JPH05335275A - Dry etching device - Google Patents

Abstract

PURPOSE:To realize anisotropic etching of a large area while allowing a large number of substrate treatments by setting-up a plurality substrates to be treated during plasma discharge to be formed between the electrodes of a pair of parallel flat plates so as to supply power to a third electrode set up close to this substrate. CONSTITUTION:A container 5 having a pair of discharge electrodes 1, 2 and the substrate suscepters 4 able to set up the substrates 3 to be treated between these electrodes is located inside an etching reaction chamber 6. A plurality of substrates 3 to be treated are set up near the positive columns of plasma discharge generated by the discharge electrodes 1, 2 by means of the substrate suscepters 4. These substrate suscepters are connected to power supply 8 for bias separate from power supply 7 for discharge connected to the discharge electrode so as to provide a bias electric field to the substrates to be treated as a third electrode. Thereby, uniform anisotropic etching having a large area can be realized.

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, which can process a large area and a large number of substrates.

[0002]

2. Description of the Related Art As a dry etching technique by a gas phase etching reaction, a plasma etching method in which a high frequency power or an electromagnetic wave power is applied alone or a magnetic field or a bias electric field is added to these powers is generally known and put to practical use. .. Among these, the most common apparatus is one in which a parallel plate type discharge electrode is used, a substrate to be processed is placed on one of the electrodes, and high frequency power is applied between the electrodes to perform dry etching.

In the recent semiconductor manufacturing technology, the required semiconductor products are highly integrated and the required area is very small. Therefore, the patterning of elements and wiring portions requires accuracy of micron order or less. .. Therefore, an anisotropic etching technique is required instead of an isotropic technique.

Regarding anisotropic etching, RIE mode etching and ECR etching are known. The RIE mode etching realizes anisotropic etching by applying a bias electric field to the substrate to be processed from the outside or inside of the parallel plate type dry etching technique described above. Anisotropic etching is realized by irradiating a substrate to be processed with an activated etching gas using a plasma shower generated by cyclotron resonance (ECR).

[0005]

As the degree of integration of the dry etching process in the manufacturing process of a semiconductor device is improved, high-speed processing, high anisotropy, high aspect ratio and high selectivity are required as described above. It started to come. The conventional RIE mode or ECR mode etching cannot meet such requirements.

That is, in the RIE mode, it was not possible to achieve both a high-density plasma state and a low ion energy state in the state of active species during plasma discharge. In other words, when high energy is applied to the reactive substrate in order to realize high-speed processing, a large number of those having high ion energy will be present in the plasma, which will damage semiconductor elements and materials on the substrate to be processed. It will lead to giving. As shown in the schematic cross-sectional view of the RIE mode etching apparatus shown in FIG. 2, the substrate 100 to be processed is placed on one side of the parallel plate electrodes 101, and a bias electric field is applied to this substrate to the outside. The RIE mode is set by applying a bias voltage from another power source or generating a self-bias electric field. Since the substrate 100 is placed on the electrode 101 as described above, the size itself of the electrode 101 has to be enlarged in order to meet the demand for a large area and a large amount of processing. This leads to an increase in the floor area of the entire apparatus, and it has not been possible to meet the user's request.

On the other hand, in ECR etching, EC
Since the reactive ion shower from the R reaction region portion is used, this shower needs to be uniformly distributed on the surface of the substrate to be processed, but in order to ensure this uniformity,
The device needed to be upsized and similarly did not meet the user's wishes. That is, it has a function of separately controlling the plasma energy and ion energy in the plasma necessary for controlling anisotropic etching, and has a large area,
An apparatus for achieving anisotropic etching capable of processing a large number of substrates has been desired.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above problems and relates to an etching apparatus capable of processing a large number of substrates in a large area and realizing a good anisotropic processed shape. .. That is, a plurality of substrates to be processed are placed in a plasma discharge formed between a pair of parallel plate electrodes, and a third electrode is placed close to the substrates.
It is a plasma etching device that can apply a bias electric field to this substrate by supplying electric power to the electrodes of, and has means for supplying an etching reaction gas from the vicinity of these multiple substrates.

FIG. 1 shows a schematic diagram of a typical configuration of the etching apparatus of the present invention. Further, FIG. 3 shows a schematic view of the vicinity of the container described in FIG. A container 5 having a substrate susceptor 4 is provided in the etching reaction chamber 6 so that the substrate 3 to be processed can be placed between the pair of discharge electrodes 1 and 2. Naturally, the reaction chamber 6 has an evacuation system so that it can be maintained in a reduced pressure state, and also has a system for supplying an etching reaction gas. A plurality of substrates 3 to be processed are installed by the substrate susceptor 4 in the vicinity of the positive column region of the plasma discharge generated by the discharge electrodes 1 and 2. The substrate susceptor 4 has a discharge power source 7 connected to the discharge electrodes. Is connected to another bias power source 8 and is configured so that a bias electric field can be applied to the substrate to be processed as the third electrode.

The distance between the hood and the container is controlled so that the plasma generated by the discharge electrodes 1, 2 exists in the space 9 surrounded by the electrode hoods 10, 11 and the container 5, whereby the reaction chamber 6 is controlled. It is designed so that plasma does not spread near the inner wall of the.

Since a plurality of substrates 3 to be processed can be provided between the discharge electrodes 1 and 2 in this manner and the etching process can be performed simultaneously,
Large-scale processing of substrates is possible. Further, by widening the distance between the electrodes 1 and 2, it is possible to increase the area of the substrate, and it is possible to process the large area substrate without increasing the floor area of the apparatus.

The substrate supplying means is in contact with the container 5 so that the reactive gas for etching is supplied to the vicinity of the substrate 3 to be processed from any one of the side surfaces of the container 5, that is, the four surfaces without the discharge electrodes. The container 5 is provided at or near the hole, and a hole 13 is provided in the container 5 in the vicinity thereof so that the reactive gas can be introduced into the reaction space 9. Although the gas supply means is not shown in FIGS. 1 and 3 because the directions shown in the drawings are different, the gas supply means, for example, a gas nozzle is installed near the position corresponding to the hole 13 in FIG. There is.

With the above structure, the reactive gas for etching is supplied from the vicinity of the substrate to the discharge space and thereafter spreads throughout. In a conventional RIE etching apparatus, a substrate is usually installed on the cathode side, and a reactive gas is supplied from an electrode on the anode side. At this time, the vicinity of the electrode is a portion where most active species in the ionized state exist when the reactive gas is activated, and the conventional apparatus always passes through this portion to supply the gas.

On the other hand, according to the structure of the present invention, the gas does not pass through the region near the electrode where the degree of ionization is high, so that the polymer formed by the elements such as carbon and sulfur contained in the etching gas is excessive. Will not do. Therefore, in the vicinity of the substrate to be subjected to the etching reaction, a large amount of a suitable polymer and active species such as a halogen element necessary for the etching reaction are present, and the etching rate is improved without adding excessive discharge power. It is something that can be done. In addition, since the bias voltage applied to the substrate can be controlled independently of the discharge power through the third electrode, the anisotropic etching shape can be controlled very easily.

As described above, since it is not necessary to apply excessive electric discharge power to the reactive gas in order to increase the etching rate, the amount of ions existing in the activated plasma state is reduced, whereby the etching process is performed. The subsequent ion damage can be reduced, and the present invention can be positively applied to the processing around the gate insulating film of the insulating gate type semiconductor device. The present invention will be described below with reference to examples.

[0016]

EXAMPLE An example of a positive column type etching apparatus of the present invention is one having a structure around a reaction chamber as shown in FIG. Further, FIG. 3 is a schematic view of the periphery of the container for holding the substrate near the positive column of the plasma discharge, and this container is just arranged in the space sandwiched by the parallel plate electrodes of FIG. The substrate can be arranged in the positive column region of the plasma discharge.

In the etching apparatus of the present invention, the plasma discharge is confined within the outer walls of the electrode hoods 10 and 11 and the container 3 in order to perform a uniform and stable etching process on a large area. There is.
Therefore, the electric potentials of the electrode hoods 10 and 11 and the container 5 are kept at the ground potential. On the other hand, the substrate susceptor 4 included in the container 5 and holding the substrate 3 is separated from the potential of the outer wall of the container 5, and is realized by the floating potential or the bias power supply 8 connected to the substrate susceptor 4. It has a structure in which it can be held at a potential and thus can function as a third electrode for applying a bias potential to the substrate.

Therefore, the container 5 and the substrate susceptor 4 are
Insulating ceramics or a polymer material is arranged at the joint of, or the outer frame of the container 5 has a double structure and the outside is ground potential and is electrically separated from the inner frame, and the substrate susceptor 4 and A similar structure can be achieved by connecting the bias external power supply 8.

In the positive column type etching apparatus having the structure near the reaction chamber 6 as described above, the reactive gas is not supplied from the vicinity of the parallel plate electrodes 1 and 2 to the substrate 3 side, but the side surface of the container 5. On at least one side of
After passing through the holes 13 for gas supply, the reactive gas is first supplied to the vicinity of the substrate to be processed, activated in the positive column region in the vicinity, and then spreads throughout the reaction space.

At this time, it is also possible to introduce the auxiliary gas for reaction from the vicinity of the electrodes 1 and 2 at the same time. The auxiliary gas contains a gas or a molecule having a function of promoting the reaction between the object to be processed and the reactive gas to become a gas state, and carbon atoms for realizing anisotropic etching. Gases containing are also included. That is, when a halogenated hydrocarbon gas is introduced as a reactive gas near the substrate 3 to be processed, the auxiliary gas is a gas such as hydrogen or oxygen, but the reactive gas is anisotropic such as chlorine gas. When a gas that does not contain carbon molecules that realizes the property is supplied from the vicinity of the substrate to be processed, a gas containing carbon molecules is supplied from the vicinity of the electrode, and the amount is controlled to control the degree of anisotropy and etching rate. Can be controlled, which is a great advantage in actual work.

An example of plasma anisotropic etching treatment using silicon having the above structure and using silicon as an object to be treated is shown below. The reactive gas used is CF ₄
It is 100%, and this gas is supplied from the hole 13 of the container 5 near the substrate to be processed, and 13.56 is supplied to the discharge electrodes 1 and 2.
The phase of the power having a frequency of MHz was adjusted by two different power supplies 7 and applied to generate plasma discharge. Further, in order to exhaust gas from the surface opposite to the surface of the container 5 in which the hole 13 is formed, a hole for exhausting gas is also formed in this surface, and unnecessary gas after the reaction is actively discharged.

In the case of the present invention, the amount of the low-ion energy reactive species in the vicinity of the substrate to be processed is larger than that in the conventional apparatus, and the polymer such as carbon (mainly formed in the active region of the reaction near the electrode). The amount of ()) present in the vicinity of the substrate to be processed is reduced, the contact cross-sectional area between silicon and the reactive species is substantially increased, and it is possible to realize a process with a small ion damage and a high etching rate.

Specifically, an etching rate of 1500 Å to 5000 Å / min can be realized, and in comparison with the conventional apparatus,
We were able to achieve at least twice the speed. In addition, from the vicinity of the discharge electrodes 1 and 2, 5 to 10 oxygen is used as an auxiliary gas.
%, The speed could be further improved by 10 to 20%.

The cross section of the pattern after the etching process is SEM.
When the cross-sectional shape was observed from the photograph, it was found that good anisotropic etching with a high aspect ratio was realized.

[0025]

By adopting the structure of the present invention, it is possible to realize uniform anisotropic etching over a large area and to obtain a sufficiently high etching rate. In order to realize anisotropic etching, it is necessary to proceed with etching while forming a polymer film on the side wall of the pattern of the object to be etched. At this time, the etching rate is determined by the attachment rate of the polymer film (having a function of suppressing the etching reaction) attached to the surface to be etched and the reaction rate of the object to be etched and the reactive species after removing the polymer film.

With the structure of the present invention, the concentration of the polymer around the substrate to be processed becomes lower than that of the conventional apparatus, and the amount of the polymer can be controlled by changing the gas supply position and the amount thereof. Therefore, anisotropic etching with a high etching rate could be realized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of the vicinity of a reaction chamber of an etching apparatus of the present invention.

FIG. 2 shows a schematic sectional view of a conventional etching apparatus.

FIG. 3 is a schematic view of the vicinity of the container of the etching apparatus of the present invention.

[Explanation of symbols]

 1 ... electrode 2 ... electrode 3 ... substrate 4 ... substrate susceptor (third electrode) 5 ... container

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Abe, 398 Hase, Atsugi, Kanagawa Prefecture, Semi Conductor Energy Laboratory Co., Ltd. (72) Inventor, Hideki Ii, 398, Hase, Atsugi, Kanagawa, Ltd.

Claims (4)

[Claims] 1. A plurality of substrates to be processed are placed during a plasma discharge formed between a pair of parallel plate electrodes, a third electrode is placed close to the substrates, and a power is supplied to the third electrode. By supplying a bias electric field to the substrate, the plasma discharge is present in a reaction space surrounded by an electrode hood and a container, and the substrate to be processed is a positive electrode of the plasma discharge. An etching apparatus characterized in that it is arranged near a pillar by a substrate susceptor that is a third electrode. 2. The electrode hood and container forming the plasma discharge space according to claim 1 are held at a ground potential or a certain potential, and only the substrate susceptor is connected to an external power source as a third electrode. Etching equipment characterized by. 3. A plurality of substrates to be processed are placed during a plasma discharge formed between a pair of parallel plate electrodes, a third electrode is placed close to the substrates, and a power is applied to the third electrode. A plasma etching apparatus capable of applying a bias electric field to the substrate by supplying the etching gas, the etching apparatus having a means for supplying an etching reaction gas in the vicinity of the substrate. 4. The etching apparatus according to claim 3,
The plasma discharge exists in a reaction space surrounded by an electrode hood and a container, and the substrate to be processed is arranged near a positive column of the plasma discharge by a substrate susceptor which is a third electrode. ..