JPS5819479A - Method and device for etching - Google Patents

Abstract

PURPOSE:To perform uniform etching surely with no variance in etching in the stage of dry etching of thin films in the production of semiconductor integrated circuits by forming active radicals with light energy. CONSTITUTION:A sample 5 to be etched is placed on a sample table 6 which is rotated by a motor 7 in a reaction chamber 1. The inside of the chamber 1 is maintained in a pressure atmosphere of about 10<-2>-10 torr ''Freon '' type gas such as CClF2, and UV rays are irradiated from a UV lamp 9. The UV rays are made into parallel rays by a convex lens 4, by which their energy is dispersed uniformly. The rays pass through the gas and generate active radial seeds uniformly, thereby permitting the uniform etching of the sample 5 on the rotating table 6 with no variance. Etching reaction is effected safely by the use of the UV rays without using plasma for the purpose of obtaining active radicals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry etching method for thin films used in the manufacture of semiconductor integrated circuits and an apparatus therefor.

In the process of manufacturing semiconductor integrated circuits, thin film etching is carried out by the so-called plasma etching method, which uses discharge plasma of a gas containing vine atoms that serve as the etchant, in order to obtain active radical species that serve as the etchant for etching the film to be etched. ing. However, in this method, the sample comes into direct contact with the plasma, the temperature of the sample rises to 755130°C to 150°C, and the resist used as a mask during etching deteriorates during etching (for example, Shipley etching, which has a softening point of about 130°C) For resist manufactured by A21350 J, the sample temperature was 75:130.
The resist nos and turns formed on the sample surface are thermally deformed at temperatures between 150°C and 150°C), and the fidelity of the A-turns formed on the thin film with respect to the original 9 turns of the mask also deteriorates. Furthermore, since the sample is placed in the discharge plasma with a force greater than or equal to the force, the etching state of the thin film is affected by the non-uniformity of the electric field. Furthermore, there were other problems such as damage caused by radiation generated in the ion sheath.

SUMMARY OF THE INVENTION In order to solve these problems, an object of the present invention is to provide a dry etching method and an apparatus therefor in which active radicals in dry etching are obtained using light energy.

Next, dry etching according to the present invention will be explained based on examples. FIG. 1 shows a first embodiment of dry etching according to the present invention, in which light energy is obtained from ultraviolet rays. In the figure, a reaction chamber 1 is equipped with a gas inlet 2 and a gas outlet 3, and is made of carbon such as quartz.
A convex lens 4 having a focal length f and made of a material that is not easily corroded by UV rays and that transmits ultraviolet light is mounted parallel to and facing a sample stage 6 on which a sample 5 to be etched is placed. The sample stage 6 is rotated by a motor 7 via a transmission shaft 8, and includes an ultraviolet lamp, which essentially acts as a point light source.
9 (for example, UXM 500 MA manufactured by Ushio Inc.) is attached to the focal point 1o of the convex lens 4 on the side opposite to the reaction chamber 1.

The light irradiated from the ultraviolet lamp 9 placed at the focal point of the convex lens 4 becomes a parallel light beam after passing through the convex lens 4, and the energy is uniformly dispersed, so that the generation of active radical species is also uniform, and the thin film is uniformly formed. Etching progresses.

Next, the operating method and operation of the dry etching apparatus constructed as described above will be explained. Freon gas (e.g. CC1F2) is introduced from the gas inlet 2, and while exhausting from the gas outlet 3, the pressure inside the reaction chamber 1 is set to 10-2 to 10 Torr.
Set to a constant pressure between r. After that, when the ultraviolet lamp 9 is turned on, parallel ultraviolet rays are irradiated into the reaction chamber 1 through the convex lens 4, and radical decomposition of CF2Ct2CF2C or +C occurs due to the ultraviolet irradiation, and active radical species C are highly efficiently converted.
t. is obtained. The thus obtained active radical species Ct. performs an etching action on various thin films through the following reaction. For example, Si±4 C1・→
5iCt4↑ At+3 C→htct, ↑ Mo +5 CL−→MoCl5↑ Ti + 4 C→T i Ct4↑ (↑ indicates vaporization) FIGS. 2 and 3 show the second embodiment of the present invention In this embodiment, optical energy is obtained from a laser beam.

A reaction chamber 1 equipped with a gas inlet 2 and a gas outlet 3 is made of a material having high transmittance in the infrared region, such as CdTe 5ZeSe.
Windows 11 and 12 made of a material such as 1KCt single crystal are arranged opposite to a sample stage 6 on which a sample 5 to be etched is placed. As a result, the carbon dioxide laser 13 is oscillated toward the heat absorber 14 outside the reaction vessel, and the window 11
．． The laser beam 15 that has passed through the laser beam 12 is irradiated into the reaction chamber 1 as parallel light.

The sample stage 6 is rotated by a motor 7 via a transmission shaft 8.

Next, the dry type 1. How to operate the ramp device and its operation will be explained. Freon gas (for example, cctv3°CCl2F3) is introduced through the gas inlet 2, and while being exhausted through the gas outlet 3, the pressure inside the reaction chamber 1 is set to a constant pressure between 10 Torr and 10 Torr. After that, when carbonic acid, which exhibits strong oscillations around 940α, is irradiated with a slaser, C-F stretching vibrations that exhibit strong absorption around 1000 crn are excited, causing the reaction shown below.

In reaction (1), 1102cr in CC4F3
In reaction (2), the stretching vibration of the C-F bond of n-' is the C-Ct bond of 923 cm in CCl2F3,
The stretching vibration of the C-F bond of 1098Crn-1 was measured by carbon dioxide laser at 1099cm, 921cIIL, 1
It was excited by 088CIl+ light. Furthermore, in these reactions, the amount of heat generated during the reaction is very small because the laser beam is selectively excited with a frequency extremely close to the stretching frequency of the C--F or C--Ct bond.

The active radical species C generated in this manner perform an etching action on various thin films by the reaction described in the first embodiment.

As explained above, in the dry etching of the present invention, a plasma reaction is not used to obtain active radicals, so the reaction gas and reaction chamber are kept at room temperature even during etching, and therefore the resist used as a mask material is This has the advantage that deterioration due to heat, variation in the etching state due to local non-uniformity of the electric field, and damage to the ion sheath due to radiation do not occur.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of one embodiment of the etching apparatus according to the present invention, and FIG. 3 is a top view of the apparatus shown in FIG. 4... Convex lens, 9... Ultraviolet lamp, 1o...
Focus of convex lens 4, 11.12... Window, 13... Carbon dioxide laser, 14... Heat absorber-115
···Laser beam. One word Δ

Claims (8)

[Claims] (1) An etching method characterized in that an active radical species F or C is obtained by applying optical energy to a molecular gas containing F or Ct. (2) The etching method according to claim (1), wherein the light energy is ultraviolet rays. (3) The etching method according to claim (1), wherein the pattern light energy is Rede light. (4) In an etching apparatus having a reaction chamber having a gas inlet and an outlet for introducing a molecular gas containing F or Ct, and a holder for an object to be etched provided in the reaction chamber, the reaction chamber is equipped with a light-emitting device. An etching apparatus characterized in that a transmission window is formed and a light irradiation section is provided for supplying light energy into a reaction chamber through the light transmission window. (5) The etching apparatus according to claim (4), wherein the light transmitting window is formed of a convex lens that transmits ultraviolet rays, and the light irradiation section is an ultraviolet rung. (6) The etching apparatus according to claim (5), wherein the convex lens is arranged parallel to the surface of the object holder. (7) The etching apparatus according to claim (5) or (6), wherein the ultraviolet lamp is disposed at the focal point of the convex lens. (8) # The etching apparatus according to claim (4), wherein the light irradiation section is a Raded light oscillation device.