JPH0722393A - Dry etching equipment and method - Google Patents

Abstract

PURPOSE:To enable a dry etching equipment to be enhanced in etching selectiv ity to a base material and set constant in etching rate independent of the diame ter of a hole by a method wherein a cooling means which is provided in a reaction chamber and kept at a specific temperature and a transfer means which transfers the cooling means between the reaction chamber and an outside of the chamber keeping the reaction chamber in vacuum are provided. CONSTITUTION:Gas or liquid introduced through a grounded piping 43 is introduced into a temperature change section 40 through a piping provided inside a multi-joined robot 44, whereby the temperature change section 40 can be set in a temperature range of 0 deg.C to 100 deg.C, so that an opening 0.6mum in diameter, 2mum in depth, and above 3.4 in aspect ratio can be formed, and furthermore even if openings different in aspect ratio are mixedly present, the openings can be etched well. The temperature change section 40 can be vacuum- transferred between an etching chamber 11 and a load lock chamber 45 through the multi-joined robot 44 and the opening or the close of a shutter 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus and a dry etching method, for example, a dry etching apparatus and a dry etching method for a silicon oxide film.

[0002]

2. Description of the Related Art Conventionally, a reactive ion etching method has been used for etching an electrode material such as polycrystalline silicon or a silicon oxide film. The reactive ion etching method is
A substrate to be processed, for example, a substrate on which a thin film to be etched is formed, is placed in a vacuum reaction vessel equipped with a pair of parallel plate electrodes, a reaction gas is introduced, and then the gas is discharged by applying high-frequency power, This is a method of etching a substrate to be processed using gas plasma generated by this discharge. In addition to this reactive ion etching method, there are etching methods such as a plasma etching ECR type dry etching method, an ion beam etching method, and a photoexcited etching method. These etching methods are also activated on a substrate to be processed in a vacuum reaction container. Etching is performed by chemically or physically acting the ions of the reaction gas described above, and in this respect, it may be considered similar to the reactive ion etching method.

Gases containing carbon and fluorine, such as C ₂ F ₆ , CF ₄ , and CHF ₃ , are usually often used as reaction gases for etching silicon oxide films. For example, CHF ₃
When gas is used to open a contact hole on a Si substrate having a silicon oxide film formed on the surface of the substrate to be processed, CF ₃ radicals generated by discharge are adsorbed on the surface of the substrate to be processed. CF ₃ adsorbed on the surface of the silicon oxide film is dissociated into C and F by ion bombardment, F reacts with Si in the silicon oxide film to produce a volatile substance SiF ₄ , and C is contained in the silicon oxide. It reacts with O to generate CO and the etching proceeds. On the other hand, CF ₃ adsorbed on Si
Is drawn out of F by H, and mainly CF _x (x = 0 to 0
A polymerized film (fluorocarbon film) composed of 2) is formed.
Since this polymerized film suppresses etching, etching does not proceed unlike the silicon oxide film. As a result, it becomes possible to selectively etch silicon oxide with respect to Si.

On the other hand, semiconductor integrated circuits such as DRAMs,
As the degree of integration increases in non-volatile memory, etc., when etching a silicon oxide film for forming contact holes, etc., a high selection ratio with respect to the underlying Si is required. The formation of deep, high aspect ratio apertures is required. However, when a contact hole is etched using CHF ₃ gas as an etching gas in a magnetron RIE device known as reactive ion etching using high-density plasma, as shown in FIG.
It becomes a characteristic diagram like. That is, FIG. 12 is 2.0 μm
A pattern having a diameter of 1.2 to 1.6 μm formed on a thermal oxide film having a film thickness, and after etching to a depth of about 1 μm, the cross section was observed with an electron microscope to examine the relationship between the etching depth and the hole diameter. Is. At this time, when the CHF ₃ flow rate was kept constant at 200 SCCM, the anode temperature was 60 ° C and the cathode temperature was 20 ° C,
As the hole diameter becomes smaller, the etching rate decreases and the etching depth decreases. In particular, when the hole diameter was 1 μm or less, the etching depth drastically decreased, and etching with a depth of 1 μm became impossible. That is, when the hole diameter is 1 μm or less, it is difficult to form a contact hole having an aspect ratio of 1 or more. This was the same tendency even when the flow rate of CHF ₃ was 100 SCCM.

Furthermore, when forming openings having different diameters, the etching rate changes depending on the hole diameter. That is, the etching rate of the small-diameter opening is smaller than the etching rate of the large-diameter opening. For this reason, if etching is performed under the conditions for etching a large-diameter hole as designed, the small-diameter hole will not reach the underlying layer. However, there was a problem that the overetching occurred.

Further, since a gas containing C and F such as CFC gas is used in the conventional dry etching of a silicon oxide film, a fluorocarbon film containing an element in the gas is deposited on the inner wall of the reaction vessel of the etching apparatus during etching. It is inevitable. Then, as the etching is repeated, the fluorocarbon film peels off, which causes a pattern defect of the substrate to be processed. In order to avoid this, the device is usually stopped at regular intervals of operation and the cleaning process of the reaction container is introduced, but since cleaning requires a large amount of time,
There is a problem that the throughput of the device is significantly reduced.

[0007]

As described above, in the conventional dry etching of a silicon oxide film or the like, when a contact hole having an extremely small diameter and a large aspect ratio of 1 or more is opened, the etching rate is low, so that the underlying layer is not etched. There was a problem that did not reach. In addition, when forming apertures with different diameters, the etching rate changes depending on the size of the hole diameter, and the etching rate for small diameter holes decreases with respect to the etching rate for large diameter holes. If the etching conditions for a small opening are set, there is a problem that the base material on the bottom of the hole having a large diameter is etched. Furthermore, since CFC gas is used, during etching,
The fluorocarbon film is deposited on the inner wall of the reaction vessel of the etching device. Then, as the etching is repeated, the fluorocarbon film peels off, causing a pattern defect. In order to avoid this, the apparatus is stopped every fixed operating time and the cleaning process of the reaction container is introduced. However, since cleaning requires a lot of time, there is a problem that the throughput of the apparatus is significantly reduced. there were.

The present invention has been made in view of the above circumstances, and an object thereof is to have a high selection ratio with respect to a base material, and to have a constant etching rate regardless of the hole diameter size. An object of the present invention is to provide a dry etching apparatus and a dry etching method capable of forming a high aspect ratio opening. Another object of the present invention is to provide a dry etching apparatus equipped with a mechanism in which a film does not deposit on the inner wall of a reaction container in order to shorten the time required for the cleaning process of the dry etching apparatus and significantly improve the throughput.

[0009]

In the first aspect of the present invention for solving the above-mentioned problems, means for accommodating a substrate to be processed in an airtight reaction container, and means for introducing etching into the reaction container. In a dry etching apparatus for etching the substrate to be processed by using the gas, a cooling unit provided in the reaction container and kept at 0 ° C. or lower, and a cooling unit while keeping the reaction container vacuum. There is provided a dry etching apparatus provided with means for transferring the gas between the inside and outside of the reaction container.

In the second aspect of the present invention, means for accommodating the substrate to be processed in the airtight reaction container, means for introducing gas into the reaction container, and etching the substrate to be processed using the gas. In the dry etching equipment
A cooling mechanism provided in the reaction vessel and set in a temperature range of −100 ° C. to 0 ° C., and a cooling mechanism provided adjacent to the reaction vessel and having the cooling mechanism in the reaction vessel through a shutter, the reaction vessel (EN) Provided is a dry etching apparatus comprising: a load lock chamber having means for loading and unloading while maintaining a vacuum inside.

Further, in the third aspect of the present invention, plasma is generated, and the plasma is generated in the vicinity of the generated plasma in a reaction vessel equipped with a cooling means, and a silicon substrate or a silicon oxide film is formed on the silicon film. Is formed and a substrate to be processed having a mask pattern formed on the silicon oxide film is housed, a step of introducing a gas containing at least carbon and fluorine into the reaction vessel, the gas is made into plasma, and Forming a hole in the silicon oxide film by selective etching of the silicon oxide film with respect to the silicon substrate or the silicon film along a mask pattern, and during the selective etching, the cooling means is set to −100 ° C. to 0 ° C. By setting the temperature to ℃, the opening is adjusted so that the ratio of the etching depth of the silicon oxide film to the opening diameter becomes 4 or more. It provides a dry etching method which is characterized in that formed.

[0012]

[Function] In dry etching for forming a contact hole or the like in a silicon oxide film or the like, the etching rate of the silicon oxide film changes depending on the size of the hole diameter of the contact hole, and the etching rate of the hole with a small diameter is When the contact holes have a smaller diameter or a different aspect ratio than the contact holes, there is a problem that the contact holes with a small diameter or a large aspect ratio do not reach the base because the etching rate is low. The reason why the etching rate of the small holes decreases is that the fluorocarbon film is thickly deposited on the bottoms of the small holes to suppress the etching. For example, when a fluorocarbon gas used as an etching gas, for example, a mixed gas of CF ₄ gas and hydrogen gas is discharge-excited, CF ₄ is ionized to generate CF ₃ and F, and H ₂ is ionized to generate H. To be done. Further, CF _x (x = 0 to 2) is generated due to the effect of extracting F by the generated H.
Although CF ₃ has a low probability of adhesion at room temperature, it has a high probability of adhesion at low temperatures, and therefore tends to adhere to low temperature parts. On the other hand, CF ₃
At the same time, CF _x (x = 0 to 2) generated in plasma
Has a high adhesion probability, and the easiness of adhesion hardly changes even when the temperature is lowered. Therefore, when a low temperature part is provided in the reaction vessel as in the present invention, a large amount of CF ₃ is attached to the low temperature part, and the CF _x (x = 0 to 2) concentration in the plasma is relatively increased. The amount of CF _x (x = 0 to 2) attached on the wafer surface depends on the surface shape. That is, since the amount of adhesion is reduced at the bottom of the hole having a small diameter, the fluorocarbon film that suppresses etching is not formed at the bottom of the hole having a small diameter. Therefore, by providing a low temperature section in the reaction vessel,
The etching rate of holes with a small diameter did not decrease, and it became possible to open holes with a high aspect ratio.

Further, even if the etching rate of the hole having a small diameter is significantly reduced as compared with the etching rate of the hole having a large diameter, the etching rate of the hole having a small diameter can be obtained by providing a low temperature portion in the reaction vessel. No longer drops. The above-mentioned effects are obtained as a result of the inventors of the present invention earnestly devising and conducting experiments.

Furthermore, in the dry etching of the silicon oxide film, a fluorocarbon film is deposited on the inner wall of the reaction vessel when, for example, CFC gas is used during etching.
By providing the low temperature part in the reaction container, the amount of fluorocarbon film deposited in the low temperature part is increased, and the amount deposited on the inner wall of the reaction container is drastically reduced. Therefore, it is possible to remove most of the fluorocarbon film deposited in the reaction container by transferring it to the outside of the reaction container while maintaining it in vacuum using a load lock or the like and cleaning it in the atmosphere while using this load lock or the like. Become. further,
While the low temperature part is being cleaned, the spare low temperature part provided can be used to continue the etching without stopping. By this method, the cleaning time of the device can be greatly shortened, and the throughput of the device can be significantly increased.

[0015]

Embodiments of the dry etching apparatus and the dry etching method according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a dry etching apparatus according to an embodiment of the present invention. Reference numeral 10 in FIG. 1 denotes a grounded reaction vessel forming an etching chamber 11,
A cathode 20 is installed at the bottom of the reaction container 10.
A high frequency power of 13.56 MHz is applied to the cathode 20 from a power supply 22 via a matching circuit 21. Also,
The cathode 20 is cooled by a coolant through a cooling pipe 23, and this cooling pipe 23 is used as a lead for applying high frequency power. A copper plate 25 sandwiched between polyimide films 24 is mounted on the cathode 20, and a voltage of 4 kV is applied to the copper plate 25 from a power source 26, which is insulated from the cathode 20 by an insulator, through a lead. Thus, the substrate 30 to be processed is electrostatically adsorbed on the cathode 20.

Further, the gas inlet 1 is provided in the etching chamber 11.
Reactive gas is introduced from 2 and further etching chamber 11
The gas inside is exhausted from the exhaust port 13. The anode 31 facing the cathode 20 is a part of the reaction vessel 10, is disposed on the upper wall of the etching chamber 11, and is grounded. This anode 3
A magnetic field generator including a plurality of permanent magnets 14 and a drive mechanism 15 for the permanent magnets is installed outside the reaction vessel 10 on the upper part of the reaction vessel 10 to generate a magnetic field in a space facing the cathode 20 and the anode 31. In FIG. 1, reference numeral 27 denotes a gas introduction tube for introducing gas into the back surface of the substrate 30 to be processed for heat conduction, and 28 denotes an insulator for insulating the cathode 20 and the reaction vessel 10.

The load lock chamber 45 has an exhaust port 41. The temperature of the temperature-variable object (temperature-changing part) 40 is controlled by the gas or liquid introduced through the grounded pipe 43 through a pipe (not shown) in the articulated robot 44.
The temperature changing part 4 is directly introduced by being introduced into the temperature changing part 40.
The temperature of 0 is adjusted. In addition, the airtightness between the etching chamber 11 and the load lock chamber 45 is ensured by the shutter 4
Protected by 2. The shutter 42 is opened / closed and the articulated robot 44 is used to form a structure in which the temperature changing unit 40 can vacuum convey between the etching chamber 11 and the load lock chamber 45.

The temperature of the temperature changing part 40 is indirectly controlled by heat conduction by a multi-joint robot in which the gas or liquid is made of a material having a high heat conductivity such as aluminum or alumite. May be temperature controlled.

When cooling the temperature changing section 40, the temperature changing section 40 may be directly cooled by enclosing dry ice or the like in the temperature changing section 40. Here, using the magnetron type dry etching apparatus, high-frequency power of 800 W is applied between the electrodes, the cathode temperature is 20 ° C., the temperature change part temperature is 60 ° C., the total flow rate of CF ₄ gas and H ₂ gas is 100 SCCM,
When the etching rate of Si and SiO ₂ when the silicon oxide (SiO ₂ ) film on the silicon (Si) substrate is etched by changing the flow rate ratio of H ₂ under the condition of pressure of 40 mTorr is as shown in FIG. It became a characteristic diagram. In the figure, the vertical axis represents the etching rate and the horizontal axis represents the hydrogen flow rate ratio. As the hydrogen flow rate ratio increases, the etching rate of SiO ₂ decreases slightly. On the other hand, the etching rate of Si decreases greatly depending on the hydrogen flow rate ratio. For example, hydrogen flow rate 5
At 5%, a large SiO ₂ / Si selection ratio of about 35 is obtained. FIG. 3 shows the dependence of the etching depth on the hole diameter when the etching time is 1 minute. When CF _{4 is} 100%, the etching rate hardly depends on the hole diameter, but as shown in FIG. 2, the selection ratio is only 5. That is, when the H ₂ flow rate ratio is set to 30% or more in order to obtain a high selection ratio, the etching rate of the contact of 0.4 μm diameter is significantly reduced as compared with that of 0.5 μm diameter or more.

Then, the temperature of the temperature changing section 40 was changed to examine the etching characteristics. FIG. 4 shows the temperature of the temperature changing section 40 and SiO.
₂ shows the relationship between etching rates. A mixed gas of CF ₄ and H ₂ is used as an etching gas, and the flow rate ratios C
F ₄ 60SCCM, H ₂ 40SCCM, and pressure was 40 mTorr. As can be seen from FIG. 4, the etching rate of SiO ₂ is slightly increased when the temperature of the temperature changing portion 40 is 0 ° C. or lower.
The etching rate of i has almost no temperature dependence. Pair S
The i-selection ratio slightly rises below 0 ° C. in the temperature changing section 40.

Next, the effect of the embodiment of the dry etching method using the dry etching apparatus of the present invention will be described with reference to FIG. FIG. 5 is a characteristic diagram showing the hole diameter dependence of the etching depth in one minute of etching when the temperature of the temperature changing portion 40 is changed. When the temperature of the temperature changing portion 40 is 60 ° C., the etching rate of the contact hole having a hole diameter of 0.4 μm is 0.5 μm.
Significantly lower than m or more. On the other hand, 0 ° C and -35
At 0 ° C., the etching rate for contacts with a hole diameter of 0.4 μm does not decrease as compared with that for 0.5 μm or more. Furthermore, -150
At 0 ° C., it was again observed that the etching rate of the 0.4 μm hole diameter contact significantly decreased as compared with the hole diameter of 0.5 μm or more. Similar to the case of 60 ℃ near -150 ℃ SiO
₂ It is considered that the sharp decrease in etching depth was observed for the following reasons. That is, CF _x (x = 0 to 2) exists in the temperature-changing part due to the high probability of adhesion originally due to the low temperature of 0 ° C. or lower, but if the temperature is further lowered, the reactivity becomes low. Lower, eg -15
It is considered that the polymerized film does not become a polymerized film near 0 ° C. and is easily desorbed (migration). Therefore,
When etching a hole such as a contact hole having a hole diameter of 0.5 μm or less, the temperature of the temperature changing section 40 of the apparatus of the embodiment of the present invention described above is set to −150 ° C. to 0 ° C.
_No sharp decrease in the etching depth of ₂ .

FIG. 6 is a view showing the etching shape when the temperature of the temperature changing section 40 is changed. At this time, the substrate used has an etching shape of a substrate in which a SiO ₂ film having a film thickness of 2 μm is deposited on Si by CVD and a resist pattern is formed thereon. Under the conditions of the temperature of the temperature changing section 40 shown in FIGS. 6A and 6B of 160 ° C. and 60 ° C., when the hole diameters are 0.4 μm and 0.6 μm, the fluorocarbon is formed on the bottom of the SiO ₂ hole during etching. Polymerized film is deposited,
Etching has stopped. On the other hand, FIG.
Shown in (d) and (e). Temperature of the temperature changing section 40 0 ℃, -3
Under the conditions of 5 ° C. and −100 ° C., the fluorocarbon polymer film was not deposited thickly on the bottom of the hole, and thus the etching was not stopped halfway and the etching was performed normally. Further, when the temperature is further reduced to the temperature of the temperature changing section 40 shown in FIG. 6 (f), which is −150 ° C., the hole diameters are 0.4 μm and 0.6 μ again.
In the case of m, it was confirmed that the fluorocarbon film was deposited on the bottom of the SiO ₂ hole during the etching.

As shown in FIG.
It will be described with reference to FIGS. 7 to 9 that good etching can be performed by setting the temperature between −150 ° C. Figure 7
FIG. 4 is a characteristic diagram showing a change in sticking probability of CF ₃ and CF _x (x = 0 to 2) with respect to a temperature of a temperature changing portion. From this figure CF
_{In the case of 3,} the sticking probability of the temperature changing portion 40 increases as the temperature of the temperature changing portion decreases. The adhesion probability is 0.5 or lower at 20 ° C. or higher, but becomes 0.8 or higher at 0 ° C. or lower. On the other hand, CF _x (x =
In the case of 0 to 2), there is little change with respect to the temperature of the temperature changing part and the probability of adhesion is high. It can be seen that the adhesion probability slightly decreases above 60 ° C, but is 0.8 at 160 ° C.

Next, the Si sample substrate 50 having holes having different opening diameters or different aspect ratios shown in FIG. 8 is installed in the temperature changing section 40, and the fluorocarbon polymer film 51 when the temperature of the temperature changing section 40 is lowered. FIG. 9 shows the deposition shape of the above. At this time, the cathode temperature was kept constant at 20 ° C. for the experiment. Figure 9
As is clear from the above, if the temperature of the temperature changing portion 40 is set to a low temperature, CF ₃ having a low sticking probability easily sticks to the sample substrate 50. On the other hand, CF generated in plasma at the same time as CF _3
x (x = 0 to 2) originally has a high sticking probability, and the temperature change part 4
Even if 0 is a low temperature between −100 ° C. and 0 ° C., the amount of adhesion to the sample substrate 50 hardly changes. Further, even if the temperature of the temperature changing section 40 is lowered to about −150 ° C., the sticking probability should hardly change. However, actually, as shown in FIG. 9F, for example, when the temperature is about −150 ° C., the polymerized film 51 is hardly formed by the reaction of CF ₃ and CF _x (x = 0 to 2). This is because CF ₃ or CF _x once adsorbed on the sample substrate 50 as described above.
It is considered that (x = 0 to 2) is in a state (migration) in which it is easily desorbed from the sample substrate 50 because the reactivity is lowered by lowering the temperature. Therefore, -15
Below 0 ° C., the amount of CF ₂ attached to the sample substrate 50 decreases.

Then, as much CF ₃ adheres to the sample substrate 50 installed in the temperature changing section 40 as CF ₃ in the plasma.
_{3 The} concentration decreases and the CF _x (x = 0 to 2) concentration relatively increases. CF _x (x = 0 to 2), which has a high probability of adhesion, adheres almost once at −100 ° C. or more once it adheres to the surface. Therefore, the adhered amount of CF _x (x = 0 to 2) depends on the surface shape, As shown in FIG. 6, during the progress of etching, the adhered amount is reduced at the bottom of small holes having a small solid angle, and it becomes difficult to form a fluorocarbon film that suppresses etching.

Therefore, the temperature changing section 40 is set to 0 ° C. to −100.
By setting the temperature within the range of ℃, the hole diameter of 0.6 (b) in FIG.
Apertures with an aspect ratio of 3 μm and a depth of 2 μm larger than 3.4 can be formed, and the aspect ratio is different from this (for example, when the hole diameter is 1.2 μm in FIG. 6, the aspect ratio is about 1.6). Even if the openings were mixed, both openings could be satisfactorily etched.

In this way, the temperature changing section 40 is set to a low temperature, especially -1.
By setting the temperature to 50 ° C to 0 ° C, CF _x (x =
0-2) The phenomenon that the SiO ₂ etching rate does not depend on the hole diameter within a specific temperature range by controlling the concentration was first discovered as a result of the inventors' earnest efforts and repeated experiments. .

Further, in the apparatus of the embodiment shown in FIG. 1, after the discharge for 20 hours, a large amount of fluorocarbon film adhered to the temperature changing section 40. Therefore, in order to wash the temperature changing section 40, the temperature was changed to the load lock chamber 45. The part 40 was vacuum transported. The temperature changing unit 40 was removed from the articulated robot 44 and washed in the atmosphere.
Meanwhile, the etching was continued without stopping the apparatus by using the spare temperature changing part of the temperature changing part 40. Discharge time 1
Even after 00 hours, almost no fluorocarbon film was deposited on the inner wall of the reaction vessel. As described above, according to the apparatus of the embodiment of the present invention, it is possible to continue the etching without stopping the operation of the apparatus and without exposing the reaction container to the atmosphere.

When performing the dry etching method according to the present invention, that is, when etching a hole such as a contact hole having an opening diameter of 0.5 μm or less or an aspect ratio of 1.4 or less, as shown in FIG. It is also possible to use an etching device. This device is different from the device of FIG. 1 in the structure of the temperature changing section 40a. That is, in this apparatus, the airtight container 10 is opened to the atmosphere when the fluorocarbon film is attached to the temperature changing portion 40a without the load lock chamber 45. The temperature changing portion 40a also functions as an anode of the counter electrode of the cathode 20 and is placed in contact therewith. In addition, the temperature changing unit 40a is set to 0.
The temperature is lowered to or below 0 ° C. by introducing the refrigerant from the cooling pipe 32a into the temperature changing section 40a and discharging it from the cooling pipe 32b so that the temperature becomes constant. and again,
The temperature changing part 40a as the anode is electrically separated from the wall of the reaction hermetic container 10 by the insulators 33 and 34. The other configuration of this dry etching apparatus is the same as that of FIG. 1, and therefore, the same reference numerals are given and shown, and the detailed description is omitted.

FIG. 10 shows the operating conditions per month of the two embodiments of the apparatus before and after incorporating the temperature changing section 40 as a cooling mechanism. The actual wafer processing time was reduced from 330 hours to 479 hours because the cleaning time was drastically reduced from 100 hours to 1 hour, and the time during which the equipment was stopped due to a trouble was reduced by half by not releasing the reaction chamber to the atmosphere. And increased 1.45 times. That is, the throughput was 1.45 times.

The present invention is not limited to the above-mentioned embodiment. For example, as an etching gas, other than CF ₄ , CHF ₃ , CH ₂ F ₂ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F can be used.
_6, C ₃ F _8, a C ₄ F _8, C ₄ F can mixed gas or to any of the gas or of these ₁₀ possible to use a mixed gas added with H _2.

Also, the oxide film to be etched can be applied to a thermal oxide film, a CVD oxide film formed in a vapor phase or a liquid phase, and the like. Further, the substrate is not limited to the silicon substrate, but may be an SOI substrate, and is also applied when a polycrystalline silicon film is formed on the substrate and an oxide film thereon is selectively etched with respect to the polycrystalline silicon film. be able to.

Furthermore, the dry etching apparatus of the present invention is not limited to the structure shown in FIG.
In short, at the time of etching, a cooling mechanism capable of cooling to 0 ° C. or less is provided so as to prevent unnecessary fluorocarbon film from adhering to the substrate 30 to be processed, and this cooling mechanism can be replaced without opening the etching apparatus to the atmosphere. If

As the dry etching apparatus, an ECR type dry etching apparatus, a plasma etching apparatus, an ion beam etching apparatus, a photo-excited etching apparatus or the like may be used in addition to the parallel plate type RIE apparatus as in the embodiment.

[0035]

As described above in detail, according to the dry etching method of the present invention, the oxide film has a high selectivity with respect to the underlying material, for example, the silicon substrate, and the etching rate of the oxide film is large. By doing so, it became possible to form a contact hole with a high aspect ratio without a sharp decrease. Further, according to the dry etching apparatus of the present invention, it is possible to shorten the time required for the cleaning step of the etching apparatus and significantly improve the throughput.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a dry etching apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the amount of hydrogen added and the etching rates of SiO ₂ and Si.

FIG. 3 shows the hole diameter and SiO when changing the amount of hydrogen added.
₂ is a characteristic diagram showing the relationship between etching depths.

FIG. 4 is a characteristic diagram showing a relationship between a temperature changing portion and a SiO ₂ etching rate.

FIG. 5 is a characteristic diagram showing the relationship between the hole diameter and the SiO ₂ etching depth when the temperature changing portion is changed.

FIG. 6 is a diagram showing an etching shape when the temperature of the temperature changing portion is changed.

FIG. 7 is a characteristic diagram showing the relationship between the temperature change temperature portion and the sticking probability.

FIG. 8 is a sectional view showing a sectional shape of a sample used.

FIG. 9 is a diagram showing a deposition shape of a fluorocarbon film on a sample when the temperature of the temperature changing part is changed.

FIG. 10 is a comparison diagram of throughputs of a dry etching apparatus according to the present invention and a conventional dry etching apparatus.

FIG. 11 is a schematic configuration diagram of another dry etching apparatus used in the dry etching method of the present invention.

FIG. 12 is a diagram showing the relationship between the etching depth of a silicon oxide film using CHF ₃ gas and the hole diameter.

[Explanation of symbols]

 10 Reaction Container 11 Etching Chamber 12 Gas Inlet 13 Exhaust Port 14 Permanent Magnet 15 Drive Mechanism 20 Cathode 21 Matching Circuit 22 Power Supply 23 Cooling Pipe 24 Polyimide Film 25 Copper Plate 26 Power Supply 27 Gas Inlet Pipe 28 Insulator 29 Insulator 30 Processed Substrate 31 Anode 40 Temperature Change Section 41 Exhaust Port 42 Shutter 43 Piping 44 Articulated Robot 45 Load Lock Chamber 50 Sample 51 Polymerized Membrane

Front page continuation (72) Inventor Haruo Okano 1 Komukai Toshiba-cho, Kouki-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research and Development Center

Claims (7)

[Claims] 1. A dry etching apparatus for accommodating a substrate to be processed in an airtight reaction container, means for introducing an etching gas into the reaction container, and a dry etching apparatus for etching the substrate to be processed using the gas, A cooling means provided in the reaction vessel and maintained at 0 ° C. or lower, and means for transferring the cooling means between the inside and outside of the reaction vessel while keeping the inside of the reaction vessel in vacuum A dry etching apparatus characterized in that 2. A means for accommodating a substrate to be processed in an airtight reaction vessel, a means for introducing a gas into the reaction vessel, and a dry etching apparatus for etching the substrate to be treated using the gas, wherein the reaction Provided in the container −
A cooling mechanism set in a temperature range of 100 ° C. to 0 ° C. and a cooling mechanism provided inside the reaction container adjacent to the cooling mechanism are carried in through the shutter while keeping the reaction container vacuum. And a load-lock chamber having a means for unloading the dry-etching apparatus. 3. The cooling mechanism is characterized in that the cooling gas or the cooling liquid introduced through a pipe passes through the multi-joint robot, and the cooling gas or the cooling liquid is introduced into the cooling mechanism. The dry etching apparatus according to claim 2. 4. The dry according to claim 2, wherein the cooling mechanism is one in which the cooling gas or the cooling liquid introduced through the pipe is indirectly cooled by heat conduction through the articulated robot. Etching equipment. 5. The dry etching apparatus according to claim 2, wherein the cooling mechanism is one in which dry ice is enclosed in the cooling mechanism. 6. A plasma is generated, and a silicon oxide film is formed on a silicon substrate or a silicon film in a reaction container equipped with a cooling means for cooling the plasma in the vicinity of the generated plasma. A step of accommodating a substrate to be processed having a mask pattern formed on a film, a step of introducing a gas containing at least carbon and fluorine into the reaction vessel, plasmaizing the gas, and applying the silicon along the mask pattern. A step of forming an opening in the silicon oxide film by selective etching of an oxide film with respect to the silicon substrate or the silicon film, and the cooling means is set to −100 ° C. to 0 during the selective etching step.
A dry etching method, characterized in that the opening is formed so that the ratio of the etching depth of the silicon oxide film to the opening diameter becomes 3 or more by setting the temperature to ℃. 7. The dry etching method according to claim 6, wherein the substrate to be processed is formed in which openings having an aspect ratio of 3 or more and openings having an aspect ratio of 3 or less are mixed.