JPS63131519A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To improve the thermal contacting state of a tray with a first electrode by covering one of the opposed surfaces of the electrode and the tray with an elastic thermal conductive thin film. CONSTITUTION:The cause that a tray 31 is not preferably contacted with an electrode 20 is a fine irregular surface on the metal surface itself and further the gradual warpage of the tray 31. In order to prevent them, a mechanically deformable thermal conductive thin film 32 is disposed therebetween. Thus, even if surface irregularities exist on the tray 31 or the electrode 20, they can be held in a thermally contacted state by deforming the thin film 32, and since the film 32 itself has good thermal conductivity, heat is preferably transferred from the tray 31 to the electrode 20. As a result, the tray 31 is sufficiently cooled to enhance the cooling efficiency of a substrate to be treated.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a dry etching apparatus, and particularly aims to improve the thermal contact state between a tray on which a substrate to be processed is placed and an electrode. The present invention relates to a dry etching device.

(Prior Art) In recent years, reactive ion etching has been mainly used for microfabrication for manufacturing highly integrated devices. The reactive ion etching method is: - A substrate to be processed is placed on one electrode (cathode) in a vacuum container having a pair of opposing electrodes, and a gas containing a halogen element such as CF4 is introduced into the container. In this method, high frequency power is applied between the pair of electrodes to discharge gas, and the generated ions and radicals are used to etch the substrate to be processed.

Etching apparatuses using the above method include a batch type apparatus in which, for example, 10 to 20 substrates to be processed are placed in a large chamber at a time and etched, and a batch type apparatus in which only one substrate to be processed is placed in a small chamber for etching. There is a single-wafer type device that performs this. In the future, the dimensions of LSI will become smaller and smaller, and S
The diameter of i-wafers continues to increase from 6 inches to 8 inches. Therefore, in order to uniformly form a fine pattern on the surface of a large-diameter wafer, a single-wafer type apparatus is more advantageous, and the single-wafer type two-position apparatus is gradually becoming mainstream.

As a matter of course, a single wafer type etching apparatus has a lower throughput than a batch type etching apparatus if the etching speed is the same. Therefore, in the single-wafer etching apparatus, in order to obtain a high etching rate, a method of generating high-density plasma using magnetron discharge, hollow cathode discharge, etc. is adopted.

However, since the single-wafer etching apparatus generates high-density plasma as described above, there is a problem in that the exposed portion of the cathode that is not covered with the substrate to be processed is subjected to ion bombardment and is consumed. To prevent this, a conventional method has been adopted in which the substrate to be processed is placed on a tray in advance and placed on the cathode to prevent the cathode itself from being exposed to high-density plasma. In this case, the portion of the tray surface on which the substrate to be processed does not rest is exposed to high-density plasma and is worn out, but since the tray is just a metal plate and is inexpensive, it is easy to replace. Therefore, the problem of the cathode itself having a complicated structure being consumed is solved, and the problem of the tray being consumed does not become a problem.

However, this type of device has the following problems. That is, since the substrate to be processed is exposed to high-density plasma and heated, it is necessary to cool it. In the one-tray type, the cathode is cooled and the substrate to be processed is cooled through the tray, but the thermal contact between the cathode and the tray is insufficient and the tray cannot be cooled sufficiently. In other words, metal-to-metal bonding is extremely difficult, and the tray is not sufficiently cooled, resulting in an unavoidable rise in temperature of the substrate to be processed. Then, when the temperature of the substrate to be processed increases,
The resist, which is an etching mask, may be thermally deformed, or the processed shape may change during etching. Therefore, the accuracy of etching is reduced.

(Problems to be Solved by the Invention) As described above, in the conventional single-wafer type dry etching apparatus using a tray, thermal contact between the tray and the electrode was insufficient, and it was difficult to cool the tray sufficiently. be. For this reason, the substrate to be processed cannot be cooled sufficiently, resulting in problems such as a decrease in etching accuracy.

The present invention has been made in consideration of the above circumstances, and its purpose is to improve the thermal contact between the tray and the electrode, suppress the temperature rise of the substrate to be processed, and improve processing accuracy. (Means for solving the problem) The gist of the present invention is to use a thermally conductive material that is easily deformed mechanically between the tray and the electrode in order to improve the thermal contact between the tray and the electrode. The key is to place a good thin film.

The reason why the tray and the electrode do not come into good contact is that the metal surface itself has minute irregularities and that the tray gradually warps. Therefore, by interposing the thin film between them, it is possible to improve the thermal contact between the tray and the electrode.

That is, the present invention provides a container having first and second electrodes arranged opposite to each other, means for supplying gas into the container, means for exhausting the gas in the container, and a substrate on which a substrate to be processed is placed. A dry etching apparatus comprising: a tray placed on the first electrode; means for cooling the first electrode; and means for applying high frequency power between the first and second electrodes. In this method, an elastic thin film having good thermal conductivity is coated on at least one of the opposing surfaces of the first electrode and the tray.

(Function) With the above configuration, even if there are irregularities on the tray surface or the electrode surface, the thin film can be deformed to maintain them thermally in close contact with each other.

Furthermore, since the thin film itself has good thermal conductivity, heat is transferred well between the tray and the electrode, and as a result, the tray is sufficiently cooled, making it possible to improve the cooling efficiency of the substrate to be processed.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram showing a dry etching apparatus according to an embodiment of the present invention. 10 in the figure. is a grounded vacuum chamber (container), and this vacuum chamber 10 is separated into an etching chamber 12 and a loading chamber 13 by a flange 11 and a tray 31, which will be described later. Etching chamber 12
A predetermined gas is introduced into the interior through a gas inlet 14.

Gas in the etching chamber 12 is introduced into the load chamber 13 through an opening 15 provided in the flange 11 and is exhausted through a gas exhaust port 16.

Inside the vacuum chamber 10, a cathode (first electrode) 20 is arranged at a position facing the upper wall 10a of the chamber, which acts as an anode (second electrode).

This cathode 20 is connected to a drive pipe 2 that penetrates the bottom wall of the chamber.
It is attached to the top of 1 and can be moved up and down. On the cathode 20 is a semiconductor wafer 3 as a substrate to be processed.
A tray 31 on which 0 is placed is placed. And cathode 2
0 is raised and the peripheral portion of the tray 31 is pressed against the flange 11, the inside of the chamber 10 is separated into an etching chamber 12 and a load chamber 13.

Here, a high frequency power source 23 is connected to the cathode 20 via a matching circuit 22 as shown in FIG.

Furthermore, the cathode 20 is cooled by introducing cooling water through the water cooling pipe 24. Further, the tray 31 is made of a metal plate, and the bottom surface of the tray 31 has an AI! A thin film 32 made of silicone rubber (thickness: 100 μm) in which fine powder of Cu and Cu is diffused is attached with an adhesive. Furthermore, a thin insulating layer (not shown) is formed on the upper surface of the tray 31, and the wafer 30 is thereby electrostatically chucked.

In the figure, numeral 41 is a magnetic field applying mechanism for applying a magnetic field onto the cathode 20, which is horizontally scanned or rotated. 42 is a gate valve, and the tray 31 is conveyed onto the cathode 20 via this gate valve 42. Further, 43 indicates a vacuum gauge for measuring the pressure inside the etching chamber 12, and 44 indicates an insulator.

With this configuration, after the tray 31 on which the wafer 30 is placed is transferred and placed on the cathode 20 via the gate valve 42, the cathode 20 is raised and the tray 31 is pressed against the flange 11. In this state, by introducing etching gas into the etching chamber 12 and applying high frequency power to the cathode 20, magnetron discharge is generated and the wafer 30 can be etched by high density plasma.

In this case, since the thin film 32 having good thermal conductivity and elasticity is adhered to the lower surface of the tray 31, the state of thermal contact between the tray 31 and the cathode 20 can be improved. Therefore, the wafer 30 can be sufficiently cooled through the tray 31, and the temperature rise of the wafer 30 can be suppressed to an extremely low level even during etching using high-density plasma.

Therefore, it is possible to prevent thermal deformation of the resist due to an increase in the temperature of the wafer 30, and it is possible to improve processing accuracy.

FIG. 4 is a characteristic diagram showing changes in tray temperature and wafer temperature with respect to discharge time when etching is performed using this apparatus. The discharge conditions were a flow rate of etching gas C2 of 50 [5ccffl] and a gas pressure of 5 x 10'.
[torr, high frequency power 1 [W/cM2]
And so. After the start of discharge, the temperature of the tray 31 and wafer 30 rises, but even after 5 minutes, the temperature of the tray remains approximately 30['C]
The wafer temperature is also about 70['C]. After this, the tray temperature and wafer temperature hardly change. When the wafer 30 was etched in this state using the positive resist as a mask, the resist was not thermally deformed at all and good etching characteristics were obtained.

On the other hand, when the thin film 32 described above is not applied to the back surface of the tray 31 and the tray 31 and the cathode 20 are brought into contact with exposed metal (conventional example), the tray 31 and the wafer 30
The temperature change was as shown in FIG. The temperature of the tray exceeded 40 ['C] in about 2 minutes after the start of discharge, and 6 minutes after 5 minutes.
It reaches 0 [℃]. Wafer 30 also shows a similar tendency, but
The value is about 40['C] higher than the temperature of the tray. When the wafer 30 was etched in this state in the same manner as in the example, thermal deformation of the resist was noticeable and the etching accuracy was significantly reduced.

Further, when the tray 31 is cooled and the wafer temperature is low, not only the thermal deformation of the resist is suppressed, but also the following effects can be obtained. FIG. 6(a) shows trench etching of the St substrate 61 using C2 gas and using the Si02 film 62 as a mask, with the metal of the tray 31 exposed and in contact with the cathode 20 as before. FIG. 3 is a cross-sectional view showing the etched shape when The ions reflected at the end of the mask impact the sidewalls of the trench, resulting in so-called gouges.

On the other hand, in the case of this example, as shown in FIG. 6(b), the etching product 5iC1x (x-1 to 4) was 5i0
2 reacts with O* produced as a result of etching the 5i02 film 62, and a deposit 63 of 5i02 is produced by a type of plasma CVD. Since this deposit 63 protects the sidewalls from reflected ions, vertical etching as shown in the figure is possible. This accumulation is
It is very sensitive to temperature and does not occur at high substrate temperatures. That is, this effect can only be obtained by improving the thermal contact between the tray 31 and the cathode 20 by depositing the thin film 32 as in this embodiment.

Thus, according to this embodiment, due to the presence of the thin film 32 adhered to the back surface of the tray 31, it is possible to make good thermal contact between the tray 31 and the cathode 20.
It becomes possible to sufficiently cool the wafer 30 placed thereon. Therefore, even during etching using high-density plasma, the temperature rise of the wafer 30 can be suppressed to a low level, thermal deformation of the resist, etc. can be prevented, and processing accuracy can be improved. Further, compared to conventional devices, there is an advantage that the device can be realized with a simple configuration that only requires the thin film 32 to be placed on the back surface of the tray 31.

Note that the present invention is not limited to the embodiments described above. For example, the thin film does not necessarily need to be deposited on the tray side, but may be deposited on the cathode (first electrode) side. Furthermore, a thin film may be applied to both the tray and the opposing surfaces of the cathode.

Further, the thin film material is not limited to the same as in the embodiments, but may be any material that is elastic and has good thermal conductivity, and can be changed as appropriate depending on the specifications. For example, it is possible to use an organic polymer material in which fine metal powder or graphite powder is diffused, or an a-machine polymer material in which fine ceramic powder is diffused.

Furthermore, by using a thin film material with good electrical conductivity, it is also possible to reduce power loss between the cathode and the tray.

Further, the means for bringing the tray and the cathode together is not limited to mechanical means, and may be an electrostatic chuck. Furthermore, although the embodiments have been described using magnetron discharge, it is of course applicable to dry etching using ordinary discharge. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, the thermal contact between the tray and the first electrode can be made good, and the substrate to be processed placed on the tray can be sufficiently heated. can be cooled to Therefore, it is possible to prevent deformation of the resist due to a rise in temperature of the substrate to be processed, and it is possible to improve processing accuracy.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic configuration diagram showing a dry etching device according to an embodiment of the present invention, FIG. 2 is a diagram more specifically showing the cathode structure used in the above device, and FIG. is a diagram more specifically showing the tray structure used in the above device, and FIGS. 4 to 6 are for explaining the effects of the above embodiment, respectively.
FIG. 4 is a characteristic diagram showing the temperature change of the wafer and tray with respect to the discharge time in the example, FIG. 5 is a characteristic diagram showing the temperature change of the wafer and tray with respect to the discharge time in the conventional example, and FIG. 6 is the conventional example and the example. FIG. 3 is a cross-sectional view showing an etched shape in an example. 10... Vacuum chamber (capacity 3), 10a... Upper wall (
(second electrode), 11... flange, 12... etching chamber, 13... load chamber, 14... gas inlet,
16... Gas exhaust port, 20... Cathode (first electrode)
, 23... High frequency power, 3G... Wafer (substrate to be processed), 31... Tray, 32... Thin film, 41...
Magnetic field application mechanism. Applicant's representative Patent attorney Takehiko Suzue Discharge time (current) - Figure 4 Power supply time (minutes) - Figure 5 (a) (b) @ Figure 6

Claims (6)

[Claims] (1) A container provided with first and second electrodes arranged oppositely, a means for supplying gas into the container, a means for exhausting the gas in the container, and a substrate to be processed placed thereon. Said first
A dry etching apparatus comprising: a tray placed on the first electrode; a means for cooling the first electrode; and a means for applying high frequency power between the first and second electrodes. 1. A dry etching apparatus comprising: an elastic thin film having good thermal conductivity coated on at least one of the opposing surfaces of the electrode and the tray. (2) The dry etching apparatus according to claim 1, wherein the thin film is made of synthetic resin. (3) The dry etching apparatus according to claim 2, wherein the thin film is made of an organic polymer material in which fine metal powder or fine graphite powder is diffused. (4) The dry etching apparatus according to claim 2, wherein the thin film is made of an organic polymer material in which fine ceramic powder is diffused. (5) The dry etching apparatus according to claim 2, wherein the thin film is made of rubber having good thermal conductivity. (6) The dry etching apparatus according to claim 1 or 2, wherein the thin film has good electrical conductivity.