CMP device and polishing temperature control method thereof

Abstract

The invention provides a polishing device and a polishing method capable of properly controlling the polishing temperature. A CMP apparatus (100) for polishing the surface of a workpiece by pressing the workpiece held by a rotatable polishing head (50) against a rotatable stage (110), the CMP apparatus (100) being characterized by being provided with: a mixer (200) which is adjacent to the stage and mixes a slurry and a liquid other than the slurry; and a temperature adjustment unit (300) that adjusts the temperature of the liquid.

Description

Technical Field

[0001] The present invention relates to a CMP device for polishing the surface of a semiconductor wafer and the like and a polishing temperature control method thereof. Background Art

[0002] Conventionally, it is known that in a polishing process using a chemical mechanical polishing (CMP) apparatus, a workpiece such as a semiconductor substrate wafer is polished using a polishing agent or a polishing liquid slurry. During a polishing process using a CMP apparatus, the polishing temperature, which corresponds to the temperature of the wafer, etc., being the polishing portion during the polishing process, may affect the polishing rate. Specifically, the polishing temperature difference from the center to the outer edge of the wafer may affect the distribution of the polished amount of the wafer. For example, in polishing substrates such as silicon and silicon carbide, or silicon oxide films, metal wiring films, etc., particularly in metal polishing, the polishing temperature may have a significant impact on the polishing rate. With the recent increase in wafer diameter, it may be necessary to further accurately control the polishing temperature.

[0003] Patent Documents 1-5 describe examples of polishing wafer surfaces using CMP apparatuses. For example, the CMP apparatus described in Patent Document 1 includes a platform for holding a polishing pad and a carrier capable of lateral movement across the polishing pad by an actuator to hold the substrate relative to the polishing surface of the polishing pad during the polishing process. The apparatus also includes a thermal control system and a controller. The thermal control system includes multiple heaters and coolers that independently control the temperatures of multiple zones on the polishing pad. The controller controls the thermal control system to generate a first zone on the polishing pad having a first temperature and a second zone having a second temperature different from the first temperature.

[0004] Patent Document 2 discloses a method for achieving a highly flat polished surface without leaving polishing scratches on the polished wafer. Specifically, the CMP apparatus comprises: a supply unit for supplying slurry to the surface of a polishing pad containing water-soluble particles; a holding unit for holding the polished object and bringing the object into contact with the polishing pad surface; a temperature setting unit disposed on the polishing pad surface to set the temperature of the polishing pad surface; and a control unit for controlling the operation of the supply unit, the holding unit, and the temperature setting unit. After performing a first polishing step in which the polishing pad surface temperature is set within a first temperature range, the control unit performs a second polishing step in which the polishing pad surface temperature is set within a second temperature range.

[0005] Patent Document 3 describes a slurry supply system that suppresses the coarsening of polishing particles caused by agglomeration of the slurry supplied to the CMP apparatus. The system comprises a sealed slurry bottle, a piping system, a wet nitrogen generator, wet nitrogen supply piping, a suction nozzle, a discharge nozzle, a temperature regulator, a flow control valve, a liquid feed pump, and a control system for controlling the operation and flow rate of each liquid feed pump. During the polishing process in the CMP apparatus, the liquid feed pump is operated intermittently, alternately running and stopping the pump at regular intervals. A stirring device such as a propeller disposed within the slurry bottle is not used; the slurry is stirred by spraying the slurry from the discharge nozzle.

[0006] In Patent Document 4, when polishing an object having Cu wiring formed using a damascene method, the following three steps are performed during polishing using a CMP apparatus to prevent residual Cu film from being polished during the CMP process. In the first step, the Cu film is polished using a non-abrasive slurry on a first polishing platen, stopping the polishing of the Cu film at the barrier metal layer. In the second step, the surface of the semiconductor wafer is polished using a slurry prepared by mixing the non-abrasive slurry and silica slurry immediately before polishing on a second polishing platen, removing any residual Cu film from the localized polishing in the first step. In the third step, the barrier metal layer outside the wiring trench is polished using silica slurry on the third polishing platen, forming Cu wiring within the wiring trench.

[0007] Patent Document 5 describes an attempt to suppress the temperature increase of the metal film surface caused by exothermic reactions in the metal system, which could lead to variations in the chemical reaction rate of the processed surface, during planarization polishing of the surface of a wafer having a metal wiring film using the CMP method. Therefore, the polishing apparatus is equipped with a temperature control mechanism that controls the temperature of air supplied from air outlets of a wafer carrier to a predetermined value. The wafer carrier comprises a backing plate having air outlets on its lower surface, which applies a pressing force to the wafer through a pressure air layer formed by the air supplied from the air outlets; and a protective sheet that contacts the wafer and transmits the pressing force applied from the backing plate through the pressure air layer to the wafer. Prior art literature Patent Literature

[0008] Patent Document 1: Japanese Patent Application No. 2022-529635 Patent Document 2: Japanese Patent Application Laid-Open No. 2012-178450 Patent Document 3: Japanese Patent Application Laid-Open No. 2000-158339 Patent Document 4: Japanese Patent Application Laid-Open No. 2003-115488 Patent Document 5: Japanese Patent Application Laid-Open No. 2006-237035 Summary of the Invention Problems to be solved by the invention

[0009] In the manufacture of semiconductor wafers, after forming a pattern or metal wiring layer on the wafer substrate surface, the substrate surface is polished to a flat surface. The next metal wiring layer or pattern is then formed on the polished surface, and the surface of the formed pattern is polished to a flat surface. By repeating this process, multiple wiring layers can be formed on the wafer substrate surface.

[0010] The CMP method is commonly used to polish the surface of wafer substrates. In CMP, a polishing pad is placed on a rotating platen called a platen, which is then rotated. The wafer is also rotated about its center, and polishing is performed using abrasive particles contained in the slurry. The quality of this polishing is affected by the frictional heat generated during polishing. In particular, the temperature of the polishing area rises, which can affect the flatness of the wafer surface and cause surface damage.

[0011] The wafer's circumferential velocity is highest at the wafer's outer periphery, while it approaches zero at the wafer's center. Consequently, due to the varying circumferential velocities of the wafer, the relative velocity between the polishing pad and the wafer varies depending on the position of the polishing pad. This relative velocity variation is believed to contribute to variations in heat generated during polishing. The larger the wafer diameter, the more significant this circumferential velocity difference becomes.

[0012] It should be noted that after the pattern or metal wiring layer is formed on the wafer substrate surface, the wafer is sometimes thinned by grinding. However, in this case, the substrate thickness varies within the grinding process tolerance. In thinned wafers, the thermal resistance varies due to the local thickness of the wafer and the metal wiring pattern formed, and the transfer and diffusion rate of polishing heat also change. This can lead to a deviation from the uniform polishing process that maintains a constant temperature in the polishing section.

[0013] Patent Document 1 discloses a method for polishing wafers using a CMP method, where a polishing pad is divided into multiple zones and each zone is temperature-controlled using a heater and a cooler. While this publication offers the advantage of arbitrarily controlling the polishing profile, it requires multiple heater and cooler controls to measure the polishing temperature and maintain the corresponding temperature in each part of the polishing pad, resulting in a larger device. Furthermore, most polishing pads in recent years are relatively thick, so the temperature adjusted on the platen is not necessarily transmitted to the wafer.

[0014] Patent Document 2 discloses a method for performing multiple polishing cycles by controlling the surface temperature of a polishing pad to a first temperature at which the elastic modulus of the polishing pad is high and the flatness of the surface of the object being polished is maintained, and a second temperature at which polishing damage caused by the polishing pad is minimized. The CMP method described in this publication achieves significant results under the same polishing conditions, but it does not take into account the difference in processing heat generated by the different circumferential speeds of the wafer at the periphery and center of the wafer.

[0015] It should be noted that, as described in Patent Document 3, when using a CMP method to polish a wafer through a slurry, the temperature of the polishing section can be controlled with greater precision by adjusting the slurry temperature. However, when the slurry is heated for an extended period of time, additives contained in the slurry may deteriorate and promote aggregation. If aggregation occurs within the slurry, it can adversely affect the temperature control of the polishing section achieved by controlling the slurry temperature, and may also cause damage to the wafer surface.

[0016] Furthermore, even when a Cu film on a semiconductor substrate is polished using a CMP method using multiple polishing plates as described in Patent Document 4, the circumferential speed varies depending on the polishing position of the semiconductor wafer. This can lead to differences in the processing heat generated between the platen and the wafer, and this difference in processing heat can affect wafer properties.

[0017] In the CMP method for polishing a wafer surface described in Patent Document 5, when polishing a metal wiring portion, air controlled to a predetermined temperature is blown toward the back side of the substrate in response to local changes in the wafer surface caused by the exothermic reaction of the metal. This method allows for strict temperature control of the polishing portion, but the structure becomes complex.

[0018] In addition to the above, the wafer temperature may be adjusted by adjusting the temperature of an air-floating polishing head with an air layer between the polishing head and the wafer. However, the air layer may make it difficult for the heat of the polishing head to be transferred to the wafer.

[0019] Furthermore, the temperature of the polishing section is sometimes controlled by adjusting the temperature of the slurry by adjusting the temperature of the pipe for supplying the slurry. However, the temperature of the slurry retained in the pipe portion being temperature-controlled may change unexpectedly.

[0020] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a polishing apparatus and a polishing method capable of appropriately controlling the polishing temperature. Means of solving problems

[0021] The first CMP device of the present invention is a CMP device that pushes a workpiece held by a rotatable polishing head against a freely rotatable platform to polish the surface of the workpiece, and is characterized in that the CMP device includes: a mixer, which is adjacent to the platform and mixes slurry and liquid other than slurry; and a temperature adjustment unit, which adjusts the temperature of the liquid.

[0022] The second CMP apparatus of the present invention is based on the first CMP apparatus, wherein the mixer includes a dropping unit for dropping a polishing liquid obtained by mixing the slurry and the liquid onto the platform, and the dropping unit is located upstream in the rotation direction of the platform.

[0023] The third CMP apparatus of the present invention is based on the second CMP apparatus, wherein the mixer is arranged on the platform.

[0024] A fourth CMP apparatus according to the present invention is based on the third CMP apparatus, and is characterized in that the liquid is pure water.

[0025] The first polishing temperature control method of the CMP device of the present invention is a polishing temperature control method of a CMP device, which pushes a workpiece held by a rotatable polishing head onto a rotatable platform to polish the surface of the workpiece. The polishing temperature control method is characterized in that the temperature of a liquid other than the slurry is adjusted, and the temperature of a polishing liquid formed by mixing the slurry and the liquid is adjusted in a mixer adjacent to the platform.

[0026] A second CMP apparatus polishing temperature control method of the present invention is based on the first CMP apparatus polishing temperature control method, characterized in that the polishing liquid is supplied upstream of the polishing head in the rotation direction of the platen. Effects of the Invention

[0027] The present invention provides a polishing device and a polishing method capable of properly controlling the polishing temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a perspective view of a CMP apparatus according to an embodiment. Figure 2 This is a schematic diagram showing an example of a CMP apparatus system according to an embodiment. Figure 3 It is a partial cross-sectional view schematically showing an example of a cage. Figure 4 It is a schematic diagram showing an example of a mixer according to the embodiment. Figure 5 This is a flowchart showing an example of a method for controlling the polishing temperature according to the embodiment. Figure 6 This is a schematic diagram showing an example of a mixer according to Modification 1. Figure 7 This is a schematic diagram showing an example of a CMP apparatus system according to Modification 2. Description of Reference Numerals 50: Polishing head; 52: Motor; 54: Rotating shaft; 56: Holder; 58: Head; 60: Pressure plate; 62: Retaining ring; 64: Top ring; 66: Spring; 68: Stop pin; 70: Compressed air passage; 100: CMP device; 110: Platform; 112: Motor; 114: Rotating shaft; 120: Polishing pad; 150: CMP device control unit; 200: Mixer (static mixer); 202: Housing; 204: Helical mixer blade; 210: Dropping unit (nozzle); 222: Inlet pipe mounting member; 224: Liquid (pure water); 226: Slurry inlet pipe mounting part; 228: slurry; 232: inlet pipe; 234, 236: slurry inlet pipe; 238: compressed air inlet pipe; 239: compressed air inlet part; 242, 244, 246, 248: valve; 252, 254, 256: pump; 262: liquid tank; 264, 266: slurry tank; 268: compressed air source; 270: temperature detector; 300: temperature regulating device (temperature regulating unit); 310: control device (of pure water temperature control device); 320: pump control device; 400: polishing liquid; 500: supply system; W: chip. DETAILED DESCRIPTION

[0029] Hereinafter, a CMP apparatus according to an embodiment will be described with reference to the drawings.

[0030] Figure 1 is a perspective view of a CMP apparatus 100 according to this embodiment. Figure 2 This is a schematic diagram showing an example of a CMP apparatus system according to this embodiment.

[0031] exist Figure 1 In the embodiment, the CMP apparatus 100 includes a polishing head 50 that holds a workpiece, such as a wafer W; a rotatable platform 110; a polishing pad 120 disposed on the platform 110; and a mixer 200. Furthermore, the CMP apparatus 100 has an air pressure introduction jig having an air pressure introduction portion 239 mounted near one side thereof.

[0032] CMP apparatus 100 uses Figure 2 The polishing liquid 400 shown, such as a slurry, polishes the wafer W. The CMP apparatus 100 is provided with a surrounding member around the platform 110 to collect the polishing liquid 400, such as a slurry, used during polishing between the polishing pad 120 on the upper surface of the platform 110 and the wafer W, preventing leakage to the outside. Hereinafter, "a slurry," "a liquid formed by mixing multiple slurries," or "a liquid, such as pure water or a liquid formed by mixing multiple slurries" may be simply referred to as "slurry" or "polishing liquid."

[0033] The polishing head 50 is disposed on the platform 110 and the polishing pad 120. The polishing head 50 is opposed to the polishing pad 120. The polishing head 50 is opposed to a portion of the polishing pad 120, for example.

[0034] The platform 110 is formed in a disk shape, for example. The diameter of the platform 110 is, for example, larger than the diameter of the polishing head 50 .

[0035] The polishing pad 120 is, for example, disc-shaped. It is attached to the platform 110 and mounted thereon. It is, for example, made of polyurethane. It is, for example, IC1000(TM) or IC1400(TM) manufactured by Nittany DuPont, and has an independent cell structure. Such a polishing pad 120 can, for example, evenly retain a slurry serving as a polishing liquid within the cells formed. While the IC1400 offers superior polishing properties for metal wiring films compared to the IC1000, it may be less able to evenly distribute and dissipate frictional heat.

[0036] The mixer 200 is arranged on the polishing pad 120 (or the platform 110) at a different circumferential position from the polishing head 50. Figure 1 In the example shown, the mixer 200 is arranged on the polishing pad 120 at a circumferential position on the opposite side of the polishing head 50. In other words, Figure 1 In the illustrated example, the mixer 200 is disposed above the platform 110 and upstream of the polishing head 50 in the direction of rotation of the platform 110. It should be noted that the mixer 200 may also be disposed on the polishing pad 120 near the polishing head 50. Furthermore, the mixer 200 may not be disposed on the polishing pad 120, as long as the pipe supplying the polishing liquid 400, such as a slurry, to the polishing pad 120 is not excessively long, or, for example, the temperature of the polishing liquid 400 mixed in the mixer 200 is substantially constant.

[0037] The mixer 200 is, for example, a static mixer. It should be noted that the mixer 200 may also be a mixer other than a static mixer. For example, the mixer 200 may be another type of static mixer or a dynamic mixer.

[0038] The mixer 200 includes a dropping unit (nozzle) 210, an introduction pipe 232, and a plurality of slurry introduction pipes 234 and 236. The mixer 200 may not include a plurality of slurry introduction pipes, but may only include at least one slurry introduction pipe.

[0039] The dripping unit 210 is provided on the lower surface near the top end of the mixer 200 and drips the polishing liquid, for example, slurry 400, discharged from the mixer 200 onto the polishing pad 120. Figure 1In the illustrated example, the dripping unit 210 is positioned above the polishing pad 120 (or the platform 110) and upstream of the polishing head 50 in the rotational direction of the platform 110. It should be noted that the dripping unit 210 may be positioned elsewhere as long as it is positioned above the polishing pad 120 (or the platform 110). For example, the dripping unit 210 may be positioned adjacent to the polishing head 50.

[0040] The introduction pipe 232 is installed at a portion of the mixer 200 substantially opposite to the portion where the dripping unit 210 is installed. Figure 1 In the illustrated example, the introduction pipe 232 is attached to the end surface of the mixer 200 on the opposite side to the portion where the dripping unit 210 is attached.

[0041] The slurry introduction pipes 234 and 236 are installed at a portion of the mixer 200 substantially opposite to the portion where the dripping unit 210 is installed. Figure 1 In the illustrated example, the slurry introduction pipes 234 and 236 are attached to the side surface of the end portion of the mixer 200 on the opposite side to the portion where the dropping unit 210 is attached.

[0042] Below, refer to Figure 2 The structure of the CMP apparatus 100 , the control system, and the supply system 500 will be described in more detail. exist Figure 2 In the illustrated example, the CMP apparatus 100 further includes a motor 112, a rotating shaft 114, a CMP apparatus controller 150, a compressed air inlet pipe 238, a valve 248, a compressed air source 268, a temperature detector 270, and the like. It should be noted that the valve 248 and the compressed air source 268 may also be provided independently of the CMP apparatus 100.

[0043] The supply system 500 includes a plurality of valves 242, 244, and 246, pumps 252, 254, and 256, a liquid tank 262, a plurality of slurry tanks 264 and 266, a temperature adjustment (temperature control) device 300, a controller 310 (of a pure water temperature control device), and a pump control device 320. The supply system 500 may be provided in the CMP apparatus 100 or independently of the CMP apparatus 100. Furthermore, a portion of the supply system 500 may be provided in the CMP apparatus 100. It should be noted that the supply system 500 may include only one slurry tank. In this case, the number of valves and pumps in the supply system 500 may also vary. It should be noted that the CMP apparatus 100 and the supply system 500 may sometimes be collectively referred to as a CMP apparatus system.

[0044] The CMP apparatus control unit 150 controls various components of the CMP apparatus 100. The CMP apparatus control unit 150 controls, for example, the rotation and stop of the motor 52 of the polishing head 50 and the motor 112 of the platen 110.

[0045] A rotation shaft 114 is provided at the base or underside of the platform 110. The rotation shaft 114 is, for example, coaxially connected to the platform 110. A motor 112 is provided at the base or underside of the rotation shaft 114. The motor 112 is, for example, coaxially connected to the rotation shaft 114. The motor 112 drives the platform 110 and the rotation shaft 114 to rotate about the central axis of the platform 110 and the rotation shaft 114.

[0046] Temperature detector 270 detects, for example, the temperature of polishing liquid 400. Temperature detector 270 detects (or measures) the temperature of polishing liquid 400 immediately before it is supplied to polishing pad 120 or platen 110. Temperature detector 270 is, for example, located on or near polishing pad 120, or mixer 200, or near mixer 200. It should be noted that temperature detector 270 may also be located in locations other than these. Temperature detector 270 is connected to control device 310. Temperature detector 270 outputs information on the detected temperature of polishing liquid 400 to control device 310.

[0047] Liquid tank 262 is connected to temperature control device 300 via valve 242 and pump 252. Liquid tank 262 stores liquid other than slurry, such as pure water. The liquid other than slurry stored in liquid tank 262 is used, for example, to adjust the temperature of the slurry. Liquid tank 262 supplies the stored liquid, such as pure water, to temperature control device 300.

[0048] Multiple slurry tanks 264 and 266 are connected to the mixer 200 via valves 244 and 246, pumps 254 and 256, and slurry inlet pipes 234 and 236, respectively. The multiple slurry tanks 264 and 266 each store slurry. The multiple slurry tanks 264 and 266 can store the same type of slurry or different types of slurry. The slurry tanks 264 and 266 supply the stored slurry to the mixer 200.

[0049] The temperature adjustment device 300 cools and / or heats a liquid such as pure water. The temperature adjustment device 300 includes a heater and / or a cooler. The temperature adjustment device 300 is connected to the inlet pipe 232. For example, when adjusting the temperature of pure water, the temperature adjustment device 300 can be adjusted within a range of 0°C to 70°C. It should be noted that the temperature adjustment device 300 can also adjust the temperature of pure water to a temperature outside the range of 0°C to 70°C.

[0050] The control device 310 controls the temperature control device 300. The control device 310 controls the temperature of the liquid, such as pure water, flowing through the temperature control device 300 based on the temperature detected by the temperature detector 270 disposed at or near the mixer 200 or the polishing pad 120.

[0051] The pump controller 320 controls the operations of the pumps 252 , 254 , and 256 . The pump controller 320 inputs outputs such as control information to the controller 310 of the temperature adjustment device 300 .

[0052] The compressed air source 268 is connected to the polishing head 50 via the compressed air introduction pipe 238 and the valve 248. The compressed air source 268 supplies compressed air such as factory air to the polishing head 50.

[0053] The polishing head 50 includes a motor 52, a rotating shaft 54, and a holder 56. The holder 56 holds a wafer W therein. The rotating shaft 54 ​​is provided on the upper side of the holder 56. The holder 56 is coaxially connected to the rotating shaft 54, for example.

[0054] A motor 52 is provided on the upper side or top of the rotating shaft 54. The rotating shaft 54 ​​is, for example, coaxially connected to the motor 52. The rotating shaft 54 ​​is arranged to be movable in the vertical direction. The rotating shaft 54 ​​controls the distance between the holder 56 mounted at the lower end of the rotating shaft 54 ​​and the polishing pad 120 by controlling the motor (not shown).

[0055] The motor 52 is driven to rotate the holder 56 (wafer W) and the rotation shaft 54 ​​around the central axis of the holder 56 (wafer W) and the rotation shaft 54 ​​.

[0056] Figure 3 It is a partial cross-sectional view schematically showing an example of the retainer 56 . The diameter of the lower end portion of the rotating shaft 54 ​​is larger than the diameter of the upper portion of the lower end portion. Figure 3 In the illustrated example, the lower end portion of the rotating shaft 54 ​​is formed in a disk shape.

[0057] The retainer 56 includes a head 58, a pressure plate 60, a retaining ring 62, a top ring 64, a spring 66, a stopper pin 68, and the like. The retainer 56 may include structures other than the head 58, the pressure plate 60, the retaining ring 62, the top ring 64, the spring 66, and the stopper pin 68, or may not include at least one of them.

[0058] The head 58 is attached to the lower end portion (or the disc-shaped portion) of the head rotation shaft 54. The diameter of the head 58 is larger than the diameter of the lower end portion of the rotation shaft 54, for example.

[0059] The top ring 64 is formed in an annular shape and is attached to the lower end portion of the rotating shaft 54. The top ring 64 has a fitting structure formed on the inner circumference side.

[0060] The retaining ring 62 is formed in an annular shape. The retaining ring 62 has engaging portions on the outer and inner sides. The engaging portion on the outer periphery of the retaining ring 62 engages with the engaging structure of the top ring 64. The retaining ring 62 holds the wafer W with the polished surface facing downward at the innermost periphery.

[0061] The pressure plate 60 engages with the mating portion on the inner circumference of the retaining ring 62. For example, the pressure plate 60 engages with the mating portion on the inner circumference of the retaining ring 62 with some clearance. The outer circumference of the pressure plate 60 has holes formed at multiple locations, and the stopper pins 68 can engage with these holes. The stopper pins 68 are wound around the springs 66.

[0062] A compressed air passage 70 is formed as a through hole at the center of the rotating shaft 54 ​​of the polishing head 50 and the center of the head 58. Figure 2 The illustrated compressed air source 268 supplies compressed air via the compressed air passage 70 to an air chamber, which is a space formed between the lower surface of the head 58 and the pressure plate 60 .

[0063] Below, refer to Figure 2 and Figure 3 , a method for polishing the wafer W is described. The polishing head 50 places a wafer W within the retaining ring 62 of the retainer 56 and drives a vacuum pump (not shown) to draw the wafer W toward the pressure plate 60. While holding the wafer W under suction, the polishing head 50 lowers its head 58 toward the polishing pad 120 (or the platform 110). When the head 58 is positioned at a predetermined height relative to the platform 110, the polishing head 50 stops lowering the head 58 and stops driving the vacuum pump. The polishing head 50 then places the wafer W on the polishing pad 120.

[0064] When the wafer W is placed on the polishing pad 120 , the platform 110 is rotated by the motor 112 , and the polishing liquid 400 is supplied to the polishing pad 120 from the dripping unit 210 attached to the mixer 200 . The mixer 200 is arranged upstream of the polishing head 50 in the rotation direction of the platform 110 .

[0065] When a wafer W is placed on the polishing pad 120, compressed air is supplied from a compressed air source 268, such as factory air, via a valve 248 and a compressed air inlet pipe 238 into the air chamber, a space formed between the lower surface of the head 58 and the pressure plate 60. When compressed air is supplied to the air chamber, the air chamber is filled with the compressed air. The pressure of the compressed air filling the air chamber presses the pressure plate 60 toward the polishing pad 120. Because the wafer W is positioned on the lower surface of the pressure plate 60, when the pressure plate 60 is pressed toward the polishing pad 120, the wafer W is also pressed by the pressure plate 60 and pressed against the polishing pad 120. While the polishing liquid 400 is directed to the interface between the wafer W and the polishing pad 120, the wafer W is polished.

[0066] It should be noted that when the wafer W is pressed against the polishing pad 120, the wafer W is rotated about the rotation axis 54 of the polishing head 50. When the head 58 rotates, its rotation is transmitted to the pressure plate 60 via the stopper pin 68. The rotation of the pressure plate 60 is transmitted to the wafer W pressed by the pressure plate 60, causing the wafer W to also rotate. As a result, the wafer W is pressed against the polishing pad 120 while rotating.

[0067] Figure 4 This is a schematic diagram showing an example of the mixer 200 according to the present embodiment. exist Figure 4 In the example shown, the mixer 200 has an inlet pipe mounting member 222 and a slurry inlet pipe mounting member 226. Figure 4 Although not shown in the figure, the mixer 200 has a plurality of slurry introduction pipe mounting members 226. It should be noted that the mixer 200 may also have only one slurry introduction pipe mounting member 226.

[0068] The inlet pipe mounting piece 222 is mounted on the flange at the left end (the flange of the liquid inlet portion). Figure 2 The introduction pipe 232 is shown. The introduction pipe fitting 222 is used to introduce the liquid, such as pure water 224, whose temperature has been adjusted by the temperature adjustment device 300, into the mixer 200 through a through hole formed in the center.

[0069] The flange of the liquid inlet portion is combined with the flange of at least one slurry introduction pipe mounting portion. For example, at least one slurry introduction pipe mounting member 226 is mounted on the branch portion flange in at least one direction that is perpendicular to the direction in which the liquid, such as pure water 224, flows. By mounting the slurry introduction pipe 234 (236) on the slurry introduction pipe mounting member 226, the adjusted slurry 228 can be introduced from the tank 264 (266) into the mixer 200. It should be noted that in Figure 4 In the example shown, for convenience of explanation, only one slurry input portion is used. However, another slurry input portion may be provided after the pure water input portion so as to overlap in the axial direction.

[0070] The mixer 200 mixes liquids such as pure water 224 and slurry 228 in the mixer portion through the action of each pump 252, 254, 256. The mixer portion is installed on the flow side of the pure water 224 and slurry 228, i.e., the downstream side, with the flange side of the liquid inlet portion and the flange side of at least one slurry inlet pipe installation portion as the upstream side. The mixer portion is composed of a cylindrical tube (shell) 202 having flanges at both ends and a spiral mixer blade 204 arranged in the shell. As the pure water 224 and slurry 228 flow down in the axial direction in the space formed by the spiral mixer blade 204, the slurry 228 is mixed in the pure water 224. The mixer 200 is installed at the downstream ( Figure 4 A dripping unit (nozzle) 210 mounted on the lower surface of the dripping portion (right end side in the center) drips or sprays the polishing liquid 400 onto the upper surface of the polishing pad 120 .

[0071] Here, the slurry 228 is appropriately selected depending on the polishing target. However, when polishing a wafer W with Cu wiring, etc., a slurry containing silica is preferably used. When polishing a surface that does not yet have a wiring layer, etc., a slurry containing alumina, polymer beads, etc. can be used. Alternatively, the slurry 228 may contain manganese abrasive grains or diamond abrasive grains. The silica, alumina, and polymer beads used as abrasive grains are, for example, fine-particle powders with an outer diameter of approximately 100 nm. It should be noted that the slurry 228 may contain abrasive grains other than those listed above, or may not contain abrasive grains at all.

[0072] Figure 5 This is a flowchart showing an example of a method for controlling the polishing temperature according to this embodiment. The CMP system sets a set operating temperature (S51). The CMP system begins polishing wafer W (S52). Based on the temperature of polishing liquid 400 detected by temperature detector 270, the CMP system heats or cools the liquid, such as pure water, used to adjust the temperature of slurry 228 (S54). Specifically, the CMP system controls the temperature of pure water 224 based on the temperature of polishing liquid 400 detected by temperature detector 270.

[0073] The CMP apparatus system mixes temperature-controlled liquids such as pure water 224 and slurry 228 in mixer 200 to generate polishing liquid 400, and discharges the generated polishing liquid 400 onto polishing pad 120 (or platform 110) via dripping unit 210 (S54).

[0074] Immediately before supplying polishing liquid 400 to polishing pad 120 (or platen 110), the CMP system detects the temperature of polishing liquid 400 using temperature detector 270 (S55). The CMP system determines whether the temperature of polishing liquid 400 detected by temperature detector 270 matches or does not match the set temperature set in S51 (S56). It should be noted that "the temperature of polishing liquid 400 matches the set temperature set in S51" includes not only "completely matching" but also "a temperature within a predetermined range."

[0075] If the temperature of the polishing liquid 400 is determined to be consistent with the set temperature, the CMP system controls the temperature of the liquid, such as pure water, to be constant through the control device 310 (S57), and the process ends. If the temperature of the polishing liquid 400 is determined to be inconsistent with the set temperature, the CMP system proceeds to the process of S53.

[0076] In the CMP method, the polishing temperature can significantly affect the wafer throughput. This effect becomes particularly significant when polishing thin wafers W. Therefore, in this embodiment, the temperature of the polishing liquid 400 at the outlet of the dripping unit (nozzle) 210 of the mixer 200 is maintained constant, thereby attempting to maintain a constant temperature in the polishing portion of the polishing pad 120 where the wafer W is polished. However, in order to maintain a constant temperature of the polishing liquid 400, if the polishing liquid is heated for a long time before dripping onto the polishing pad 120, the polishing liquid may locally aggregate. Agglomeration of the polishing liquid not only adversely affects the flatness of the polished surface but can also cause damage to the polished surface.

[0077] To address this problem, in this embodiment, a polishing liquid controlled at a predetermined temperature is generated immediately before the polishing section where the polishing pad 120 polishes the wafer W. Therefore, by placing the mixer 200 as close as possible to the polishing section, the mixed slurry 228 is mixed with a temperature-controlled liquid, such as pure water 224, thereby limiting the heating time of the slurry 228 to the period during which the slurry remains in the mixer 200.

[0078] It should be noted that after being supplied from the slurry manufacturer, the slurry 228 is stored at a temperature specified by the manufacturer. During use, the slurry 228 is maintained at room temperature within the temperature-controlled CMP apparatus chamber. Therefore, the slurry 228 stored in tanks 264 and 266 is maintained at a substantially constant temperature. Since the slurry 228 stored in tanks 264 and 266 within the CMP apparatus chamber is introduced into the mixer 200, the slurry 228 is introduced into the mixer 200 at approximately room temperature. Furthermore, the amount of pure water contained in the slurry used to fluidize the abrasive particles is much smaller than the amount of pure water mixed in the mixer 200. Therefore, even without actively controlling the temperature of the slurry 228, simply controlling the temperature of the pure water 224 flowing into the mixer 200 allows the temperature of the mixed polishing liquid 400 discharged from the mixer 200 to be managed.

[0079] According to this embodiment, slurry 228 is not heated before being introduced into mixer 200. Instead, slurry 228 is heated or cooled in mixer 200 using only temperature-controlled pure water 224. This prevents slurry 228 from being abnormally heated and causing localized aggregation. It should be noted that in order to guide temperature-controlled pure water 224 to mixer 200 at a predetermined temperature, the introduction pipe 232 on the output side of the temperature control device 300 should be shortened as much as possible and protected with a heat-insulating material to prevent heat dissipation, thereby achieving a higher temperature control effect.

[0080] It should be noted that if Figure 6As shown, in order to dissipate heat and adjust the temperature (heating / cooling) within the mixer 200, a temperature adjustment mechanism 280, such as a heat-insulating material and / or a heater / cooler, may be provided around the mixer 200. For example, the temperature adjustment mechanism 280 may be controlled by the control device 310. Alternatively, a control device for controlling the temperature adjustment mechanism 280 may be provided independently of the control device 310. In this case, the control device for controlling the temperature adjustment mechanism 280 is connected to, for example, the temperature detector 270, and adjusts the temperature based on temperature information output from the temperature detector 270. However, when heat is supplied from outside the mixer 200 to the mixture of slurry 228 and a liquid, such as pure water 224, a temperature difference may occur between the center portion of the mixer 200 and the wall surface of the housing 202, thereby locally heating the slurry 228 and causing agglomeration. Therefore, from the perspective of homogenizing the polishing liquid 400, the method shown in this embodiment, in which the slurry 228 is mixed with pure water 224 heated to a uniform temperature, is more preferable.

[0081] In addition, in this embodiment, in order to generate the polishing liquid controlled at a predetermined temperature immediately before the polishing portion where the polishing pad 120 polishes the wafer W, the mixer 200 only needs to be arranged so that the pipe, such as the drip unit 210, that supplies the polishing liquid 400 to the polishing pad 120 does not become too long. Figure 7 As shown, the mixer 200 may also be disposed proximate to or adjacent to a lower end or surface of the platform 110 .

[0082] According to this embodiment, to prevent slurry agglomeration, the temperature of the polishing liquid generated by mixing the slurry with a liquid, such as pure water, is kept constant over a short period of time. This allows the polishing temperature of the polishing section to be maintained at a predetermined temperature. In particular, when the slurry is heated with pure water to a predetermined temperature, the heating occurs only while the slurry is in the mixer. This limits the heating time of the slurry and allows the polishing temperature of the polishing section to be maintained at a predetermined temperature. This improves the accuracy of the polished surface and prevents damage, thereby increasing the yield rate of semiconductor manufacturing. It should be noted that the CMP system (CMP apparatus 100) of this embodiment is suitable for polishing workpieces having films, such as oxide films or metal films, formed on their surfaces, as well as workpieces without such films. It is particularly suitable for polishing workpieces having metal films formed on their surfaces.

Claims

1. A CMP apparatus that polishes a surface of a workpiece held by a rotatable polishing head by pressing the workpiece against a freely rotatable platform, wherein: have: a mixer, adjacent to the platform, for mixing the slurry with a liquid other than the slurry; and A temperature regulating unit is used to adjust the temperature of the liquid.

2. The CMP apparatus according to claim 1, wherein The mixer includes a dropping unit for dropping a polishing liquid obtained by mixing the slurry and the liquid onto the platform. The dropping unit is located on the upstream side in the rotation direction of the platform.

3. The CMP apparatus according to claim 2, wherein: The mixer is arranged on the platform.

4. The CMP device according to claim 3, characterized in that: The liquid is pure water.

5. A method for controlling the polishing temperature of a CMP apparatus, wherein the CMP apparatus polishes the surface of a workpiece held by a rotatable polishing head by pressing the workpiece against a freely rotatable platform, wherein the method comprises: Adjust the temperature of liquids other than slurry, The temperature of the polishing liquid formed by mixing the slurry and the liquid is adjusted in a mixer adjacent to the platform.

6. The polishing temperature control method according to claim 5, characterized in that: The polishing liquid is supplied to the upstream side of the polishing head in the rotation direction of the platen.

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