KR102257834B1 - Polishing pad with depth adjustable grooves and polishing apparatus comprising the same - Google Patents

Abstract

In the polishing pad according to an embodiment, the depth of the groove can be adjusted by introducing an elastic body to the bottom surface of the groove, so that the actual depth of the groove can be kept constant even after the conditioning process. Therefore, the polishing pad and the polishing apparatus including the same according to the embodiment can prevent a decrease in slurry fluidity due to a decrease in groove depth during a conventional CMP process, and as a result, improve the polishing performance and reduce the occurrence of defects such as scratches, It is possible to increase the life of the polishing pad.

Description

A polishing pad having a groove that can be adjusted in depth, and a polishing device including the same {POLISHING PAD WITH DEPTH ADJUSTABLE GROOVES AND POLISHING APPARATUS COMPRISING THE SAME}

The embodiment relates to a polishing pad having a groove capable of adjusting the depth and a polishing apparatus including the same. More specifically, embodiments relate to a polishing pad capable of adjusting the depth of a groove in a chemical mechanical polishing (CMP) process, a polishing apparatus including the same, and a method of manufacturing a semiconductor device using the same.

In the chemical mechanical polishing (CMP) process of the semiconductor manufacturing process, a semiconductor substrate such as a wafer is attached to a head and a slurry is supplied to the semiconductor substrate surface in a state in which it is brought into contact with the surface of a polishing pad formed on a platen. It is a process of mechanically flattening the irregularities on the surface of the semiconductor substrate by reacting with the surface plate and the head.

The polishing pad is an essential material that plays an important role in such a CMP process, and is generally made of a polyurethane-based resin, and a groove that takes charge of a large flow of slurry on the surface and pores that support fine flow. ).

The groove may have various shapes, for example, there are grooves such as a circle that share a center (refer to Korean Patent Laid-Open No. 2005-95818). In this way, the grooves provided in the polishing pad serve to assist in polishing the surface of the semiconductor substrate by flowing while carrying the slurry.

The pores are formed using a solid foam having voids, a liquid material that generates gas by a chemical reaction, or an inert gas, and are formed as open pores on the surface of the polishing pad to support fine flow of the slurry and enhance polishing performance. Plays a role. In addition, the pores are deformed by compressive force and shear force applied in the CMP process or carry foreign substances.In order to recover from the gradual deterioration of the surface condition of the polishing pad during the CMP process by this process, the polishing layer is It is also performing a conditioning process that cuts the surface.

Republic of Korea Patent Publication No. 2005-95818

In the conventional polishing pad, since the groove is fixedly formed on the polishing layer through processing such as molding or milling, the thickness of the polishing layer gradually decreases through the conditioning process in the CMP process and the depth of the groove decreases. In this way, as the depth of the groove decreases during the CMP process, the flow of the slurry by the groove is inhibited. As a result, the polishing performance is impaired, the occurrence of defects such as scratches is increased, and the life of the polishing pad is shortened.

Accordingly, as a result of research by the present inventors, it is possible to adjust the depth of the groove by introducing an elastic body to the bottom surface of the groove, so that even if the thickness of the polishing layer is reduced by the conditioning process, it is possible to maintain a constant depth of the groove. I found it.

Accordingly, an object of the embodiment is to provide a polishing pad having a groove capable of adjusting the depth, a polishing apparatus, and a method of manufacturing a semiconductor device using the same.

According to one embodiment, a polishing layer having a plurality of grooves; A support layer disposed under the polishing layer and having a plurality of empty spaces corresponding to the respective grooves; And an elastic coating layer disposed between the polishing layer and the support layer and constituting a bottom surface of the groove.

According to another embodiment, the platen; A polishing pad according to the embodiment disposed on the base plate; And a pneumatic pressure regulating pump that expands or contracts the elastic coating layer by applying air pressure or vacuum to the empty space of the support layer of the polishing pad.

According to another embodiment, the step of polishing the surface of the semiconductor substrate using the polishing apparatus according to the embodiment; And adjusting the position of the bottom surface of the groove by applying air pressure or vacuum to the empty space of the support layer of the polishing pad by the pneumatic pressure control pump of the polishing apparatus.

The polishing pad according to the above embodiment makes it possible to adjust the depth of the groove by configuring the bottom surface of the groove with an elastic coating layer, so that even if the thickness of the polishing layer is reduced by the conditioning process, the actual depth of the groove can be maintained constant. have. In addition, adjusting the depth of the groove can be easily implemented by configuring the polishing apparatus to expand the elastic coating layer by forming a void in the surface plate to which the polishing pad is attached, and applying air pressure or vacuum therethrough.

Therefore, the polishing pad and polishing apparatus according to the above embodiment can prevent a decrease in slurry fluidity due to a decrease in groove depth during a conventional CMP process, and as a result, maintain a constant polishing performance and reduce the occurrence of defects such as scratches, and polishing. It can increase the life of the pad.

1 and 2 are plan views and cross-sectional views of a polishing pad according to an embodiment.
3 is a cross-sectional view illustrating a state in which an elastic coating layer is expanded in a downward direction in a polishing pad according to an embodiment.
4 to 6 are cross-sectional views of a polishing pad according to another embodiment.
7 and 8 are perspective views and cross-sectional views of a polishing apparatus according to an embodiment.
9 shows a void formed in the platen according to an embodiment.
10 illustrates a method of manufacturing a semiconductor device according to an embodiment.

In the description of the following embodiments, it is described that one component is formed above or below another component, in which one component is directly above or below another component, or indirectly through another component. It includes all that are formed by.

In the present specification, "including" a certain element means that other elements may not be excluded, and other elements may be further included, unless otherwise specified.

In addition, all numerical ranges representing physical property values, dimensions, and the like of the constituent elements described in the present specification are to be understood as being modified by the term "about" in all cases unless otherwise specified.

In the present specification, the singular expression is interpreted as meaning including the singular or plural, which is interpreted in context, unless otherwise specified.

[Polishing pad]

1 and 2 are plan views and cross-sectional views of a polishing pad according to an embodiment.

1 and 2, a polishing pad 10 according to an embodiment includes a polishing layer 100 having a plurality of grooves 110; A support layer 200 disposed under the polishing layer 100 and having a plurality of empty spaces 210 corresponding to the respective grooves 110; And an elastic coating layer 300 disposed between the polishing layer 100 and the support layer 200 and constituting the bottom surface of the groove 110.

In addition, the polishing pad 10 may further include a microchannel layer 400 disposed inside the individual grooves 110 and having a plurality of microchannels.

Hereinafter, each component of the polishing pad according to the embodiment will be described in detail.

Polishing layer

The polishing layer is polished by facing the semiconductor substrate in a polishing process.

The thickness of the polishing layer is not particularly limited. Specifically, the average thickness of the polishing layer may be 0.8 mm to 5.0 mm, 1.0 mm to 4.0 mm, 1.0 mm to 3.0 mm, 1.5 mm to 2.5 mm, 1.7 mm to 2.3 mm, or 2.0 mm to 3.5 mm.

The polishing layer has a plurality of grooves. The groove can increase polishing efficiency by controlling the fluidity of the slurry used in the CMP process.

The groove may have a circular shape that shares a center. Specifically, the cross section of the groove in the planar direction of the polishing layer may have a shape of a circle, more specifically, a shape of a circumference of a circle or a hollow circle. However, the shape of the groove is not particularly limited, and may have, for example, a shape of a geometric figure (polygon, etc.) sharing a center.

The spacing between the grooves in the polishing layer is not particularly limited, but, for example, the pitch spacing of the grooves may be 1 mm to 10 mm, 1 mm to 5 mm, or 2 mm to 4 mm. The pitch spacing of the grooves may mean a linear distance between the midpoints of the bottom surface of each groove in any two grooves.

Referring to FIG. 2, when viewed from a cross section of the polishing layer 100, the groove 110 may penetrate the polishing layer 100 in the thickness direction. Accordingly, the depth d of the groove 110 may be the same as the thickness t1 of the polishing layer 100.

Specifically, the depth of the groove may be 0.4 mm to 5.0 mm, 0.5 mm to 4.0 mm, 0.6 mm to 3.0 mm, 0.7 mm to 2.5 mm, 0.8 mm to 2.3 mm, or 0.9 mm to 3.5 mm. In addition, the width of the groove may be 0.2 mm to 2 mm, 0.2 mm to 1 mm, or 0.2 mm to 0.6 mm.

The groove may be formed in the polishing layer through a processing method such as molding or milling.

The polishing layer may include a urethane-based polymer. The urethane-based polymer may be formed by a curing reaction between a urethane-based prepolymer and a curing agent. For example, the polishing layer may be prepared from a composition containing a urethane-based prepolymer, a curing agent, a foaming agent, and other additives.

Accordingly, the polishing layer may include a urethane-based polymer prepared from a composition including a urethane-based prepolymer, a curing agent, a foaming agent, and other additives. The prepolymer generally refers to a polymer having a relatively low molecular weight in which the degree of polymerization is stopped in an intermediate step to facilitate molding of the final product. The prepolymer can be molded on its own or after reaction with other polymerizable compounds. Specifically, the urethane-based prepolymer is prepared by reacting an isocyanate compound and a polyol, and may include an unreacted isocyanate group (NCO). The isocyanate compound and the polyol compound are not particularly limited as long as they can be used in the production of a urethane-based polymer.

The curing agent may be one or more of an amine compound and an alcohol compound. Specifically, the curing agent may include one or more compounds selected from the group consisting of aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

The foaming agent is not particularly limited as long as it is commonly used to form pores of the polishing pad. For example, the foaming agent may be at least one selected from a solid foaming agent having a hollow structure, a liquid foaming agent using a volatile liquid, and an inert gas.

The polishing layer may have a porous structure including pores. The average diameter of the pores may be 5 μm to 200 μm. The polishing layer may include pores of 10% by volume to 70% by volume with respect to the total volume of the polishing layer. Specifically, the porosity of the polishing layer may be 20% to 70% by volume. The pores may have a structure of an open cell or a closed cell. For example, the polishing layer may have open cell pores on the polishing surface and closed cell pores inside the polishing layer.

Micro-channel layer

The polishing pad may further include a microchannel layer disposed inside the individual grooves and having a plurality of microchannels.

The micro-channel layer serves to support the polishing layer between the polishing layer and the elastic coating layer, and has a micro flow channel so that the slurry can flow well over the elastic coating layer.

The microchannel layer may be formed only inside the groove, or may be formed inside the groove and in other regions. As an example, as shown in FIG. 2, the microchannel layer 400 may be formed only inside the groove 110. As another example, as shown in FIG. 4, the micro-channel layer 400 may be formed in the groove 110 and in a partial lower region of the polishing layer.

The thickness of the microchannel layer may be 0.1 mm to 5 mm, 0.5 mm to 4 mm, 0.5 mm to 3 mm, 0.5 mm to 2.5 mm, or 0.5 mm to 2 mm.

Referring to FIG. 2, it is advantageous in terms of slurry flow that the thickness t2 of the microchannel layer is smaller than the depth d of the groove. For example, the microchannel layer may have a thickness of 70% or less, or 50% or less of the depth of the groove. Specifically, the microchannel layer may have a thickness of 30% or less compared to the depth of the groove. For example, the microchannel layer may have a thickness of 10% to 50%, or 10% to 30% of the depth of the groove.

It is preferable that the microchannel layer has an impact strength equal to or higher than that of the polishing layer. For example, the microchannel layer may have a notched Izod Impact strength (ASTM D256, 73°F) of 0.31 ft·lb/in to 1.1 ft·lb/in.

The micro-channel of the micro-channel layer may be designed in consideration of the fluidity of the slurry. For example, the microchannels of the microchannel layer may be formed in a network structure. The structure of the microchannel is not limited in its shape as long as it does not interfere with the fluidity of the slurry.

In addition, the inner diameter of the microchannel may be designed so that the slurry can easily pass. For example, the inner diameter of the microchannel may be 0.1 mm to 5 mm, 0.1 mm to 3 mm, 0.1 mm to 2 mm, 0.5 mm to 2 mm, 0.1 mm to 1 mm, or 1 mm to 3 mm. Specifically, the microchannel may have an inner diameter of 0.1 mm to 2 mm.

The method of forming the microchannel layer on the polishing pad is not particularly limited. As an example, a groove may be formed only in an upper region of the polishing layer by molding or milling, and a plurality of fine passages may be directly formed in the lower region of the groove to fabricate the fine passage layer.

As another example, after forming a groove to penetrate the polishing layer in the thickness direction by molding or milling, and separately manufacturing a microchannel layer having a plurality of microchannels, the microchannel layer can be inserted into the groove. have. In this case, the microchannel layer may be separately manufactured using the same or similar material as the polishing layer.

Elastic coating layer

The elastic coating layer may expand or contract as necessary to substantially adjust the depth of the groove.

3 is a cross-sectional view illustrating a state in which an elastic coating layer is expanded in a downward direction in a polishing pad according to an embodiment. Referring to FIG. 3, the elastic coating layer 300 may expand in the empty space 210 of the support layer 200 to lower the position of the bottom surface of the groove 110. Specifically, compared to the position h2 of the bottom surface of the groove before the elastic coating layer 300 expands downward, the position h3 of the bottom surface after expansion is lowered. As a result, the difference from the position h1 of the surface of the polishing layer to the position of the bottom surface of the groove may be greater after the expansion than before. That is, the expansion of the elastic coating layer may increase a height difference from the surface of the polishing layer to the bottom surface of the groove.

The elastic recovery rate of the elastic coating layer may be 70% or more, 80% or more, 90% or more, 95% or more, or 97% or more.

For example, the elastic coating layer may include a rubber-based material, and specifically, natural rubber such as latex, styrene-butadiene rubber, polychloroprene rubber, acrylonitrile-butadiene rubber, isoprene-isobutylene rubber, butadiene rubber, It may include isoprene rubber, ethylene-propylene rubber, polysulfide rubber, silicone rubber, fluoro rubber, urethane rubber, acrylic rubber, etc.

The elastic coating layer may have a thickness of 10 μm to 200 μm. When it is within the above range, stiffness and dimensional stability of the elastic coating layer upon heating may be more excellent. More specifically, the thickness of the elastic coating layer may be 10 µm to 100 µm, or 15 µm to 55 µm.

Specifically, the elastic coating layer may include a rubber-based material having an elastic recovery rate of 90% or more, and may have a thickness of 10 μm to 200 μm.

In addition, the elastic coating layer may have a sealing force to prevent leakage or immersion between the polishing layer and the support layer.

Support layer

The support layer serves to absorb and disperse the impact applied to the polishing layer while supporting the polishing layer.

In addition, the support layer is disposed under the polishing layer and has a plurality of empty spaces corresponding to the individual grooves. Referring to FIG. 3, the empty space 210 of the support layer 200 provides a space in which the elastic coating layer 300 can expand downward.

Specifically, the empty space 210 may have a depth of 0.1 mm to 5.0 mm. When within the above range, expansion of the elastic coating layer is performed without difficulty without impairing the effect of the support layer supporting the polishing layer, which may be more advantageous. More specifically, the empty space may have a depth of 1.0 mm to 3.0 mm.

The empty space of the support layer may penetrate the support layer in a thickness direction, and accordingly, the depth of the empty space may be the same as the thickness of the support layer. In this case, the inflow and outflow of air into the empty space may be the most free. In addition, in order to reinforce the mechanical properties of the support layer, a structure may be inserted under the empty space. At this time, the inserted structure may be a porous structure having a plurality of voids so that air inflow and outflow into the empty space is smooth. 5 shows an example in which the porous structure 220 is inserted into the empty space 210 of the support layer 200.

Alternatively, the empty space of the support layer may be formed only in the upper region of the support layer, and in this case, a plurality of voids may be formed in the lower region of the support layer. At this time, the support layer may be manufactured using a material having a plurality of voids. 6 illustrates that the support layer 200 is made of a porous material, thereby providing a plurality of voids under the empty space 210.

The hardness of the support layer is smaller than that of the polishing layer, and even if the thickness of the polishing layer is thin, the polishing can be stably performed by preventing the polishing layer from floating or the surface of the polishing layer from being curved during polishing. For example, the hardness of the support layer may be 90% or less of the hardness of the polishing layer, and specifically 50% to 90%, 50% to 80%, or 50 to 70%. Specifically, the hardness of the support layer is preferably 25 to 100, more preferably 30 to 85, based on the Asuka-A type hardness. In addition, the hardness of the support layer may be measured according to JIS K6253-1997.

The planar shape of the support layer is not particularly limited, and may be the same as or different from the planar shape of the polishing layer. For example, the planar shape of the support layer may be circular or polygonal (square, etc.).

The thickness of the support layer is also not particularly limited, but may be, for example, 0.1 mm to 5 mm, or 0.5 mm to 2 mm.

[Polishing device]

7 and 8 are perspective views and cross-sectional views of a polishing apparatus according to an embodiment.

Referring to Figures 7 and 8, the polishing apparatus according to an embodiment, the base 20; A polishing pad 10 according to the embodiment disposed on the base 20; And an air pressure control pump 30 for expanding or contracting the elastic coating layer 300 by applying air pressure or vacuum to the empty space 210 of the support layer 200 of the polishing pad 10.

Hereinafter, each component of the polishing apparatus according to the embodiment will be described in detail.

Polishing pad

The polishing pad is disposed on the base.

The structure and characteristics of the polishing pad are as described in the polishing pad of the above embodiment. That is, the polishing pad includes a polishing layer having a plurality of grooves; A support layer disposed under the polishing layer and having a plurality of empty spaces corresponding to the respective grooves; And an elastic coating layer disposed between the polishing layer and the support layer and constituting a bottom surface of the groove.

In addition, an adhesive layer may be formed under the support layer to be firmly bonded to the surface plate.

Plate

The platen is attached to the polishing pad and serves to rotate while supporting the polishing pad.

The platen may have a plurality of voids connected to an empty space in the support layer. The shape of the void is not particularly limited as long as air can smoothly flow to the upper and lower portions of the base.

9 shows a void formed in the platen according to an embodiment. Referring to FIG. 9, the void 21 may have a shape extending in the thickness direction of the base plate 20.

Specifically, the void may have an elongated column shape and may penetrate the platen in the thickness direction. The inner diameter of the void may be 0.1 mm to 5 mm, 0.1 mm to 3 mm, 0.1 mm to 1 mm, 1 mm to 5 mm, or 0.5 mm to 2 mm.

Pneumatic control pump

The air pressure control pump expands or contracts the elastic coating layer by applying air pressure or vacuum to the empty space of the polishing pad.

The structure and operation method of the air pressure control pump are not particularly limited.

Referring to FIG. 8, the platen 20 has a plurality of voids 21, the air pressure control pump 30 is connected to the voids 21 of the platen 20, and the empty space 210 of the support layer Pneumatic pressure or vacuum for) may be applied through the voids 21 of the base plate 20.

For example, the air pressure regulating pump may lower the air pressure or form a vacuum, and such low air pressure or vacuum is transmitted to the empty space of the support layer through the pores of the surface plate, thereby moving the elastic coating layer back downward. Can inflate.

In addition, the air pressure control pump may increase the air pressure, and such high air pressure may be transmitted to the empty space of the support layer through the pores of the surface plate, so that the elastic coating layer expanded in the lower direction may be contracted again.

[Semiconductor device manufacturing method]

A method of manufacturing a semiconductor device according to an embodiment includes: polishing a surface of a semiconductor substrate by using the polishing apparatus according to the embodiment; And adjusting the position of the bottom surface of the groove by applying air pressure or vacuum to the empty space of the polishing pad by the air pressure adjusting pump of the polishing apparatus.

In addition, the method of manufacturing the semiconductor device may further include conditioning by cutting the surface of the polishing layer in the polishing apparatus.

Polishing step of semiconductor substrate

In this step, the surface of the semiconductor substrate is polished using a polishing device.

10 illustrates a method of manufacturing a semiconductor device according to an embodiment. Referring to FIG. 10, the polishing of the semiconductor substrate 2 may be performed by a CMP process using a polishing slurry 3. Therefore, the polishing slurry 3 is sprayed onto the polishing pad 10 for polishing, and the semiconductor substrate 2 and the polishing pad 10 rotate relative to each other, so that the surface of the semiconductor substrate 2 is polished. Can be

Conditioning steps

In this step, conditioning of cutting the surface of the polishing layer in the polishing apparatus is performed.

Referring to FIG. 10, the surface cutting of the polishing layer may be performed using a conditioner 4 such as a diamond disk, but is not particularly limited.

The conditioning step may be performed simultaneously with the polishing step.

By cutting the surface of the polishing layer whose performance has deteriorated through such conditioning, the surface condition of the polishing pad is restored and the CMP performance can be maintained constant.

Steps for adjusting the position of the bottom surface of the groove

In this step, the position of the bottom surface of the groove is adjusted by applying air pressure or vacuum to the empty space of the polishing pad by the air pressure adjusting pump of the polishing apparatus.

In the conditioning step, the height difference from the surface of the polishing layer to the bottom surface of the groove is reduced, and the height difference from the surface of the polishing layer to the bottom surface of the groove in the step of adjusting the position of the bottom surface of the groove Can be recovered.

As an example, the polishing step, the conditioning step, and the step of adjusting the position of the bottom surface of the groove may all be performed simultaneously. Accordingly, it is possible to recover from the deterioration of the surface condition during the polishing process through the conditioning step, and in response to the gradually decreasing thickness of the polishing layer in the conditioning step, the position of the bottom surface of the groove is adjusted. You can keep the depth constant. As a result, it is possible to prevent a decrease in slurry fluidity due to a decrease in groove depth during a conventional CMP process, and as a result, it is possible to keep the polishing performance constant, reduce the occurrence of defects such as scratches, and increase the life of the polishing pad.

1: polishing apparatus, 2: semiconductor substrate, 3: polishing slurry,
4: conditioner, 10: polishing pad, 20: platen,
21: void, 100: polishing layer, 110: groove,
200: support layer, 210: empty space, 300: elastic coating layer,
400: micro-channel layer, A1-A1': cutting line.

Claims (14)

A polishing layer having a plurality of grooves;
A support layer disposed under the polishing layer, comprising: a support layer having a plurality of empty spaces corresponding to each of the plurality of grooves; And
A polishing pad comprising; an elastic coating layer disposed between the polishing layer and the support layer to form a bottom surface of the plurality of grooves, and including a rubber-based material to adjust the depth of the plurality of grooves as they expand or contract. .
The method of claim 1,
The polishing pad, wherein the elastic coating layer expands within the empty space of the support layer to lower the position of the bottom surface of the groove.
The method of claim 2,
The polishing pad, wherein the expansion of the elastic coating layer increases a height difference from the surface of the polishing layer to the bottom surface of the groove.
The method of claim 1,
The elastic coating layer,
A polishing pad comprising a rubber-based material having an elastic recovery rate of 90% or more and having a thickness of 10 µm to 200 µm.
The method of claim 1,
The polishing pad, wherein the groove has a depth equal to the thickness of the polishing layer.
The method of claim 1,
The polishing pad, wherein the empty space has a depth of 0.1 mm to 5.0 mm.
The method of claim 1,
The polishing pad,
A polishing pad further comprising a microchannel layer disposed inside each of the plurality of grooves and having a plurality of microchannels.
The method of claim 7,
The polishing pad, wherein the microchannel layer has a thickness of 30% or less compared to the depth of the groove.
The method of claim 7,
A polishing pad in which the microchannels of the microchannel layer are formed in a network structure.
The method of claim 7,
The polishing pad, wherein the microchannel has an inner diameter of 0.1 mm to 2 mm.
Platen;
The polishing pad of claim 1 disposed on the base plate; And
And a pneumatic pressure control pump for expanding or contracting the elastic coating layer by applying air pressure or vacuum to the empty space of the support layer of the polishing pad.
The method of claim 11,
The platen has a plurality of voids,
The pneumatic pressure control pump is connected to the void of the platen,
A polishing apparatus, wherein air pressure or vacuum to the empty space of the support layer is applied through the voids of the base.
Polishing the surface of the semiconductor substrate using the polishing apparatus of claim 11; And
And adjusting the position of the bottom surface of the groove by applying air pressure or vacuum to the empty space of the support layer of the polishing pad by the pneumatic pressure control pump of the polishing apparatus.
The method of claim 13,
The method of manufacturing the semiconductor device further comprises the step of cutting and conditioning the surface of the polishing layer in the polishing apparatus,
In the conditioning step, the difference in height from the surface of the polishing layer to the bottom surface of the groove is reduced,
In the step of adjusting the position of the bottom surface of the groove, the height difference from the surface of the polishing layer to the bottom surface of the groove is recovered.

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