JPS6312938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film manufacturing apparatus for forming a film on a substrate, and more specifically, to an improvement of a reactive sputtering apparatus.

Conventionally, a sputtering apparatus is well known as an apparatus for forming a metal thin film on a substrate. especially,
Reactive method is a method of sputtering metal in an active gas atmosphere and producing a thin film of reaction products (hydrogen compounds, oxides, nitrides, etc.) with the gas.
This is called sputtering, and an example of the device is shown in FIG. This device generally consists of a vacuum vessel 1
A target 7 made of a material to be sputtered and a substrate 101 to be deposited are placed in the container as shown in the figure, and the container 1 is evacuated by a predetermined vacuum evacuation device (not shown). . When a predetermined degree of vacuum is obtained, the reaction gas (N ₂ ) passing through the flow meter 19 and the inert gas (Ar) passing through the flow meter 20
are mixed at a predetermined ratio, and the total flow rate is adjusted by a flow meter 17 before flowing into the container 1. Note that the exhaust pipe 21 is for exhausting excess gas in that case. Next, the power supply 8 is activated to start sputtering, and a desired reaction product film is formed on the substrate 101 in this reaction gas atmosphere. In addition, in the case of a continuous sputtering apparatus for mass production, a specific rail 2 and a driving device (not shown) for the same are added in order to move the substrate. In the figure, 2 is a substrate cassette rail, 3 is a heating chamber, 4 is a cooling chamber, 5 is a main valve, 6 is a bypass, 7 is a target, and 10, 11 and 18 are flow rate control valves.

In film formation using this conventional apparatus, the thickness of the deposited film and the like are controlled by adjusting the target voltage. This may also be possible if the deposit is formed using a laboratory device such as a bell jar. However, when sputtering is carried out continuously on an industrial basis, such as in a dry process, there are the following drawbacks. To keep the discharge voltage constant,
Measures were taken such as visually observing the discharge voltage value and changing it manually, or changing the conductance between the sputtering chamber and the diffusion pump in the exhaust system to change the degree of vacuum in the sputtering chamber. Further, regarding the control of the discharge gas, it is necessary to use a mixed gas of an inert gas and a reactive gas at a predetermined ratio in advance, or to control the inert gas and the reactive gas independently. However, with such a method, it is difficult to deposit a film with strict specification values for film properties. Particularly when attempting to deposit films with various reactivities in one apparatus, the previous conditions significantly influence the properties of the subsequent films, making it impossible to produce films with uniform properties.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a thin film manufacturing apparatus with good film properties that is suitable for mass production systems.

To achieve the above object, the thin film manufacturing apparatus of the present invention, such as a reactive sputtering apparatus, includes a device that analyzes gas during reaction, and adjusts the ratio of gas components flowing into the reaction vessel based on the analysis results. a first gas flow rate control device; a sputter power supply fluctuation detection device for detecting the target voltage of the reaction vessel; and a second gas flow rate control device for adjusting the flow rate of gas flowing into the reaction vessel based on this detection signal. It is characterized by consisting of.

Since the present invention has the above-mentioned configuration, the reaction gas component ratio can always be stably obtained at a predetermined value, and the total amount of reaction gas can be stably obtained at a predetermined value, so that both the film quality and the state of the film are stable. A high quality thin film can be obtained. The details will be explained below using the drawings.

FIG. 2 is a schematic block diagram showing a specific example of the present invention.

A gas flow path 1 is provided in the reactive reaction vessel 101.
Reaction gas is introduced through 12. During the reaction, a part of the reaction gas is extracted and the gas composition is analyzed and detected by the gas mass spectrometer 102. This detected output signal is compared with a preset gas component ratio value, and a command signal for adjusting the flow rate ratio is sent to the first flow rate control device 105. This comparator 12
0 was configured as follows. Of course, other configurations are also possible. The output signal of the mass spectrometer 102 is encoded by a code converter 103 for easy computer processing. This coded signal is compared with a preset gas component ratio value in the computer, and a command signal to adjust the flow rate ratio is sent to the first flow rate control device 105. In the above-mentioned flow rate control device, the flow rate of each of the reaction gases, which are a mixture of multiple gases such as a reaction gas that directly contributes to the reaction and an inert gas for diluting the reaction gas, is adjusted so that the flow rate ratio is a predetermined value. . Since it is a flow rate ratio, it is usually adjusted by the flow rate of one reactive gas. This adjustment of the gas flow rate may be an analog type in which the gas flow rate is adjusted sequentially, or a digital type in which shutoff and conduction are sequentially performed at predetermined time intervals.

On the other hand, even if a desired ratio of reaction gas is obtained, if the overall gas flow rate flowing into the reaction vessel 101 fluctuates sequentially, the quality of the formed film will again be affected.
Therefore, during reactive reaction, target 111
The sputter power supply fluctuation detector 106 detects the variation in the target voltage at . This detected output signal is compared with a preset voltage, and a command signal is sent to the second flow rate control device 109 to adjust the total flow rate. This comparator 130 had the following configuration. Of course, other configurations are also possible. The detected output signal is encoded in a second code converter 107 for easy computer processing. This coded signal is sent to the second computer 10
8, the voltage is compared with a preset set voltage, and a command signal is sent to the second flow rate control device 109 to adjust the total flow rate. In general, the state of the film quality is also affected by the total amount of reactant gas, and the total amount of reactant gas and the target voltage are interrelated.
The flow rate control device makes adjustments so that an appropriate gas flow rate is supplied.

In the above, it has been described as if two completely different code converters and computers were required, but this was done to make the explanation easier to understand, and it would normally be better to effectively perform the functions of two computers. This does not necessarily mean that two devices are required, since programs and other information are built into the device. Furthermore, although the order of gas control is first the gas component ratio and then the total gas flow rate, it goes without saying that this order may be reversed. Furthermore, although the gas flow rate control device is described as requiring the gas flow rate ratio and the total gas flow rate separately, it is possible that only one flow rate control device is required in the case of a flow rate control device that has two functions on the effective stand. Needless to say.

The present invention will be explained in detail below using specific examples.

Example 1 Figure 3 shows this reactive sputtering device
This is an example applied to -N film creation. In the figure, 1' is a sputtering chamber, and 2' is a substrate hole guide rail. The substrates are fed in at regular intervals from the heating and bombardment chamber 3' and exit to the cooling chamber 4'.
When the air is exhausted from the main valve 5' and sputters,
Exhaust through bypass valve 6'. 7 is the target of the Ta metal plate, and 8 is the discharge power source. 9
is a DC voltmeter, which measures the potential in the spatter of the target 7. Inert gas Ar and reactive gas N ₂ for discharge are introduced from 10 and 11. The state of the gas in the sputtering chamber is measured through conductance 12 with 13 quadrupole mass spectrometer tubes. 1
Measurements were made at 13, which is 4 and is used to adjust the exhaust system of the mass spectrometer so that a predetermined amount of the gas to be analyzed is extracted. The amount of spatter gas is mainly A/
D. The signal is input as a signal to the computer 16 through the converter (interface) 15. 16, the time average of these input signals is determined. Next, 16 is stored first. The ratio of Ar and N ₂ is compared with the time average value of the signal described above, and the difference is returned to the gas flow rate control device 19 through 15 again. When N ₂ /Ar is larger than the set value, the flow rate controller 19 is operated to close the N ₂ valve 11 so that the inflow of N ₂ decreases. On the other hand, the spatter voltage measured by the DC voltmeter 9 is encoded by the above-mentioned AD converter 15, and then input to the computer 16 as a signal. 16, the time average of these input signals is determined. Next, the sputter voltage previously stored in 16 is compared with the time average value of the signal described above, and the difference is returned to gas flow rate converter 17 through 15 again. Incidentally, the relationship between the sputtering voltage and the Ar gas used for this control is shown in FIG. Solid lines 61, 62, and 63 indicate the gas flow rate, respectively.
150, 100, 50c.c./min. That is, the voltage fluctuation is inputted to the gas (Ar+N ₂ ) inflow valve 18 through the flow rate controller 17, and when the difference is positive, the inflow amount is increased. This method improves the characteristics of the Ta ₂ N film with excellent reproducibility and uniformity by keeping the discharge voltage and N ₂ /Ar ratio constant.

FIG. 4 is an explanatory diagram showing the effect of the discharge voltage according to the present invention, and shows the temporal fluctuation of the discharge voltage before and after using this system. Before using this system, as shown by the solid line 1, there was a period of several hours and a fluctuation of about ±200V even in short periods with respect to the setting of 5.0KV. As shown by solid line 2, the fluctuation is less than ±30V, and it is now possible to reproduce the difference in set value of ±50V. Furthermore, when we measured the sheath resistance of the films deposited before and after introducing this system, we found that before the introduction of the present invention, there was a wide range of variation in sheet resistance and only ~40% of the sheets fell within the target value. Therefore, when using the system of the present invention, more than 95% of the products were able to be produced within the target specifications.

Example 2 Although the method described in Example 1 uses a continuous deposition apparatus as a sputtering apparatus, the present invention can be similarly applied to a batch-type deposition method. A schematic configuration diagram of this embodiment is shown in FIG.
The reaction vessel 201 is a bell jar commonly used in laboratories, etc., and the sample 203 placed on the sample holder 202 is replaced every time a predetermined sputter deposition is completed. It will be done. In addition, in the control system, the first code conversion device 151, the first computer 161,
and a first source code conversion device 152 that converts the converted first code into the original code. Further, the second code conversion device 153 transmits and controls the signal using the sputter voltage.
It consists of a second computer 162, and a second source code conversion device 154 that returns the converted second code to the original code. Since the operation and the like are the same as in the case of FIG. 3, the explanation will be omitted.

In this example, unlike the continuous sputtering described above, the sample to be deposited does not move during the sputtering process, so a more stable reaction gas atmosphere is obtained and a homogeneous sputtered coating layer is formed. It was done. Furthermore, since the gas composition was controlled by a two-step control method of gas analysis and target voltage, a film with a more stable composition was obtained. Furthermore, with this two-step control method, when sputtering was conventionally performed in a single bell gear, the concentration of the reaction gas or the gas component ratio fluctuated as the film was formed, but this can no longer be observed, resulting in a good film. Now I can get it.

Example 3 Examples 1 and 2 describe the difference between the sputtering methods, and the targets are
In this case, a Ta metal plate was used to obtain a Ta-N film using Ar+N ₂ gas, but the present invention is not limited to a Ta-N film.
Ta−Al−Si, Ta−Si, Ta−Al−TiTi, Si,
All single-element metals, mixed multi-element metals, or alloys such as Cu, Zr, Zn, Al, etc., with a target resistance of at least 10 kΩ or less, are formed using the equipment used in Examples 1 and 2 above. It was done. Further, as the reaction gas, gases such as N ₂ , O ₂ , H ₂ and the like, which are gases at room temperature, were similarly realized, and a good film was formed. Since the functions, effects, etc. are exactly the same, detailed explanation will be omitted. This will be easily understood by those in the same industry.

Next, another embodiment of the present invention will be described. Figure 7 shows chemical vapor coating equipment (hereinafter abbreviated as CVD equipment)
The present invention is applied to. A part of the CVD reaction container 301 is opened so that a sample 303 can be continuously transferred for mass production. this
In CVD, silane (SiH ₄ ) and oxygen (O ₂ ) gas or a predetermined oxygen-containing gas is used as the reaction gas because it is generally used as a passivation film and an oxide film is formed. Needless to say, if a nitride film is required as passivation, nitrogen gas may be used instead of oxygen. Further, in order to improve the passivation effect, a gas to add impurities such as phosphorus (P) may often be mixed.

Now, in this CVD apparatus, it is only necessary that the above-mentioned reaction gases are sufficiently mixed to form a film on the substrate 303, and there is no need to maintain the inside of the apparatus at a high degree of vacuum as in the case of a sputtering apparatus. However, in order to form a uniform film quality, temperature control is required to maintain the hotpot 302 that heats the substrate 303 at a predetermined temperature. In the sputtering device, the voltage of the target is controlled, but this CVD device is characterized in that the voltage of the hot plate is controlled. In this way, in the present invention, things that require control under stricter conditions are the objects to be controlled.

That is, gas analysis of the reaction gas 304 is performed by the mass spectrometer 313, and a predetermined control signal is transmitted to the first flow rate control device 319 to adjust the flow rate of the silane gas. On the other hand, the hot plate 30
The second voltage fluctuation is detected by the electric signal detector 308, and after a predetermined operation is performed by the computer 362, a control signal is transmitted to the second flow rate control device 317 to adjust the flow rate of the entire reaction gas. .

In the past, the hot plate temperature control system was completely independent of the reaction gas, but with this device, it is now possible to control the mutual relationship between the reaction gas and the hot plate, resulting in a more homogeneous passivation film than before. It has the advantage of being able to be formed and mass-produced.

FIG. 8 is a schematic diagram of an epitaxial manufacturing apparatus as still another embodiment of the present invention. This epitaxial reaction vessel 601 is also partially opened to allow mass production. This epitaxial device uses silicon tetrachloride (SiCl ₄ ) gas and hydrogen gas (H ₂ ) as reaction gases to form a Si single crystal film. Needless to say, other gases for adding conductivity type impurities may be used as necessary.

In the case of this epitaxial device as well, the composition of the reaction gas is separated by the mass spectrometer 613 and a predetermined control signal is transmitted to the first gas flow rate control device 619 to adjust the reaction gas component ratio. Next, the electrical signal detector 608 detects voltage fluctuations in the heater 602 of the epitaxial container 601, and transmits a predetermined control signal to the second gas flow rate control device 617 to adjust the flow rate of the entire reaction gas.

In this system, the temperature control system of the furnace heater for epitaxial equipment was performed completely independently of the reaction gas, but with this system, the temperature control system is controlled after adjusting the mutual relationship between the reaction gas and the furnace heater. This has the advantage that it is now possible to produce epitaxial films that are more homogeneous than before, and mass production is now easier.

As explained above, according to the present invention, by always keeping the partial pressure of the reactive gas in the discharge uniform at the same time as the discharge voltage, even in areas that are extremely sensitive to the partial pressure of the reactive gas, which was originally impossible, It is possible to produce membranes with good reproducibility within and between lots.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional reactive sputtering device. FIG. 2 is a block diagram showing the concept of the present invention. FIG. 3 and FIG. 6 are a schematic configuration diagram and a characteristic diagram of an example of a reactivis sputtering device as an embodiment of the present invention. FIG. 4 shows the relationship between deposition time and sputtering voltage, which is an explanatory diagram for showing the effectiveness of the present invention. 5, 7, and 8 are schematic configuration diagrams showing other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Sputtering chamber, 2... Substrate cassette rail, 3... Heating chamber, 4... Cooling chamber, 5... Main valve, 6... Bypass, 7... Target, 8
... Sputter power supply, 9 ... Sputter power supply fluctuation detection, 10 ... Ar gas inlet, 11 ... Reaction gas inlet, 12 ... Conductance, 13 ... Quadrupolar mass, 14 ... Differential exhaust, 15 ... ...Interface, 16...Computer, 17...Flow rate controller, 18...Flow rate control valve, 19, 20...Flow rate controller.

Claims (1)

[Scope of Claims] 1. A thin film forming container having at least a gas inflow means and an electrical input means used for forming a thin film;
a gas analysis means for analyzing the reaction gas in the container;
means for comparing the output signal of the analysis means with a predetermined reference value; first flow rate control means for adjusting the gas flow rate ratio based on the difference between the output signal of the analysis means and the predetermined reference value; electrical signal detection means for detecting a predetermined voltage of the thin film forming container; means for comparing the output signal of the detection means with a predetermined reference value; A thin film manufacturing apparatus comprising a second flow rate control means for adjusting the total amount, characterized in that the first flow rate control means and the second flow rate control means are connected to the gas inflow means. Thin film manufacturing equipment. 2. The thin film manufacturing apparatus according to claim 1, wherein a reactive reaction vessel is used as the thin film forming vessel. 3. The thin film manufacturing apparatus according to claim 1, wherein a CVD thin film forming container is used as the thin film forming container. 4. The thin film manufacturing apparatus according to claim 1, wherein an epitaxial thin film forming container is used as the thin film forming container. 5. The thin film manufacturing apparatus according to claim 1, wherein the comparison means comprises a code conversion device and a computer.