KR100596768B1 - Chemical mechanical polishing method for semiconductor apparatus - Google Patents

Abstract

The present invention relates to a chemical mechanical polishing method of a semiconductor device, and in the related art, when different process conditions are used for each step, process instability and equipment instability can be caused, and the condition of slow removal ratio is applied in the second step. Deterioration of the uniformity and the erosion of the oxide film is severe, and when using a slurry having a different selectivity, there was a problem that two or more slurry lines are required. Therefore, the present invention deposits an insulating film on the semiconductor substrate on which the semiconductor device is formed, and forms a hole on the contact and forms a hole on the contact to form a metal wiring connected to a specific region of the semiconductor device through the contact formed on the insulating film. In the chemical mechanical polishing method of forming a barrier film on the top and depositing a tungsten film on the top and flattening the first step, the first step of removing a part of the formed tungsten film by performing chemical mechanical polishing under high pressure and high speed conditions with excellent flatness Polishing process; Through a chemical mechanical polishing method of a semiconductor device comprising a second step polishing step of polishing the tungsten film remaining on the surface of the wafer using the diluted slurry of pure water under the same conditions as the first step polishing step. It does not require a separate slurry line and uses high pressure and high speed conditions, which shortens the process time and improves flatness, so it is easy to clean after polishing, reduces over-polishing time, and improves the selectivity of tungsten. It is reduced, and there is no change in process conditions by each step, which can prevent the instability of equipment in advance.

Description

Chemical mechanical polishing method for semiconductor devices {CHEMICAL MECHANICAL POLISHING METHOD FOR SEMICONDUCTOR APPARATUS}

1 is a cross-sectional view showing a process of chemical mechanical polishing.

*** Explanation of symbols for main parts of drawing ***

1: semiconductor substrate 2: oxide film

3: contact 4: titanium

5: titanium nitride film 6: tungsten film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for chemical mechanical polishing of semiconductor devices, in particular due to the reduction of the tungsten selectivity of the slurry for chemical mechanical polishing in the two step metal chemical mechanical polishing process. The present invention relates to a chemical mechanical polishing method of a semiconductor device which is suitable for reducing oxide erosion and improving process speed.

A general chemical mechanical polishing method of tungsten is described below with reference to the procedure cross-sectional view of FIGS. 1A to 1C.

The oxide film 2 and the contact 3 are sequentially formed on the semiconductor substrate 1 on which the semiconductor device (not shown) is formed, and a part of the contact 3 is dry-etched in accordance with the region on which the metal film is to be deposited, and then the upper portion of the structure. A metal film forming step of depositing titanium (4), titanium nitride film (5), and tungsten film (6) in turn; A first step of polishing to partially remove the formed tungsten film through chemical mechanical polishing; The remaining tungsten film is subjected to a second step polishing step in which the oxide film 2 is exposed.

Referring to the procedure cross-sectional view of the general chemical mechanical polishing method of Figures 1a to 1c attached to the conventional chemical mechanical polishing method of the semiconductor device as follows.

First, as illustrated in FIG. 1A, an oxide film 2 is deposited on a semiconductor substrate 1 on which a semiconductor device (not shown) is formed, and a contact 3 connected to the semiconductor device (not shown) is formed. A part of the contact 3 is dry-etched in accordance with the region in which the metal film is to be deposited, and then titanium (4) and tungsten film (6) for improving the adhesion between the tungsten film 6 and the contact 3 on the upper surface of the structure. Titanium nitride film (5) to prevent the reaction of the) and the contact (3) is deposited, and then a tungsten film (6) is deposited on the entire upper surface by chemical vapor deposition.

Next, as shown in FIG. 1B, a part of the formed tungsten film 6 is polished and removed by using a slurry for fast polishing or by applying process conditions having a fast removal rate.

Then, as shown in FIG. 1C, polishing the remaining tungsten film 6 to expose the oxide film 2 by using a slurry for slow polishing for fine polishing or by applying a process condition having a slow removal ratio. do.

That is, when a condition having a fast removal ratio is applied in the first step polishing step, a process condition having a slow removal ratio is applied in the second step polishing step, and when using different slurries, the first step and the first step In the two-step polishing step, polishing is performed using slurries having different selectivity ratios of the tungsten film 6 to the oxide film 2.

However, the chemical mechanical polishing method of the conventional semiconductor device as described above may cause process instability and instability of equipment when different process conditions are used in each step, and in the second step, the condition of slow removal ratio is applied. As a result, uniformity deterioration and oxide erosion worsen, and there is a problem in that two or more slurry lines are required when using slurry having different selectivity.                         

The present invention was devised to solve the conventional problems as described above, and an object of the present invention is to reduce the mass production time and reduce the erosion of the oxide film by using a process condition having a fast removal ratio at all stages by using a slurry diluted in pure water. The present invention provides a method for chemical mechanical polishing of a semiconductor device that can be reduced.

 The chemical mechanical polishing method of a semiconductor device for achieving the object of the present invention as described above forms an insulating film having a contact hole for exposing a specific region of the semiconductor device on the semiconductor substrate on which the semiconductor device is formed, and on the insulating film In the chemical mechanical polishing method of forming a barrier film in contact with the exposed specific region of the semiconductor device through the contact hole and depositing and planarizing a tungsten film to fill the contact hole on the top, the deposited tungsten film is flatness A first step of polishing to remove a part of the thickness by performing chemical mechanical polishing under conditions of excellent high pressure and high speed; And a second step polishing step of polishing the remaining thickness of the tungsten film and the barrier film using pure dilution of the used slurry under the same conditions as the first step polishing step.

The chemical mechanical polishing method of the semiconductor device according to the present invention as described above will be described in detail with reference to the procedure cross-sectional view of FIGS. 1A to 1C showing the general chemical mechanical polishing procedure.

First, as illustrated in FIG. 1A, an oxide film 2 is deposited on a semiconductor substrate 1 on which a semiconductor device (not shown) is formed, a contact 3 connected to a semiconductor device (not shown) is formed, and a metal A part of the contact 3 is dry etched to have a size of 0.1 to 0.2 µm and a height of 1000 to 4000 mm in accordance with the film to be deposited, and then the adhesion between the tungsten film 6 and the contact 3 is sequentially improved on the upper surface of the structure. To form a barrier film by depositing titanium (4) for deposition and titanium nitride film (5) for preventing the reaction of the tungsten film (6) and the contact (3). The titanium nitride film 5 is deposited at about 300 to 800 mW, and in the case of vapor deposition by chemical vapor deposition, only the titanium nitride film 5 is deposited at about 300 to 800 mW.

The tungsten film 6 is deposited on the upper surface of the formed barrier film by 1000 to 10,000 kPa by chemical vapor deposition.

Then, as shown in FIG. 1B, the formed tungsten film 6 is polished with a removal ratio of 4000 kPa / min or more, the polishing pressure is 3 to 10 psi, the speed of the plate is 30 to 120 rpm, the carrier The carrier speed is 30 ~ 120rpm and the slurry flow rate is about 2/3 by chemical mechanical polishing under the condition of 100 ~ 200ml / min. At this time, when the polishing at high pressure and high speed as described above, the flatness is excellent.

Then, as shown in FIG. 1C, the tungsten film 6 remaining on the surface of the wafer is polished by diluting only the used slurry with deionized water under the same conditions as the first step polishing process. By using a mixer to dilute with pure water, the slurry used in the first step and pure water are mixed well to lower the solid concentration in the slurry, thereby improving the selectivity of tungsten to the oxide film and reducing the erosion of the oxide film. Can be suppressed.

The removal ratio, the flatness, and the selectivity of tungsten to the oxide film when using the slurry mixed with the pure water and when using the conventional slurry are shown in Table 1 below.

Process conditions Removal cost flatness Selectivity pressure speed Slurry [Å / min] [%] Selectivity of Tungsten to Oxides A condition High pressure high speed existing 3800 5.54 55.8 High pressure high speed Dilute with pure 2300 11.2 63 B condition High pressure sleaze existing 2600 12 83.3 High pressure sleaze Dilute with pure 1300 14.3 78.2 C condition Low pressure high speed existing 3000 14.9 26.8 Low pressure high speed Dilute with pure 1700 7.1 34.7

As shown in Table 1, as a result of measuring the process conditions, the slurries diluted with pure water compared to the case of using the existing slurry under the same process conditions, the removal rate of 1000 ~ 1500 Å / min under all the above conditions reduced the speed Although t is lowered, the selectivity of tungsten to the oxide film is increased under conditions A and C, which are high speed conditions, and the flatness is improved under conditions A and B using high pressure conditions.

As an example of each of the above conditions, the polishing time of 3000 tungsten was measured by chemical mechanical polishing. As described above, in the first polishing process, 2/3 of 2000 tungsten was ground and diluted with pure water. In the second polishing process using the slurry, the time taken to polish 1000 Å corresponding to 1/3 is shown in Table 2 below.

Condition First polishing process Second Grinding Process Total Time A condition 32sec 26sec 58sec B condition 46sec 46sec 92sec C condition 40sec 35sec 75sec

Table 2 shows that the fastest process time can be obtained under A condition using high pressure and high speed conditions.

In summary, the present invention described in detail above, in the planarization of the tungsten film 6 through chemical mechanical polishing, in the first polishing process, two thirds are polished under high pressure and high speed, and in the second polishing process, the first polishing is performed. When the tungsten film (6) remaining on the surface of the wafer is polished by diluting the slurry with pure water so that the solid concentration in the slurry is lowered under high pressure and high speed conditions such as the process, it can be uniformly polished at high speed. In addition, the selectivity of tungsten to the oxide film is increased, thereby reducing the erosion of the oxide film.

The chemical mechanical polishing method of the semiconductor device according to the present invention as described above does not require a separate slurry line because only one type of slurry is used, and because the slurry diluted with pure water is used under high pressure and high speed with high removal ratio, process time In addition to the shortening and improved flatness, it is easy to clean after polishing, reduce over polishing time, and improve the selectivity of tungsten to reduce erosion of oxide film, and there is no change of process condition by each step. It is effective to prevent instability of equipment.

Claims (6)

An insulating film having a contact hole for exposing a specific area of the semiconductor device is formed on the semiconductor substrate on which the semiconductor device is formed, and a barrier film is formed on the insulating film to be in contact with the exposed specific area of the semiconductor device through the contact hole. In the chemical mechanical polishing method of depositing and planarizing a tungsten film to fill the contact hole thereon, A first step polishing step of removing the thickness of the deposited tungsten film by performing chemical mechanical polishing under high pressure and high speed with excellent flatness; And a second step polishing step in which the remaining thickness of the tungsten film and the barrier film are polished by diluting the used slurry with pure water under the same conditions as the first step polishing step. Chemical mechanical polishing method. 2. The chemistry of the semiconductor device according to claim 1, wherein the tungsten film is polished at 2/3 in the first polishing step and 1/3 in the second polishing step under process conditions in which the removal rate of tungsten is 4000 mW / min or more. Mechanical polishing method. The process conditions of the chemical mechanical polishing is a polishing pressure of 3 ~ 10 psi, the polishing plate speed of 30 ~ 120 rpm, the carrier speed of 30 ~ 120rpm, slurry flow rate is 100 ~ 200ml / min A method of chemical mechanical polishing of a semiconductor device, characterized in that. The method of claim 1, wherein the contact hole formed in the lower portion of the tungsten film has a size of 0.1 to 0.2 µm and a height of 1000 to 4000 microns. 2. The semiconductor device according to claim 1, wherein the barrier layer formed under the tungsten film is formed by depositing 300-800 kW of the titanium / titanium nitride film by physical vapor deposition or 300-800 kW of the titanium nitride film by chemical vapor deposition. Chemical mechanical polishing method. A method of chemical mechanical polishing of a semiconductor device according to claim 1, wherein the tungsten film is deposited at 1000 to 10,000 kPa.

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