JPH01129967A - Thin film processing device - Google Patents

Abstract

PURPOSE:To control film thickness with high accuracy over a long period of time by detecting the spectra of plasma emitted light with a spectrum detector disposed on the outside of a vacuum vessel and computing the growth speed of film thickness from the intensity thereof. CONSTITUTION:A substrate 3 and a flat plate target 5 are disposed to face each other in parallel in the vacuum vessel 1 and a gaseous plasma raw material of a low gaseous pressure is introduced into the vessel. A DC or high frequency power supply 9 is connected between the substrate 3 and the target 5 to generate plasma on the target surface. Sputter particles are thereby generated from the target 5 and the thin film is formed on the substrate 3. The spectra of the plasma emitted light are detected by a condensing part 17 of the spectrum detector 18 disposed on the outside of the vessel via a view port 12 provided to the wall of the vacuum vessel 1 of the above-mentioned thin film processing device. The numbers of atoms to be generated in the unit time are detected from the intensity of the emission spectra of the target 5 material contained in the plasma emitted light and the growth speed of the deposited thin film is computed. The sputtering time is thereby controlled and the prescribed film thickness is exactly and stably obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method in which a substrate on which a thin film is formed and a flat target made of the material of the thin film are opposed to each other in parallel with an interval in a vacuum container. At the same time, low pressure plasma source gas is introduced, and a direct current or high frequency alternating current power source is connected between the substrate and the target to generate ions in the plasma generated on the target surface perpendicular to the surface of the target. The present invention relates to a thin film processing device that forms a thin film on a substrate by generating sputtered particles by accelerating them using an electric field and colliding them with a target.

[Conventional technology]

FIG. 2 shows the configuration of a conventional thin film processing apparatus. A vacuum container 1 constituting the apparatus 9 houses a substrate 3 attached to the vacuum container via a susceptor 2 on which a thin film is formed on the surface, and a flat plate made of the material of this thin film. A target 5 is arranged to face the substrate 3 in parallel with a space therebetween.A low-pressure plasma source gas is introduced into the vacuum vessel 1, and an exhaust device (not shown) is operated to exhaust the vacuum vessel. When a high frequency voltage is supplied between the substrate 3 and the target 5 via the water-cooled conductor 6 from the high frequency power source 9 while maintaining the gas pressure in the target 1 at a predetermined value, and plasma is generated on the target surface, ions in the plasma is accelerated in the direction of the electric field and collides with the target 5, sputter particles are generated from the target surface, and these sputter particles adhere to the surface of the substrate 3 to form a thin film.The reference numeral 4 in the figure indicates the initial stage of sputtering. This is a shutter that is interposed between the substrate and the target and is opened after the target surface has been sufficiently purified to start forming a thin film on the substrate.

Traditionally, people indulge in such devices. The thickness of the thin film formed on the substrate surface has been controlled by using a crystal in the sensor head 7 inserted into the vacuum container 1. That is,
The vibration frequency of the crystal, which changes as atoms of the sputtered target material adhere to the sensor head 7, is converted into film thickness and monitored by the monitor 8.

[Problem that the invention seeks to solve]

However, in such a method, the life of the sensor head is short, and the sensor head must be replaced frequently, making the operation of the apparatus complicated. In addition, in the case of sputtering that uses magnetron sputtering to generate high-density plasma on the target surface to increase the density of sputtered particles, the gas pressure in the vacuum chamber,
The scattering distribution of sputtered particles changes greatly due to changes in sputtering conditions, such as the voltage applied between the substrate and the target, the distance between the substrate and the target, and the number of sputtered particles that reach the sensor head and the number of particles that reach the substrate. Since the ratio of the sputtering conditions changes, it is necessary to perform correction each time the sputtering conditions are changed, and film thickness control is troublesome. Furthermore, high power R
F sputter (RF is radio frequency, usually 13.5
6), the distance between the substrate and target becomes large, and the sensor head enters the vacuum chamber, which may disturb the electric field between the substrate and target and cause abnormal discharge. Become.

An object of the present invention is to provide a thin film processing apparatus equipped with a film thickness sensor that enables accurate film thickness monitoring at all times without being affected by changes in sputtering conditions and therefore without replacing the film thickness sensor. It is to be.

[Means for solving problems]

In order to achieve the above object, according to the present invention, a substrate on which a thin film is to be formed and a flat target made of the material of the thin film are disposed in parallel and facing each other with a space between them, and a low Plasma raw material gas at atmospheric pressure is introduced, and a direct current or high frequency alternating current power source is connected between the substrate and the target, and ions in the plasma generated on the target surface are generated perpendicular to the surface of the target. In a thin film processing device that forms a thin film on a substrate by generating sputtered particles by accelerating them with an electric field and colliding them with a target, a view port is provided on the wall of the vacuum container to transmit light, and the light is transmitted through the view port. A spectrum detector for detecting the spectrum of plasma emission is placed outside the vacuum vessel together with its sensor head.

[Effect]

First, the principle of the present invention will be explained.

Atoms ejected from the target by the collision of ions in the plasma are excited in the plasma and emit light, exhibiting an emission spectrum unique to the target material. This luminous spec.
Since the intensity of the torr is proportional to the number of atoms ejected per unit time, the growth rate of the film thickness can be determined by detecting this intensity. Therefore, by monitoring the sputtering time from the start of thin film formation, the thickness of the film formed on the substrate can be known. Therefore, by disposing such a spectrum detector outside the vacuum vessel, it becomes possible to always monitor the correct film thickness without being affected by changes in sputtering conditions.

〔Example〕

FIG. 1 shows the configuration of a thin film processing apparatus according to an embodiment of the present invention. A view port 12 that transmits light is provided on the wall of the vacuum container 1 constituting the apparatus, and a light condensing section 17 as a sensor head is disposed outside the vinyl-bow eye 2.
7 is connected to a spectrum detector 18 via an optical cable 11. This spectrum detector 18 is connected to a data processing section 10 that performs predetermined calculations using the spectrum intensity of a specific wavelength detected by this detector as input.

In the thin film processing apparatus configured as described above, when sputtering is started by supplying a high frequency voltage from the high frequency power source 9, the plasma source gas introduced into the vacuum chamber 1 emits plasma and ions in the plasma are emitted. Atoms ejected from the target by the collision are excited in the plasma and emit light, exhibiting an emission spectrum unique to the target material. Since the intensity of this emission spectrum is proportional to the number of atoms that can be ejected per unit time, the light converging section 17
The light is focused by the spectrum detector 1 via the optical cable 11.
The film thickness growth rate on the substrate can be monitored by detecting the intensity of the emission spectrum specific to the target material from the light emission inside the vacuum vessel 1 guided by 8 and inputting this to the data processing unit 10. . However, if only the emission spectrum of the target material is monitored, it is difficult to quantitatively evaluate the detected emission spectrum intensity because the spectral intensity changes depending on the input power, the measurement point in the plasma, etc. Can not. However, the ratio of the emission spectrum intensity of the target material and the emission spectrum intensity of the plasma source gas is almost constant at any measurement point as long as the measurement points are the same. In addition to determining the relationship between the emission spectrum intensity of the material and the film thickness growth rate in advance, the emission spectrum of Ar, which is a stable plasma source gas, is simultaneously monitored to determine the relationship between the emission spectrum intensity of the plasma source gas and the emission spectrum intensity of the target material. By performing thin film processing while making a comparison and confirming that there is no change in this ratio, it is possible to perform reliable quantitative evaluation of the emission spectrum intensity from the target material.

[Effect of Gyomei]

As described above, according to the present invention, in the vacuum container,
A substrate on which a thin film is to be formed and a flat target made of the material of the thin film are placed facing each other in parallel with a gap between them, and a low pressure plasma raw material gas is introduced to create a direct current or A high-frequency AC power source is connected to generate ions in plasma on the target surface, which are accelerated by an electric field generated perpendicular to the surface of the target and collided with the target to generate sputtered particles and form a thin film on the substrate. In the thin film processing apparatus for performing this, a view port for transmitting light is provided on the wall of the vacuum container, and a spectrum detector for detecting the spectrum of plasma emission transmitted through this view port is arranged outside the vacuum container together with its sensor head. Therefore, (1) Abnormal discharge caused by the sensor head, as in the conventional case, is eliminated and stable discharge is obtained, so a thin film of good quality can be obtained.

(2) Since the monitoring results are not affected by the scattering distribution of sputtered particles, accurate film thickness control is possible.

(3) Since the sensor head is not contaminated, it can be used semi-permanently and there is no need to replace it as often as in the past, reducing the operating cost of the device.

Effects such as this can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a thin film processing apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the configuration of a conventional thin film processing apparatus. 1 Vacuum container, 3 Substrate, 5-Target, 7 Sensor head, 9 High-frequency power supply, 10.-Data processing section, 12
Viewport, 17.・Light condensing part (sensor head),
18 Spectrum detector. Figure 1 Figure 2

Claims (2)

[Claims] (1) In a vacuum container, a substrate on which a thin film is to be formed and a flat target made of the material of the thin film are arranged parallel to each other with a space between them, and a low pressure plasma raw material gas is introduced into the substrate. A direct current or high frequency alternating current power source is connected between the target and the target, and ions in the plasma generated on the target surface are accelerated by an electric field generated perpendicular to the surface of the target and collided with the target, thereby removing sputtered particles. In a thin film processing apparatus that forms a thin film on a substrate by generating plasma, a view port is provided on the wall of the vacuum chamber to transmit light, and a spectrum detector for detecting the spectrum of plasma light transmitted through this view port is installed in the sensor head of the thin film processing apparatus. and disposed outside the vacuum container, detecting the intensity of the emission spectrum from the target material included in the plasma emission, calculating the growth rate of the film deposited on the substrate, and controlling the sputtering time to obtain a predetermined film thickness. Thin film processing equipment featuring: (2) In the thin film processing apparatus according to claim 1, the detection of the emission spectrum intensity from the target material is performed together with the detection of the emission spectrum intensity by the plasma raw material gas introduced into the vacuum container. Characteristic thin film processing equipment.