JPS59181538A - Dry-etching apparatus - Google Patents

Abstract

PURPOSE:To reduce the loss of ultraviolet rays or X-rays and obtain a high etching speed by a method wherein a mask is provided as a light window of a reaction vessel and the etched material is placed facing the mask closely. CONSTITUTION:A mask 27 is fixed on a wall of a vessel 15. The mask 27 is composed of a substrate 28 made of the material transmitting ultraviolet rays, such as quartz, and a mask pattern 29 formed on the substrate 28 and reflects or absorbs ultraviolet rays. Ultraviolet rays emitted from an Hg-Xe lamp light source 30 are reflected by a mirror 31 and transmitted through a lens 32 and the mask 27 and introduced into the reaction vessel 15. This shadow pattern is transferred to a silicon wafer 16 loaded on a wafer loading table 17 which facilitates X-Y scanning. An X-Y scanning driving mechanism 20 permits required positions of the wafer to be irradiated by ultraviolet rays successively. For instance, chlorine gas is introduced through an introducing pipe 22 and exhausted through an exhaust pipe 24 maintaining the pressure in the reaction vessel 15 approximately 100Torr so that a mask pattern can be formed on the etched material 16 without using a mask.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a dry etching apparatus for selective etching using ultraviolet light or X-rays.

[Prior art and its problems]

Plasma etching technology is indispensable for microfabrication of semiconductor integrated circuits, which are becoming increasingly finer in recent years, and reactive ion etching (RIE) has become mainstream as one of these techniques. However, this type of method exposes the material to be etched to plasma, which causes various types of radiation damage, which causes many problems when the device is fabricated into a very large scale integrated circuit (LSI). Therefore, a damage-free etching technique is desperately needed, and one of them is a method in which active species of a reactive gas are generated by light irradiation, and the surface of the material to be etched is excited and etched. Since this method uses ultraviolet light or X-rays, there is no loss due to charged particles, and it is also selective due to the fact that the surface of the etching material will not be etched unless it is excited by ultraviolet light or X-rays. There is no need for a mask such as a resist that is formed in close contact with the material to be etched by irradiating ultraviolet rays or This is a problem in practical application.The reason for this is that light absorption by lenses, filters, etc. in the light introduction system and light absorption by the reactive gas may cause the light to reach near the surface of the material to be etched, which is necessary for actual etching. There is a fact that the amount of ultraviolet light or X-rays becomes extremely low.This will be explained below based on experimental data.

FIG. 2 shows the spectrum of light from an Hg Xe lamp as an example of a light source. The horizontal axis is the wavelength of light, and the vertical axis is its intensity. It can be seen that the intensity of light passing through a fused silica plate with the same thickness as the conventional introduction window, shown as a △, is significantly reduced in the ultraviolet region, compared to the direct light from the lamp shown with ○. . If chlorine gold is used as the etching gas, light with a wavelength of 280 to 400 nm is required for dissociation, so the absorption of light in the light introduction system is reduced to l' of chlorine radicals, significantly reducing the etching rate. .

Figure 3 shows the measurement of the light from an Hg-Xe rung that has passed through a chlorine atmosphere 50 times against the pressure of chlorine.
Especially the intensity change is 30・2.313.365n
The figure shows the light of m. Light of other wavelengths showed less change than these. This graph is 100 Torr k
Approximately 90% of the light is absorbed as the light travels through the 1L element, and the amount of light that actually contributes to etching decreases significantly near the material to be etched. Due to these facts, it has been found that the conventional apparatus cannot achieve a practically sufficient etching rate.

FIG. 4 shows a configuration diagram of a conventional device. Light from the Hg-Xe lamp light source (1) passes through a lens (2), a light introduction window (3), and then a mask (5) in a reactive gas (4) atmosphere.
The material to be etched (6) placed opposite the mask (5) is irradiated.

Here, the light introduction window (3) has no optical effect and is simply provided as a vacuum hole, and the reactive gas atmosphere (4) from the light introduction window (3) to the mask (5) does not contribute at all to etching. I haven't. As shown in the experimental data, these factors are responsible for the etching speed. Further, since the mask (5) was placed in a reactive gas, etching of the mask (turn (7) itself) and adhesion of etching products occurred, resulting in severe deterioration of the mask.

[Purpose of the invention]

The present invention improves the drawbacks of the conventional methods mentioned above, and is a dry etching device that can perform selective etching without resisting, has little irradiation damage, and has a high etching speed. It is about providing.

[Summary of the invention]

In the present invention, ultraviolet light or X-rays are passed through the mask, the mask pattern is projected onto the material to be etched in a reactive gas atmosphere, and the pattern is created directly on the surface of the etching material without creating an etching mask with resist or the like. In the etching apparatus, the mask is installed as a light introduction window in the reaction vessel, and the material to be etched is placed close to and facing the mask, thereby reducing the loss of ultraviolet light or X-rays and achieving a high etching rate. .

〔Effect of the invention〕.

According to the present invention, irradiation of 1μ scratches without using plasma.

Dry etching with little resist stress is now possible at high etching speed.

[Embodiments of the invention]

FIG. 5 is a room layout diagram for fully explaining one embodiment of the present invention. In the figure, a mounting table (17) on which a destructive etching material (16) is placed is provided inside the reaction vessel (15), and this mounting table (17) has a shaft supported by a bearing (18). (19) through the X-Y scanning drive mechanism (
20) makes it movable. In addition, the reaction vessel (1
5) is connected to an inlet pipe (22) for introducing the reactive gas (21) through a mass flow meter (233), and is connected to a cryobong (25) at low vacuum through an exhaust pipe (24). Rotary bong (26
) is connected to enable exhaust.

A mask (27) is fixedly arranged on the wall of the container (15).

This mask (27) has a substrate (28) made of fused silica or the like that transmits ultraviolet rays, and a mask pattern (29) formed on the surface of the substrate made of gold such as Cr or AL that totally reflects or absorbs ultraviolet rays. It consists of power. Further containers (15
) A tIg-Xe lamp light source (30) is fixedly placed outside the light source (30), and the ultraviolet light emitted from this light source (30) is reflected by the FD mirror (31), becomes parallel light from the lens (32), and is transmitted to the mask (27). ) and selectively passes through the mask (27). 1. The re-passed ultraviolet light is applied to the material to be etched (16) on the mounting table (17) which is placed close to and opposite to the material to be etched.
is irradiated. This device is a step-and-repeat system and operates as follows. Namely.

The ultraviolet light emitted from the Hg-Xe lamp light/M (30) is reflected by the mirror (31), passes through the lens (32), passes through the mask (27), and is guided into the reaction vessel (15). This shadow pattern is an X-Y scan! , silicon wafers (1) on 14 machines (17)
16).

The X-Y scanning drive/movement mechanism (20) is a moving mechanism for sequentially irradiating all desired locations of the sea urchin with ultraviolet rays. Introductory tube (
For example, chlorine gas is introduced from the reaction vessel (15).
) while reducing the total pressure in the exhaust pipe (
By evacuating air from 24), a mask pattern can be formed on the etching material (16) made of silicon without using the entire length.

In this apparatus, a mask (27) and a material to be etched (
It has become clear from experiments that the distance 16) must be within the range shown by diagonal lines in FIG. 1, relative to the reactive gas pressure, in order to obtain a practical etching rate.

FIG. 6 shows the etching rate measured against the pressure of chlorine gas introduced into the reaction vessel when phosphorus-added polycrystalline silicon was completely etched using a 200 W Hg-Xe Lang gold in the above-mentioned apparatus.

Graph A is data obtained by the system improved by the present invention, and graph B is data obtained by a conventional device. The etching speed 1f has been improved from 5 to 150 Torr, especially at 20Torr.
The etching speed is greatly improved and the chlorine pressure is higher than rr. A high-speed etching device can be obtained by increasing the
do.

Furthermore, since the mask pattern is placed outside the reaction vessel, there is virtually no time limit to the life of the mask.

[Other embodiments of the invention]

FIG. 7 shows another embodiment of the present invention. Although the present invention reduces the loss of light due to the light introduction window and the reactive gas and improves the etching speed, the actual example shown in FIG. It is intended to reduce the loss of light. In an experiment to investigate the absorption of light in a reactive gas that resulted in Figure 3 shown above, all air at atmospheric pressure was introduced and measurements were taken. I didn't see it. Therefore, in order to reduce the loss of light in the air, the distance between the lens and the mask is X-axis. In Figure 7) 1g
-,,The light from the Xe lamp light source (36) is made into parallel light beams by the lens (37) just before it, and the light from the mask (38) (
[- passing through and selectively irradiating the abrasive etching material (39);

Here, the space between the lens (37) and the mask (38) is evacuated through the evacuation pipe, and there is no loss of light in this area. In addition, since the lens (37) is used for vacuum sealing, there is no need for a new light introduction window to keep the light introduction chamber (40) in a vacuum, and this embodiment reduces light loss as much as possible. As shown in FIG. 5, an improvement of several orders of magnitude in etching speed was observed.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the relationship between the distance between the mask and the material to be etched and the gas pressure for high-speed etching, and Fig. 2 is a characteristic diagram showing the relationship between the distance between the mask and the material to be etched and the gas pressure. Figure 3 is a temporal diagram showing the spectral distribution. Figure 3 is a characteristic diagram showing the relationship between chlorine pressure and light intensity. Figure 4 is the configuration of the conventional device. FIG. 5 is a layout diagram for explaining one embodiment of the present invention, and FIG. 6 is a diagram showing the chlorine pressure and etching rate of phosphorus-added polycrystalline silicon in the apparatus of one embodiment of the present invention. FIG. 7 is a layout diagram showing the structure of another embodiment of the present invention. l ・LIg-Xe lamp light source, 2...lens. 3...Light introduction window, 4...Reactive gas, 5...Mask. (3. Material to be etched, 7. Mask pattern. 8. Mounting table, 9. 1 Drive shaft, 10. Drive mechanism. 11. Reactive gas introduction pipe, 12. Reaction vessel. 13. Exhaust pipe, 14. Drive shaft bearing, 15 Reaction vessel. 16 Material to be etched, 17-Ri'tlit
The stand. 18. Drive shaft bearing, 19. Drive shaft, 20... Drive mechanism. 21 reactive gas, 22 gas introduction pipe. 23.-mass flow meter, 24...exhaust v. 25 ・CRYO pump exhaust system. 26...Rotary bong exhaust system, 27...Mask. 28 - Mask substrate, 29 - Mask pattern. 30-Hg-Xe lamp, 31-mirror, 32...lens. 33...Diaphragm vacuum gauge, 34...0 ring. 35...Gate valve, 36...Hg Xe lamp. , U7... Lens, 38 - Mask, 39... Material to be etched. 40... Light introduction chamber, 41... Drive shaft bearing, 42...
, drive mechanism. 43... Drive shaft, 44... Mounting table, 45... Empty gauge on diaphragm. 46.Reactive gas introduction resistance, 47. Exhaust pipe. 48...Exhaust pipe. (7317) Patent Attorney Noriyuki Chika (and 1 other person) Fig. 1: 61 尤子 (m 瓜) Fig. 2: Uko-ahi (ntm) Fig. 3: The Five Keys (Torr) 4 Figure 5 middle hepa Figure 6 1 drift,! 7) Goka (7o toto)

Claims (4)

[Claims] (1) A reaction vessel into which a reactive gas is introduced and exhausted;
! a movable @ mounting table, a means for driving the mounting table, a mask having an ultraviolet light or viX-ray transmitting part and a non-transmissive part, and an ultraviolet light or irradiation means for irradiating the etching material with X-rays, the mask serves as an introduction window for ultraviolet light or UV rays in the reaction vessel, and the material to be etched is They are placed close to each other and face each other with the reactive gas interposed therebetween, and the opposing distance is set within the range shown by diagonal lines in FIG. A dry etching device characterized by being exposed outside the container. (2) The dry etching apparatus according to claim 1, further comprising means for evacuating a space corresponding to the optical path between the mask and the ultraviolet light or X-ray source. (3) Dry etching Wf'f according to claim 1 and mechanism 2, wherein the mounting table is completely equipped with heating or cooling means. (4) The mask is characterized by being composed of a substrate that transmits ultraviolet light or X-rays, and a mask pattern formed on the surface of this substrate that is made of a material that absorbs or reflects ultraviolet light or X-rays. Dry etching apparatus R1 according to claim 14, 2 or 3