JPS6292324A - Dry etching method - Google Patents

Abstract

PURPOSE:To conduct dry etching giving no damage by introducing two kinds or more of reactive gases in response to materials into a vessel, introducing a deposit gas and irradiating the surface of a body to be processed by beams from the vertical direction. CONSTITUTION:A sample base 13 on which a base body to be processed 12 is placed is installed into a vacuum vessel 11. Two kinds of reactive gases containing F and Cl are introduced to another end of a discharge tube 15. A deposit gas is introduced from a gas introducing port 19. At least one of the reactive gases is excited and active species are formed while the surface of the base body to be processed 12 is irradiated by beams 21 from a light source 20. Consequently, the base body to be processed 12 is etched. Accordingly, dry etching giving no damage is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dry etching method incorporated in a process for manufacturing conductor elements, and in particular to a dry etching method for anisotropically etching LSI materials using light. Regarding.

[Technical background of the invention and its problems]

Conventionally, dry etching techniques using charged particles, typified by reactive ion etching, have been mainly used as microfabrication methods in semiconductor device manufacturing processes.

However, in semiconductor devices, it has now been discovered that the incidence of charged particles on a substrate to be processed has an adverse effect on device characteristics, and problems in processes using charged particles have become clear. In other words, it has become clear that the incidence of charged particles damages the substrate to be processed.

Photoexcited etching has been proposed as one method for eliminating damage caused by charged particles. In this case, the method of supplying only the etching species to the substrate to be processed cannot perform accurate microfabrication because the etching progresses uniformly. Therefore, directional etching using optical excitation has been proposed, in which an etching species and an oil deposit are simultaneously supplied to a substrate to be processed, and the substrate to be processed is directly irradiated with light.

This principle will be briefly explained with reference to FIG.

The body to be treated is a base material [31
An object to be etched 32 is formed thereon, and an etching mask 33 is further formed thereon.

An etching species and a deposition species are supplied to the substrate to be processed, and light is irradiated perpendicularly to the processing surface of the substrate. Then, as shown in FIG. 3(b) K, deposition occurs on the entire surface of the object to be etched 32, but the deposition 1 [
34 is removed and etching progresses, and on the side wall where no light is irradiated, the deposited R34 rays are not removed and the material to be etched is protected from attack by active species. Therefore, it is possible to perform straight etching without undercuts.

In principle, directional etching can be achieved by the method described above, but the selection of reactive gas and deposition gas depends on the substrate to be processed, as described below. For example, in the case of etching P (phosphorus)-doped polycrystalline St, C is used as the reactive gas.
J! Directional etching is achieved by using M Ni A as the deposition gas. This is because 01 and MM react to form a polymer, which adheres to the side wall and prevents undercuts.At the same time, this deposited film is removed on the light irradiated surface, and C1w, child and 81 react. This is because etching progresses in the direction of light irradiation. but.

When the material is single crystal S1, etching with C1-based active species is extremely slow, making it impossible to obtain a practical etching rate.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks and solves the above-mentioned drawbacks and solves the problem of single-crystal Si-? Thin Si
Impurity-doped polycrystalline S on oxide film! Cattle conductor materials such as PC, AJ,? Various materials such as metals such as Jo and their silicide compounds, and insulators such as sto, -q can be etched directionally without damage by freely selecting reactive gases and deposition gases. An object of the present invention is to provide a photoexcited dry etching method which is suitable for manufacturing semiconductor devices.

[Summary of the invention]

The gist of the present invention is to use a plurality of reactive gases and a deposition gas for directional etching of semiconductor device manufacturing materials.

That is, the present invention provides a dry etching method for etching an object to be processed housed in a vacuum container, in which at least two or more reactive gases are introduced into the container depending on the material, and a deposited film is further generated. This is a damage-free dry etching method in which a deposition gas is introduced for etching, and at the same time, light is irradiated onto the surface of the object to be processed from the vertical direction while anisotropic etching is performed in the direction of the light irradiation.

The outline of the present invention will be explained by taking etching of a single crystal S1 as an example. In the case of the single crystal 81, it is known that the etching rate with 02-based active species is generally slow, and the etching rate r with F-based active species is fast. In this method, which performs anisotropic etching while forming a film, it is important to form a pattern. For example, acrylic and methacrylic organic compound gases react with Cj-based active species and Deposits occur on surfaces. It does not react with F-based active species to cause deposition. Therefore, when etching single-crystal SIt using this method, in order to form a film, an ``''-based active species and an acrylic or methacrylic gas are supplied, and the portion of the light irradiated area where the film has been removed is etched. Therefore, it is necessary to simultaneously supply F-based active species.We have found that by appropriately adjusting these gases, film formation and etching can occur simultaneously and anisotropic etching can be achieved.

Next, we will explain the etching of 1 person z as an example.

In the case of a person, etching cannot be performed using Cj-based active species alone, but etching can be carried out by supplying active species excited by BCj with a discharge tube and irradiating with light. This means that the removal of the oxide film of Aj formed on the surface of the person 10 is C
This is because only one type of active species does not cause etching.

Etching progresses rapidly using only C1-based active species when the oxide film on the surface has been removed, but etching progresses uniformly when the surface oxide film is removed. That is, in order to perform directional etching, it is necessary to separately add a deposition gas and perform etching based on the principle shown in FIG.

That is, by using a reactive gas containing two or more types of halogen as a deposition gas as described above, it is possible to etch materials that cannot be etched with one type of reactive gas. By using a deposition gas, directional etching can be performed.

〔Effect of the invention〕

According to the present invention, directional etching can be performed without damaging various materials used in the manufacture of semiconductor devices. For various materials, optimal directional etching can be performed for each material by selecting a reactive gas and a deposition gas.

Furthermore, by using two or more types of reactive gases, an improvement can be achieved compared to etching with one type of reactive gas.

Examples of these include improved X-ray etching speed, uniformity of etching over a large area, etc.

Because of these K, the present method has a great impact on the ultra-LBI fabrication process.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained using illustrated embodiments.

FIG. 1 is a beak construction diagram showing an example of a dry etching apparatus for carrying out the present invention. In the figure, reference numeral 11 denotes a vacuum container, and a sample stage 13 on which a substrate 12 to be processed is placed is installed inside the container 11. A gas inlet 14 is provided in the container 11, and one end of a discharge tube 15 is connected to this gas inlet 14. A waveguide 171C is coupled to the discharge tube 15 and connected to the microwave power source 16. Two types of reactive gases (for example, NF and Cj) containing each of F and C1 are introduced into the other end of the discharge tube 15.Furthermore, the gas in the container 11 is introduced through a gas exhaust port. It is designed to be exhausted from 18. Also,
A deposition gas (for example, MMA) is introduced from the gas inlet 19.
Light 21 from a light source 20 passes through a window 22 provided in the vacuum container and is introduced into the interior and irradiated thereon.

Next, using the apparatus shown in
', and using KrF laser light as a light source. The results are shown for the amount of . The etching rate is the etching rate in the light irradiated area, and the deposition rate is the deposition rate in the non-light irradiated area. In the figure, film formation, □, and etching occur simultaneously in the gas mixture ratio region of region A, indicated by dotted dots. It has been confirmed that etching is achieved.

In order to obtain good anisotropic etching as shown in this figure, it is necessary to adjust the gas mixture ratio to an appropriate region where etching and deposition occur.

In addition to NF, CF4. C,F,
.

C-P compound gas such as C, F, or 0 with them
．． , Mixed gas with N, t or Xe F, ,
8F'@.

Other gases may be used as long as they contain F, such as 5iP4, and generate F-based active groups upon excitation. Similarly, if the CL-based reactive gas generates Ct-based active species upon excitation, then
(Not limited to j, other gases may be used.

FIG. 4 shows an apparatus useful in another embodiment of the invention. Note that the same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

The difference between this device and the one shown in Figure @1 is the F thread gas inlet and the Ct
The system gas inlet is different, that is, the Ct-based gas is introduced into the vacuum vessel from the gas inlet 41 without discharging, and the F
This method discharges only the system gas. In this case, what is generated by the excitation is F-based active species, but this active species excites Ct and gas introduced into the vacuum vessel to generate Ct-based active species. Accordingly, [using the apparatus shown in Figure 4, NF,
is discharged, Ctt is introduced from 41, and M M A is 1.
9, the same results as when using the apparatus shown in FIG. 1 were obtained.

FIG. 5 shows another embodiment of the invention. In this method, the substrate to be processed is irradiated with an electron beam 51 to excite the reactive gas. In a similar manner, the substrate to be processed may be irradiated with light absorbed by at least one of the reactive gases in parallel instead of the beam. If the substrate is irradiated vertically, directional etching can be performed. The same light may be used if the light 21 to remove the light is absorbed by the reactive gas, but for sRJ where the light 21 is not absorbed by the reactive gas, a different wavelength source from another light source may be used. Also good.

FIG. 6 shows an apparatus used in another embodiment of the invention. The same parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

This device differs from the dotted line in Figure 1 in that, instead of introducing the deposition gas into the vacuum chamber without exciting it, the deposition gas is excited by microwave discharge in the same way as the reactive gas, and the active species generated there are pumped into the vacuum chamber. It is intended to be introduced into the content. That is, 61
A microwave discharge tube 63 is coupled to a quartz tube 62 connected to a deposition gas inlet of 1, which is connected to a microwave power source 64. In the case of mixed gases such as these gases and oxygen, and other elements, deposition tends to occur if these gases are excited in advance by electric discharge or the like. Some gases do not deposit unless they are excited, and when these gases are used as a deposition gas, a device like the one shown in Figure #I6 is required.

Nine, in addition to electric discharge, light and heat can be used as excitation means.

There are electron beam irradiation and the like, and any of them may be used.

Furthermore, when deposition occurs, the temperature of the substrate to be treated affects the amount of deposition. Further, lowering the temperature of the substrate to be processed also has the effect of facilitating deposition. To improve process reproducibility, rounding can be done by keeping the substrate temperature constant.
Furthermore, in order to deposit effectively, it is desirable to cool the substrate to be processed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for carrying out the invention, FIG.
Using the apparatus shown in Figure 1 of Zusha, NF, +Ct. Characteristic diagram showing the results of measuring the etching rate and deposition rate when changing NFafii & when etching single crystal S1 with a mixed gas of +MMA, @3
The figure is an explanatory diagram showing the principle of anisotropic etching in the present invention, Figure 4 is a block diagram of an apparatus for carrying out another embodiment of the present invention, and Figure 5 is another example of the present invention. FIG. 86 is a configuration diagram showing an apparatus used in another embodiment of the present invention. Agent Patent attorney Yudo Nori Chika Takehana Kikuo NFB Sono (other meaning) Figure 2 Figure 3 Figure 4 Figure 5 Procedural amendment (method) 1985 Chi 2.1 Tsun

Claims (10)

[Claims] (1) At least two reactive gases containing a halogen element and a thin film deposition gas are introduced into a container in which a substrate to be processed is housed, and at least one of the reactive gases is excited to generate active species. A dry etching method characterized in that the substrate to be processed is etched by irradiating the substrate to be processed with light. (2) The method according to claim 1, characterized in that, as the means for exciting the reactive gas to generate active species, these active species are generated in a region separated from the inside of the container. Dry etching method. (3) The method according to claim 1 or 2, characterized in that electric discharge, electron beam irradiation, light irradiation, or heat is used as means for exciting the reactive gas to generate active species.
Dry etching method described in section. (4) The means for exciting the reactive gas to generate active species includes irradiating an electron beam parallel to the object to be processed in the container, or generating reactive species absorbed by at least one of the reactive gases. Direct the gas excitation light perpendicularly to the substrate to be processed.
Alternatively, the dry etching method according to claim 1, characterized in that the irradiation is performed in parallel. (5) The dry etching method according to claim 4, wherein the wavelength of the light irradiated onto the substrate to be processed is different from or the same wavelength as the wavelength of the light for excitation of the reactive gas. (6) The thin film deposition gas is an organic gas such as acrylic or methacrylic gas, and is introduced into the container in the form of raw gas.
Dry etching method described in section. (7) The thin film deposition gas is an inorganic gas such as silane, or a mixed gas of these gases and oxygen, nitrogen, etc., and must be excited in advance in a region different from the reactive gas. A dry etching method according to any one of claims 1 to 3. (8) The dry etching method according to any one of claims 1 to 7, wherein at least one of the active species is a fluorine atom. (9) The dry etching method according to any one of claims 1 to 8, wherein the substrate to be processed is cooled. (10) Claims 1, 2, 3, and 6, wherein the reactive gas is NF_2, Cl_2, and the deposition gas is methyl methacrylate. , the dry etching method described in Items 8 and 9.