JPS6050927A - Thin film formation - Google Patents

Abstract

PURPOSE:To contrive the large improvement of the speed of film deposition by a method wherein the sputtered surface of a target material is previously processed to unnevenness. CONSTITUTION:Electrodes 2 and 3 are arranged in opposition in a sputter chamber container 1. The high frequency power from a high frequency power source 5 is impressed on the electrode 2. The target material 6 is placed on the lower surface of the electrode 2. The surface of this material 6 is processed so as to have a cross-section of e.g. triangular waveform. On the other hand, a substrate 7 is mounted on the electrode 3. In such a manner, when ions accelerated by cathode drop voltage advance vertically to the cathode, most of the ions collide with the surface of the target 6 obliquely, because the surface of the target 6 is not flat. This manner enables the increase in the amount of atoms sputtered from the target 6. This is because the efficiency of sputtering has the dependency on an angle of incidence, and because the sputtering effect reduces in the case of vertical incidence.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a thin film forming method using a sputtering method.

[Technical background of the invention and its problems]

Conventionally, a sputtering method has been used as one method for forming a thin film on a substrate such as a semiconductor wafer. In the general sputtering method, 10-1 to 10' [to
An abnormal glow discharge is caused in a vacuum of about 100 mm, and the positive ions are accelerated and bombarded to the cathode by the cathode falling voltage. On this occasion,
The constituent atoms of the target material placed in the cathode section are ejected by sputtering of cations. and,
A thin film is formed by depositing atoms emitted from this target material onto a substrate.

However, this type of method has a problem in that the film deposition rate is slow and it takes a long time to obtain a desired thick film. In other words, the deposition rate of a film can be increased to some extent depending on sputtering conditions such as power supply output and pressure, but for example, the deposition rate of an insulating film such as a silicon oxide film is usually around 100 people/min. It is several times slower. Therefore, in order to increase productivity, it is necessary to increase the target area and form films on multiple substrates simultaneously, but in this case, the power supply capacity needs to be increased and the equipment is also expensive. becomes.

[Purpose of the invention]

An object of the present invention is to provide a thin film forming method that can significantly increase the film deposition rate and improve productivity without requiring fundamental improvements to sputtering equipment.

[Summary of the invention]

The gist of the present invention is to improve the surface shape of the target material,
The purpose is to increase the amount of atoms emitted from the target material by sputtering.

Conventionally, the surface shape of the target material is generally flat. The amount of atoms ejected from the target material is much greater when the ions are incident from an oblique direction (particularly at an angle of incidence of 45 degrees) than when the ions are incident perpendicularly. Therefore, it is considered that by processing the surface of the target material into an uneven shape, the amount of atoms emitted from the target material increases.

The present invention focuses on these points, and uses ions generated by electric discharge to target the target! - A thin film forming method using a sputtering method in which a material is sputtered and a thin film is deposited on a predetermined substrate surface, in which the surface of the target material to be sputtered is processed to be roughened in advance.

〔Effect of the invention〕

According to the present invention, when ions accelerated by the cathode falling voltage come perpendicular to the cathode, most of the ions collide obliquely with the target surface because the target surface is not flat as in the conventional case. , which increases the amount of atoms sputtered from the target. This is because the sputtering efficiency is dependent on the angle of incidence, and when the incidence is perpendicular, the "sputtering effect" becomes smaller.

For example, when sputtering SiO2 tags 1 to 1 with Ar ions, when the incident angle is 45 degrees, the sputtering effect is about 5 times greater than when the incidence is perpendicular. This results in an increased rate of thin film deposition on the substrate. Furthermore, since the angular distribution of atoms ejected from the target becomes wider, the shape of the film covering the stepped portion of the substrate is also improved.

[Embodiments of the invention]

FIG. 1 is a sectional view showing a schematic configuration of a sputtering apparatus used in a method according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a sputtering chamber container, and inside this container 1, flat electrodes 2 and 3 are arranged facing each other. High frequency power from a high frequency power source 5 is applied to the upper electrode 2 via a matching box 4 . A target material 6 made of quartz glass (SiO2) is placed on the lower surface of the electrode 2, for example, when forming a silicon oxide film. The surface of this target material 6 is processed to have a triangular wave-like cross section with a pitch of 2 [s], as shown in an enlarged view in FIG. Note that cutting with a diamond or the like or etching may be used for this processing. The lower electrode 3 is normally installed, and the substrate 7 is placed on top of this.

In the figure, 8 indicates a gas introduction port for introducing gas into the container 1, and 9 indicates a gas exhaust port for discharging the gas within the container 1. Further, 10 indicates an insulator.

Next, a case will be described in which a silicon oxide film is formed using the apparatus configured as described above. First, inspect the inside of container 1 by
After evacuation to a degree of vacuum of about 10 [torr], for example, Ar gas is introduced from the gas inlet 8 to maintain the gas pressure inside the container 1 at 1Q [1 tOrr]. Next, the high frequency power is set to 1 KW, for example, to generate a discharge between the electrodes 2 and 3, and the target material 6 is sputtered with Ar ions to deposit a silicon oxide film on the substrate 7. The distance between Targetera 1 to Material 6 and the substrate 7 was 7.5 [cm].

The deposition rate of the silicon oxide film under the above conditions was 450 people/min. Target material! In the case of a conventional film with a flat surface such as '16, the deposition rate under the same conditions as above is 80 [man, 'man]. That is, by the method of this example, the deposition rate was increased by more than five times by simply changing the surface shape of the target material.

Note that the present invention is not limited to the embodiments described above. For example, the surface shape of the target material is not limited to that shown in FIG. 2; it may be processed so that the surface is not flat but has many sloped parts.

Further, the target material is not limited to quartz, and may be used as appropriate depending on the type of film to be formed.

Furthermore, the configuration of the apparatus is not limited to that shown in FIG. 1, and can be modified as appropriate as long as it is a sputtering apparatus equipped with a pair of parallel plate electrodes. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic configuration of a sputtering apparatus used in a method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an enlarged view of the materials used in the apparatus. 1... Empty sputtering container, 2, 3... Electrode, 4...
Matching box, 5... High frequency power supply, 6... Target, 7
... Board, 8 Gas inlet, 9... Gas exhaust port, 10
···Insulator.

Claims (2)

[Claims] (1) A method for forming a thin film by a sputtering method in which a target material is sputtered with ions generated by electric discharge to deposit a thin film on a predetermined substrate surface, characterized in that the surface of the target material to be sputtered is processed to be roughened in advance. A method for forming a thin film. (2) The thin film forming method according to claim 1, wherein the surface of the target material to be sputtered is processed so that the cross section has a triangular wave shape. 3) The thin film forming method according to claim 2, wherein the triangular wave shape in the surface irregularities of the target material is an isosceles triangle with one angle of 90 degrees.