JPH0979808A - Film thickness measuring method and device to practice this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor and measure its film thickness while forming a thin film with simple and inexpensice conifguration by arranging an electric resistance being a fiber-shaped sensor on an upper surface of a substrate on which the thin film is formed. SOLUTION: A fiber shaped sensor (an electric resistance) 1 whose resistance value is premeasured is arranged on an upper surface of a substrate 2 on which a thin film 21 is formed. When the resistance value (an electric resistance rate) of this sensor 1 is selected, a resistance value to a film thickness can be changed. That is, sensitivity of a measuring area is changed by selecting a resistance value of the sensor 1 close to the film thiskness wanted to be measured, and a more accurate film thickness can be monitored and measured. The sensor 1 is thin, and since influence on the substrate 2 can be ignored, influence on film forming particles is reduced, and a film thickness can be monitored and measured under a spatially and positionally equal condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film thickness measuring method and an apparatus for carrying out the method, and more particularly to a film thickness measuring method and a method for monitoring and measuring the film thickness while forming a thin film. It relates to a device to be implemented.

[0002]

2. Description of the Related Art A conventional example will be described with reference to the drawings. A crystal oscillator method, which is a typical conventional example of a film thickness measuring method for measuring while monitoring the film thickness being formed, will be described. When a film is formed on a crystal oscillator having a high Q, the plate thickness of the crystal oscillator changes equivalently, and the oscillation frequency of the oscillator using the crystal oscillator decreases. The relationship between the decrease in the oscillation frequency of this oscillator and the film thickness formed on the crystal oscillator was measured in advance, and the film thickness was formed corresponding to the decrease in the oscillation frequency of the oscillator during the actual film formation. It is the film thickness.

The quartz crystal oscillator method allows the mass film thickness to be monitored during film formation and allows the detector head to be easily attached to the substrate on which the thin film is to be formed through a standard feedthrough. It can be said that this is the most standard film thickness measurement method. However, since the film thickness attached to the crystal unit is measured, it is necessary to calibrate the film thickness of the film formed after attachment by comparing it with the film thickness measured by another method. Since the detector head that houses the crystal unit has a size of several centimeters, when it is placed on the upper part of the substrate on which the film is to be formed, the shadow of the detector head seen from the evaporation source of the thin film substance is A part is formed on the substrate. Therefore, the detector head cannot be installed on the upper part of the substrate, and the detector head must be installed on the side of the substrate or other places other than the upper part of the substrate. Placing the detector head on a place other than the upper part of the substrate means that the detector head is installed spatially separated from the place where the thin film is formed on the substrate. The measured film thickness and the film thickness formed on the substrate inevitably show different values. Further, although it depends on the spatial shape of the flying film-forming substance, the influence on the film thickness distribution in the measurement region cannot be ignored. Therefore, the calibrated film thickness is referred to and the measurement is performed as an empirical value that depends on the position of the detector head. Further, the large size of the detector head makes the crystal oscillator method unsuitable for monitoring when forming a film in a minute region.

An ellipsometric method using an ellipsometer is also employed as a film thickness measuring method for measuring while monitoring the film thickness being formed. In this polarization analysis, light is incident on the thin film, the polarization of the reflected light is measured to measure the refractive index n and the absorption coefficient k, and these measured values are arithmetically processed to obtain the film thickness. As described above, this measurement method has a refractive index n
In this method, the film thickness is measured based on the absorption coefficient k, and the refractive index n and the absorption coefficient k are usually unknown in actual thin film production, and it is difficult to obtain an accurate film thickness. . By the way, when measuring the film thickness of a substance such as a metal having a large absorption coefficient k, it is only possible to measure the thin film thickness because the absorption of light is large. In general, a computer is required for the calculation and analysis process of the measured value, and the measuring device becomes large in size and expensive.

[0005]

SUMMARY OF THE INVENTION The present invention provides a film thickness measuring method and an apparatus for carrying out the method, which solves the above problems.

[0006]

Means for Solving the Problems A film thickness measuring method for measuring an electric resistance 1 which changes when film-forming particles fly and are laminated in a thin film is constituted. And the electric resistance 1 constituted the film thickness measuring method which is a fibrous sensor. Also,
A film thickness measuring method was constructed in which the electric resistance 1 was placed on the upper surface of the substrate 2 on which the thin film 21 was to be formed.

Further, a film thickness measuring method for measuring the electric resistance of the electric resistance 1 by appropriately changing the electric resistance was constructed. When the electric resistivity is changed appropriately, the electric resistance 1 is changed to Pt, N
The film thickness measuring method was set to i or Cu. Here, the film thickness measuring apparatus including the electric resistance 1 installed near the substrate 2 on which the thin film 21 is to be formed and the electric resistance measuring device 3 for measuring the electric resistance is configured.

The electric resistance 1 constitutes a film thickness measuring device which is a fibrous sensor. In addition, the film thickness measuring device is configured such that the electric resistance of the electric resistance 1 is larger than that of the thin film 21 to be formed. Further, the electric resistance 1 constitutes a film thickness measuring device whose electric resistance is Pt, Ni or Cu.

Further, the electric resistance 1 constitutes a film thickness measuring device made of an insulating material.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The film thickness measuring method of the present invention and the apparatus for carrying out this method are formed by laminating a thin film substance on a fiber-like sensor and measuring the overall electric resistance. The thickness of the formed film is obtained by conversion. When forming a film, a fibrous material having a higher electrical resistivity than the film forming substance on the upper surface of the substrate on which the film is to be formed,
A rod-shaped material is installed and the electrical resistance is measured. When film-forming particles fly onto this fibrous or rod-shaped substance and are laminated in a thin film form, the overall electric resistance changes. Therefore, the film thickness can be indirectly obtained by measuring the electric resistivity.

As a sensor, a small fibrous shape is formed on the upper surface of the substrate,
Since the film thickness can be measured by installing a rod-shaped substance, the film thickness of the thin film is small because the shadowed area on the substrate is small when viewed from the evaporation source of the substance to be formed during film formation. The influence on the distribution is small. Since the film thickness can be measured only by measuring the electric resistance, the film thickness measuring device can be a simpler and less expensive device than the conventional film thickness measuring device.

The sensor can be made of any material as long as its electrical resistivity is higher than that of the film forming material. The ellipsometry is not good at measuring the film thickness of a thin film having a large absorption coefficient k such as a metal material, but the film thickness measuring method of the present invention can easily carry out this. The film thickness measuring method of the present invention can measure the film thickness anywhere in vacuum or in a gas atmosphere.

[0013]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a fiber-shaped sensor used in the present invention. This fibrous sensor 1 is a fibrous sensor having a diameter: a, a cross-sectional area: S ₁ , and a length: L, and is attached to a substrate 2 on which a thin film 21 is to be formed. In this case, the resistance value R ₁ of the fibrous sensor ₁ is measured in advance.

FIG. 2 shows a thin film 1 on the upper surface of the fibrous sensor.
It is a figure which shows the place where 3 was formed. The film-forming particles fly from above the fibrous sensor, and the thin film 13 is formed on the upper surface of the fibrous sensor 1 relatively thickly. Resistance R ₂ of the thin film 13, the thin film 13 the cross-sectional area S _2, when the electrical resistivity [rho _2, can be expressed as follows. R ₂ = ρ ₂ (L / S ₂ ) (1) Here, if a conductive substance is deposited on the fibrous sensor, the resistance R of the entire sensor changes. At this time, the total resistance R is R = R ₁ · R ₂ / (R ₁ + R ₂ ) (2). When R ₂ is calculated, R ₂ = R · R ₁ / (R ₁ −R) (3), and the cross-sectional area S ₂ of the thin film 13 is S ₂ = ρ ₂ · L (R ₁ −R) / (R · R ₁ ) Given in (4).

Since S ₂ = a · d, the film thickness d
Is d = {(ρ ₂ · L (R ₁ −R) / (R · R ₁ )} / a (5) and the film thickness can be simply obtained. : 1 cm, resistivity R1: 10 ⁹ Ω ・
Pt, N when using a cm-shaped fiber sensor
It is a figure which shows the change of the resistance value with respect to the film thickness of the thin film of i, Cu.

Referring to FIG. 4, there is shown a change in resistance value with respect to the film thickness of the Pt, Ni, Cu thin film 21 when a fiber-like sensor made of glass having a diameter a of 1 μm and a length L of 1 cm is used. It is a figure. When an insulating material which is an infinite resistance material of the fibrous sensor 1, for example, glass is used, d = ρ ₂ · L / (a · R) (6) is obtained from the equation (1).

By selecting the resistance value of the fibrous sensor 1 in FIGS. 3 and 4, the amount of change in the resistance value with respect to the film thickness can be changed. That is, the sensitivity of the measurement region can be changed by selecting the resistance value of the sensor in the vicinity of the film thickness to be measured, and more accurate film thickness monitoring and measurement can be performed. However, in the case of actual film formation, the film formation particles do not always come in from only one direction, and the spatial distribution of the arrival particles is different due to the difference in the film formation method, so the area and distribution formed on the sensor are different. .
Therefore, the resistivity after film formation is measured, the film thickness on the substrate at that time is measured by another measuring method, and the film thickness is calibrated, whereby empirically accurate film thickness monitoring and measurement can be performed.

FIG. 5 is a view showing a fiber sensor installed on a substrate. Fiber sensor 1
If the sensor is thin and its effect on the substrate can be neglected, the sensor can be installed directly on the substrate as shown in FIG. Since this has little influence on the film-forming particles, the film thickness monitor and measurement can be performed under the same conditions spatially and positionally. Therefore, it is possible to monitor and measure the film thickness which is almost equal to the film thickness of the thin film 21 on the substrate.

[0019]

As described above, according to the present invention, it is possible to measure the electric resistance of the fibrous sensor while monitoring the film thickness of the thin film being formed. . Therefore, this film thickness measuring device measures the refractive index n and the absorption coefficient k of the film thickness, and compares the measured value with a complicated calculation analysis process using a large computer to measure the film thickness. Then, it can be made extremely simple and inexpensive.

The sensor is composed of a fiber-shaped sensor, and by forming this into a fiber or rod shape, the shape of the sensor can be made small and thin. In this case, even if it is placed in direct contact with the upper surface of the substrate, the influence on the film-forming particles is extremely small, and the film thickness can be monitored and measured under the same spatial and positional conditions. Therefore, it is possible to monitor and measure the film thickness which is almost equal to the film thickness of the thin film on the substrate.

Further, it is possible to monitor and measure the film thickness of a substance having an electric resistivity smaller than that of the fibrous sensor. Therefore, it is possible to monitor and measure the thickness of a thin film such as a metal film which is not good at ellipsometry. Even if the resistivity of the formed thin film substance is unknown, conversely, the electrical resistivity can be obtained from the film thickness by calculating the film thickness by another film thickness measuring method and performing comparative calibration. It can be used empirically to monitor and measure film thickness. Therefore, with respect to the structure of the thin film substance, although the unknown constant, for example, the electrical resistivity is different due to the difference in the crystal structure, the mixed crystal and the like, this can also be accurately measured by performing the calibration.

[Brief description of drawings]

FIG. 1 is a diagram showing a fiber-shaped sensor used in the present invention.

FIG. 2 is a diagram showing a thin film formed on the upper surface of the sensor.

FIG. 3 Diameter a: 1 μm, Length L: 1 cm, Resistivity R
_The figure which shows the change of the resistance value with respect to the film thickness of the thin film of Pt, Ni, Cu when using a fiber-shaped sensor of 1:10 < ⁹ > (ohm) * cm.

FIG. 4 shows Pt and N when using a fiber-like sensor made of glass having a diameter a of 1 μm and length L of 1 cm.
The figure which shows the change of the resistance value with respect to the film thickness of the thin film of i, Cu.

FIG. 5 is a view showing a fiber sensor installed on a substrate.

[Explanation of symbols]

 1 electrical resistance 13 thin film 2 substrate 21 thin film 3 electrical resistance measuring instrument

Claims (10)

[Claims] 1. A film thickness measuring method for measuring an electrical resistance which changes when film-forming particles fly and are laminated in a thin film form. 2. The film thickness measuring method according to claim 1, wherein the electric resistance is a fibrous sensor. 3. The film thickness measuring method according to claim 1, wherein the electric resistance is set on the upper surface of the substrate on which the thin film is to be formed. . 4. The film thickness measuring method according to any one of claims 1 to 3, wherein the electric resistivity of electric resistance is appropriately changed and measured. . 5. The film thickness measuring method according to claim 4, wherein the electric resistance is Pt, Ni or Cu. 6. A film thickness measuring apparatus comprising an electric resistance installed near a substrate on which a thin film is to be formed, and an electric resistance measuring device for measuring the electric resistance. 7. The film thickness measuring device according to claim 6, wherein the electric resistance is a fiber sensor. 8. The film thickness measuring device according to claim 6 or 7, wherein the electric resistance of the electric resistance is larger than that of the thin film to be formed. Film thickness measuring device. 9. The film thickness measuring apparatus according to claim 6, wherein the electric resistance is Pt, Ni or Cu. . 10. The film thickness measuring apparatus according to claim 6, wherein the electric resistance is made of an insulating material.