JPS62256432A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To reduce the rate of deactivation of quasi-stable excitation species caused by collision with 3rd gas significantly and improve etching efficiency of a substrate to be treated by a method wherein, when the quasi-stable excitation species created by a quasi-stable excitation species creating part are introduced into a reaction chamber, the quasi-stable excitation species are made to react with processing gas containing halogen elements preferentially. CONSTITUTION:Gas which is made to flow out of a storage part 4 flows through a valve 5 and a mass-flow controller 6 and is converted into quasi-stable excitation species by a quasi-stable excitation species creating part 7. The quasi-stable excitation species introduced into a reaction chamber 1 from a pipe 9 is made to react with processing gas which contains halogen elements and is introduced from pipes 13 and 14 preferentially. Products produced by the reaction are successively made to react with 3rd gas gas introduced from pipes 18 and 19 and finally etch a substrate 2 to be treated placed on a substrate table 3. With this constitution, the probability of deactivation of the quasi-stable excitation species caused by the collision with the 3rd gas can be significantly reduced and etching reaction can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching apparatus used in the manufacture of semiconductor integrated circuits, and more particularly, to a dry etching apparatus suitable for processing at low temperatures and with minimal damage.

[Conventional technology]

Dry etching methods commonly used in the manufacturing process of semiconductor integrated circuits include plasma etching and reactive sputter etching, which are currently widely used.
In these etching methods, a reactive gas is discharged under reduced pressure to generate reactive species such as radicals and ions, which react with the surface of the substrate to be etched to perform etching.

This type of dry etching method is superior to the solution etching method in terms of processing accuracy, so it is becoming increasingly important as processing dimensions become finer and it is necessary to process patterns from 1 μm to sub-μm level. It has become a technology. However, in the plasma etching method and reactive spanter etching method, the substrate to be etched is placed inside the discharge vessel, so the substrate to be etched is easily damaged by charged particles, and the resist is damaged by thermal radiation of the plasma. There are problems such as deterioration.

A new dry etching device to solve these problems was devised by the inventors K.
It is described in Publication No. 8. The application discloses a means for generating a metastable excited species, a means for moving the metastable excited species to a reaction chamber in which a substrate to be etched is installed, and a means for introducing a process gas used for etching into the reaction chamber. An example of an apparatus is illustrated in which the substrate to be etched is etched by active species generated by a reaction between the metastable excited species and the reactive gas. With this equipment configuration, it has become possible to etch the substrate to be etched at a location away from the metastable excited species generation area (discharge area), which prevents damage to the substrate due to charged particles and damage to the resist from thermal radiation from the plasma. Low-temperature dry etching is now possible with significantly reduced deterioration. Although there are many unknowns about the reaction mechanism in such systems, when a metastable excited species collides with a process gas containing a halogen element, the excitation energy held by the metastable excited species is transferred to the process gas. However, it is thought that the etching reaction is induced by decomposing the process gas or activating the process gas.

The etching method based on the deexcitation reaction of metastable excited species has the advantage of being able to be carried out at low temperatures and with little damage from charged particles. When mixing a third gas other than the process gas,
The problem that the etching rate decreased by a large 111 gK was encountered.

Conventionally, there have been many cases in which 77jg3 of gas is mixed in to advance the desired etching reaction as described above.
Example of mixing HF5 K H rich gas (Unexamined Japanese Patent Publication No. 57-19
0320 Publication), 7 Example of mixing oxygen into Leon gas (
(Japanese Unexamined Patent Publication No. 53-29237).

However, in the dry etching method that utilizes the deexcitation reaction of metastable excited species, which is the subject of the present invention, the above-mentioned problems arise when a third gas is mixed in. This is due to the fact that energy is transferred by evenly colliding with the process gas containing the halogen element and the third gas. As a result, the utilization efficiency of the metastable excited species was significantly reduced, causing a decrease in the etching rate.

[Problem that the invention seeks to solve]

In the above-mentioned conventional method, a third etching process gas is used to advance the desired etching reaction with a process gas containing a halogen element.
The problem lies in the fact that the gas uniformly collides with the metastable excited species and induces a deexcitation reaction of the metastable excited species.

The purpose of the present invention is to solve the above-mentioned problems by reducing the deexcitation reaction caused by the collision with the metastable excited species and the reaction with a process gas containing a halogen element! It is an object of the present invention to provide an apparatus capable of preferentially performing the above-mentioned metastable excited species and greatly reducing the probability that the metastable excited species will be deactivated by the third gas.

[Means for solving problems]

The above purpose is to adjust the positions of the introduction ports of the metastable excited species, the process gas containing a halogen element, and the third gas to be introduced into the reaction chamber that accommodates the substrate to be processed, and to This is achieved by applying K so that the reaction between the species and the process gas containing the halogen element takes place preferentially.

[Effect]

As a result, the probability that the metastable excited species generated in the discharge chamber and led to the reaction chamber will collide with the third gas and be deactivated is greatly reduced, allowing them to react efficiently with the process gas containing the halogen element. , the etching reaction is promoted.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a reaction chamber, and 2 is a substrate to be processed, which is installed on a filter substrate stand 3. 4 is a storage section for gas for generating metastable excited species], and the gas flowing out from the storage section 4 is handled by a valve 5. Trout 70-
After passing through the control t-6J-, it is converted into a metastable excited species in the metastable excited species generating section 7. In this example, 2. , 45
Metastable excited species were generated using GHz microwave discharge. 8 is a microwave generation source. When nitrogen gas is stored in the gas storage section 4, metastable excited nitrogen molecules Nf(A'Σt) are generated in the metastable excited species generation section 7. Ions and electrons simultaneously generated by the microwave discharge disappear due to recombination reactions, but the metastable excited nitrogen molecules have a lifetime of 2.1 seconds, so at the stage of entering the reaction chamber 1 through the tube 9, remains in an excited state.

7. When storing the process gas containing 10ri halogen elements, depending on the purpose, C12゜SFa
, CF4, CC1a, SFg, etc. The process gas flowing out from the storage section 10 is passed through the valve 11, the mass flow controller 12, and the pipes 13 and 1.
4 and flows into the reaction chamber 1.

In the figure, 15 is a storage unit for storing the third gas, and stores Hz, 02, etc. depending on the purpose. The third gas flowing out from the storage section 15 is passed through a valve 16, a mass flow controller 17'kfj-ta (D) and a mass flow controller 17'.
9 and flows into the reaction chamber 1.

Note that 21 is an exhaust device (=1), and gases generated as a result of the etching reaction and unreacted gases are exhausted via the pipe 20.

According to the above device configuration, the metastable excited species flowing into the reaction chamber IK from f9 reacts preferentially with the process gas containing a halogen element flowing from the tubes 13 and 14, and the products generated by the reaction continue. This reacts with the gas g3 flowing in from the pipes 18 and 19, and finally the substrate 2 to be processed placed on the substrate table 3 is etched.

As shown in the figure, in this example, the introduction of the third gas'
1i18 and 19 are provided on the downstream side of the process gas introduction pipes 13 and 14 containing a halogen element, and on the upstream side of the substrate to be processed 2. However, the positions of the third gas introduction pipes 18 and 19 do not need to be between the process gas introductions f13 and 14 and the substrate 2 to be processed. For example, when using a process gas containing carbon atoms and halogen atoms (for example, Freon gas).

As a result of the reaction, carbon may be detected on the two surfaces of the substrate to be processed.Adding a small amount of oxygen is effective in suppressing carbon precipitation, but in such cases,
Inlet pipes 18 and 19 for the third gas (oxygen in this case)
The intended purpose can be achieved even if the position is slightly downstream of the position of the substrate 2 to be processed. This is the third
The third gas that has flowed into the reaction chamber 1 from the gas introduction pipes 18 and 19 is mostly removed from the pipe 20 by the exhaust system 21.
This is because some of the gas flows in the direction (gas downstream side) and diffuses into the reaction chamber 1.

In this example, a case is described in which only the process gas contains a halogen element and the third gas does not contain the halogen element, but the present invention can also be applied when the third gas is rich in a halogen element. It can be expanded based on the purpose. For example, Ctz and NF3 or C1x and CCL as reaction gases.
For a system that both contains a norogen element as in 4, the process gas is introduced with the gas that you want to react preferentially with the metastable excited species. All you have to do is store it.

The present invention uses a deexcitation reaction of metastable excited species with a long lifetime to dry-etch a substrate to be processed at a low temperature and with little damage, and has recently attracted attention as a technology for dry etching at a low temperature and with little damage. One of them is the photo-excited etching method. In addition to the device configuration described in the embodiment of the present invention,
Extending the light irradiation to an apparatus equipped with a light source for exciting the reprocessing gas and/or the substrate to be processed and a light introduction window for introducing the light from the light source into the reaction chamber. The etching efficiency can be increased by the mutual effect of the deexcitation reaction and the photoinduced reaction.

Note that the amount of charged particles such as ions generated during the discharge rapidly decreases as they move away from the discharge section (metastable excited species generation section) as the recombination reaction progresses. In order to reliably suppress this, it is recommended to install an ion collector just before the reaction chamber.

It goes without saying that the method of heating the substrate, which is often used in semiconductor processes, is also effective in the present invention, and the etching rate can be increased by introducing a heating means. It is also effective to provide the substrate mounting table with a rotating mechanism in order to uniformly etch the substrate.

〔Effect of the invention〕

According to the present invention, when the metastable excited species generated in the metastable excited species generating section is introduced into the reaction 34, it preferentially reacts with the process gas containing the halogen element, so that it is less likely to collide with the third gas. The rate of deactivation is significantly reduced, and as a result, the etching efficiency of the substrate to be processed is improved.

[Brief explanation of drawings]

The first factor is an apparatus configuration diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Reaction chamber, 2... Substrate to be processed, 3... Substrate stand, 4°10.15... Gas storage section, 6,12.17.
... Mass flow controller, 7... Metastable excited species generation section. 8... Power source, 9.20... Tube, 13.14... Process gas introduction tube, 18.19... Third gas introduction tube. 21... Exhaust device. Figure l

Claims (1)

[Scope of Claims] 1. A reaction chamber containing a substrate to be processed, means for generating a metastable excited species, means for introducing the generated metastable excited species into the reaction chamber, and containing a halogen element. means for introducing a process gas into the reaction chamber; and means for introducing a third gas into the reaction chamber to advance a desired etching reaction, the process gas being brought into contact with the metastable excited species; A dry etching apparatus characterized in that an inlet for the third gas is provided downstream of a spatial region where the third gas is introduced. 2. A patent claim characterized in that the third gas inlet is provided between a spatial region where the metastable excited species and the process gas come into contact and a spatial region where the substrate to be processed is installed. The dry etching apparatus according to item 1.