JP2009120924A - Film forming device and method for forming thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide techniques for accurately measuring a minute deposition amount. <P>SOLUTION: A cooling medium is made to flow in a film thickness sensor 10 to cool a quartz oscillator 32 to the temperature lower than 0°C so as to measure a resonant frequency. As thermal noise is reduced to improve the S/N, a deposition amount of a film forming material with a small vapor emission amount can be accurately measured. For maintenance, a heating medium is made to flow the passage where the cooling medium has flowed so as to heat the film thickness sensor 10, and then air is introduced into a vacuum chamber 11. As no dew condensation occurs on the cooled member, an evacuation time after the maintenance work is finished is shortened, and the formed thin film has high qualities. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field of a film forming apparatus, and more particularly to a technique for forming a thin film while measuring a film thickness.

  When forming a thin film in a vacuum atmosphere, in order to measure the film thickness of the thin film formed on the surface of the film formation target, a film thickness sensor with a quartz resonator is placed in the vacuum atmosphere and placed on the substrate surface. When the film deposition material particles adhere and the thin film grows, the film deposition material particles are also adhered to the crystal unit, and the resonance frequency of the crystal unit that changes according to the amount of deposition is measured to determine the amount of deposition on the substrate surface. In conversion, the film thickness of the thin film formed on the substrate surface is obtained.

  However, when a very small amount of deposition target substance is attached to the substrate, the noise entering the film thickness sensor is larger than the magnitude of the signal obtained by the film thickness sensor, and a very small amount of adhesion is required with high accuracy. There is no problem.

Therefore, in the prior art, the film thickness sensor is cooled to reduce noise.
However, the effect is insufficient. In particular, in the technical field of organic EL elements, the host material and the dopant material such as the coloring material are evaporated together to form the organic coloring layer, so that the host material and the dopant material are contained in the organic coloring layer. A technique for accurately controlling the ratio (dopant ratio) is very important. However, since the evaporation amount of the dopant is very small, a technique for accurately measuring the adhesion amount is required.
Japanese Patent Laid-Open No. 7-34248

  The present invention was created to solve the above-described problems of the prior art, and provides a technique for accurately measuring a minute amount of adhesion.

In order to solve the above-described problems, the present invention has a film forming source disposed in a vacuum chamber, causes film forming material particles released from the film forming source to reach the surface of a film forming object, and forms the film. A film forming apparatus for forming a thin film on a surface of an object, a film thickness sensor disposed at a position where the film forming material particles reach, and the film forming material particles provided in the film thickness sensor attached to the surface A crystal resonator, a measuring device connected to the film thickness sensor and calculating the film thickness of the thin film on the substrate surface from a change in the resonance frequency of the crystal resonator, and the film thickness sensor at a temperature lower than 0 ° C. It is a film forming apparatus having a cooling device for supplying a cooled refrigerant body and a temperature raising device for supplying a heating medium at room temperature or higher to the film thickness sensor.
Moreover, this invention is a film-forming apparatus with which the said cooling device cools the said refrigerant | coolant body to -80 degrees C or less, and supplies it to the said film thickness sensor.
Moreover, this invention is a film-forming apparatus with which the said temperature rising apparatus heats the said heating medium to room temperature higher than room temperature, and supplies it to the said film thickness sensor.
In addition, the present invention releases film forming material particles from a film forming source disposed in a vacuum chamber, attaches the film forming material particles to the surface of the film forming object, and forms a thin film on the surface of the film forming object. A film thickness sensor is disposed at a position where the film forming material particles reach, and a vacuum body is provided in the vacuum chamber to supply a coolant containing liquid nitrogen to the film thickness sensor. The film-forming material particles are discharged while the film-forming material particles are attached to the surface of the crystal unit provided in the film thickness sensor and cooled by the refrigerant body, and the resonance frequency of the crystal unit is changed. It is a thin film formation method which measures and calculates | requires the film thickness of the said thin film of the said film-forming target object surface.
Further, according to the present invention, when air is introduced into the vacuum chamber, a heating medium having a temperature higher than room temperature is supplied to the film thickness sensor before the air is introduced, and the path through which the refrigerant flows Is a method for forming a thin film in which the temperature is raised.

Since the film thickness sensor is cooled to a temperature lower than 0 ° C. to allow the film formation material to reach the substrate surface, the amount of the film formation material adhering to the film thickness sensor can be accurately measured.
Since the air can be introduced into the vacuum chamber after raising the temperature of the low-temperature member to a temperature higher than room temperature, no dew condensation occurs on the film thickness sensor or the piping.

FIG. 1 shows a film forming apparatus 1 of a first example of the present invention.
The film forming apparatus 1 includes a vacuum chamber 11, a film forming source 14 is disposed inside the vacuum chamber 11, and a substrate is disposed at a position facing the film forming source 14 inside the vacuum chamber 11. A holder 19 is arranged.
The substrate 15 is held by the substrate holder 19, and a thin film is formed on the surface of the substrate 15 when fine particles of the film forming material are released from the film forming source 14.

Here, the film-forming source 14 is a sputtering target in which the film-forming material is formed into a plate shape, and the film-forming material particles are released as sputtering particles. As will be described later, the vapor that melts and evaporates the film-forming material. It may be a generation source or another type of film formation source.
The film thickness sensor 10 according to an example of the present invention is disposed at a measurement position in the vacuum chamber 11 where the fine particles emitted from the film forming source 14 arrive.

  FIG. 3 is an internal schematic structural diagram for explaining the film thickness sensor 10. The film thickness sensor 10 includes a housing 31, and a crystal resonator 32 is disposed inside the housing 31. The crystal unit 32 is fixed to the housing 31 by a stopper, and the film thickness detection surface 34 is exposed to the internal space of the vacuum chamber 11 from the window 39 formed in the housing 31.

  The film thickness detection surface 34 is directed to the film formation source 14, and the fine particles emitted from the film formation source 14 adhere to the film thickness detection surface 34 of the crystal resonator 32, and the substrate 15 The same deposition material as the surface adheres. The measurement position at which the film thickness sensor 10 is arranged is provided at a position spaced from the substrate 15 and the film formation source 14 and blocks fine particles of the film formation material flying from the film formation source 14 toward the substrate 15. Therefore, it does not interfere with the film forming operation.

  The film thickness sensor 10 is connected to the measurement device 4, and the measurement device 4 calculates the mass of the film forming material attached to the film thickness detection surface 34 of the crystal resonator 32 from the change in the resonance frequency of the crystal resonator 32. From the correction coefficient stored in the measuring apparatus 4, the amount of adhesion on the surface of the crystal unit 32 is converted into the film thickness on the surface of the substrate 15, and compared with the set film thickness, the film forming operation is continued or ended. It is configured to determine whether or not.

  A heat medium passage 23 through which a liquid or gas flows is formed in the housing 31 of the film thickness sensor 10. The heat medium flow path 23 can be configured by a tube wound around the casing 31 or a through hole formed inside the casing 31.

The cooling device 5 and the temperature raising device 6 are disposed outside the vacuum chamber 11, and one end of the heat medium passage 23 is connected to the cooling device 5 and the temperature raising device 6 via the switching device 8 by the supply pipe 21. It is configured to be connectable to either one of these.
The other end of the heat medium passage 23 is connected to the exhaust gas treatment device 18 by an exhaust pipe 22. FIG. 4 is a schematic diagram for explaining the heat medium flow path 23, the supply pipe 21, and the exhaust pipe 22.

A liquid refrigerant body is arranged inside the cooling device 5.
The refrigerant body is a substance that maintains fluidity even when the temperature is lower than 0 ° C. (for example, a fluorine compound), and preferably a substance that does not lose fluidity even when cooled to a temperature of −80 ° C. or lower (for example, liquid nitrogen). ).
Inside the temperature raising device 6, a gas cylinder and a heating device filled with a heating medium (which may be either gas or liquid, for example, nitrogen gas heated to room temperature or higher) are arranged.

  In the switching device 8, when the cooling device 5 is connected to the film thickness sensor 10 by the supply pipe 21, when the cooling device 5 supplies the cooling medium to the film thickness sensor 10, the cooling medium flows into the heat medium flow path 23, and the film The thickness sensor 10 (in particular, the crystal unit 32) is cooled to the same temperature as the cooling medium.

  On the other hand, when the temperature raising device 6 is connected to the film thickness sensor 10 by the switching device 8, the temperature raising device 6 supplies the film thickness sensor 10 with a heating medium at room temperature or a heating medium heated to a temperature higher than room temperature. To do. In this case, a heating medium heated to room temperature or a temperature higher than room temperature is passed through the heat medium flow path 23, and the passages through which the heating medium flows (supply pipe 21, heat medium flow path 23, exhaust pipe 22) are at room temperature or higher. The temperature is raised to

Since the heating medium flows in the portion where the cooling medium flows inside the vacuum chamber 11, the member cooled by the cooling medium inside the vacuum chamber 11 is heated by the heating medium.
The cooling medium and the heating medium that have flowed inside the film thickness sensor 10 are guided to the exhaust gas treatment device 18 through the discharge pipe, and are safely processed.

A process of forming a thin film on the surface of the substrate 15 by the film forming apparatus 1 will be described.
An evacuation system 17 is connected to the vacuum chamber 11, and the evacuation system 17 is operated to evacuate the vacuum chamber 11.
The film thickness sensor 10 and the cooling device 5 are connected by the switching device 8, and after evacuating until the inside of the vacuum chamber 11 is lowered to a predetermined pressure, the cooling device 5 is cooled to a temperature lower than 0 ° C. while evacuating. A cooling medium is supplied to the film thickness sensor 10, and the crystal unit 32 inside the film thickness sensor 10 is cooled to the same temperature as the cooling medium.

  Next, while maintaining the vacuum atmosphere in the vacuum chamber 11, the substrate 15, which is a film formation target, is carried into the vacuum chamber 11, held by the substrate holder 19, a sputtering gas is introduced from the gas introduction system, and a sputtering power source is used. A voltage is applied to the target provided in the film forming source 14 to sputter the target.

When the sputtering is stabilized, the shutters 24 and 25 are opened, the film forming material particles (sputtering particles in this case) are allowed to reach the surface of the substrate 15, and thin film formation is started.
During sputtering, the sputtered particles reach the film thickness sensor 10 and a thin film is formed on the surface of the crystal unit 32.

  The crystal resonator 32 is set to a temperature lower than 0 ° C., and thermal noise is reduced. Therefore, even when the deposition rate of the film-forming material particles on the surface of the crystal unit 32 is small and the change in the resonance frequency is small, the S / N ratio is improved, so that the amount of deposition can be accurately measured.

FIG. 5 is a graph showing the result obtained by converting the signal of the film thickness sensor output without depositing the film forming material into the film thickness of the substrate surface.
When cooling water (about 20 ° C.) generally used for a film thickness sensor is flowing (0 to 10 minutes in the graph), thermal noise of about 0.06 cm is observed. When the cooling medium was switched at time t and a cooling medium at −80 ° C. was supplied, the thermal noise gradually decreased as the temperature decreased and was no longer observed.

  When the temperature of the crystal unit 32 is different, the probability that the film forming material adheres to the crystal unit 32 changes, or the oscillation frequency of the crystal unit 32 changes. For this reason, it is necessary to change the correction coefficient of the measuring device 4 described later depending on the temperature of the crystal unit 32.

  Further, even if the film forming material is released from the same film forming source 14, the adhesion amount differs depending on the distance from the film forming source 14. Therefore, the resonance frequency of the crystal unit 32 that is arranged at the measurement position and cooled by the cooling medium. From the change, a correction coefficient for obtaining the film thickness of the surface of the substrate 15 is calculated in advance and stored in the measuring device 4.

At the time of film formation, the film thickness of the thin film on the surface of the substrate 15 is accurately obtained from the measured resonance frequency change and correction coefficient.
When the film thickness on the surface of the substrate 15 reaches a preset film thickness value, sputtering is stopped and the substrate 15 is carried out of the vacuum chamber 11.

Next, the non-film-formed substrate 15 is carried into the vacuum chamber 11 and the thin film forming operation is continued according to the above procedure.
As described above, when a thin film is formed on the surfaces of a large number of substrates 15, the target in the film forming source 14 is consumed, and thus it is necessary to replace the target.

  Such maintenance work is performed with the vacuum chamber 11 opened, and the inside of the vacuum chamber 11 is exposed to the atmosphere. When a low-temperature member comes into contact with the atmosphere, condensation occurs on the surface thereof, and the vacuum exhaust time after maintenance is performed. May become longer, or the quality of the thin film after maintenance may deteriorate.

  In the present invention, when maintenance work such as replacement of the film forming source 14 is performed, the supply of the cooling medium is stopped before the film forming work is stopped and before the inside of the vacuum chamber 11 is exposed to the atmosphere. Thus, the connection of the film thickness sensor 10 is switched from the cooling device 5 to the temperature raising device 6, the heating medium is supplied from the temperature raising device 6 to the film thickness sensor 10, and the film thickness sensor 10 or the film thickness sensor 10 is connected. After the members exposed to the vacuum tank 11 such as the supply pipe 21 and the exhaust pipe 22 and heated by the cooling medium are heated to a temperature equal to or higher than room temperature, the inside of the vacuum tank 11 is exposed to the atmosphere.

The humidity in the surrounding atmosphere of the vacuum chamber 11 is controlled so that the dew point is lower than room temperature, and a member whose temperature has been raised to a temperature higher than room temperature does not cause condensation even when exposed to the atmosphere. Moisture does not adhere to the film, and when the thin film forming operation is resumed, the exhaust time until reaching the vacuum atmosphere is short, and a high quality thin film can be obtained.
Although the film forming apparatus 1 of the first example is a sputtering apparatus, the present invention is not limited thereto, and can be used for an inorganic material or an organic material vapor deposition apparatus.

Reference numeral 2 in FIG. 2 is the film forming apparatus 2 of the second example of the present invention, and the same members are denoted by the same reference numerals and description thereof is omitted.
This film forming apparatus 2 is an organic thin film forming apparatus, and a film forming source 12 includes a base material vapor deposition source 13a in which a host material made of an organic compound is arranged and an additive vapor deposition in which a dopant material made of an organic compound is arranged. A source 13b is provided. Heating devices 26a and 26b are connected to the respective vapor deposition sources 13a and 13b. When the host materials and the dopant materials inside the vapor deposition sources 13a and 13b are heated by operating the respective heating devices 26a and 26b, the inside of the vacuum chamber 11 is obtained. The vapor of the host material is released from the base material vapor deposition source 13a, and the vapor of the dopant material is emitted from the additive vapor deposition source 13b.

The vapor of the dopant material is smaller than the vapor of the host material, and when both vapors are released together, an organic thin film in which the dopant material is added to the host material is formed on the substrate surface.
A film thickness sensor 10a for the host material is disposed at a position where the vapor of the host material reaches but does not reach the vapor of the dopant material (position where the vapor of the reaching dopant material is so small that it can be ignored). The film thickness sensor 10b for the dopant material is disposed at a position where the vapor of the host material reaches but does not reach the vapor of the host material (a position where the amount of vapor of the host material that reaches the layer is negligibly small).

Each film thickness sensor 10a, 10b is connected to the cooling device 5 and the temperature raising device 6 via the switching device 8, respectively.
Each film thickness sensor 10a, 10b is configured to be switched together by the switching device 8 to either the cooling device 5 or the temperature raising device 6, and started evacuation inside the vacuum chamber 11. Thereafter, each film thickness sensor 10a, 10b is connected to the cooling device 5, and after the inside of the vacuum chamber 11 is evacuated to a predetermined pressure, a cooling medium is supplied to each film thickness sensor 10a, 10b. The quartz oscillators arranged in the thickness sensors 10a and 10b are each cooled to the temperature of the cooling medium.

When the vapor of the host material and the vapor of the dopant material are released from the film forming source 12 in this state, an organic thin film is formed on the surface of the substrate 15.
At this time, when the crystal resonator 32 in the dopant film thickness sensor 10b is cooled to a temperature lower than 0 ° C., the vapor of the dopant material adheres to the surface of the crystal resonator 32 and changes the resonance frequency. The amount of adhesion on the surface of the substrate 15 can be accurately obtained from the change amount and the correction coefficient.

In the film forming apparatus 2, the host film thickness sensor 10 a also accurately determines the amount of host material adhering to the surface of the substrate 15, and the ratio of the dopant material adhering amount and the host material adhering amount is measured in advance. When it is compared with the content ratio set in the device 4 and does not match, the measuring device 4 supplies the energization amount to the heating device in the steam generation source so that the measured adhesion amount ratio matches the set content ratio. , And the vapor generation amount of the dopant material and the vapor generation amount of the host material can be controlled to approach the set content rate.
Also in the film thickness sensors 10a and 10b of the film forming apparatus 2, the heating medium is supplied by the temperature raising device 6 and the temperature is raised to a temperature equal to or higher than room temperature, and then the vacuum chamber 11 is opened.

First example film forming apparatus of the present invention The film forming apparatus of the second example of the present invention Internal schematic diagram for explaining film thickness sensor Drawing to explain piping of film thickness sensor Graph showing the relationship between the temperature of the cooling medium and the film formation rate on the substrate surface calculated from the change in resonance frequency

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Film-forming apparatus 4 ... Measuring apparatus 5 ... Cooling apparatus 6 ... Temperature rising device 10, 10a, 10b ... Film thickness sensor 12 ... Film-forming source 32 ... Crystal oscillator

Claims (5)

A film forming apparatus having a film forming source disposed in a vacuum chamber, causing film forming material particles released from the film forming source to reach the surface of the film forming object, and forming a thin film on the surface of the film forming object Because
A film thickness sensor disposed at a position where the film-forming material particles reach;
A crystal resonator provided in the film thickness sensor and having the film forming material particles attached to the surface thereof;
A measuring device connected to the film thickness sensor and calculating a film thickness of the thin film on the substrate surface from a change in a resonance frequency of the crystal resonator;
A cooling device for supplying a cooling medium cooled to a temperature lower than 0 ° C. to the film thickness sensor;
A film forming apparatus comprising: a temperature raising device that supplies a heating medium at room temperature or higher to the film thickness sensor.   The film forming apparatus according to claim 1, wherein the cooling device cools the refrigerant body to −80 ° C. or less and supplies the coolant to the film thickness sensor.   The film forming apparatus according to claim 1, wherein the temperature raising device heats the heating medium to a temperature higher than room temperature and supplies the heating medium to the film thickness sensor. In this thin film forming method, film forming material particles are released from a film forming source disposed in a vacuum chamber, the film forming material particles are adhered to the surface of the film forming target, and a thin film is formed on the surface of the film forming target. And
A film thickness sensor is arranged at a position where the film forming material particles reach,
The film forming material particles are released while supplying a refrigerant body containing liquid nitrogen to the film thickness sensor in a vacuum atmosphere in the vacuum chamber,
The film-forming material particles are attached to the surface of the crystal unit that is provided in the film thickness sensor and is cooled by the refrigerant body, and the change in the resonance frequency of the crystal unit is measured. A thin film forming method for obtaining the thickness of a thin film.   When introducing the atmosphere into the vacuum chamber, before introducing the atmosphere, a heating medium having a temperature equal to or higher than room temperature is supplied to the film thickness sensor to raise the temperature of the path through which the refrigerant body flows. 5. The thin film forming method according to 4.

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