JP2001118826A - Dry etching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry etching system which can accomplish plasma etching with smaller power consumption. SOLUTION: A gas introducing pipe 13 connected to an etching gas introducing port 12 made through the top of an etching chamber 10 is constituted in such a way that a prescribed portion of the pipe 13 near the chamber 10 is constituted of an insulating material, such as the ceramic pipe 131, and both end sections of the pipe 131 are coupled with the pipe 13 by means of O-rings 15. First and second electrods 18 and 19 are provided in such a way that the electrodes 18 and 19 cover the ceramic pipe 131. The electrodes 18 and 19 are constituted so that a high frequency may be impressed upon the electrodes 18 and 19 from a high-frequency power source V through the ceramic pipe 131. Before an etching gas is introduced to the chamber 10, a plasma of the gas is generated by means of a plasma generating mechanism PLSM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry etching apparatus for etching a semiconductor wafer by introducing an etching gas into an etching chamber.

[0002]

2. Description of the Related Art A dry etching apparatus is an apparatus for selectively etching a wafer by supplying a desired etching gas to a wafer in a semiconductor device manufacturing process. In recent years, a technique of converting an etching gas supplied to an etching chamber into plasma and using plasma etching has been generalized.

FIG. 5 is a schematic view showing the structure of a main part of a conventional dry etching apparatus. Etching chamber 50
Includes a mounting table 51 for the semiconductor wafer W and a gas supply head 52 therein. Mounting table 51 and gas supply head 52
Serve also as an upper electrode and a lower electrode for plasma induction by the high frequency power supply V, respectively. The gas supply head 52 is
It is connected to a gas introduction pipe 53 in which a mass flow control valve MFC or the like is provided. The exhaust pipe 54 mainly guides the reacted exhaust gas to the outside of the etching chamber 50.

A predetermined amount of each gas type flows from a gas unit (not shown) through the gas introduction pipe 53, and the gas E for etching is
G is supplied. The etching gas EG introduced into the etching chamber 50 is turned into plasma in the etching chamber 50. Plasma etching gas PEG
A plasma etching process is performed on the semiconductor wafer W.

[0005]

SUMMARY OF THE INVENTION Etching chamber 5
0 has a certain volume due to the need to mount a wafer. Accordingly, the high frequency power supply V needs a considerable power (500 to 1000 W) to convert the etching gas into plasma in the etching chamber 50. In addition, higher power is needed to increase the plasma conversion rate,
There is a problem that power consumption is large.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a dry etching apparatus which can achieve plasma etching with lower power consumption.

[0007]

According to the present invention, there is provided a dry etching apparatus in which a semiconductor wafer is placed inside a chamber and a desired etching is performed on the semiconductor wafer by an introduced etching gas. A mechanism is provided for converting an etching gas into a plasma in a region having a smaller volume than the chamber, and the etching gas is supplied to the chamber.

[0008] A dry etching apparatus as a more preferred embodiment of the present invention has a mounting table for a semiconductor wafer inside, a chamber into which an etching gas is introduced, a pipe for introducing the etching gas connected to the chamber, and A plasma generating mechanism for converting the etching gas into plasma provided at a predetermined location near the chamber with respect to the introduction pipe.

According to the present invention, the etching gas is turned into plasma in a region (volume for introducing the etching gas) smaller in volume than the chamber. As a result, the plasma of the etching gas is realized with lower power than that of the plasma in the chamber.

[0010]

FIG. 1 is a cross-sectional view showing a main configuration of a dry etching apparatus according to a first embodiment of the present invention. The etching chamber 10 has a semiconductor wafer W inside.
Mounting table 11 is provided. An etching gas inlet 12 is provided in the upper part of the chamber 10. The etching gas inlet 12 is connected to a gas inlet pipe 13 in which a mass flow control valve MFC and the like are provided. The discharge pipe 14 functions as a butterfly valve BV, a pump PMP, or the like, and mainly guides the reacted exhaust gas to the outside of the etching chamber 10.

The gas introduction pipe 13 is, for example, a stainless steel pipe S
US. However, in the gas introduction pipe 13, there is a portion where a predetermined portion near the etching chamber 10 is formed of an insulating material, for example, a ceramic tube 131. Both ends of the ceramic tube 131 are connected to the stainless steel tube SUS by, for example, O-rings 15. Further, in the gas introduction pipe 13, the valve 1 is placed before and after the ceramic pipe 131.
6, 17 are deployed.

Further, first and second electrodes 18 and 19 are provided so as to cover the ceramic tube 131. High frequency is applied to the first and second electrodes 18 and 19 through the ceramic tube 131 by the high frequency power supply V1. Such a plasma generating mechanism PLSM
Thereby, the etching gas is turned into plasma before being introduced into the chamber 10.

The control of the introduction of the etching gas in the dry etching apparatus will be described. First, the valve 17 is opened, and a high frequency is applied to the ceramic tube 131 by the plasma generating mechanism PLSM. Next, a predetermined amount of each gas type flows from a gas unit (not shown), and the gas EG for etching is supplied to the gas introduction pipe 13 by opening the mass flow control valve MFC and the valve 16.

When the etching gas EG passes through the ceramic tube 131, a high frequency is applied.
It is turned into plasma. That is, when the gas EG passes through the ceramic tube 131, the plasma etching gas PE
G is introduced into the etching chamber 10. Thus, the semiconductor wafer W is subjected to the plasma etching.

FIGS. 2 (a) and 2 (b) are external views showing the form of electrodes formed on a ceramic tube relating to the plasma forming mechanism of FIG. That is, the ceramic tube 1
The electrodes 18 and 19 that cover 31 have a configuration in which a cylinder is divided and opposed to each other, for example, as shown in FIG. Alternatively, as shown in FIG. 2B, the cylinder may be divided so that adjacent electrodes face each other in a comb shape. This has an advantage that the electric field power is increased since the facing area of the two electrodes 18 and 19 is increased as compared with the configuration of FIG.

According to the configuration of the first embodiment, the etching gas EG is converted into plasma in a small volume area (in the gas introduction pipe 13) before being introduced into the etching chamber 10 by the plasma conversion mechanism PLSM. Is done. That is, the plasma etching gas PEG is supplied to the etching chamber 10 in advance by passing through the inside of the ceramic tube 131. In this case, the plasma can be formed with a lower power (for example, 20 to 30 W) than when the etching gas is converted into plasma in the etching chamber. As a result, power consumption is significantly reduced.

Further, there is an advantage in terms of reducing PFC (global warming gas) emissions. This is because, unlike the dry etching apparatus of the related art, the plasma is generated with the supply of the etching gas. This will be described below.

In the conventional dry etching apparatus, at the start of operation, a raw gas for etching is flowed to some extent in the chamber and the pressure is controlled (gas stabilization time). When the pressure control is completed after the gas stabilization time has elapsed, a high frequency is applied in the chamber, and the etching gas is turned into plasma for the first time. That is, during the gas stabilization time (for example, 10 to 20 seconds), the raw gas for etching becomes PF
There is a concern that C will be discharged outside.

On the other hand, in the configuration of the present invention, the plasma etching gas PEG is supplied to the etching chamber 10 in advance by the plasma generating mechanism PLSM. Therefore, raw gas as PFC (raw gas in CO ₂ conversion value)
Is not emitted outside. Therefore, it helps to reduce PFC emissions and does not adversely affect the environment.

FIG. 3 is a cross-sectional view showing a main configuration of a dry etching apparatus according to a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. In this embodiment, different points from the first embodiment are as follows.
That is, a configuration for providing an electric field for drawing a plasma gas in the etching chamber 10 is added.

A mounting table 21 for a semiconductor wafer W is provided inside the etching chamber 10. This mounting table 2
1 becomes the lower electrode 211. An etching gas inlet 22 is provided in the upper part of the chamber 10. An upper electrode 221 is formed around the etching gas inlet 22.

The other points are the same as in the first embodiment. That is, the etching gas inlet 22 is connected to the gas inlet pipe 13 provided with a mass flow control valve MFC and the like. The discharge pipe 14 functions as a butterfly valve BV, a pump PMP, or the like, and mainly guides the reacted exhaust gas to the outside of the etching chamber 10. The plasma generating mechanism PLSM is the same as that of the first embodiment, and the configuration of the electrodes 18 and 19 as shown in FIGS. 2A and 2B can be considered.

The control of the introduction of the etching gas in the dry etching apparatus will be described. First, the valve 17 is opened, and a high frequency is applied to the ceramic tube 131 by the plasma generating mechanism PLSM. Next, a predetermined amount of each gas type flows from a gas unit (not shown) and the mass flow control valve M
When the FC and the valve 16 are opened, the etching gas EG is supplied to the gas introduction pipe 13.

The gas EG for etching is the ceramic tube 1
When passing through 31, high-frequency is applied and plasma is generated. The plasma etching gas PEG introduced into the etching chamber 10 induces plasma by an electric field generated by application of the high-frequency power supply V2 between the upper electrode 221 and the lower electrode 211 (the mounting table 21). , A process by plasma etching is performed.

According to the configuration of the second embodiment, the etching gas EG is converted into plasma in a small volume region before being introduced into the etching chamber 10.
As a result, the etching gas can be turned into plasma with a low power of, for example, about 20 to 30 W, and the power consumption is greatly reduced.

Further, the plasma etching gas PEG introduced into the chamber 10 is actively drawn into the mounting table 21 side of the semiconductor wafer W as a lower electrode, and the etching efficiency is improved. The power consumed for drawing the plasma may be as small as 2 to 3 W.
Since only about 0 to 15 W is required, it is understood that the power consumption is smaller than that of the related art.

In addition, as in the first embodiment, there is an advantage in reducing PFC gas (global warming gas) emissions. This is because, unlike the dry etching apparatus of the related art, the plasma is generated with the supply of the etching gas.

FIG. 4 is a cross-sectional view showing a main configuration of a dry etching apparatus according to a third embodiment of the present invention. The same parts as those in the second embodiment are denoted by the same reference numerals. In this embodiment, different points from the second embodiment are as follows.
The upper electrode in the etching chamber 10 has a shower head structure integrated with a gas inlet.

A mounting table 21 for a semiconductor wafer W is provided in the etching chamber 10. This mounting table 2
1 becomes the lower electrode 211. An upper electrode 231 having a plurality of etching gas inlets 23 is formed above the chamber 10 (shower head SH).

The rest is the same as the second embodiment. That is, the etching gas inlet 22 is connected to the gas inlet pipe 13 provided with a mass flow control valve MFC and the like. The discharge pipe 14 functions as a butterfly valve BV, a pump PMP, or the like, and mainly guides the reacted exhaust gas to the outside of the etching chamber 10. The plasma generating mechanism PLSM is the same as that of the first embodiment, and the configuration of the electrodes 18 and 19 as shown in FIGS. 2A and 2B can be considered.

The control of the introduction of the etching gas in the dry etching apparatus will be described. First, the valve 17 is opened, and a high frequency is applied to the ceramic tube 131 by the plasma generating mechanism PLSM. Next, a predetermined amount of each gas type flows from a gas unit (not shown) and the mass flow control valve M
When the FC and the valve 16 are opened, the etching gas EG is supplied to the gas introduction pipe 13.

The etching gas EG is the ceramic tube 1
When passing through 31, high-frequency is applied and plasma is generated. The plasma etching gas PEG is introduced from the plurality of inlets 23, and plasma is drawn between the upper electrode 231 and the lower electrode 211 (the mounting table 21) by an electric field generated by application of the high frequency power supply V2. With this configuration, the semiconductor wafer W is subjected to processing by plasma etching.

According to the configuration of the third embodiment, the etching gas EG is converted into plasma in a small volume region before being introduced into the etching chamber 10.
As a result, the etching gas can be turned into plasma with a low power of, for example, about 20 to 30 W, and the power consumption is greatly reduced.

The plasma etching gas PEG is
It is almost uniformly introduced into a wide area of the chamber 10 from the plurality of inlets 23 formed in the upper electrode 231, and is positively drawn into the mounting table 21 side of the semiconductor wafer W as the lower electrode. This contributes to an improvement in etching efficiency. The power consumed for drawing the plasma is 2 to
Since the power consumption can be as small as 3 W, and the power consumption is as large as about 10 to 15 W, it can be seen that the power consumption is smaller than that of the conventional technology.

In addition, as in the first embodiment, there is an advantage in reducing PFC gas (global warming gas) emissions. This is because, unlike the dry etching apparatus of the related art, the plasma is generated with the supply of the etching gas.

According to each of the above embodiments, the mechanism for converting the etching gas into plasma is provided in a region (gas introduction pipe) outside the chamber having a smaller volume than the etching chamber. As a result, the etching gas that has been converted into plasma in advance is supplied into the etching chamber. Such a plasma generating mechanism can achieve the plasma conversion of the etching gas with low power, and further contributes to the reduction of PFC emission.

[0037]

As described above, according to the present invention, since the etching gas is converted into plasma in a region having a smaller volume than the chamber (the piping for introducing the etching gas), the plasma can be formed with low power. Further, since an etching gas that has been converted into plasma can be introduced into the chamber, it contributes to reduction of PFC (global warming gas) emissions. As a result, a highly reliable dry etching apparatus which has low power and does not adversely affect the external environment can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main configuration of a dry etching apparatus according to a first embodiment of the present invention.

FIGS. 2 (a) and 2 (b) are external views each showing a form of an electrode formed on a ceramic tube relating to the plasma forming mechanism of FIG.

FIG. 3 is a cross-sectional view illustrating a main configuration of a dry etching apparatus according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a main configuration of a dry etching apparatus according to a third embodiment of the present invention.

FIG. 5 is a schematic view showing a configuration of a main part of a conventional dry etching apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Etching chamber 11,21 ... Placement table 12,22,23 ... Etching gas inlet 13 ... Gas inlet tube 131 ... Ceramic tube 14 ... Discharge tube 15 ... O-ring 16,17 ... Valve 18 ... First electrode 19 ... Second electrode 211: Lower electrode 221, 231: Upper electrode BV: Butterfly valve EG: Etching gas PMP: Pump PEG: Plasma etching gas PLSM: Plasma forming mechanism SUS: Stainless steel tube V1, V2: High frequency power supply W: Wafer

Claims (4)

[Claims] 1. A dry etching apparatus in which a semiconductor wafer is placed inside a chamber and a desired etching is performed on the semiconductor wafer by an introduced etching gas, wherein the etching is performed in a region having a smaller volume than the chamber outside the chamber. A mechanism for converting plasma for use into plasma, wherein an etching gas that is converted into plasma is supplied to the chamber. 2. A chamber having a mounting table for a semiconductor wafer therein, into which an etching gas is introduced, a pipe for introducing the etching gas connected to the chamber, and a predetermined location near the chamber with respect to the introduction pipe. A dry etching apparatus comprising: an etching gas plasma generating mechanism. 3. The plasma-generating mechanism is provided such that a predetermined portion of the introduction pipe is a pipe made of an insulating material, and first and second electrodes to which a high frequency is applied through the pipe cover the pipe. 3. The dry etching apparatus according to claim 2, wherein: 4. The dry etching apparatus according to claim 2, wherein a high frequency for drawing plasma is applied to the mounting table of the semiconductor wafer.