of the window pad through the underside of the window pad.
In step 2520, reflected light scattered from the surface of the window pad may be received. The degree of scattering of light may be different according to the surface state of the window pad.
In step 2530, a scatter image from the received reflected light may be collected. Step 2530 may include a noise removal step 2531 and a conversion to an index step 2532.
Step 2531 converts the acquired scatter image by fast fourier transform, whereby the noise of the scatter image can be removed.
In step 2532, the noise-removed scatter image may be converted into an index. The indicator may be, for example, a histogram of the intensity and count for the amount of light per pixel in the scatter image.
Step 2540 may monitor the surface condition of the polishing pad from the collected scatter images. Step 2540 may set a database of scatter images corresponding to the surface roughness of the window pad and may select surface roughness information corresponding to the collected scatter images. Step 2540 may set correlation coefficients for the surface roughness of the window pad and the polishing pad, and apply the set correlation coefficients to the surface roughness of the selected window pad, from which information about the surface roughness of the polishing pad may be selected.
In contrast, in step 2540, the set correlation coefficient is applied to the index of the scattering image acquired in step 2530, so that a result value of the predicted roughness of the polishing pad can be generated.
As described above, although the embodiments have been described with reference to the limited drawings, those having ordinary knowledge in the art can make various modifications and variations based on the description. For example, even when the described techniques are executed in a different order from the described method, or the components of the structures, devices, and the like described are combined or combined in a different form from the described method, or replaced or substituted with other components or equivalents, appropriate results can be achieved.
Claims (22)
1. A pad monitoring device for monitoring a surface state of a polishing pad by a scattering pattern of light irradiated to the surface of the polishing pad.
2. The mat monitoring device according to claim 1,
the polishing pad comprises a first light-transmitting portion and a second non-light-transmitting portion,
the pad monitoring device irradiates light to the first portion from an opposite side of the polishing pad surface to acquire the scattering pattern.
3. The mat monitoring device according to claim 2,
the pad monitoring device generates an indicator for surface roughness of the first portion from a scattering pattern of the first portion.
4. The mat monitoring device according to claim 3,
the pad monitoring device sets correlation coefficients for surface roughness of the first and second portions, and generates an indicator for surface roughness of the second portion by a scattering pattern of the first portion.
5. The mat monitoring device according to claim 3,
the pad monitoring device compares the index for the surface roughness of the first portion with the set index, thereby detecting whether a conditioning process for the polishing pad is required.
6. A mat monitoring device, comprising:
a light-transmissive window pad formed on the polishing pad;
an optical system that irradiates light to the window pad, thereby acquiring surface state information of the window pad; and
an analyzer that analyzes a surface state of the polishing pad based on the information acquired by the optical system.
7. The mat monitoring device according to claim 6,
the optical system includes:
a light source that irradiates light to the window pad from a side opposite to a surface of the polishing pad; and
a detection portion that receives reflected light from a surface of the window pad.
8. The mat monitoring device according to claim 7,
the detection section includes a CCD that acquires a scattered image from the received reflected light.
9. The mat monitoring device according to claim 8,
and the analyzer removes the noise of the scattering image through image fast Fourier transform.
10. The mat monitoring device according to claim 8,
the analyzer generates an index from the scattering image, and applies a set correlation coefficient to the generated index to generate a predicted result value for the surface roughness of the polishing pad.
11. The mat monitoring device according to claim 7,
with respect to the said analyzer, the said analyzer is provided with a plurality of sensors,
if the light quantity detected by the detection part is reduced, the surface roughness of the polishing pad is judged to be increased,
if the light quantity detected by the detection part is increased, the surface roughness of the polishing pad is judged to be reduced.
12. The mat monitoring device according to claim 7,
adjusting an angle of light irradiation with respect to the window pad,
the detection section detects an incident angle at which total reflection occurs with respect to the window pad according to the amount of received reflected light.
13. The mat monitoring device according to claim 12,
the analyzer sets a database for incident angles at which total reflection occurs according to a surface state of the window pad, and detects surface state information of the window pad matching the detected incident angle based on the database.
14. A mat monitoring system, comprising:
a polishing device including a polishing platen and a polishing pad attached to an upper portion of the polishing platen and having a translucent window pad formed thereon;
an optical system disposed at a lower portion of the polishing platen, and configured to irradiate light to the window to acquire surface state information of the window pad; and
an analyzer that monitors a surface state of the polishing pad based on information acquired by the optical system.
15. The pad monitoring system of claim 14, the optical system comprising:
a fiber optic cable attached to an underside of the window pad and forming a moving path of light;
a light source connected to one side of the optical fiber cable and generating light; and
and a detection unit connected to the other side of the optical fiber cable and receiving reflected light scattered from the surface of the window pad.
16. The mat monitoring system of claim 15,
the optical fiber cable perpendicularly irradiates light generated from the light source to the window pad,
the optical system further includes a beam splitter that separates incident light irradiated to the window pad and reflected light reflected from the window pad.
17. The mat monitoring system of claim 15,
the detection unit acquires a scattered image of the reflected light,
the analyzer generates a predicted result value for the surface roughness of the polishing pad based on the scattering image.
18. The mat monitoring system of claim 14, further comprising:
a conditioning device that conditions a surface of the polishing pad; and
a control section that controls an operation of the adjustment device,
the control unit determines whether to operate the conditioning device according to the surface state of the polishing pad analyzed by the analyzer.
19. A pad monitoring method of monitoring a surface of a polishing pad, comprising:
providing a polishing pad having a translucent window pad formed thereon;
a step of irradiating light to the surface of the window pad from the side opposite to the surface of the polishing pad;
a step of receiving reflected light scattered from a surface of the window pad; and
a step of collecting a scatter image according to the received reflected light.
20. The method of claim 19, wherein the monitoring of the pad is performed by a pad monitoring device,
the step of collecting a scatter image comprises:
a step of performing image Fourier transform on the scattering image to remove noise;
and converting the scattering image with the noise removed into an index of a histogram.
21. The pad monitoring method of claim 19, further comprising:
a step of monitoring a surface state of the polishing pad through the collected scattering image,
the step of monitoring the surface condition comprises:
a step of setting a database of scattering images corresponding to the surface roughness of the window pad; and
a step of selecting surface roughness information corresponding to the collected scatter images based on the database.
22. The method of claim 21, wherein the monitoring of the pad is performed by a pad monitoring device,
the step of monitoring the surface condition further comprises:
and a step of setting a correlation coefficient for the surface roughness of the window pad and the polishing pad, and applying the correlation coefficient to the surface roughness of the selected window pad, thereby selecting information for the surface roughness of the polishing pad.
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Also Published As
| Publication number | Publication date |
|---|---|
| CN117020925A (en) | 2023-11-10 |
| KR102580487B1 (en) | 2023-09-21 |
| KR20190142571A (en) | 2019-12-27 |
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