KR100914608B1 - Polishing apparatus and polishing method - Google Patents

Abstract

Disclosed are a polishing apparatus and a polishing method capable of polishing a polishing object. The polishing apparatus may include a polishing platen, a polishing head portion capable of polishing the polishing object while moving relative to the polishing platen, and includes a cooling portion capable of cooling the portion of the polishing object polished by the polishing platen and the polishing head portion. . Further, the polishing method may improve or improve the flatness of the polishing object by supplying a cooling fluid to a portion of the polishing object while lowering the temperature of the edge region of the polishing object while the polishing object is polished by the polishing platen and the polishing head portion. have.

Description

Polishing Apparatus and Polishing Method {POLISHING APPARATUS AND POLISHING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing a polishing object and a polishing method using the same, and more particularly, to a polishing apparatus and a polishing method capable of improving the flatness of an edge of a polishing object to increase the yield of a semiconductor device. .

Generally, the polishing object used in the semiconductor is manufactured through a series of shaping processes such as lapping, etching, and grinding, and double-side polishing, final polishing, and cleaning. In particular, due to the high integration of semiconductor devices, scratches or defects applied to the polishing object during the chemical mechanical polishing (CMP) process of semiconductor manufacturing processes are recognized as one of important factors that greatly affect the yield and productivity of the devices. have. In particular, in the recent manufacturing process of semiconductor devices using large-diameter polishing objects (eg, 300 mm diameter), the polishing objects, polishing heads, and polishing pads are also increasing in size. For these reasons, the stress and impact applied to the surface of the polishing object during the polishing process is increasing, and as a result, the frequency of scratches or defects on the polishing object tends to be increased.

A polishing apparatus for performing the conventional CMP process includes a polishing plate and a polishing head for fixing an object to be polished. The polishing operation is performed while a slurry, which is a polishing agent, is supplied between the polishing table and the polishing head. Here, the polishing head can rotate on the polishing table after fixing the polishing object. At this time, the object to be polished may be polished while maintaining the contact and pressurized state to the polishing surface. Here, the flatness of the polishing object may vary according to the pressure distribution applied by the polishing head to the entire surface of the polishing object.

The object to be polished can be divided into a center portion and an edge portion in plan view. When the object is polished, a higher pressure may be applied to the edge portion than the center portion of the object to be polished. The problem may be worse than the flatness of. This unevenness of flatness can be a major variable that lowers the yield of semiconductor devices.

The present invention provides a polishing apparatus and a polishing method capable of improving or improving the flatness of a polishing target by improving polishing efficiency.

The present invention provides a polishing apparatus and a polishing method which are simple in production and have improved productivity and reliability.

According to one embodiment of the present invention, a polishing apparatus for polishing a polishing object, comprising: a polishing plate; A membrane positioned above the polishing plate to adjust the pressure applied to the polishing object, a backing film temporarily fixing the polishing object to the lower portion of the membrane, and provided around the polishing object to provide the polishing object together with the backing film. A holding head for supporting and fixing the polishing head, the polishing head portion moving up and down with respect to the polishing platen and polishing the polishing object; And a cooling unit provided inside the membrane and supplying a cooling fluid to the edge region of the polishing object to cool the edge region. The cooling rate of the edge region may be slowed by the cooling unit.

In general, when a polishing object is polished, relatively high pressure is applied to the edge region of the polishing object, and as a result, the temperature of the edge region can be partially raised. In general, when the temperature of the polishing object is increased, the polishing object may be excessively polished. As described above, when the temperature of the edge region is partially increased in the polishing object, the edge region is excessively polished, so that the entire surface of the polishing object is flat. The degree may drop.

Therefore, in the present invention, a cooling unit capable of partially cooling the polishing object is provided, and the cooling unit may be provided to provide or circulate a cooling fluid into the polishing head portion to partially control the temperature of the polishing object. Preferably, the cooling unit may provide the cooling fluid to pass adjacent the edge region of the polishing object. That is, the cooling unit may lower the polishing rate of the edge region by locally lowering the temperature of the edge region in the polishing object, and may improve the flatness of the polishing object.

Here, the cooling fluid provided by the cooling unit may be provided in a liquid state corresponding to water or water, and in some cases, may be provided in a gaseous state. Further, it may be preferably used for cooling the edge region of the polishing object, but may be selectively provided to other specific regions of the polishing object depending on the desired conditions even if not the edge region.

The cooling unit may include a cooling body capable of guiding the cooling fluid inside the polishing head portion and a cooling inlet path for supplying the cooling fluid to the cooling body. In other words, the cooling unit may be supplied with cooling fluid along the edge region of the polishing object through the cooling body, and the cooling body may be formed in a tubular shape along the outer surface of the polishing object, for example. In addition, the cooling inflow path serves to supply the cooling fluid from the outside to the cooling body, and in general, after lowering the temperature of the cooling inflow path to which the cooling fluid that can lower the temperature of the edge region and the edge region of the polishing object It may be provided as a cooling inlet path for discharging the cooling fluid having an elevated temperature to the outside.

The cooling inlet may connect the external cooling fluid supply unit and the cooling body inside the head in various structures and manners. For example, it may be connected to the outside by forming a hole in the outer portion of the polishing head portion, but may be connected to the outside through the inside of the head or the shaft. Although the present invention describes that the cooling inflow path is provided at the outer side of the polishing head portion, it is also possible to provide a different case.

The present invention also provides a polishing method for polishing a polishing object, comprising: providing a polishing plate; A membrane for controlling the pressure applied to the polishing object on the polishing surface, a backing film for temporarily fixing the polishing object to the lower portion of the membrane, and a peripheral portion provided to support the polishing object together with the backing film. Providing a polishing head portion having a retaining ring to fix the polishing head and moving up and down with respect to the polishing platen to polish the polishing object; Providing a polishing object to the bottom of the polishing head portion; Polishing the polishing object while the polishing platen and the polishing head portion move relatively; And cooling the edge region by supplying a cooling fluid to the inside of the membrane to correspond to the edge region of the object to be polished, wherein the polishing speed of the edge region may be slowed down by cooling the edge region. .

In the cooling of a part of the polishing object, a cooling fluid may be provided to the polishing object, for example, the cooling fluid may be provided along an edge region of the polishing object. In other words, since the temperature of the edge region of the polishing object may be locally increased when the polishing object is polished, a cooling fluid for lowering the temperature of the edge region in the process of polishing the polishing object may be provided. The edge region of the polishing object to which the cooling fluid is provided may be formed at a relatively low temperature to reduce the polishing rate, and prevent the edge region from being excessively polished to improve or improve the flatness of the polishing object as a whole.

A cooling unit may be provided in the polishing head unit to provide a cooling fluid to the polishing object, and water may be generally used as the cooling fluid provided in the cooling unit, but a fluid having a high heat capacity may be used even if it is not water. .

In addition, the cooling fluid may be provided along the edge region of the polishing object in the cooling of a part of the polishing object, and may be provided through the cooling body. The cooling body may be formed in a tubular shape provided along the edge region of the object to be polished, thereby lowering the temperature of the edge region of the object to be polished.

The polishing apparatus and polishing method of the present invention can improve or improve the flatness of the polishing target by improving the polishing efficiency. In addition, since the flatness of the polishing object is improved, the productivity of the polishing object can be further improved.

In addition, the polishing apparatus and the polishing method of the present invention may be easy to polish the polishing object because the manufacturing is simple. Productivity and reliability can be improved because time and manpower for polishing the polishing object can be saved.

1 is a cross-sectional view showing the polishing apparatus of the present invention.

2 is a cross-sectional view illustrating the polishing head of FIG. 1.

3 is an enlarged cross-sectional view illustrating a region II of FIG. 2.

4 is an exploded perspective view showing the relationship between the cooling unit and the polishing object.

5 is a graph showing the polishing rate of the polishing object with temperature using the polishing apparatus of the present invention.

6 is a flowchart illustrating a method of polishing an object to be polished using the polishing apparatus of the present invention.

<Explanation of symbols for main parts of the drawings>

100: polishing apparatus 140: polishing head portion

142: polishing object 152: cooling body

154: cooling inlet 150: cooling unit

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. For reference, in the present description, the same numbers refer to substantially the same elements, and may be described by quoting the contents described in other drawings under the above rules, and the contents repeated or deemed apparent to those skilled in the art may be omitted.

1 is a cross-sectional view showing a polishing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the polishing apparatus 100 includes a polishing plate 160, a polishing head 140, and a cooling unit 150. The polishing plate 160 is provided with a polishing pad 162 for polishing, and a polishing object 142 such as a wafer may be temporarily fixed to the polishing head 140. The cooling unit 150 may be accommodated in the polishing head 140 and partially cool the temporarily fixed polishing object 142.

The polishing plate 160 supports the polishing pad 162 and may polish the polishing object 142 while moving relative to the polishing head portion. At this time, the polishing pad 162 may rotate the polishing object 142 while rotating in an arbitrary direction and speed. Although the polishing head 140 is fixed and the polishing surface 160 is rotated, the polishing object 142 may be polished. However, in some cases, the polishing surface is fixed or the polishing head and the polishing surface rotate together to polish the polishing object. You can do it. In this case, the polishing pad 162 may include a polishing surface for polishing the surface of the polishing object 142, and the polishing surface may include grooves having various shapes to increase polishing efficiency of the polishing object 142. Can be formed.

The polishing head unit 140 may be positioned above the polishing plate 160 and move up and down to position the polishing object 142 on the polishing pad 162. The polishing object 142 may be mounted below the polishing head 140, and a surface to be polished of the polishing object 142 may be mounted to face the polishing pad 162.

For reference, in the present embodiment, the polishing head portion is provided in a substantially flat cylindrical shape, but in some cases, the polishing head portion may be provided in various shapes such as a conical shape and a conical column shape. It may be provided in a shape.

The polishing head 140 includes a membrane housing 145, a membrane 144, a backing film 143, and a retaining ring 141. The membrane 144 may be formed using an elastic material, and adjust the pressure applied to the polishing object 142 while expanding or contracting in the membrane housing 145. The membrane housing 145 may generally be formed of a material such as stainless steel (SUS), but in some cases, may be formed of a reinforced plastics-based material, a ceramic-based material, or the like.

The backing film 143 is provided under the membrane 144, and the backing film 143 may temporarily fix the polishing object 142 to the lower portion of the polishing head 140 by using surface tension or other adhesive force of water. have. The backing film 143 may be formed using a polyurethane material or the like.

In addition, a retaining ring 141 may be provided around the object to be polished to closely contact the area of the object to be polished. Only the surface tension of the backing film 143 may not sufficiently fix the polishing object 142, and the retaining ring 141 may assist this. The retaining ring 141 may prevent the polishing object 142 from being separated and prevent the polishing pad 162 from curling during polishing. In addition, since the retaining ring 141 is located around the polishing object 142, the pressure concentrated in the edge region of the polishing object 142 can be dispersed.

Here, the polishing object 142 may be provided as a general wafer used in a semiconductor process, and the polishing object 142 of the present invention is described with an example of a wafer, but the present invention is not limited thereto or limited thereto.

The polishing head unit 140 may include a cooling unit 150 provided along an edge area of the polishing object 142. The cooling unit 150 serves to prevent the temperature of the edge region of the polishing object 142 from rising when the polishing object 142 is polished by the polishing pad 162.

For example, the membrane 144 in the polishing head 140 serves to apply a uniform pressure to the polishing object 142. Due to the pressure formed by the membrane 144 and the pressure formed when the polishing object 142 is polished, a high pressure may occur in the edge region of the polishing object 142. Due to the high pressure, the temperature of the edge region of the polishing object 142 may increase, and excessive polishing may occur in the edge region of the polishing object 142 having the elevated temperature. In order to prevent this, the cooling unit 150 may be mainly provided in the edge region of the polishing object 142.

2 is a cross-sectional view showing the polishing head portion of FIG. 1, FIG. 3 is an enlarged cross-sectional view showing a region II of FIG. 2, and FIG. 4 is an exploded perspective view showing the relationship between the cooling portion and the polishing object.

2 to 4, as described above, the polishing head portion 140 includes a membrane housing 145, a membrane 144, a backing film 143, and a retaining ring 141. . The membrane housing 145 may include an air flow path for guiding the inflow and outflow of air to the membrane 144, and an axial drive unit capable of rotating and linear movement may be coupled to the upper side of the main body.

Membrane 144 may be expanded or contracted by the air entering and exiting. When the air stored in the membrane housing 145 is discharged, the pressure inside the membrane 144 is lowered, and the polishing object 142 may be mounted under the membrane 144 due to the pressure difference. In contrast, when the polishing object 142 is positioned on the polishing pad 162 and is to be polished, air may be introduced into the membrane housing 145 to expand the membrane 144. The object to be polished 142 may be pushed toward the polishing plate 160 by the expanded membrane 144 to be in close contact with the polishing pad 162.

The membrane housing 145 may be positioned outside the membrane 144 to receive the membrane 144, and may support the membrane 144 to adjust the pressure applied to the polishing object 142 by the membrane 144. In addition, the membrane housing 145 is the abrasive object 142 at the polishing head 140 when it is expanded or contracted by the air flowing from the membrane housing 145 by pressing the membrane 144 toward the polishing plate 160. This can be prevented from separating.

The cooling unit 150 may be provided inside the membrane 144. The cooling unit 150 may generally be formed along the inside of the membrane 144, and may be preferably formed along its edge area on the object to be polished 142. As shown in FIG. 3 and FIG. 4, the cooling unit 150 may be formed throughout the edge region of the polishing object 142, and the range in which the cooling unit 150 is provided in the polishing object 142 is It may be provided with a change in accordance with the conditions, design specifications, etc. required by the invention.

In addition, the cooling unit 150 may be provided to be changed according to the shape of the polishing object 142. As shown in FIG. 4, when the polishing object 142 is formed in a circular shape, the cooling unit 150 may be provided along the edge region of the polishing object 142. In other words, since the cooling unit 150 may supply a cooling fluid to be described later to lower the temperature of the edge region, the cooling unit 150 may be formed in a circular tubular shape along the region where the cooling fluid is supplied. However, the shape of the cooling unit 150 may be changed and provided according to conditions, design specifications, and the like required by the present invention.

The cooling fluid supplied by the cooling unit 150 may lower the temperature of the edge region of the object to be polished 142. That is, the cooling unit may lower the polishing rate of the edge region by locally lowering the temperature of the edge region in the polishing object, and may improve the flatness of the polishing object. This can be seen in the graph below.

5 is a graph for explaining a polishing rate of a polishing object with temperature.

Referring to FIG. 5, it can be seen that the polishing rate increases as the temperature of the wafer increases. When the wafer temperature is about 10 ° C., the polishing rate of the wafer is about 0.49 μm / min at maximum, whereas when the wafer temperature is about 20 ° C. under the same conditions, the polishing rate of the wafer increases to about 0.54 μm / min. When the wafer temperature is about 30 ° C., it can be seen that the polishing rate of the wafer increases to about 0.56 to 0.60 μm / min.

Therefore, as the temperature of the edge region increases in the object to be polished, the polishing rate in the edge region increases, and under the same conditions, the edge region may be polished faster than the center portion.

However, as shown in FIGS. 1 to 4, when the cooling unit 150 is provided in the edge region, the temperature rise in the edge region may be prevented, and as a result, a uniform polishing rate of the entire object 142 may be uniform. It can be made to be polished with. Here, the fluid temperature, the fluid movement amount, etc. using the cooling unit may be determined to be optimal values through experiments.

Cooling fluid may be provided along the cooling unit 150 to lower the temperature of the edge region of the polishing object 142. Here, the cooling fluid may be generally provided as water, but the heat capacity is high so as to lower the temperature of the edge region of the polishing object 142, and may be provided as various fluids that may be provided along the cooling unit 150. It is not limited or limited to the present invention depending on the type of cooling fluid.

In addition, the cooling unit 150 may provide a cooling body 152 to which a cooling fluid is supplied. The cooling body 152 may be provided inside the cooling unit 150, and may be provided along an edge region of the object to be polished 142. In addition to this, the cooling body may be formed in various ways, such as being provided in a spiral wound shape.

The cooling unit 150 may further include a cooling inflow path 154 that may supply a cooling fluid to the cooling body 152 from the outside. In the drawing, the cooling inflow path 154 is connected to the upper portion of the cooling body and exposed to the outside of the polishing head 140, but may be connected to the outside through the inside of the membrane, or may be connected to the outside through the shaft drive unit.

The cooling inlet 154 may be provided on the cooling body 152 such that cooling fluid is provided along an edge region of the polishing head 140 polishing object 142. The cooling fluid supplied through the cooling inflow path 154 may flow along the edge region of the object to be polished 142 within the cooling body 152. One of the two cooling inlets 154 may be used to supply the cooling fluid and the other to discharge the cooling fluid.

6 is a flowchart illustrating a method of polishing a polishing object using the polishing apparatus of the present invention.

Referring to FIG. 6, a step of providing a polishing table and a polishing head part (S601), a step of providing a polishing object to the bottom of the polishing head part (S602), and a step of relatively moving the polishing table and the polishing head part to be relatively polished. (S603) and cooling (S604) a part of the polishing object.

In the step of providing the polishing plate and the polishing head portion (S601) and the step of providing the polishing object to the bottom of the polishing head portion (S602), the polishing object 142 may be mounted on the polishing head portion 140, and the polishing object 142 ) May be mounted to the bottom in the direction to be polished. Here, the polishing plate 160 may be mounted to face the polished surface of the polishing object 142 mounted on the polishing head unit 140.

When the polishing object 142 is mounted on the polishing head 140, the polishing surface and the polishing head may be relatively moved to perform the polishing of the polishing object (S603). At this time, during the polishing of the polishing object while the polishing plate and the polishing head are relatively moved (S603), cooling of a part of the polishing object (S604) may be performed together.

In other words, when the polishing object 142 is polished by the relative movement of the polishing plate 160 and the polishing head 140, the temperature of the edge region of the polishing object 142 may increase, and the temperature of the edge region may be increased. When is increased, the polishing rate is increased only in the edge region, thereby reducing the flatness of the polishing object 142 as a whole. In order to improve the flatness of the polishing object 142, it is necessary to lower the temperature of the edge region while the polishing object 142 is being polished. For this purpose, a cooling fluid may be selectively supplied only to a portion corresponding to the edge region.

Such cooling fluid is generally provided as water, but alternatively a fluid having a high heat capacity and capable of lowering the temperature of the edge region of the object to be polished 142 may be provided.

In the step S604 of cooling a part of the polishing object, the cooling fluid may be guided to the cooling body 152, and the cooling fluid may be supplied and discharged through the cooling inflow path 154 to supply the cooling fluid guided to the cooling body 152. Can be. In this case, the cooling body 152 may be provided along the edge region to lower the temperature of the edge region of the object to be polished 142. The cooling body is preferably provided along the edge region to which the cooling fluid is supplied, but the present invention is not limited or limited by the shape of the cooling body provided.

Here, the cooling fluid may be supplied to the cooling body 152 through the cooling inflow path 154 to pass through the edge region of the polishing object 142 adjacently. The cooling inlet 154 serves to supply the cooling fluid from the outside, and the temperature is increased after lowering the temperature of the inlet and the edge region to which the cooling fluid is supplied, which is provided in at least one pair to lower the temperature of the edge region. It can be used as an outlet for discharging the cooled cooling fluid to the outside. The cooling inflow path 154 may be formed at the outer side or the central portion of the polishing head portion 140, and is formed to be close to the outer portion of the polishing head portion 140 so that the cooling fluid can be easily supplied to the edge region. something to do.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (10)

In the polishing apparatus for polishing a polishing object, Polishing plate; A membrane positioned above the polishing plate to adjust the pressure applied to the polishing object, a backing film temporarily fixing the polishing object to the lower portion of the membrane, and provided around the polishing object to provide the polishing object together with the backing film. A holding head for supporting and fixing the polishing head, the polishing head portion moving up and down with respect to the polishing platen and polishing the polishing object; And And a cooling unit provided inside the membrane and supplying a cooling fluid to the edge region of the polishing object to cool the edge region. And the cooling unit slows down the polishing rate of the edge region. delete The method of claim 1, And the cooling fluid comprises water or a relatively high heat capacity fluid. The method of claim 1, The cooling unit includes a cooling body for guiding the cooling fluid inside the polishing head part and a cooling inlet path for supplying the cooling fluid to the cooling body. And the cooling body is provided along the edge region of the polishing object. The method of claim 4, wherein And the cooling inflow path is formed at an outer side portion or a central portion of the polishing head portion. In the polishing method of polishing a polishing object, Providing a polishing plate; A membrane for controlling the pressure applied to the polishing object on the polishing surface, a backing film for temporarily fixing the polishing object to the lower portion of the membrane, and a peripheral portion provided to support the polishing object together with the backing film. Providing a polishing head portion having a retaining ring to fix the polishing head and moving up and down with respect to the polishing platen to polish the polishing object; Providing a polishing object to the bottom of the polishing head portion; Polishing the polishing object while the polishing platen and the polishing head portion move relatively; And And cooling the edge region by supplying a cooling fluid to the inside of the membrane so as to correspond to the edge region of the object to be polished. Cooling the edge region slows the polishing rate of the edge region. delete The method of claim 6, And the cooling fluid comprises water or a relatively high heat capacity fluid. The method of claim 6, And a cooling body for guiding the cooling fluid in the step of cooling the edge region and a cooling inlet passage for supplying the cooling fluid to the cooling body. The method of claim 9, And the cooling inlet is formed at an outer side portion or a central portion of the polishing head portion.