KR20100079199A

KR20100079199A - Method and apparatus for chemical mechanical polishing

Info

Publication number: KR20100079199A
Application number: KR1020080137615A
Authority: KR
Inventors: 김효상
Original assignee: 주식회사 동부하이텍
Priority date: 2008-12-30
Filing date: 2008-12-30
Publication date: 2010-07-08

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical mechanical polishing apparatus and method, wherein the polishing rate is varied according to the thickness difference between the center region and the edge region of the wafer, thereby minimizing the thickness difference between the center region and the edge region. There is an advantage of preventing in advance any defects that may have occurred.

Description

Chemical mechanical polishing apparatus and method {METHOD AND APPARATUS FOR CHEMICAL MECHANICAL POLISHING}

The present invention relates to a chemical mechanical polishing apparatus and method, and more particularly, to a chemical mechanical polishing apparatus and method for varying the polishing rate according to the thickness difference between the center region and the edge region of the wafer.

As is well known, in order to secure photo margins and minimize wiring lengths with high integration of semiconductor devices, a planarization technique of a lower layer is required, and a chemical mechanical polishing process is one of such planarization techniques.

The chemical mechanical polishing process has the advantage of being able to achieve a wide range of global planarization and low temperature planarization which cannot be achieved by the reflow process or the etch-back process. In recent years, the application of the polysilicon film for etching the bit line contact plug and the storage node contact plug in the self aligned contact process is increasing.

A chemical mechanical polishing apparatus for performing a chemical mechanical polishing process includes a polishing table (platen) having a polishing pad (elastic polishing cloth) on its surface, and a polishing liquid (a polishing liquid) on the polishing pad when wafer polishing is performed. a polishing liquid supply for supplying slurry, a polishing head (wafer carrier) for pressing and supporting a wafer on a polishing table including a polishing pad, and a pad conditioner for regenerating the polishing surface of the polishing pad ( pad conditioner).

According to such a chemical mechanical polishing apparatus, a polishing liquid is supplied while a wafer is brought into contact with a surface of a polishing pad to chemically react with the surface of the wafer, and the polishing table to which the polishing pad is attached and the polishing head fixing the wafer are physically moved. This planarizes the uneven portion of the wafer surface. That is, the wafer is polished by the polishing pad and the slurry as the polishing table performs a simple rotational movement and the polishing head is pressed at a constant pressure while simultaneously rotating and swinging.

On the other hand, the polishing flatness by the chemical mechanical polishing apparatus is an important factor that greatly affects the yield of the device. For example, in the case where the insulating film of the edge region is deposited relatively thinner than the central region of the wafer, after chemical mechanical polishing, the insulating film of the edge region may become too thin and cause defects. In the case of relatively thick deposition, after the chemical mechanical polishing, the insulating layer in the edge region is excessively thick, so that the etching may be unstable during the contact or via process connecting the device and the wiring or the wiring and the wiring, thereby causing a defect.

As described above, according to the chemical mechanical polishing process according to the related art, there is a problem that a semiconductor device may be defective after chemical mechanical polishing due to the difference in thickness between the center region and the edge region of the wafer.

The present invention has been proposed to solve the problems of the prior art, and provides a chemical mechanical polishing apparatus and method for varying the polishing rate according to the thickness difference between the center region and the edge region of the wafer.

In one aspect of the present invention, a chemical mechanical polishing apparatus includes a measuring unit capable of measuring a thickness of a center region and an edge region of a wafer, and comparing the thickness measurement values of the center region and the edge region by the measuring unit. And a controller capable of determining a polishing rate for the center region and the edge region, and a polishing portion for polishing the surface of the wafer according to the polishing rate determined by the controller.

Here, the controller may determine the polishing rate according to a comparison result with a preset reference value after calculating a difference value between the average thickness of the center region and the average thickness of the edge region.

In another aspect of the present invention, a chemical mechanical polishing method includes measuring a thickness of a center region and an edge region of a wafer, and comparing the thickness measurement values of the center region and the edge region to determine the thickness of the center region and the edge region. Determining a polishing rate and polishing the surface of the wafer according to the determined polishing rate.

The determining may include calculating a difference value between the average thickness of the center region and the average thickness of the edge region, and calculating the polishing rate according to a result of comparing the calculated difference value with a preset reference value. Determining.

According to the present invention, by varying the polishing rate according to the thickness difference between the center region and the edge region of the wafer, it is possible to minimize the thickness difference between the center region and the edge region, thereby eliminating defects that may have occurred due to the difference in thickness of each region of the wafer. It is effective to prevent in advance.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a schematic diagram showing a chemical mechanical polishing apparatus according to an embodiment of the present invention.

As shown therein, the chemical mechanical polishing apparatus 100 of the present invention includes a measuring unit 110, a control unit (not shown), a polishing unit 120, a polishing liquid supply unit (not shown), a cleaning unit 130, It is configured to include a transfer unit 140 and the like.

The measuring unit 110 measures the thicknesses of the center region and the edge region of the wafer and provides them to the controller.

The controller compares the thickness measurement values of the center region and the edge region of the wafer by the measuring unit 110 to determine the polishing rate for the center region and the edge region of the wafer. First, the difference between the average thickness of the center region and the average thickness of the edge region is calculated, and the difference between the calculated center region and the edge region is compared with the preset reference value. The polishing rate for each is determined.

The polishing unit 120 polishes the surface of the wafer using a polishing pad according to the polishing rate determined by the controller.

The polishing liquid supply unit supplies the polishing liquid to the polishing pad during polishing of the wafer by the polishing unit 120.

The cleaning unit 130 removes the polishing liquid and foreign matter remaining on the wafer polished by the polishing unit 120.

The transfer unit 140 transfers the wafer under the control of the controller and loads the wafer into the measurement unit 110, the polishing unit 120, and the cleaning unit 130, or the measuring unit 110, the polishing unit 120, and the cleaning unit 130. Unload from).

Reference numeral 150 in the figure indicates an unload port through which the cleaned wafer is discharged to the outside by the transfer unit 140.

2 is a flowchart illustrating a chemical mechanical polishing method according to an embodiment of the present invention.

As described above, the chemical mechanical polishing method of the present invention includes measuring the thickness of the center region and the edge region of the wafer (S210), comparing the thickness measurement values of the center region and the edge region, Determining the polishing rate (S220, S231, S233, S235), polishing the surface of the wafer according to the determined polishing rate (S240), and removing the polishing liquid and foreign matter remaining on the polished wafer ( S250) and the step of discharging to the outside after measuring the thickness of the cleaned wafer (S260) and the like. In determining the polishing rate, after calculating the difference between the average thickness of the center region and the average thickness of the edge region, the polishing rate for the center region and the edge region is calculated according to the comparison result between the calculated difference value and the preset reference value. Decide

1 and 2 illustrate components that are deemed necessary for the explanation and understanding of the apparatus and method for chemical mechanical polishing according to an embodiment of the present invention, but other components may be included. For example, it may include a pad conditioner for regenerating the polishing surface of the polishing pad. In addition, according to the embodiment, the polishing liquid supply unit is divided into separate polishing liquid supply apparatuses, the cleaning unit 130 is divided into separate cleaning apparatuses, and the transfer unit 140 is divided into separate transfer apparatuses, and the like. The chemical mechanical polishing apparatus can be implemented by excluding the corresponding components, and likewise can be implemented by excluding the processes performed by the corresponding components.

The chemical mechanical polishing method by the chemical mechanical polishing apparatus according to the embodiment of the present invention configured as described above will be described in more detail with reference to FIGS. 1 and 2.

First, under a control of a controller (not shown), the transfer unit 140 transfers a wafer and loads the wafer into the measurement unit 110.

The measuring unit 110 transmits the thickness measurement value measured by measuring the thicknesses of the center region and the edge region of the loaded wafer (S210).

The method of measuring the thickness of the wafer by the measurement unit 110 may use a method of measuring the thickness of the wafer to determine the completion time of the surface polishing. For example, the thickness of the wafer (or insulating film) can be measured by irradiating a laser beam onto the wafer surface film layer to track the change in the reflected light intensity over time.

The controller compares the thickness measurement values of the center region and the edge region of the wafer to determine the polishing rate for the center region and the edge region. In this case, after calculating the difference between the average thickness of the center region and the average thickness of the edge region, the polishing rate for the center region and the edge region is determined according to the comparison result (S220) between the calculated difference value and the preset reference value. do. For example, when the edge area is thinner than the center area by more than the reference value, the polishing rate is determined to polish the center area more than the edge area (S231), and when the edge area and the center area are similar in thickness, the edge area and the center area are similar. The polishing rate is determined to polish the regions equally (S233), and when the edge region is thicker than the central region by more than the reference value, each polishing rate is determined to polish the edge region more than the central region (S235).

Under the control of the controller, when the transfer unit 140 unloads the wafer from the measurement unit 110 and loads the wafer into the polishing unit 120, the polishing unit 120 polishes the surface of the wafer according to the polishing rate determined by the control unit (S240). ). That is, according to the determination of steps S231, S233, and S235, the center region is polished more than the edge region, the edge region and the center region are polished equally, or the edge region is polished more than the center region.

When the polishing process by the polishing unit 120 is finished, the transfer unit 140 transfers the wafer from the polishing unit 120 to the cleaning unit 130. Although the description thereof is omitted, the thickness of the wafer is measured to determine the completion time of the surface polishing, and the polishing process by the polishing unit 120 is finished according to the measurement result.

The cleaning unit 130 removes the polishing liquid and foreign matter remaining on the wafer when the wafer is loaded (S250), and when the wafer is cleaned is loaded on the measuring unit 110 by the transfer unit 140, the measuring unit 110 Measures the thickness of the wafer again and transmits it to the controller, and the controller determines whether the wafer is polished to the desired thickness (S260).

Finally, when all processes are completed, the transfer unit 140 transfers the wafer to the outside through the unloading port 150.

It has been described so far limited to some embodiments of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

1 is a schematic diagram showing a chemical mechanical polishing apparatus according to an embodiment of the present invention,

2 is a flow chart for explaining a chemical mechanical polishing method according to an embodiment of the present invention.

100: chemical mechanical polishing device 110: measuring unit

120: grinding unit 130: cleaning unit

140: transfer unit 150: unloading port

Claims

A measuring unit capable of measuring the thickness of the center region and the edge region of the wafer,

A control unit for comparing the thickness measurement values of the center area and the edge area by the measurement unit to determine a polishing rate for the center area and the edge area;

A polishing unit capable of polishing the surface of the wafer according to the polishing rate determined by the control unit

Chemical mechanical polishing apparatus comprising a.

The method of claim 1,

The control unit may calculate the difference value between the average thickness of the center region and the average thickness of the edge region and determine the polishing rate according to a comparison result with a preset reference value.

Chemical mechanical polishing device.

Measuring the thickness of the center region and the edge region of the wafer,

Comparing the thickness measurement values of the center area and the edge area to determine a polishing rate for the center area and the edge area;

Polishing the surface of the wafer according to the determined polishing rate

Chemical mechanical polishing method comprising a.

The method of claim 3, wherein

The determining step,

Calculating a difference value between the average thickness of the center region and the average thickness of the edge region;

Determining the polishing rate according to a result of comparing the calculated difference value with a preset reference value

Chemical mechanical polishing method comprising a.