TWI510328B - Base layer, polishing pad including the same and polishing method - Google Patents

Description

Base layer, polishing pad including the same, and grinding method

The present invention relates to a substrate layer, a polishing pad including the substrate layer, and a polishing method, and more particularly to a substrate layer having good shear resistance characteristics with an adhesive layer, and a polishing pad including the substrate layer. And grinding methods.

As the industry advances, flattening processes are often adopted as processes for producing various components. In the flattening process, the chemical mechanical polishing process is often used by the industry. Generally, the chemical mechanical polishing process is performed by supplying a polishing liquid having a chemical mixture onto a polishing pad, applying a pressure to the object to be pressed onto the polishing pad, and moving the object and the polishing pad relative to each other. . By the mechanical friction generated by the relative motion and the chemical action of the polishing liquid, the surface layer of some objects is removed, and the surface thereof is gradually flattened to achieve the purpose of planarization.

Conventionally, a polishing pad for a semiconductor wafer has been known which uses a polishing pad having a multi-layer structure, and its structure substantially includes an abrasive layer, an adhesive layer, and a base layer. Wherein, the polishing layer has an abrasive surface which can be in direct contact with the object to be polished, and micropores, grooves and/or through-hole patterns can be formed thereon; the base layer is adhered to the underside of the polishing layer and fixed on the grinding machine, which is porous Sexual structure, with a large number of holes of different sizes, the ratio of the hole area to the total area is called the pore ratio, the hole is generally more than 20%, or even up to 60%; and the adhesive layer The main purpose is to provide adhesion to closely bond the abrasive layer to the substrate layer.

When performing the polishing process, the other side of the substrate layer not in contact with the adhesive layer is first adhered to the base of the polishing machine by another adhesive layer, and then the polishing pad is used to polish the object (such as a wafer). Or substrate) for the grinding process.

However, since the base layer is a porous structure, there are many holes of different sizes everywhere, and there are also a plurality of holes on the contact surface that is adhered to the adhesive layer, and these holes are subject to shear force during the grinding process. The action causes deformation to squeeze the air, and the squeezed air pushes the adhesive layer originally attached to the hole, so that the contact surface between the base layer and the adhesive layer produces minute protrusions, and the shearing force increases with the grinding time. Under continuous action, the contact surface between the base layer and the adhesive layer becomes more uneven, which results in a decrease in the quality of the polishing and even affects the process misalignment.

In view of this, the present invention provides a substrate layer having good shear resistance characteristics with the adhesive layer.

The invention provides a polishing pad, comprising an abrasive layer and a base layer, the base layer is disposed under the polishing layer, and comprises a porous inner layer and at least one surface layer, wherein the porous inner layer has an upper surface and a lower surface, and the surface layer can have a pole A small number of holes (having a hole ratio of not more than 0.3%) or no holes at all, the surface layer being disposed on at least one of the upper surface and the lower surface of the porous inner layer.

At the same time, the present invention also proposes a base layer suitable for the abrasive layer of the pad polishing pad, the base layer comprises a porous inner layer and a surface layer, the porous inner layer has an upper surface and a lower surface, and the surface layer can have a very small number of holes ( The pore ratio is not more than 0.3% or no pores at all, and the surface layer is disposed on at least one of the upper surface and the lower surface of the porous inner layer.

At the same time, the present invention also proposes a grinding method suitable for grinding a substrate, the grinding method comprising the following steps. First, a polishing pad is provided. Next, pressure is applied to the substrate to press onto the polishing pad. The substrate and the polishing pad are then provided with relative motion. Wherein, the polishing pad comprises an abrasive layer and a base layer. The base layer is disposed below the abrasive layer, and the base layer includes a porous inner layer and at least one skin layer. The porous inner layer has an upper surface and a lower surface. The surface layer may have a very small number of holes (having a hole ratio of not more than 0.3%) or no holes at all, and the surface layer is disposed on at least one of the upper surface and the lower surface of the porous inner layer.

Based on the above, since the surface layer in the base layer proposed by the present invention has a void ratio of not more than 0.3% or even no pores, in the case where the surface layer does not contain any pores, the contact surface of the surface layer and the adhesive layer is not bonded. With any holes, it is of course not known that the base layer has a porous structure and the contact surface between the adhesive layers is uneven. When the surface layer contains a very small number of holes (the hole ratio is not more than 0.3%), the number of holes collected on the contact surface to which the adhesive layer is attached is extremely small, although these holes are also deformed by the shearing force. Air, but because the number of holes is extremely small, it is too small to collect enough squeeze air to push the adhesive layer originally attached to the hole, which does not cause unevenness of the contact surface and does not affect the polishing quality. Therefore, the base layer disclosed in the present invention can be tightly bonded to the adhesive layer by the surface layer, so that the base layer and the adhesive layer have better shear resistance characteristics. Further, in the polishing pad proposed by the present invention, since the underlayer in the polishing pad has a surface layer having a hole ratio of not more than 0.3% or not containing a hole, the chance of occurrence of debonding of the adhesive layer can be reduced.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a cross-sectional view showing a polishing pad according to a first embodiment of the present invention. 2 is a cross-sectional view showing a polishing pad according to a second embodiment of the present invention. 3 is a cross-sectional view showing a polishing pad according to a third embodiment of the present invention. 4 is a scanning electron micrograph (SEM) of a substrate layer according to an embodiment of the present invention.

Referring to FIG. 1 to FIG. 3 simultaneously, the polishing pad 100 disclosed in the present invention includes an abrasive layer 102 and a base layer 104. Wherein, the polishing layer 102 is made of a polymer material, and the polymer material may be, for example, a polyurethane, and the polishing layer 102 has an abrasive surface which can be bonded to an object to be polished (such as a wafer or a substrate). Direct contact, on which micropores, grooves and/or through-hole patterns may be formed.

The base layer 104 is suitable for use in the abrasive layer 102 in the pad polishing pad 100. The base layer 104 is bonded under the polishing layer 102, and the base layer 104 includes a porous inner layer 106 and at least one skin layer 108. Wherein, the surface layer 108 is a non-porous structure having a very small number of pores or even no pores, and thus the surface layer 108 may also be referred to as a non-porous surface layer 108.

The material of the porous inner layer 106 is, for example, made of the same material as the non-porous surface layer 108, and the porous inner layer 106 and the material of the non-porous surface layer 108 have the same chemical structure, and the material thereof can be, for example, low. Density polyethylene, or a mixture of low density polyethylene and ethylene vinyl acetate. In the process, the porous inner layer 106 and the non-porous surface layer 108 can be formed by the same foaming process, and by controlling the foaming time and the foaming temperature, the same material can be simultaneously formed with the porous inner layer 106 and non- Porous skin layer 108. In other words, the porous inner layer 106 and the non-porous surface layer 108 are integrally formed, and are not separately formed and rejoined (or bonded) together, and the porous inner layer 106 and the non-porous surface layer 108 are There is no obvious hierarchical relationship. In detail, although the names of the porous inner layer 106 and the non-porous surface layer 108 are both "layers" in the present specification, in fact, the two layers can be seen from the scanning electron microscope (SEM) of FIG. (106, 108) There is no obvious seam, which is a two-layer structure formed by itself.

The porous inner layer 106 has an upper surface 110 and a lower surface 112, and the porous inner layer 106 has a plurality of minute holes 114 of different sizes, and the pores 114 have a pore size distribution of, for example, 10 μm to 400 μm. In an embodiment, The pores 114 may have an average pore diameter of from 100 μm to 250 μm.

Wherein, the non-porous skin layer 108 may selectively contain only a few pores or no pores at all, and in one embodiment, the pore ratio in the non-porous skin layer 108 is not more than 0.3% (for example: Not more than 0.2%; not more than 0.1%; or even 0%), the pore ratio mentioned in the description is to be explained here as the pore area in the non-porous surface layer 108. The ratio of the areas, the hole ratio is not more than 0.3%, that is, less than or equal to 0.3%. In this embodiment, although the non-porous surface layer 108 still has a plurality of minute holes, the number of holes is much reduced compared to the conventional porous structure of the base layer (its pore ratio is more than 20%), so although there are still The number of holes is too small, so that the contact surface between the non-porous surface layer 108 and the adhesive layer cannot be gathered in a sufficient amount to cause the squeeze air to push to produce minute protrusions, which makes the contact surface uneven and causes the polishing quality. A falling phenomenon occurs.

Of course, the manufacturer can determine the void ratio in the non-porous skin layer 108 by controlling the foaming time and the foaming temperature. In one embodiment, the pore ratio in the non-porous skin layer 108 is 0%. That is, the non-porous surface layer 108 does not contain holes at all. Since the pores are not contained at all, of course, no pores are accumulated on the contact surface between the non-porous surface layer 108 and the adhesive layer, and there is no possibility that the contact surface is not flat and the polishing quality is lowered.

Meanwhile, the non-porous surface layer 108 may be selectively disposed on at least one of the upper surface 110 and the lower surface 112 of the porous inner layer 106. In detail, the non-porous surface layer 108 may be disposed only in the porous inner layer 106. The upper surface 110, or only the lower surface 112 of the porous inner layer 106, can be disposed at the same time on the upper and lower surfaces (110, 112) of the porous inner layer 106, and the manufacturer can look at the product requirements. The production mode is adjusted to produce a non-porous skin layer 108 that is disposed at different locations or that has a different ratio of voids.

As shown in FIG. 1, the non-porous surface layer 108 is disposed on the upper surface 110 of the porous inner layer 106, and the non-porous surface layer 108 is disposed between the porous inner layer 106 and the polishing layer 102.

As shown in FIG. 2, the non-porous surface layer 108 is disposed on the lower surface 112 of the porous inner layer 106. Accordingly, the non-porous surface layer 108 is interposed between the porous inner layer 106 and the susceptor 10 of the polishing machine. .

As shown in FIG. 3, the non-porous surface layer 108 is simultaneously disposed on the upper surface 110 and the lower surface 112 of the porous inner layer 106. Accordingly, the non-porous surface layer 108 on the upper surface 110 is interposed between the porous inner layer. Between 106 and polishing layer 102, non-porous skin layer 108 on lower surface 112 is interposed between porous inner layer 106 and susceptor 10 of the polishing machine table.

The thickness of the non-porous surface layer 108 is, for example, greater than 5 μm. In one embodiment, the non-porous surface layer 108 may have a thickness of 8 μm to 35 μm. The thickness selection of the non-porous skin layer 108 can be controlled by adjusting the parameters at the time of manufacture of the base layer 104, for example, to adjust the surface temperature of the mold used for batch production, or to adjust the surface temperature of the roller used in continuous production. The surface temperature of the mold or the roller is, for example, lower than 30 ° C, 20 ° C, 10 ° C, or even lower than 5 ° C. Generally, the lower the surface temperature of the mold or the roller, the thickness of the non-porous surface layer 108 is produced. The thicker it is. In addition, the base layer having a porous surface layer may be manufactured first, and then the porous surface layer is heated and pressurized to change the surface layer into a non-porous surface layer, wherein the non-porous surface layer can be controlled by adjusting temperature and pressure parameters. The thickness. The surface roughness of the non-porous skin layer 108 is, for example, less than 15 μm. For example, the surface roughness of the non-porous surface layer 108 is, for example, 3 μm to 10 μm. In the process, a non-porous surface layer 108 may be subjected to a surface treatment procedure to increase the surface adhesion of the non-porous surface layer 108 before the non-porous skin layer 108 is adhered to the adhesive layer, wherein the surface treatment procedure For example, it may be a plasma treatment.

In addition, the polishing pad 100 further includes an adhesive layer 116 disposed between the polishing layer 102 and the base layer 104 for bonding the polishing layer 102 and the base layer 104 to form the polishing pad 100. The material of the adhesive layer 116 is, for example, Pressure Sensitive Adhesive (PSA).

As shown in FIG. 1, when the non-porous surface layer 108 is disposed on the upper surface 110 of the porous inner layer 106, since the non-porous surface layer 108 has a very small number of holes (the hole ratio is not more than 0.3%), or does not contain any In the case where the surface layer does not contain any pores, the contact surface of the surface layer and the adhesive layer does not have any pores. Of course, there is no known that the contact surface between the adhesive layer and the adhesive layer is uneven due to the porous structure of the base layer. The phenomenon occurs. When the surface layer contains a very small number of holes (the hole ratio is not more than 0.3%), the non-porous surface layer 108 (the base layer 104) has only a very small number of holes on the contact surface to which the adhesive layer 116 is attached, in the grinding procedure. In the process, when the non-porous surface layer 108 (the base layer 104) is subjected to the shearing force, the opportunity to cause the micro-bumps on the contact surface between the base layer 104 and the adhesive layer 116 to be caused by the deformation of the air by the squeezed air can be reduced, and the adhesion can still occur. The layer 116 is in close contact, so that the polishing layer 102 and the base layer 104 can maintain a good adhesion state during the polishing process.

As shown in FIG. 2, when the lower surface 112 of the porous inner layer 106 is provided with the non-porous surface layer 108, the side of the non-porous surface layer 108 not in contact with the porous inner layer 106 and the side of the other adhesive layer 118. The other side of the adhesive layer 118 is bonded to the base 10 of the polishing machine. Similarly, since the non-porous surface layer 108 has a very small number of holes (the hole ratio is not more than 0.3%), or even does not contain any holes, the non-porous surface layer 108 (the base layer 104) is in contact with the adhesive layer 118. Only a very small number of holes or no holes at all, during the grinding process, the non-porous surface layer 108 (base layer 104) can be reduced by the shear force to cause the hole deformation to squeeze the air to cause the base layer 104 and the adhesive layer 118 The intervening contact surface creates a slight protrusion and can still be closely adhered to the adhesive layer 118, so that the polishing pad 100 can maintain a good adhesion state with the polishing machine during the polishing process.

As shown in FIG. 3, when the upper surface 110 and the lower surface 112 of the porous inner layer 106 are simultaneously provided with the non-porous surface layer 108, the non-porous surface layer 108 (the base layer 104) is bonded to the adhesive layer (116, 118). The contact surface has only a very small number of holes or no holes at all. During the grinding process, the non-porous surface layer 108 (the base layer 104) can reduce the deformation of the hole and cause the base layer 104 to be squeezed by the shearing force. The contact surface with the adhesive layers 116, 118 creates an opportunity for the micro bumps to occur, and can still be closely adhered to the adhesive layers 116, 118, so that the polishing layer 102 and the base layer 104 can be maintained well during the polishing process. Adhesive state, and the polishing pad 100 can maintain a good adhesion state with the grinding machine during the grinding process.

In the present invention, in order to confirm the effect of the polishing pad proposed by the present invention, a shear resistance test was actually carried out.

Experimental example

Hereinafter, the characteristics of the underlayer in the polishing pad of the present embodiment will be described by performing actual experimental tests. In the experimental test, the test methods and sample settings used are as follows.

Shear resistance test method: The shear resistance maintenance time of the basal layer was measured by the ASTM D3654 standard test method.

Adhesive layer material: acrylic-based adhesive.

Sample: The polishing pad is obtained by laminating the polishing layer and the base layer by an adhesive layer.

Experimental Example 1 differs from Comparative Example 1 in having different base layers.

Experimental Example 1: A base layer having a porous inner layer and a non-porous surface layer.

Comparative Example 1: a base layer having the same material and pore structure as that of Experimental Example 1, but having no non-porous surface layer, that is, a surface layer having a porous base layer, for example, a non-base layer in Experimental Example 1 The resulting skin layer is removed from the porous skin layer.

Hereinafter, experimental results for describing the adhesion characteristics between the base layer and the adhesive layer are summarized in Table 1 below.

As can be seen from Table 1, in Experimental Results, it can be seen from Experimental Example 1 and Comparative Example 1 that the shear strength maintenance time of Experimental Example 1 having a non-porous surface layer in the base layer was 74 hours, compared with the porosity. The shear resistance of the surface layer Comparative Example 1 was maintained for 14 hours, and the improvement was over 400%. In the grinding process, the polishing pad must remain unable to fall off under the shearing force for a long time, so the shear retention time is an important indicator for testing the performance of the polishing pad. Accordingly, it is necessary to have a base layer having a non-porous surface layer.

In the shear strength maintenance time test, after the non-porous surface layer 108 in the base layer 104 is bonded to the adhesive layer (116 or 118), the base layer 104 and the adhesive layer are applied when a shear force is applied to the non-porous surface layer 108 ( There is a first hold time between 116 or 118). In the case of a base layer having the same material and pore structure but having no non-porous surface layer, that is, when the porous skin layer is applied to the same adhesive layer and applied with the same shear force, for example, the non-porous surface layer 108 is removed. When the rear porous inner layer 106 is applied to the same adhesive layer and the same shear force is applied, the base layer 104 and the adhesive layer have a second holding time, and the first maintenance time is at least 20% more than the second maintenance time (for example: More than 50%, 100%, 200%, 300%, 400%, or 500%).

Based on the above, since the non-porous surface layer 108 in the base layer 104 has only a very small number of holes or no holes at all, the base layer 104 can be tightly bonded to the adhesive layer (116 or 118) by the non-porous surface layer 108. The base layer 104 and the adhesive layer have better shear resistance characteristics.

FIG. 5 is a flow chart showing a polishing method according to an embodiment of the present invention. This grinding method is suitable for grinding a substrate.

Referring to FIG. 5, first, step S100 is performed to provide a polishing pad. The polishing pad is, for example, the polishing pad 100 in the embodiment of Figures 1-3. The polishing pad comprises an abrasive layer and a base layer, the base layer is attached to the underside of the polishing layer, and comprises a porous inner layer and a surface layer (non-porous surface layer), wherein the porous inner layer has an upper surface and a lower surface, and the surface layer (non-porous) The surface layer can have a very small number of holes (the hole ratio is not more than 0.3%) or no holes at all (the hole ratio is 0%), and the surface layer (non-porous surface layer) can selectively adhere only to the porous layer. The upper surface of the inner layer or the lower surface layer which is only bonded to the porous inner layer or the upper and lower surfaces of the porous inner layer at the same time.

Next, in step S102, pressure is applied to the substrate to be pressed against the polishing pad to bring the substrate into contact with the polishing pad.

Then, step S104 is performed to provide relative motion to the substrate and the polishing pad to grind the substrate with the polishing pad to achieve planarization.

In summary, in an embodiment, the base layer disclosed in the present invention has better shear resistance characteristics with the adhesive layer. In one embodiment, the polishing pad disclosed in the present invention can reduce the chance of occurrence of minute protrusions on the contact surface between the substrate layer and the adhesive layer.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10. . . Pedestal

100. . . Abrasive pad

102. . . Abrasive layer

104. . . Base layer

106. . . Porous inner layer

108. . . surface layer

110. . . Upper surface

112. . . lower surface

114. . . Hole

116, 118. . . Adhesive layer

S100, S102, S104. . . Step label

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

2 is a cross-sectional view showing a polishing pad according to a second embodiment of the present invention.

3 is a cross-sectional view showing a polishing pad according to a third embodiment of the present invention.

4 is a scanning electron micrograph (SEM) of a substrate layer according to an embodiment of the present invention.

FIG. 5 is a flow chart showing a polishing method according to an embodiment of the present invention.

10. . . Pedestal

100. . . Abrasive pad

102. . . Abrasive layer

104. . . Base layer

106. . . Porous inner layer

108. . . Surface layer, non-porous surface layer

110. . . Upper surface

112. . . lower surface

114. . . Hole

116, 118. . . Adhesive layer

Claims (32)

A polishing pad comprising: an abrasive layer; and a substrate layer disposed under the polishing layer, the substrate layer comprising: a porous inner layer having an upper surface and a lower surface; and a second surface layer having a void ratio More than 0.3%, and disposed on the upper surface and the lower surface of the porous inner layer. The polishing pad according to claim 1, wherein each of the surface layers is a non-porous surface layer and has a void ratio of 0%. The polishing pad according to claim 2, wherein the porous inner layer and the non-porous surface layer are made of the same material and integrally formed. The polishing pad of claim 2, wherein the non-porous surface layer has a thickness of more than 5 μm. The polishing pad according to claim 2, wherein the non-porous surface layer has a thickness of 8 μm to 35 μm. The polishing pad according to any one of claims 2 to 5, wherein the non-porous surface layer has a surface roughness of less than 15 μm. The polishing pad according to claim 6, wherein the non-porous surface layer has a surface roughness of from 3 μm to 10 μm. The polishing pad according to any one of claims 2 to 5, wherein the pores in the porous inner layer have a pore size distribution of from 10 μm to 400 μm. The polishing pad according to claim 8, wherein the pores in the porous inner layer have an average pore diameter of from 100 μm to 250 μm. The polishing pad of claim 1, wherein the substrate layer is made of low density polyethylene, or a mixture of low density polyethylene and ethylene vinyl acetate. The polishing pad according to any one of claims 1 to 5, further comprising a second adhesive layer disposed between the polishing layer and the substrate layer and between the substrate layer and a polishing machine. The polishing pad according to claim 11, wherein the substrate layer is adhered to each of the adhesive layers and tested by a shear stress maintenance time. When a shear force is applied to each of the surface layers, the substrate layer and each layer are respectively The adhesive layer has a first holding time. When the shearing force is applied to the porous inner layer, the base layer and each of the adhesive layers have a second holding time. The first maintaining time is longer than the second holding time. At least 20%, wherein the shear stress maintenance time test is the ASTM D3654 standard test method. The polishing pad of any one of claims 2 to 5, wherein the non-porous skin layer comprises a plasma treated non-porous skin layer. A base layer suitable for use in a polishing layer of a pad-polished pad, comprising: a porous inner layer having an upper surface and a lower surface; and a second surface layer having a void ratio of not more than 0.3% and disposed in the porous layer The upper surface and the lower surface of the inner layer. The base layer according to claim 14, wherein each of the surface layers is a non-porous surface layer and has a void ratio of 0%. The base layer according to claim 15, wherein the porous inner layer and the non-porous surface layer are made of the same material and integrally formed. The substrate layer of claim 15, wherein the non-porous skin layer has a thickness of more than 5 μm. The underlayer according to claim 17, wherein the non-porous surface layer has a thickness of from 8 μm to 35 μm. The substrate layer according to any one of claims 15 to 18, wherein the non-porous skin layer has a surface roughness of less than 15 μm. The base layer according to claim 19, wherein the non-porous surface layer has a surface roughness of from 3 μm to 10 μm. The substrate layer according to any one of claims 15 to 18, wherein the pores in the porous inner layer have a pore size distribution of from 10 μm to 400 μm. The underlayer according to claim 21, wherein the pores in the porous inner layer have an average pore diameter of from 100 μm to 250 μm. The base layer of claim 14, wherein the base layer is made of low density polyethylene or a mixture of low density polyethylene and ethylene vinyl acetate. The substrate layer of any one of claims 15 to 18, wherein the non-porous skin layer comprises a plasma treated non-porous skin layer. A grinding method, suitable for grinding a substrate, comprising: providing a polishing pad; Applying a pressure to the substrate to press against the polishing pad; and providing a relative movement to the substrate and the polishing pad, wherein the polishing pad comprises: an abrasive layer; and a substrate layer disposed under the polishing layer, The base layer includes: a porous inner layer having an upper surface and a lower surface; and a second surface layer having a void ratio of not more than 0.3% and disposed on the upper surface and the lower surface of the porous inner layer. The polishing method according to claim 25, wherein each of the surface layers is a non-porous surface layer and has a void ratio of 0%. The polishing method according to claim 26, wherein the porous inner layer and the non-porous surface layer are made of the same material and integrally formed. The grinding method of claim 26, wherein the non-porous skin layer has a thickness of more than 5 μm. The polishing method according to any one of claims 26 to 28, wherein the non-porous surface layer has a surface roughness of less than 15 μm. The polishing method according to any one of claims 26 to 28, wherein the pores in the porous inner layer have a pore size distribution of from 10 μm to 400 μm. The method of claim 25, wherein the substrate layer is made of low density polyethylene or a mixture of low density polyethylene and ethylene vinyl acetate. The method of polishing according to any one of claims 26 to 28, wherein the non-porous skin layer comprises a plasma treated non-porous skin layer.