JPS62111431A - Dry etching device - Google Patents

Abstract

PURPOSE:To obtain the dry etching device capable of enhancing the etching rate of a gate material or increasing the selectivity with a base film by providing a sample electrode with two systems of grounded circuits. CONSTITUTION:A treatment gas is introduced in a treatment chamber 1 and the air in the chamber is exhausted to reduce the pressure to a predetermined value. To a sample electrode 2 in the processing chamber 1, a grounded circuit 6 which is grounded directly and a grounded circuit 7 grounded through a coil 7a are provided and connected through a switch 8. An opposite electrode 3 is connected to a high-frequency power source 5 through a matching device 4. A sample 9 made of an Si substrate coated with a base film of SiO2 and further a gate material of polysilicon is etched. As for the etching rate of the polysilicon, the etching rate 17 of the grounded circuit 7 becomes higher than the etching rate 15 of the grounded circuit 6 and as for the selectivity of the polysilicon and SiO2, the selectivity 16 of the grounded circuit 6 becomes larger than the selectivity 18 of the grounded circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a dry etching apparatus, and particularly to a dry etching apparatus suitable for a type using an anode bond.

[Background of the invention]

The conventional bag has one parallel plate, as described in, for example, Japanese Patent Application Laid-Open No. 59-96277. The polar type dry etching equipment is equipped with a power supply system using a 7-node doubling method and a power supply system using a cathode doubling method, making it possible to switch between the two types of power vubbling methods as desired, and thereby making it possible to perform chemical etching. We made it possible to perform strong isotropic etching and anisotropic etching with a strong sputtering effect, and just before the end of etching, we switched to an anode coupling method to reduce damage to the underlying material through isotropic etching. There is something.

However, according to this method, there is a problem that switching between connecting each electrode of the parallel plate to the electrode and grounding becomes complicated.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry etching apparatus which is capable of increasing the etching rate of the gate material and increasing the etching selectivity with respect to the underlying film in an anode bonding method.

[Overview of Jimu Ming]

The present invention relates to a dry etching/I-etching apparatus having a processing chamber which is supplied with a processing gas and is evacuated to a predetermined pressure, a sample electrode on which a sample is placed, and a counter electrode facing the sample electrode. A high-frequency power source that applies a high-frequency voltage is connected to the opposite electrode via a matching box, and the grounding circuit is connected to a grounding circuit that is directly grounded to the sample'@pole and a grounding circuit that is grounded via means for loading impedance. 1) The sample 1! electrode has two grounding methods, and the etching characteristics of each grounding method are utilized to create a grounding circuit with a high etching speed from the start of etching to just etching. When performing over-etching, the circuit is designed so that it can be etched by switching to a grounding circuit with a larger selection ratio.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows a block diagram of a dry etching apparatus.

Reference numeral 1 denotes a processing chamber to which a processing gas is supplied and evacuated to a predetermined pressure by a gas supply device and an exhaust device (not shown).

Reference numeral 2 denotes a sample electrode provided in the processing chamber 1 and on which the sample 9 is placed. The sample electrode 2 includes a grounding circuit 6 that is directly grounded using a material with low impedance, such as a copper plate or copper wire;
Two grounding circuits are provided, including a grounding circuit 7 that is grounded through a means for applying impedance, for example, a coil 7a, and connected through a switching means 1, for example, a changeover switch 8. 3 is provided in the processing chamber 1, and sample 1! A counter electrode provided opposite to pole 2. The counter electrode 3 is connected to a high frequency power source 5 via a matching box 4.

In the above configuration, in this case, 11! below 5102 on 81 substrate! l! coated with poly-8i film and coated with poly-8i
An etching experiment was conducted on Sample 9, which was coated with a gate material and a mask was coated thereon. What are the kneeching conditions?

Everything was the same except for the grounding method in test nil 2. In this case, the processing gas (0.+c2ctF6) was used, the pressure in the processing chamber 1 was 30 Pa, and the high frequency power density was 0.7 w/cd.

Comparing the experimental results, as shown in Figure 5,
Regarding the etching speed of Po1y-8i, the etching speed 17 of the grounding circuit 7 grounded through the fill 7a is higher than the etching speed 15 of the grounding circuit 6 directly grounded6. 5i02, the selection ratio of the grounding circuit 6 which is directly grounded is 16, and the selection ratio of the grounding circuit 7 which is grounded through the coil 7a is 18.
It is thicker than

The above results can be explained from the high frequency voltage at point A shown in FIG. 2 obtained through experiment. Diagram 2 shows the potential between the sample electrode 2 and the opposite electrode 3, where 10 is the sample electrode 2.
, 11 is the surface of the counter electrode 3, and the plasma potential between each electrode is 12. The potential on the surface of sample electrode 2 is O
However, in reality, because a high frequency is applied,
As shown in Figure 3 and Figure 4, a high frequency voltage with a certain amplitude is applied. Comparing this voltage between the two grounding systems, the waveform 14 of the grounding circuit 7 grounded via the coil 7a has a larger amplitude than the waveform 13 of the grounding circuit 6 directly grounded. There is.

There is a proportional relationship between the amplitude of the high-frequency voltage and the energy of the ions emitted from the sample 9).As the amplitude increases, the energy of the ions becomes thicker (becomes thicker), and the kneeing speed increases due to the increase in the sputtering effect.On the other hand, the amplitude When is small, the energy of the ion becomes small.

As the sputtering effect decreases, etching becomes mainly a radical reaction.

Etching progresses by a chemical reaction caused by radicals and a sputtering effect caused by ions, but in this case Po1
The etching of y-8i is mainly caused by a radical reaction, while the etching of the SiO layer of the base film is mainly caused by a sputtering effect.

Therefore, when the amplitude is small, the reduction in the etching rate of SiO2 is significant compared to Po1y-8i,
The selectivity with Po1y-8i increases.

As described above, according to this embodiment, considering the etching number of the sample using 5i02 as the base film and Po1y-8i as the gate material, the coil 7a that can increase the etching speed from the beginning of etching to just etching. When etching is performed using the ground circuit 7 that is grounded through the This has the advantage that the etching processing time is short and etching with small undercuts can be achieved.

In this embodiment, a coil is used as a means for loading impedance, but a resistor, a capacitor, or a combination thereof may also be used.

〔Effect of the invention〕

According to the present invention, with the anode cuff ring method, KN¥
By switching the impedance on the L pole side between a square tube grounded circuit and a non-grounded circuit, it is possible to increase the processing speed of the gate material and increase the selectivity with the underlying film. effective.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a dry etching device as an embodiment of the present invention, Fig. 9A2 shows the plasma potential between the electrodes in Fig. 1, and Fig. 3. The 54th factor is a diagram showing the voltage waveform at point A in FIG. 2, and FIG. 5 is a diagram showing the experimental results using the apparatus shown in FIG. 1...Processing chamber, 2...Sample electrode, 3...
Counter electrode, 4... Matching box, 5... High frequency power supply, 6... Directly grounded grounding circuit, 7.
...A grounding circuit that is grounded via the coil 7a, 8.
...Choice switch, 9;- /Tl Figure 5

Claims (1)

[Claims] 1. In a dry etching apparatus having a sample electrode for disposing a sample in a processing chamber supplied with a processing gas and evacuated to a predetermined pressure, and a counter electrode facing the sample electrode, A high-frequency power supply that applies a high-frequency voltage is connected to the sample electrode through a device, and means is provided for switching between a grounding circuit that is directly grounded to the sample electrode and a grounding circuit that is grounded through a means that loads an impedance. dry etching equipment.