JPH10326772A - Dry etching equipment - Google Patents

Abstract

(57) Abstract: A dry etching apparatus capable of uniformly etching the entire surface of a substrate to be processed is provided. A substrate W to be processed such as a semiconductor wafer is placed on a lower electrode 3 and a processing gas is introduced into a decompression tank 1.
In a dry etching apparatus that generates plasma by applying an AC electric field between the two electrodes to etch the surface of the substrate W to be processed, the lower electrode 3 is divided into a plurality of partial electrodes 3a to 3c that are insulated from each other. A control device 4 for controlling the frequency of an AC electric field applied between the upper electrode 2 and each of the partial electrodes 3a to 3c is provided. The plasma state in the vicinity of the surface of the substrate W to be processed is determined by each of the partial electrodes 3a to 3c.
Can be changed for each region where the etching process is performed, so that the plasma state of the portion where the etching rate is apt to decrease is changed to a higher energy state than other portions, and the substrate W to be processed is
Can be uniformly etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-wafer dry etching apparatus, and more particularly to a dry etching apparatus capable of uniformly etching a substrate to be processed.

[0002]

2. Description of the Related Art FIG. 2 is a schematic diagram showing an example of a conventional dry etching apparatus. As shown in the figure, a conventional dry etching apparatus 20 includes an upper electrode 2 in a decompression tank 21.
2 and the lower electrode 23 are opposed to each other, the upper electrode 22 is grounded, and the lower electrode 23 is connected to a high frequency power supply 28. The decompression tank 21 introduces a reaction gas (processing gas) such as a fluorinated gas into the tank from a gas introduction port 25 provided at the center of the upper electrode 22 while exhausting the inside of the tank from an exhaust port 24 provided at the bottom. I can do it. A substrate 26 such as a semiconductor substrate is set on the lower electrode 23 for each process. A clamp 27 is provided around the lower electrode 23, and a displacement of the substrate 26 during processing is prevented by pressing a peripheral portion of the substrate 26 with the clamp 27. The operation of the dry etching apparatus 20 is as follows. First, the object 2 to be processed is placed on the lower electrode 23.
6 is placed and fixed by the clamp 27, and then the inside of the decompression tank 21 is exhausted. When the inside of the decompression tank 21 reaches a predetermined degree of vacuum,
A reaction gas is introduced, and a high-frequency power supply 28 is operated to apply a high-frequency electric field between the upper electrode 22 and the lower electrode 23. Thereby, the reaction gas introduced into the decompression tank 21 is ionized, and the ions of the reaction gas etch the surfaces of the plurality of objects 26 on the lower electrode 23.

[0003]

However, in the above-described conventional dry etching apparatus, during processing, the substrate 26 to be processed is not used.
Is held down by the clamp 27, the etching rate of the peripheral portion of the surface of the substrate 26 to be processed is lower than that of the other portions. Although the degree of this decrease depends on the etching conditions, in a conventional dry etching apparatus,
Since there is no means for partially changing the plasma state near the surface of the substrate 26 to be processed, it has been difficult to uniformly etch the entire surface. An object of the present invention is to provide a dry etching apparatus which can solve the above-mentioned disadvantages of the conventional technique and can uniformly etch the entire surface of a substrate to be processed.

[0004]

In order to solve the above-mentioned problems, the present invention comprises an upper electrode and a lower electrode which are arranged in a decompression tank so as to face each other, and a processing object such as a semiconductor wafer is placed on the lower electrode. After the substrate is placed and a processing gas is introduced into the decompression tank, a plasma is generated by applying an AC electric field between the two electrodes to generate plasma, and the surface of the substrate to be processed is etched. It is characterized in that it is provided with a control device which divides into a plurality of partial electrodes which are insulated from each other and controls the frequency of an AC electric field applied between the partial electrodes for each partial electrode. According to the dry etching apparatus configured as described above, by controlling the frequency of the AC electric field applied between the upper electrode and the lower electrode for each partial electrode of the lower electrode, the frequency of the vicinity of the surface of the substrate to be processed can be improved. Since the plasma state can be changed for each region where each partial electrode acts, the plasma state of the part where the etching rate is apt to decrease is made higher in energy state than other parts, and the entire surface of the substrate to be processed is changed. Can be uniformly etched.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. FIG. 1A is a side sectional view showing an example of an embodiment of a dry etching apparatus according to the present invention, and FIG. 1B is a plan view of a main part of the dry etching apparatus shown in FIG. The dry etching apparatus 100 performs an etching process on the surface of a substantially circular substrate W to be processed such as a semiconductor substrate. As shown in FIG. 1A, an upper electrode (anode) is provided in a decompression tank 1. 2
And the lower electrode 3 on which the substrate to be processed W is placed are arranged to face each other. The upper electrode 2 and the lower electrode 3 are disk-shaped electrodes having a slightly larger diameter than the substrate W to be processed and having substantially the same shape and size. The upper electrode 2 is grounded by a ground line 12. The lower electrode 3 is connected to a high-frequency power source 5 via a control device 4.
And a low-frequency power supply 6. In the decompression tank 1, a reaction gas (processing gas) such as a fluoride gas is introduced into the tank from a gas inlet 8 provided in the center of the upper electrode 2 while exhausting the inside of the tank from an exhaust port 7 provided at the bottom. I can do it. One substrate W to be processed is set on the lower electrode 3 for one processing. Further, a clamp 9 is provided around the lower electrode 3 as in the related art, and the displacement of the substrate W during processing can be prevented by pressing the peripheral edge of the substrate W with the clamp 9. . As shown in FIG. 1B, the lower electrode 3 includes an innermost partial electrode 3a and an intermediate partial electrode 3b along the radial direction.
And the outermost partial electrode 3c, and are electrically insulated by an insulating material 10 between the partial electrodes 3a and 3b and between the partial electrodes 3b and 3c. Each partial electrode 3
a, 3b, and 3c are separate power supply lines 11 respectively.
a, 11b, and 11c are connected to the control device 4. Note that aluminum is used for the partial electrodes 3a, 3b, and 3c, and alumina and alumite are used for the insulating material 10. The control device 4 controls each of the power supply lines 11a, 11
b and 11 c and a function of selectively connecting the high frequency power supply 5 or the low frequency power supply 6. The frequency f1 of the high frequency power supply 5 is 13.56 MHz, and the frequency f2 of the low frequency power supply 6
Is about 500 MHz or less.

Next, the operation of the present embodiment will be described. After the substrate to be processed W is placed on the lower electrode 3 and the substrate to be processed W is fixed by the clamp 9, the evacuation of the decompression tank 1 is started by a vacuum pump (not shown). When the evacuation in the decompression tank 1 is completed, an etching gas is introduced into the decompression tank 1, and an AC electric field is applied between the upper and lower electrodes 2 and 3,
Plasma of an etching gas is generated in the decompression tank 1.
The ions in the plasma perform an etching process on the surface of the target substrate W placed on the lower electrode 3.
During this etching process, the control device 4 controls the power supply line 11c connected to the outermost partial electrode 3c of the lower electrode 3.
Are connected to the high-frequency power supply 5, and the power supply line 11 a connected to the innermost partial electrode 3 a and the power supply line 11 b connected to the intermediate partial electrode 3 b are connected to the low-frequency power supply 6. Thus, the etching process is performed while maintaining the plasma state near the peripheral edge of the processing target substrate W, which is the part where the etching rate is apt to decrease, at a higher energy state than other parts. Therefore, according to the dry etching apparatus of this embodiment, the processing is performed while uniformly controlling the etching rate in the plane of the substrate W to be processed.
The depth of the etching grooves and the like formed on the surface of the substrate can be made uniform on the same substrate. Each of the partial electrodes 3a, 3b, and 3c of the lower electrode 3, the high-frequency power supply 5, and the low-frequency power supply 6
The connection form can be appropriately changed according to the etching conditions. Further, in the above example, the case where the lower electrode 3 is divided into three is described. However, the invention is not limited thereto, and the lower electrode 3 may be subdivided into four or more. In this case, if more types of power supplies having different frequencies are prepared, it is possible to finely control the plasma state near the surface of the substrate W to be processed, for example, by slightly changing the power frequency supplied to each partial electrode. .

[0007]

As described above, according to the dry etching apparatus of the present invention, the frequency of the AC electric field applied between the upper electrode and the lower electrode is controlled for each partial electrode of the lower electrode. Since the plasma state in the vicinity of the surface of the substrate to be processed can be changed for each region where each partial electrode acts, the plasma state in a portion where the etching rate is apt to be reduced is changed to a higher energy state than other portions. In addition, the entire surface of the substrate to be processed can be uniformly etched.

[Brief description of the drawings]

1A is a side sectional view showing an example of an embodiment of a dry etching apparatus according to the present invention, and FIG. 1B is a plan view of a main part of the dry etching apparatus shown in FIG.

FIG. 2 is a side sectional view showing an example of a conventional dry etching apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Decompression tank, 2 Upper electrode, 3 Lower electrode, 3a partial electrode, 3b partial electrode, 3c partial electrode, 4 Control device, 5 High frequency power supply, 6 Low frequency power supply, 7 Exhaust port, 8
Gas inlet, 9 clamp, 10 insulating material, 11a
Power supply line, 11b power supply line, 11c power supply line, 12 ground line, 100 dry etching device, W
Substrate to be processed.

Claims (1)

[Claims] An upper electrode and a lower electrode are provided in a decompression tank so as to face each other, a substrate to be processed is placed on the lower electrode, and a processing gas is introduced into the decompression tank. In a dry etching apparatus for generating plasma by applying an AC electric field therebetween to etch a surface of a substrate to be processed, the lower electrode is divided into a plurality of partial electrodes insulated from each other, and the lower electrode is separated from the upper electrode. A dry etching apparatus comprising a control device for controlling the frequency of an AC electric field applied to each of the partial electrodes.