JPH01166525A - Controlling method for sputtering step and the like - Google Patents

Abstract

PURPOSE:To enhance the controlling accuracy of step conditions by introducing discrete spectra having a specific wavelength of emission spectra of a plasma to a Fabry-Perot interferometer, analyzing its ultrafine structure, measuring the speed of atoms or molecules of corresponding exciting state, and feeding it back. CONSTITUTION:Ar is introduced between a target 1 made of Co and a substrate 2, a high frequency voltage is applied thereto, thereby generating a plasma. The positive ions of the Ar are collided to the target 1, atoms discharged therefrom are deposited on the substrate 2, and a thin Co film is formed. One or several discrete spectra existing in a specific wavelength range of an emission beam of Co atoms is noticed, selected by a filter 4, and introduced to a Fabry- Perot interferometer 7. In the interferometer 7, it is multi-reflexed by an etalon plate 8, interfered by reflected light and transmitted light, and the speed of the atoms is measured. The speed of the atoms is fed back to the step thereby to maintain an optimum manufacturing conditions, thereby enhancing the controlling accuracy.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a technology for controlling process conditions in sputtering equipment, etc. used to apply plasma to form metal thin films during semiconductor manufacturing. In the process of forming or etching a metal thin film on a substrate using plasma, the aim is to control the thin film formation atoms, gas molecules, and/or atoms in the plasma with good control and reproducibility. A discrete spectrum in a specific wavelength region of the emission spectrum is introduced into a Fabry-Perot interferometry spectrometer (7), and its ultrafine structure is analyzed.
The present invention constitutes a method characterized by measuring the speed of atoms or molecules in a corresponding excited state and feeding this back to the process to control process conditions.

[Industrial application field]

The present invention relates to a sputtering apparatus used to form a metal thin film by applying plasma during the manufacture of semiconductors, and more particularly to a technique for controlling process conditions when forming a metal thin film.

[Conventional technology and its problems]

In sputtering equipment, an inert gas such as argon is introduced between the target and the substrate, a high voltage is applied to it to form a plasma, and the positive ions of the inert gas generated in the plasma collide with the target. The target atoms ejected from the target are deposited on the substrate to form a metal thin film.

Conventionally, three factors have been selected to control process conditions during thin film formation in a sputtering apparatus: sputtering power, substrate temperature, and pressure of gas (for example, argon, oxygen, etc.) flowing in during sputtering. By controlling these factors, a large part of the thin film formation conditions can be well controlled, but there are many variations in the magnetic properties, mechanical properties, or structural properties of the film, which can be difficult to scale from small experimental equipment to large production equipment, for example. When upgrading, the manufacturing conditions were completely different and there were cases where reproducibility was not possible.

In order to solve this problem, attempts have been made to control the thin film formation conditions by measuring the characteristics of the plasma itself generated during sputtering. Observations are being made using spectroscopic analysis.

However, even with these methods, the relationship between the factors and the properties of the formed thin film was unclear, and the methods were insufficient for use in process control.

[Means for solving problems]

In order to solve the above-mentioned problem, the present inventors conducted intensive research and measured the fine structure of the emission spectrum lines generated from plasma using a Fabry-Perot interferometry spectrometer, and the results obtained therefrom. The present invention was completed based on the discovery that highly accurate process control is possible if this is reflected in the conditions during thin film formation.

That is, in the process of forming or etching a metal thin film on a substrate using plasma, the present invention provides a process for forming a metal thin film on a substrate by using a specific wavelength out of the emission spectrum of thin film forming atoms, gas molecules, and/or atoms in the plasma. Introducing a discrete spectrum with a value of The present invention provides a method characterized by:

As the discrete spectrum in the specific wavelength range, it is desirable to select one in which there is no other discrete spectrum that overlaps with the wavelength range in the vicinity of the specific wavelength range.

The present invention can be suitably applied to the control of so-called sputtering equipment for forming metal thin films used in the manufacture of semiconductors, etching equipment for etching lines on metal surfaces, and the like.

The feature of the present invention is that, like conventional emission spectrum analysis, it is possible to observe and determine in which wavelength range the excited state emission line exists by observing the entire spectrum as shown in Figure 1. However, by using a well-known Fabry-Perot interferometry spectrometer, we focus on one of the emission spectrum lines in a specific wavelength range, for example, the emission line A in the figure, and from the fine shape of that line, we can determine the velocity of atoms, etc. The point is to find the value of the parameter.

The principle of determining parameters using such a Fabry-Perot interferometry spectrometer is based on, for example, Max Horn.

It is described in "Principles of Optics IIJ" by Emil Wolff (translated by Toru Kusayo and Hidetsugu Yokota, Tokai University Press), p. 455.

FIG. 1 is a diagram for explaining the above-mentioned present invention in detail.
Argon is introduced as an inert gas between the target l made of cobalt used for manufacturing a nickel horizontal magnetization recording medium and the substrate 2, and the temperature is 10-'' to 1 O-'Torr.
In a vacuum atmosphere of 1 shows a sputtering apparatus 3 for depositing cobalt (atoms) onto a substrate 2 to form a thin film of cobalt. A considerable portion of the emitted target atoms are ionized or in an excited state, and emit an emission spectrum unique to that atom. FIG. 3 shows this device in more detail, and the light emitted by the plasma is taken out through windows 6A to 6D provided at predetermined locations in the sealed housing 5 of the device, and is then taken out into a Fabry-Perot interferometry spectrometer. It is configured to be introduced in

[For production]

In the present invention, the observed emission line of cobalt atoms (
Wavelength range λ=360.208nm, 351.83nm, 3
By focusing on one or several discrete spectral lines existing in a specific wavelength range among 45.35 nm, 341.234 nm, -), and passing it through the filter 4, only the spectrum in the selected wavelength range is extracted. The sample is introduced into a Fabry-Perot interferometry spectrometer 7. This spectrometer 7 has a reflective film on the opposing surfaces of two glass plates with good flatness (λ/300) called etalon plates 8, and transmits light between these two surfaces. This method uses multiple reflections to cause mutual interference between the reflected light and the transmitted light, and measures the velocity, or kinetic energy, of the atoms that produced the spectrum according to a known method from the line width of the interference fringes due to the Doppler effect. .

In the case of this example, the amount of energy held by the cobalt atoms ejected from the target l has a clear causal relationship with the state of deposition of the atoms on the substrate 2. Formation status of thin film,
It is predicted that this will have a significant impact on Therefore, if the determined atomic speed is fed back to the process using a known control method, optimal manufacturing conditions can be maintained. Of course, the measured emission spectrum may be due to the inert gas atoms or molecules that caused the cobalt atoms to be ejected. This control can be used for process control of an etching device that utilizes the etching effect on the substrate.

The criteria for selecting the M loss spectrum to be measured are as follows:
There are no other discrete spectra in its vicinity. If such spectra exist, there is a high probability that both spectra will overlap and be introduced into the interferometry spectrometer, which may reduce measurement accuracy.

〔Example〕

FIG. 4 shows a case where the method of the present invention is applied to an etching apparatus. In the etching apparatus 10, a substrate 12 such as aluminum to be etched is placed on one electrode plate 11, and an inert gas such as argon gas is introduced between it and the other electrode plate 13. Electrode plate 11.13
This generates argon gas plasma by applying a high-frequency voltage to the substrate 1.
2, the surface of the substrate 12 is scraped off along lines that have been previously patterned on the surface, thereby obtaining a desired image. In this case, a specific wavelength range in the spectrum emitted from atoms or molecules of argon gas is extracted in the same manner as in the case of the sputtering device described above and introduced into a Fabry-Perot interferometry spectrometer (not shown). , produce interference fringes and measure the velocity of atoms or molecules of the inert gas. It is clear that the degree and speed of etching directly correspond to the energy possessed by these gas atoms or molecules in an excited state, so it is possible to feed this back to the etching equipment and control the process to the optimum state at all times. It is.

〔Effect of the invention〕

As detailed above, the present invention selects light in a specific wavelength range from the light spectrum emitted from atoms or molecules in a plasma state, and introduces it into a Fabry-Perot interferometry spectrometer.
By analyzing the interference fringes of this, the velocity (kinetic energy) of atoms (molecules) in an excited state can be measured, and based on this, the process conditions of sputtering and etching equipment that use plasma can be controlled. Compared to the conventional method of controlling process conditions, which is equivalent to fumbling around, it is possible to control the process conditions with higher accuracy and excellent reproducibility.

[Brief explanation of the drawing]

Figure 1 is a principle diagram of a sputtering apparatus to which the method of the present invention is applied. Figure 2 is an example of an emission spectrum to which the present invention is applied. Figure 3 is a specific example of a sputtering apparatus to which the method of the present invention is applied. Schematic side view, FIG. 4 is a schematic side view of a specific example of the same etching apparatus. 8~・Etalon plate Schematic side view of a specific example of a sputtering apparatus to which the present invention is applied FIG. 3

Claims (2)

[Claims] (1) In the step of forming or etching a metal thin film on the substrate (2, 11) using plasma,
Discrete spectra in specific wavelength ranges of the emission spectra of thin film forming atoms, gas molecules, and/or atoms in plasma are introduced into a Fabry-Perot interferometry spectrometer (7), and their ultrafine structure is analyzed and dealt with. A method characterized by measuring the speed of atoms or molecules in an excited state and feeding this back to the process to control process conditions. (2) The method according to claim 1, wherein the discrete spectrum in the specific wavelength range is selected such that there is no other discrete spectrum that overlaps with the discrete spectrum in the vicinity of the specific wavelength range.