JPH07207440A - Method and device for forming reactive sputtering film - Google Patents

Abstract

PURPOSE:To surely form a film with desired quality at a desired film forming rate by a reactive sputtering method by controlling the sputtering conditions according to the output result from a data processing device which determines functional relations between voltage applied on the sputtering device, electric current and power. CONSTITUTION:A target 1b comprised of Sn, Zn, In, Ti and other metal is mounted on an electrode 1a in a sputtering chamber 1, and a substrate 1d where the film is to be formed is disposed on an electrode 1c facing to the target. The sputtering chamber 1 is evacuated with an evacuating device 5, while the mixture gas of reactive gas such as oxygen and rare gas such as Ar is supplied from a gas introducing device. Voltage is applied between electrodes 1a and 1c from a power source 2 to generate plasma and to form a film of metal oxide or the like produced from the target metal and the reactive gas, on the substrate 1d. In this method, functional relations between at least two among the voltage, current and power applied on the electrodes 1a and 1c are obtd. with a data processing device 4 and controlling signals are sent from the data processing device 4 to the power source 2 and the gas introducing device 3 according to the preliminarily determined conditions to properly control the sputtering conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method by a reactive sputtering method and a film forming apparatus. More specifically, when forming a film, the current-voltage characteristics of plasma are obtained, and the The present invention relates to a method of controlling the quality of a formed film and forming a film at a desired film forming rate.

[0002]

2. Description of the Related Art A reactive gas or a mixed gas of a reactive gas and a noble gas is made to collide with a target to knock out atoms contained in the target, and a process until such atoms are deposited on a substrate and after the deposition, The so-called reactive sputtering method of reacting with a gas has been used as an effective means of forming a compound film.

Conventionally, in order to obtain a film having a desired quality, various factors such as a mixture ratio of sputter gas, an introduced gas flow rate, an applied voltage, an applied current and an applied power are changed in advance to obtain an actual film. The quality of the obtained film is investigated, and when the film is formed later, the film forming reproducibility means that a film of the same quality should be obtained when the film forming conditions are the same. One set of film formation parameters (sputtering gas mixture ratio, total flow rate of introduced gas, applied voltage, applied current, applied power)
The method of forming a film by setting the respective values has been used.

[0004]

However, in the reactive sputtering method, the so-called sputter gas itself, which knocks out atoms from the target, has reactivity, and further ionized ions, and this and the sputter gas Dissociated atoms produced as a result of molecular collisions are also reactive. These reactive gas molecules, dissociated atoms, and ions react with the target surface, the atoms knocked out from the target, the group of such atoms, and the film formed on the substrate. The number, further, the excited state of each particle is a state quantity directly related to the reactivity, these are the electrical resistance of the wall of the container for performing sputtering,
Even a slight change in the impurity gas contained in the sputtering gas, the pumping speed, etc. causes a great change. Due to this change, the reproducibility between the film forming conditions and the film quality is lost.Therefore, when a change occurs, by actually forming the film, the relationship between the two is measured again, The conditions for obtaining the desired film quality had to be recalculated.

Further, in the conventional film formation by the reactive sputtering method, the relationship between the film formation conditions and the quality of the film obtained under the conditions is unstable, and the quality of the obtained film is analyzed. Only by doing so, there was a problem that it was not possible to know whether this relationship was maintained or changed. Further, there is a problem that it is difficult to always obtain a film having the same film quality because a film having different quality is formed each time this relationship is deviated. As a matter of course, each time the relationship is deviated, film formation is performed while changing the film formation conditions, and the quality of the obtained film is analyzed to re-determine the relationship between the film formation condition and the film quality. However, there is also a problem in that a film having a desired quality must be formed on the basis of the conditions.

The present invention has been made in view of the above problems, and an object of the present invention is to form a film between the film forming conditions and a desired film quality before forming the film by the reactive sputtering method. (EN) Provided are a film forming method and a film forming apparatus which can detect a film and correct it when it is misaligned so that a film having a desired quality can be obtained reliably and at a desired film forming rate. is there.

[0007]

In order to achieve the above object, the present invention provides a method for forming a film by a DC sputtering method using a sputtering gas containing a reactive gas, wherein a voltage supplied from a power source to a sputtering apparatus is used. The present invention provides a film forming method characterized by using a data processing device for obtaining a functional relationship between at least two of electric current and electric power, and controlling sputtering conditions based on a processing result of the data processing device. .

The sputter gas is preferably a mixed gas of a reactive gas and a rare gas because it makes the functional relationship characteristic.

According to the present invention, the functional relationship between at least two of the voltage, current and power supplied from the power supply to the electrode of the sputtering apparatus, the mixing ratio of the sputtering gas and the total flow rate of the introduced gas as required. And, based on the obtained functional relationship, grasp the state of the entire reactive sputtering process at that time, and from this, the quality of the obtained film is controlled, and further, at the desired film formation rate. A film can be formed.

In a preferred aspect of the film forming method of the present invention, the mixing ratio of the sputter gas and the total introduced gas flow rate are set so that the functional relationship among the voltage, current and power has a desired relationship. Adjust to control the quality of the resulting film.

In another preferable embodiment of the film forming method of the present invention, the functional relationship among the voltage, the current and the power is measured while keeping the mixing ratio of the sputter gas constant, and the total introduced gas flow rate is determined. By adjusting, the quality of the obtained film and the film forming rate are controlled.

The target used in the present invention is not particularly limited, but a target made of a metal that forms a metal oxide exhibiting conductivity in the state of oxygen deficiency or excess metal is preferable, for example, Sn, In, Z
n, Ti, Th, V, Nb, Ta, Mo, W, Cu, C
Examples thereof include those containing at least one selected from the group consisting of r, Mn, Fe, Ni, Co, Pr, Bi and Nb as a main component.

The present invention also includes a sputtering chamber in which a target and a substrate to be processed are installed, an exhaust device for evacuating the sputtering chamber, and a power supply device for applying a voltage to the electrodes of the sputtering chamber. In a film forming apparatus having a gas introducing device for introducing a sputtering gas composed of a mixed gas of a reactive gas and a rare gas into the sputtering chamber, the film forming device is electrically connected to the power supply device and the gas introducing device, Receiving a data signal from the power supply device and the gas introduction device, the mixing ratio of the sputtering gas, the total flow rate of the introduced gas, the voltage supplied from the power supply device to the electrode of the sputtering chamber,
The present invention provides a film forming apparatus characterized by being provided with a data processing device for obtaining a functional relationship between current and electric power, respectively.

The data processing apparatus is designed so that the power supply apparatus and the gas introduction apparatus can be operated in accordance with preset conditions based on the obtained functional relationship among the sputter gas mixing ratio, the total introduction gas flow rate, the voltage, the current, and the electric power. It is more preferable to have a function of sending a control signal.

It is also preferable to provide a film thickness measuring device near the substrate in the sputtering chamber.

[0016]

In general, in the reactive sputtering method using a highly reactive sputter gas and a target, it is possible to control the voltage supplied from the power source, the current, the power, the mixing ratio of the sputter gas, and the total flow rate of the introduced gas. , The voltage, the electric current, the functional relationship among the power is changed, and further, due to the electric resistance of the wall of the container for sputtering, the impurity gas contained in the sputtering gas, the exhaust gas speed, etc. The functional relationship of changes greatly.

As a result of a detailed examination of the above facts by the present inventors, the reason is not clear, but when the mixing ratio of the sputter gas is kept constant, the curve shape of the functional relationship between the voltage, the current and the power is formed. It has been found that is almost unchanged by the total amount of introduced gas, the electric resistance of the container wall, the impurity gas, the exhaust gas, and other state quantities. Then, it was found that the properties of the obtained film are determined by the positional relationship with the characteristic point such as the inflection point of the current-voltage curve. Furthermore, by changing the total flow rate of the introduced gas while keeping the mixing ratio of the sputtering gas constant, it is possible to change the current value such as the inflection point of the current-voltage curve, or the power value, that is, the film formation rate. It was also found possible.

In the present invention, by utilizing these newly found facts, the properties of the film obtained under a given voltage, current and power are estimated from the shape of the current-voltage curve, and the desired property is obtained. The voltage, current, and power are adjusted to form the film to form the film, or the mixing ratio of the sputtering gas and the total flow rate of the introduced gas are adjusted to change the current-voltage characteristics to the desired values. Then, the film is formed by adjusting the voltage, current, and power so that a film of desired quality can be obtained at a desired film forming rate. Furthermore, by adopting this method, the quality of the obtained film can be estimated and managed with high accuracy without actually checking the quality of the formed film.

[0019]

EXAMPLE FIG. 1 shows a schematic structure of an example of a film forming apparatus of the present invention. In the figure, 1 is a sputtering chamber, and a target 1b electrically connected to one electrode 1a,
Substrate 1d, which is the object to be processed, installed on the other electrode 1c
It has and.

Reference numeral 2 is a power supply device for supplying electric power between the electrodes 1a and 1b, and at least the voltage can be varied, and
It has the function of detecting the voltage, current, and power value in that state.

Reference numeral 3 denotes a gas introduction device, which can change the mixing ratio of the reactive gas and the rare gas and introduce them into the sputtering chamber, and can change the total flow rate of the introduced gas.
It has the function of detecting the mixing ratio of the sputtering gas and the total flow rate of the introduced gas at that time.

Reference numeral 4 is a power supply device 2 and a gas introduction device 3.
A data processing device electrically connected to the power supply device 2 and the gas introduction device 3, and receives a data signal sent from the power supply device 2 and the gas introduction device 3,
It has the function of finding the functional relationship among voltage, current, and power, saving the results, and displaying them on a display or the like. It is further preferable that the data processing device 4 has a function of sending a control signal to the power supply device 2 and the gas introduction device 3 based on the data processing result.

An exhaust device 5 exhausts the interior of the sputtering chamber.

FIG. 2 shows current-voltage characteristics when a tin target is sputtered with a sputtering gas having various mixing ratios of oxygen and argon. Thus, the shape of the current-voltage characteristic changes depending on the mixing ratio of the sputtering gas.

FIG. 3 shows current-voltage characteristics when a tin target is sputtered with a sputtering gas having a mixing ratio of oxygen: argon = 50: 50, in the same manner as above. An oxide film is obtained when formed in the range A on this curve, a partial oxide film is obtained when formed in the range B, and a metal film is obtained when formed in the range C. To be As described above, it is understood that the quality of the obtained film is determined by the positional relationship with the characteristic point such as the inflection point on the curve of the current-voltage characteristic.

In FIG. 3, C having a high film formation rate is used.
The metal film formed in the range of A, the film formation speed is moved to the range of A where the film formation rate is low, and the metal film formed on the substrate is oxidized during this period. It was possible to form a film at a film formation rate higher than that at which the film was continuously formed at one point on the characteristic curve.

FIG. 4 shows current-voltage characteristics when a tin target is sputtered with a sputtering gas having a mixture ratio of oxygen: argon = 50: 50 while changing the total flow rate of the introduced gas. D shows the current-voltage characteristics when the total introduction gas flow rate is 70 sccm, E shows the total introduction gas flow rate of 80 sccm, and F shows the current-voltage characteristics when the total introduction gas flow rate is 90 sccm. As described above, even if the total flow rate of the introduced gas is changed, the curve shape of the current-voltage characteristic hardly changes if the mixing ratio of the sputter gas is the same. It was also found that the shape of this curve does not change due to changes in the amount of state that are difficult to control, such as the electrical resistance of the wall of the container for sputtering, the impurity gas contained in the sputtering gas, and the exhaust rate.

Furthermore, when the total flow rate of the introduced gas is changed without changing the mixed gas ratio of the sputter gas, the curve shape of the power-current characteristics does not change, but a curve with which a film having the same quality can be formed. The current value at the upper point changes. here,
In FIG. 5, the sputtering conditions were the same as those in FIG. 4, and the tin target was sputtered with a mixing ratio of oxygen: argon = 50: 50 and the total flow rate of the introduced gas was changed. The film forming speed is shown. G indicates a total introduction gas flow rate of 70 sccm, H indicates a total introduction gas flow rate of 80 sccm, and I indicates a total introduction gas flow rate of 90 s.
The film forming rate per unit current in the case of ccm is shown. Therefore, it is understood that the film formation rate can be adjusted to a desired value by keeping the mixing ratio of the sputtering gas constant and changing the total flow rate of the introduced gas.

[Embodiment 1] In FIG. 6, width 25 cm, length 56
cm and height of 18 cm, a tin target was attached to the sputter chamber, oxygen gas was introduced at 60 cc / min, and argon gas was introduced at 30 cc / min.
The voltage characteristics are shown. Furthermore, the wavelength 632 of the film formed under the conditions of J, K, and L shown on the curve of the power-voltage characteristic of FIG.
Table 1 shows the refractive index at 0Å. Here, the film formed under the conditions of J and K is an oxide, and the film formed under the condition of L is a partial oxide.

By thus determining the power-voltage characteristics, it is possible to easily control and obtain an oxide film, a partial oxide film, and a metal film, and an oxide film having a different refractive index can also be obtained. You can see that

[Example 2] A tin target was attached to a sputtering chamber having a size of 25 cm in width, 56 cm in length and 18 cm in height, and a mixing ratio of oxygen gas and argon gas was 58: 4.
2 and keep the total introduced gas flow rate at 80cc / min and 110c / min
c, 130 cc. The power-voltage characteristics at this time are as shown in FIGS. 7, 8 and 9, respectively.
Table 2 shows the refractive index at the wavelength 6320Å of the film formed at the points indicated by M, N, and O, which are the same positions on the respective power-voltage characteristic curves. As is clear from this result,
The difference in refractive index was only about 0.2%, and films of almost the same quality could be obtained at different film forming rates.

[Example 3] A sputtering target having a size of 25 cm in width, 56 cm in length, and 18 cm in height was equipped with a tin target, oxygen gas was introduced at 52.2 sccm, and argon gas was introduced at 37.8 sccm to perform sputtering. The power-voltage characteristic at this time is shown in FIG. The tin oxide film formed at points indicated by P, Q, and R on this power-voltage characteristic curve was immersed in a 1N aqueous sodium hydroxide solution at 50 ° C., and the amount of the tin oxide film dissolved away was measured. FIG. 11 shows how the amount of ablated loss changes with time. 11, S is a tin oxide film formed by P on the power-voltage characteristic curve of FIG. 10, T is a tin oxide film formed by Q, and U is a change in the amount of tin oxide formed by R film. Table 3 shows the dissolution rate obtained from FIG. By thus determining the power-voltage characteristics, it is possible to obtain, for example, tin oxide having different durability performance against sodium hydroxide.

[Example 4] A tin target was attached to a sputtering chamber having a size of 25 cm in width, 56 cm in length and 18 cm in height, and a mixing ratio of oxygen gas and argon gas was 50: 5.
0, keep the total introduced gas flow rate at 70cc, 80cc / min,
It was changed to 90cc in 3 ways. The current-voltage characteristics at this time are as shown in D, E, and F of FIG. The electric conductivity of the film formed at several points on the current-voltage characteristic curve is taken as the vertical axis, and the current inflection point at the beginning when the voltage is increased
The difference between the voltage at the shoulder of the voltage curve and the voltage at the time of film formation is plotted on the horizontal axis for each of D, E, and F in FIG.
2, FIG. 13 and FIG. As is clear from this result, it is understood that tin oxide having high conductivity can be obtained at the point where the equal voltage is increased from the inflection point at the beginning regardless of the total flow rate of the introduced gas.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

As described above, according to the present invention,
Instead of investigating changes in the sputtering state by actually analyzing the film quality, the current-voltage characteristics or power-
It is possible to detect the state change and control the quality of the obtained film simply by examining the voltage characteristics.

Further, according to a preferred embodiment of the present invention, the current-voltage characteristic is changed to a desired value by adjusting the mixing ratio of the sputtering gas and the total flow rate of the introduced gas, and the desired value is obtained under the desired condition. It is possible to form a film having the following quality.

Furthermore, according to a preferred embodiment of the present invention,
With the mixed gas ratio to be introduced kept constant, the total flow rate of the introduced gas is changed, the current-voltage characteristics are measured, and both the film formation rate and the film quality can be adjusted to desired values for film formation.

According to another preferred embodiment of the present invention, the film quality is modulated in the depth direction of the film by forming the film while moving the film formation conditions at an appropriate range and speed on the current-voltage characteristics. It is possible to synthesize such novel substances.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a film forming apparatus of the present invention.

FIG. 2 is a diagram showing current-voltage characteristics when a tin target is sputtered with oxygen or a mixed gas of oxygen and argon.

FIG. 3: Tin target with oxygen: argon = 50:
The figure which shows the current-voltage characteristic at the time of sputter | spatterring with the sputtering gas which has a mixing ratio of 50.

[Fig. 4] Oxygen: Argon = 50:
The figure which shows the current-voltage characteristic at the time of sputter | spattering by changing the total flow rate of introduction gas with the sputtering gas which has a mixture ratio of 50.

FIG. 5: Tin target with oxygen: argon = 50:
The figure which shows the film-forming rate per unit current at the time of sputter | spattering by changing the total introduction gas flow rate with the sputter gas which has a mixture ratio of 50.

Figure 6: Tin target, oxygen gas 60c per minute
The figure which shows the power-voltage characteristic at the time of c, sputter | spattering by introducing 30 cc of argon gas per minute.

FIG. 7: The tin target was kept at a mixing ratio of oxygen gas and argon gas of 58:42 and the total introduced gas flow rate was 8 per minute.
The figure which shows the electric power-voltage characteristic at the time of sputtering by setting it as 0 cc.

FIG. 8: The tin target was kept at a mixing ratio of oxygen gas and argon gas of 58:42 and the total introduction gas flow rate was 1 minute / minute.
The figure which shows the electric power-voltage characteristic when it is 10 cc and is sputtered.

FIG. 9: The tin target was kept at a mixing ratio of oxygen gas and argon gas of 58:42, and the total introduction gas flow rate was 1 minute / minute.
The figure which shows the power-voltage characteristic when it is set to 30 cc and is sputtered.

FIG. 10: Tin target, oxygen gas 52.2s
The figure which shows the current-voltage characteristic at the time of sputtering by introducing ccm and 37.8 sccm of argon gas.

FIG. 11 shows the tin target shown in FIG. 10, which is 52.2 sccm in oxygen gas and 37.8 sc in argon gas.
cm was introduced, and the tin oxide film formed at the points indicated by P, Q, and R on the current-voltage characteristics at the time of sputtering was immersed in a 1N sodium hydroxide aqueous solution at 50 ° C., and the tin oxide film was measured. The figure which shows the time change of the ablation amount of.

FIG. 12 is a current-voltage obtained by sputtering a tin target shown by D in FIG. 4 at a mixing ratio of oxygen gas and argon gas of 50:50 and a total introduced gas flow rate of 70 cc / min. The conductivity of the film formed at several points on the characteristics is taken as the vertical axis, and the voltage at the shoulder point of the current-voltage curve, which is the first inflection point when the voltage is increased, and the The figure which showed the difference with voltage as the horizontal axis.

FIG. 13 is a current-voltage obtained by sputtering the tin target shown by E in FIG. 4 while keeping the mixing ratio of oxygen gas and argon gas at 50:50 and the total flow rate of introduced gas at 80 cc / min. The conductivity of the film formed at several points on the characteristics is taken as the vertical axis, and the voltage at the shoulder point of the current-voltage curve, which is the first inflection point when the voltage is increased, and the The figure which showed the difference with voltage as the horizontal axis.

FIG. 14 is a current-voltage obtained by sputtering a tin target shown by F in FIG. 4 at a mixing ratio of oxygen gas and argon gas of 50:50 and a total introduced gas flow rate of 90 cc / min. The conductivity of the film formed at several points on the characteristics is taken as the vertical axis, and the voltage at the shoulder point of the current-voltage curve, which is the first inflection point when the voltage is increased, and the The figure which showed the difference with voltage as the horizontal axis.

[Explanation of symbols]

 1: Sputtering chamber 1a, 1c: Electrode 1b: Target 1d: Substrate 2: Power supply device 3: Gas introduction device 4: Data processing device 5: Vacuum exhaust device

Claims (9)

[Claims] 1. A sputtering gas containing a reactive gas is used,
In the method of forming a film by the DC sputtering method, a data processing device that obtains a functional relationship between at least two of voltage, current and power supplied from a power source to the sputtering device is used, and based on the processing result of this data processing device. A film forming method characterized by controlling sputtering conditions. 2. The film forming method according to claim 1, wherein the sputtering gas is a mixed gas of a reactive gas and a rare gas. 3. The film forming method according to claim 1, wherein in the functional relationship, the film is formed at a voltage near an inflection point of a voltage-current curve that first appears when the voltage is increased. 4. In the functional relation, the film is formed at a voltage between an inflection point of a voltage-current curve that first appears when the voltage increases and a next inflection point. 2. The film forming method as described in 2. 5. A film is formed by keeping the mixing ratio of the reactive gas of the sputtering gas and the rare gas constant.
[4] The film forming method according to any one of [4] to [4]. 6. The film is formed by using as a target a metal that forms a metal oxide exhibiting conductivity in the state of oxygen deficiency or excess metal. Film forming method. 7. The target is Sn, In, Zn, T
i, Th, V, Nb, Ta, Mo, W, Cu, Cr, M
7. The film forming method according to claim 1, wherein at least one selected from the group consisting of n, Fe, Ni, Co, Pr, Bi and Nb is a main component. . 8. A sputtering chamber in which a target and a substrate to be processed are installed, an exhaust device for evacuating the sputtering chamber, a power supply device for applying a voltage to electrodes of the sputtering chamber, and the sputtering device. In a film forming apparatus equipped with a gas introduction device for introducing a mixed gas of a reactive gas and a rare gas into a chamber, a sputtering gas is electrically connected to the power supply and the gas introduction device and receives a data signal from them. A data processing device for determining the mixing ratio, the total flow rate of introduced gas, and the functional relationship between at least two of the voltage, current, and power supplied from the power supply device to the electrode of the sputtering chamber. Characteristic film forming apparatus. 9. The film forming apparatus according to claim 8, further comprising a film thickness measuring device near the substrate in the sputtering chamber.