JP4286576B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus for applying plasma to a substrate to be processed, such as a semiconductor wafer or a glass substrate for a liquid crystal display device, to perform a predetermined plasma process such as an etching process or a film forming process.
[0002]
[Prior art]
Conventionally, in the field of manufacturing semiconductor devices, plasma is generated in a vacuum chamber, and this plasma is applied to a substrate to be processed, such as a semiconductor wafer or a glass substrate for a liquid crystal display device, thereby performing predetermined processing, for example, A plasma processing apparatus that performs an etching process, a film forming process, and the like is used.
[0003]
In such a plasma processing apparatus, for example, a so-called parallel plate type plasma processing apparatus, a mounting table for mounting a semiconductor wafer or the like is provided in the vacuum chamber, and the vacuum chamber is opposed to the mounting table. A shower head is provided on the ceiling, and a pair of parallel plate electrodes is constituted by the mounting table and the shower head.
[0004]
Then, a predetermined processing gas is introduced from the shower head into the vacuum chamber and evacuated from the bottom of the vacuum chamber, whereby a processing gas atmosphere having a predetermined degree of vacuum is created in the vacuum chamber. A processing gas plasma is generated by supplying high-frequency power of a predetermined frequency between the head and the semiconductor wafer, and the plasma is applied to the semiconductor wafer to perform processing such as etching of the semiconductor wafer.
[0005]
In the plasma processing apparatus as described above, in order to exhaust air uniformly from the periphery of the mounting table to form a uniform flow of processing gas around the semiconductor wafer and to prevent leakage of plasma from the processing space, Is provided with an exhaust ring formed in the shape of an annular plate and having a large number of through holes and slit-shaped exhaust passages (see, for example, Patent Document 1).
[0006]
As described above, the exhaust ring has a function of preventing plasma leakage from the processing space in the vacuum chamber. In order to improve the function of preventing such plasma leakage, It is necessary to reduce the opening area of the exhaust passage or to increase the length of the exhaust passage so that electrons do not easily pass through the exhaust passage. Note that when plasma leakage occurs, the plasma becomes unstable, and it becomes difficult to perform predetermined plasma processing on a semiconductor wafer or the like. For this reason, it is necessary to reduce the possibility that plasma leakage occurs as much as possible.
[0007]
However, if the function of preventing the plasma leakage of the exhaust ring is improved as described above, sufficient conductance for the gas cannot be obtained. For this reason, there is a problem that the process that can be executed is limited because the vacuum exhaust performance is lowered. On the other hand, in order to avoid such a problem, if a high evacuation capability is to be ensured, a large-sized and high-performance vacuum pump is required, which increases the manufacturing cost of the apparatus.
[0008]
[Patent Document 1]
Japanese Utility Model Laid-Open No. 5-8937 (FIG. 1-3).
[0009]
[Problems to be solved by the invention]
As described above, in the conventional plasma processing apparatus, when the function of preventing the plasma leakage of the exhaust ring is improved, the conductance with respect to the gas is lowered, and it is difficult to achieve both of them. For this reason, there has been a problem that a desired plasma treatment cannot be performed due to the occurrence of plasma leak, and a process that can be performed is restricted due to a decrease in conductance with respect to gas.
[0010]
The present invention has been made in response to such a conventional situation, has a high gas conductance capability, can cope with a wide range of processes without causing an increase in manufacturing cost, and prevents plasma leakage. An object of the present invention is to provide a plasma processing apparatus which has a high function and can perform good plasma processing with stable plasma.
[0011]
[Means for Solving the Problems]
That is, the plasma processing apparatus according to claim 1 is a vacuum chamber that accommodates a substrate to be processed, a mounting table that is disposed in the vacuum chamber and on which the substrate to be processed is mounted, and in the vacuum chamber, A plasma generation mechanism for generating plasma for performing a predetermined process on the substrate to be processed, an exhaust ring disposed around the mounting table and having an exhaust path formed therein, and the vacuum through the exhaust path a plasma processing apparatus comprising a vacuum evacuation mechanism for evacuating the chamber, the exhaust ring, and vertically into the formed side wall portion with respect to the mounting surface of the mounting table, the lower end of the side wall portions And a bottom portion extending inward from the inside, and the exhaust passage is formed at least in the side wall portion.
[0012]
The plasma processing apparatus according to claim 2 is the plasma processing apparatus according to claim 1, wherein the side wall portion of the exhaust ring has an inner cylindrical member and an outer cylindrical shape that are concentrically arranged at a predetermined interval. The opening provided in the said inner cylindrical member and the opening provided in the said outer cylindrical member are shifted and arrange | positioned, It is characterized by the above-mentioned.
[0013]
The plasma processing apparatus according to claim 3 is the plasma processing apparatus according to claim 2, wherein the opening provided in the inner cylindrical member and the opening provided in the outer cylindrical member are vertically long. It is formed in a rectangular shape and is provided in a plurality at predetermined intervals along the circumferential direction.
[0014]
The plasma processing apparatus according to claim 4 is the plasma processing apparatus according to claim 3, wherein the opening provided in the inner cylindrical member, and between the inner cylindrical member and the outer cylindrical member. The exhaust passage is formed from the formed gap and the opening provided in the outer cylindrical member.
[0015]
A plasma processing apparatus according to a fifth aspect is the plasma processing apparatus according to any one of the first to fourth aspects, wherein the exhaust path is provided at the bottom of the exhaust ring.
[0016]
The plasma processing apparatus according to claim 6, wherein a vacuum chamber that accommodates a substrate to be processed, a mounting table that is disposed in the vacuum chamber and on which the substrate to be processed is mounted, and the processing target in the vacuum chamber A plasma generating mechanism for generating plasma for performing a predetermined treatment on the substrate; an exhaust ring disposed so as to surround the periphery of the mounting table; and an exhaust path formed therein; and the exhaust path from below the exhaust ring A vacuum exhaust mechanism for evacuating the vacuum chamber through the exhaust ring, wherein the exhaust ring includes a side wall portion formed perpendicular to the mounting surface of the mounting table, and A bottom portion extending inward from a lower end of the side wall portion, and the side wall portion is disposed with an inner cylindrical member having a first opening and a gap between the inner cylindrical member and the first cylindrical member. What is the opening of Comprising an outer cylindrical member having a second opening to position said first enters through the opening into the gap, the exhaust passage to be derived from the second opening through the said gap Is formed, and the plasma is trapped in the gap.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to the drawings.
[0018]
FIG. 1 schematically shows a configuration of an embodiment in which the present invention is applied to a parallel plate type plasma etching apparatus for etching a semiconductor wafer. In FIG. For example, a cylindrical vacuum chamber made of aluminum or the like and configured to be airtightly closed is shown.
[0019]
A mounting table 2 for mounting the semiconductor wafer W is provided in the vacuum chamber 1, and the mounting table 2 also serves as a lower electrode. Further, a shower head 3 constituting an upper electrode is provided on the ceiling portion in the vacuum chamber 1, and a pair of parallel plate electrodes is constituted by the mounting table 2 and the shower head 3. Yes.
[0020]
The shower head 3 is provided with a gap 4 for gas diffusion and a plurality of pores 5 so as to be positioned below the gap 4 for gas diffusion. A predetermined processing gas supplied from the processing gas supply system 6 is diffused in the gas diffusion gap 4 and supplied from the pores 5 toward the semiconductor wafer W in a shower shape. In the present embodiment, the shower head 3 is at a ground potential, but a high frequency power source may be connected to the shower head 3 so that high frequency power is applied to both the mounting table 2 and the shower head 3.
[0021]
On the other hand, two high-frequency power supplies 9 and 10 are connected to the mounting table 2 via two matching units 7 and 8, and the mounting table 2 has two predetermined frequencies (for example, 100 MHz and 3.2 MHz). The high frequency power can be superimposed and supplied. In addition, it is good also as a structure which supplies only the high frequency electric power of 1 type of frequency by making only one high frequency power supply which supplies high frequency power to the mounting base 2. FIG.
[0022]
An electrostatic chuck 11 for attracting and holding the semiconductor wafer W is provided on the mounting surface of the semiconductor wafer W of the mounting table 2. The electrostatic chuck 11 has a configuration in which an electrostatic chuck electrode 11b is disposed in an insulating layer 11a, and a DC power source 12 is connected to the electrostatic chuck electrode 11b. Further, a focus ring 13 is provided on the upper surface of the mounting table 2 so as to surround the periphery of the semiconductor wafer W.
[0023]
An exhaust port 14 is provided at the bottom of the vacuum chamber 1, and an exhaust system 15 including a vacuum pump is connected to the exhaust port 14.
[0024]
In addition, an exhaust ring 16 formed in an annular shape is provided around the mounting table 2. As shown in FIG. 2, the exhaust ring 16 includes a side wall portion 17 formed substantially vertically downward, and a bottom portion 18 extending vertically from the lower end of the side wall portion 17 toward the inside. It has.
[0025]
As shown in FIG. 3, the side wall portion 17 includes an inner cylindrical member 19 and an outer cylindrical member 20 that are concentrically arranged with a predetermined interval. The inner cylindrical member 19 is provided with a plurality of vertically long rectangular openings 19a that constitute an exhaust passage at predetermined intervals along the circumferential direction. As shown in FIGS. 3 and 4, the outer cylindrical member 20 is also provided with a plurality of vertically long rectangular openings 20a that similarly form an exhaust passage, and the openings 19a and 20a are circular. They are shifted in the circumferential direction by a predetermined interval (distance C shown in FIG. 4).
[0026]
Then, as shown by an arrow in FIG. 4, it passes through the opening 19 a of the inner cylindrical member 19, and then passes through the gap 21 formed between the inner cylindrical member 19 and the outer cylindrical member 20. Thereafter, an exhaust path is formed so that the gas is exhausted through the opening 20a of the outer cylindrical member 20.
[0027]
The dimensions A to D shown in FIG. 4, that is, the width A of the gap 21, the width B of the opening 19 a, the deviation width C between the opening 19 a and the opening 20 a, and the thickness D of the inner cylindrical member 19 are as follows:
C / A> 1
B> 2A
B / D> 1
It is configured to satisfy.
[0028]
In other words, the exhaust ring 16 has a structure in which plasma is trapped in the gap 21. Therefore, the width A of the gap 21 is set to be relatively narrow, and the deviation width C between the opening 19a and the opening 20a is plasma. Is set to have a sufficient distance to trap.
[0029]
In addition, the width B of the opening 19a is not a structure for trapping plasma here, so that the opening 19a has a wide opening so that a sufficient opening area can be secured and sufficient conductance can be secured. The thickness D of the shaped member 19 is set to be thin. It should be noted that the thickness of the outer cylindrical member 20 and the opening 20a are set similarly.
[0030]
FIG. 4 schematically shows the configuration of the exhaust ring 16 and does not show actual dimensions. Regarding the actual dimensions, for example, when the width A of the gap 21 is 1 mm, the width B of the opening 19a is larger than 2 mm, for example, about several millimeters. Further, the deviation width C between the opening 19a and the opening 20a and the thickness D of the inner cylindrical member 19 are also set in consideration of the ease of processing, etc., with a size that is calculated backward from the above conditions. The
[0031]
Further, the length of the side wall portion 17 in the vertical direction is also set to a length that can sufficiently secure the opening area of the opening 19a and the opening 20a and ensure sufficient conductance.
[0032]
As described above, by forming an exhaust passage in the side wall portion 17 of the exhaust ring 16, by making the side wall portion 17 longer in the vertical direction, a sufficient opening area can be secured and sufficient conductance can be ensured. it can. Further, even if the opening area is increased in this way, the diameter of the exhaust ring 16 is constant, so that the diameter of the vacuum chamber 1 does not need to be increased, and the footprint of the apparatus does not increase.
[0033]
In addition, as described above, the exhaust passage of the side wall portion 17 is constituted by the opening 19a, the gap 21, and the opening 20a, so that the function of preventing plasma leakage is sufficiently secured and the opening area is sufficiently large. Therefore, sufficient conductance can be ensured.
[0034]
That is, by increasing the opening area of the opening 19a, the electrons in the plasma pass through the opening 19a together with the gas flow as shown by the arrows in FIG. Since there is the member 20, the possibility that electrons pass through the gap 21 and is led out from the opening 20a is extremely low, and the possibility that the plasma leaks out of the opening 20a is extremely low. Even if the opening area is increased so as to ensure conductance, the function of preventing plasma leakage can be sufficiently ensured.
[0035]
Further, in the present embodiment, the bottom portion 18 of the exhaust ring 16 is also formed with a large number of circular holes 18a, and an exhaust path is formed by these openings 18a. In this manner, the conductance can be further increased by forming an exhaust passage in the bottom portion 18 as well.
[0036]
The exhaust path of the bottom portion 18 of the exhaust ring 16 as described above may be an exhaust path having the above-described configuration provided in the side wall portion 17 instead of an opening such as a circular hole. However, since the bottom portion 18 is far away from the region where the plasma is formed, the function of preventing plasma leakage does not need to be considered so much, and can therefore be an opening made of a circular hole or the like. Further, when sufficient conductance can be ensured by the exhaust passage provided in the side wall portion 17, the exhaust passage of the bottom portion 18 may not be provided.
[0037]
The exhaust ring 16 may be made of any material as long as it is conductive. For example, stainless steel or aluminum having an alumite film or sprayed film formed on the surface can be used. Thus, the exhaust ring 16 made of a conductive material is electrically connected to the ground potential.
[0038]
The interior of the vacuum chamber 1 can be set to a predetermined vacuum atmosphere by evacuating from the exhaust port 14 by the exhaust system 15 through the exhaust ring 16 configured as described above.
[0039]
Further, a magnetic field forming mechanism 22 is provided around the vacuum chamber 1 so that a desired magnetic field can be formed in the processing space in the vacuum chamber 1. The magnetic field forming mechanism 22 is provided with a rotating mechanism 23, and is configured to rotate the magnetic field in the vacuum chamber 1 by rotating the magnetic field forming mechanism 22 around the vacuum chamber 1.
[0040]
Next, an etching process in the plasma etching apparatus configured as described above will be described.
[0041]
First, a gate valve (not shown) provided at a loading / unloading port (not shown) is opened, and a semiconductor wafer W is loaded into the vacuum chamber 1 by a transfer mechanism or the like and placed on the mounting table 2. Thereafter, the semiconductor wafer W mounted on the mounting table 2 is attracted and held by applying a predetermined DC voltage from the DC power source 12 to the electrostatic chuck electrode 11 b of the electrostatic chuck 11.
[0042]
Next, after the transfer mechanism is retracted outside the vacuum chamber 1, the gate valve is closed, and the vacuum chamber 1 is evacuated by a vacuum pump or the like of the vacuum system 15, and the vacuum chamber 1 reaches a predetermined degree of vacuum. Then, a predetermined etching process gas is introduced into the vacuum chamber 1 from the process gas supply system 6 through the gas diffusion gap 4 and the pores 5 at a flow rate of, for example, 100 to 1000 sccm. The inside is maintained at a predetermined pressure, for example, about 1.33 to 133 Pa (10 to 1000 mTorr).
[0043]
In this state, high frequency power of a predetermined frequency (for example, 100 MHz and 3.2 MHz) is supplied from the high frequency power supplies 9 and 10 to the mounting table 2.
[0044]
As described above, a high frequency electric field is formed in the processing space between the shower head 3 and the mounting table 2 by applying high frequency power to the mounting table 2. Further, a predetermined magnetic field is formed in the processing space by the magnetic field forming mechanism 22. As a result, a predetermined plasma is generated from the processing gas supplied to the processing space, and a predetermined film on the semiconductor wafer W is etched by the plasma.
[0045]
At this time, as described above, since the conductance of the exhaust ring 16 is high, it is possible to efficiently perform evacuation from the inside of the vacuum chamber, and it is possible to easily achieve a high degree of vacuum without using a large and high performance vacuum pump. Can be set to In addition, since it is possible to reliably prevent plasma leakage in the exhaust ring 16, a desired etching process can be performed with high accuracy by stable plasma.
[0046]
Then, when a predetermined etching process is executed, the supply of high-frequency power from the high-frequency power supplies 9 and 10 is stopped, the etching process is stopped, and the semiconductor wafer W is removed from the vacuum chamber by a procedure opposite to the above-described procedure. 1 Take out.
[0047]
Although the case where the present invention is applied to a plasma etching apparatus for etching a semiconductor wafer has been described in the above embodiment, the present invention is not limited to such a case. For example, a substrate other than a semiconductor wafer may be processed, and processing other than etching, for example, a film forming processing apparatus such as CVD can be applied.
[0048]
【The invention's effect】
As described above, according to the plasma processing apparatus of the present invention, it has a high gas conductance capability, can cope with a wide range of processes without causing an increase in manufacturing cost, and has a function of preventing plasma leakage. Good plasma treatment can be performed with high and stable plasma.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall schematic configuration of a plasma processing apparatus according to an embodiment of the present invention.
2 is a diagram showing a schematic configuration of a main part of the plasma processing apparatus of FIG. 1;
3 is a diagram showing a schematic configuration of a main part of the plasma processing apparatus of FIG. 1;
4 is a diagram showing a schematic configuration of a main part of the plasma processing apparatus of FIG. 1;
[Explanation of symbols]
W ... semiconductor wafer, 1 ... vacuum chamber, 2 ... mounting table, 3 ... shower head, 9, 10 ... high frequency power supply, 14 ... exhaust port, 15 ... exhaust system, 16 ... exhaust ring, 17 ... side wall, 18 ... bottom, 18a ... opening, 19 ... inner cylindrical member, 19a ... opening, 20 ... outer cylindrical member, 20a ... opening, 21 ... gap.

Claims (6)

A vacuum chamber for accommodating a substrate to be processed;
A mounting table disposed in the vacuum chamber and on which the substrate to be processed is mounted;
A plasma generating mechanism for generating plasma for performing a predetermined process on the substrate to be processed in the vacuum chamber;
An exhaust ring arranged around the mounting table and having an exhaust path formed therein;
A plasma processing apparatus comprising a vacuum exhaust mechanism for evacuating the vacuum chamber through the exhaust path,
The exhaust ring comprises a by relative mounting surface of the mounting table vertically into the formed side wall portion, a bottom portion extending inward from the lower end of the side wall portion, at least on the side wall portion, A plasma processing apparatus, wherein the exhaust path is formed. The plasma processing apparatus according to claim 1,
The side wall portion of the exhaust ring is composed of an inner cylindrical member and an outer cylindrical member that are concentrically arranged at a predetermined interval, an opening provided in the inner cylindrical member, and the outer cylindrical member A plasma processing apparatus, wherein an opening provided in a member is shifted from the opening. The plasma processing apparatus according to claim 2,
The opening provided in the inner cylindrical member and the opening provided in the outer cylindrical member are formed in a vertically long rectangular shape, and a plurality of openings are provided at predetermined intervals along the circumferential direction. A plasma processing apparatus. The plasma processing apparatus according to claim 3,
The exhaust provided from the opening provided in the inner cylindrical member, a gap formed between the inner cylindrical member and the outer cylindrical member, and the opening provided in the outer cylindrical member. A plasma processing apparatus, wherein a path is formed. A plasma processing apparatus according to any one of claims 1 to 4,
Furthermore, the said exhaust path is provided in the said bottom part of the said exhaust ring, The plasma processing apparatus characterized by the above-mentioned. A vacuum chamber for accommodating a substrate to be processed;
A mounting table disposed in the vacuum chamber and on which the substrate to be processed is mounted;
A plasma generating mechanism for generating plasma for performing a predetermined process on the substrate to be processed in the vacuum chamber;
An exhaust ring that is disposed so as to surround the mounting table and has an exhaust path, and a vacuum exhaust mechanism that evacuates the vacuum chamber from below the exhaust ring through the exhaust path. A plasma processing apparatus,
The exhaust ring has a side wall portion formed perpendicular to the mounting surface of the mounting table, and a bottom portion extending inward from the lower end of the side wall portion,
The side wall portion is
An inner cylindrical member having a first opening;
An outer cylindrical member having a second opening at a position away from the first opening and disposed with a gap from the inner cylindrical member;
The exhaust passage is formed so as to enter the gap from the first opening, pass through the gap and be led out from the second opening, and the plasma is trapped in the gap. A plasma processing apparatus.

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