CN117098632A - End point window with controlled textured surface - Google Patents

Abstract

A chemical mechanical polishing pad window having a controlled textured surface comprising repeated patterned features. The window is formed by providing a consistent ISRM over the lifetime of the CMP pad _max‑min The characteristic values result in improved endpoint detection and in situ rate monitoring. Furthermore, a chemical mechanical polishing pad having a window of the present application is provided.

Description

End point window with controlled textured surface

Cross Reference to Related Applications

The present application claims priority from U.S. patent application Ser. No. 63/141,368, entitled "ENDPOINT WINDOW WITH CONTROLLED TEXTURE SURFACE," filed on 25 th month 1 year 2021, in accordance with 35U.S. C. ≡119, which is incorporated herein by reference.

Technical Field

The present disclosure relates generally to chemical mechanical planarization and, more particularly, to an endpoint window having a controlled textured surface.

Background

Integrated circuits are typically formed on a substrate by sequential deposition of conductive, semiconductive and/or insulative layers on a silicon wafer. Various manufacturing processes require planarization of at least one of these layers on the substrate. For example, for certain applications (e.g., polishing a metal layer to form vias, plugs, and lines in trenches of a patterned layer), the overburden is planarized until the top surface of the patterned layer is exposed. In other applications (e.g., planarizing a dielectric layer for photolithography), the overlying layer is polished until a desired thickness remains over the underlying layer. Chemical Mechanical Planarization (CMP), which is sometimes alternatively referred to as chemical mechanical polishing, is one method of planarization. This planarization method typically involves a substrate mounted on a carrier head. The exposed surface of the substrate is typically placed against a polishing pad on a rotating platen. The carrier head provides a controllable load (e.g., an applied force) on the substrate to urge the substrate against the rotating polishing pad. A polishing liquid, such as a slurry with abrasive particles, can also be disposed on the surface of the polishing pad during polishing.

In some cases, the CMP pad may include a window to enable in situ monitoring of the polishing process. For example, a laser may travel through the window, reflect from the material being removed via CMP, and the intensity of the reflected light may be used to determine when the etching process is complete. When the reflective material (e.g., metal) is removed, the amount of light reflected from the wafer is reduced. This reduction is observed by monitoring the intensity of the laser light returning through the window over time and can be used to detect the endpoint of the etching process (i.e., determine when the reflective material is completely removed from the wafer surface).

Disclosure of Invention

The present disclosure recognizes that reliable CMP endpoint detection needs to have a window of fine-tuned initial percent transmission to the laser and that this transmission should remain as stable as possible throughout the lifetime of the pad. Previous windows for CMP pads failed to meet the requirements for accurate and reliable monitoring of polishing processes, resulting in process inefficiency and reduced yield (yield). Previous windows in CMP pads are prone to significant changes in transmission during use. For example, a diamond conditioner used as part of a CMP workflow may scratch and/or remove portions of the window surface, thereby altering the transmission of light through the window. The present disclosure recognizes that when the window thins after sustained use and/or finishing, the window is more likely to deform during use, resulting in undesirable metrology variability (which may be due to elevated ISRM _max-min Characterization quantization (see fig. 6C and table 1 and corresponding description below)). In some cases, the surface of the wafer may be scanned to determine whether to remove reflective material from a particular region of the wafer. Even when material has not been removed, the previous window may still cause variability in the light intensity measured at different areas of the wafer surface (see fig. 1C and corresponding description below). The present disclosure also recognizes that not only should the light transmission be less than a threshold level based on the property determination of the detector(s) for CMP monitoring and endpoint detection, but that the presence of repeated patterns on the surface of the window also reduces the measurement variability over time, resulting in ISRM _max-min Reduced and more consistent values of the characteristic. If the light transmission is too high, the detector(s) may become saturated and the signal may be unstable and/or unreliable. However, even if the window provides sufficiently low light transmission, this transmission property is often insufficient by itself to provide reliable measurements over the lifetime of the CMP pad (e.g., consistent ISRM _max-min Characteristic values).

The present disclosure provides improved windows for endpoint detection and in situ rate monitoring. This unique CMP pad window provides a solution to the problems of previous CMP pad window technologies, including those described above. The CMP pad window described in this disclosure has a controlled textured surface that includes repeated patterned features (e.g., unique textures on at least one surface of the window). For example, a controlled textured surface comprising repeating patterned features (e.g., micropatterned texture) may be provided on the bottom surface of the CMP pad window to diffuse (diffuse) light traveling therethrough. The repeated pattern provides a light diffusing texture. The repeated patterned features may be prepared using injection molding, laser cutting, and/or any other machining or surface patterning technique. The new CMP pad window provides reliable and reproducible removal rate monitoring and endpoint detection. The present disclosure also includes novel methods for preparing surface textures on materials used in CMP pad windows. These methods facilitate more precise tuning of window texture and transmission of light through the window, both of which are critical to providing reliable and improved performance. The method may involve injection molding, machining (e.g., CNC machining using an end mill bit of appropriate diameter, laser machining), and/or any other suitable technique.

In an embodiment, a window for a Chemical Mechanical Planarization (CMP) pad includes (e.g., is formed of) a light transmissive material. The first surface of the window has a repeating patterned texture or feature. The first surface may correspond to a bottom surface of the CMP pad (e.g., facing in the same direction as the bottom surface) that does not contact a substrate being planarized using the CMP pad during a CMP process.

Measured ISRM of the window _max-min The characteristic may be less than a threshold value (e.g., 1%, 0.5%, or 0.3%). The ISRM is provided with _max-min The characteristic may be a difference between a maximum percent intensity and a minimum percent intensity measured across a surface of a wafer comprising the reflective material. After the CMP pad is used for chemical mechanical planarization of one or more wafers for a period of time (e.g., at the end of the useful life of the CMP pad), the ISRM of the window _max-min The characteristic may vary by less than a threshold amount (e.g., 5%, 10%, 25%, or 50%).

The repeated patterned features are configured to diffuse light traveling through the window. The repeated patterned features may include regularly spaced raised features. The window may have a width and a length less than the width. The width and the length may characterize the physical dimensions of the window (e.g., whether the window has a rectangular shape, a rounded rectangular shape, an oblong shape, or any other shape). As one example, the repeated patterned features may include a first set of regularly spaced raised features parallel to the direction of the width of the window and a second set of regularly spaced raised lines angled (e.g., in the range from 20 ° to 60 °) relative to the first set of regularly spaced raised features. As another example, the repeated patterned features may include a cross-line (cross-bar) texture having a first set of regularly spaced features in the first surface at a first angle (e.g., 45 °) relative to the direction of the width of the window and a second set of regularly spaced features in the first surface at a second angle (e.g., 90 °) relative to the first set of lines, wherein the first angle is different from the second angle.

In another embodiment, a Chemical Mechanical Planarization (CMP) pad includes: a top surface that contacts a substrate being planarized using the CMP pad during a CMP process; a bottom surface opposite the top surface; and a window that allows light to travel between a top side associated with the top surface and a bottom side associated with the bottom surface. The window comprises a light transmissive material. The first surface of the window has a repeating patterned texture or feature. The first surface may correspond to the bottom surface of the CMP pad (e.g., facing in the same direction as the bottom surface) that does not contact a substrate being planarized during a CMP process using the CMP pad.

Measured ISRM of the window _max-min The characteristic may be less than a threshold value (e.g., 1%, 0.5%, or 0.3%). The ISRM is provided with _max-min The characteristic may be a difference between a maximum percent intensity and a minimum percent intensity measured across a surface of a wafer comprising the reflective material. After the CMP pad is used for chemical mechanical planarization of one or more wafers for a period of time (e.g., at the end of the useful life of the CMP pad), the ISRM of the window _max-min The characteristic may vary by less than a threshold amount (e.g., 5%, 10%, 25%, or 50%).

The repeated patterned texture or feature is configured to diffuse light traveling through the window. The repeated patterned texture may include regularly spaced raised features. The window may have a width and a length less than the width. The width and the length may characterize the physical dimensions of the window (e.g., whether the window has a rectangular shape, a rounded rectangular shape, a oblong shape, or any other shape). As one example, the repeated patterned features may include a first set of regularly spaced raised features parallel to the direction of the width of the window and a second set of regularly spaced raised lines angled (e.g., in the range from 20 ° to 60 °) relative to the first set of regularly spaced raised features. As another example, the repeated patterned features may include a cross-line texture having a first set of regularly spaced features in the first surface at a first angle (e.g., 45 °) relative to a direction of the width of the window and a second set of regularly spaced features in the first surface at a second angle (e.g., 90 °) relative to the first set of lines, wherein the first angle is different from the second angle.

Drawings

To assist in understanding the present disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a diagram of an exemplary system for Chemical Mechanical Planarization (CMP);

FIG. 1B is a diagram of a portion of the system depicted in FIG. 1A for in situ rate monitoring and endpoint detection;

FIG. 1C shows an exemplary plot of detected intensity versus wafer diameter during an exemplary CMP process using different CMP pad windows;

FIG. 2 is a diagram of an exemplary CMP pad including a window and an enlarged view of the textured surface of the window;

FIGS. 3A, 3B, and 3C are diagrams depicting exemplary surface textures of CMP pad windows;

FIG. 3D is a diagram of a cross-sectional view of a randomly textured surface at a high magnification;

FIGS. 3E, 3F, and 3G are diagrams depicting, at a high magnification, exemplary cross-sectional views of patterned textures of a CMP window;

FIG. 4 is a diagram depicting a combination of two pieces with textured surfaces for forming an exemplary window for a CMP pad;

FIGS. 5A and 5B are images of exemplary molds for injection molding to prepare windows having textured surfaces;

FIGS. 6A and 6B are graphs of the percent transmission of light at different wavelengths for different windows for a CMP pad;

FIG. 6C is an ISRM showing an exemplary CMP window after a CMP pad break-in (break-in) and at the end of pad life _max-min A bar graph of characteristic values; a kind of electronic device with high-pressure air-conditioning system

Fig. 7, 8 and 9 are flowcharts of exemplary processes for preparing CMP pad windows and CMP pads including such windows.

Detailed Description

It should be understood at the outset that although an illustrative implementation of an embodiment of the present disclosure is illustrated below, the present disclosure may be implemented using any number of techniques, whether currently known or not. The disclosure should in no way be limited to the illustrative implementations, figures, and techniques depicted below. In addition, the figures are not necessarily drawn to scale.

Chemical mechanical planarization system with endpoint detection

Fig. 1 illustrates a system 100 for performing chemical mechanical planarization. The system 100 includes a CMP pad 200 (also referred to as a "polishing pad" see also fig. 2 and corresponding description below) that is placed on the platen 102 or attached to the platen 102. For example, an adhesive layer (not shown) can be used to attach the polishing pad to the platen 102. In some cases, the platen 102 may be rotated during chemical mechanical planarization. Wafer 104 (e.g., a silicon wafer with or without conductive, semiconductive, and/or insulative layers, as described above) is attached to a head 106 of a rotatable chuck (chuck). The wafer 104 may be attached using vacuum and/or a reversible adhesive (e.g., an adhesive that holds the wafer 104 in place during chemical mechanical planarization but allows the wafer 104 to be removed from the head 106 after chemical mechanical planarization). As depicted in fig. 1, pressure may be applied to the wafer 104 during chemical mechanical planarization (e.g., to facilitate contact between the surface of the wafer 104 and the polishing pad 200).

An exemplary polishing pad 200 is depicted in fig. 2 and described in more detail below. Briefly, the polishing pad 200 generally has a circular or approximately cylindrical shape (i.e., having a top surface, a bottom surface, and curved edges). The polishing pad 200 can comprise polyurethane. The polishing pad 200 includes a window 202. Window 202 may have any suitable size for a given application. The window 202 may have specially designed textures on its top and bottom surfaces, as described in more detail below with respect to fig. 2-4. For example, window 202 may have a first texture on one surface and the same or different textures on the other surface. In some implementations, the window 202 may have a repeating patterned feature and/or roughened texture on one surface and a repeating patterned texture on the other surface (see fig. 3A-3C and corresponding description below). In some implementations, the window 202 has a roughened texture on the top surface and a repeating patterned texture on the bottom surface (see examples of fig. 3A and 3B). In some implementations, the window 202 is machined with a cross-line pattern in both the top and bottom surfaces (see the exemplary cross-line pattern depicted in fig. 3C).

The window 202 is typically disposed in or over an aperture in the CMP pad 200. As depicted in the side view depiction of fig. 2, light from laser 112 may be directed to travel through window 202. A portion of the light reflected from the reflective material 118 on the surface of the polished wafer 104 travels back through the window 202 and to the detector 114. The signal from the detector 114 is provided to a computer 116 configured to monitor the light intensity over time. The computer 116 may be configured to detect that an endpoint is reached when the intensity reaches a predefined value (e.g., or the user may monitor the graph 150 to determine when the CMP process is complete).

Fig. 1C shows an exemplary graph 150 of light intensity information as a function of wafer diameter as the wafer 104 is scanned over the window 202. Advanced microfabrication processes may require monitoring of the polishing process in terms of positional changes along the surface of the wafer 104. These surface scanning methods may be referred to as In Situ Rate Monitoring (ISRM). For example, different pressures may be applied during polishing of certain areas of the wafer surface, and the pressure may be determined based on information obtained through in situ rate monitoring. Reliable performance of these advanced polishing processes requires consistent and reliable signals that vary in dependence on position along the surface of the wafer 104. If the window 202 is functioning properly (e.g., this is facilitated, inter alia, using the uniquely textured window 202 described in this disclosure), then a uniform intensity profile 152a is initially seen and is reduced to a lower value 156a after the CMP process is complete.

The difference 154a between the maximum and minimum intensities along the surface of the wafer 104 is a relatively small value for the novel window 202 described in this disclosure. For example, the difference 154a of the windows 202 described in this disclosure may be less than a threshold value (in percent light transmission) of about 1%, 0.5%, 0.1%, or less. The difference 154a may be stable throughout the life of the window 202 (see fig. 6C and table 1 below). This difference 154a is referred to in this disclosure as an in situ rate monitoring min/max characteristic (ISRM) _max-min Characteristics). This relatively small variation (i.e., based on the small difference 154 a) facilitates the use of advanced processing techniques to actively control the polishing removal rate in different areas or regions of the wafer surface. In contrast, the previous window may have a non-constant intensity profile 152b that decreases over time during polishing (see profile 156b after polishing completion for the previous CMP pad window). The difference 154b between the maximum and minimum intensities along the surface of the wafer 104 is a relatively large value for the previous window 202 such that advanced CMP processes cannot be reliably performed.

Returning to fig. 1A, the polishing pad 200 can have any suitable thickness and any suitable diameter (e.g., to be employed with a CMP system, such as the system 100 described above). For example, the thickness of the polishing pad 200 can range from less than or about 0.5 millimeters (mm) to greater than 5 centimeters (cm). In some embodiments, the thickness of the polishing pad 200 can be in the range from 1mm to 5 mm. The polishing pad diameter is typically selected to match or be just smaller than the diameter of the platen 102 of the polishing system 100 being used. The polishing pad 200 typically has a uniform or nearly uniform thickness (e.g., a thickness that varies by no more than 50%, 25%, 20%, 10%, 5% or less across the radial extent of the polishing pad).

Slurry 108 can be provided on the surface of polishing pad 200 prior to and/or during chemical mechanical planarization. Slurry 108 may be any suitable slurry for planarization of the wafer type and/or layer material to be planarized (e.g., removal of silicon oxide layer from the surface of wafer 104). Slurry 108 typically comprises a fluid and abrasive and/or chemically reactive particles. Any suitable slurry 108 may be used. For example, the slurry 108 may react with one or more materials removed from the planarized surface. The conditioner 110 is a device configured to condition the surface of the polishing pad 200. During chemical mechanical planarization, the conditioner 110 typically contacts the surface of the polishing pad 200 and removes portions of the top layer of the polishing pad 200 to improve its performance. For example, the conditioner 110 may roughen the surface of the polishing pad 200.

As described in more detail below, the uniquely textured window 202 described in the present disclosure reduces or eliminates changes in light transmission through the window after contact with the slurry 108, wafer 104, and/or conditioner 110. For example, the bottom surface of window 202 may have repeated patterned features, such as repeated patterned textures depicted in fig. 6E-6G and described in more detail below. This repeated patterning feature may facilitate consistent measurements and ISRM throughout the life of the CMP pad 200 _max-min Low values of the characteristics. For example, even if the CMP pad 200 and window 202 become thinner during use, resulting in possible movement and/or bending of the window 202, using the novel window 202, isrm of the present disclosure _max-min The characteristics remain the same (see also table 1 and fig. 6C and corresponding description below). As another example, the texture of the top surface of the window 202 (i.e., the surface exposed during use of the CMP pad 202) may have a texture that mimics the texture created by contact with the conditioner 110, slurry 108, and/or wafer 104.

Exemplary polishing pad with improved window

Fig. 2 illustrates an exemplary CMP pad 200 in more detail. The CMP pad 200 includes a top surface 204 that contacts material during the CMP process, a bottom surface 206, and a window 202 on or within the pores of the CMP pad 200. The CMP pad 200 generally has a circular or approximately cylindrical shape. The thickness 208 of the CMP pad 200 may range from about 1mm to about 10mm or more. The diameter of the CMP pad 200 may range from about 500mm to about 800 mm. The CMP pad 200 generally has a uniform thickness 208. A uniform thickness is defined as a thickness that varies by no more than 50%, 25%, 20%, 10%, 5% or less across the radial extent of the pad 200. In other words, the thickness measured near the center of the pad 200 is substantially the same as the thickness near the edge of the pad 200.

The CMP pad 200 may be formed of a thermoset material (such as polyurethane) or any other suitable material. The top surface 204 may include trenches or any other suitable structure or pattern for facilitating CMP (see enlarged view 210). For example, the trenches may facilitate transporting the material being polished and/or any other products of the CMP process away from the surface 204 of the CMP pad 200 and the wafer 104 being planarized. The CMP pad 200 includes a window 202 on or in the aperture of the CMP pad 200. The window 202 may be formed of a thermoset or thermoplastic material, such as polyurethane, polyethylene terephthalate glycol, cyclic olefin copolymer, or any other suitable material (i.e., a material that is suitably light transmissive (see fig. 6A and 6B) and moldable/machinable to prepare the textured surface 220, 222). The window 202 may be positioned at any suitable location in the CMP pad 200. The window 202 may have any suitable size for viewing portions of the wafer 104 during the CMP process (see fig. 1A and 1B for reference).

An enlarged top view 210 of window 202 shows a top surface 220 of window 202. The top surface 220 may have a unique texture, as described in more detail below with respect to fig. 3A and 3C. For example, the top surface 220 may have a roughened texture (see fig. 3A and 3D). The roughened texture may be achieved through a random roughening process such as sanding, treatment with a conditioner (see fig. 1A), sandblasting, or the like. The roughened texture may correspond to an average surface roughness in the range from 1 to 50 micrometers or in some cases, in the range from about 2 to 10 micrometers. As another example, the top surface 220 may have a repeating patterned texture, such as a cross-line patterned texture (e.g., see fig. 3C, 3F, 3G), a "wave" patterned texture (e.g., see fig. 3E), or any other suitable texture.

The enlarged bottom view 212 of the window 202 shows the bottom surface 222 of the window 202. The bottom surface 222 may have a controlled texture including repeated patterned features for diffusing light traveling through the window 202. For example, the bottom surface 222 may have a texture that includes repeated patterned features and an optionally roughened texture (see fig. 3B). For example, the bottom surface 222 may have cross-line patterned features (see fig. 3C), a "wave-like" patterned texture, or any other suitably controlled texture. Further examples of patterned textures are depicted in fig. 3D-3G and described below. The texture of top surface 220 may be the same as or different from the texture of bottom surface 222. While the example of fig. 2 describes the top surface 220 of the window 202 as corresponding to the top surface 204 of the CMP pad 200 (i.e., facing in the same direction as the top surface 204 of the CMP pad 200) and the bottom surface 222 of the window 202 as corresponding to the bottom surface 206 of the CMP pad 200 (i.e., facing in the same direction as the bottom surface 206 of the CMP pad 200), it should be understood that the direction of the window 202 may vary. For example, the orientation of the window 202 may be reversed such that the top surface 220 of the window 202 faces the direction of the bottom surface 206 of the CMP pad 200.

Fig. 3A shows an exemplary top surface 220 of window 202. In the example of fig. 3A, top surface 220 has roughened texture 302. The roughened texture may have an average roughness in the range from about 1 to 50 micrometers or in some cases, in the range from about 2 to 10 micrometers. The exemplary top surface 220 of fig. 3A may be prepared using injection molding (see fig. 5B), machining, treatment with an abrasive, or any other suitable process. In some cases, the use of injection molding may provide improved consistency between different window preparations at relatively low manufacturing costs. For example, texture 302 of top surface 220 may be a randomly roughened texture 340 shown in fig. 3D. Roughened texture 340 depicts a portion of a cross-section through a randomly roughened surface, such as top surface 220 of fig. 3A. The random roughening texture 340 has random features 342 randomly distributed on the surface (e.g., on the top surface 220). The random features 342 may have sizes 344a, 344b (e.g., in width and/or height/depth, as shown in fig. 3D) in a range from about 1 to 50 microns, or in some cases, in a range from about 2 to 10 microns.

Fig. 3B depicts an exemplary bottom surface 222 of window 202. In the example of fig. 3B, the bottom surface 222 may be provided with regions having controlled textures 304 and regions having different textures 320. The region with texture 304 may be a region (having a width 316 and a length 318) through which light from laser 112 travels during in-situ rate monitoring/endpoint detection (see fig. 1A-1C and corresponding description above). For example, all or a portion of the region having the controlled texture 304 may be aligned over the pores of the CMP pad 200 such that light travels through this textured region. The texture 304 of the bottom surface 222 may include a repeating pattern designed to diffuse light traveling through the window 202. At the same time, the remaining surface area with texture 320 may be placed on a portion of pad 200 or in contact with a portion of pad 200 to aid in the attachment of window 202 to pad 200. The length 318 and width 316 of the region with texture 304 may be any suitable values for a given in-situ rate monitoring/endpoint detection application. As a non-limiting example, the length 318 may be about 50 millimeters (e.g., 2 inches) and the width 314 may be 13 millimeters (0.5 inches).

In an exemplary embodiment, the texture 304 through which light travels for in situ rate monitoring/endpoint detection includes a repeating pattern of regularly spaced features 306 (e.g., peaks of grooves/cups (rough/cup) 352 of fig. 3E or rounded ridges 362 of fig. 3F, 3G). Feature 306 may be straight, as shown. In some cases, feature 306 may be curved or may have any other suitable shape or design. Feature 306 may be raised relative to surface 222 or at a depth below surface 222. More generally, the average height of the surface 222 may be convex, concave, or approximately coplanar with the features 306. For example, features 306 may have a height or depth in a range from about 25 microns to about 500 microns (e.g., 0.001 inches to about 0.02 inches). The first set of features 306 may be parallel to the direction of the width 316 of the window 202 (as shown in the example of fig. 3B), or at any other suitable angle (see fig. 3C). Feature 306 may have a width in a range from about 25 microns to about 500 microns (e.g., 0.001 inches to about 0.02 inches). The distance 308 between adjacent features 306 (e.g., the pitch of the repeated patterned features 306) may be in the range from about 120 microns to about 750 microns (e.g., 0.005 to about 0.03 inches).

Fig. 3E shows an example of a controlled texture including repeated patterned features 350. The repeated patterned features 350 of fig. 3E may be referred to as "wavy" features. Fig. 3E depicts a portion of a cross-section through a surface having repeated patterned features 350, such as bottom surface 222 of fig. 3B or 3C. For example, the repeated patterned feature 350 may be the texture 304 of fig. 3B or the texture 322 of fig. 3C. For example, feature 352 may correspond to features 306, 310 of fig. 3B or features 324, 330 of fig. 3C. The repeated patterned features 350 have regular features 352, the regular features 352 being grooves or cups formed (e.g., via machining or any other suitable method) on the surface. In some implementations, the repeated patterned features 350 are also roughened such that they also include roughened features similar to the roughened features described above with respect to fig. 3D (see also fig. 3G, which shows examples of combinations of repeated patterned features and roughened textures). The width 354 of the repeated patterned features 350 may be any suitable value. As an example, the width 354 may be in a range from about 0.1 millimeters to about 0.5 millimeters. The depth 356 of the feature 352 may be any suitable value. As an example, the depth 356 may be in a range from about 2 microns to about 100 microns.

Fig. 3F and 3G show other examples of controlled textures that include repeated patterned features 360 and 370, respectively. The repeated patterned features 360 and 370 of fig. 3F and 3G may be referred to as rounded ridge features. Fig. 3F and 3G illustrate portions of a cross-section through a surface having repeated patterned features 360 and 370, such as bottom surface 222 of fig. 3B or 3C. For example, the repeated patterned features 360 and 370 may be texture 304 of FIG. 3B or texture 322 of FIG. 3C. For example, feature 362 may correspond to features 306, 310 of fig. 3B or features 324, 330 of fig. 3C. The repeated patterned features 360 and 370 have regular features 362, the regular features 362 being ridges formed on the surface (e.g., via injection molding or any other suitable method). Texture 370 of fig. 3G is also randomly roughened (e.g., the same or similar as described above with respect to fig. 3D). The width 364 of the feature 362 may be any suitable value. As an example, the width 364 may be in a range from about 0.1 millimeters to about 0.5 millimeters. The spacing 366 between adjacent features 362 may be any suitable value. As an example, the spacing 366 may be in a range from about 0.1 millimeters to about 0.5 millimeters. The spacing 366 may be the same or different than the width 364. The height 368 of the features 362 may be any suitable value. As an example, the height 368 may be in a range from about 25 microns to about 500 microns.

The optional second set of features 310 may be angled 314 (e.g., 20 ° to 90 °) relative to the first set of features 306. The second set of features 310 may be straight, curved, or any other suitable shape or design, for example, as described above with respect to fig. 3E-3G. For example, angle 314 may be about 60 ° or any suitable angle. The repeated patterned features 310 may have the same or different heights/depths, widths, and spacings 312 as those described above for features 306.

Still referring to fig. 3B, texture 320 may be any texture. For example, texture 320 may be the same or similar roughened texture as described above with respect to fig. 3A. In some cases, texture 304 may include both repeated patterned features 306, 310 and roughened textures (see, e.g., fig. 3G). The exemplary bottom surface 222 of fig. 3B may be prepared using injection molding (see fig. 5A), machining, and/or any other suitable process.

Fig. 3C shows another example of a controlled texture of the top surface 220 and/or the bottom surface 222 of the window 202. The exemplary surfaces 220, 222 include a controlled texture 322, the controlled texture 322 including a cross-line pattern of repeating features 324 and 330. Features 324 and 330 may be the same as or similar to features 306 and 310 described above (e.g., any of the exemplary features shown in the patterned texture of fig. 3E-3G and described above). Features 324 and 330 may be straight or curved. The features 324, 330 may be machined in the surfaces 220, 222 and/or prepared using injection molding. The features 324, 330 may have any suitable depth and/or height. As an example, the features 324, 330 may have a depth/height of about 25 microns to about 500 microns (e.g., 0.001 inches to about 0.02 inches). The features 324, 330 may have any suitable width. As an example, the features 324, 330 may have a width of about 120 microns to about 750 microns (e.g., 0.005 inches to about 0.03 inches). The distance 326, 332 between adjacent features 324, 330 may be any suitable value. As an example, the distance 326, 332 between adjacent features 324, 330 may be in a range from about 120 microns to about 750 microns (e.g., 0.005 inches to about 0.03 inches). The first set of features 324 may be angled 328 (e.g., 45 °) relative to a direction of the width of the window 202. The second set of features 330 may be angled 334 (e.g., 90 °) relative to the first set of features 324. The exemplary surfaces 220, 222 of fig. 3C may be prepared by machining (e.g., using CNC milling (milling), laser machining, or the like, with ends of appropriate diameters).

The patterned features illustrated in fig. 3A-3G are merely exemplary. The window 202 may generally include any combination of the surfaces 220, 222 and/or the textures 302, 304, 320, 322, 340, 350, 360, 370 described above with respect to fig. 3A-3G. For example, the top surface 220 may have the roughened texture 302 of fig. 3A and/or the repeated patterned texture 322 of fig. 3C. Meanwhile, the bottom surface 222 may include the patterned texture 304 of fig. 3B or the patterned texture 322 of fig. 3C. The present disclosure contemplates the use of any other suitable patterned features and/or textures to facilitate reliable fabrication of windows 202 having consistent light transmission properties and long lifetime for monitoring CMP processes. For example, the bottom surface 222 may include one or more of a wavy texture or the like.

The depth of the machined and/or injection molded features (see fig. 3B, 3C, 3E, 3F, and 3G) may be adjusted to improve light transmission properties to improve monitoring of the CMP process (e.g., for endpoint detection). For example, the depth of the machined cut used to achieve the cross-line feature of fig. 3C may be adjusted to achieve a desired light transmission at a given wavelength and/or to provide the ISRM described above with respect to fig. 1C _max-min Desirable values of the characteristics. In some implementations, the depth/height of the features is selected such that the light transmission properties of the window 202 remain relatively constant even if portions of the surface of the window 202 are removed during the CMP process and/or if the window 202 is deformed or moved during the CMP process. For example, making the depth of cut used during machining greater than 120 microns (e.g., about 0.005 inches) mayIs beneficial. In some embodiments, the depth of cut used during machining (or the depth of features prepared using injection molding) may be in the range from about 25 microns to about 75 microns (e.g., 0.001 inch to 0.003 inch). In some cases, varying the depth of cut along the machined surfaces 220, 222 may provide further control over the transmission of light through the window 202.

In some embodiments, separate components may be prepared such that one component includes top surface 220 and the other component includes bottom surface 222. Fig. 4 illustrates such an embodiment in which a first member 402 including a top surface 220 is disposed on a second member 404 including a bottom surface 222 to form a window 202. The components 402 and 404 may be attached using an adhesive (e.g., a pressure sensitive adhesive). In some cases, the components 402 and 404 may be chemically bonded to form the window 202 (e.g., in the presence of heat and/or an appropriate adhesion promoter (adhesion promoter)). The window 202 may be disposed in or over the aperture in the pad 200 with or without the use of an adhesive such that light traveling through the aperture also travels through the window 202. In some embodiments, the window 202 is chemically bonded to the CMP pad 200.

Exemplary mold for injection molded windows

Fig. 5A and 5B illustrate exemplary molds 502 and 510 used in an injection molding apparatus 500 for preparing surfaces 222 and 220, respectively. The mold 502 for preparing the bottom surface 222 includes an inverted representation (inverted representation) of the textures 304, 320 described above with respect to fig. 3B. Region 504 of mold 502 corresponds to the region of bottom surface 222 of fig. 3B having texture 304. Region 506 corresponds to the region of bottom surface 222 of fig. 3B having texture 320. The mold 502 may include ejector pins that assist in removing the formed part from the device 500. The mold 510 for preparing the top surface 220 of the window 202 includes an inverted representation of the surface 220 described above with respect to fig. 3A. The mold 510 may be sandblasted to obtain an appropriate roughened texture (e.g., the random roughened texture 340 of fig. 3D for texture 320 or the repeated patterned textures 350, 360, 370 of fig. 3E-3G for texture 304). During injection molding, a single part may be formed with both top and bottom surfaces on opposite sides of the part, or separate parts may be prepared and combined as described above with respect to fig. 4 and below with respect to fig. 8.

Transmission of light through different windows of a CMP pad

Fig. 6A and 6B show graphs 600 and 610, respectively, of the transmission of light at various wavelengths through different windows, including various control windows (controls 1-4 and controls a-B) employing previous techniques, samples with a single random textured surface (single textures 1-6 and single textures a-C), and new techniques disclosed herein (samples 1-4 and samples a-E) with controlled textures including repeated patterned features on at least the bottom surface. The percent transmittance was measured at 633nm using a Thermo-Fisher Genesys 10 sUv-visible light spectrometer. As described above, the present disclosure recognizes that the transmission of light through window 202 should be within a threshold range 602 that ensures that the signal reaching detector 114 (see fig. 1B) is suitable for reliable monitoring of the CMP process. Threshold range 602 may be less than 20%. In some cases, the threshold may range from 5% to 15% at about 630 nm. Different threshold ranges may be selected for different applications, e.g., depending on the nature of the detector 114 (see fig. 1A) for in situ rate monitoring/endpoint detection, and the texture of the top surface 220 and the bottom surface 222 may be adjusted accordingly.

As also recognized herein, there is an ISRM that does not significantly change over the life of the CMP pad _max-min A continuously low value of the characteristic is important. This cannot be achieved solely by achieving the target transmission range and further improved properties of the CMP window are also required. For example, at least some of the contrast windows shown in fig. 6A and 6B display light transmission in the target transmission. However, these control windows employing prior art fail to provide consistently low ISRM over the life of the CMP pad _max-min The characteristics are described further below with respect to fig. 6C and table 1.

FIG. 6C shows ISRM of two previously available CMP windows (controls 1 and 2) and two CMP windows with repeated patterned texture of the present disclosure (novel windows 1 and 2) _max-min Values of the characteristics. After the CMP pad is worn in (e.g., after conditioning as described above with respect to figure 1A),novel window having ISRM lower than control window _max-min Values of the characteristics. At or near the end of pad life (e.g., after the CMP pad is no longer available for CMP processes, such as after the top layer of the pad is completely removed and/or after about 0.5 millimeters of the top surface of the CMP pad and/or CMP window is removed), the control window has an ISRM _max-min A significantly increased value of the characteristic. Pad end of life may be defined as the time at which the pad wears to 20% of the remaining lower initial groove depth. ISRM of control 1 _max-min The characteristic increases by about 190% (i.e., from 0.75 to 1.105). ISRM of control 2 _max-min The characteristic increases by about 160% (i.e., from 0.75 to 1.955). In contrast, ISRM of novel window _max-min The characteristics did not increase significantly from post break-in to the end of pad life. ISRM of novel window 1 _max-min The characteristic increases by about 5% (i.e., from 0.275 to 0.29). ISRM of novel window 1 _max-min The characteristic increases by about 90% (i.e., from 0.15 to 0.21). ISRM of novel window in whole pad life _max-min The value of the characteristic is also kept in a target range of less than 0.5% (or lower).

The novel window samples with controlled texture described in this disclosure (samples 1-4 and a-D of fig. 6A and 6B and novel windows 1 and 2 of fig. 6C) have not only percent transmission values within this threshold range 602 but also repeated patterning features (see, e.g., fig. 3A-3G and corresponding description above). These samples have more reliable and reproducible transmission properties and ISRM than can be achieved using previous techniques _max-min Characteristics. Thus, the novel window samples described in this disclosure perform better than previous windows for CMP pads and can be prepared using a more reliable and cost-effective process (see fig. 7-9).

Method of preparing textured surface and textured window for CMP pad

Fig. 7 illustrates a process 700 for preparing window 202. The process 700 generally facilitates the preparation of windows 202 having improved light transmission properties and increased lifetime. The process 700 may begin at step 702 where the first textured surface 220 is prepared. The first textured surface 220 can be prepared using injection molding and/or any suitable machining process, such as CNC machining using an end mill (endmill), laser machining, or the like. For example, an uncured thermoset material can be introduced into an injection molding machine to contact a mold (e.g., mold 510 of fig. 5B) to prepare first textured surface 220. In some embodiments, one component can be obtained (e.g., commercially available transparent components) and one surface of the component can be treated or machined with an abrasive to produce the first textured surface 220.

At step 704, a second surface 222 is prepared on the opposite side of the component from step 702. If injection molding is used to prepare the first textured surface 220 at step 702, the second textured surface 222 can be prepared during the same injection molding process (e.g., using the mold 502 of fig. 5A as the mold for the second textured surface 222). As another example, the second textured surface 222 may be prepared using any suitable machining process.

At step 706, the window 202 from step 704 is disposed in or over the aperture in the CMP pad 200 such that light traveling through the aperture also travels through the window 202. The window 202 may be attached to the CMP pad 200 using an adhesive (e.g., a pressure sensitive adhesive) or without an adhesive (e.g., using ultrasonic welding or any other suitable technique). For example, the window 202 may be attached to the top pad portion or sub-pad (subpad) portion of the CMP pad 200 using an adhesive or via soldering. In some embodiments, the window 202 is chemically bonded to the CMP pad 200 (e.g., in the presence of heat and/or an appropriate adhesion promoter).

As an illustration of the attachment of the window of the present invention to the polishing pad, the following process may be used. A recess or pocket may be formed in the top pad using CNC or similar methods. The dimensions of the recess will correspond to the dimensions of the window to be installed. Thus, the size of the grooves can vary, but the grooves do not extend the entire thickness of the top pad. In other words, the grooves do not form apertures through the top pad. The subpad is then laminated or otherwise adhered to the top pad. Holes are then punched through the top pad and subpad at the grooves, with the holes being sized such that a flange is formed from the remaining top pad material and underlying subpad material. A window is then mounted in the recess on top of the hole, forming an optical detection port or window in the pad. This illustrates one embodiment of the window of the present invention being mounted into a polishing pad.

Fig. 8 depicts an exemplary process 800 for preparing the window 202 by combining a first component having a first textured surface 220 (e.g., component 402 of fig. 4) and a second component having a second textured surface 222 (e.g., component 404 of fig. 4). The process 800 generally facilitates the preparation of windows 202 having improved light transmission properties and increased lifetime. The process 800 may begin at step 802 where a first window component (e.g., component 402 of fig. 4) having a first textured surface 220 is prepared. The first component may be prepared using injection molding and/or any suitable machining (e.g., CNC machining using an end mill). For example, uncured thermoset material can be introduced into an injection molding machine to contact a mold (e.g., mold 510 of fig. 5B) to prepare a first part using injection molding. The component may be further machined to produce any further desirable texture features. The method 900 described below with respect to fig. 9 may be used to prepare the first component using injection molding and/or machining. In some embodiments, one component may be obtained (e.g., commercially available transparent components) and the component may be machined to produce the first textured surface 220.

At step 804, a second window component (e.g., component 404 of fig. 4) having a second textured surface 222 is prepared. May be prepared using the same or similar methods as described above for preparing the first component having the first textured surface 220 at step 802. The second component may be prepared using injection molding and/or any suitable machining (e.g., CNC machining using an end mill). For example, uncured thermoset material can be introduced into an injection molding machine to contact a mold (e.g., mold 502 of fig. 5A) to produce a second part using injection molding. The second component may be further machined to produce any further desirable texture features on the second textured surface 222. The method 900 described below with respect to fig. 9 may be used to prepare the second component using injection molding and/or machining. In some embodiments, one component may be obtained (e.g., commercially available transparent components) and the component may be machined to produce the second textured surface 222.

At step 806, a first component having a first textured surface 220 is disposed on a second component having a second textured surface 222 (e.g., attached to the second component having the second textured surface 222). The two components are typically combined such that the first surface 220 is exposed and faces in a first direction (e.g., toward the top of the window 202) and the second surface 222 is exposed and faces in a second direction opposite the first direction (e.g., toward the bottom of the window 202). The first and second components may be attached using an adhesive (e.g., a pressure sensitive adhesive) or without an adhesive to form the window 202. In some cases, the first and second components may be chemically bonded to form the window 202 (e.g., in the presence of heat and/or an appropriate adhesion promoter).

At step 808, the window 202 from step 806 is disposed in or over the aperture in the CMP pad 200 such that light traveling through the aperture also travels through the window 202. The window 202 may be attached to the CMP pad 200 using an adhesive (e.g., a pressure sensitive adhesive) or without an adhesive (e.g., using ultrasonic welding or any other suitable technique). For example, the window 202 may be attached to the top pad portion or subpad portion of the CMP pad 200 using an adhesive or via soldering. In some embodiments, the window 202 is chemically bonded to the CMP pad 200 (e.g., in the presence of heat and/or an appropriate adhesion promoter).

Fig. 9 depicts an exemplary method 900 for preparing a controlled textured surface (e.g., surfaces 220, 222 described above). The method 900 may begin at step 902 where injection molding is performed to prepare a component (e.g., the components 402, 404 of fig. 4) having the textured surface 220, 222. For example, uncured thermoset material can be introduced into an injection molding machine to contact a mold (e.g., mold 502, 510 of fig. 5A, 5B) to prepare the part using injection molding. At step 904, a determination is made as to whether the component textured surface 220, 222 should have further texture features, such as one of the patterned features depicted in fig. 3A, 3B, 3C, or the like. If no additional features are needed, the process 900 is complete. However, if further features are desired, then the further features are machined at step 906 (e.g., using CNC machining with end mill).

Examples

This example demonstrates the performance of the window of the present invention compared to a window that does not have a controlled texture (repeated patterned texture) that includes repeated pattern features.

Using ISRM measured after the break-in period and again at the end of pad life _max-min The change in characteristics evaluates four different windows in terms of performance. Pad end of life is defined as the time at which the pad wears to 20% of the remaining lower initial groove depth. Four windows are a) IC1010 pads having windows, a hard thermoset polyurethane with a hardness of about 70 shore D, commercially available from Rohm and Haas Electronic Materials; b) An E6088 mat having a soft thermoplastic polyurethane with a hardness of about 55 shore D, commercially available from CMC Materials inc; c) An E6088 mat having a window of the invention with controlled repeating pattern texture from CNC machining, thermoplastic polyurethane with a hardness of 75 shore D; and D) an E6088 pad having a window of the invention with controlled repeating pattern texture from injection molding, thermoplastic polyurethane with a hardness of 75 shore D. Windows a) and B) do not have a controlled textured surface comprising repeated patterned features.

All pads described above were given the same break-in period, including 30 minutes of conditioning using a2813 conditioner from 3M with deionized water at 5 pounds pressure. After the break-in period, ISRM was measured under the same conditions for each window while polishing a copper wafer using a copper CMP polishing slurry at 2.5psi and 80rpm platen speed _max-min Characteristics. Endpoint detection started about 20 seconds after the start of polishing and the recording consisted of about 60 traces (trace). Calculating ISRM for four windows _max-min The characteristics and they are shown in the table below. Performing a second ISRM on the same pad at the end of pad life _max-min And measuring characteristics. Re-computing ISRM _max-min The characteristics and they are shown below in table 1.

Table 1: ISRM of example CMP Window _max-min Values of characteristics

	ISRM max-min (％)	ISRM max-min (％)
				Window	Post-running-in	Pad end of life	Changing
A	0.380	1.105	0.725％
				B	0.750	1.955	1.205％
C	0.275	0.290	0.015％
				D	0.150	0.210	0.060％

As can be seen in the table above, the window of the present invention ranges from post-wear-in period to end of pad life ISRM when compared to commercial pad window _max-min Is significantly different.

Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein. Components of the system and apparatus may be integrated or separated. Moreover, the operations of the system and apparatus may be performed by more, fewer, or other components. The method may include more, fewer, or other steps. Additionally, the steps may be performed in any suitable order. Additionally, the operations of the system and apparatus may be performed using any suitable logic. As used in this document, "each" refers to each component of a group or each component of a subset of a group.

Herein, "or" is inclusive and non-exclusive unless explicitly indicated otherwise or otherwise indicated by the background. Thus, herein, "a or B" means "A, B or both" unless explicitly indicated otherwise or otherwise indicated by the background content. Further, "and" is both common and separate unless explicitly indicated otherwise or otherwise indicated by the background. Thus, herein, "a and B" means "a and B, collectively or individually," unless indicated otherwise explicitly or otherwise indicated by the context.

The scope of the present disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the illustrative embodiments described or illustrated herein that will be understood by those of ordinary skill in the art. The scope of the present disclosure is not limited to the exemplary embodiments described or illustrated herein. Moreover, although the disclosure describes and illustrates embodiments herein as including particular components, elements, features, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated herein as would be understood by one of ordinary skill in the art. Furthermore, references in the appended claims to a device or system or a component of a device or system being adapted, arranged, capable, configured, enabled, operable, or operative to perform a particular function encompass the device, system, component whether or not it is activated, turned on, or unlocked, or that particular function, so long as the device, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Additionally, although the present disclosure describes particular embodiments as providing particular advantages, particular embodiments may not provide these advantages, provide some or all of these advantages.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the claims.

Claims (20)

1. A window for a Chemical Mechanical Planarization (CMP) pad, the window comprising a light transmissive material, wherein a first surface of the window has a controlled textured surface comprising repeated patterned features.

2. The window of claim 1, wherein the first surface corresponds to a bottom surface of a CMP pad that does not contact a substrate being planarized during a CMP process using the CMP pad.

3. The window of claim 1, wherein the repeated patterned features are configured to diffuse light traveling through the window.

4. The window of claim 1, wherein the repeated patterned features comprise regularly spaced raised features.

5. The window of claim 4, wherein the repeating patterned features comprise a cross-line pattern.

6. The window of claim 4, wherein the repeated patterned features comprise rounded ridges.

7. The window of claim 5, wherein the rounded ridges are randomly roughened.

8. The window of claim 2, wherein a second surface opposite the first surface corresponds to a top surface capable of contacting a substrate being planarized using the CMP pad during a CMP process, wherein the top surface has a roughened texture corresponding to an average surface roughness in a range from about 1 to about 50 microns.

9. The window of claim 1, wherein:

the window has a width and a length less than the width, wherein the width and the length characterize a physical dimension of the window; and is also provided with

The repeated patterned features include:

a first set of regularly spaced raised features parallel to the direction of the width of the window; a kind of electronic device with high-pressure air-conditioning system

A second set of regularly spaced raised lines angled with respect to the first set of regularly spaced raised features.

10. The window of claim 1, wherein:

the window has a width and a length less than the width, wherein the width and the length characterize a physical dimension of the window; and is also provided with

The repeated patterned features include a cross-line texture comprising:

a first set of regularly spaced features in the first surface at a first angle relative to the direction of the width of the window; a kind of electronic device with high-pressure air-conditioning system

A second set of regularly spaced features in the first surface at a second angle relative to the first set of lines, wherein the first angle is different from the second angle.

11. A Chemical Mechanical Planarization (CMP) pad comprising:

a top surface that contacts a substrate being planarized using a CMP pad during a CMP process;

a bottom surface opposite the top surface; a kind of electronic device with high-pressure air-conditioning system

A window allowing light to travel between a top side of the CMP pad associated with the top surface and a bottom side of the CMP pad associated with the bottom surface, the window comprising a light transmissive material, wherein a first surface of the window has repeated patterned features.

12. The CMP pad of claim 11 wherein the first surface of the window faces in the same direction as the bottom surface of the CMP pad, the bottom surface not contacting a substrate being planarized using the CMP pad during a CMP process.

13. The CMP pad of claim 11 wherein the repeated patterned features are configured to diffuse light traveling through the window.

14. The CMP pad of claim 11 wherein the repeated patterned features comprise regularly spaced raised features.

15. The CMP pad of claim 11 wherein the repeated patterned features comprise a cross-line pattern.

16. The CMP pad of claim 11 wherein the repeated patterned features comprise rounded ridges.

17. The CMP pad of claim 16 wherein the rounded ridges are randomly roughened.

18. The CMP pad of claim 11 wherein a second surface opposite the first surface corresponds to a top surface capable of contacting a substrate being planarized using the CMP pad during a CMP process, wherein the top surface has a roughened texture corresponding to an average surface roughness in the range from about 1 to about 50 microns.

19. The CMP pad of claim 11 wherein:

the window has a width and a length less than the width, wherein the width and the length characterize a physical dimension of the window; and is also provided with

The repeated patterned features include:

a first set of regularly spaced raised features parallel to the direction of the width of the window; a kind of electronic device with high-pressure air-conditioning system

A second set of regularly spaced raised lines angled with respect to the first set of regularly spaced raised features.

20. The CMP pad of claim 11 wherein:

the window has a width and a length less than the width, wherein the width and the length characterize a physical dimension of the window; and is also provided with

The repeated patterned features include a cross-line texture comprising:

a first set of regularly spaced features in the first surface at a first angle relative to the direction of the width of the window; a kind of electronic device with high-pressure air-conditioning system

A second set of regularly spaced features in the first surface at a second angle relative to the first set of lines, wherein the first angle is different from the second angle.

A window as disclosed herein.