JPS61161722A - Photoexcitation etching method and etching apparatus - Google Patents

Abstract

PURPOSE:To enable a fine pattern to be formed in a photoexcitation etching process, by arranging a source for depositing a thin film within a container so that the deposit particles are emitted into a gas phase for depositing the thin film on the substrate simultaneously with etching the substrate. CONSTITUTION:A stage 13 for carrying a substrate 12 to be treated is housed within a vacuum container 11. The container 11 is provided with gas inlet 14 and a gas outlet 15. The top wall of the container is provided with a window having a transparent plate 16, over which an ArF excimer laser as a light source 17 is arranged. A container 21 for receiving photoresist 22 as a deposit source is arranged over a stage 13 within the container 11. A heater 23 is provided below the container 21 for heating the deposit source 22 in the container 21. The heater 23 is adapted to heat the deposit source 22 simultaneously with the irradiation from the light source 17 so as to evaporate the deposit source 22, causing the deposit particles to be emitted in a gas phase.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a photoexcitation etching method and an etching apparatus used in the manufacture of semiconductor devices.

[Technical background of the invention and its problems]

Conventionally, in the etching process of fine patterns in the manufacture of semiconductor devices, reactive ion etching has been widely used to achieve etching anisotropy.

However, the reactive ion etching method poses a problem of damage caused by the incidence of high-energy ions on the surface of the substrate to be processed.

Therefore, recently, a photoexcitation etching method has been proposed as an etching technique that does not involve irradiation with high-energy ions and does not damage the substrate surface. This is a method in which a gas in a gas phase or the surface of a substrate to be processed is excited by light, and the substrate is etched by excited particles, and is attracting attention as a damage-free etching technique.

However, this type of method has the following problems. That is, in the method of etching by exciting gas in the gas phase, it is difficult to give directionality to the generated excited particles, and a so-called undercut phenomenon occurs in which etching progresses to the bottom of the mask material. . For this reason, it has been difficult to form a fine pattern that is faithful to the mask pattern.

[Purpose of the invention]

The object of the present invention is to be able to perform etching without causing damage to the substrate to be processed by ion irradiation, etc., to achieve an anisotropic etched shape without undercuts, and to be useful in forming fine patterns. An object of the present invention is to provide a photo-excited etching method.

Another object of the present invention is to provide a photoexcited etching apparatus for carrying out the above method.

(Summary of the Invention) The gist of the present invention is to perform etching by optical excitation while forming a thin film on the surface of a substrate to be processed. By preventing this, etching under the mask material can be suppressed.

Here, when forming '7IJIll, a thin film is also attached to the horizontal portion of the surface of the substrate to be processed, but this is etched or removed by light incident perpendicularly to the surface of the substrate to be processed. For this reason, the surface of the substrate to be processed is always exposed in the area irradiated with the perpendicularly incident light, and etching progresses by reacting with the excited particles. On the other hand, the thin film attached to the part perpendicular to the surface of the substrate to be processed is not etched because no light is incident thereon, and thus protects the side wall from attack by excited particles.

The thin film deposition source must be such that the deposited thin film can be removed at a high rate in the light irradiated area by vertical incidence of light on the substrate to be processed in the etching reaction gas atmosphere. In addition, the parts that are not irradiated with light must be resistant to reactions against excited particles. from the deposition source into the gas phase of the sediment.

The emission of this substance involves heating the deposition source, irradiation with light, etc., and it is necessary to be able to control the amount of emission.

The present invention focuses on these points, and introduces a reactive gas that is activated by photoexcitation into a container containing a substrate to be processed.
In this photo-excited etching method in which the substrate to be processed is etched by irradiating light in the gas and onto the substrate, a thin film deposition source is installed in the container, deposited particles are discharged from the deposition source into the gas phase, and the This is a method in which a thin film is deposited on a substrate and the substrate is etched at the same time.

The present invention also provides an apparatus for carrying out the above method, including a container for accommodating a substrate to be processed, a means for introducing a reactive gas activated by photoexcitation into the container, and a means for evacuating the gas in the container. means for irradiating the gas and the substrate with light; and a thin film deposition source disposed within the container for releasing deposited particles into the gas phase during etching of the substrate.

〔Effect of the invention〕

According to the present invention, since the etching is performed by photoexcitation, there is no crystalline damage to the substrate to be processed.
The substrate can be etched. Moreover, by etching while forming a thin film, it is possible to avoid the phenomenon of isotropic etching or progress of etching below the mask material in conventional photoexcitation etching, and achieve anisotropic etching. . Therefore, it is extremely effective in forming fine patterns. Furthermore, since etching isotropic and undercuts can be avoided, there are advantages such as improved freedom in material selection.

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

FIG. 1 is a sectional view showing a schematic configuration of a photoexcitation etching apparatus according to an embodiment of the present invention. In the figure, 11 is a vacuum container, and a substrate 12 to be processed is placed inside this container 11! It
A stage 13 is housed therein.

The container 11 is provided with a gas inlet 14 and a gas exhaust port 15, respectively. Then, CQ2 gas, for example, is introduced into the container 11 as a reactive gas from the gas inlet 14, and the gas introduced into the container 11 is transferred to the gas exhaust port 1.
It is designed to be exhausted through 5. Here, the reactive gas is a gas that is activated by light irradiation.

On the other hand, a window is provided in the clay wall of the container 11, and a transparent plate 16 is attached to close this window. transparent plate 1
A light source 17 made of, for example, an ArF excimer laser oscillator is disposed above the light source 6 . The light from the light source 17 is introduced into the container 11 through the transparent plate 16 as parallel light, and is irradiated onto the substrate 12 to be processed.゛The configuration up to this point is the same as the conventional device,
The present embodiment differs from the above in that a source of agglomeration and a heater are provided inside the container 11. That is, at a position above the stage 13 in the container 11, for example, a photoresist 22 (22s) is placed as a deposition source.

Container 21 (21r) for containing 222).

212) is provided. Here, the container 21 has an optical path P
-P' and is illuminated by light from the light source 17. Since the container 21 and the deposition source 22 are in the optical path, the optical path width becomes narrow from P-P' to Q-Q', but the deposition source does not cast a shadow on the substrate 12 to be processed.
Uniform light is irradiated. Also, container 2
A heater 23 (231, 232>) for heating the deposition source 22 in the container 21 is provided at the bottom of the container 21.The heater 23 heats the deposition source 22 together with the light irradiation from the light source 17. , the deposited particles 8122 are evaporated and the deposited particles are released into the gas phase.

Note that the J deposition source 22 is preferably set at a position where one film is deposited uniformly on the surface of the substrate 12 to be processed. In the example shown in FIG. 1, it is installed perpendicular to the light, but it may also be tilted inward. In addition, deposition source 2
The number of units 2 installed is not limited to two and can be changed as appropriate, and may also be installed in an annular shape coaxially with the substrate 12 to be processed. Further, the deposition source 22 is connected to the substrate 1 to be processed.
2 can be installed on the same plane as the base 12 or below it.

Next, a method of etching the N4'' poly 3i using the above-mentioned apparatus will be explained.

First, chlorine (Ca2) gas was used as the introduced gas, and photoresist was used as the deposition source 22. In addition, the light source 17
An ArF excimer laser oscillator was used. Here, the light from the light source 17 must be such that -7 photoresist is evaporated by the irradiation with the light. Additionally, this light must generate chlorine radicals. Excimer laser light evaporates photoresist and also generates chlorine radicals, thus meeting the above requirements.

Note that light from a mercury lamp that emits ultraviolet light that generates many chlorine radicals may be used, but in this case, the evaporation rate of the photoresist is slow, so it is effective to use light mixed with ArF excimer laser light. be.

Under these conditions, etching was carried out as shown in FIGS. 2(a) to 2(C). That is, as shown in FIG. 2(a) as the substrate 12, N + A poly-Si film (to be etched) 32 is deposited, and 5i
A mask on which an Oz mask 33 was formed was used. This substrate 12 to be processed was placed on the stage 13 and etched by optical excitation. During the etching process, as shown in Figure 2 (
As schematically shown in b), the book 1l by deposit #i22
I34 adheres to the entire surface. Here, did it adhere to the surface of the poly-3i film 32 in the horizontal direction? 11I34 is removed by vertically incident light. On the other hand, the S film 34 attached to the etched sidewall of the polygon 5i 1132 remains because no light is incident thereon. For this reason, etching proceeds while leaving the film 34 on the side wall. As a result, an anisotropic etching shape with no undercut below the mask 33 was achieved as shown in FIG. 2(C). Note that the thickness of the thin film attached to the etching sidewall is extremely thin, and changes in pattern dimensions due to this thin film 34 hardly pose a problem.

Thus, according to this embodiment, by performing etching while depositing a thin film 1134 on the surface of the substrate 120 to be processed using the deposition [22], it is possible to prevent the etching from proceeding below the mask 33, and to remove the poly-Si film. 32 can be anisotropically etched. Moreover, since etching is performed by photoexcitation, there is no damage caused by ion irradiation or the like.

Therefore, it is extremely effective in forming fine patterns, and exhibits great effects in manufacturing semiconductor devices. In addition, by simply adding the deposition source 22, heater 23, etc. to the conventional device,
It also has advantages such as being easily realized.

Note that the present invention is not limited to the embodiments described above. For example, as a means (evaporation means) for releasing the deposited particles from the deposition source, it is not necessarily necessary to use both light irradiation and heating with a heater, and only heating with a heater may be used. Furthermore, if the amount of light irradiation is sufficient to evaporate the deposition source, the heater may be omitted. The irradiation of light onto the substrate to be processed and the irradiation of light onto the deposition source may be performed using independent light sources. Further, the deposition source is not limited to photoresist, and any thin film produced by the deposition source may be removed by irradiation with etching light. For example, various vinyl polymers,
Polymer materials such as fluorocarbon polymers and c-cI2 polymers, or materials that adhere to the substrate to be treated to form a thin film among these materials may also be used. In addition to polymer materials and their monomers, vapor deposition of atoms such as metals may be used as long as the etching rate of the thin film thereof is high.

Further, the mask does not necessarily need to be formed directly on the surface of the object to be etched, and may be located at a position apart from the surface. Furthermore, it is also possible to omit the mask by selectively irradiating the portion to be etched with light from a light source. Further, the type of reactive gas introduced into the container can be changed as appropriate depending on the material to be etched. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a photoexcitation etching apparatus according to an embodiment of the present invention, and FIGS. 2(a) to (C) are cross-sectional views showing the etching process of N+ poly-Si using the above-mentioned apparatus. be. 11... Vacuum container, 12... Substrate to be processed, 13...
- Stage, 14... Gas inlet, 15... Gas exhaust port, 16... Transparent plate, 17... Light source, 21...
Container, 22... Deposition source, 23... Heater, 31...
・5i02 substrate, 32...N+poly-Si, 33...
SiO2 mask, 34...thin film. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] (1) Photoexcitation etching in which a reactive gas that is activated by photoexcitation is introduced into a container containing a substrate to be processed, and the substrate is etched by irradiating light into the gas and onto the substrate to be processed. In the method, a thin film deposition source is installed in the container;
A photo-excited etching method characterized by emitting deposited particles from the deposition source into a gas phase to deposit a thin film on the substrate and etching the substrate at the same time. (2) The photoexcitation etching method according to claim 1, wherein the substrate to be processed is a substrate on which an etching mask is selectively formed. (3) The photo-excited etching method according to claim 1, characterized in that the means for releasing the deposited particles from the deposition source includes irradiating the deposition source with light or heating the deposition source with a heater. (4) The photoexcited etching method according to claim 1, wherein the means for irradiating the substrate with light is irradiating light perpendicularly to the surface of the substrate. (5) A container for accommodating a substrate to be processed, a means for introducing a reactive gas activated by photoexcitation into the container, a means for exhausting the gas in the container, and irradiating the gas and the substrate with light. A photoexcited etching apparatus comprising: a light source; and a thin film deposition source installed in the container and releasing deposited particles into a gas phase during etching of the substrate. (6) The optically excited etching apparatus according to claim 5, wherein the substrate to be processed has an etching mask on its upper surface. (7) The photo-excited etching apparatus according to claim 5, wherein the deposition source emits the deposited particles by light irradiation or heating by a heater. (9) The photoexcitation etching apparatus according to claim 5, wherein the light source irradiates light perpendicularly to the surface of the substrate to be processed.