JPH02246328A - Thin film forming and etching equipment - Google Patents

Abstract

PURPOSE:To control the power of a sputtering power supply, the current flowing through an electromagnet, the sputtering gas pressure, the kind of gas, and the mixing ratio of gas by a method wherein fluorescence radiated from atom by using laser fluorescence method is measured by Fabry-Perot interferometers arranged in three directions. CONSTITUTION:Laser rays 11 are introduced into a vacuum vessel; atom or molecule in plasma or the vacuum vessel is irradiated with the rays; electron in particle is transferred to a higher energy level, and made to absorb the laser rays. After that, fluorescence is radiated when electron transfers from the above excited state to a lower energy level state; the radiated fluorescence is measured by Fabry-Perot interferometers 1b, 1c installed in three perpendicular directions, and the velocity distribution of atom or molecule existing in plasma is measured. Thereby, film formation, etching power, current flowing through an electromagnet for magnetic control, gas pressure at the time of film formation or etching, kind of gas, and gas mixing ratio are controlled, and manufacturing and etching conditions of a film formed on a substrate are adjusted.

Description

[Detailed Description of the Invention] [Summary] Regarding thin film forming or etching equipment using plasma, it is important to know whether a thin film with optimal film properties and uniformity can be stably obtained.
Alternatively, the purpose of the present invention is to provide a thin film forming apparatus and an etching apparatus equipped with a feedback mechanism so that a uniform etching operation is performed in an extremely stable state. A laser beam with energy matching the energy level difference of the electrons of atoms or molecules is introduced into the vacuum chamber, and the atoms or molecules existing in the plasma or vacuum chamber are irradiated to raise the electrons in the particles to a higher level. The laser beam is absorbed by the transition to a lower energy level, and then the fluorescence (LIF) generated when this excited state transitions to a lower energy state is measured using a Fabry Bellow interferometer spectrometer installed in three orthogonal directions. The velocity distribution of atoms or molecules existing in the plasma is measured, and based on the measurement results, ■ film formation or etching power, ■ current flowing through the electromagnet for controlling the magnetic field generated on the target surface, ■ film formation or etching time. gas pressure,■
The configuration is such that one or more of the types of gases and their mixing ratios are controlled during film formation or etching, and the conditions for forming or etching the film formed on the substrate are adjusted.

[Industrial Application Field] The present invention relates to a thin film forming or etching apparatus using plasma.

[Prior Art] In a conventional thin film forming apparatus, especially a thin film forming apparatus using plasma (sputtering, ion blating, plasma CVD), a thin film formed on a substrate is usually
It was controlled by changing the following: (1) device output (power), (2) substrate temperature, (2) pressure of gas (for example, Ar, Ox, SiH4, etc.) introduced into the vacuum chamber during film formation. The same thing happened with etching equipment using plasma. By adjusting these three main operating conditions, it is possible to form a generally desired thin film, but it is important to eliminate variations in film orientation and microstructure, which have a large effect on the magnetic and mechanical properties of JII, and to achieve a stable thin film. has not yet been formed.

In addition, when scaling up the device, even if the operating conditions are set to be the same as those obtained in the experimental stage, the reproducibility of the thin film formed is insufficient, and in some cases, the formation conditions may be completely different. . Such problems are not limited to thin film forming apparatuses, but also apply to etching apparatuses using plasma, and a similar solution is desired.

[Problems to be Solved by the Invention] In order to solve Tsuchiura's problem, measurement of the plasma itself during sputtering during thin film formation1, for example,
Attempts are being made to measure the plasma temperature, electron temperature, electron density, etc. of the plasma, and observe the spectrum generated from the plasma through spectroscopic analysis, and to control thin film formation based on these measured or observed results. .

However, even if these methods are used to control thin film formation, the relationship between the physical properties of the formed film and the above-mentioned measured or observed results is not clear, and it is insufficient to control the film formation conditions. Ta.

In view of these circumstances, an object of the present invention is to stably obtain yiB with optimal and uniform film properties, or to
It is an object of the present invention to provide a thin film forming apparatus and an etching apparatus equipped with a feedback mechanism so that a uniform etching operation can be performed in an extremely stable state.

[Means for Solving the Problems] In order to solve these problems, the present invention provides a thin film forming apparatus that uses plasma to form a thin film on a substrate. Laser light is used as a light with extremely good properties, and the laser light has an energy that matches the energy level difference of the electrons in the particles in the atomic or molecular state existing in the plasma or vacuum chamber. The laser beam is applied to atoms and molecules existing in plasma or a vacuum chamber, and the electrons in the particles are moved to a higher level, thereby absorbing the laser beam and transitioning to an excited state. The atom or molecule excited to this excited state then generates fluorescence when it transitions the electrons at the excited level within the particle to a lower energy state. This fluorescent light is L
I F (La5erlad++ced Flooror
csceoce).

When a particle is in motion, the wavelength (ie, energy) of the incident laser light seen by the particle differs due to the Doppler effect. Therefore, depending on the speed of the particle, the energy of the laser beam that matches the energy level difference of the electrons within the particle will differ.

The particle now at rest has a frequency ν. The particle absorbs the laser beam, and the energy of this laser beam is equal to the unit energy difference of the electrons within the particle.
Next, assume that fluorescent light is emitted ((a) in Figure 3).

At this time, the wavelength λ of the light and the energy level difference E of the electrons within the particle are E = h shi, = h − ・ ・ ・ ・ ・ (2) λ
.

However, C: speed of light (3×10'@/g) is given by h Niblank constant.

When the particle is moving toward the light at a velocity v (a/s) (FIG. 3(b)), the wavelength of the light seen from the particle shifts to the shorter wavelength side due to the Doppler effect. The wavelength λ■ seen from the particle at this time is given by. Therefore, the energy of light differs from the level difference E (-hν,) of the electron energy of the particle.

As a result, no light absorption occurs and no fluorescence occurs.

At this time, if the wavelength (frequency) of the light can be changed, it is possible to make the energy equal to the level difference of the electron energy of the particle even for a particle with a velocity of ■. To do this, let the changed frequency of the light be ν", and by changing the frequency to the new one given by equation (5), it becomes possible to generate fluorescence for particles with a velocity of ■. Laser fluorescence is a method of determining particle velocity using laser light with a variable frequency.

We will explain how to obtain the three-dimensional velocity vector of a particle using laser fluorescence. Take the rectangular coordinates x, y, z (Figure 2) at the location where you want to measure the velocity of the particle, and place the detectors at equal distances apart in three directions.

In addition, in the figure, 11 is a laser beam, 12 is a target, 1
3 points to the substrate. Letting the velocity vector of one particle be V, γ
The direction cosine of the vector expressed in polar coordinates of , θ, φ is (siaθcotφ, sieθsiaφ, cosθ
)−(6). Also, let the direction cosine of the incident laser beam be (α, β, γ). At this time, if the angle between the particle's velocity vector ■ and the incident laser beam is ψ, then cosψ
= a sinθcosφ+βsinθsinφ+7c
osO... (7) It is given by:

The frequency of the incident laser beam absorbed by the particles is calculated as in equation (5) = v, (1+ - (αsiaθcosφC +βsinθsinφ+7 cosθ)i ・ (8)
However, the velocity components of the particle in the three directions of particle observation direction X + 3' and z are: ν″1=ν (1+ −) ・ ・ ・ ・ (10) =v, (1+ −(czsioθcosφ+βsiaθ
sinφ+7 cosθ)) (1+ vsioθsinφ ・ ・ ・ ・ (12) =v, (1+ −(α5llecosφ+βsla θ
It is given by si Ilφ+7 cow θ) ) 1vcosθ +□).

・ ・ ・ ・ (13); ν, (1+−(αsinθcosφ + β peak θ peak φ+γcosθ)) (1 "Ioooo"6) + ・ ・ ・ ・ (11) Therefore, ν°°3. By measuring ν"2.I3, V, θ, and φ can be determined, and the particle velocity vector ■ is determined. Based on this measurement result, a feedback mechanism that changes the plasma conditions allows the , ■ current flowing through the magnetic field control magnet generated on the target surface, ■ gas pressure during sputtering, ■ type of gas during sputtering and its mixing ratio, and controlling at least one of the following film forming conditions to form a film on the substrate. ruffj
This is to adjust the 1rli physical properties of li to yA.

1)'K * し°1. A Fapry Bellow interferometry spectrometer is used to measure SI1. The principles of the Fapry-Bello interferometry are discussed, for example, by Max Horn, Emil
The deviation of the 0 frequency described in "Principles of Optics" by Tsuolff (translated by Kou Kusayo, Hidetsugu Yokota, Tokai University Press) can be measured from the deviation of the interference peak position.

Furthermore, if the measuring direction is placed in a plane perpendicular to the incident laser beam, light with a frequency of ν'' will enter the detector (since U=O in this case).

By changing the frequency of the incident laser beam of the particle velocity based on the deviation of this ν'' from ν, it is possible to measure the velocity distribution of the particles in the direction of the incident laser beam.

As the feedback parameter for changing the plasma conditions in this way, any of the particle velocity vector, each velocity component, or the velocity component in the direction of the incident laser beam may be used as described above.

Furthermore, in an etching apparatus that etches a substrate using plasma, the same <LIF can be used to set either the particle velocity vector size or each velocity component, or the velocity component in the direction of the incident laser beam as the feedback parameter. A feedback mechanism is provided to measure and change the etching conditions based on the measurement results, and this feedback mechanism controls: ■ the etching power output, ■ the current flowing to the electromagnet for controlling the magnetic field generated to increase ionization, and ■ the etching conditions during etching. The etching condition of the substrate is adjusted by controlling at least one etching condition of the gas pressure, the type of gas during Φ etching, and the mixing ratio thereof.

[Example] An example of the present invention is shown in FIG. FIG. 1 shows a schematic plan view of an I film forming apparatus according to an embodiment of the present invention, in which Fe was used as a target. An excimer laser-excited dye laser was used as the laser light source 1o.

Make it incident at a certain angle from the vertical direction. Observation of fluorescence is carried out in the directions of three axes orthogonal to each other, and Fabry-Herot interferometry spectrometers 1a, lb, and lc are placed respectively. A Fabry-Perot interferometer 3 is shown as a detector in the X direction. This interferometer 3 and lens 2a
The Fabry-Perot interferometry spectrometer 1a, which is optically connected via Light is efficiently extracted in the form of interference fringes through the lens 2b. N2 gas is introduced into the Fabry-Perot interferometer 1a, and its pressure is detected by the pressure sensor 5.

Sputtering is carried out between Targetera I/12 and substrate 13.
An inert gas such as R is introduced, and during this time, a high voltage is applied from the DC or nF power source 14 to form a plasma, and the positive ions of the inert gas generated in the plasma collide with the target 12 and are knocked out from the target. This is for depositing the ejected target atoms onto the substrate 13.

A support part 14 that supports the target 12 from the back side houses an electromagnet 15 for magnetron sputtering in an inner space. Winding 16 of electromagnet 15 is connected to a current controller 17, which controls the strength of the magnetic field based on Fe particle velocity measurements, as described in more detail below. The end of the support part 14 becomes an introduction hole for the winding 16,
In addition, target 1 is heated by collision with argon atoms.
This serves as a flow path for cooling water that cools the 2. A sheath body 18 surrounding the outside of the support part 14 is provided in close contact with the support body 14 via a circle ring 19 and directly in close contact with the plasma chamber wall. In addition, the sheath body 18 and the support body 1 are
An insulating glass 20 is provided between the two.

In this embodiment, Fe is used as the target 12, and the velocity distribution of Fe atoms ejected from the target is measured. The direction of incidence of the laser beam 11 is not limited to the direction shown in the figure, and it can be brought closer to the substrate 13 so as to measure the velocity of Fe atoms just before being deposited on the substrate 13. Further, although an example of FeN atoms will be described below, the velocity distribution of atoms can be similarly measured for sputtering of other atoms. Furthermore, when sputtering molecules, if the energy level of the molecule is known, measurement becomes possible in the same way.

In order to irradiate a Fe atom with laser light, cause it to absorb it, and then generate fluorescence, it is necessary to tune the energy (wavelength) of the laser light so that it is equal to the energy level difference of the electrons within the Fe atom. There is. Figure 4 shows Fe
In the diagram showing the energy levels of electrons of atoms, a'D4 is the ground state and y'D,' and a'F are the excited states. Figure 4 shows that the electrons in the ground plane Ra'Da have a wavelength of 302.
064 nm laser light is absorbed to form an excited state B y '
Da.

It is shown that it is excited by , and then it emits light with a wavelength of 382.043 nm and transitions to the Ra' F s state.

Therefore, it is possible to measure the velocity by tuning the incident laser wavelength to near the wavelength of 302.062 nm that excites the ground state a'Da, scanning the laser wavelength, and observing the fluorescence generated at that time. .

As shown in Figure 5, when a group of particles at point 0 is irradiated with a laser with a frequency of ν'', the laser light is absorbed by particles with a velocity component of v cos ψ (ψ is the velocity vector of the particle). is the angle formed by the incident laser beam),
Therefore, absorption occurs in particles that are emitted from the zero point shown in FIG. 5 and have a velocity that reaches the bottom surface cb of the cone C whose bottom surface is as large as possible. Fluorescent light is then emitted from these particles and measured in the form of wavelength distribution in each direction by Fabry-Perot interferometry spectrometers placed on the x, y, and z axes. Changing the frequency ν'' of the incident laser beam corresponds to moving the position of the bottom of the cone with the laser beam as its axis (see equation (8)), so changing the frequency of the laser beam during sputtering If measurement is carried out while changing the direction of the laser beam, and the fluorescence intensity is measured by placing the potuminal in a direction perpendicular to the laser beam at point 0, it is possible to measure the velocity distribution of particles in the laser direction at point 0.

The measurement parameters related to the velocity of particles measured in this way are one of the major factors that govern the characteristics of the film deposited on the substrate, and by feeding back the measurement results to the film fabrication conditions, it is possible to improve the physical properties of the film. Control becomes possible.

Figure 1 shows the feedback method. Feedback methods include RF or DC power source 13.
and a current controller (not shown), a current controller 17 for a magnetic field generating electromagnet provided on the back side of the target 12
There is a method of feeding back to one or more types of gas flow controllers via the personal computer 21.

Reference numeral 22 denotes a recorder which records momentary atomic velocity, current, pressure, etc., and is useful as information for the operator to input commands to change the current, pressure, etc. into the terminal of the personal computer 21 if necessary.

The sixth factor shows the current-voltage characteristics of various sputtering methods. The current flowing through the target and the voltage applied to the target at that time are not independent parameters, but are in a relationship such that if one is determined, the other is determined accordingly.

In Figure 6, the RF 2 poles and DC 2 poles correspond to the case where the current flowing through the electromagnet in Figure 1 is zero (zero horizontal magnetic field generated on the target surface), and the planar magnetron corresponds to the case in Figure 3. This corresponds to when a current is passed through an electromagnet.

In the case of a planar magnetron, even if power is applied to the target from the outside, the voltage applied to the target remains the same, only the current flowing through the target changes. The value of the magnetic field at this time is approximately 5000 on the target surface.
is the value of e.

In this way, depending on the value of the magnetic field generated on the target surface, I
-V characteristics change.

The voltage applied to the target determines the energy when the ionized inert gas hits the target, and is one of the factors that determines the speed, or energy, of the target atoms flying out from the target. Therefore R.F.
Alternatively, it is possible to change the energy of the target atoms coming out of the target by changing the DC power supply and the current flowing through the electromagnet installed at the bottom of the target, which also determines the energy of the target atoms flowing into the substrate. This is one of the major factors.

The pressure of the inert gas inserted into the vacuum pelger in the sputtering apparatus determines the number of collisions of target atoms ejected from the target.

The mean free path (that is, the probability of collision with the discharge gas) of the sputtered particles is given by (``Thin Film Technology'' written by Shigeru Tanyo and Kiyoshi Kazusa, Kyoritsu Shuppan).

here, r1 radius of varnished atom r2: Radius of atoms of discharge gas r,: density of discharge gas It is.

Now, when Fe atoms are sputtered with Ar gas.

When the pressure of Ar gas is 10”-2 Torr, r, x
i, 24X10-"cm r2 depth 1.91X10-@cm = 3.5X10"/cm' So, by substituting it into the above equation, we get λ = 0.92cm, and when the pressure of Ar gas is 5x10 Torr, n *=1.75X101'/cm', so λ-depth is 1.83cm.

Therefore, in the case of sputtering, the distance between electrodes (distance between target and substrate) is usually 5 to 10 cm.
The atoms ejected from the target due to the pressure of the Ar gas will collide with the inserted Ar gas about 10 times or less. As the pressure of the inserted Ar gas decreases, the number of collisions decreases.

The sputtered atoms that fly out from the target after being sputtered lose energy due to collision with the inserted gas, and the energy of the sputtered atoms flowing into the substrate changes. According to the method of the present invention, the sputtered atoms are The energy of the target atoms flowing into the substrate can be changed by performing feedback control based on the velocity of the target atoms after colliding with the substrate, adjusting the flow rate of the inserted gas, and controlling the pressure of the inserted gas inside the Pelger. Naturally, it is also possible to change the mean free path of sputtered particles by changing the type of inserted gas or by mixing one type of gas with several other types of gas. FIG. 1 shows the case of two types of gases 22a and 22b. The gas to be mixed must be a gas that does not affect the film quality, and inert gases He, Ne, Ar, Kr, and Xe are most commonly used. Non-inert gases such as H2 and N2.02 can be mixed as long as they do not affect the membrane.

As described above, the pressure, type, and mixing ratio of the inserted gas are one of the major factors that determine the energy of target atoms flowing into the substrate.

As mentioned above, the methods of controlling the energy of sputtered atoms incident on the substrate include: ■ Voltage and current (power) of the RF or DC power supply ■ Current for the electromagnet that controls the magnetic field generated on the target surface ■ Gas pressure during sputtering ■ Type of gas during sputtering ■ Mixing ratio of different gases during sputtering, etc. The value of the energy incident on the substrate measured by the Fabry-Perot interferometer is fed back to one or more of the controllers listed in ■ to ■ above. This makes it possible to obtain optimal film formation conditions. It will be easily understood that in the case of etching, feedback can be performed in the same manner as in the above-mentioned method.

[Effects of the Invention] As described above, the present invention uses laser fluorescence to measure fluorescence emitted from atoms with a Fabry-Perot interferometry spectrometer installed in three directions, thereby detecting the presence of light in a plasma or in a vacuum chamber. The claim is made because it is configured to measure the velocity distribution of existing atoms and molecules and control the power (voltage and current) of the sputtering power source, the current flowing to the electromagnet, the sputtering gas pressure, the type of gas used during sputtering, and its mixing ratio. According to the invention set forth in claim 1, a good film with constant physical properties can be obtained, and with the invention set forth in claim 3, a good film with constant etching depth, shape, etc. can be obtained.

Furthermore, the same effect can be achieved by the invention according to claim 2.4, in which a light intensity detector is provided in a direction orthogonal to the laser beam.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a sputtering apparatus according to the present invention, and FIG. 2 is a schematic diagram showing particles moving from a target toward a substrate and the direction of laser light irradiated onto the particles. Figure 3 is a schematic diagram showing the laser beam irradiation on moving particles and stationary particles, Figure 4 is the energy level diagram of iron electrons, and Figure 5 is the velocity vector of the particle where the laser beam is absorbed. The schematic diagram shown in FIG. 6 is a graph showing current-voltage characteristics of various sputtering methods. 1-Fabry-Perot interferometry spectrometer, 2.3-lens, 10
- Laser light source, 12 - Target, 13 - Substrate Patent applicant Fujitsu Ltd. Boyuko's 2 degrees to 7 torr Figure 5 Ray dimensions' - Bald. Takeko cm/s, )/. Resting diagram Energy of Fe electron - Quasi-A diagram 4

Claims (1)

[Claims] 1. A thin film forming apparatus that applies a voltage between a target and a substrate placed opposite each other in a vacuum chamber, generates plasma in the chamber, and forms a thin film on the substrate using the plasma. , A laser beam with an energy matching the energy level difference of the electrons of atoms or molecules of the thin film-forming particles moving toward the substrate is introduced into the vacuum chamber, and the atoms existing in the plasma or vacuum chamber are Alternatively, the laser light is absorbed by irradiating molecules and moving the electrons within the particles to a higher level, and then the fluorescence (LIF) generated when the excited state transitions to a lower energy state is transmitted in three orthogonal directions. The velocity distribution of atoms or molecules present in the plasma is measured by the Fabry-Perot interferometry spectrometer provided, and based on the measurement results, (1) film formation power,
(2) Current flowing through the electromagnet for magnetic field control generated on the target surface, (3) Gas pressure during film formation, (4
) A thin film forming apparatus characterized by controlling one or some of the types of gases and their mixing ratios during film formation to adjust the conditions for forming a film formed on a substrate. 2. In the thin film forming apparatus according to claim 1, a detector capable of measuring light intensity in a direction perpendicular to the direction of the laser introduced into the vacuum chamber is provided, and the Fabry-Perot interference is detected in two directions perpendicular to the direction. Two spectrometers were installed, and based on the measurement results of these detectors and spectrometers, the above (1) and (2)
2. The thin film forming apparatus according to claim 1, wherein one or more of (3) and (4) are controlled. 3. In an etching apparatus that generates plasma in a vacuum chamber and uses the plasma to etch a substrate, the energy level difference of the electrons of the atoms or molecules of the etching particles moving toward the substrate matches the energy level difference. Introducing an energetic laser beam into a vacuum chamber, irradiating the atoms or molecules present in the plasma or vacuum chamber, and absorbing the laser beam by moving the electrons within the particles to a higher level. The fluorescence (LIF) generated when transitioning from this excited state to a lower energy state is
The velocity distribution of atoms or molecules present in the plasma is measured by measuring with a Fabry-Perot interferometry spectrometer installed in the direction, and based on the measurement results, (1) etching particle formation power, (2) plasma ionization Current flowing through the magnetic field control electromagnet to increase the
An etching apparatus characterized by adjusting etching conditions for a substrate by controlling one or more of (3) gas pressure during etching, and (4) types of etching gases and their mixing ratios. 4. In the etching apparatus according to claim 3, a detector capable of measuring the light intensity in a direction perpendicular to the direction of the laser introduced into the vacuum chamber is provided, and the Fabry-Perot interference spectroscopy is performed in two directions perpendicular to the direction. Two detectors were installed, and based on the measurement results of these detectors and spectrometers, the above (1) and (2)
4. The etching apparatus according to claim 3, wherein one or more of (3), (3), and (4) are controlled.