JP3120666B2 - Processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing apparatus. In particular, it relates to a plasma etching apparatus.

[0002]

2. Description of the Related Art In a conventional plasma etching apparatus, a seal plate made of, for example, aluminum and an upper electrode made of, for example, silicon are attached to the lower surface of the seal plate. A cavity is provided between the seal plate and the upper electrode, and a gas dispersion plate is arranged. On the other hand, a lower electrode is arranged facing the lower surface of the upper power supply at an interval. A wafer is mounted on the upper surface of the lower electrode.

In a conventional plasma etching apparatus having such a configuration, a high frequency is applied to a seal plate from a high frequency power supply. The high frequency is propagated to the upper electrode. on the other hand,
An etching gas is supplied into a cavity defined between the seal plate and the upper electrode via a gas supply hole formed in the seal plate. The etching gas supplied to the cavity is diffused by the gas dispersion plate,
The gas is ejected between the upper electrode and the lower electrode from a number of gas ejection holes formed in the upper power supply. Thereby, plasma is generated between the upper electrode and the lower electrode. The film to be processed on the wafer surface is etched by this plasma.

[0004]

However, in the conventional plasma etching apparatus, slight irregularities occur on the surface of the upper electrode which comes into contact with the seal plate. For this reason,
The contact area between the upper electrode and the seal plate to which a high frequency is applied varies depending on how the surface of the upper electrode is finished. As a result, a difference in high-frequency propagation occurs, and the state of plasma generation changes, affecting the etching characteristics. Further, if the contact between the upper electrode and the seal plate is insufficient, the uniformity of the etching rate in the wafer surface may be deteriorated.

[0005] In the manufacture of semiconductor devices, it is extremely important to uniformly process the wafer surface. It is necessary for improving the yield of semiconductor devices. Therefore, the variation in the etching rate in the wafer surface due to the poor contact between the seal plate and the upper electrode as described above is a serious problem in the manufacture of a semiconductor device.

The present invention has been made in view of the above points, and provides a processing apparatus capable of performing uniform processing on a wafer surface.

[0007]

According to the present invention, there is provided a high-frequency power supply, a conductive member to which a high frequency is applied from the high-frequency power supply, an upper electrode attached to a lower surface of the conductive member, and A conductive thin film disposed between the conductive member and the upper electrode, a lower electrode disposed at an interval facing the upper electrode, and supplying a plasma generating gas between the upper electrode and the lower electrode. And a gas supply means.

In the processing apparatus of the present invention, the conductive thin film disposed between the conductive member and the upper electrode is, for example,
It consists of conductive metals such as gold, platinum, copper and aluminum and their alloys. The thickness of the conductive thin film is, for example, in the range of 50 μm to 1 mm. The film thickness is 50 μm
If the thickness is less than 1 mm, there is a possibility that electrical conduction may be damaged. This is because the effect of improving electrical contact cannot be obtained.

The conductive thin film may be a film made of a conductive metal or a conductive alloy, or may be a coating film made of a conductive metal or a conductive alloy.
The coating film can be formed on the upper surface of the upper electrode by, for example, sputtering or CVD.

The processing apparatus of the present invention is used for processing for generating and utilizing plasma, such as plasma etching and plasma CVD.

[0011]

In the processing apparatus of the present invention, a conductive thin film is disposed between a conductive member to which a high frequency is applied and the upper electrode.
Thereby, sufficient electrical contact between the conductive member and the upper electrode can be obtained regardless of the unevenness of the surface of the upper electrode. As a result, the high frequency is favorably transmitted from the conductive member to the upper electrode.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the plasma etching apparatus of the present invention.

In FIG. 1, reference numeral 11 denotes a substantially circular upper seal plate made of aluminum. A gas supply hole 12 is formed through substantially the center of the upper seal plate. The gas supply hole 12 is connected to an end of a gas pipe 13 that supplies an etching gas from a gas supply source (not shown). A cable 14 for applying a high frequency is connected via a connector 15 to an arbitrary position on the upper surface of the upper seal plate 11. The other end of the cable 14 is connected to the high-frequency power supply unit 16.

On the other hand, on the lower surface of the upper seal plate 11, an upper electrode 17 having a plurality of gas ejection holes 17a having a concave cross section is mounted by a clamp ring 18 made of aluminum and a confinement ring 19 made of ceramics. Have been. As shown in FIG. 2, a substantially O-shaped aluminum film 20 having a thickness of 200 μm is sandwiched between the upper surface of the peripheral portion of the upper electrode 17 and the lower surface of the upper seal plate 11.

In the cavity 21 defined by the lower surface of the upper seal plate 11 and the recess of the upper electrode 17, an upper gas dispersion plate 22 and a lower second gas dispersion plate 23 made of aluminum are laminated. Is housed. The upper gas distribution plate 22 and the lower gas distribution plate 23 have a plurality of gas passage holes 22a and 23a, respectively.

The upper electrode 17 is opposed to the lower surface by 0.9
The lower electrodes 24 made of aluminum are arranged at an interval of cm. A lower seal plate 25 made of aluminum is mounted on the lower surface of the lower electrode 24. The lower electrode 24 and the lower seal plate 25 are fixed to a lower electrode end plate 42 by a focus ring 41 via an insulating ring 40 made of ceramics.

A cable 26 is connected via a connector 27 to an arbitrary position on the lower surface of the lower seal plate 25. The other end of the cable 26 is connected to the high-frequency power supply 16
It is connected to the.

On the upper surface of the lower electrode 24, a wafer 28
Is placed. The periphery of the wafer 28 is
7 is fixed by a ring-shaped clamp plate 29 provided hanging down from a peripheral edge portion.

A helium gas supply pipe 31 is connected via a joint 30 to an arbitrary position on the lower surface of the lower seal plate 25. Lower seal plate 2
5 has a through hole 32 formed therein, and helium gas is formed in a cavity 3 formed in the center of the lower electrode 24.
3. The lower electrode 24 includes
A through hole 34 for supplying helium gas is formed from the cavity 33 between the upper surface of the lower electrode 24 and the lower surface of the wafer 28.

On the periphery of the upper seal plate 11 and the clamp ring 18, a ceramic insulating ring 3 is provided.
5 is hermetically attached to the gap adjust housing 36. Gap adjust housing 3
An upper housing 37 is air-tightly connected to an outer peripheral surface of the housing 6 via a sealing plate 38. The lower housing 38 is airtightly connected to the lower end of the upper housing 37. Further, the lower end of the lower housing 38
It is connected to the lower electrode end plate 42. Thus, the upper electrode 17, the gap adjust housing 3
6, upper housing 37, sealing plate 38, lower housing 39, lower electrode end plate 42, focus ring 41, insulating ring 40 and lower electrode 24
Defines the cavity 43.

A description will be given of a case where the silicon oxide film formed on the surface of the wafer 28 is etched in the following manner in the plasma etching apparatus 10 having such a configuration.

First, an argon gas (550 SC) is supplied from a gas supply source through a gas pipe 13 and a gas supply hole 12.
CM), was fed CF ₄ gas (25 SCCM) and CHF ₃ gas (35 SCCM). Also, cavity 4
The pressure inside 3 was reduced to 500 mTorr. Further, between the lower surface of the wafer 28 and the lower electrode 24, 1
Helium gas of 0 Torr was supplied. Further, the temperatures of the upper electrode 17 and the lower electrode 24 are set to 40 ° C. and −30, respectively.
Set to ° C.

Under these conditions, a high frequency power of 1300 W was applied from the high frequency power supply section 16 to the upper electrode 17 and the lower electrode 24 to generate plasma inside the chamber 42, thereby etching the silicon oxide film on the surface of the wafer 28.
The application of the high frequency was stopped by the end point determiner or time setting, and the etching was terminated.

The relationship between the distance from the center of the wafer and the etching rate at that point is shown in the characteristic diagram of FIG.

Further, the aluminum film 20 is placed on the upper surface of the peripheral portion of the upper electrode 17 and the upper seal plate 11.
In a plasma etching apparatus of a comparative example having the same configuration as that of the above-described plasma etching apparatus 10 except that the silicon oxide film was not disposed between the lower surfaces, the same silicon oxide film as described above was etched. The relationship between the distance from the wafer center and the etching rate at that point is shown in the characteristic diagram of FIG.

The plasma etching apparatus 10 of the present invention
Since the aluminum film 20 is disposed between the upper surface of the peripheral portion of the upper electrode 17 and the lower surface of the upper seal plate 11, sufficient electrical contact between the upper electrode 17 and the upper seal plate 11 is ensured. Figure 3
As shown in (A), the etching rate is uniform at about 5000 Å (A) / min. The uniformity was 1.2%.

On the other hand, in the plasma etching apparatus of the comparative example, the upper electrode 17 has irregularities on the upper end surface of the peripheral portion thereof, and the electrical contact between the upper electrode 17 and the upper seal plate 11 is not sufficient. As shown in FIG. 3 (B), the etching rate is largely different between the peripheral portion and the central portion of the wafer, and is non-uniform. The uniformity was 4.6%.

As is apparent from the above description, the plasma etching apparatus 10 according to the present invention provides the electrical contact between the upper electrode 17 and the upper seal plate 11 irrespective of the finishing condition of the surface of the upper electrode 17. Can be sufficiently secured, and the etching rate in the wafer surface can be made uniform. As a result, the yield of the semiconductor device can be improved.

In the embodiment of the present invention, the case where the aluminum film 20 is disposed between the upper surface of the peripheral portion of the upper electrode 17 and the lower surface of the upper seal plate 11 has been described. An aluminum film having a thickness of 10 μm can be formed on the upper surface by sputtering. Also in this case, the etching rate in the wafer surface could be made uniform as in the above-described embodiment.

[0031]

As is apparent from the above description, the processing apparatus of the present invention is capable of reducing the conductive member by disposing a conductive thin film between the conductive member to which a high frequency is applied and the surface of the upper electrode. By sufficiently transmitting the high frequency to the upper electrode, uniform processing can be performed on the entire surface of the target film. As a result, the yield of the semiconductor device can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a plasma etching apparatus of the present invention.

FIG. 2 is a sectional view showing a main part of the plasma etching apparatus of the first embodiment.

FIGS. 3A and 3B are cross-sectional views showing a relationship between a distance from a wafer center and an etching rate in etching by the plasma etching apparatus of the present invention and a comparative example.

DESCRIPTION OF SYMBOLS 10: plasma etching apparatus, 11: upper seal plate, 16: high frequency power supply unit, 17: upper power supply, 20: aluminum film, 24: lower electrode, 25: lower seal plate, 28: wafer.

Claims (2)

(57) [Claims] 1. A high-frequency power supply, a conductive member to which a high frequency is applied from the high-frequency power supply, an upper electrode attached to a lower surface of the conductive member, and a portion between the conductive member and the upper electrode. A conductive thin film disposed on the lower electrode disposed at an interval facing the upper electrode,
A gas supply means for supplying a plasma generating gas between the upper electrode and the lower electrode. 2. The processing apparatus according to claim 1, wherein the processing apparatus is for plasma etching.