JP3662101B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus that performs processing such as etching, ashing, and CVD using plasma.
[0002]
[Prior art]
Plasma processing apparatuses are widely used in the manufacture of devices such as LSI and LCD, and perform processing such as etching, ashing, and CVD by converting reactive gas into plasma. Among them, the dry etching technique using plasma has become an essential basic technique in the manufacture of devices such as LSI and LCD.
[0003]
In recent years, silicon wafers used for LSIs and glass substrates used for LCDs tend to become larger, and accordingly, it is further required to generate uniform plasma over a large area. In dry etching technology and embedding technology in thin film formation, it is important to independently control the generation of plasma and the energy of ions in the plasma.
[0004]
In view of this, the present applicant has proposed a plasma processing apparatus capable of generating uniform plasma over a large area and controlling the energy of ions (Japanese Patent Laid-Open No. 5-144773). In this apparatus, the ceiling portion of the reaction vessel is hermetically sealed with a microwave-permeable dielectric plate (hereinafter referred to as a microwave introduction plate), and a dielectric material through which microwaves propagate above the microwave introduction plate. A body layer is provided, and a high frequency is applied to the sample stage.
[0005]
In the apparatus configured as described above, since the microwave is propagated in a planar manner to the dielectric layer, even when the area of the dielectric layer and the microwave introduction plate is increased, a uniform plasma is obtained over a wide area in the reaction vessel. Can be easily generated. Further, by applying a high frequency to the sample stage in the reaction vessel, an electric circuit is formed between the sample stage and the grounding member (such as a side wall) via plasma, and a bias voltage can be generated on the sample surface. Therefore, the energy of ions in the plasma generated by the microwave can be controlled by this bias voltage. As described above, the generation of plasma and the energy of ions in the plasma can be controlled independently.
[0006]
However, when this apparatus is used, depending on the plasma processing conditions, the bias voltage generated on the surface of the sample placed on the sample stage may become unstable, and ion energy control may be difficult. For example, there are cases where etching cannot be performed with good reproducibility during etching of an oxide film (SiO ₂ film) or a thin film is formed on the contrary without the progress of etching.
[0007]
As a countermeasure against this, the present applicant has proposed a device capable of controlling ion energy more stably in Japanese Patent Laid-Open No. 6-104098. FIG. 4 is a schematic longitudinal sectional view showing the plasma processing apparatus. In this apparatus, a counter electrode 21 electrically grounded is provided on the reaction chamber 2 side of the microwave introduction plate 14 so as to face the sample stage 15. The counter electrode 21 is made of a metal plate such as aluminum (Al) and has a microwave supply hole 21a for introducing a microwave into the reaction chamber 2.
[0008]
FIG. 5 is an enlarged view of a portion B which is a side wall portion of the reaction vessel 11 of the apparatus. The counter electrode 21 is electrically grounded through the side wall portion of the reaction vessel 11. In addition, heaters 31 and 27 are provided in the upper part and the inner surface of the side wall of the reaction vessel 11, and the counter electrode 21 and the side wall are heated to a predetermined temperature.
[0009]
In this apparatus, since the counter electrode 21 is provided, the plasma potential when a high frequency is applied to the sample stage 15 is stabilized, and a stable bias voltage can be generated on the surface of the sample S. As a result, it is possible to control the energy of ions in the plasma, and the surface of the sample S can be irradiated with ions having appropriate energy.
[0010]
Further, in various plasma treatments, it is a very important technique to control the side wall of the reaction vessel 11 to be maintained at a predetermined temperature. For example, in the above-described etching of the SiO ₂ film, a fluorocarbon (C _x F _y ) gas is used as a process gas, but the gas is generated by decomposition of the process gas in the plasma so that etching of the resist (mask) is suppressed. It is necessary to collect the film formation species on the resist (mask) surface of the sample S. Therefore, the sample stage 15 is cooled to cool the sample S. On the other hand, the side wall of the reaction vessel 11 is controlled to be heated to about 150 to 200 ° C. in order to suppress the adhesion and deposition of reaction products that cause particles.
[0011]
[Problems to be solved by the invention]
In controlling the temperature of the side wall, in order to suppress the deposition of the reaction product on the inner surface of the side wall of the reaction vessel 11 facing the reaction chamber 2, particularly on the portion near the microwave introduction plate 14, this portion may be maintained at a high temperature. is important. However, in the apparatus shown in FIGS. 4 and 5, heat from the heaters 27 and 31 provided in the reaction vessel 11 diffuses to the entire side wall of the reaction vessel 11 and is radiated from the outer surface of the side wall, so that the thermal efficiency is very poor. Have the following problems. That is, heat may be released from the outer surface of the side wall and heating may be insufficient. To maintain the inner surface of the side wall at a predetermined temperature, it is necessary to raise the entire reaction vessel 11 to the predetermined temperature, and energy consumption If the outer surface of the side wall becomes hot, it is likely to cause trouble in terms of maintenance of peripheral devices.
Furthermore, the large contact area between the reaction vessel 11 and other members such as the chamber base, and the large heat capacity of the reaction vessel 11 and the upper electrode (counter electrode 21) also increase power consumption and make heat control difficult. ing.
[0012]
The present invention has been made in view of such circumstances. By adopting a configuration in which the heater is thermally suspended from the reaction vessel and attached, the temperature control of the reaction chamber side wall can be efficiently and easily performed with low power consumption. It is an object of the present invention to provide a plasma processing apparatus that can perform this.
[0013]
[Means for Solving the Problems]
The present invention relates to a plasma apparatus that generates plasma in a reaction vessel and processes a sample with the generated plasma, and the reaction vessel includes a reaction chamber in which the sample is placed and a periphery located around the reaction chamber. A partition member provided inside the reaction vessel to divide the chamber, a heater attached to the partition member, and a gas in the reaction chamber were exposed to the reaction chamber to evacuate the gas. An exhaust port opened in a side wall portion, and a hole provided in the vicinity of the exhaust port of the partition member so as to communicate the reaction chamber and the surrounding chamber are provided.
In addition, the present invention is characterized in that an introduction port is provided which is opened in a side wall portion exposed to the reaction chamber of the reaction vessel in order to introduce a reaction gas into the reaction chamber.
Furthermore, the present invention is characterized in that the partition member has a shape in which the lower part of the side wall of the reaction vessel is exposed to the reaction chamber as the side wall portion .
Furthermore, the present invention is characterized in that the plasma is generated by microwaves introduced into the reaction vessel.
Moreover, the present invention is characterized in that the partition member is detachably attached to the reaction vessel.
[0014]
Since the heat capacity of the side wall facing the reaction chamber can be reduced, the temperature can be controlled efficiently and easily, and the energy consumption is reduced. In order to easily control the temperature, it is desirable to make the surrounding chamber a vacuum.
[0015]
The present invention is characterized in that the partition member and the reaction vessel have conductivity and are electrically connected to each other.
Further, according to the present invention, the partition member includes a cylindrical side wall portion, an extending portion extending from the one end of the side wall portion to the reaction chamber side by a predetermined length, and the reaction from the other end of the side wall portion. It has the connection part which extends to the side wall of a container and connects the said side wall part and the said reaction container, It is characterized by the above-mentioned.
[0016]
By grounding the extended portion during plasma processing, the extended portion functions as an upper electrode when processing is performed by applying a high frequency to the sample stage, so that there is no need to separately provide an upper electrode. In general, the upper electrode needs to be maintained at a predetermined temperature like the side wall of the reaction chamber. However, since the upper electrode is connected to the partition member, the temperature of the upper electrode is controlled by a heater simultaneously with the partition member.
[0017]
In the present invention, a part of the reaction vessel is sealed with a sealing member, and a part of the partition member is in contact with the sealing member.
[0018]
Since a part (upper part) of the partition member is in contact with the sealing member, the plasma generated in the reaction chamber and the gas supplied to the reaction chamber can be prevented from flowing into the surrounding chamber. Therefore, the surrounding chamber can be kept clean and damage to the surrounding chamber due to plasma can be prevented.
[0019]
The present invention, before Symbol partition member Yes form hollow, characterized in that it comprises a means for supplying a cooling medium to the hollow portion.
[0020]
In the case of overheating due to the continuous plasma treatment, the partition member can be maintained at a predetermined temperature by supplying the refrigerant into the partition member and absorbing the heat .
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
FIG. 1 is a schematic longitudinal sectional view showing a plasma processing apparatus according to the present invention. In the figure, 11 is a circular reaction vessel made of a metal such as aluminum or stainless steel, and the ceiling is hermetically sealed by a microwave introduction plate 14 (sealing member). The microwave introduction plate 14 is formed of a dielectric material such as quartz glass (SiO ₂ ) or alumina (Al ₂ O ₃ ) that has excellent heat resistance and microwave transmission and has a small dielectric loss. In the lower part of the side wall of the reaction vessel 11, a reaction gas introduction port 19 and an exhaust port 20 are opened.
[0022]
A surface wave electric field leakage chamber 35 covered with a metal plate 37 except for one side surface is provided on the upper side of the reaction vessel 11, and this one side surface is connected to a microwave oscillator 39 that oscillates a microwave of 2.45 GHz, for example. The connected microwave waveguides 38 are connected. On the inner side of the upper wall of the surface wave electric field leakage chamber 35, a dielectric line 36 made of a material having a small dielectric loss, such as fluororesin, polyethylene, polystyrene, or the like, is disposed in the middle of the microwave waveguide 38.
[0023]
The reaction vessel 11 is partitioned into a reaction chamber 12 and a surrounding chamber 42 by a partition 41 made of a conductive material such as aluminum, an aluminum alloy, or stainless steel having a thickness of 10 to 100 mm. The partition 41 includes a cylindrical side wall portion 41a, an upper electrode portion (extension portion) 41b extending substantially horizontally from the upper end of the side wall portion 41a to the reaction chamber 12 side, and a lower end of the side wall portion 41a. It extends to the side wall of the reaction vessel 11 and has a connection part 41c for connecting them. A heater 43 is attached to the surface of the side wall 41a on the side of the surrounding chamber 42. The partition 41 is attached so that the upper surface of the upper electrode portion 41b is in contact with the microwave introduction plate. An exhaust port 44 for evacuating the surrounding chamber 42 is provided on the side wall of the reaction vessel 11.
[0024]
A sample stage 15 is disposed in the reaction chamber 12 so as to face the microwave introduction plate 14, and the sample S is placed thereon. The sample stage 15 includes an adsorption mechanism such as an electrostatic chuck for fixing and holding the sample S, and a constant temperature holding mechanism (for example, a mechanism for circulating a refrigerant) for holding the sample S at a constant temperature. Further, a high frequency power source 40 is connected to the sample stage 15, and a high frequency such as 400 kHz, 2 MHz, or 13.56 MHz is applied thereto.
[0025]
A method for performing plasma processing on the sample S in the plasma processing apparatus configured as described above will be described.
(1) The sample stage 15 on which the sample S is placed is maintained at a predetermined temperature in advance, the gas remaining in the peripheral chamber 42 is exhausted from the exhaust port 44, and the partition 41 and the peripheral chamber 42 are set to a predetermined temperature by the heater 43. Keep it heated.
(2) After exhausting the gas remaining in the reaction chamber 12 from the exhaust port 20, the process gas is introduced into the reaction chamber 12 from the introduction port 19.
[0026]
(3) A microwave is oscillated by the microwave oscillator 39 and the microwave is introduced into the dielectric layer 36 through the waveguide 38. A surface wave electric field leaks from the dielectric layer 36 to the surface wave electric field leakage chamber 35, and the electric field passes through the microwave introduction plate 14 to generate plasma in the reaction chamber 12.
(4) Almost simultaneously with the generation of the plasma, a high frequency is applied to the sample stage 15 by the high frequency power source 40 to generate a bias voltage on the surface of the sample S. The surface of the sample S is irradiated with ions while the energy of ions in the plasma is controlled by this bias voltage, and the sample S is subjected to plasma treatment.
[0027]
In the apparatus of the present invention, the heat capacity of the partition 41 which is the side wall of the reaction chamber 12 and the upper electrode part 41b corresponding to the conventional upper electrode 21 is much smaller than that of the corresponding part in the conventional apparatus. Therefore, the energy consumption is greatly reduced, and the time required for temperature rise is also shortened. In addition, since the surrounding chamber 42 is vacuum and the contact area between the partition 41 and other members is small, heat conduction is suppressed and heat retention is excellent, thereby enabling easy heat control.
[0028]
The main heat path from the heater 43 to the side wall of the reaction vessel 11 is a contact portion with a small area with the partition 41 and a portion facing the vacuum surrounding chamber 42, so that the side wall of the reaction vessel 11 is as hot as before. Never become. Accordingly, the temperature of the outer surface of the reaction vessel 11 does not become as high as that in the prior art, which is preferable from the viewpoint of maintenance of peripheral devices.
In addition, since the reaction chamber 12 and the surrounding chamber 42 are partitioned by the partition 41 and the microwave introduction plate 14 and are not communicated with each other, the plasma and process gas generated in the reaction chamber 12 flow into the surrounding chamber 42. do not do. Further, abnormal discharge of plasma in the surrounding chamber 42 does not occur. Therefore, it is possible to completely prevent the reaction product from adhering to the surrounding chamber 42, deposition, and damage to the surrounding chamber 42 due to plasma.
[0029]
It should be noted that a hole (exhaust hole) may be provided in the vicinity of the exhaust port 20 of the connecting portion 41c of the partition 41 so that the reaction chamber 12 and the surrounding chamber 42 communicate with each other. In this case, when the reaction chamber 12 is evacuated, the surrounding chamber 42 can be evacuated simultaneously, the apparatus structure is simplified, and the manufacturing cost can be reduced.
Further, since the communication part between the reaction chamber 12 and the surrounding chamber 42 is only in the vicinity of the exhaust port 20, the plasma and process gas generated in the reaction chamber 12 hardly flow into the surrounding chamber 42. Accordingly, it is possible to prevent adhesion and deposition of reaction products in the surrounding chamber 42, damage to the surrounding chamber 42 due to plasma, and occurrence of abnormal discharge in the surrounding chamber 42.
[0030]
The side wall (side wall part 41a) facing the reaction chamber 12 and the upper electrode part 41b are easily damaged by plasma. In this case, in the conventional apparatus, a treatment such as repairing the side wall of the reaction vessel 11 is required, whereas in the apparatus of the present invention, the inside of the surrounding chamber 42 is not damaged at all or is hardly damaged due to the above-described reason. Since there is only the partition 41, it is only necessary to replace this partition 41.
[0031]
The upper electrode portion 41b of the partition 41 shown in FIG. 1 is not always necessary. If the upper electrode portion 41b is not provided, the side wall portion 41a functions as a ground electrode. When the upper electrode portion 41b is not provided, the partition 41 is attached so that the upper end portion of the side wall portion 41a is in contact with the microwave introduction plate. The configuration without the upper electrode portion 41b can be applied to other plasma processing apparatuses that do not apply a high frequency to the sample stage 15.
[0032]
Embodiment 2. FIG.
FIG. 2 is a schematic longitudinal sectional view showing the plasma processing apparatus according to the second embodiment, and FIG. 3 is an exploded perspective view showing the main part of the partition. The cylindrical side wall portion 51a of the partition has a structure in which two curved plates 511 and 512 are bonded to each other. The convex portion 513 is formed. The partition 51 includes an upper electrode part 51b at the upper end of the side wall part 51a, and a connection part 51c at the lower end of the side wall part 51a.
[0033]
A side wall 51a is formed by bonding a curved plate 512 having no convex portion to a surface of the curved plate 511 having the vertically long convex portion 513. A refrigerant supply pipe 52 and a refrigerant discharge pipe 53 are communicated with the flow path in the side wall 51a. The refrigerant supply pipe 52 is installed outside the apparatus and is connected to a refrigerant tank 54 having a flow rate adjusting function. A predetermined flow rate of refrigerant is supplied.
Other configurations are the same as those of the first embodiment, and the same reference numerals are given and the description thereof is omitted.
[0034]
In the apparatus shown in the second embodiment, at the start of processing, the temperature of the side wall of the reaction chamber 12 is raised to a predetermined temperature in a short time by heating the partition 51 with the heater 43 as in the first embodiment. When the apparatus is overheated by the continuous plasma treatment, a refrigerant (for example, N ₂ gas) is supplied to the flow path in the side wall 51a to absorb heat, and the side wall temperature of the reaction chamber 12 is maintained at a predetermined temperature. As a result, the processing conditions in the first half and the second half of the processing are made uniform, and good reproducibility is obtained.
[0035]
【The invention's effect】
As described above, the plasma processing apparatus according to the present invention has a configuration in which the heater for controlling the side wall temperature of the reaction chamber is mounted so as to be thermally floated from the reaction vessel, thereby reducing the heat capacity of the side wall facing the reaction chamber. The present invention has an excellent effect such that the temperature control of the reaction chamber side wall can be performed efficiently and easily with low power consumption.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a plasma processing apparatus according to a first embodiment.
FIG. 2 is a schematic longitudinal sectional view showing a plasma processing apparatus according to a second embodiment.
FIG. 3 is an exploded perspective view showing a main part of the partition shown in FIG. 2;
FIG. 4 is a schematic longitudinal sectional view showing a conventional plasma processing apparatus.
5 is an enlarged cross-sectional view of a side wall of the plasma processing apparatus shown in FIG.
[Explanation of symbols]
12 reaction chamber
41, 51 divider
41a, 51a Side wall
41b, 51b Upper electrode section
42 Surrounding room
43 Heater
52 Refrigerant supply pipe
53 Refrigerant discharge pipe
54 Refrigerant tank S Sample

Claims (9)

In a plasma apparatus that generates plasma in a reaction vessel and processes a sample with the generated plasma,
The pre-Symbol reaction vessel, in order to split into a peripheral chamber located around the reaction chamber and the reaction chamber in which the sample is placed, a partition member provided on the inside of the reaction vessel,
A heater attached to the partition member ;
An exhaust port opened in a side wall portion exposed to the reaction chamber of the reaction vessel to exhaust the gas in the reaction chamber;
A plasma processing apparatus , comprising: a hole provided in a vicinity of the exhaust port of the partition member to communicate the reaction chamber and the surrounding chamber . The plasma processing apparatus according to claim 1, further comprising an introduction port that is open to a side wall portion exposed to the reaction chamber of the reaction vessel in order to introduce a reaction gas into the reaction chamber . The plasma processing apparatus according to claim 2, wherein the partition member has a shape in which a lower portion of a side wall of the reaction vessel is exposed to the reaction chamber as the side wall portion . The plasma processing apparatus according to claim 1 , wherein the plasma is generated by a microwave introduced into the reaction vessel . The plasma processing apparatus according to claim 1 , wherein the partition member is detachably attached to the reaction vessel . The plasma processing apparatus according to claim 1, wherein the partition member and the reaction vessel have conductivity and are electrically connected to each other . The partition member includes a cylindrical side wall portion, an extending portion extending from the one end of the side wall portion to the reaction chamber side by a predetermined length, and extending from the other end of the side wall portion to the side wall of the reaction vessel. The plasma processing apparatus according to claim 6 , further comprising a connection portion that connects the side wall portion and the reaction vessel . The reaction vessel is partially sealed with a sealing member,
  The plasma processing apparatus according to claim 1, wherein a part of the partition member is in contact with the sealing member. The plasma processing apparatus according to claim 1, wherein the partition member is hollow, and includes means for supplying a cooling medium to the hollow portion.

Images