KR20250142778A - CMP Apparatus, and Method for Controlling Polishing Temperature Thereof - Google Patents

Abstract

(Task) Provision of a polishing device and polishing method capable of appropriately controlling polishing temperature.
(Solution) A CMP device (100) for polishing the surface of a workpiece held in a rotatable polishing head (50) by applying pressure to the workpiece with a rotatable platen (110), characterized in that it comprises a mixer (200) adjacent to the platen for mixing slurry and a liquid other than slurry, and a temperature control means (300) for adjusting the temperature of the liquid.

Description

CMP Apparatus and Method for Controlling Polishing Temperature Thereof

The present invention relates to a CMP device for polishing a semiconductor wafer surface, etc., and a polishing temperature control method thereof.

Conventionally, in polishing processes using chemical mechanical polishing (CMP) equipment, it is known to polish workpieces such as semiconductor substrate wafers using a slurry of abrasives or polishing liquids. In polishing processes using CMP equipment, the polishing temperature corresponding to the temperature of the wafer, which is the polishing part during the polishing process, may affect the polishing rate. Specifically, the difference in polishing temperature from the center of the wafer to the outer edge may affect the polishing amount distribution of the wafer. For example, among polishing processes targeting substrates such as silicon and silicon carbide, silicon oxide films, and metal wiring films, the influence of the polishing temperature on the polishing rate may be significant, especially in metal polishing. With the recent increase in the diameter of wafers, it may become necessary to control the polishing temperature with higher precision.

Examples of polishing a wafer surface using a CMP device are described in Patent Documents 1 to 5. For example, the CMP device described in Patent Document 1 includes a platen for holding a polishing pad, and a carrier that can move laterally across the polishing pad by an actuator to hold a substrate against the polishing surface of the polishing pad during the polishing process. In addition, the device includes a thermal control system including a plurality of heaters and coolers for independently controlling the temperatures of a plurality of regions on the polishing pad, and a controller, and the controller controls the thermal control system to create a first region having a first temperature and a second region having a second temperature different from the first temperature on the polishing pad.

Patent Document 2 discloses a method for polishing a wafer without leaving polishing marks and for making the polishing surface highly flat. Specifically, the CMP device comprises a supply unit that supplies slurry to a surface portion of a polishing pad containing water-soluble particles, a holding unit that holds an object to be polished and brings the object to contact the surface portion of the polishing pad, a temperature setting unit that is arranged on the surface portion of the polishing pad and sets the temperature of the surface portion of the polishing pad, and a control unit that controls the operations of the supply unit, the holding unit, and the temperature setting unit. The control unit performs a first polishing process of polishing an object to be polished while the temperature of the surface portion of the polishing pad is set within a first temperature range, and then performs a second polishing process of polishing an object to be polished while the temperature of the surface portion of the polishing pad is set within a second temperature range.

In Patent Document 3, in order to suppress coarsening of abrasive particles due to coagulation of slurry supplied to a CMP device, a slurry supply device is provided with a sealed slurry bottle, a piping system, a wet nitrogen generating device, a piping for supplying wet nitrogen, a suction nozzle, a jet nozzle, a temperature controller, a flow rate control valve, a feed pump, and a control system for controlling the operation or flow rate of each feed pump. During polishing by the CMP device, the feed pump is intermittently operated by alternately operating and stopping it at regular time intervals. The slurry is stirred by jetting the slurry from the jet nozzle without using a stirring device such as a propeller placed inside the slurry bottle.

In Patent Document 4, in polishing a workpiece having Cu wiring formed by a damascene method, in order to prevent unpolished Cu films in the CMP process, the polishing using a CMP device involves the following three steps. In the first step, the Cu film is polished using an abrasive-free slurry by a first polishing platen, and the polishing of the Cu film is stopped at a barrier metal layer. In the second step, the surface of a semiconductor wafer is polished using a slurry obtained by mixing the abrasive-free slurry and the silica slurry just before by a second polishing platen, so as to remove the Cu film that was not locally polished in the first step. In the third step, the barrier metal layer is polished in an area other than the wiring grooves using a silica slurry by a third polishing platen, so as to form Cu wiring inside the wiring grooves.

In Patent Document 5, in the planar polishing of a wafer surface having a metal wiring film by the CMP method, an attempt is made to suppress the temperature of the metal film surface rising due to the exothermic reaction of the metal system and the occurrence of uneven chemical reaction speed of the machined surface. Therefore, a polishing device is provided with a back plate having an air outlet on the lower surface and applying a pressure force to the wafer through a pressure air layer formed by air supplied from the air outlet, and a temperature control means for controlling the temperature of the air supplied from the air outlet of a wafer carrier having a protective sheet that contacts the wafer and transmits the pressure force applied from the back plate through the pressure air layer to the wafer.

Japanese Patent Publication No. 2022-529635 Japanese Patent Publication No. 2012-178450 Japanese Patent Publication No. 2000-158339 Japanese Patent Publication No. 2003-115488 Japanese Patent Publication No. 2006-237035

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

The chemical mechanical polishing (CMP) method is widely used for polishing the surface of wafer substrates. In this method, a polishing pad is placed on a rotating platen, called a platen, and the platen is rotated. The wafer, the target of polishing, is also rotated around its center, and abrasive grains contained in the slurry are used to polish the wafer. The quality of this polishing is significantly affected by the frictional heat generated during polishing. In particular, it has been revealed that the flatness of the polished surface and the occurrence of scratches on the surface are affected by whether or not the temperature of the polishing area rises.

The circumferential velocity of the wafer is high at the outer periphery, while it approaches zero infinitely near the center. Therefore, the relative velocity between the polishing pad and the wafer varies depending on the position of the polishing pad due to the difference in the wafer's circumferential velocity. This variation in relative velocity is thought to be one factor in the variation in heat generated during polishing. This difference in circumferential velocity is more pronounced for larger wafer diameters.

In addition, after the formation of a pattern or metal wiring layer on the wafer substrate surface is completed, the wafer may be thinned by grinding. In this case, the substrate thickness changes within the processing error of the grinding. In a thinned wafer, the thermal resistance changes depending on the local thickness of the wafer or the formed metal wiring pattern, and the amount of polishing heat transmitted or the dissipation speed changes. Accordingly, there is a concern that the polishing section may deviate from the same polishing process in which the temperature is maintained constant.

Patent Document 1 discloses a method for dividing a polishing pad into multiple regions and controlling the temperature of each region using a heater and cooler when polishing a wafer using the CMP method. While this disclosure offers the advantage of arbitrarily controlling the polishing profile, it requires various heater and cooler controls to measure the temperature of the polishing section and to adjust each region of the polishing pad to a temperature corresponding to its own, resulting in a large-scale device. Furthermore, many recent polishing pads are thick, so the temperature controlled by the platen is not necessarily transmitted to the wafer.

Patent Document 2 discloses a method for performing multiple polishing cycles by controlling the surface temperature of a polishing pad to a first temperature that maintains the flatness of the surface of the workpiece due to the high elastic modulus of the polishing pad, and a second temperature that minimizes the occurrence of polishing scratches caused by the polishing pad. While the CMP method described in this publication is believed to yield significant results under identical polishing conditions, it does not take into account differences in the amount of processing heat generated due to differences in the peripheral speed of the wafer between its periphery and center.

In addition, as described in Patent Document 3, when polishing a wafer using the CMP method using a slurry, the temperature of the polishing section can be controlled with higher precision by controlling the temperature of the slurry. However, if the slurry is heated for a long time, there is a risk that the additives contained in the slurry will deteriorate and promote agglomeration. If agglomeration occurs within the slurry, it will have a negative effect on the temperature control of the polishing section due to the slurry temperature control, and there is also a risk of scratches occurring on the wafer surface.

Even when polishing a Cu film on a semiconductor substrate using the CMP method using multiple polishing plates, as described in Patent Document 4, differences in circumferential speed occur depending on the polishing position of the semiconductor wafer. Accordingly, there is a concern that differences in the amount of processing heat generated between the platen and the wafer may occur, and there is a concern that differences in the amount of processing heat generated may affect the wafer properties.

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 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.

In addition to the above, there are cases where the temperature of the wafer is adjusted by adjusting the temperature of an air float type head having an air layer between the head and the wafer, but there is a possibility that the heat of the head may be difficult to transfer to the wafer due to the air layer.

Also, in some cases, the temperature of the polishing section is controlled by adjusting the temperature of the slurry by adjusting the temperature of the pipe supplying the slurry, but there is a possibility that the temperature of the slurry remaining in the section of the pipe where the temperature is adjusted may change unintentionally.

The present invention has been made in light of the above points, and provides a polishing device and a polishing method capable of appropriately controlling the polishing temperature.

The first CMP device of the present invention is a CMP device that polishes the surface of a workpiece held in a rotatable polishing head by pressing the workpiece with a rotatable platen, and is characterized by having a mixer adjacent to the platen that mixes slurry and a liquid other than slurry, and a temperature control means that adjusts the temperature of the liquid.

The second CMP device of the present invention is a CMP device characterized in that, in the first CMP device, the mixer has a dropping means for dropping a polishing liquid mixed with the slurry and the liquid toward the platen, and the dropping means is located on the upstream side with respect to the rotational direction of the platen.

The third CMP device of the present invention is a CMP device in which the mixer is disposed on the platen in the second CMP device.

The fourth CMP device of the present invention is a CMP device characterized in that, in the third CMP device, the liquid is pure water.

The polishing temperature control method of the first CMP device of the present invention is a polishing temperature control method of a CMP device, characterized in that the temperature of a liquid other than slurry is adjusted in a CMP device that polishes the surface of a workpiece held in a rotatable polishing head by pressing the workpiece with a rotatable platen, and the temperature of a polishing liquid obtained by mixing slurry and the liquid is adjusted by a mixer adjacent to the platen.

The polishing temperature control method of the second CMP device of the present invention is a polishing temperature control method of the CMP device, characterized in that, in the polishing temperature control method of the first CMP device, the polishing liquid is supplied to an upstream side of the polishing head with respect to the rotational direction of the platen.

According to the present invention, a polishing device and a polishing method capable of appropriately controlling a polishing temperature are provided.

[Figure 1] A perspective view of a CMP device according to an embodiment.
[Figure 2] This is a schematic diagram showing an example of a CMP device system according to an embodiment.
[Figure 3] This is a partial cross-sectional view schematically showing an example of a retainer.
[Figure 4] This is a schematic diagram showing an example of a mixer according to an embodiment.
[Figure 5] This is a flowchart showing an example of a method for controlling polishing temperature according to an embodiment.
[Figure 6] This is a schematic diagram showing an example of a mixer according to Variant 1.
[Figure 7] This is a schematic diagram showing an example of a CMP device system according to Variant Example 2.

Hereinafter, a CMP device according to an embodiment will be described using drawings.

Fig. 1 is a perspective view of a CMP device (100) according to the present embodiment, and Fig. 2 is a schematic diagram showing an example of a CMP device system according to the present embodiment.

In Fig. 1, a CMP device (100) is provided with a polishing head (50) for holding a workpiece, for example, a wafer (W), a rotatable platen (110), a polishing pad (120) installed on the platen (110), and a mixer (200). In addition, the CMP device (100) is provided with an air pressure inlet fixture having an air pressure inlet (239) formed near one side thereof.

The CMP device (100) polishes a wafer (W) using a polishing liquid (400), for example, a slurry, as shown in Fig. 2. The CMP device (100) has a surrounding member arranged around the platen (110), so that the polishing liquid (400), for example, the slurry, used in polishing between the polishing pad (120) on the upper surface of the platen (110) and the wafer (W) is recovered without leaking to the outside. Hereinafter, "one type of slurry", "a liquid mixed with a plurality of slurries", or "a liquid, for example, pure water or a liquid mixed with a plurality of slurries" may also be simply referred to as "slurry" or "polishing liquid".

The polishing head (50) is placed on 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 part of the polishing pad (120).

The platen (110) is formed, for example, in a disc shape. The diameter of the platen (110) is, for example, larger than the diameter of the polishing head (50).

The polishing pad (120) is formed, for example, in a disk shape. The polishing pad (120) is installed by being attached to, for example, the platen (110). The polishing pad (120) is, for example, a polishing pad made of a polyurethane material. The polishing pad (120) is formed, for example, of IC1000(TM) or IC1400(TM) manufactured by NITTA DuPont, and has an independent foam structure. Such a polishing pad (120) can evenly maintain a slurry, which is a polishing liquid, within the formed foam. Although the IC1400 is superior to the IC1000 in terms of polishing processability of metal wiring films, etc., it is possible that it is difficult to evenly dissipate frictional heat.

The mixer (200) is arranged at a different circumferential position from the polishing head (50) on the polishing pad (120) (or platen (110)). In the example shown in Fig. 1, the mixer (200) is arranged at a circumferential position opposite to the polishing head (50) on the polishing pad (120). In other words, in the example shown in Fig. 1, the mixer (200) is installed above the platen (110) and upstream of the polishing head (50) with respect to the rotational direction of the platen (110). In addition, the mixer (200) may be arranged near the polishing head (50) on the polishing pad (120). In addition, the mixer (200) may not be placed on the polishing pad (120) as long as the pipe supplying the polishing liquid (400), for example, the slurry, to the polishing pad (120) is not too long, for example, the temperature of the polishing liquid (400) mixed by the mixer (200) is hardly changed, and is located near (or adjacent to) the platen (110).

The mixer (200) is, for example, a static mixer. Alternatively, 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.

The mixer (200) has a dropping means (nozzle) (210), an inlet pipe (232), and a plurality of slurry inlet pipes (234, 236). In addition, the mixer (200) may not have a plurality of slurry inlet pipes, and it is preferable to have at least one slurry inlet pipe.

The loading means (210) is installed on the lower surface near the tip of the mixer (200) and drops 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 loading means (210) is installed above the polishing pad (120) (or platen (110)) and upstream of the polishing head (50) with respect to the rotational direction of the platen (110). In addition, the loading means (210) may be arranged at another location as long as it is installed above the polishing pad (120) (or platen (110)). For example, the loading means (210) may be arranged adjacent to the polishing head (50).

The inlet pipe (232) is attached to a portion of the mixer (200) that is almost opposite to the portion to which the loading means (210) is attached. In the example shown in Fig. 1, the inlet pipe (232) is attached to the end surface of the mixer (200) that is opposite to the portion to which the loading means (210) is attached.

The slurry inlet pipe (234, 236) is attached to a portion of the mixer (200) that is almost opposite to the portion to which the loading means (210) is attached. In the example shown in Fig. 1, the slurry inlet pipe (234, 236) is attached to the side of the end portion of the mixer (200) that is opposite to the portion to which the loading means (210) is attached.

Hereinafter, the configuration and control system and supply system (500) of the CMP device (100) will be described in more detail with reference to FIG. 2.

In the example shown in Fig. 2, the CMP device (100) further includes a motor (112), a rotation shaft (114), a CMP device control unit (150), a compressed air inlet pipe (238), a valve (248), a compressed air source (268), a temperature detector (270), etc. In addition, the valve (248) and the compressed air source (268) may be installed separately from the CMP device (100).

The supply system (500) is provided with a plurality of valves (242, 244, 246), pumps (252, 254, 256), a liquid tank (262), a plurality of slurry tanks (264, 266), a temperature control device (300), a control device (310) (of a pure water temperature control device), and a pump control device (320). The supply system (500) may be installed in the CMP device (100) or may be installed separately from the CMP device (100). In addition, a part of the supply system (500) may be installed in the CMP device (100). In addition, the supply system (500) may be provided with only one slurry tank. In this case, the number of valves and the number of pumps of the supply system (500) may also be changed. Additionally, the CMP device (100) and the supply system (500) are sometimes collectively referred to as a CMP device system.

The CMP device control unit (150) controls each part of the CMP device (100). The CMP device control unit (150) controls, for example, the rotation/stop of the motor (52) of the polishing head (50) or the motor (112) of the platen (110).

The rotation shaft (114) is installed at the base or lower side of the platen (110). The rotation shaft (114) is, for example, coaxially connected to the platen (110). The motor (112) is installed at the base or lower side of the rotation shaft (114). The motor (112) is, for example, coaxially connected to the rotation shaft (114). The motor (112) drives the platen (110) and the rotation shaft (114) to rotate about the central axis of the platen (110) and the rotation shaft (114).

The temperature detector (270) detects, for example, the temperature of the polishing liquid (400). The temperature detector (270) detects (or measures) the temperature immediately before the polishing liquid (400) is supplied to, for example, the polishing pad (120) or the platen (110). The temperature detector (270) is disposed, for example, on the polishing pad (120), near the polishing pad (120), the mixer (200), or near the mixer (200). In addition, the temperature detector (270) may be disposed at a location other than these. The temperature detector (270) is connected to the control device (310). The temperature detector (270) outputs the detected temperature information of the polishing liquid (400) to the control device (310).

The liquid tank (262) is connected to the temperature control device (300) via a valve (242) and a pump (252). The liquid tank (262) stores a liquid other than slurry, for example, pure water. The liquid other than slurry stored in the liquid tank (262) is used, for example, for temperature control of the slurry. The liquid tank (262) supplies the stored liquid, for example, pure water, to the temperature control device (300).

A plurality of slurry tanks (264, 266) are connected to a mixer (200) via valves (244, 246), pumps (254, 256), and slurry inlet pipes (234, 236), respectively. The plurality of slurry tanks (264, 266) store slurry, respectively. 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 slurry they store to the mixer (200).

The temperature control device (300) cools and/or heats a liquid such as pure water. The temperature control device (300) is equipped with a heater and/or a cooler. The temperature control device (300) is connected to an inlet pipe (232). For example, when controlling the temperature of pure water, the temperature control device (300) can be controlled within a range of 0 to 70 degrees. In addition, the temperature control device (300) may be capable of controlling the temperature of pure water outside the range of 0 to 70 degrees.

The control device (310) controls the temperature control device (300). The control device (310) controls the temperature of a liquid, for example, pure water, circulating in the temperature control device (300) based on the temperature detected by a temperature detector (270) disposed, for example, in the mixer (200), near the mixer (200), near the polishing pad (120), or near the polishing pad (120).

The pump control device (320) controls the operation of the pumps (252, 254, 256). The pump control device (320) inputs output such as control information to the control device (310) of the temperature control device (300).

The compressed air source (268) is connected to the polishing head (50) via a compressed air inlet pipe (238) and a valve (248). The compressed air source (268) supplies compressed air, such as factory air, to the polishing head (50).

The polishing head (50) is equipped with a motor (52), a rotation shaft (54), and a retainer (56). The retainer (56) holds a wafer (W) inside. The retainer (56) has a rotation shaft (54) installed on the upper side. The retainer (56) is, for example, coaxially connected to the rotation shaft (54).

The rotating shaft (54) has a motor (52) installed on the upper or top portion. The rotating shaft (54) is, for example, coaxially connected to the motor (52). The rotating shaft (54) is installed so as to be movable in the up-and-down direction. The rotating shaft (54) controls the gap between the retainer (56) attached to the lower portion of the rotating shaft (54) and the polishing pad (120) by controlling a motor, which is not shown in the drawing.

The motor (52) drives and rotates the retainer (56) (wafer (W)) and the rotation shaft (54) around the central axis of the retainer (56) (wafer (W)) and the rotation shaft (54).

Figure 3 is a partial cross-sectional view schematically showing an example of a retainer (56).

The diameter of the lower portion of the rotation shaft (54) is larger than the diameter of the upper portion. In the example shown in Fig. 3, the lower portion of the rotation shaft (54) is formed in a disc shape.

The retainer (56) includes a head (58), a pressure plate (60), a holding ring (62), a top ring (64), a spring (66), a stopper pin (68), etc. The retainer (56) may have a configuration other than the head (58), the pressure plate, the holding ring (62), the top ring (64), the spring (66), and the stopper pin (68), and may not have at least one of these.

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

The top ring (64) is formed in a ring shape. The top ring (64) is attached to the lower end of the rotation shaft (54). The top ring (64) has a fitting structure formed on the inner circumference.

The holding ring (62) is formed in a ring shape. The holding ring (62) has a fitting portion on each of the outer and inner periphery sides. The fitting portion of the outer periphery of the holding ring (62) fits into the fitting structure of the top ring (64). The holding ring (62) holds the wafer (W) with the polished surface facing downward at the innermost periphery.

The pressure plate (60) is fitted into the fitting portion on the inner circumference of the holding ring (62). For example, the pressure plate (60) is fitted into the fitting portion on the inner circumference of the holding ring (62) with a gap. Holes are formed in a plurality of locations on the outer circumference of the pressure plate (60), and a stopper pin (68) can be fitted into these holes. A spring (66) is wound around the stopper pin (68).

A compressed air passage (70), which is a through hole, is formed at the center of the rotation axis (54) of the polishing head (50) and the center 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 lower surface of the head (58) and the pressure plate (60), through the compressed air passage (70).

Hereinafter, a method for polishing a wafer (W) will be described with reference to FIGS. 2 and 3.

The polishing head (50) places a wafer (W) in the holding ring (62) of the retainer (56) and drives a vacuum pump, not shown in the drawing, 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 supporting the wafer (W) by sucking it. When the head (58) is placed at a position a predetermined height away from 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).

When a wafer (W) is placed on a polishing pad (120), the platen (110) is driven by a motor (112) to rotate, and polishing liquid (400) is supplied from a loading means (210) attached to a mixer (200) placed upstream of the polishing head (50) with respect to the rotational direction of the platen (110) on the polishing pad (120).

When the wafer (W) is placed on the polishing pad (120), compressed air is supplied into the air chamber, which is the space formed between the lower surface of the head (58) and the pressure plate (60), from a compressed air source (268) such as factory air, through a valve (248) or a compressed air inlet pipe (238). When the compressed air is supplied into the air chamber, the air chamber is filled with the compressed air. The pressure plate (60) is pressed toward the polishing pad (120) by the air pressure of the compressed air filled in the air chamber. Since the wafer (W) is arranged 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 against the pressure plate (60) and pressed against the polishing pad (120). The wafer (W) is polished while the polishing liquid (400) is guided to the interface with the polishing pad (120).

In addition, when pressing the wafer (W) with 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) through the stopper pin (68). The rotation of the pressure plate (60) is transmitted to the wafer (W) pressed by the pressure plate (60), and the wafer (W) also rotates. As a result, the wafer (W) is pressed against the polishing pad (120) while rotating.

Figure 4 is a schematic diagram showing an example of a mixer (200) according to the present embodiment.

In the example shown in Fig. 4, the mixer (200) is provided with an inlet pipe attachment (222) and a slurry inlet pipe attachment (226). In addition, although not shown in Fig. 4, the mixer (200) has a plurality of slurry inlet pipe attachments (226). In addition, the mixer (200) may be provided with only one slurry inlet pipe attachment (226).

The inlet pipe attachment (222) is attached to the flange (liquid introduction flange) at the left end. The inlet pipe (232) shown in Fig. 2 is attached to the inlet pipe attachment (222). The inlet pipe attachment (222) introduces a liquid, for example, pure water (224), the temperature of which has been adjusted by the temperature control device (300), into the mixer (200) through a through hole formed in the center.

The flange of the liquid introduction section is connected to the flange of at least one slurry inlet pipe attachment section. For example, at least one slurry inlet pipe attachment port (226) is attached to at least one branch flange in a direction perpendicular to the direction in which the liquid, for example, pure water (224) flows. By attaching the slurry inlet pipe (234) (slurry inlet pipe (236)) to the slurry inlet pipe attachment port (226), it becomes possible to introduce the slurry (228) adjusted from the tank (264) (tank (266)) into the mixer (200). In addition, in the example shown in Fig. 4, for the sake of convenience of explanation, only one slurry input is provided, but another slurry input section may be installed axially behind the pure water input section.

The mixer (200) mixes liquids, for example, pure water (224) and slurry (228), by the action of each pump (252, 254, and 256), by a mixer unit attached to the downstream side, which is the side through which the pure water (224) and slurry (228) flow, when the flange side of the liquid inlet section and the flange side of at least one slurry inlet pipe attachment section are referred to as the upstream side. The mixer unit is composed of a cylindrical tube (case) (202) having flanges attached to both ends and a spiral mixer blade (204) arranged within the case. The pure water (224) and slurry (228) flow axially through the space formed by the spiral mixer blade (204), so that the slurry (228) is mixed into the pure water (224). The mixer (200) drops or sprays polishing liquid (400) onto the upper surface of the polishing pad (120) from a dropping means (nozzle) (210) attached to the lower surface of the dropping unit installed downstream of the mixer unit (right side in FIG. 4).

Here, the slurry (228) is appropriately selected in accordance with the polishing target, but when polishing a wafer (W) on which Cu wiring, etc. is formed, it is preferable to use a slurry containing silica, etc., and when polishing a surface on which a wiring layer, etc. is not yet formed, a slurry (228) containing alumina or polymer beads, etc. can be used. In addition, the slurry (228) may also contain manganese abrasive grains or diamond abrasive grains. The silica, alumina, or polymer beads as the abrasive grains are, for example, fine particles having an outer diameter of about 100 nm. In addition, the slurry (228) may contain abrasive grains other than the above-mentioned substances, or may not contain abrasive grains.

Fig. 5 is a flowchart showing an example of a method for controlling polishing temperature according to the present embodiment.

The CMP device system sets the usage temperature (S51). The CMP device system starts polishing the wafer (W) (S52). The CMP device system heats or cools a liquid, for example, pure water, to adjust the temperature of the slurry (228) based on the temperature of the polishing liquid (400) detected by the temperature detector (270) (S54). That is, the CMP device system controls the temperature of the pure water (224) based on the temperature of the polishing liquid (400) detected by the temperature detector (270).

The CMP device system mixes temperature-controlled liquids, for example, pure water (224) and slurry (228), with a mixer (200) to produce a polishing liquid (400), and discharges the produced polishing liquid (400) onto a polishing pad (120) (or platen (110)) through a dropping means (210) (S54).

The CMP device system detects the temperature of the polishing liquid (400) by the temperature detector (270) immediately before supplying it to the polishing pad (120) (or platen (110)) (S55). The CMP device system determines whether the temperature of the polishing liquid (400) detected by the temperature detector (270) matches the set temperature set in S51 or not (S56). In addition, "the temperature of the polishing liquid (400) matches the set temperature set in S51" includes "the temperature being within a predetermined range" in addition to "the temperature being completely matched."

If it is determined that the temperature of the polishing liquid (400) matches the set temperature, the CMP device system controls the temperature of the liquid, for example, pure water, to be maintained constant through the control device (310) (S57) and terminates the processing. If it is determined that the temperature of the polishing liquid (400) does not match the set temperature, the CMP device system proceeds to the processing of S53.

In the CMP method, the polishing temperature can have a significant effect on throughput. This effect becomes particularly noticeable when polishing a thin-layered wafer (W). Therefore, in the present embodiment, an attempt is made to maintain the temperature of the polishing section where the wafer (W) is polished with the polishing pad (120) constant by maintaining the temperature of the polishing liquid (400) at the outlet of the dropping means (nozzle) (210) of the mixer (200) constant. However, if the polishing liquid is heated for a long time before being dropped onto the polishing pad (120) in order to maintain the temperature of the polishing liquid (400) constant, there is a risk that the polishing liquid may locally coagulate. Coagulation of the polishing liquid not only adversely affects the flatness of the polishing surface, but also becomes a factor in the occurrence of scratches on the polishing surface.

To resolve these defects, in the present embodiment, a polishing liquid controlled to a predetermined temperature is generated right in front of a polishing section where a wafer (W) is polished with a polishing pad (120). Therefore, the mixing device (200) is positioned as close to the polishing section as possible, and the slurry (228) is mixed with a temperature-controlled liquid, for example, pure water (224), thereby limiting the heating time of the slurry (228) to the time it remains in the mixer (200).

In addition, the slurry (228) is stored at the temperature specified by the slurry maker after being supplied from the slurry maker, and is maintained at room temperature in a temperature-controlled CMP device room when in use. Therefore, the slurry (228) maintained in the tanks (264, 266) is maintained at an almost constant temperature. Since the slurry (228) stored in the tanks (264, 266) in the CMP device room is introduced into the mixer (200), the slurry (228) is introduced into the mixer (200) at almost room temperature. In addition, the amount of pure water included in the slurry for fluidizing the abrasive particles is much smaller than the amount of pure water mixed into the mixer (200). Therefore, even if the temperature of the slurry (228) is not actively controlled, the temperature of the mixed polishing liquid (400) discharged from the mixer (200) can be managed simply by controlling the temperature of the pure water (224) flowing into the mixer (200).

According to the present embodiment, since the slurry (228) is not heated prior to introduction into the mixer (200), and the mixer (200) only heats or cools the slurry (228) with temperature-controlled pure water (224), it is possible to prevent the slurry (228) from being overheated and locally coagulating. In addition, in order to introduce the temperature-controlled pure water (224) into the mixer (200) at a predetermined temperature, the inlet pipe (232) on the output side of the temperature control device (300) is made as short as possible and protected with an insulating material to prevent heat radiation, thereby achieving a better temperature control effect.

In addition, as shown in Fig. 6, in order to dissipate heat and control temperature (heating/cooling) in the mixer (200), a temperature control mechanism (280) such as an insulating material and/or a heater/cooler may be installed around the mixer (200). For example, the control device (310) may control the temperature control mechanism (280). In addition, a control device that controls the temperature control mechanism (280) may be installed separately from the control device (310). In this case, the control device that controls the temperature control mechanism (280) is connected to, for example, a temperature detector (270) and controls the temperature based on temperature information output from the temperature detector (270). However, if heat is supplied from the outside of the mixer (200) to the mixture of slurry (228) and liquid, for example, pure water (224), a temperature difference occurs between the central portion of the interior of the mixer (200) and the wall surface of the case (202), and the slurry (228) is partially heated, which may cause coagulation. Therefore, the method shown in the present embodiment, in which the slurry (228) is mixed with the heated, uniformly temperature pure water (224), is more preferable from the viewpoint of uniformity of the polishing liquid (400).

In addition, in the present embodiment, since a polishing liquid controlled to a predetermined temperature is generated right in front of a polishing section where a wafer (W) is polished with a polishing pad (120), it is preferable that the mixer (200) be positioned so that a pipe, for example, a dropping means (210) for supplying the polishing liquid (400) onto the polishing pad (120) does not become excessively long. For example, as shown in Fig. 7, the mixer (200) may be positioned near or adjacent to the lower end or lower surface of the platen (110).

According to the present embodiment, in order to prevent the occurrence of slurry agglomeration, etc., the temperature of the polishing liquid generated by mixing the slurry and a liquid, such as pure water, is kept at a constant temperature in a short period of time, so that the polishing temperature in the polishing section can be maintained at a predetermined temperature. In particular, when the slurry is heated with pure water to bring the polishing liquid to a predetermined temperature, the heating time of the slurry is limited only while the slurry remains in the mixer, so that the polishing temperature in the polishing section can be maintained at a predetermined temperature. Accordingly, the precision of the polished surface is improved, and the occurrence of scratches, etc. can be prevented, thereby improving the yield of semiconductor manufacturing. In addition, the CMP device system (CMP device (100)) of the present embodiment can be applied to polishing a workpiece having a film, such as an oxide film or a metal film, formed on the surface, or a workpiece having no film formed thereon, and is particularly suitable for polishing a workpiece having a metal film formed on the surface.

50… polishing head, 52… motor, 54… rotating shaft, 56… retainer,
58… head, 60… pressure plate, 62… holding ring,
64… top ring, 66… spring, 68… stopper pin,
70… compressed air passage, 100… CMP device, 110… platen,
112… motor, 114… rotating shaft, 120… polishing pad,
150… CMP device control unit, 200… mixer (static mixer),
202… case, 204… spiral mixer blade,
210… loading 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,
242, 244, 246, 248… valves, 252, 254, 256… pumps,
262… liquid tank, 264, 266… slurry tank,
268… compressed air source, 270… temperature detector,
300… temperature control device (temperature control means),
310… (control device of pure temperature control device),
320… pump control device, 400… polishing liquid, 500… supply system,
W… wafer

Claims (6)

In a CMP device that polishes the surface of a workpiece held in a rotatable polishing head by applying pressure to the workpiece with a rotatable platen,
A mixer adjacent to the above platen, for mixing slurry and a liquid other than slurry,
A temperature control means for adjusting the temperature of the above liquid
A CMP device characterized by having: The above mixer is equipped with a dropping means for dropping a polishing liquid mixed with the slurry and the liquid toward the platen,
The CMP device described in claim 1, characterized in that the loading means is located on the upstream side with respect to the rotation direction of the platen. The above mixer is a CMP device described in claim 2, which is arranged on the platen. A CMP device according to claim 3, characterized in that the liquid is pure. In a CMP device that presses a workpiece held in a rotatable polishing head with a rotatable platen to polish the surface of the workpiece,
Adjust the temperature of liquids other than slurry,
A polishing temperature control method of a CMP device, characterized in that the temperature of a polishing liquid mixed with slurry and the liquid is controlled by a mixer adjacent to the platen. A polishing temperature control method according to claim 5, characterized in that the polishing liquid is supplied to an upstream side of the polishing head with respect to the rotational direction of the platen.