Polishing pad and method for manufacturing polished workpiece

Abstract

To provide an abrasive pad with excellent surface smoothness, and a polished product manufacturing method with use thereof.SOLUTION: An abrasive pad has a polishing layer, and an end point detection window provided in an opening of the polishing layer. In the abrasive pad, when a free induction attenuation curve of spin-spin relaxation of 1H, which is obtained by measuring by Solid Echo method with use of pulse NMR, is waveform-separated into three curves derived from three components of a crystal phase, an intermediate phase, and an amorphous phase in order of shorter relaxation time, a ratio of an abundance ratio Lw20 of the amorphous phase of the end point detection window to an abundance ratio Lp20 of the amorphous phase of the polishing layer (Lp20 / Lw20) at 20°C is 0.5 to 2.0, and a ratio of an abundance ratio Sw80 of the crystal phase of the end point detection window to an abundance ratio Sp80 of the crystal phase of the polishing layer (Sp80 / Sw80) at 80°C is 0.5 to 2.0.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing pad and a method for producing a polished product using the same. [Background technology]

[0002] In semiconductor manufacturing processes, chemical mechanical polishing (CMP) is used for planarization after insulating film deposition and for forming metal wiring. One of the important technologies required for chemical mechanical polishing is polishing endpoint detection, which detects whether the polishing process is complete. For example, over-polishing or under-polishing relative to the target polishing endpoint directly leads to product defects. Therefore, in chemical mechanical polishing, the amount of polishing must be strictly controlled by polishing endpoint detection.

[0003] Chemical mechanical polishing is a complex process, and the polishing speed (polishing rate) varies depending on the operating conditions of the polishing equipment, the quality of consumables (slurry, polishing pads, dressers, etc.), and variations in conditions over time during the polishing process. Furthermore, in recent years, the precision of remaining film thickness and in-plane uniformity required in semiconductor manufacturing processes have become increasingly strict. For these reasons, detecting the polishing endpoint with sufficient precision has become more difficult.

[0004] The main methods for detecting the polishing endpoint include the optical endpoint detection method, the torque endpoint detection method, and the eddy current endpoint detection method. In the optical endpoint detection method, the endpoint is detected by irradiating the wafer with light through a transparent window member provided on the polishing pad and monitoring the reflected light.

[0005] As an example of a polishing pad that uses such an optical endpoint detection method, Patent Document 1 discloses a polishing pad that has a pad body and a transparent window member formed integrally with a part of the pad body, and in this polishing pad, the surface of the window member is recessed from the surface of the pad body, with the aim of providing a polishing pad that can prevent slurry from accumulating in the grooves of the window member and thereby improve the accuracy of polishing rate detection. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-001647 Summary of the Invention [Problem to be solved by the invention]

[0007] One method for manufacturing a polishing pad having the above-mentioned window is to fill a resin composition with a window member fixed in a mold, harden the resin composition, slice the resulting cured product, and then perform a dressing treatment. Here, the window member and the cured product of the resin composition are made of different materials, so their physical properties are quite different. For example, when slicing, there is a risk that the window portion will be dented or cracked. Furthermore, when performing a dressing treatment, there is a risk that the window portion will be dented due to the difference in the amount of wear between the window portion and the polishing layer.

[0008] When such depressions occur, slurry and polishing debris tend to accumulate there, potentially causing scratches and degrading the surface quality of the workpiece. Furthermore, if the window portion is less worn, it is more likely to remain than the polishing layer as polishing progresses, potentially resulting in the window portion becoming convex. Such convex window portions also tend to cause scratches and degrade the surface quality of the workpiece.

[0009] The present invention has been made in view of the above problems, and has as its object to provide a polishing pad that exhibits excellent flatness during slicing and dressing, and a method for manufacturing a polished product using the same. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by ensuring that the endpoint detection window and the polishing layer have a specific relationship in pulsed NMR analysis, thereby completing the present invention.

[0011] That is, the present invention is as follows. [1] a polishing layer and an end point detection window provided in an opening in the polishing layer; When the free induction decay curve of the spin-spin relaxation of 1H obtained by measuring it using pulsed NMR with the solid echo method was separated into three curves derived from the three components of the crystalline phase, mesophase, and amorphous phase in order of shortest relaxation time, The ratio (Lp20 / Lw20) of the amorphous phase abundance ratio Lw20 in the endpoint detection window to the amorphous phase abundance ratio Lp20 in the polishing layer at 20°C is 0.8~1.2 and The ratio (Sp80 / Sw80) of the abundance ratio Sw80 of the crystalline phase in the endpoint detection window to the abundance ratio Sp80 of the crystalline phase in the polishing layer at 80°C is 1.0~1.3 That is, Polishing pad. [2] the ratio (Mp20 / Mw20) of the abundance ratio Mw20 of the mesophase in the endpoint detection window to the abundance ratio Mp20 of the mesophase in the polishing layer at 20°C is 0.7 to 1.5; The polishing pad according to [1]. [3] the ratio (Mp80 / Mw80) of the abundance ratio Mw80 of the mesophase in the endpoint detection window to the abundance ratio Mp80 of the mesophase in the polishing layer at 80°C is 0.5 to 1.5; The polishing pad according to [1] or [2]. [4] The difference (|Lp20-Lw20|) between the abundance ratio Lw20 and the abundance ratio Lp20 is 10 or less. The polishing pad according to any one of [1] to [3]. [5] The abundance ratio Sw80 and the abundance ratio Sp The difference in 80 (|Sp80-Sw80|) is 15 or less. The polishing pad according to any one of [1] to [4]. [6] the endpoint detection window comprises a polyurethane resin WI; The polyurethane resin WI contains a structural unit derived from an aliphatic isocyanate. The polishing pad according to any one of [1] to [5]. [7] The polishing layer contains a polyurethane resin P, The polyurethane resin P contains a structural unit derived from an aromatic isocyanate. The polishing pad according to any one of [1] to [6]. [8] The polishing layer contains hollow fine particles dispersed therein. The polishing pad according to any one of [1] to [7]. [9] In the presence of a polishing slurry, using the polishing pad according to any one of [1] to [8], a polishing step of polishing an object to be polished to obtain a polished product; an end point detection step of detecting an end point by an optical end point detection method during the polishing. A method for manufacturing polished workpieces. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a polishing pad that exhibits excellent flatness during slicing and dressing, and a method for producing a polished product using the same. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic perspective view of a polishing pad according to an embodiment of the present invention. [Figure 2] 3 is a schematic cross-sectional view of an end point detection window portion of the polishing pad of the present embodiment. FIG. [Figure 3] 10 is a schematic cross-sectional view of another aspect of the end point detection window portion of the polishing pad of the present embodiment. FIG. [Figure 4] FIG. 1 is a schematic diagram showing a film thickness control system installed in CMP. [Figure 5A] FIG. 2 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 1 after slicing and before dressing. [Figure 5B]FIG. 2 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 1 after slicing and before dressing. [Figure 5C] FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 1 after slicing and before dressing. [Figure 6A] FIG. 2 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 1 after dressing. [Figure 6B] FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Example 2 after dressing. [Figure 6C] FIG. 10 is a diagram showing the surface state of the end point detection window portion of the polishing pad of Comparative Example 1 after dressing. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0015] 1. Polishing pad The polishing pad of this embodiment has a polishing layer and an end point detection window provided in an opening of the polishing layer, and when the free induction decay curve of the spin-spin relaxation of 1H obtained by measuring it using pulse NMR with the Solid Echo method is waveform-separated into three curves derived from the three components of the crystalline phase, mesophase, and amorphous phase in order of decreasing relaxation time, the ratio (Lp20 / Lw20) of the abundance ratio Lw20 of the amorphous phase in the end point detection window to the abundance ratio Lp20 of the amorphous phase in the polishing layer at 20°C is 0.5 to 2.0, and the ratio (Sp80 / Sw80) of the abundance ratio Sw80 of the crystalline phase in the end point detection window to the abundance ratio Sp80 of the crystalline phase in the polishing layer at 80°C is 0.5 to 2.0.

[0016] This improves flatness in the slicing process by preventing protrusions from forming, and improves flatness in the dressing process by preventing the end-point detection window from being over-polished relative to the polishing layer. In this embodiment, these two types of flatness are collectively referred to simply as "flatness."

[0017] A schematic perspective view of a polishing pad of this embodiment is shown in Figure 1. As shown in Figure 1, a polishing pad 10 of this embodiment has a polishing layer 11 which is a polyurethane sheet, an end-point detection window 12, and may optionally have a cushion layer 13 on the side opposite to the polishing surface 11a.

[0018] 2 and 3 show cross-sectional views of the periphery of the endpoint detection window 12 in FIG. 1. As shown in FIGS. 2 and 3, an adhesive layer 14 may be provided between the polishing layer 11 and the cushion layer 13, and an adhesive layer 15 may be provided on the surface of the cushion layer 13 for bonding to the table 22 in FIG. 4. The polishing surface 11a of the polishing pad of this embodiment may be flat as shown in FIG. 2, or may be uneven with grooves 16 formed therein as shown in FIG. 3. The grooves 16 may be formed by using a plurality of grooves of various shapes, such as concentric circles, a lattice pattern, or a radial pattern, either alone or in combination.

[0019] 1.1.End point detection window The end point detection window is a transparent member provided in an opening in the polyurethane sheet, and serves as a transmission path for light from the film thickness detection sensor in optical end point detection. In this embodiment, the end point detection window is circular, but it may be square, rectangular, polygonal, elliptical, or other shapes as needed.

[0020] In this embodiment, parameters related to the pulse NMR of the endpoint detection window and the polishing layer are specified in order to prevent the endpoint detection window from becoming recessed or cracked compared to the polishing layer when slicing is performed during the process of manufacturing the polishing pad, and to prevent the endpoint detection window from becoming recessed or protruding compared to the polishing layer when a dressing process is performed, thereby improving flatness.

[0021] Pulsed NMR Pulsed NMR is a type of solid-state NMR that detects the response signal to a pulse and measures the 1 This is a method for determining the H nuclear magnetic relaxation time (an index of molecular mobility). In response to the pulse, a free induction decay (FID) signal is obtained.

[0022] Pulse NMR is an analytical method for evaluating the mobility of polymer molecular chains as a whole system. Mobility can be evaluated by measuring the relaxation time of a resin composition and the signal intensity at that time. Generally, the lower the mobility of the polymer chain, the shorter the relaxation time, so the signal intensity decays faster, and the relative signal intensity, when the initial signal intensity is taken as 100%, decreases over a short period of time. Furthermore, the higher the mobility of the polymer chain, the longer the relaxation time, so the signal intensity decays slower, and the relative signal intensity, when the initial signal intensity is taken as 100%, decreases gradually over a long period of time.

[0023] For example, when measuring a resin, the FID obtained is the sum of the FIDs of multiple components with different relaxation times, and by separating this using the least squares method, the relaxation times of each component can be detected. Approximating the free induction decay curve at a given temperature obtained by measurement using the solid echo method of pulsed NMR into three components allows the signal obtained by the measurement to be classified as originating from the component with the lowest mobility (crystalline phase), the component with intermediate mobility (intermediate phase), or the component with the highest mobility (amorphous phase) in the sample, and the abundance ratio of these components can be determined.

[0024] Specifically, by fitting the free induction decay curve measured by the solid echo method of pulsed NMR using the following equation (1), it is possible to approximate it to three components: crystalline phase, intermediate phase, and amorphous phase, and the proportions of each component can be obtained by approximating it to these three components. M(t)=αexp(-(1 / 2)(t / T α ) 2)sinbt / bt+βexp(-(1 / Wa)(t / T β ) Wa )+γexp(-t / T γ )...(Formula 1) α: Composition ratio of crystalline phase T α : relaxation time of the crystalline phase (unit: msec) β: Composition ratio of intermediate phase T β : Relaxation time of intermediate phase (unit: msec) γ: Amorphous phase composition ratio T γ : Relaxation time of amorphous phase (unit: msec) t: Observation time (unit: msec) Wa: Shape factor b: shape factor

[0025] The results of such pulsed NMR measurements enable evaluation of the motility of the polishing layer and the endpoint detection window. In this embodiment, pulsed NMR is used to evaluate whether the motility of the polishing layer and the endpoint detection window is similar at a temperature of 20°C, which corresponds to the dressing temperature, and at a temperature of 80°C, which corresponds to the slicing temperature.

[0026] Specifically, the ratio (Lp20 / Lw20) of the amorphous phase content ratio Lw20 of the endpoint detection window to the amorphous phase content ratio Lp20 of the polishing layer at 20°C is 0.5 to 2.0, preferably 0.6 to 1.7, more preferably 0.7 to 1.5, and even more preferably 0.8 to 1.2. By ensuring that the ratio (Lp20 / Lw20) is within the above range, the mobilities of the materials constituting the polishing layer and the endpoint detection window are similar during dressing. This allows the polishing layer and the endpoint detection window to be uniformly treated during the dressing process, further improving the flatness after the dressing process.

[0027] Furthermore, the ratio (Sp80 / Sw80) of the abundance ratio Sw80 of the crystalline phase in the endpoint detection window to the abundance ratio Sp80 of the crystalline phase in the polishing layer at 80°C is 0.5 to 2.0, preferably 0.6 to 1.7, more preferably 0.9 to 1.5, and even more preferably 1.0 to 1.3. By having the ratio (Sp80 / Sw80) within the above range, the mobilities of the materials constituting the polishing layer and the endpoint detection window are similar during slicing. Therefore, the polishing layer and the endpoint detection window can be processed uniformly during the slicing process, further improving the flatness after the slicing process.

[0028] The ratio (Mp20 / Mw20) of the mesophase abundance ratio Mw20 in the endpoint detection window to the mesophase abundance ratio Mp20 in the polishing layer at 20°C is preferably 0.7 to 1.5, more preferably 0.7 to 1.3, and even more preferably 0.7 to 1.1. When the ratio (Mp20 / Mw20) is within the above range, the polishing layer and the endpoint detection window can be uniformly treated during the dressing treatment, and flatness after the dressing treatment tends to be further improved.

[0029] The ratio (Mp80 / Mw80) of the mesophase abundance ratio Mw80 in the endpoint detection window to the mesophase abundance ratio Mp80 in the polishing layer at 80°C is preferably 0.5 to 1.5, more preferably 0.7 to 1.4, and even more preferably 0.8 to 1.3. When the ratio (Mp80 / Mw80) is within the above range, the polishing layer and the endpoint detection window can be uniformly processed in the slicing process, and the flatness after the slicing process tends to be further improved.

[0030] The difference (|Lp20-Lw20|) between the abundance ratio Lw20 and the abundance ratio Lp20 is preferably 10 or less, more preferably 0 to 8.0, and even more preferably 0 to 5.0. When the difference (|Lp20-Lw20|) is within the above range, the polishing layer and the endpoint detection window can be uniformly treated in the dressing treatment, and flatness after the dressing treatment tends to be further improved.

[0031] Abundance ratio Sw80 and abundance ratio SpThe difference (|Sp80-Sw80|) between Sp80 and Sw80 is preferably 15 or less, more preferably 0 to 12, and even more preferably 0 to 8.0. When the difference (|Sp80-Sw80|) is within the above range, the polishing layer and the endpoint detection window can be uniformly processed in the slicing process, and the flatness after the slicing process tends to be further improved.

[0032] The abundance ratio Sw20 of the crystalline phase in the endpoint detection window at 20° C. is preferably 30 to 65%, more preferably 35 to 60%, and even more preferably 40 to 55%.

[0033] The abundance ratio Mw20 of the mesophase in the endpoint detection window at 20° C. is preferably 15 to 45%, more preferably 20 to 40%, and even more preferably 25 to 35%.

[0034] The abundance ratio Lw20 of the amorphous phase in the endpoint detection window at 20° C. is preferably 10 to 40%, more preferably 15 to 35%, and even more preferably 20 to 30%.

[0035] When the abundance ratio Sw20, abundance ratio Mw20, and abundance ratio Lw20 of the endpoint detection window at 20°C are each within the above ranges, the polishing layer and the endpoint detection window can be uniformly treated during the dressing process, and the flatness after the dressing process tends to be further improved. The sum of the abundance ratio Sw20, abundance ratio Mw20, and abundance ratio Lw20 is 100%.

[0036] The abundance ratio Sw80 of the crystalline phase in the endpoint detection window at 80° C. is preferably 15 to 50%, more preferably 20 to 45%, and even more preferably 25 to 40%.

[0037] The abundance ratio Mw80 of the mesophase in the endpoint detection window at 80° C. is preferably 10 to 35%, more preferably 15 to 30%, and even more preferably 20 to 25%.

[0038] The abundance ratio Lw80 of the amorphous phase in the endpoint detection window at 80° C. is preferably 30 to 60%, more preferably 35 to 55%, and even more preferably 40 to 50%.

[0039] When the abundance ratio Sw80, abundance ratio Mw80, and abundance ratio Lw80 of the endpoint detection window at 80°C are each within the above ranges, the polishing layer and the endpoint detection window can be processed uniformly during the slicing process, and the flatness after the slicing process tends to be further improved. The sum of the abundance ratio Sw80, abundance ratio Mw80, and abundance ratio Lw80 is 100%.

[0040] The measurement conditions for pulsed NMR are not particularly limited, but measurements can be performed under the conditions described in the Examples.

[0041] 1.1.3.Constituent Materials The material for the endpoint detection window is not particularly limited as long as it is a transparent member that can function as a window, but examples include polyurethane resin WI, polyvinyl chloride resin, polyvinylidene fluoride resin, polyethersulfone resin, polystyrene resin, polyethylene resin, and polytetrafluoroethylene resin. Among these, polyurethane resin WI is preferred. By using such a resin, the pulse NMR characteristics and transparency can be more easily adjusted, and flatness can be further improved.

[0042] The polyurethane resin WI can be synthesized from a polyisocyanate and a polyol, and contains structural units derived from the polyisocyanate and structural units derived from the polyol.

[0043] 1.1.3.1. Polyisocyanate-derived building blocks The polyisocyanate-derived structural unit is not particularly limited, but examples thereof include structural units derived from alicyclic isocyanates, structural units derived from aliphatic isocyanates, and structural units derived from aromatic isocyanates. Among these, the polyurethane resin WI preferably contains structural units derived from alicyclic isocyanates and / or aliphatic isocyanates, and more preferably contains structural units derived from aliphatic isocyanates. This makes it easier to adjust the pulse NMR values ​​within the above ranges, further improving transparency and further improving flatness during dressing and slicing.

[0044] The alicyclic isocyanate is not particularly limited, but examples thereof include 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, and isophorone diisocyanate.

[0045] The aliphatic isocyanate is not particularly limited, but examples thereof include hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), tetramethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, trimethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0046] The aromatic isocyanate is not particularly limited, but examples thereof include phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), xylylene diisocyanate, naphthalene diisocyanate, and diphenylmethane-4,4'-diisocyanate (MDI).

[0047] 1.1.3.2. Polyol-derived building blocks The structural unit derived from polyol is not particularly limited, but examples thereof include low molecular weight polyols having a molecular weight of less than 300 and high molecular weight polyols having a molecular weight of 300 or more.

[0048] The low molecular weight polyol is not particularly limited, but examples thereof include low molecular weight polyols having two hydroxyl groups such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexane glycol, 2,5-hexanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, tricyclodecane dimethanol, and 1,4-cyclohexane dimethanol; and low molecular weight polyols having three or more hydroxyl groups such as glycerin, hexanetriol, trimethylolpropane, isocyanuric acid, and erythritol. The low molecular weight polyols may be used alone or in combination of two or more.

[0049] Among these, a low molecular weight polyol having three or more hydroxyl groups is preferred, and glycerin is more preferred. By using such a low molecular weight polyol, it is easy to adjust the pulse NMR characteristics within the above range, the amount of wear can be adjusted, the flatness can be further improved, the transparency can be further improved, and the yellowing resistance of the window tends to be further improved.

[0050] The content of the structural units derived from a low-molecular-weight polyol having three or more hydroxyl groups is preferably 8.0 to 30 parts by mass, more preferably 10 to 25 parts by mass, and even more preferably 12.5 to 20 parts by mass, relative to 100 parts by mass of the structural units derived from a polyisocyanate. When the content of the structural units derived from a low-molecular-weight polyol having three or more hydroxyl groups is within the above range, the pulse NMR characteristics can be easily adjusted to fall within the above range, flatness can be further improved, transparency can be further improved, and the yellowing resistance of the window tends to be further improved.

[0051] The polymer polyol is not particularly limited, but examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, polyether polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. The polymer polyols may be used alone or in combination of two or more.

[0052] The number average molecular weight of the polymer polyol is preferably 300 to 3000, more preferably 500 to 2500. By using such a polymer polyol, it tends to be easier to adjust the pulse NMR characteristics to within the above range.

[0053] Among these, polyether polyols are preferred, and poly(oxytetramethylene) glycol is more preferred. By using such polymer polyols, it is easy to adjust the pulse NMR characteristics within the above range. In addition, flatness can be further improved, transparency can be further improved, and the yellowing resistance of the window tends to be further improved.

[0054] The content of the structural units derived from polyether polyol is preferably 60 to 130 parts by mass, preferably 65 to 120 parts by mass, and more preferably 70 to 110 parts by mass, relative to 100 parts by mass of the structural units derived from polyisocyanate. When the content of the structural units derived from polyether polyol is within the above range, it is easy to adjust the pulse NMR characteristics to within the above range, flatness can be further improved, transparency is further improved, and the yellowing resistance of the window tends to be further improved.

[0055] Furthermore, as the polyol, it is preferable to use a low molecular weight polyol in combination with a high molecular weight polyol, and it is more preferable to use a low molecular weight polyol having three or more hydroxyl groups in combination with a polyether polyol. This makes it easier to adjust the pulse NMR characteristics within the above range. In addition, it is possible to further improve flatness, transparency, and the yellowing resistance of the window tends to be further improved.

[0056] From the above viewpoints, the content of polyether polyol is preferably 2.0 to 15.0 parts, more preferably 3.0 to 12.5 parts, and even more preferably 4.0 to 9.0 parts per part of low-molecular-weight polyol having three or more hydroxyl groups.

[0057] 1.2. Polishing layer The polishing layer of this embodiment has an opening in which an end-point detection window is embedded. The position of the opening is not particularly limited, but it is preferable to provide it at a radial position corresponding to the film thickness detection sensor 23 installed on the table 22. The number of openings is also not particularly limited, but it is preferable to provide multiple openings at similar radial positions so that the window passes over the film thickness detection sensor 23 multiple times during one rotation of the polishing pad 10 attached to the table 22.

[0058] The form of the polishing layer is not particularly limited, but examples thereof include foamed resin molded bodies, non-foamed resin molded bodies, and resin-impregnated substrates in which a fibrous substrate is impregnated with a resin.

[0059] Here, the term "molded foam of resin" refers to a foam made of a specific resin without a fibrous base material. The foam shape is not particularly limited, but examples include spherical cells, nearly spherical cells, teardrop-shaped cells, and open cells in which the individual cells are partially connected.

[0060] Furthermore, the term "non-foamed resin molded article" refers to a non-foamed article made of a specific resin and not having a fibrous substrate. The term "non-foamed article" refers to an article that does not have the bubbles described above. In the first embodiment, the term "non-foamed resin molded article" also refers to an article in which a curable composition is applied to a substrate such as a film and cured. More specifically, the term "non-foamed resin molded article" also refers to a cured resin product formed by a labyrinth coater method, a small-diameter gravure coater method, a reverse roll coater method, a transfer roll coater method, a kiss coater method, a die coater method, a screen printing method, a spray coating method, or the like.

[0061] Furthermore, the resin-impregnated substrate refers to a substrate obtained by impregnating a fibrous substrate with a resin. The fibrous substrate is not particularly limited, but examples thereof include woven fabric, nonwoven fabric, and knitted fabric.

[0062] Pulsed NMR The abundance ratio Sp20 of the crystalline phase in the polishing layer is preferably 40 to 65%, more preferably 45 to 60%, and even more preferably 50 to 55%.

[0063] The abundance ratio Mp20 of the intermediate phase in the polishing layer is preferably 10 to 40%, more preferably 15 to 35%, and even more preferably 20 to 30%.

[0064] The amorphous phase content Lp20 of the polishing layer is preferably 10 to 35%, more preferably 15 to 30%, and even more preferably 20 to 25%.

[0065] When the abundance ratios Sp20, Mp20, and Lp20 of the endpoint detection window at 20°C are each within the above ranges, the polishing layer and the endpoint detection window can be uniformly treated during the dressing process, and the flatness after the dressing process tends to be further improved. The sum of the abundance ratios Sp20, Mp20, and Lp20 is 100%.

[0066] The abundance ratio Sp80 of the crystalline phase in the polishing layer is preferably 25 to 50%, more preferably 30 to 45%, and even more preferably 35 to 40%.

[0067] The abundance ratio Mp80 of the intermediate phase in the abrasive layer is preferably 10 to 40%, more preferably 15 to 35%, and even more preferably 20 to 30%.

[0068] The amorphous phase content Lp80 of the polishing layer is preferably 25 to 50%, more preferably 30 to 45%, and even more preferably 35 to 40%.

[0069] When the abundance ratios Sp80, Mp80, and Lp80 of the endpoint detection window at 80°C are each within the above ranges, the polishing layer and the endpoint detection window can be uniformly processed in the slicing process, and the flatness after the slicing process tends to be further improved. The sum of the abundance ratios Sp80, Mp80, and Lp80 is 100%.

[0070] The measurement conditions for pulsed NMR are not particularly limited, but measurements can be performed under the conditions described in the Examples.

[0071] 1.2.2.Polyurethane sheet In the following, a polyurethane sheet will be exemplified as an example of the polishing layer. The polyurethane resin P constituting the polyurethane sheet is not particularly limited, but examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more.

[0072] Such polyurethane resin P can be synthesized from a polyisocyanate and a polyol, and a reaction product of a urethane prepolymer and a curing agent is particularly preferred. Here, the urethane prepolymer can be synthesized from a polyisocyanate and a polyol. The polyisocyanate, polyol, and curing agent that constitute the polyurethane resin P will be described below.

[0073] 1.2.2.1. Polyisocyanate-derived building blocks The polyisocyanate-derived structural unit is not particularly limited, and examples thereof include a structural unit derived from an alicyclic isocyanate, a structural unit derived from an aliphatic isocyanate, and a structural unit derived from an aromatic isocyanate. Among these, aromatic isocyanates are preferred, and 2,4-tolylene diisocyanate (2,4-TDI) is more preferred.

[0074] Examples of the alicyclic isocyanate, aliphatic isocyanate, and aromatic isocyanate include those exemplified in the endpoint detection window.

[0075] 1.2.2.2. Polyol-derived building blocks The structural unit derived from a polyol is not particularly limited, and examples thereof include low-molecular-weight polyols having a molecular weight of less than 300 and high-molecular-weight polyols having a molecular weight of at least 300. Among these, it is preferable to use at least a low-molecular-weight polyol, and it is also preferable to use a low-molecular-weight polyol and a high-molecular-weight polyol in combination.

[0076] Examples of low-molecular-weight polyols and high-molecular-weight polyols include those exemplified in the endpoint detection window. Among these, low-molecular-weight polyols are preferably low-molecular-weight polyols having two hydroxyl groups, and more preferably diethylene glycol. Furthermore, high-molecular-weight polyols are preferably polyether polyols, and more preferably poly(oxytetramethylene) glycol.

[0077] 1.2.2.3. Hardener The curing agent is not particularly limited, but examples thereof include polyamines and polyols. The curing agents may be used alone or in combination of two or more.

[0078] The polyamine is not particularly limited, but examples thereof include aliphatic polyamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; and aromatic polyamines such as 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, and 2,2-bis(3-amino-4-hydroxyphenyl)propane.

[0079] Among these, aromatic polyamines are preferred, and it is more preferred to use 3'-dichloro-4,4'-diaminodiphenylmethane (MOCA).

[0080] Examples of polyols include the same polyols as those exemplified in the endpoint detection window. Among these, polymer polyols are preferred, polyether polyols are more preferred, and polypropylene glycol is even more preferred.

[0081] 1.2.2.4.Hollow particles The polishing layer preferably contains hollow fine particles dispersed therein. Specifically, the polyurethane sheet is preferably a foamed polyurethane sheet containing a polyurethane resin P and hollow fine particles dispersed therein. Such a polyurethane sheet has closed cells derived from the hollow fine particles, and tends to have an easily adjustable pulse NMR characteristic within the above range.

[0082] The hollow microparticles may be commercially available or may be synthesized by a conventional method. The material of the outer shell of the hollow microparticles is not particularly limited, and examples thereof include polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, and vinyl chloride-ethylene copolymer.

[0083] The shape of the hollow microparticles is not particularly limited and may be, for example, spherical or nearly spherical. When the hollow microparticles are expandable balloons, they may be used in an unexpanded state or in an expanded state.

[0084] The average particle size of the hollow microparticles contained in the polyurethane sheet is preferably 5 to 200 μm, more preferably 5 to 80 μm, even more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. Having an average particle size within the above range tends to make it easier to adjust the pulse NMR characteristics within the above range. The average particle size can be measured using a laser diffraction particle size analyzer (e.g., Mastersizer 2000, manufactured by Spectris Co., Ltd.).

[0085] 1.3.Other The polishing pad of this embodiment may have a cushion layer on the side opposite the polishing surface of the polishing layer, or an adhesive layer between the polishing layer and the cushion layer or on the surface of the cushion layer opposite the polishing layer side (the surface attached to the polishing machine). In this case, the cushion layer and the adhesive layer have openings in the same locations as the end point detection windows of the polishing layer.

[0086] 2. Manufacturing method of polishing pad The method for manufacturing the polishing pad of this embodiment is not particularly limited, but may include, for example, the steps of filling a mold to which a window member that will serve as the endpoint detection window is fixed with a resin composition that constitutes the polishing layer and curing it to obtain a resin block in which the window member is embedded, and slicing the obtained resin block to obtain a polyurethane sheet having an endpoint detection window in its opening, and the polishing surface of the obtained polyurethane sheet may be dressed if necessary.

[0087] The temperature during slicing is preferably 70° C. to 100° C. The temperature during dressing is preferably 20° C. to 30° C. This tends to further improve flatness.

[0088] 3. Manufacturing method of polished workpiece The method for manufacturing a polished product of this embodiment includes a polishing step in which the polishing pad is used to polish a workpiece in the presence of a polishing slurry to obtain a polished product, and an end point detection step in which an optical end point detection method is used to detect the end point during the polishing.

[0089] 3.1. Polishing process The polishing process may be primary lapping (rough lapping), secondary lapping (finish lapping), primary polishing (rough polishing), secondary polishing (finish polishing), or a combination of these. Here, "lapping" refers to polishing at a relatively high rate using coarse abrasive grains, and "polishing" refers to polishing at a relatively low rate using fine abrasive grains to improve surface quality.

[0090] Among these, the polishing pad of this embodiment is preferably used for chemical mechanical polishing (CMP). Hereinafter, the method for manufacturing the polished product of this embodiment will be described using chemical mechanical polishing as an example, but the method for manufacturing the polished product of this embodiment is not limited to the following.

[0091] The object to be polished is not particularly limited, but examples thereof include materials such as semiconductor devices and electronic components, particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), SiC (silicon carbide) substrates, GaAs (gallium arsenide) substrates, glass, substrates for hard disks and LCDs (liquid crystal displays), etc. In particular, semiconductor devices having metal wiring such as W (tungsten) and Cu (copper) are included.

[0092] The polishing method may be any conventionally known method and is not particularly limited. For example, first, a workpiece held on a holding platen arranged opposite the polishing pad is pressed against the polishing surface, and the polishing pad and / or holding platen are rotated while supplying slurry from the outside. The polishing pad and holding platen may rotate in the same direction at different rotation speeds, or in different directions. Furthermore, the workpiece may be polished while moving (rotating) inside the frame during the polishing process.

[0093] The slurry may contain water, chemical components such as an oxidizing agent such as hydrogen peroxide, additives, abrasive grains (abrasive particles; for example, SiC, SiO2, Al2O3, CeO2), etc. depending on the object to be polished and the polishing conditions.

[0094] 3.2.End-point detection process The method for manufacturing a polished product according to this embodiment includes an end point detection step in which the polishing step is performed by an optical end point detection method. Specifically, a conventionally known method can be used as the end point detection method by the optical end point detection method.

[0095] Figure 4 shows a schematic diagram of an optical endpoint detection method. This diagram illustrates a chemical mechanical polishing process in which a wafer W held by a top ring 21 is pressed against a polishing pad 10 attached to a table 22 while a slurry 24 is flowing thereon, thereby polishing and flattening the uneven film on the surface of the wafer W. The polishing apparatus 20 is equipped with a film thickness detection sensor 23 on the table 22 that monitors the film thickness in order to accurately complete the process by detecting a predetermined film thickness at the same time as planarization. The film thickness detection sensor 23 can detect the polishing endpoint by, for example, irradiating the polishing surface of the wafer W with light and measuring and analyzing the spectral intensity characteristics of the reflected light.

[0096] More specifically, the film thickness detection sensor 23 can detect changes in film thickness by irradiating light onto the surface of the wafer W through the end point detection window 12 and detecting the strength of the reflection intensity that arises from the phase difference between the light reflected by the film on the wafer W (wafer surface) and the light reflected at the interface between the film on the wafer W and the wafer substrate. [Example]

[0097] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples. Note that "parts" refers to parts by mass.

[0098] [Production Example 1: End Point Detection Window 1] A transparent member to become the endpoint detection window 4 was obtained by reacting 100 parts of 4,4'methylenebis(cyclohexyl isocyanate), 90.6 parts of poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 16.7 parts of glycerin.

[0099] [Production Example 2: End Point Detection Window 2] A transparent member to become the endpoint detection window 2 was obtained by reacting 100 parts of 4,4'methylenebis(cyclohexyl isocyanate), 103.6 parts of poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, and 15.9 parts of glycerin.

[0100] [Production Example 3: End Point Detection Window 3] A transparent member that would become the endpoint detection window 3 was obtained by reacting 100 parts of 4,4'methylenebis(cyclohexyl isocyanate), 78.6 parts of poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, 4.5 parts of glycerin, and 10.5 parts of ethylene glycol.

[0101] Example 1 A urethane prepolymer mixture was prepared by reacting 100 parts of a urethane prepolymer with an NCO equivalent of 420, which was prepared by reacting 2,4-tolylene diisocyanate (2,4-TDI), poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 650, poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 1000, and diethylene glycol (DEG). 2.9 parts of unexpanded hollow microparticles (average particle size: 8.5 μm) with an acrylonitrile-vinylidene chloride copolymer shell were added and mixed to obtain a urethane prepolymer mixture. The resulting urethane prepolymer mixture was placed in a first liquid tank and maintained at 60°C. Separately from the first liquid tank, 28.0 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (MOCA) was placed in a second liquid tank as a curing agent, where the mixture was heated to 120°C, melted, mixed, and then degassed under reduced pressure to obtain a curing agent melt.

[0102] Next, the liquids in the first liquid tank and the second liquid tank were poured into a mixer having two injection ports, respectively, and mixed by stirring to obtain a mixed liquid.

[0103] The resulting mixture was then poured into a mold in which the endpoint detection window 1 obtained as described above had been previously installed, and subjected to primary curing at 80°C for 30 minutes. The resulting block-shaped molded product was removed from the mold and subjected to secondary curing in an oven at 120°C for 4 hours, yielding a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C.

[0104] The sheet was then heated again in an oven at 120°C for 5 hours, after which it was sliced ​​and the sliced ​​surfaces were ground (buffed) as necessary to obtain a foamed polyurethane sheet. Double-sided tape was attached to the back of the resulting polyurethane sheet, a cushion layer was attached, and further double-sided tape was attached to the surface of the cushion layer to obtain a polishing pad.

[0105] When evaluating the cross section around the end point detection window after the dressing treatment, the polishing pad obtained as described above was dressed under the following conditions. (Dress conditions) Polishing machine used: Speedfam, product name "FAM-12BS" Platen rotation speed (polishing pad rotation speed): 50 rpm Flow rate: 100 ml / min (pure water at 20°C was dripped from the center of rotation of the polishing pad.) Dresser: 3M diamond dresser, model number "A188" Dresser rotation speed: 100 rpm Dressing pressure: 0.115kg / cm2 Dresser rotation direction: Rotates in the same direction as the polishing pad Exam time: 60 minutes

[0106] Example 2 A polishing pad was obtained in the same manner as in Example 1, except that the endpoint detection window 2 of Production Example 3 was used.

[0107] Comparative Example 1 A polishing pad was obtained in the same manner as in Example 1, except that the end point detection window 3 of Production Example 3 was used.

[0108] [Pulsed NMR] Equipment: Minispec MQ20 ​​(Bruker Biospin) Nuclide: 1 H Measurement: T2 Measurement method: Solid echo method Accumulation count: 256 times Repeat time: 1.0 sec Measurement temperature: 20°C, 80°C (measurement started 60 minutes after the device temperature reached the measurement temperature and the sample was set) Using the above-mentioned apparatus and conditions, ten sample pellets each measuring 8 mm in diameter and weighing approximately 50 mg were prepared and packed into a sample tube, and pulse NMR measurements were performed to obtain an attenuation curve. The obtained decay curve was fitted and analyzed using the above equation (1) to obtain the relaxation times of the crystalline phase, mesophase, and amorphous phase in the polyurethane resin. The fitting and analysis were performed using the software attached to the measurement device.

[0109] [Cross-sectional evaluation] For each pad obtained as described above, the area around the end point detection window after slicing but before dressing (the area surrounded by dashed line S in Figure 2) (Evaluation 1) and a cross section of the area around the end point detection window after dressing (the area surrounded by dashed line S in Figure 2) (Evaluation 2) were observed using a laser microscope (VK-X1000, manufactured by KEYENCE Corporation) in the connected mode at a magnification of 200 times within an area of ​​approximately 14 mm x 1 mm relative to the surface of the diameter of the end point detection window, and profile measurements of height information were performed based on the obtained laser images.

[0110] The results are shown in Figures 5A to 5C and Figures 6A to 6C. Figures 5A to 5C and Figures 6A to 6C show the cross-sectional measurement results of two end point detection windows, in which cross-sectional measurements were performed in the slice direction and in a direction perpendicular to the slice direction for each end point detection window.

[0111] In evaluation 1, if the endpoint detection window was within ±50 μm from the polished surface, it was marked as ○, and otherwise it was marked as ×. In evaluation 2, if the cross-sectional image was flat (the height was the same from the edge to the center), it was marked as ○, and if it was convex (the height increased from the edge to the center), it was marked as ×.

[0112] [Table 1] [Industrial Applicability]

[0113] The polishing pad of the present invention has industrial applicability as a pad that is suitably used for polishing semiconductor wafers and the like. [Explanation of symbols]

[0114] 10... Polishing pad, 11... Polishing layer, 11a... Polishing surface, 12... End point detection window, 13... Cushion layer, 14, 15... Adhesive layer, 16... Groove, 20... Polishing device, 21... Top ring, 22... Table, 23... Film thickness detection sensor, 24... Slurry, W... Wafer

Claims

1. a polishing layer and an end point detection window provided in an opening in the polishing layer; When the free induction decay curve of the spin-spin relaxation of 1H obtained by measuring with the solid echo method using pulsed NMR was separated into three curves derived from the three components of the crystalline phase, mesophase, and amorphous phase in order of shortest relaxation time, the ratio (Lp20 / Lw20) of the amorphous phase abundance ratio Lw20 in the endpoint detection window to the amorphous phase abundance ratio Lp20 in the polishing layer at 20°C is 0.8 to 1.2; the ratio (Sp80 / Sw80) of the abundance ratio Sw80 of the crystalline phase in the endpoint detection window to the abundance ratio Sp80 of the crystalline phase in the polishing layer at 80°C is 1.0 to 1.3; Polishing pad.

2. the ratio (Mp20 / Mw20) of the abundance ratio Mw20 of the mesophase in the endpoint detection window to the abundance ratio Mp20 of the mesophase in the polishing layer at 20°C is 0.7 to 1.5; The polishing pad of claim 1 .

3. the ratio (Mp80 / Mw80) of the abundance ratio Mw80 of the mesophase in the endpoint detection window to the abundance ratio Mp80 of the mesophase in the polishing layer at 80°C is 0.5 to 1.5; The polishing pad according to claim 1 or 2.

4. The difference between the abundance ratio Lw20 and the abundance ratio Lp20 (|Lp20-Lw20|) is 10 or less; The polishing pad according to any one of claims 1 to 3.

5. The difference between the abundance ratio Sw80 and the abundance ratio Sp80 (|Sp80-Sw80|) is 15 or less, The polishing pad according to any one of claims 1 to 4.

6. the endpoint detection window contains a polyurethane resin WI, The polyurethane resin WI contains a structural unit derived from an aliphatic isocyanate. The polishing pad according to any one of claims 1 to 5.

7. The polishing layer contains a polyurethane resin P, The polyurethane resin P contains a structural unit derived from an aromatic isocyanate. The polishing pad according to any one of claims 1 to 6.

8. The polishing layer contains hollow fine particles dispersed therein. The polishing pad according to any one of claims 1 to 7.

9. a polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 8 in the presence of a polishing slurry to obtain a polished product; an end point detection step of detecting an end point by an optical end point detection method during the polishing. A method for manufacturing polished workpieces.

Images