JP2726149B2 - Thin film forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus using an organic metal gas, for example, metal atoms and capacitors used for wiring, electrodes, barrier metals, etc. of high-density integrated circuits. The present invention relates to a thin film forming apparatus for forming a high quality thin film by depositing semiconductor atoms such as Si and Ga used for an insulator, etc. on a substrate by a low temperature process with good controllability.

[Conventional technology]

In order to realize a high-density integrated circuit, there is a strong demand for a method for producing a high-quality thin film at a low temperature in order to avoid adverse effects on the device due to heat and impurities mixed in the thin film. A new technology that responds to this problem is chemical vapor deposition (CV) using organometallic gas, which forms a thin film by decomposition deposition at a relatively low temperature.
D) A method has been proposed. This technique has an excellent feature that a gas can be decomposed at a relatively low temperature, so that a high-quality conductor, dielectric and insulator thin film can be produced even at a low temperature. In general, when forming a thin film by CVD, increasing the substrate temperature improves the quality of the formed film,
The adhesion to the substrate also increases. By the way, when a metal thin film having high quality and high adhesive force is produced on a substrate by thermally decomposing an organic metal gas by heating with a heater, the ambient temperature rises following the substrate temperature. As a result, the organometallic gas itself is decomposed in the gas phase, thereby forming impurities of carbides and oxides by the secondary reaction in the gas phase, thereby producing high-quality conductor, dielectric and insulator thin films. However, there has been a problem that constituent atoms necessary for the deposition cannot be supplied and deposited on the substrate without containing impurities.

Fig. 2 shows, for example, Taki et al.'S Present and Future Materials Processing
Materials Processing) (1990) pp. 206-210 is a block diagram showing a conventional thin film forming apparatus that uses a photoexcitation effect by heating with a laser and irradiating a laser. In the figure, reference numeral 1 denotes a film forming gas. Carrier gas, such as helium, 2 is a reaction chamber, 3 is a film forming gas supply tank, 5 is a mass flow controller for controlling the amount of film forming gas supplied, 8 is a film forming gas supply port, 9 Is a substrate on which a film is formed, 10 is a susceptor with a heater as a substrate heating device for heating the substrate 9, 11 is a vacuum pump, 12 is an outlet on the vacuum pump side, 18 is an ultraviolet laser oscillator, 19 is an ultraviolet laser beam, Reference numeral 20 denotes a cylindrical telescope for shaping the ultraviolet laser light 19 from the ultraviolet laser oscillator 18 into an energy density necessary for dissociation of the film forming gas, and 21 shuts off the film forming gas atmosphere and the atmosphere, and Window for introducing light into the reaction chamber 2, 22 is a supply port of the purge gas for suppressing deposition of the decomposition product of the window 21 due to the decomposition of the film forming gas.

 Next, the operation will be described.

Ultraviolet laser light 19 emitted from an ultraviolet laser oscillator 18
Is shaped by a cylindrical telescope 20 to have an energy density equal to or higher than the energy density required for dissociating the film-forming gas, and is introduced into the reaction chamber 2 through the window 21. The ultraviolet laser light 19 is
By changing the direction of the susceptor 10 with a heater,
Irradiated parallel or perpendicular to

When only thermal decomposition by a heater is used, an organic metal gas as a film forming gas is heated and decomposed and deposited on the substrate 9 to form a thin film. In the prior art, in order to produce a high-quality film having a high adhesive force at a high speed, the heater is expected to increase the decomposition rate of the organometallic gas on the surface of the substrate 9 and the migration effect of the deposit. The substrate was heated by the attached susceptor 10. In addition, when utilizing the excited decomposition of an organometallic gas in the gas phase by photoexcitation,
Excited species formed in the gas phase are deposited on the substrate by diffusion to form a thin film. However, even in this case, without heating the substrate 9, a high-quality thin film with strong adhesive force cannot be obtained. Is also used.

By the way, the ambient temperature rises due to the rise in the substrate temperature, and impurities such as carbides are formed in the gas phase,
This impurity may be mixed into the film. That is, when the substrate temperature is increased by heating with a heater or laser irradiation to improve the film quality, the ambient temperature is also increased accordingly, and when the temperature becomes lower than a certain temperature, carbides or oxides of atoms constituting the organic metal gas are formed. Impurities are formed in the gas phase and incorporated into the film. In other words, in the prior art, in order to improve the film quality, the ambient temperature is increased by increasing the heater temperature, and even if impurities such as carbides are generated in the gas phase, the ambient temperature cannot be controlled, or the impurities cannot be controlled. Since the process for controlling the generation was not incorporated into the apparatus, it was not possible to avoid the contamination of the film with impurities.

[Problems to be solved by the invention]

Since the conventional thin film forming apparatus is configured as described above, when the organic metal gas is thermally decomposed on the substrate by heating with a heater, the organic metal gas is thermally decomposed even in the atmosphere, and is adsorbed on the substrate 9 to be thinned. There is a problem that impurities such as carbides generated by a secondary reaction of a precursor that forms sapphire are prevented from being mixed into the film. Further, in order to improve the quality of the film deposited and decomposed by diffusing the organic metal gas onto the substrate, a method of further heating the substrate 9 at a higher temperature was used in combination with the method of heating the substrate 9 at a higher temperature even if the temperature of the thin film was lowered to some extent. The secondary reaction in the inside becomes more active, and impurities such as carbides are generated, which makes it difficult to produce a high-quality thin film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and uses an organometallic gas that can be decomposed at a low temperature to control the atmosphere on a substrate to reduce the environment in the gas phase.
An organic metal gas-based thin film forming device that can obtain the expected film quality by depositing a thin film from an organic metal gas containing no impurities or a decomposition product thereof while maintaining a state in which no impurities are generated by the next reaction The purpose is to obtain.

[Means for solving the problem]

In the thin film forming apparatus according to the first aspect of the present invention, a substrate heating apparatus for heating and decomposing and depositing an organic metal gas on a substrate and an atmosphere immediately above the substrate under a set pressure so that impurities are not generated by dissociated molecules. A gas temperature cooling device for cooling to a temperature, and the substrate heating device or the gas temperature cooling device according to the generation of the impurities formed by the secondary reaction in the gas phase of the atmosphere or the monitoring result of the temperature of the atmosphere. And a reaction control device for controlling at least one of the operations.

The thin film forming apparatus according to the second aspect of the present invention includes a substrate heating apparatus for heating a substrate to decompose and deposit an organic metal gas, and a gas for cooling an atmosphere immediately above the substrate to a temperature at which impurities are not generated by dissociated molecules. A temperature cooling device, and a reaction control device for controlling at least one of the substrate heating device and the gas temperature cooling device so that the substrate ambient temperature is 400 ° C. or less.

[Action]

In order to improve the quality of a thin film forming precursor adsorbed on a substrate, the thin film forming apparatus according to the present invention cools a gas temperature immediately above the substrate by a gas temperature cooling device and causes the precursor adsorbed on the substrate to be directly above the substrate. The reaction controller controls the reaction according to the monitoring results of impurities such as carbides formed as a result of the secondary reaction in the gas phase, and deposits the organic metal gas on the substrate surface by heat, light or Decomposed and deposited with the energy of electrons. At this time, the gas temperature cooling device cools to a temperature at which impurities such as carbides due to dissociated molecules do not occur under the set pressure, and does not include impurities such as carbides generated by the secondary reaction, and forms an organometallic gas. The use of excited species having little or no impurity atoms as precursors for substrate adsorption enables the production of thin films containing no impurities. Also,
Controlling the generation of impurities in the gas phase by steepening the temperature gradient between the gas temperature cooling device and the substrate surface in order to raise the temperature of the substrate to a higher temperature and to form a higher quality and stronger adhesive thin film To make it feasible. In addition, it is possible to improve reduction in step coverage due to generation of impurities as in the related art.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be described using W as an organometallic gas.
The figure will be described for the production of a high-purity W film by CVD using (CO) ₆ [tungsten carbonyl]. In the figure, 1 is a carrier gas such as helium for introducing the organometallic gas as a vapor into the reaction chamber 2, 3 is a supply tank of the organometallic gas, 4 is an automatic opening / closing valve,
Reference numeral 5 denotes a mass flow controller for controlling a supply amount of a film forming gas; 6, a pressure adjusting device controlled by a CVD controller 7 as a reaction control device; 8, a supply port of the film forming gas;
Is a substrate, 10 is a susceptor with a heater as a substrate heating device for thermally decomposing an organic metal gas, 11 is an exhaust port for exhausting by a vacuum pump 12, 13 is a temperature measuring terminal for measuring a substrate temperature and an ambient temperature, 14 Is a power supply device controlled by the CVD control device 7, 15 is a gas temperature cooling device, 16 is a quadrupole gravimetric analyzer for detecting generation of impurities such as carbides, 17
Is an impurity and temperature monitoring device.

 Next, the operation will be described.

Organometallic gas W (CO) supplied into the reaction chamber 2
_As a method of decomposing _{6, there} is a method of thermal decomposition by a heater, excitation decomposition by laser light or electron beam having an appropriate energy density or wavelength for decomposition of an organic metal gas, or a method using both heater heating and excitation decomposition. . Here, an example of a method using only heater heating as an energy source for depositing a thin film on the substrate 9 by decomposing an organic metal gas will be described.

First, the details of the portion of this method in which the organic metal gas is decomposed and deposited by heater heating will be described. The temperature of the substrate 9 on the susceptor 10 with a heater is heated to a temperature at which an organic metal gas can be decomposed and deposited to form a thin film. At this time,
The output signal of the quadrupole gravimeter 16 is detected by the monitor device 17, and based on the detected output, the CVD controller 7 controls the ambient temperature and the substrate temperature to an environment in which impurities such as W carbide are not generated. Further, the pressure adjusting device 6 controls the pressure in the reaction chamber 2, and further controls the gas supply amount into the reaction chamber 2 by the mass flow controller 5. Thereby, formation of impurities such as W carbide and W oxide due to atoms constituting the organometallic gas can be avoided.

Further, for example, under the condition of a pressure of 2 Torr or more, when the ambient temperature immediately above the substrate 9 becomes 400 ° C. or more due to the heating of the heater, impurities such as W carbide and W oxide are generated. It is not possible to supply alone on the surface of the substrate 9. However, in this case, the CVD controller 7 controls the ambient temperature immediately above the substrate 9 to 400 ° C. or less by the gas temperature cooling device 15 based on the detection output of the temperature measuring element 13 to avoid the generation of impurities. And a higher quality thin film can be formed with high adhesion. However, in this case, even if the pressure is reduced to less than 2 Torr, the generation of impurities can be avoided, but the deposition rate is drastically reduced and the productivity is deteriorated. That is, in the conventional thin film forming apparatus, even in a condition where the organic metal gas W (CO) ₆ is decomposed directly above the substrate 9 and impurities are generated, the effect of the gas temperature cooling allows the atmosphere to be cooled. The generation of impurities can be suppressed, and a thin film having high quality and high adhesion can be produced at a high speed. Further, even if the pressure is lower than 2 Torr, if a temperature just above the substrate 9 is set to 400 ° C. or higher to form a high-quality thin film, the generation of impurities in the gas phase increases. The ambient temperature just above 9
It is necessary to control the temperature to 400 ° C. or less. That is, even if the substrate surface temperature is raised beyond the conventional controllable range in which impurities are generated, the secondary reaction of the excited species can be performed by adding control by the gas temperature cooling device 15 in addition to the above-described control of the pressure and the like. The formation of W carbides and W oxides formed as a result of the above can be avoided, and only undecomposed (CO) ₆ or excited species W (CO) × (x = 0 to 5) can be supplied onto the substrate. It has become possible.

In the above embodiment, the organic metal gas is decomposed and the substrate 9 is decomposed.
As a method of depositing a thin film thereon, a method using heater heating has been described. However, as an energy supply source other than heater heating, a laser light source in the absorption wavelength region of the substrate 9 and a lamp light heating device are used alone or in combination with heater heating. Alternatively, a substrate heating source such as an electron beam and an ion beam may be used. In addition, only the surface of the substrate 9 is instantaneously heated selectively by pulse heating using a laser light source that does not absorb the organic metal gas to reduce the amount of heat transferred to the gas phase. By lowering the pressure and suppressing the heat transfer of the gas temperature in the gas phase, it is possible to prevent the excited species supplied into the reaction chamber 2 from further causing a decomposition reaction to generate impurities such as W carbide, A higher quality thin film can be formed.

In the above embodiment, W (CO) ₆ is used as the organic metal gas.
Is shown, Mo (CO) ₆ , Cr (CO) ₆ , V (C
The present invention can be applied to the case where a carbonyl-based organic metal gas such as O) ₆ Ni (CO) ₄ and Fe (CO) ₅ is used, and the same effects as in the above embodiment can be obtained.

Thus, by the CVD control system including the gas temperature cooling device, the pressure adjusting device, the gas flow adjusting device, and the like,
By controlling the atmosphere to an environment that does not generate impurities such as carbides and supplying only the undecomposed organometallic gas or its excited species optimal for high-quality film formation on the substrate 9 and decomposing and depositing the same to produce a thin film. it can. Further, even when higher temperature heating is required for film reforming, the gas supply amount and pressure are controlled by the CVD control device 7 and the ambient temperature immediately above the substrate 9 is controlled by the gas temperature cooling device 15. By suppressing the generation of impurities from the organic metal gas, a thin film having higher quality and higher adhesive force can be formed on the substrate 9.

〔The invention's effect〕

As described above, according to the invention of claim 1, a substrate heating device that heats a substrate and decomposes and deposits an organometallic gas,
A gas temperature cooling device that cools an atmosphere immediately above the substrate to a temperature at which no impurities are generated by dissociated molecules under a set pressure, and generation or generation of the impurities formed by a secondary reaction in a gas phase of the atmosphere. Is configured to provide a reaction control device for controlling at least one of the substrate heating device and the gas temperature cooling device in accordance with the monitoring result of the temperature of the atmosphere, so that the substrate surface temperature is increased to improve the film quality. Even when the thickness exceeds a certain boundary thickness, the ambient temperature does not rise, and only the organometallic gas or its excited species can be decomposed and deposited on the substrate in the gas phase, and the expected high temperature without impurities such as carbides can be obtained. There is an effect that a thin film having high quality, high adhesion and good throwing power can be formed on a substrate.

According to the invention of claim 2, a substrate heating device for heating the substrate to decompose and deposit the organic metal gas, and a gas temperature cooling device for cooling the atmosphere immediately above the substrate to a temperature at which no impurities are generated by dissociated molecules. And the substrate ambient temperature is 40
A reaction control device for controlling the operation of at least one of the substrate heating device and the gas temperature cooling device so as to be 0 ° C. or less is provided.
By controlling as follows, the generation of impurities can be avoided, and there is an effect that a thin film having higher quality, high adhesion and good throwing power can be formed on the substrate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a thin film forming apparatus according to one embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional thin film forming apparatus. 2 is a reaction chamber, 7 is a reaction control device (CVD control device), 9 is a substrate, 10 is a substrate heating device (susceptor with a heater), and 15 is a gas temperature cooling device. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] 1. A thin film forming apparatus for decomposing an organic metal gas in a reaction chamber to deposit and form a thin film on a substrate, comprising: a substrate heating apparatus for heating the substrate to decompose and deposit the organic metal gas; A gas temperature cooling device that cools an atmosphere immediately above a substrate to a temperature at which impurities are not generated by dissociated molecules under a set pressure, and generation or generation of the impurities formed by a secondary reaction in a gas phase of the atmosphere. A thin film forming apparatus comprising: a reaction control device that controls at least one of the substrate heating device and the gas temperature cooling device in accordance with a result of monitoring the temperature of the atmosphere. 2. A thin film forming apparatus for decomposing an organic metal gas in a reaction chamber to deposit and form a thin film on a substrate, comprising: a substrate heating device for heating the substrate to decompose and deposit the organic metal gas; Operation of at least one of a gas temperature cooling device that cools an atmosphere immediately above a substrate to a temperature at which impurities are not generated by dissociation molecules, and at least one of the substrate heating device and the gas temperature cooling device so that the substrate atmosphere temperature is 400 ° C. or less. And a reaction control device for controlling the pressure.