JPH07201822A - Dry etching device - Google Patents

Abstract

PURPOSE:To provide uniform etching speed and etched form on a surface of a semiconductor substrate. CONSTITUTION:Dividing either or both of an upper electrode 5 and a lower electrode 7 into blocks and controlling the temperature of each block independently, a uniform etching speed on the surface of the semiconductor substrate is provided. The elimination of the difference of the etched form on the surface is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus for semiconductor manufacturing.

[0002]

2. Description of the Related Art FIG. 5 shows a block diagram of a conventional dry etching apparatus. The conventional dry etching apparatus includes a vacuum container 11 for etching a semiconductor substrate 6, an upper electrode 5 and a lower electrode 7 provided therein, and a gas source 1.
A gas flow rate control unit 2 for controlling the flow rate from the chamber, temperature control units 3, 4 for the upper and lower electrodes, a pressure control unit 9 for controlling the pressure in the vacuum container 11, and an exhaust system 10. .

In the vacuum container 11, various etching gases whose gas flow rate control unit 2 has controlled the constant flow rate are mixed. At the same time, the vacuum container 11 is kept at a constant pressure by the pressure control unit 9. Vacuum container 1 kept at constant stress
A high-frequency voltage is applied between the upper electrode 5 and the lower electrode 7 while a dry etching gas having a constant flow rate is flown in the plasma generating chamber 1 to generate plasma, and the semiconductor substrate 6 on the lower electrode 7 is
To etch.

The etching characteristics of the semiconductor substrate 6 on the lower electrode 7 (etching speed, in-plane distribution of etching speed on the substrate, selectivity by etching film quality, etching shape, etc.) It is affected by the pressure, the flow rate of the etching gas and its flow rate, the high frequency voltage, and the temperature of the upper electrode 5 and the lower electrode 7, so that the most suitable etching characteristics can be obtained by arbitrarily changing these depending on the quality of the film to be etched. Is possible.

[0005]

In this conventional dry etching apparatus, since the temperature of a part of the upper electrode 5 and the lower electrode 7 is controlled as the temperature of the entire electrode, the temperature control can be partially performed. could not. Therefore, when there is a difference in the temperature distribution within the electrode surface, the etching characteristics,
In particular, there is a problem that the distribution of the etching speed within the surface of the semiconductor substrate (hereinafter referred to as etching uniformity) is deteriorated and the etching shape may have an in-plane difference.

[0006]

A dry etching apparatus according to the present invention comprises an upper electrode and a lower electrode divided into a plurality of blocks whose temperatures can be independently controlled.

[0007]

The present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention. FIG. 1A is a configuration diagram and FIG. 1B is a plan view of a lower electrode. The lower electrode 7 is concentrically shaped 7 via the heat insulating portion 8.
The temperature control unit (for lower electrode) 3 is divided into three blocks A, 7B and 7C, and each block has independent temperature control units 3A, 3B and 3C. By setting each block to an appropriate temperature, for example, when the etching uniformity in the plane of the semiconductor substrate 6 is poor,
This can be improved. Further, even when there is a difference in the shape of etching in the plane of the substrate, this can be reduced.

2A and 2B are views showing a second embodiment of the present invention. FIG. 2A is a configuration diagram, FIG. 2B is a plan view of the lower electrode 7,
FIG. 6C is a plan view of the upper electrode 5. In the second embodiment, the temperature of the lower electrode 7 is controlled for each block in the same manner as in the first embodiment, and at the same time, the upper electrode 5 also has the temperature control portion (for the upper electrode) 4 formed into blocks 4A, 4B, 4C. Has a function of setting an appropriate temperature for each block. By simultaneously controlling the temperature of the lower electrode 7 and the upper electrode 5 for each block, it is possible to further improve the in-plane uniformity of etching and the in-plane shape difference of etching.

FIG. 3 is a diagram for comparing in-plane uniformity of etching. FIG. 3A shows a conventional example, the first embodiment (the lower electrode is divided), and the second embodiment (both the upper electrode and the lower electrode). It is a graph comparing each of the two). Further, FIG. 3B is a diagram showing measurement points on the semiconductor substrate.
A single wafer type narrow gap reactive ion etching apparatus was used for dry etching, and the gas was Ar: 400 sccm,
A mixed gas of CF ₄ : 20 sccm and CHF ₃ : 20 sccm was used. Pressure during etching is 850 mTorr
And the RF power was 850W. As the film to be etched, a silicon oxide film having a thickness of 0.7 μm grown on a semiconductor substrate having a diameter of 6 inches was used. The etching time is
It took about half the time to etch the 0.7 μm thick silicon oxide film. The temperatures of the upper electrode and the lower electrode of the conventional example were 40 ° C. and −15 ° C., respectively. In the first embodiment, the upper electrode has a temperature of 40 ° C. and the lower electrode has a central portion of 7 A of −15.
C., 7B was -10.degree. C., and 7C was -5.degree. In the second embodiment, the upper electrode is 5 A at 35 ° C. and 5 B is 40 B from the center.
C. and 5 C were set to 45.degree. C., and the lower electrode was set to the same temperature as in the first embodiment. The etching speed is measured at nine measurement points in FIG. 3B, the in-plane minimum value of the etching speed is subtracted from the in-plane minimum value, and the result is divided by the average value of the nine in-plane values. Thus, the in-plane uniformity (%) of etching was calculated. As shown in FIG. 3 (A), the in-plane uniformity of etching was 8.1% in the etching of the conventional example, but was 4.5% in the first example and was 3.3% in the second example.
It was reduced to 3%.

FIG. 4 is a diagram comparing etching shapes at measurement points. FIGS. 4A and 4B are comparisons of a central portion and a peripheral portion in the case of the conventional example, and FIGS. 4C and 4D. Is the first
Comparison of the central part and the peripheral part in the case of the embodiment, FIG.
FIG. 6F is a cross-sectional view showing a comparison between the central portion and the peripheral portion in the case of the second embodiment. The sample used is one having a silicon oxide film 13 of 0.7 μm formed on a semiconductor substrate 12 having a diameter of 6 inches, a photoresist film applied thereon, and a contact having a diameter of 0.6 μm formed in an optical exposure apparatus. The etching was performed under the above conditions (gas is Ar: 400 sc).
cm, CF ₄ : 20 sccm, CHF ₃ : 20 scc
m, pressure 850 mTorr, RF power 850 W)
The etching time was twice as long as the time for etching the substrate and then etching the substrate.

As shown in FIG. 4, in the conventional etching, there was a difference of 4 ° in the angle of the bottom of the contact between the central portion (within a radius of 35 mm) of the semiconductor substrate and the peripheral portion (closer to 10 mm from the edge of the substrate). . In the first embodiment, the difference is 1 °
In the second embodiment, the same contact shape was obtained in the central portion and the peripheral portion of the semiconductor substrate.

[0013]

As described above, according to the present invention, the upper electrode and the lower electrode are divided into blocks and the temperature can be controlled for each block. Therefore, the in-plane uniformity of etching can be improved and the surface of the etching shape can be improved. It has the effect of eliminating the internal difference. Therefore, the product yield and quality can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, in which FIG. 1A is a configuration diagram and FIG. 1B is a plan view of a lower electrode.

2A and 2B are views showing a second embodiment of the present invention, wherein FIG. 2A is a configuration diagram, FIG. 2B is a plan view of a lower electrode, and FIG. 2C is a plan view of an upper electrode. .

3A and 3B are diagrams for comparing in-plane uniformity of etching. FIG. 3A is a graph comparing the conventional example with the first embodiment and the second embodiment, and FIG. 3B is a semiconductor substrate. It is a figure which shows the measurement point of.

4A and 4B are diagrams comparing etching shapes of measurement points in a central portion and a peripheral portion of a substrate. FIGS. 4A and 4B show a conventional example, FIGS. 4C and 4D show a first embodiment, The same figure (E),
(F) is a sectional view showing a second embodiment.

FIG. 5 is a configuration diagram of a conventional dry etching apparatus.

[Explanation of symbols]

 1 gas source 2 gas flow rate control unit 3, 3A, 3B, 3C temperature control unit (for lower electrode) 4, 4A, 4B, 4C temperature control unit (for upper electrode) 5, 5A, 5B, 5C upper electrode 6 semiconductor substrate 7, 7A, 7B, 7C Lower electrode 8 Heat insulation part 9 Pressure control part 10 Exhaust system 11 Vacuum container 12 Semiconductor substrate 13 Silicon oxide film

Claims (1)

[Claims] 1. A dry etching apparatus having a pair of upper and lower electrodes in a vacuum container and applying a high-frequency voltage between the electrodes to etch a semiconductor substrate in the vacuum container. The dry etching apparatus is characterized in that the dry etching apparatus is divided into blocks and each of the blocks is provided with a temperature control unit that controls the temperature independently.