CMP device and polishing temperature control method of the same

Abstract

To provide a polishing device capable of controlling a polishing temperature properly, and to provide a polishing method.SOLUTION: A CMP device 100 presses a workpiece held by a rotary polishing head 50 against a rotary platen 110 to polish a surface of the workpiece. The CMP device includes: a mixer 200 located adjacent to the platen and configured to mix slurry with a liquid other than the slurry; and temperature control means 300 for controlling a temperature of the liquid.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a CMP apparatus for polishing the surface of a semiconductor wafer or the like, and a method for controlling the polishing temperature thereof. [Background technology]

[0002] Conventionally, chemical mechanical polishing (CMP) equipment is used to polish workpieces such as semiconductor wafers using an abrasive or polishing liquid slurry. In polishing processes using CMP equipment, the polishing temperature, which corresponds to the temperature of the wafer or other object being polished during the polishing process, can affect the polishing rate. Specifically, the difference in polishing temperature from the center to the outer edge of the wafer can affect the distribution of the amount of polishing on the wafer. For example, the polishing temperature can have a significant effect on the polishing rate, particularly in metal polishing, among polishing substrates such as silicon and silicon carbide, silicon oxide films, and metal wiring films. With the recent trend toward larger wafer diameters, it may be necessary to more precisely control the polishing temperature.

[0003] Examples of wafer surface polishing using a CMP apparatus are described in Patent Documents 1 to 5. For example, the CMP apparatus described in Patent Document 1 includes a platen that holds a polishing pad and a carrier that can be moved laterally across the polishing pad by an actuator to hold a substrate against the polishing surface of the polishing pad during the polishing process. The apparatus also includes a thermal control system including multiple heaters and coolers that independently control the temperatures of multiple zones on the polishing pad, and a controller, and the controller controls the thermal control system to generate a first zone having a first temperature and a second zone having a second temperature different from the first temperature on the polishing pad.

[0004] Patent Document 2 discloses a method for achieving a highly flat polished surface without leaving polishing scars on the polished wafer. Specifically, the CMP apparatus includes a supply unit that supplies a slurry to the surface of a polishing pad containing water-soluble particles, a holding unit that holds the object to be polished and brings the object into contact with the surface of the polishing pad, a temperature setting unit that is disposed on the surface of the polishing pad and sets the temperature of the surface of the polishing pad, and a control unit that controls the operation of the supply unit, holding unit, and temperature setting unit. The control unit performs a first polishing step in which the object to be polished is polished while the temperature of the surface of the polishing pad is set within a first temperature range, and then performs a second polishing step in which the object to be polished is polished while the temperature of the surface of the polishing pad is set within a second temperature range.

[0005] In Patent Document 3, in order to prevent the coarsening of abrasive particles due to aggregation of the slurry supplied to the CMP apparatus, the slurry supply apparatus includes a sealed slurry bottle, a piping system, a wet nitrogen generator, a wet nitrogen supply pipe, a suction nozzle, a spray nozzle, a temperature regulator, a flow rate control valve, a liquid supply pump, and a control system that controls the operation and flow rate of each liquid supply pump. During polishing using the CMP apparatus, the liquid supply pump is operated intermittently, alternately operating and stopping at regular time intervals. The slurry is agitated by spraying it from the spray nozzle without using an agitator such as a propeller placed inside the slurry bottle.

[0006] In Patent Document 4, when polishing a workpiece having Cu wiring formed by the damascene method, the following three steps are taken in the polishing using a CMP apparatus to prevent the Cu film from remaining unpolished during the CMP process. In the first step, the Cu film is polished using an abrasive-free slurry on a first polishing platen, and polishing of the Cu film is stopped by a barrier metal layer. In the second step, the surface of the semiconductor wafer is polished using a slurry prepared by immediately mixing an abrasive-free slurry and a silica slurry on a second polishing platen, and the Cu film that remained unpolished in the first step is removed. In the third step, the barrier metal layer in areas other than the wiring grooves is polished using silica slurry on a third polishing platen, and Cu wiring is formed inside the wiring grooves.

[0007] Patent Document 5 attempts to suppress variations in the chemical reaction rate of the processed surface caused by an increase in the temperature of the metal film surface due to an exothermic reaction of the metal during planarization polishing of the surface of a wafer having a metal wiring film by the CMP method.To this end, the polishing apparatus is provided with a thermostatic means for controlling the temperature of the air supplied from the air outlet of a wafer carrier having a back plate with an air outlet on its underside that applies a pressing force to the wafer via a pressurized air layer formed by air supplied from the air outlet, and a protective sheet that contacts the wafer and transmits the pressing force applied from the back plate via the pressurized air layer to the wafer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication 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 [Problem to be solved by the invention]

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

[0010] The CMP method is widely used for polishing the surface of wafer substrates. In the CMP method, a polishing pad is placed on a rotating table called a platen, which is rotated. At the same time, the wafer to be polished is also rotated around its center, and polished by the abrasive particles contained in the slurry. The quality of this polishing is affected by the frictional heat generated during polishing, and it has been found that the flatness of the polished surface of the wafer and the occurrence of scratches on the surface are particularly affected by whether or not the temperature of the polishing area rises.

[0011] The peripheral speed of the wafer is high on the outer periphery, and approaches zero near the center. As a result, the relative speed between the polishing pad and the wafer changes depending on the position on the polishing pad due to differences in the peripheral speed of the wafer. This change in relative speed is thought to be one of the causes of changes in the amount of heat generated during polishing. This difference in peripheral speed becomes more pronounced as the wafer diameter increases.

[0012] After completing the formation of a pattern or metal wiring layer on the wafer substrate surface, the wafer may be thinned by grinding. In this case, the substrate thickness varies within the grinding processing tolerance. In a thinned wafer, the thermal resistance varies depending on the local thickness of the wafer and the formed metal wiring pattern, and the amount of polishing heat transmitted and the rate of dissipation change. This may cause deviation from uniform polishing with a constant temperature in the polishing area.

[0013] Patent Document 1 discloses that when polishing a wafer using the CMP method, the polishing pad is divided into multiple zones and the temperature is controlled for each zone using a heater and cooler. While this publication offers the advantage of being able to freely control the polishing profile, it also requires the heater and cooler to be controlled in various ways to measure the temperature of the polishing area and adjust each part of the polishing pad to the appropriate temperature, making the equipment bulky. Furthermore, because polishing pads these days are often thick, the temperature adjusted by the platen is not necessarily transmitted to the wafer.

[0014] Patent Document 2 discloses that polishing is performed multiple times by controlling the surface temperature of the polishing pad between a first temperature at which the polishing pad has a high elastic modulus and maintains the flatness of the surface of the workpiece to be polished, and a second temperature at which the polishing pad causes fewer polishing scratches. The CMP method described in this publication is expected to be very effective under the same polishing conditions, but does not take into account the difference in the amount of processing heat generated due to the difference in the peripheral speed of the wafer between the outer periphery and the center.

[0015] As described in Patent Document 3, when a wafer is polished by the CMP method using a slurry, the temperature of the polishing section can be controlled more accurately by adjusting the temperature of the slurry. However, if the slurry is heated for a long period of time, additives contained in the slurry may be altered, which may promote aggregation. If aggregation occurs in the slurry, it may have an adverse effect on the temperature control of the polishing section by controlling the temperature of the slurry, and may also cause scratches on the wafer surface.

[0016] Furthermore, even when polishing a Cu film on a semiconductor substrate by CMP using multiple polishing plates as described in Patent Document 4, the peripheral speed varies depending on the polishing position on the semiconductor wafer, which can cause differences in the amount of processing heat generated between the platen and the wafer, and these differences in the amount of processing heat generated can affect the wafer properties.

[0017] In the CMP polishing of the wafer surface described in Patent Document 5, when polishing metal wiring, air controlled to a predetermined temperature is ejected onto the backside of the substrate in response to local changes in the wafer surface caused by an exothermic reaction of the metal. This method allows for precise temperature control of the polishing area, but the structure becomes complicated.

[0018] In addition to the above, wafer temperature may also be adjusted by adjusting the temperature of an air-float type head that has an air layer between the head and the wafer, but the air layer may make it difficult for the heat from the head to be transferred to the wafer.

[0019] In addition, the temperature of the polishing section may be controlled by adjusting the temperature of the slurry through the piping that supplies the slurry, but there is a possibility that the temperature of the slurry that has accumulated in the temperature-adjusted piping may change unintentionally.

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

[0021] The first CMP apparatus of the present invention is a CMP apparatus that polishes the surface of a workpiece by pressing the workpiece held by a rotatable polishing head against a rotatable platen, and is characterized in that it comprises a mixer adjacent to the platen that mixes a slurry with a liquid other than the slurry, and a temperature adjustment means that adjusts the temperature of the liquid.

[0022] A second CMP apparatus of the present invention is the CMP apparatus of the first CMP apparatus, characterized in that the mixer is provided with a dripping means that drips a polishing liquid mixed with the slurry and the liquid toward the platen, and the dripping means is located upstream with respect to the rotation direction of the platen.

[0023] A third CMP apparatus of the present invention is the second CMP apparatus, wherein the mixer is disposed on the platen.

[0024] A fourth CMP apparatus of the present invention is the third CMP apparatus, wherein the liquid is pure water.

[0025] The first polishing temperature control method for a CMP apparatus of the present invention is a method for controlling the polishing temperature of a CMP apparatus in which a workpiece held by a rotatable polishing head is pressed against a rotatable platen to polish the surface of the workpiece, characterized in that the temperature of a liquid other than a slurry is adjusted, and the temperature of a polishing liquid obtained by mixing the slurry and the liquid in a mixer adjacent to the platen is adjusted.

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

[0027] According to the present invention, a polishing apparatus and a polishing method capable of appropriately controlling the polishing temperature are provided. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a perspective view of a CMP apparatus according to an embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a CMP apparatus system according to an embodiment. [Figure 3] FIG. 10 is a partial cross-sectional view schematically illustrating an example of a retainer. [Figure 4] FIG. 2 is a schematic diagram illustrating an example of a mixer according to an embodiment. [Figure 5] 1 is a flowchart showing an example of a polishing temperature control method according to an embodiment. [Figure 6] FIG. 10 is a schematic diagram showing an example of a mixer according to Modification 1. [Figure 7] FIG. 10 is a schematic diagram showing an example of a CMP apparatus system according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0029] The CMP apparatus according to the embodiment will be described below with reference to the drawings.

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

[0031] 1, the CMP apparatus 100 includes a polishing head 50 that holds a workpiece, for example, a wafer W, a rotatable platen 110, a polishing pad 120 provided on the platen 110, and a mixer 200. The CMP apparatus 100 also has an air pressure introducing jig, in which an air pressure introducing portion 239 is formed, attached to the vicinity of one side thereof.

[0032] 2, the CMP apparatus 100 polishes the wafer W using a polishing liquid 400, for example, a slurry. The CMP apparatus 100 has an enclosure disposed around the platen 110, which recovers the polishing liquid 400, for example, a slurry, used in polishing between the polishing pad 120 on the upper surface of the platen 110 and the wafer W without leaking it to the outside. Hereinafter, "one type of slurry," "a liquid mixture of multiple slurries," or "a liquid, for example, a liquid mixture of pure water and multiple slurries" may also be referred to simply as "slurry" or "polishing liquid."

[0033] The polishing head 50 is disposed above the platen 110 and the polishing pad 120. The polishing head 50 faces the polishing pad 120. The polishing head 50 faces, for example, a portion of the polishing pad 120.

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

[0035] The polishing pad 120 is formed, for example, in a disk shape. The polishing pad 120 is attached, for example, to the platen 110. The polishing pad 120 is made, for example, of a polyurethane material. The polishing pad 120 is formed, for example, from IC1000™ or IC1400™ manufactured by Nitta DuPont and has a closed-cell structure. Such a polishing pad 120 can, for example, uniformly hold slurry, which is a polishing liquid, within the formed cells. Compared to IC1000, IC1400 has superior polishing processability for metal wiring films and the like, but it may be more difficult to uniformly dissipate frictional heat.

[0036] The mixer 200 is disposed on the polishing pad 120 (or platen 110) at a circumferential position different from that of the polishing head 50. In the example shown in FIG. 1, the mixer 200 is disposed on the polishing pad 120 at a circumferential position opposite that of the polishing head 50. In other words, in the example shown in FIG. 1, the mixer 200 is disposed above the platen 110 and upstream of the polishing head 50 in the direction of rotation of the platen 110. The mixer 200 may also be disposed near the polishing head 50 on the polishing pad 120. Furthermore, the mixer 200 does not have to be disposed on the polishing pad 120 as long as the piping for supplying the polishing liquid 400, e.g., slurry, to the polishing pad 120 is not too long, for example, as long as the mixer 200 is located near (or adjacent to) the platen 110 so that the temperature of the polishing liquid 400 mixed by the mixer 200 does not change substantially.

[0037] The mixer 200 is, for example, a static mixer. However, the mixer 200 may 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 has a dropping means (nozzle) 210, an introduction pipe 232, and a plurality of slurry introduction pipes 234 and 236. The mixer 200 does not have to have a plurality of slurry introduction pipes, and it is sufficient that it has at least one slurry introduction pipe.

[0039] The dripping means 210 is provided on the underside of the mixer 200 near the tip thereof, and drips the polishing liquid, for example, slurry 400, discharged from the mixer 200 onto the polishing pad 120. In the example shown in FIG. 1, the dripping means 210 is provided above the polishing pad 120 (or platen 110) and upstream of the polishing head 50 in the direction of rotation of the platen 110. Note that the dripping means 210 may be located elsewhere as long as it is provided above the polishing pad 120 (or platen 110). For example, the dripping means 210 may be located adjacent to the polishing head 50.

[0040] The introduction pipe 232 is attached to a portion of the mixer 200 substantially opposite to the portion to which the dripping means 210 is attached. In the example shown in Fig. 1, the introduction pipe 232 is attached to the end face of the mixer 200 opposite to the portion to which the dripping means 210 is attached.

[0041] The slurry introduction pipes 234, 236 are attached to a portion of the mixer 200 substantially opposite to the portion to which the dripping means 210 is attached. In the example shown in Fig. 1, the slurry introduction pipes 234, 236 are attached to the side surface of the end of the mixer 200 opposite to the portion to which the dripping means 210 is attached.

[0042] The configuration of the CMP apparatus 100, the control system, and the supply system 500 will be described in more detail below with reference to FIG. 2, the CMP apparatus 100 further includes a motor 112, a rotary shaft 114, a CMP apparatus control unit 150, a compressed air introduction pipe 238, a valve 248, a compressed air source 268, and a temperature detector 270. The valve 248 and the compressed air source 268 may be provided separately from the CMP apparatus 100.

[0043] The supply system 500 includes multiple valves 242, 244, and 246, pumps 252, 254, and 256, a liquid tank 262, multiple slurry tanks 264 and 266, a temperature adjustment device 300, a controller 310 (a pure temperature control device), and a pump controller 320. The supply system 500 may be provided in the CMP apparatus 100 or may be provided separately from the CMP apparatus 100. Alternatively, a portion of the supply system 500 may be provided in the CMP apparatus 100. 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 vary. The CMP apparatus 100 and the supply system 500 may be collectively referred to as a CMP apparatus system.

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

[0045] The rotating shaft 114 is provided at the base or below the platen 110. The rotating shaft 114 is, for example, coaxially connected to the platen 110. The motor 112 is provided at the base or below the rotating shaft 114. The motor 112 is, for example, coaxially connected to the rotating shaft 114. The motor 112 drives the platen 110 and the rotating shaft 114 to rotate around the central axes of the platen 110 and the rotating shaft 114.

[0046] The temperature detector 270 detects, for example, the temperature of the polishing liquid 400. The temperature detector 270 detects (or measures), for example, the temperature immediately before the polishing liquid 400 is supplied to the polishing pad 120 or the platen 110. The temperature detector 270 is disposed, for example, on the polishing pad 120, in the vicinity of the polishing pad 120, in the mixer 200, or in the vicinity of the mixer 200. Note that the temperature detector 270 may also be disposed in a position other than these. The temperature detector 270 is connected to the control device 310. The temperature detector 270 outputs detected temperature information of the polishing liquid 400 to the control device 310.

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

[0048] The plurality of slurry tanks 264, 266 are connected to the mixer 200 via valves 244, 246, pumps 254, 256, and slurry inlet pipes 234, 236, respectively. The plurality of slurry tanks 264, 266 each store a slurry. The plurality of slurry tanks 264, 266 may store the same type of slurry, or may store different types of slurry. The slurry tanks 264, 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 is equipped with a heater and / or a cooler. The temperature adjustment device 300 is connected to an inlet pipe 232. For example, when adjusting the temperature of pure water, the temperature adjustment device 300 is The temperature can be adjusted to a range of 0 to 70 degrees. The temperature adjustment device 300 may be able to adjust the temperature of the pure water to a temperature outside the range of 0 to 70 degrees.

[0050] The control device 310 controls the temperature adjustment device 300. The control device 310 controls the temperature of the liquid, for example, pure water, circulating within the temperature adjustment device 300 based on the temperature detected by, for example, the mixer 200, the vicinity of the mixer 200, the polishing pad 120, or a temperature detector 270 disposed in the vicinity of the polishing pad 120.

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

[0052] The compressed air source 268 is connected to the polishing head 50 via the compressed air inlet 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 has a motor 52, a rotating shaft 54, and a retainer 56. The retainer 56 holds the wafer W therein. The rotating shaft 54 ​​is provided on the upper side of the retainer 56. The retainer 56 is connected, for example, coaxially with the rotating shaft 54.

[0054] The 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 provided so as to be movable in the vertical direction. The rotating shaft 54 ​​controls the motor (not shown) to control the distance between the retainer 56 attached to the lower end of the rotating shaft 54 ​​and the polishing pad 120.

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

[0056] FIG. 3 is a partial cross-sectional view that schematically illustrates an example of the retainer 56. As shown in FIG. The diameter of the lower end of the rotary shaft 54 ​​is larger than the diameter of the portion above the lower end. In the example shown in Fig. 3, the lower end of the rotary shaft 54 ​​is formed in a disk shape.

[0057] The retainer 56 has a head 58, a pressure plate 60, a retaining ring 62, a top ring 64, a spring 66, and a stopper pin 68. The retainer 56 may have components other than the head 58, the pressure plate, the retaining ring 62, the top ring 64, the spring 66, and the stopper pin 68, or may not have at least one of these components.

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

[0059] The top ring 64 is formed in a ring shape and is attached to the lower end of the rotary shaft 54. The top ring 64 has a fitting structure formed on the inner periphery thereof.

[0060] The retaining ring 62 is formed in a ring shape. The retaining ring 62 has fitting portions on both the outer and inner circumferential sides. The fitting portions on the outer circumferential side of the retaining ring 62 fit into the fitting structure of the top ring 64. The retaining ring 62 holds the wafer W at its innermost circumferential portion with the polishing surface facing downward.

[0061] The pressure plate 60 is fitted into a fitting portion on the inner periphery of the retaining ring 62. For example, the pressure plate 60 is fitted into the fitting portion on the inner periphery of the retaining ring 62 with some play. Holes are formed in multiple locations on the outer periphery of the pressure plate 60, and stopper pins 68 can be fitted into these holes. A spring 66 is wound around the stopper pin 68.

[0062] A compressed air passage 70, which is a through-hole, is formed in the center of the rotation shaft 54 ​​of the polishing head 50 and in the central part of the head 58, and compressed air is supplied from the compressed air source 268 shown in FIG. 2 to the air chamber, which is the space formed between the underside of the head 58 and the pressure plate 60, via the compressed air passage 70.

[0063] Hereinafter, the method for polishing the wafer W will be described with reference to FIGS. The polishing head 50 has the wafer W placed within the holding ring 62 of the retainer 56, and drives a vacuum pump (not shown) to suck the wafer W toward the pressure plate 60. The polishing head 50 lowers the head 58 toward the polishing pad 120 (or platen 110) while holding the wafer W by suction. When the head 58 is positioned at a predetermined height above the platen 110, the polishing head 50 stops lowering the head 58 and stops driving the vacuum pump. The polishing head 50 places the wafer W on the polishing pad 120.

[0064] When the wafer W is placed on the polishing pad 120, the platen 110 is driven to rotate by the motor 112, and the polishing liquid 400 is supplied onto the polishing pad 120 from a dripping means 210 attached to a mixer 200 positioned upstream of the polishing head 50 in the direction of rotation of the platen 110.

[0065] When the 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 an air chamber, which is a space formed between the underside of the head 58 and the pressure plate 60. When compressed air is supplied into the air chamber, the air chamber is filled with 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 placed on the underside of the pressure plate 60, when the pressure plate 60 is pressed toward the polishing pad 120, the wafer W is also pressed against the pressure plate 60 and pressed against the polishing pad 120. The wafer W is polished while a polishing liquid 400 is introduced to the interface with the polishing pad 120.

[0066] When the wafer W is pressed against the polishing pad 120, the wafer W is rotated around the rotation axis 54 of the polishing head 50. When the head 58 rotates, the 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 against 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] FIG. 4 is a schematic diagram showing an example of the mixer 200 according to this embodiment. In the example shown in Fig. 4, the mixer 200 has an inlet pipe fitting 222 and a slurry inlet pipe fitting 226. Although not shown in Fig. 4, the mixer 200 may have a plurality of slurry inlet pipe fittings 226. However, the mixer 200 may have only one slurry inlet pipe fitting 226.

[0068] The inlet pipe fitting 222 is attached to the flange at the left end (the flange of the liquid intake portion). The inlet pipe fitting 222 is attached to the inlet pipe 232 shown in Figure 2. The inlet pipe fitting 222 introduces the liquid, the temperature of which has been adjusted by the temperature adjustment device 300, such as pure water 224, into the mixer 200 through a through-hole formed in the center.

[0069] The flange of the liquid intake section is connected to the flange of at least one slurry inlet pipe attachment section. For example, at least one slurry inlet pipe attachment device 226 is attached to at least one branch flange in a direction perpendicular to the flow direction of the liquid, e.g., pure water 224. By attaching a slurry inlet pipe 234 (236) to the slurry inlet pipe attachment device 226, it becomes possible to introduce the prepared slurry 228 from the tank 264 (266) into the mixer 200. Note that, for the sake of convenience, the example shown in FIG. 4 has only one slurry input, but another slurry input section may be provided axially stacked after the pure water input section.

[0070] The mixer 200 mixes liquids, such as pure water 224 and slurry 228, in a mixer section attached downstream of the mixer section by the action of pumps 252, 254, and 256. The mixer section is composed of a cylindrical pipe (casing) 202 with flanges at both ends and a spiral mixer blade 204 disposed within the casing. The pure water 224 and slurry 228 flow axially downward through a space defined by the spiral mixer blade 204, whereby the slurry 228 is mixed into the pure water 224. The mixer 200 drips or sprays the polishing liquid 400 onto the upper surface of the polishing pad 120 from a dripping means (nozzle) 210 attached to the underside of a drip section located downstream of the mixer section (the right end in FIG. 4 ).

[0071] Here, the slurry 228 is appropriately selected depending on the object to be polished. For polishing a wafer W on which Cu wiring or the like is formed, it is desirable to use a slurry containing silica or the like. For polishing a surface on which a wiring layer or the like has not yet been formed, a slurry 228 containing alumina or polymer beads or the like can be used. The slurry 228 may also contain manganese abrasive grains or diamond abrasive grains. The abrasive grains such as silica, alumina, and polymer beads are fine powders with an outer diameter of, for example, about 100 nm. The slurry 228 may contain abrasive grains other than the aforementioned substances, or it may not contain abrasive grains at all.

[0072] FIG. 5 is a flowchart showing an example of a method for controlling the polishing temperature according to this embodiment. The CMP apparatus system sets a use set temperature (S51). The CMP apparatus system starts polishing the wafer W (S52). The CMP apparatus system heats or cools a liquid, such as pure water, for adjusting the temperature of the slurry 228 based on the temperature of the polishing liquid 400 detected by the temperature detector 270 (S54). In other words, the CMP apparatus system controls the temperature of the pure water 224 based on the temperature of the polishing liquid 400 detected by the temperature detector 270.

[0073] The CMP apparatus system mixes a temperature-adjusted liquid, such as pure water 224 and a slurry 228, in a mixer 200 to generate a polishing liquid 400, and then ejects the generated polishing liquid 400 onto the polishing pad 120 (or platen 110) via a dripping means 210 (S54).

[0074] The CMP apparatus system detects the temperature of the polishing liquid 400 using the temperature detector 270 immediately before supplying it to the polishing pad 120 (or platen 110) (S55). The CMP apparatus system determines whether the temperature of the polishing liquid 400 detected by the temperature detector 270 matches the set temperature set in S51 (S56). Note that "the temperature of the polishing liquid 400 matches the set temperature set in S51" includes "complete match" as well as "being within a predetermined temperature range."

[0075] If it is determined that the temperature of the polishing liquid 400 matches the set temperature, the CMP apparatus system controls the liquid, for example, pure water, to maintain a constant temperature via the control device 310 (S57), and ends the process. If it is determined that the temperature of the polishing liquid 400 does not match the set temperature, the CMP apparatus system proceeds to the process of S53.

[0076] In the CMP method, polishing temperature can have a significant impact on throughput. This impact is particularly pronounced when polishing a thin wafer W. For this reason, in this embodiment, an attempt is made to maintain a constant temperature of the polishing section where the wafer W is polished with the polishing pad 120 by maintaining a constant temperature of the polishing liquid 400 at the outlet of the dripping means (nozzle) 210 of the mixer 200. However, if the polishing liquid 400 is heated for a long period of time before being dripped onto the polishing pad 120 in order to maintain a constant temperature, there is a risk of the polishing liquid agglomerating locally. Agglomeration of the polishing liquid not only adversely affects the flatness of the polished surface, but also contributes to the generation of scratches on the polished surface.

[0077] To solve this problem, in this embodiment, a polishing liquid controlled to a predetermined temperature is generated immediately before the polishing section where the wafer W is polished by the polishing pad 120. Therefore, by placing the mixer 200 as close as possible to the polishing section and mixing the slurry 228 with a temperature-adjusted liquid, for example, pure water 224, the heating time of the slurry 228 is limited to the time while the slurry 228 is retained in the mixer 200.

[0078] After being supplied by the slurry manufacturer, the slurry 228 is stored at a temperature specified by the manufacturer and maintained at that temperature in a temperature-controlled CMP apparatus chamber during use. Therefore, the slurry 228 stored in the tanks 264 and 266 is maintained at a substantially constant temperature. Since the slurry 228 stored in the tanks 264 and 266 in the CMP apparatus chamber is introduced into the mixer 200, the slurry 228 is introduced into the mixer 200 at substantially room temperature. Furthermore, the amount of pure water contained in the slurry to fluidize the abrasive grains is significantly less than the amount of pure water mixed in the mixer 200. Therefore, the temperature of the mixed polishing liquid 400 discharged from the mixer 200 can be controlled simply by controlling the temperature of the pure water 224 flowing into the mixer 200, without actively controlling the temperature of the slurry 228.

[0079] According to this embodiment, the slurry 228 is not heated before being introduced into the mixer 200, and in the mixer 200, the slurry 228 is simply heated or cooled with the temperature-adjusted pure water 224, so that it is possible to prevent the slurry 228 from being abnormally heated and from locally agglomerating. In order to introduce the temperature-adjusted pure water 224 into the mixer 200 at a predetermined temperature, the introduction pipe 232 on the output side of the temperature adjustment device 300 should be as short as possible and protected with a heat insulating material to prevent heat radiation, thereby achieving a better temperature adjustment effect.

[0080] As shown in FIG. 6 , a temperature adjustment mechanism 280, such as a heat insulator and / or a heater / cooler, may be provided around the mixer 200 to dissipate heat and adjust the temperature (heating / cooling) in the mixer 200. For example, the control device 310 may control the temperature adjustment mechanism 280. Alternatively, a control device for controlling the temperature adjustment mechanism 280 may be provided separately from the control device 310. In this case, the control device for controlling the temperature adjustment mechanism 280 is connected to, for example, a temperature detector 270 and adjusts the temperature based on temperature information output from the temperature detector 270. However, if heat is supplied from outside the mixer 200 to the mixture of the slurry 228 and a liquid, such as pure water 224, a temperature difference may occur between the center of the mixer 200 and the wall surface of the case 202, causing partial heating of the slurry 228 and the risk of aggregation. Therefore, the method shown in this embodiment, in which the slurry 228 is mixed with the heated pure water 224 at a uniform temperature, is more preferable from the perspective of homogenizing the polishing liquid 400.

[0081] In this embodiment, in order to generate a polishing liquid controlled to a predetermined temperature immediately before the polishing section where the wafer W is polished by the polishing pad 120, the mixer 200 may be disposed so that the piping for supplying the polishing liquid 400 onto the polishing pad 120, for example, the dripping means 210, is not too long. For example, as shown in FIG. 7, the mixer 200 may be disposed near or adjacent to the lower end or lower surface of the platen 110.

[0082] According to this embodiment, in order to prevent the occurrence of aggregation of the slurry, the temperature of the polishing liquid generated by mixing the slurry with a liquid, such as pure water, is brought to a constant temperature in a short time, thereby making it possible to maintain the polishing temperature in the polishing section at a predetermined temperature. In particular, when the polishing liquid is heated with pure water to a predetermined temperature, the heating time for the slurry is limited only while the slurry is retained in the mixer, thereby limiting the heating time for the slurry, making it possible to maintain the polishing temperature in the polishing section at a predetermined temperature. This improves the precision of the polished surface and prevents scratches, thereby improving the yield of semiconductor manufacturing. The CMP apparatus system (CMP apparatus 100) of this embodiment can be used to polish workpieces with films, such as oxide films or metal films, formed on their surfaces, as well as workpieces without films, and may be particularly suitable for polishing workpieces with metal films formed on their surfaces. [Explanation of symbols]

[0083] 50... Polishing head, 52... Motor, 54... Rotating shaft, 56... Retainer, 58... Head, 60... Pressure plate, 62... Retaining ring, 64... Top ring, 66... ​​Spring, 68... Stopper pin, 70... Compressed air passage, 100... CMP apparatus, 110... Platen, 112... Motor, 114... Rotating shaft, 120... Polishing pad, 150... CMP apparatus control section, 200... Mixer (static mixer), 202... Case, 204... Spiral mixer blade, 210... Dripping means (nozzle), 222... Inlet pipe attachment, 224... Liquid (pure water), 226...slurry inlet pipe attachment, 228...slurry, 232...inlet pipe, 234, 236...slurry inlet pipe, 238...compressed air inlet pipe, 239...air pressure inlet section, 242, 244, 246, 248...valves, 252, 254, 256...pump, 262...liquid tank, 264, 266...slurry tank, 268...compressed air source, 270...temperature detector, 300...temperature control device (temperature control means), 310...controller (for pure water temperature control device), 320...pump control device, 400...polishing liquid, 500...supply system, W...wafer

Claims

1. 1. A CMP apparatus for polishing a surface of a workpiece by pressing the workpiece held by a rotatable polishing head against a rotatable platen, a mixer adjacent to the platen for mixing the slurry with a liquid other than the slurry; and a temperature adjusting means for adjusting the temperature of the liquid.

2. the mixer includes a dripping means for dripping a polishing liquid obtained by mixing the slurry and the liquid toward the platen, 2. The CMP apparatus according to claim 1, wherein the dropping means is located upstream in the direction of rotation of the platen.

3. The CMP apparatus of claim 2 , wherein the mixer is disposed on the platen.

4. 4. The CMP apparatus according to claim 3, wherein the liquid is pure water.

5. 1. A CMP apparatus for polishing a surface of a workpiece by pressing the workpiece held by a rotatable polishing head against a rotatable platen, Adjust the temperature of the liquid other than the slurry, A polishing temperature control method for a CMP apparatus, characterized in that the temperature of the polishing liquid obtained by mixing the slurry and the liquid is adjusted in a mixer adjacent to the platen.

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

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