KR101440175B1 - Polishing Pad and Method for Manufacturing The Same - Google Patents

Abstract

The present invention relates to a polishing pad exhibiting improved polishing efficiency by recycling at least a part of a polishing fluid and a method of manufacturing the same, wherein the polishing pad of the present invention comprises a polishing surface and a back surface located opposite to the polishing surface, And a plurality of grooves for the flow of the polishing fluid are formed on the back surface.

Description

Technical Field [0001] The present invention relates to a polishing pad,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad and a method of manufacturing the same, and more particularly, to a polishing pad and a method of manufacturing the same, more specifically, to a polishing method for polishing a silicon wafer for semiconductor manufacturing, ) Process and a method of manufacturing the same.

A polishing apparatus for planarization such as a silicon wafer includes a lower board having a circular rotary plate on which a polishing pad is mounted, an upper board for closely contacting the silicon wafer to the polishing pad, and a polishing fluid supply unit for supplying the polishing fluid to the polishing pad.

The polishing operation, which is a chemical-mechanical polishing, is an operation of pushing in a direction opposite to the polishing pad driving the wafer to remove the oxide including the deposited Si series and creating a very smooth and flat surface on the wafer, And / or a chemically active reagent is applied to the interface of the wafer and the polishing pad along with the polishing liquid.

Conventional polishing pads used for polishing do not have any artificially formed grooves (Japanese Patent Application Laid-Open No. 2006-043811) or have artificial grooves only on the polishing surface side (Korean Patent Laid-Open Publication No. 1996-7002787).

When such a polishing pad is used, there is a limit in improving the polishing efficiency.

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a polishing pad and a method of manufacturing the same that can prevent problems due to limitations and disadvantages of the related art.

One aspect of the present invention is to provide a polishing pad exhibiting improved polishing efficiency by recycling at least a part of the polishing fluid and a method of manufacturing the same.

Another aspect of the present invention is to provide a polishing pad and a manufacturing method thereof that can meet the polishing performance required by controlling the degree of recycling of the polishing fluid.

Further features and advantages of the invention will be described hereinafter, and will in part be obvious from the description. Alternatively, other features and advantages of the invention may be learned through practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS The objects and other advantages of the present invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

For one aspect of the present invention as above, a polishing surface; And a rear surface located on the opposite side of the polishing surface, wherein a plurality of grooves for the flow of the polishing fluid are formed on the back surface.

For another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: preparing an initial pad having a polishing surface and a back surface located opposite to the polishing surface; And forming a plurality of grooves for flow of the polishing fluid on the back surface of the polishing pad.

For another aspect of the present invention, there is provided a method comprising: preparing an auxiliary layer having a first side and a second side opposite to the first side; Forming a plurality of grooves for the flow of abrasive fluid on the second surface; And providing an abrasive layer on the first side of the auxiliary layer.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

According to the polishing pad of the present invention and the method of manufacturing the same, at least a part of the polishing fluid is recycled, so that it is possible to achieve a higher polishing rate than the conventional polishing pad, assuming that the same amount of polishing fluid is used, The amount of fluid used can be reduced.

In addition, according to the present invention, since the degree of recycling of the polishing fluid can be controlled through the flow control of the polishing fluid, various levels of polishing performance can be achieved in accordance with the purpose of the polishing process.

Other effects of the present invention will be described in more detail below with the related technical constructions.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Figure 1 shows the polishing fluid flow on the polishing surface as the polishing pad rotates,
2 shows a back surface of a polishing pad according to an embodiment of the present invention,
3 is a cross-sectional view along the grooves of the polishing pad according to an embodiment of the present invention,
Figure 4 shows the flow of polishing fluid as the polishing pad rotates in accordance with an embodiment of the present invention,
5 is a view for explaining a polishing fluid flow direction according to the present invention,
FIG. 6 is a cross-sectional view illustrating a method of manufacturing a polishing pad according to an embodiment of the present invention,
FIG. 7 is a cross-sectional view illustrating a polishing pad according to another embodiment of the present invention. Referring to FIG.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

The polishing rate of the polishing operation depends on the amount of polishing fluid used in the polishing operation. That is, as the amount of the polishing fluid supplied to the polishing surface increases, the polishing rate of the polishing operation also increases.

The present invention originates from the problem of the possibility of increasing the polishing rate of the polishing operation without changing the amount of the polishing fluid consumed during the polishing operation, and the present inventor has found that the polishing fluid provided on the polishing surface, The amount of polishing fluid actually used in the polishing operation can be increased without increasing the amount of the total polishing fluid consumed, and as a result, the polishing rate can also be improved.

In the case of a polishing pad in which grooves are not formed at all, it is impossible to recycle polishing fluid in that there is no means for controlling the flow of the polishing fluid. In the case of a polishing pad having grooves only on the polishing surface, it is also impossible to recycle the polishing fluid in that the grooves perform only the function of providing the discharge path of the polishing fluid and / or the polishing residue.

Therefore, a polishing pad of a new structure that enables the recycling of the used polishing fluid is required. Hereinafter, a polishing pad having such a structure and a manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings. do.

1 is a plan view for explaining the polishing fluid flow f1 on the polishing surface when the polishing pad 100 is rotated.

As shown in Fig. 1, during the polishing operation, the polishing pad 100 generally rotates counterclockwise, and the polishing fluid 10 is supplied onto the center of the polishing surface of the polishing pad 100. The centrifugal force and the inertial force due to the rotation of the polishing pad 100 are applied to the polishing fluid 10 supplied on the central portion of the polishing surface. As a result, the polishing fluid 10 is discharged from the polishing pad 100 after showing a spiral flow f1 from the central portion to the outer portion of the polishing surface as shown in Fig. The spiral flow f1 is in the form of a convex spiral in the direction of rotation of the polishing pad 100.

According to the present invention, at least a portion of the abrasive fluid 10 to be discharged from the polishing pad 100 can be recycled.

3 is a cross-sectional view along the groove 121 of the polishing pad 100 according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of the polishing pad 100 according to an embodiment of the present invention, Shows the flow of polishing fluid as the polishing pad 100 rotates according to an embodiment of the present invention.

As shown in Figs. 2 to 4, the polishing pad 100 of the present invention includes a polishing surface and a back surface located on the opposite side of the polishing surface.

The polishing pad 100 according to an embodiment of the present invention is a laminated structure including an auxiliary layer 120 and an abrasive layer 110 on the auxiliary layer 120 as shown in FIG. In this case, the upper surface of the polishing layer 110 serves as the polishing surface of the polishing pad 100, and the lower surface of the auxiliary layer 120 serves as the back surface of the polishing pad 100.

The conventional polishing layer has a structure composed of open pores or closed pores, but the polishing layer 110 according to the present invention is not particularly limited to any one structure. Meanwhile, the auxiliary layer 120 performs a buffering function during the polishing operation.

Alternatively, the polishing pad 100 of the present invention may have a single layer structure having a polishing surface and a back surface.

The polishing pad 100 is fixed to the surface plate 400 through an adhesive layer 300 made of a double-sided adhesive. Since the abrasive fluid is in contact with the adhesive layer 300 during the polishing operation, the adhesion between the polishing pad 100 and the adhesive layer 300 can be impaired. Therefore, in order to prevent the abrasion pad 100 from being peeled off by the polishing fluid, Layer 200 may be interposed.

On the back surface of the polishing pad 100, a plurality of grooves 121 for the flow of the polishing fluid are formed. Alternatively, the depth of the grooves 121 may be less than the thickness of the auxiliary layer 120, so that the grooves 121 may be formed only in the auxiliary layer 120.

The grooves 121 are configured to allow polishing fluid to flow from the outer side of the polishing pad 100 to the center along the grooves 121 as the polishing pad 100 rotates. More specifically, each of the grooves 121 is formed to extend from the central portion of the polishing pad 100 to the outer side, and is formed in a convex spiral shape in a direction opposite to the rotation direction of the polishing pad 100.

By adjusting the depth and / or width of the grooves 121, the amount of polishing fluid returned to the polishing surface can be adjusted.

Meanwhile, the polishing surface of the polishing pad 100 according to an embodiment of the present invention may not have an artificial groove. This is because, when a plurality of grooves are formed on the polishing surface, the uniformity of the polishing can be impaired due to a change in frictional force.

The polishing pad 100 of the present invention has a plurality of first through holes h1 formed sequentially along its circumference. The first through holes (h1) pass through the polishing layer (110) and the auxiliary layer (120). The polishing fluid supplied to the polishing surface of the polishing pad 100 flows along the polishing surface and at least a part thereof can flow to the back surface of the polishing pad 100 through the first through holes h1.

The first through holes h1 are formed on the outer side of the polishing pad 100 so that the polishing fluid can sufficiently stay on the polishing surface. For this, the distance between each of the plurality of first through holes and the outer peripheral portion of the polishing pad may be limited to 2 to 20 mm.

The polishing fluid flowing into the back surface of the polishing pad 100 through the first through holes h1 is discharged to the center of the polishing pad 100 along the grooves 121 formed in the back surface as the polishing pad 100 rotates Flow.

Since the grooves 121 according to the present invention have a convex spiral shape in the direction opposite to the rotating direction of the polishing pad 100, the polishing fluid introduced into the back side through the first through holes h1 is formed in the grooves 121 To the center side of the polishing pad. Hereinafter, the polishing fluid flow f2 at the back surface of the polishing pad 100 will be described in more detail with reference to Fig.

5 is a plan view for explaining the flow direction of the polishing fluid on the back surface of the polishing pad 100 according to the present invention, as viewed from the polishing surface side.

FIG. 5 illustrates one of the grooves 121 formed on the back surface of the polishing pad 100. FIG. Reference numeral 10 denotes a polishing fluid existing in the groove 121. A straight line connecting the center of the polishing pad 100 and the polishing fluid 100 is defined as L1 and a tangent of the groove 121 at the position of the polishing fluid 10 is referred to as L2, Is defined as &thetas;

The polishing fluid 10 present in the groove 121 is subjected to the inertial force F0 in a direction perpendicular to the straight line L1 as the polishing pad 100 rotates. This inertia force F0 is divided into F1 in the direction parallel to the tangent L2 and F2 in the direction perpendicular to the tangent L2. Unlike F 1, F 2 has a direction perpendicular to the tangent line L 2, and thus has no influence on the flow of the polishing fluid 10 in the grooves 121. Therefore, the polishing fluid 10 is moved to the center of the polishing pad 100 along the groove 121 by F1. Finally, the magnitude of the force for moving the polishing fluid 10 to the central portion of the polishing pad 100 by the inertia force F0 is F1 (= F0 占 sin?).

If the groove 121 has a convex spiral shape in the rotation direction of the polishing pad 100, the polishing fluid 10 will not be able to move to the center of the polishing pad 100 by the above-described principle.

On the other hand, centrifugal force in the direction parallel to the straight line L1 also acts on the polishing fluid 10. This centrifugal force is also divided by the force in the direction parallel to the tangent line L2 and the force in the direction perpendicular to the tangent L2. As described above, the force in the direction perpendicular to the tangent line L2 has no influence on the flow of the polishing fluid 10 in the grooves 121, and consequently the polishing fluid 10 is transferred to the polishing pad 100 by the centrifugal force The magnitude of the force to move to the outer side is the centrifugal force cos?.

As a result, it can be said that the inertial force (F0). Sin .theta. Must be larger than the centrifugal force cos .theta. In order for the polishing fluid 10 to move to the center side of the polishing pad 100 in the groove 121. [

2, the polishing pad 100 according to an embodiment of the present invention includes a plurality of second through holes h2 passing through the polishing layer 110 and the auxiliary layer 120, . The second through holes h2 are positioned closer to the center of the polishing pad 100 than the first through holes h1. Optionally, the plurality of second through holes (h2) are formed in the plurality of grooves (121).

The polishing fluid flowing along the grooves 121 formed on the back surface of the polishing pad 100 to the center of the polishing pad 100 flows from the back surface to the polishing surface through the plurality of second through holes h2, The result can be reused for polishing operations.

In summary, according to the present invention, at least a part of the polishing fluid used for the polishing operation while flowing on the polishing surface is divided into the first through holes (h1), the grooves (121) formed in the back surface and the second through holes h2) are sequentially supplied to the polishing surface.

FIG. 6 is a cross-sectional view illustrating a process for manufacturing a polishing pad according to an embodiment of the present invention. Referring to FIG.

First, an auxiliary layer 120a having a first surface and a second surface located on the opposite side of the first surface is prepared. The auxiliary layer 120a may be polyurethane or other synthetic resin.

A plurality of grooves 121 for the flow of abrasive fluid are formed on the second side of the auxiliary layer 120a. Each of the plurality of grooves 121 is formed to extend from the central portion to the outer side of the auxiliary layer 120a and has a convex spiral shape in a direction opposite to the rotating direction of the polishing pad.

An abrasive layer 110a is then provided on the first side of the auxiliary layer 120b. The polishing layer 110a according to the present invention is not particularly limited to any one structure. Examples of the abrasive layer 110a according to the present invention include a nonwoven fabric abrasive layer impregnated with a synthetic resin such as polyurethane, a porous polyurethane abrasive layer, and a non-porous polyurethane abrasive layer.

Then, first and second through holes (h1, h2) passing through both the polishing layer (110a) and the auxiliary layer (120b) are formed. The first through holes h1 are sequentially formed along the circumference within a range of 2 to 20 mm from the outer periphery of the polishing layer 110b and the auxiliary layer 120c. The second through hole (h2) may be formed in the grooves (121).

FIG. 7 is a cross-sectional view illustrating a polishing pad according to another embodiment of the present invention. Referring to FIG.

First, an initial pad 100a having a polishing surface and a rear surface located opposite to the polishing surface is prepared. Then, a plurality of grooves 121 for the flow of polishing fluid are formed on the back surface. Each of the plurality of grooves 121 is formed to extend from the central portion to the outer side of the initial pad 100a and has a convex spiral shape in a direction opposite to the rotation direction of the polishing pad.

Then, first and second through holes (h1, h2) passing through the initial pad (100b) in which the grooves (121) are formed are formed. The first through holes h1 are sequentially formed along the circumference within a range of 2 to 20 mm from the outer periphery of the polishing pad 100c. The second through hole (h2) may be formed in the grooves (121).

According to the present invention, since the circulating path for returning the polishing fluid used for polishing to the polishing surface of the polishing pad is provided, the polishing efficiency of the polishing work can be maximized. In addition, since the polishing fluid circulating path of the present invention can be applied to various types of polishing pads, various control of the polishing function becomes possible. Further, since at least a part of the polishing fluid is recycled, the polishing fluid can be used more efficiently, and as a result, the amount of polishing fluid used can be reduced.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited specifically to the scope of the following examples.

Example 1

On the back surface of a 1.5 mm thick non-woven polishing layer which is typically used for semiconductor polishing, an auxiliary layer having a thickness of 1.5 mm, in which spiral grooves having a depth of 1 mm and a width of 2 mm are formed in a circumferential direction, . Then, through holes having a diameter of 2 mm penetrating through the abrasive layer and the auxiliary layer along the grooves were formed at intervals of 5 mm, and then cut into a circle having a diameter of 500 mm to prepare a test pad.

Example 2

On the back surface of a 1.5 mm thick non-woven polishing layer which is typically used for semiconductor polishing, an auxiliary layer having a thickness of 1.5 mm, in which spiral grooves having a depth of 1 mm and a width of 2 mm are formed in a circumferential direction, . Then, through holes having a diameter of 2 mm penetrating through the abrasive layer and the auxiliary layer along the grooves were formed at intervals of 10 mm, and then cut into a circle having a diameter of 500 mm to prepare a test pad.

Example 3

On the back surface of a 1.5 mm thick non-woven polishing layer which is typically used for semiconductor polishing, an auxiliary layer having a thickness of 1.5 mm, in which spiral grooves having a depth of 1 mm and a width of 2 mm are formed in a circumferential direction, . Then, through holes having a diameter of 2 mm penetrating through the abrasive layer and the auxiliary layer along the grooves were formed at intervals of 20 mm, and then cut into a circle having a diameter of 500 mm to prepare a test pad.

Comparative Example 1

A test pad was prepared in the same manner as in Example 1, except that grooves were not formed on the back surface of the auxiliary layer.

Abrasion test

Using the test pads of Examples 1 to 3 and Comparative Example 1, silicon wafers of 200 mm in diameter were polished under the following conditions, respectively.

Abrasive condition

Polishing machine: Poli-500 Polisher from GNP Technology

- Polishing time: 10 minutes

- Down force: 250 g / cm < 2 > (3.5 psi)

- Polishing Plate Speed: 120 rpm

- Wafer carrier speed: 120 rpm

- polishing fluid flow rate: 700 ml / min

- abrasive fluid type: Nalco 2371, silica-based abrasive fluid diluted with DIW and polishing fluid 15: 1

- Polishing test after 10 minutes of dressing using diamond dresser

- Discard the initial 3 test values and repeat the subsequent polishing test three times to obtain the average removal rate and obtain the 1st removal rate (nm / min).

- Perform polishing test for 2 hours using dummy wafer

- Discard the initial 3 test values and repeat the subsequent polishing test 3 times to obtain the average removal rate and obtain the 2nd removal rate (nm / min).

- Perform polishing test for 2 hours using dummy wafer again.

- Discard the initial 3 test values and repeat the subsequent polishing test 3 times to obtain the average removal rate and obtain the 3rd removal rate (nm / min).

The results of the measurement of the polishing rate of the silicon wafer subjected to the polishing (polishing) as described above are shown in Table 1.

Result of polishing rate measurement of polished wafers division Example 1 Example 2 Example 3 Comparative Example 1 The first polishing rate (1stRR) 560 nm 541 nm 533 nm 507 nm Second polishing rate (2ndRR) 554 nm 538 nm 525 nm 497 nm 3 ratios (3rdRR) 547 nm 530 nm 523 nm 484 nm

As can be seen from the above Table 1, even though the same amount of polishing fluid was used, the polishing pads of Examples 1 to 3 in which grooves were formed on the back surface were superior to the polishing pads of Comparative Example 1 in which grooves were not formed And the polishing rate is shown.

100: polishing pad 110: polishing layer 120: auxiliary layer

Claims (14)

delete delete delete A polishing pad comprising a polishing surface and a back surface located opposite to the polishing surface,
A plurality of grooves for the flow of the polishing fluid are formed on the back surface,
Wherein the polishing pad has a plurality of first through holes for allowing a polishing fluid provided on the polishing surface to flow to the back surface, the plurality of first through holes being spaced by the same distance from an outer circumferential portion of the polishing pad, And is formed along the circumference of the pad,
Wherein the same distance between each of the plurality of first through holes and an outer peripheral portion of the polishing pad is 2 to 20 mm. 5. The method of claim 4,
Wherein the polishing pad has a plurality of second through holes for allowing the polishing fluid that has flowed to the back surface through the first through holes to flow from the back surface to the polishing surface. 6. The method of claim 5,
And the plurality of second through holes are formed in the plurality of grooves. The method according to claim 6,
The polishing pad comprising: an auxiliary layer having the back side; And an abrasive layer located on the auxiliary layer and having the abrasive surface,
Wherein the plurality of grooves are formed only in the auxiliary layer,
Wherein the first and second through holes penetrate both the polishing layer and the auxiliary layer. delete Preparing an initial pad having a polishing surface and a back surface located opposite to the polishing surface;
Forming a plurality of grooves for flow of the polishing fluid on the back surface; And
Forming first through holes through the initial pad,
The first through holes are formed along the circumference of the initial pad by the same distance from the circumference of the initial pad,
Wherein the same distance between each of the first through holes and the outer periphery of the initial pad is 2 to 20 mm. 10. The method of claim 9,
Wherein each of the plurality of grooves is formed to extend from a central portion of the initial pad to an outer side and is formed in a convex spiral shape in a direction opposite to a rotating direction of the polishing pad. 11. The method of claim 10,
Further comprising forming second through holes through the initial pad,
And the second through holes are formed in the grooves. In the method of manufacturing a polishing pad,
Providing an auxiliary layer having a first side and a second side opposite to the first side;
Forming a plurality of grooves for the flow of abrasive fluid on the second surface;
Providing an abrasive layer on a first side of the auxiliary layer; And
Forming first through holes through both the polishing layer and the auxiliary layer,
Wherein the plurality of first through holes are formed along the circumference of the polishing pad by an equal distance from an outer circumferential portion of the polishing pad,
Wherein the same distance between each of the first through holes and an outer peripheral portion of the polishing pad is 2 to 20 mm. 13. The method of claim 12,
Wherein each of the plurality of grooves extends from a central portion of the auxiliary layer to an outer side thereof and is formed in a convex spiral shape in a direction opposite to a rotation direction of the polishing pad. 14. The method of claim 13,
Further comprising forming second through holes through both the polishing layer and the auxiliary layer,
And the second through holes are formed in the grooves.

Images