CN111183003A

CN111183003A - Surface-treated polishing pad window and polishing pad comprising same

Info

Publication number: CN111183003A
Application number: CN201880064696.0A
Authority: CN
Inventors: 尹晟勋; 徐章源; 安宰仁; 尹锺旭; 许惠映
Original assignee: SKC Co Ltd
Current assignee: Sk Enpus Co ltd
Priority date: 2017-08-07
Filing date: 2018-08-06
Publication date: 2020-05-19
Anticipated expiration: 2038-08-06
Also published as: TW201919818A; WO2019031788A1; CN111183003B; TWI721300B; KR101945874B1

Abstract

Embodiments relate to a surface-treated window for a polishing pad, which can prevent errors that may occur in detecting an endpoint due to abrasion of the window in a CMP process, and a polishing pad including the same.

Description

Surface-treated polishing pad window and polishing pad comprising same

Technical Field

Background

A polishing pad for a Chemical Mechanical Planarization (CMP) process is an essential element and plays an important role in a CMP process for manufacturing a semiconductor. It plays an important role in achieving the performance of the CMP process. The polishing pad for the CMP process is used to remove unnecessary portions on a wafer and smooth the surface of the wafer by a uniform polishing operation in the CMP process.

In recent years, various methods have been proposed to measure the thickness of a wafer and detect the end point of a CMP process. For example, in order to determine the flatness of the wafer surface in situ, a method has been proposed in which a window is installed in a polishing pad and the thickness of the wafer is measured by a reflected beam generated by a laser through the window. In the in-situ method, the window must keep the intensity of the incident light constant, and the deviation of the transmittance before and after grinding must be small to minimize the error in detecting the endpoint.

Alternatively, korean patent No. 10-1109156 discloses a polishing pad including an anti-scattering layer for reducing light scattering occurring at the lower side of a window.

Disclosure of Invention

Technical problem

Accordingly, it is an object of an embodiment to provide a surface-treated window for a polishing pad capable of preventing an error that may occur in detecting an endpoint due to abrasion of the window in a CMP process, and a polishing pad including the same.

Technical scheme for solving technical problem

To achieve the above object, one embodiment provides a surface-treated window for a polishing pad, which has a transmittance of 0.1% to 1.5% for light of 400nm and a transmittance of 4.5% to 7.5% for light of 670nm before polishing.

Another embodiment provides a polishing pad comprising the surface-treated window for a polishing pad.

Another embodiment provides a method of preparing a surface-treated window for a polishing pad, comprising: (1) preparing a window for a polishing pad by mixing a urethane-based prepolymer, a curing agent, and a reaction rate controlling agent; and

(2) one side of the window is subjected to a surface treatment,

wherein the window has a transmission of 0.1% -1.5% for 400nm light and a transmission of 4.5% -7.5% for 670nm light before lapping.

The invention has the advantages of

The window of the embodiment has a surface-treated side surface so that it has an effect of preventing an error that may occur in detecting an endpoint due to abrasion of the window in a CMP process.

Drawings

Fig. 1 is a cross-sectional view of an embodiment of a polishing pad.

Detailed Description

One embodiment provides a surface treated window for an abrasive pad having a transmittance of 0.1% to 1.5% for light at 400nm and a transmittance of 4.5% to 7.5% for light at 670nm before abrading.

The window may have a transmission of 5.5% to 9.5% for 800nm light before milling. In particular, the window may have a transmittance of 0.5% -1.0% for 400nm light, 4.5% -6.5% for 670nm light, and 6.5% -8.5% for 800nm light before lapping.

The window has a transmission variation within + -10% for 400nm light. The transmittance change can be calculated by the following formula 1.

[ formula 1]

In the above formula 1, the transmittance after the polishing is a transmittance measured after polishing the silicon oxide at a speed of 150rpm for 20 hours.

Specifically, the window may have a change in transmittance for 400nm light of 5% to 10%.

Additionally, the window may have a change in transmission to 670nm of light within 5%. In particular, the window may have a change in transmission for 670nm light of 0.1% to 5%.

Further, the window may have a variation in transmittance to 800nm of light within ± 10%. Specifically, the window may have a change in transmittance of-10% to-1% for 800nm of light.

The haze of the window having a width of 20mm, a length of 60mm, and a thickness of 2.3mm may be 85% -98%. Specifically, the haze of the window having a width of 20mm, a length of 60mm, and a thickness of 2.3mm may be 90% to 98%.

The window may have a surface roughness (Ra) of 1.0-5.0 μm, 2.0-4.0 μm, or 2.0-3.5 μm before grinding.

The window may be formed from a window composition comprising a urethane based prepolymer, a curing agent, and a reaction rate controlling agent. It may contain unreacted isocyanate groups (NCO).

The prepolymer generally means a polymer having a relatively low molecular weight, in which the degree of polymerization is adjusted to an intermediate level, in order to conveniently mold a molded article to be finally produced in the course of its preparation. The prepolymer may be formed alone or after reaction with other polymerizable compounds. Specifically, the urethane based prepolymer may be prepared by reacting an isocyanate compound with a polyol, and may include unreacted isocyanate groups (NCO).

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

The reaction rate controlling agent may be at least one selected from the group consisting of tertiary amine-based compounds (tertiary amine-based compounds) and organometallic-based compounds (organometallic-based compounds). In addition, the reaction rate controlling agent may be a reaction accelerator or a reaction retarder.

The window may be non-foam. Since the window is free of microbubbles, the possibility of the polishing liquid penetrating into the polishing pad can be reduced, thereby improving the accuracy of optical detection of the end point and preventing damage to the light-transmitting region.

Polishing pad

Another embodiment provides a polishing pad comprising a surface treated window as described above for a polishing pad.

The polishing pad may include: a polishing layer having a through-hole formed therein; and a surface-treated window inserted into the through-hole.

Referring to fig. 1, a polishing pad according to one embodiment includes a polishing layer (101) having a first through-hole (201) formed therein; a support layer (102), the support layer (102) having a second through-hole (203) formed in a region where a first through-hole (201) is formed; an adhesive layer (103), the adhesive layer (103) being interposed between the polishing layer and the support layer and having a third through-hole (203) formed in a region where the first through-hole is formed; and a window (104), the window (104) being inserted into the first through hole and adhered to the adhesive layer.

The polishing layer may be formed from a polishing layer composition comprising a urethane-based prepolymer, a curing agent, a reaction rate controlling agent, and a foaming agent. The urethane based prepolymer may be prepared by reacting an isocyanate compound with a polyol, and may include unreacted isocyanate groups (NCO).

The curing agent and reaction rate controlling agent are as described above in the section on the window.

The foaming agent is not particularly limited as long as it is generally used to form pores (voids) in the polishing pad. For example, the foaming agent may be at least one selected from a solid foaming agent having pores, a liquid foaming agent filled with a volatile liquid, and an inert gas.

The thickness of the polishing layer is not particularly limited. For example, it may be 0.8mm to 5.0mm, 1.0mm to 4.0mm or 1.0mm to 3.0 mm.

The window may have the same size as the through hole in the abrasive layer. In addition, the thickness of the window may be equal to or less than the thickness of the abrasive layer. In particular, the thickness of the window may be less than the thickness of the abrasive layer.

The window may have a wear rate that is the same as or slightly higher than the wear rate of the abrasive layer. In this case, it is possible to prevent a problem that only the window portion protrudes after polishing is performed for a certain period of time, thereby generating scratches on the wafer to be polished.

The window may preferably have a hardness similar to the polishing layer of the polishing pad. In this case, the problem that the wafer surface is damaged by the occurrence of the protrusion portion in the CMP process can be prevented.

Method of preparing surface-treated window for polishing pad

Another embodiment provides a method of preparing a surface-treated window for a polishing pad, comprising: (1) preparing a window for a polishing pad by mixing a urethane based prepolymer, a curing agent, and a reaction rate controlling agent; and

(2) one side of the window is subjected to a surface treatment,

Step (1)

In this step, a window for a polishing pad is prepared by mixing a urethane prepolymer, a curing agent, and a reaction rate controlling agent.

The urethane based prepolymer, curing agent and reaction rate controlling agent are as described above in the section on windows.

Step (2)

In this step, one side of the window is surface-treated.

The surface treatment may include a method of performing a sand blasting (blasting treatment), a wrinkling (or embossing) treatment, an etching (or corona discharge) treatment, a laser irradiation (laseriradation) treatment, or the like on one side of the window; a method of forming a pattern on one side of a window using a metal roller, a rubber roller, or an emboss roller having a predetermined surface shape; and a method of grinding with an abrasive material such as sandpaper. Specifically, the surface treatment may be performed with an abrasive. More specifically, the surface treatment may be a treatment of one side of the window with an abrasive at a rotation speed of 100rpm to 1,000rpm and a pressure of 0.1psi to 3.0psi for 10 to 60 seconds.

The surface treatment may be performed in such a manner that the surface roughness of the window is 1.0 to 5.0 μm. Specifically, the surface treatment may be performed in such a manner that the surface roughness of the window is 2.0 to 4.0 μm.

The surface treated window may have a transmittance of 5.5% to 9.5% for 800nm light before grinding.

Specifically, the surface-treated window may have a transmittance of 0.5% to 1.0% for 400nm light, a transmittance of 4.5% to 6.5% for 670nm light, and a transmittance of 6.5% to 8.5% for 800nm light before grinding.

The surface treated window may have a change in transmission to 400nm light within ± 10%. The transmittance change can be calculated by the following formula 1.

[ formula 1]

Specifically, the surface-treated window may have a transmittance change of 5% to 10% for light of 400 nm.

Additionally, the surface treated window may have a change in transmission to 670nm light within ± 5%. Specifically, the surface-treated window may have a change in transmittance for light of 670nm of 0.1% to 5%.

Further, the surface treated window may have a change in transmittance to 800nm light within ± 10%. Specifically, the transmittance of the surface-treated window for light of 800nm may vary from-10% to-1%.

Examples

Hereinafter, the present invention is explained in detail by the following examples. However, these examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1: preparation of polishing pad

1-1: preparation of the polishing layer

In a casting machine equipped with feed lines for the urethane-based prepolymer, the curing agent, the inert gas, and the reaction rate controlling agent, PUGL-450D (SKC) having an unreacted NCO content of 8.0 wt.% was charged into a prepolymer tank, and bis (4-amino-3-chlorophenyl) methane (Ishihara) was charged into a curing agent tank. A1 (tertiary amine compound, Air Product) as a reaction rate controlling agent and argon (Ar) as an inert gas were prepared.

The urethane prepolymer, the curing agent, the reaction rate controlling agent and the inert gas were fed to the mixing head via respective feed lines at a constant rate while stirring. In this case, the molar equivalent ratio of NCO groups in the urethane based prepolymer to reactive groups in the curing agent was adjusted to 1:1, and the total feed amount was maintained at a rate of 10 kg/min. Further, the feeding amount of the reaction rate controlling agent was 0.5 parts by weight based on 100 parts by weight of the urethane based prepolymer. The amount of argon fed was 20 vol.%, based on the total volume of the urethane prepolymer. The mixed raw materials were poured into a mold (width 1000mm, length 1000mm, height 3mm) and cured to obtain a sheet-like abrasive layer.

Thereafter, the surface of the polishing layer was polished to an average thickness of 2 mm.

1-2: preparation of the Window

A cake-shaped window was prepared in the same manner as in the above step 1-1, except that PUGL-500D (SKC) having an unreacted NCO content of 8.5 wt.% was used as the urethane-based prepolymer, no inert gas was supplied in the step of mixing the raw materials, and the mixed raw materials were injected into a mold (width 1000mm, length 1000mm, height 50 mm).

The pie-shaped windows were then cut and ground to make twenty sheet-like windows with an average thickness of 1.9 mm. The sheet-like window was perforated to obtain a window having a width of 20mm, a length of 60mm and a thickness of 1.9 mm.

The window and 1000 grit (1,000-grit) sandpaper was then mounted on a grinder provided with a backing layer. One side of the window was surface treated with sandpaper at a rotational speed of 300rpm and a pressure of 3.0psi for 30 seconds.

1-3: preparation of the supporting layer

The support layer (manufacturer: PTS, product name: ND-5400H, thickness: 1.1mm) was cut into a width of 1000mm and a length of 1000 mm.

1-4: preparation of polishing pad

The polishing layer of the above step 1-1 was perforated with a width of 20mm and a length of 60mm to form first through holes. The support layer of the above examples 1 to 3 was perforated with a width of 16mm and a length of 56mm to form second through holes. Then, the support layer and the abrasive layer were laminated and melt-bonded at 120 ℃ with a hot-melt film (manufacturer: SKC, product name: TF-00, average thickness: 40 μm) at a gap of 1.5 mm. A double-sided adhesive tape (manufacturer: 3M, product name: 442JS) was adhered to the other side of the support layer. And cutting and removing a portion of the double-sided adhesive tape corresponding to the second through-hole. Then, the surface-treated window of the above step 1-2 is inserted into the first through-hole with one side thereof exposed to the polishing layer. It was thermally melt-bonded at 130 ℃ and 0.5MPa for 3 minutes to prepare a polishing pad (see FIG. 1).

Comparative example 1

A polishing pad was prepared in the same manner as in example 1, except that the side surface of the window was not surface-treated.

Test example: measurement of physical Properties

The light transmittance, surface roughness and haze of the windows prepared in examples 1 and 2 and comparative example 1 were measured by the following methods, respectively. The results are shown in table 1 below.

(1) Light transmittance

The window was cut into a size of 10mm × 50mm (thickness: 2.3mm-2.4mm) and used as a sample for measuring light transmittance. The sample was placed in a glass cuvette (optical path length 10 mm. times. optical path width 10 mm. times. height 45mm) filled with ultrapure water, and light transmittance at wavelengths of 400nm, 670nm, 800nm and total light transmittance (total light transmittance) were measured using a spectrophotometer (UV-1600 PC manufactured by Shimadzu Corporation).

Then, a silicon wafer having a diameter of 300mm with a silicon oxide layer formed by a CVD process was placed in a CMP grinder. The silicon wafer is placed on a polishing pad mounted on a platen with the silicon oxide layer of the silicon wafer facing down (i.e., the non-polishing side). Thereafter, the platen was rotated at 150rpm for 20 hours, and the calcined silica polishing solution was supplied onto the polishing pad at a rate of 250mL/min, and the silica layer was polished under a polishing load of 4.0 psi. Then, the light transmittance of the surface-treated window was measured in the same manner as described above. Further, the transmittance change before and after polishing was calculated by the following formula 1.

[ formula 1]

(2) Surface roughness

The window was cut into a size of 20mm × 60mm (thickness: 2.3mm-2.4mm), and the average surface roughness (Ra) was measured using a roughness meter (manufacturer: Mitutoyo, model: SJ-400) according to ISO-1997 standard.

(3) Haze degree

The window was cut into a size of 20mm × 60mm (thickness: 2.3mm-2.4mm), and the haze was measured using a haze meter (manufacturer: Nippon Denshoku, model: NDH 5000W) having a 65D light source.

[ Table 1]

As shown in table 1, the surface-treated window of example 1 has a small change in transmittance before and after polishing, indicating that the window can effectively prevent errors that may occur in detecting an endpoint due to abrasion of the window in a CMP process. In contrast, the window of comparative example 1 had a large change in transmittance before and after polishing, indicating that an error may occur in detecting the endpoint due to the abrasion of the window during the CMP process.

< reference number >

101: polishing layer 102: surface treated window

103: adhesive layer 104: supporting layer

201: through-hole or first through-hole

202: second through hole

203: a third via.

Claims

1. A surface treated window for a polishing pad having a transmittance of 0.1% -1.5% for 400nm light and a transmittance of 4.5% -7.5% for 670nm light before polishing.

2. The surface treated window for a polishing pad according to claim 1, which has a transmittance of 5.5% -9.5% for 800nm light before polishing.

3. The surface-treated window for a polishing pad according to claim 1, having a transmittance for light of 400nm within. + -. 10%,

the change of the transmittance for 670nm light is within + -5%, and

the transmittance for 800nm light varies within + -10%,

wherein the transmittance change before and after polishing is calculated by the following formula 1:

[ formula 1]

4. The surface treated window for an abrasive pad according to claim 1, wherein the window having a width of 20mm, a length of 60mm and a thickness of 2.3mm has a haze of 85% to 98%.

5. The surface-treated window for a polishing pad according to claim 1, which has a surface roughness of 1.0 μm to 5.0 μm before polishing.

6. A polishing pad comprising the surface-treated window for a polishing pad as claimed in any one of claims 1 to 5.

7. A method of preparing a surface treated window for a polishing pad, comprising:

(1) preparing a window for a polishing pad by mixing a urethane based prepolymer, a curing agent, and a reaction rate controlling agent; and

(2) one side of the window is subjected to a surface treatment,

8. The method of preparing a surface-treated window for a polishing pad according to claim 7, wherein the surface treatment in step (2) is performed using an abrasive.

9. The method of preparing a surface-treated window for an abrasive pad according to claim 8, wherein the surface treatment is a treatment using an abrasive at a rotation speed of 100rpm to 1,000rpm and a pressure of 0.1psi to 3.0psi for 10 to 60 seconds.

10. The method of preparing a surface-treated window for a polishing pad according to claim 7, wherein the surface treatment is performed in such a manner that the surface roughness of the window is 1.0 μm to 5.0 μm.