JPS5989768A - Formation of thin film - Google Patents

Abstract

PURPOSE:To form a thin film having an optional compsn. ratio on a substrate with good reproducibility by disposing plural targets which permit independent impression of a voltage in a chamber, measuring the intensity ratio of the excitation light from each target in the stage of sputtering and adjusting the sputtering condition of each target. CONSTITUTION:A W target 12 and an Si target 13 are disposed in a chamber 4, and are connected respectively to power sources 18, 19 which are adjustable in voltage. A GaAs substrate 8 is mounted, via a slide shutter 11, to a holder 7. The inside of the chamber 4 is evacuated to high vacuum and gaseous Ar is introduced therein. An electric field is applied between the holder 7 and the targets 12, 13 to generate a sputtering phenomenon. The radiation light of a W atom and an Si atom is measured with an ammeter 17, via a monochromator 15 and a photoelectron multiplier 16 on the outside of a quartz window 14 provided on the side wall of the chamber and the voltage of the power sources 18, 19 on the targets 12, 13 is regulated according to the intensity ratio of the light radiated from W and Si. A thin film consisting of the metal having a specified compsn. ratio is thus formed on the substrate 8.

Description

[Detailed description of the invention] (a) Technical field of the invention The present invention relates to a method for forming a thin film having an arbitrary component ratio.

(b) Technical background Silicon (Si) and high melting point metals are used as electrode metals for semiconductor IO or FET (field effect transistor), such as tungsten (W), molybdenum (MoJ, and titanium).
) etc., such as W
8i, Mo811, and TiSi2 are used.

Such silicides have low resistivity, high melting points, and are stable and difficult to diffuse even during high-temperature processing of semiconductors, so they are useful and widely used in processes that require heat treatment. Here, since 8i behaves almost as a metallic element when combined with the fireflies, the above composition or a small number of component ratios can be obtained, resulting in different resistivities and melting points. The present invention relates to a method for forming such a thin film made of multi-component metals by sputtering with sufficient component ratios and with good flexibility.

(C) Prior Art and Problems FIG. 1 is a block diagram of a sputtering apparatus used for conventional thin AlK construction.

Hereafter, W58i3 on gallium arsenide (GaAs) single crystal substrate
A case of forming a thin film of tungsten silicide having a composition will be described as an example.

The exhaust line of this device consists of a combination of Sogusho/Ho/Nol and a cryo pump 2. First, the roughing pulp 8 is fully opened to exhaust the inside of the chamber, and then the chamber is switched to the final exhaust pulp 5. Evacuate the inside to vacuum.

Next, a small amount of argon (Ar) gas is introduced into the entire chamber 4 by opening it so that the vacuum level in the chamber is maintained within the range of 10 to 10 (torr) throughout the sputtering.

Note that the Ga
The As substrate 8 was previously placed on the sample holder 7 connected to the anode in a water-cooled structure, while the As substrate 8 was placed on the sample holder 7 connected to the anode in a water-cooled structure.

A target 9 made of Si1 is provided opposite to this and connected to the cathode side of a power supply lO.Also, a slide shutter 11 is provided in front of the GaAs substrate 8.
This is because before the start of sputtering, the surface of the target 90 is contaminated by gas adsorption, etc., and as a result, foreign or unstable precipitation is likely to occur.
It comes out to protect the substrate 8 and prevent this precipitation.

In order to form a thin film of silicide made of W and Si3 on the GaAs substrate 8 using such a sputtering device, a voltage is applied between the sample holder 7 and the target 9, and the A
The gas plasma consisting of R is spread throughout the entire area, and Ar ions collide with the duck-Si target 9, scattering W68js in the form of K atoms and depositing them on the GaAs substrate s.

Conventional targets in such sputtering apparatuses have been used by sintering powder left over from this configuration.

For example, in this embodiment, W and SiB were mixed and sintered so as to have the same composition ratio, and used as the target 9.

However, in this case, since the target 9 is porous, a large amount of oxygen (0), nitrogen (N), etc. is adsorbed, making it difficult and rare to form a highly pure thin film. Additionally, since the sputtering rate differs depending on each metal atom, the surface composition of the target during the sputtering process will be different from the inside of the target, resulting in the problem that the composition of the thin film formed on the GaAs substrate will also be different. Rarely.

A method to solve all of these problems is to create multiple targets (in this case, a W target and a Si target) whose voltage can be controlled independently, and to melt each metal and use it in the form of an ingot. This was also done.

However, in this case, there is mutual contamination between the targets, and the roughness of the surface due to the progress of sputtering differs depending on the target constituent metal, so the sputtering rate gradually changes from the initial state, resulting in a change in the composition of the thin film formed. There was a problem that it was different from the prescribed one.

(d) Purpose of the Invention The purpose of the present invention is to provide a method for forming a thin film made of multi-component metals in a fixed composition ratio on a substrate by sputtering.〇(e) Structure of the Invention Purpose of the Present Invention In this method, a substrate on which a thin film is to be formed is placed in a chamber facing a plurality of targets to which voltages can be applied independently, and when the targets are sputtered by collision with one ounce of inert gas, a This can be achieved by depositing a thin film having an arbitrary composition ratio by fixing the excitation light intensity ratio t-I11 and adjusting the sputtering conditions for each target.

(f) Embodiments of the Invention The present invention measures the intensity of excitation light from a plurality of targets made of thin film constituent metals, and forms a thin film sound with a constant composition ratio by keeping the intensity ratio at a specified value. .

FIG. 2 is a block diagram of a sputtering apparatus implementing the present invention, which includes a slide shutter 11 and a plurality of target blades 12.
A quartz window 14 is disposed on the side wall of the chamber between the quartz window 18 and the quartz window 18, and a monochromator 15 and a photomultiplier tube 16 are disposed outside the quartz window 69, and an ammeter 17 can measure the sputtering intensity of each target.

In addition, in FIG. 2, there are a plurality of targets, that is, in this example, two targets, the W target 12 and the Si target 1B.
There are two power supplies, each equipped with an adjustable voltage power supply 18,19.

Inject argon (Ar) gas into chamber 4 for 4 people.
A sample holter 7 and a W target 1 are connected to the anode of a power source 18 and 19, and a GaAs substrate 8 is mounted and held thereon.
When an electric field is applied between the power supplies 18 and 19 between the W target 1 and the Si target 13, a gas plasma consisting of Ar ions is generated, and the W target 1 of Ar ions is generated.
2 and S1, a sputtering phenomenon occurs due to the collision with the S1 target 1B. At the same time, some W atoms and 8i atoms are excited to the high platelet position, and then emit the original metal at a wavelength unique to each atom in order to return to the base key position.

In order to detect such emitted light, the present invention provides a quartz window 14' on the side wall of the chamber between the slide shutter 11 and the target 12.18, and monitors the exbattery rate (velocity) of the light passing through the window 14'. That is, although the interior of the chamber 4 contains light of various wavelengths such as light from Ar in addition to light emitted from WSSi, the present light source 8A uses a monochromator 15 to completely separate the unique light from W and Si.
The light intensity is measured by a radio meter 17 through a photomultiplier tube 1t1.

Note that the relationship between the emitted light intensity ratio of W and Si and the composition ratio of the alloy with respect to the ratio must be determined in advance.

In this way, the emitted light intensity ratio of the constituent components is measured throughout the sputtering, and each target is
By adjusting the voltage of the power supply 18 and 19 in 2.18, it is possible to make a thin film without compositional fluctuation.

Furthermore, since the synchrotron radiation measuring device according to the present invention is installed between the shutter 11 and each target lens (12.18), after setting the intensity ratio of the synchrotron radiation to a predetermined value at the time of press sputtering,
Slide shutter 1ft-open book sputtering may be performed.

Although this example describes the case where a binary alloy is formed on a # conversion semiconductor substrate, by increasing the number of targets, a multi-component alloy thin film can be formed. When a thin film is formed using a sputtering method, the sputtering rate is different, which tends to result in a thin film with a different component composition at the start and end of sputtering. However, by implementing the present invention, it is possible to stably form a thin film with any component dead metal. Now you can get it.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional Sunokutsuta device, and FIG. 2 is a block diagram of a Sunokutsuta device according to the present invention. In the figure, 4 is a chamber, 7 is a sample holder, and 8 is a GaAs substrate. , 9.12.18 is the target, lU, lB, 19 is 'Kamegen 0 Mi 1 Tsutsuta 20

Claims (1)

[Claims] A substrate on which a thin film is to be formed is placed in a chamber facing a plurality of targets to which voltages can be applied independently, and when performing T-sputtering by collision with inert gas ions, excitation from each target is generated. A method for forming a thin film, characterized in that a thin film having an arbitrary composition ratio is formed on the substrate by measuring the light intensity ratio and carefully adjusting the sputtering conditions vI of each target.