JP2005064264A - Thin film formation method, and particle number evaluating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film formation method capable of decreasing the number of particles on a substrate, and a particle number evaluating method. <P>SOLUTION: In a process of introducing film formation gas and forming a film by CVD, a temperature in a route to the inside of a shower head at the upper place of a reaction chamber from the system including a vaporization system is set at a temperature which is not lower than a vaporization temperature but not higher than a decomposition temperature of at least one of materials and where the number of particles generated during the film formation process reaches the minimum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film manufacturing method and a particle number evaluation method, and more particularly to a thin film manufacturing method and a particle number evaluation method capable of reducing the number of particles when a thin film is manufactured by a CVD method such as MOCVD.

  Conventionally, in a film formation method by a CVD method, particularly a MOCVD (metal organic chemical vapor deposition) film formation method in which a liquid or solid raw material composed of an organometallic compound is vaporized and reacted on a substrate to form a film, In order to satisfy the demand for high integration of semiconductor elements, how to reduce particles (dust) generated by deposition and decomposition of raw materials has been a serious problem. For this reason, attempts have been made to reduce the number of particles from various angles such as the structure of the CVD apparatus, the raw material species, and the vaporization method, but the problem has not yet been solved.

  Regarding the measurement of the number of particles, in the thermal CVD method, since it is difficult to discriminate between morphology roughness and particles due to high-temperature film formation and the effect thereof, a firm measurement method has not been established.

  The object of the present invention is to reduce the number of particles on the substrate by optimizing the combination of raw materials, solvents, etc. and the device temperature control by establishing a particle evaluation method when producing a thin film by the CVD method. An object of the present invention is to provide a method for producing a thin film and a method for evaluating the number of particles.

  According to the first aspect of the present invention, the thin film manufacturing method of the present invention provides a film forming gas composed of a raw material gas obtained by vaporizing a liquid obtained by dissolving a solid raw material or a liquid raw material in a solvent using a vaporization system and a reactive gas through a shower head. In the thin film manufacturing method by the CVD method, which is introduced into the reaction chamber and deposited on the substrate heated above the decomposition temperature of the raw material gas, the route from this system to the inside of the shower head above the reaction chamber, including the vaporization system The film is formed by setting the temperature at a temperature higher than the vaporization temperature of at least one of the raw materials and lower than the decomposition temperature. By setting the temperature of the deposition gas transport path within a specific range, the number of particles on the substrate can be reduced.

According to the second aspect of the present invention, the film is formed by setting the temperature of the path to a temperature at which the number of particles generated during the film forming process is minimized.
According to claim 3, while changing the substrate temperature stepwise within the temperature range from near the vaporization temperature to the decomposition temperature of a single raw material, a film forming gas containing this raw material is flowed over the substrate at each temperature, The film is formed by setting the temperature of the path at or near the temperature at which the number of particles generated on the substrate is minimized.

  According to the fourth aspect of the present invention, the film forming gas containing each raw material at each temperature is placed on the substrate while gradually changing the substrate temperature within the temperature range from the vicinity of the vaporization temperature of each raw material to the decomposition temperature. The film is formed by setting the temperature of the path at or near the temperature at which the total number of particles of each raw material generated on the substrate is minimized.

  According to claim 5, while changing the substrate temperature stepwise in the temperature range from near the vaporization temperature to the decomposition temperature of a plurality of raw materials, a film forming gas containing the plurality of raw materials is flowed on the substrate at each temperature, The film is formed by setting the temperature of the path at or near the temperature at which the number of particles generated on the substrate is minimized.

  According to the sixth aspect of the present invention, the film is formed while maintaining the temperature of at least a part of the path within a range of ± 30 ° C. of the substrate temperature at which the number of particles is minimized. Out of this temperature range, the number of particles increases.

According to claim 7, the raw material is an element selected from Pb, Zr, Ti, Ba, Sr, Ta, Bi, La, Ru, Ir, Ni, Mn, Pr, Si, Al, Hf, Mg, and Ca. It contains at least one of the above.
According to claim 8, the raw material is an organometallic compound.

According to claim 9, the organometallic compound is Pb (thd) ₂ ((bis (2,2,6,6) tetramethyl (3,5) heptanedionate) lead), Zr (thd) ₄ (( Tetrakis (2,2,6,6) tetramethyl (3,5) heptanedionate) zirconium), Zr (dmhd) ₄ ((tetrakis (2,6) dimethyl (3,5) heptanedionate) zirconium), Ti (i-PrO) ₂ (thd) ₂ ((bisisopropoxide) (bis (2,2,6,6) tetramethyl (3,5) heptanedionate) titanium), Zr (MMP) ₄ (( At least one organometallic compound selected from tetrakis (1) methoxy (2) methyl (2) propoxy) zirconium) and Ti (MMP) ₄ ((tetrakis (1) methoxy (2) methyl (2) propoxy) titanium) It is characterized by being.

According to the tenth aspect, when the raw material is Pb (thd) ₂ or Zr (dmhd) ₄ , the film is formed by setting the temperature of the path to 210 to 270 ° C. Out of this temperature range, the number of particles increases.
According to the eleventh aspect, when the raw material is Ti (i-PrO) ₂ (thd) ₂ , the film is formed by setting the temperature of the path to 180 to 240 ° C. Out of this temperature range, the number of particles increases.

According to the twelfth aspect, when the raw material is Zr (MMP) ₄ , the film is formed by setting the temperature of the path to 170 to 250 ° C. Out of this temperature range, the number of particles increases.
According to the thirteenth aspect, when the raw material is Ti (MMP) ₄ , the film is formed by setting the temperature of the path to 160 to 240 ° C. Out of this temperature range, the number of particles increases.

According to the fourteenth aspect, a plurality of raw materials whose raw materials are Pb (thd) ₂ , Zr (dmhd) ₄ , and Ti (i-PrO) ₂ (thd) ₂ , or Pb (thd) ₂ , Zr (MMP) ₄ , And Ti (MMP) ₄ , and when the plurality of raw materials are vaporized simultaneously, the film is formed by setting the temperature of the path to 190 to 250 ° C. Out of this temperature range, the number of particles increases.
According to claim 15, at least one solvent selected from hexane, cyclohexane, ethylcyclohexane and methylcyclohexane is used as the solvent.

According to claim 16, in order to reduce the number of particles, a film forming gas is introduced into the reaction chamber through a shower head having a structure in which a large-diameter disk type filter of 200 mmφ or more is attached to the primary side of the shower head. It is characterized by forming a film. By attaching a large diameter filter, a reduction in the number of particles can be achieved.
According to the seventeenth aspect of the present invention, an inert gas flow is performed in the exhaust direction along the side wall of the reaction chamber from above the reaction chamber to form a film so as to maintain a low particle number state.

According to the eighteenth aspect of the present invention, there is provided a method for evaluating the number of particles, in which a film forming gas composed of a raw material gas obtained by vaporizing a solid raw material or a liquid obtained by dissolving a liquid raw material in a solvent using a vaporization system and a reaction gas In the method for evaluating the number of particles generated during transportation from the vaporization system to the reaction chamber when a film is formed by CVD on a substrate heated to a temperature higher than the decomposition temperature of the source gas through the reaction chamber ,
(1) While gradually changing the substrate temperature from near the vaporization temperature of a single raw material to near the decomposition temperature, a deposition gas is flowed over the wafer at each temperature, and the number of particles on the wafer at that time is measured.
(2) A substrate temperature at which a minimum number of particles can be obtained from the measured number of particles is selected, and the number of particles at that temperature is being transported from this system into the reaction chamber, including the vaporization system for the film forming gas. It is characterized in that the number of particles generated in the film is set, and the film is formed by setting the transport route to this temperature.

  According to the nineteenth aspect, a film forming gas composed of a plurality of source gases and a reaction gas obtained by evaporating a liquid obtained by dissolving a solid source or a liquid source in a solvent using a vaporization system is introduced into the reaction chamber via the shower head. In the method for evaluating the number of particles generated during transport from the vaporization system to the reaction chamber when forming a film by CVD on a substrate heated above the decomposition temperature of the source gas, (1) For each source, While gradually changing the substrate temperature from near the vaporization temperature of each raw material to near the decomposition temperature, each film-forming gas containing each raw material gas is flowed over the wafer at each temperature, and the number of particles on the wafer at that time is measured. (2) The temperature at which the minimum number of particles is obtained is selected from the total number of particles measured for each raw material, and the number of particles at that temperature is determined as the vaporization cis of the film forming gas. Including arm and the number of particles that occurs during transport to the reaction chamber from the system, and carrying out film formation by setting the path of the transport at this temperature.

  According to the twentieth aspect, a film forming gas composed of a plurality of source gases obtained by vaporizing a liquid obtained by dissolving a solid source or a liquid source in a solvent using a vaporization system and a reaction gas is introduced into the reaction chamber via the shower head. In the method for evaluating the number of particles generated during transport from the vaporization system to the reaction chamber when a film is formed by CVD on a substrate heated above the decomposition temperature of the source gas, (1) At the same time, while vaporizing and gradually changing the substrate temperature from near the vaporization temperature of the raw material to near the decomposition temperature, a film-forming gas containing a plurality of raw material gases is flowed over the wafer at each temperature, and the number of particles on the wafer at that time is determined. (2) Select a temperature at which the measured number of particles is minimized, and determine the number of particles at that temperature from this system to the reaction chamber, including the vaporization system for the film forming gas. And number of particles generated in transmission, and performing film deposition by setting the path of the transport at this temperature.

According to claim 21, the raw material is an element selected from Pb, Zr, Ti, Ba, Sr, Ta, Bi, La, Ru, Ir, Ni, Mn, Pr, Si, Al, Hf, Mg, Ca It contains at least one of the above.
According to Claim 22, the raw material is an organometallic compound.
According to claim 23, the organometallic compound comprises Pb (thd) ₂ , Zr (thd) ₄ , Zr (dmhd) ₄ , Ti (i-PrO) ₂ (thd) ₂ , Zr (MMP) ₄ , Ti ( MMP) is at least one organometallic compound selected from ₄ .

  According to the present invention, by defining the temperature of the path from this system to the reaction chamber including the vaporization system, a thin film manufacturing method and a particle number evaluation method in which particle generation is reduced in the CVD film forming process are achieved. Can do.

  Hereinafter, an apparatus for carrying out the thin film manufacturing method according to the present invention will be described with reference to a schematic arrangement / configuration diagram of the thin film manufacturing apparatus shown in FIG.

  This thin film manufacturing apparatus is connected to a reaction chamber 2 connected to the vacuum exhaust system 1 via a pressure regulating valve 1a and a gas head 3 provided on the upper portion of the reaction chamber, separated by a film forming gas pipe 4. It has a mixer 5 and a vaporization system 7 connected to the mixer 5 by a raw material gas pipe 6. In order to keep the vaporized source gas at a temperature at which the vaporized source gas is not liquefied / deposited / deposited on the apparatus components including the gas pipe, various valves, mixer, and gas head from the vaporization system 7 to the reaction chamber 2, heating means such as a heater And a heat exchanger. The pipe 6 between the vaporization system 7 and the mixer 5 is provided with a valve V1, and the pipe 8 between the vaporization system 7 and the exhaust system 1 is provided with a valve V2, whereby the vaporization system 7 and the mixer 5. The exhaust system 1 can be shut off. This is because the maintenance cycles of the components of the vaporization system 7, the mixer 5 and the exhaust system 1 are different, so that substances such as moisture that adversely affect film formation due to release to the atmosphere are avoided from adhering to these components. Is the purpose. When maintenance is performed with one component open to the atmosphere, the vacuum can be maintained without releasing the other two components to the atmosphere.

Hereafter, each said component is demonstrated in detail.
In the reaction chamber 2, a substrate stage 2-1 having a substrate heating unit for placing a substrate as a film formation target is disposed, and a film is formed on the heated substrate from the gas head 3. Gas is introduced. Excess film forming gas that has not been used for the reaction with the substrate, by-product gas with the film forming gas generated by the reaction with the substrate, and the reactant gas are exhausted by the exhaust system 1. The gas head 3 is appropriately heated and maintained at a temperature at which the introduced gas is not liquefied / deposited / formed.

The gas head 3 provided in the upper part of the reaction chamber 2 has a particle trap as a filter for capturing particles present in the film forming gas, as will be described below for another thin film manufacturing apparatus shown in FIG. A vessel may be provided. The particle trap is preferably provided immediately before the shower hole of the gas head, and is appropriately adjusted to a temperature at which a specific vaporized source element necessary for the reaction is not attached or trapped.
Various film forming pressure conditions can be easily accommodated by the pressure regulating valve 1a provided between the exhaust system 1 and the reaction chamber 2.

The mixer 5 is connected to the vaporization system 7 by a pipe 6 provided with a valve V1, and two gas sources (for example, via a valve V3 and a heat exchanger 9, and then a mass flow controller (not shown)) (for example, , Reactive gas source: inert gas source). The film forming gas uniformly mixed in the mixer 5 is introduced into the gas head 3 through a pipe 4 provided with a valve, and is placed on the substrate stage 2-1 without becoming a laminar flow in the reaction chamber 2. It is supplied to the surface of the deposited film formation object. In addition to the reaction gas source, an inert gas (for example, N ₂ ) supply system is connected to the reaction gas source, and each supply system is controlled by adjusting a valve element. The gas is transported from the gas source to the mixer 5 via a flow rate controller and a heat exchanger. Examples of the reaction gas include a gas suitable for the source gas, for example, H _{2 in} the reduction reaction, NH _{3 in the} nitridation reaction, O _{2 in the} oxidation reaction, and the like. The source gas is a gas obtained by vaporizing a source solution obtained by dissolving an organometallic compound or the like in an organic solvent.

  In the mixer 5, the appropriately heated reaction gas supplied from the reaction gas source and the raw material gas generated by the vaporization system 7 and sent through the pipe 6 maintained at a temperature at which liquefaction / deposition / film formation is not introduced are introduced. -A film forming gas (reaction gas + source gas) is obtained by mixing. This source gas is a gas in which one kind or a plurality of kinds of gases are mixed. The film forming gas thus obtained is introduced into the reaction chamber 2 through the pipe 4.

  The pipes 4 and 6 are connected by a VCR joint, and the VCR gasket of each joint of some pipes is preferably a VCR type particle trap in which a hole is not a ring but a particle trap. . The joint with this VCR type particle trap is set and maintained at a temperature higher than the temperature at which the source gas is not liquefied / deposited, and does not attach or trap the specific vaporized source elements necessary for the reaction. desirable.

  In the film forming gas line between the mixer 5 and the reaction chamber 2, a valve for switching the film forming gas may be provided on the secondary side of the mixer 5. The downstream side of this valve is connected to the reaction chamber 2. During film formation, this valve is opened, and this valve is closed after film formation is completed.

  A raw material supply unit 7 a and a vaporization unit (not shown) are connected to the vaporization system 7. This vaporization system pressurizes and conveys raw material liquids A, B, and C obtained by dissolving a liquid / solid raw material in an organic solvent with a pressurized gas (for example, an inert gas such as He gas), Each flow rate is controlled by each liquid flow rate controller so as to be conveyed to the vaporization section. The vaporizing section is configured to efficiently vaporize the raw material liquid whose flow rate is controlled and supply the raw material gas obtained by the vaporization to the mixer 5. In this vaporization section, when there is only one liquid raw material, a single liquid can be mixed, and when there are a plurality of liquid raw materials, a plurality of raw material liquids can be mixed and vaporized. When vaporizing the raw material liquid, not only vaporize the liquid droplets of the raw material liquid, but also apply gas to the liquid droplets, apply physical vibrations, or apply ultrasonic waves to the vaporization part wall surface. It is preferable to introduce vaporization into the vaporization part as finer liquid particles through the nozzle and vaporize it to increase the vaporization efficiency. Inside the vaporization unit, Al or the like is used so that the droplets or liquid particles can be vaporized as much as possible at the locations where vaporization should be efficiently performed, and to reduce the liquid vaporization load by the particle trap described later. It is preferable to arrange a vaporizing member made of a material having good thermal conductivity. In addition, inside the vaporization unit, particles based on the residue generated when the raw material liquid is vaporized are not discharged out of the vaporization unit, and a small amount of liquid droplets are not sucked out of the vaporizer by vacuum. In order to be able to vaporize, a particle trap may be provided. In this vaporization member and particle trap, appropriate droplets and fine liquid particles that are in contact with these vaporizers can be properly vaporized, and appropriate vaporizer elements that are necessary for the reaction are not attached or captured. It is preferable that vaporization conditions are maintained at the temperature. As shown in FIG. 1, the vaporization system 7 has a raw material solvent D, the flow rate of which is controlled by a flow rate controller, introduced into the vaporization unit, vaporized by the vaporization unit, and this solvent gas is removed. You may be comprised so that it can make.

  As described above, the thin film manufacturing apparatus used in the present invention preferably has a cylindrical reaction chamber 2, and a cylindrical substrate on which a substrate such as a silicon wafer is placed inside the reaction chamber. A stage 2-1 is provided. The substrate stage incorporates a heating means for heating the substrate. Further, the reaction chamber 2 may include means for configuring the substrate stage 2-1 to be movable up and down between the film formation position of the reaction chamber and the substrate transfer position below the reaction chamber. A gas head 3 is provided in the central portion on the upper side of the reaction chamber 2 so as to face the substrate stage 2-1, so that the film forming gas from which particles are removed is ejected from the gas head 3 toward the central portion of the substrate. It is configured.

  Incidentally, when a thin film is produced on a substrate by a CVD method such as the MOCVD method, when the source gas is lowered below a certain temperature, the source gas is precipitated as particles, which may cause film formation dust in the reaction chamber. Therefore, conventionally, a heat exchanger, which is a gas temperature adjusting means, is provided in the reaction gas pipe, and the outer wall of the reaction chamber 2 and the substrate stage 2-1 are heated by a heater or the like in order to prevent the deposition of the source gas. Means are provided.

  Next, in order to reduce the number of particles, film formation is performed by introducing a film forming gas into the reaction chamber through a shower head having a structure in which a large-diameter disk type filter of 200 mmφ or more is attached to the primary side of the shower head. An explanation will be given with reference to the apparatus of FIG. 2 about forming a film in such a manner that an inert gas flow is performed in the exhaust direction along the side wall of the reaction chamber from above the reaction chamber to maintain the low particle number state. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.

In this apparatus, a particle trap P1 as a filter for capturing particles present in the film forming gas is disposed in a gas head 3 provided in the upper part of the reaction chamber 2. This particle trap is provided immediately before the shower hole of the gas head, and is appropriately adjusted to a temperature at which specific vaporized raw material elements necessary for the reaction are not attached and trapped.
Further, as shown in FIG. 2, an inert gas gas ring is provided around the gas head 3 in the upper part of the reaction chamber so that an inert gas or the like can be flowed in order to maintain a low particle number state. Gas flow means 2-3 is provided.

  A valve V4 is provided in the pipe 10 for flowing an inert gas to the gas flow means 2-3 provided around the gas head. A gas source (for example, an inert gas source: a reactive gas source) is connected to one end of the pipe via a heat exchanger 11 and then two flow control systems, and the other end is connected to the other end. Is connected to the reaction chamber 2. A gas pipe connected to the film forming gas pipe 4 may be connected to an arbitrary portion of the pipe 10. Therefore, since it is possible to flow an inert gas or a reaction gas or a mixed gas of an inert gas and a reaction gas in an arbitrary ratio into the reaction chamber 2, the reaction chamber is inert in the exhaust direction along the inner wall thereof. The gas can flow evenly, maintain a low particle state, and the reaction gas temperature rise or inert gas temperature rise corresponding to the process / substrate or the mixed gas temperature rise of any ratio of inert gas and reaction gas Is possible. Further, at the time of non-film formation, the inert gas or the reaction gas or a mixed gas of an inert gas and a reaction gas in an arbitrary ratio and the pressure adjusting valve 1a are used to react even when the substrate is transported or when the temperature is raised. The indoor pressure can always be kept constant at the same pressure as during film formation.

Therefore, the substrate temperature change due to the pressure change is small and stable film formation can be performed, and the stress to the film due to the pressure change can be reduced, and the peeling of the film formed on the high temperature part such as the substrate stage 2-1 is suppressed. The maintenance cycle can be extended.
Similarly to the above, the reaction gas pipe connected to the mixer 5 is also connected to the reaction gas source and the inert gas source together with the flow rate control system. At the time of film formation, only the reaction gas or the reaction gas and the inert gas are inert. The gas can be introduced into the mixer at an arbitrary ratio, and the raw material gas can be uniformly mixed in the mixer.

  Further, when a heating means is incorporated in the substrate stage 2-1 to heat the substrate to a predetermined temperature, heat convection may occur above the substrate, but the inertness injected from the gas flow means 2-3. Due to the forced rectification action of the gas, the exhaust gas exhausted into the lower space through the gap between the sleeve member 2-2 and the inner wall surface of the reaction chamber 2 is more reliably discharged from the periphery of the sleeve member 2-2. Isotropic exhaust will be possible. Thereby, turbulent flow, convection and thermal convection in the upper space can be prevented.

  In the case of the thin film manufacturing apparatus shown in FIG. 2, as described above, in order to adjust the temperature of the inert gas ejected from the inert gas flow means 2-3 so that the source gas does not precipitate as particles in the MOCVD method. The gas pipe 10 is provided with a heat exchanger 11 which is a temperature adjusting means.

1 and 2 described above, an organic metal compound containing Pt, Ir, Ru or the like as a raw material source, for example, Pb (DPM) ₂ , Zr (DMHD) ₄ , Ti (i− CVD deposition of the ferroelectric film PZT using PrO) ₂ (DPM) ₂ , CVD film formation in which additive elements such as La, Sr, Ca, Al, etc. are added to this PZT, and Ba (DPM) as a liquid source ₂ , Sr (DPM) ₂ , Ti (i-PrO) ₂ (DPM) ₂ can be used for CVD formation of the ferroelectric film BST and mainly used for metal wiring such as Cu and Al Thin films, thin films mainly used for barriers such as TiN, TaN, ZrN, VN, NbN, Al ₂ O ₃ , and other dielectric thin films such as SBT, STO, etc., and La, Sr, Ca, Al Films with added elements such as It can be produced.

  Hereinafter, an example in which a metal oxide thin film is formed by MOCVD using the thin film manufacturing apparatus shown in FIG. 1 will be described.

In this embodiment, an example of manufacturing a ferroelectric PZT thin film by MOCVD will be described.
In the case of mixing PZT source gas and oxygen gas (O ₂ ), which is a reaction gas, raw materials A, B, and C (each source material is a combination of three types of organometallic compounds each containing Pb, Zr, and Ti) And the set flow rate, reaction gas, carrier gas, substrate temperature, reaction chamber pressure, and other conditions were as follows.

(Raw material) (Concentration) (Set flow rate)
A:
Pb (thd) ₂ / THF 0.3mol / L 0.5mL / min
Zr (dmhd) ₄ / THF 0.3mol / L 0.5mL / min
Ti (i-PrO) ₂ (thd) ₂ / THF 0.3mol / L 0.5mL / min
Flash solvent: THF (tetrahydrofuran) 0.5ml / min

B:
Pb (thd) ₂ / CHX 0.3mol / L 0.5mL / min
Zr (dmhd) ₄ / THF 0.3mol / L 0.5mL / min
Ti (i-PrO) ₂ (thd) ₂ / THF 0.3mol / L 0.5mL / min
Flash solvent: CHX (cyclohexane) 0.5ml / min

    C:
        Pb (thd)₂/ ECHX                 0.3mol / L 0.5mL / min
        Zr (MMP)_Four/ ECHX                0.3mol / L 0.5mL / min
        Ti (MMP)_Four/ ECHX 0.3mol / L 0.5mL / min
      Solvent for flash: ECHX (ethylcyclohexane) 0.5ml / min

Reaction gas (O ₂ ) flow rate: 1250sccm
Carrier gas (N ₂ ): 300sccm

Substrate temperature: 160 to 310 ° C. (However, the original film formation temperature is about 500 to 650 ° C., but in this embodiment, it was performed at this substrate temperature. This is because the number of particles is reduced when film formation occurs on the substrate. (Because it cannot be measured, it was set at a temperature at which no film was formed. This low temperature side is determined by an increase in deposition on the substrate.)
Reaction chamber pressure: 668 Pa
Substrate: 8 inch Si substrate

  The film forming pressure was always adjusted to about 5 Pa using a pressure adjusting valve, an inert gas, a reactive gas, or the like. Moreover, the temperature of the film formation chamber (reaction chamber), the vaporizer, and each pipe was heated and maintained at 250 ° C. The substrate (wafer) was maintained at 160 to 310 ° C. by heating the substrate stage on which it was placed. Further, a reaction gas of 1250 sccm was flowed in advance into the film formation chamber, and the pressure was adjusted to 668 Pa with APC.

Using the apparatus shown in FIG. 1, a particle experiment was conducted as follows, and the relationship between the substrate temperature and the number of particles was examined.
First, a substrate was placed in each film formation chamber, and each of the above flash solvents was flushed for 5 minutes. This flushing process was repeated using three substrates. The third substrate is a flushing confirmation substrate. If the number of particles on the substrate is 50 or less, it is determined that the flushing is completed, and the process proceeds to the next step. In this case, when it exceeded 50, flushing was continued until it became 50 or less.

  Next, for each of the raw materials A, B, and C, a gas obtained by vaporizing each constituent component was independently flowed for 5 minutes to form a film. This film forming process was repeated using three substrates. The third substrate is a measurement substrate. This film forming process was repeated for all components under the same film forming conditions. In this case, each component of each liquid raw material is introduced into the vaporization system from the raw material supply unit consisting of a cylinder containing the liquid raw material, vaporized, and the vaporized raw material gas is transported into the mixer, Then, it was mixed with the reaction gas, introduced into a substrate placed in the reaction chamber through a shower head, and formed into a film. In addition, the path from the vaporization system such as the vaporizer other than the substrate stage surface to the exhaust system is temperature controlled at 250 ° C. where precipitation (recrystallization) or decomposition (film formation) does not occur in the oil circulation system or block heater. did. The results thus obtained are shown in FIGS.

  3 to 5, the horizontal axis represents the substrate temperature when each raw material component is flowed, and the vertical axis represents the number of particles (0.2 μm or more) at that time. As the substrate temperature is changed, the number of particles changes, and it can be seen that the number of particles has a minimum at a certain substrate temperature.

  The appearance of particles is roughly divided into three. The first is particles that flow before the source gas reaches the substrate, especially from the upstream side of the shower head. Second, when the source gas reaches the substrate, the temperature of the substrate is low, so This is a case where precipitation has occurred and it has become particles, and third, when the source gas reaches the substrate, the substrate temperature is high, so that decomposition occurs on the spot and the film generated thereby or This is a case where powder is detected as particles. Originally, since the substrate temperature is maintained at a high temperature (typically 500 ° C. or higher) at which film formation occurs, the first and third cases are dominant. However, in this experiment, it was not the “decomposed membrane” but the powder flowing from the upstream, so we focused only on the first origin. In addition, it is not preferable that the substrate temperature is low and precipitation occurs there.

Table 1 shows the vaporization temperature and decomposition temperature of the raw materials used in this experiment.

In Table 1, the vaporization temperature is the temperature at the time of 50% vaporization in an inert gas atmosphere vacuum, and the decomposition temperature is the temperature at which the thermal decomposition proceeds 50%. From Table 1, it can be seen that when Ti (i-PrO) ₂ (thd) ₂ is taken as an example, the raw material vaporized at 150 ° C. decomposes at 210 ° C. The results obtained in this experiment, which has a minimum number of particles to be measured, are the reproduction of the precipitation phenomenon below the vaporization temperature and the decomposition / film formation phenomenon above the decomposition temperature by changing the substrate temperature. It can be said that the value is close to the true number of particles to be detected upstream from the shower head.

FIG. 6 shows a comparison of the minimum number of particles in each raw material / solvent measured above. As is clear from FIG. 6, when the number of extremely small particles is compared, the number of particles in B and C is smaller than that in source system A in any source gas (source gas containing Pb, Zr, and Ti, respectively). I understand that.
FIG. 7 shows the sum of the minimum particles of each source gas compared to each source system. As can be seen from FIG. 7, the number of particles decreases in the order of the raw material system A → the raw material system B → the raw material system C.

  Since the solvents used in the raw material systems A, B, and C are different, the above result may reflect the value of the number of particles of the solvent itself, so that only the solvent used in each raw material system is flowed, and the substrate FIG. 8 shows the results when the experiment was conducted while changing the temperature in the same manner. As is clear from FIG. 8, the result of the number of particles by the raw material gas described above is not caused by the result of the particles of the solvent used, but is determined by the nature of the raw material itself or some interaction between the raw material and the solvent. Is suggested.

  The film formation process described in Example 1 was performed except that the raw material gas introduced into the reaction chamber was flowed into the reaction chamber by vaporizing three types of constituent materials constituting each of the raw materials A, B, and C at the same time. Repeatedly, a PZT thin film was produced on the substrate.

  FIG. 9 shows the relationship between the substrate temperature and the number of particles during the film formation, and FIG. 10 shows a comparison of the minimum number of particles in each raw material system. In FIG. 9, the horizontal axis represents the substrate temperature when each source gas flows, and the vertical axis represents the number of particles (0.2 μm or more) at that time. As the substrate temperature is changed, the number of particles changes, and it can be seen that the number of particles has a minimum at a certain substrate temperature.

  When FIG. 7 and FIG. 10 are compared, almost the same result is obtained. This indicates that even when the flow particles of each unit cannot be seen with a cocktail solution or the like, for example, this particle measurement method in which the substrate temperature is varied can be used.

  In this example, the film forming process described in Example 1 was repeated for the raw material system B and the raw material system C in the particle measurement method described in Example 1 in order to determine the substrate temperature and derive the optimum piping temperature.

  In this film forming process, the substrate temperature was set in advance to a temperature at which particles were minimized in each of the constituent components of the raw material systems B and C obtained in Example 1. Next, a film was formed by sequentially changing the temperature of the piping between the vaporizer and the reaction chamber from 180 ° C. to 280 ° C. The relationship between the piping temperature and the number of particles obtained is shown in FIG. 11 (raw material system B) and FIG. 12 (raw material system C).

  As is clear from these figures, in the raw material system B and the raw material system C, the total number of particles of the three components is minimized by controlling the piping temperature between 210-270 ° C. and 190-250 ° C., respectively. Can be made.

  The following experiment was conducted using the MOCVD apparatus of FIG. 2 in which a filter and an inert gas flow means were provided in the apparatus of FIG. As a result, particle reduction was further achieved.

  The apparatus of FIG. 2 in which only a large-diameter (250 mmφ) disk type filter as a particle trap is provided on the primary side of the shower head in the gas head 3 provided in the upper part of the reaction chamber 2 is used. The film formation process of Example 1 was performed using the raw material system B. For comparison, a similar film formation process was performed using the apparatus of FIG. 1 without a filter. As shown in FIG. 13, the number of particles generated using the raw material system B is reduced by the apparatus provided with the filter, and the average number of particles in the case of the Ti-containing raw material with the largest amount is 50 or less on average. I was able to suppress it.

  Next, only the inert gas flow means 2-3 for introducing the inert gas evenly into the reaction chamber along the inner wall surface of the reaction chamber 2 is used in addition to the apparatus of FIG. Then, the film forming process of Example 1 was performed. Due to the action of an inert gas that flows down along the reaction chamber side wall through this means 2-3 in the exhaust direction, for example, 1000 sccm of nitrogen did not flow down, as shown in FIG. Compared to the case, no increase in the number of particles was observed even when 1000 wafers were continuously processed, and no increase in the number of particles was observed when the number exceeded 1000. However, when the flow did not flow down, an increase in the number of particles was observed when the number exceeded about 600 to 700 sheets.

  Since the thin film manufacturing method and the particle number evaluation method of the present invention can actually reduce particles, it can be effectively used in a film forming process by a CVD method in the semiconductor industry where miniaturization is progressing.

1 is a schematic arrangement / configuration diagram of a first apparatus for carrying out a thin film manufacturing method according to the present invention. The schematic arrangement | positioning / block diagram of the 2nd apparatus for enforcing the thin film manufacturing method concerning this invention. The graph which shows the relationship between the substrate temperature when the component of the raw material A is flowed using the apparatus of FIG. 1, and the number of particles. The graph which shows the relationship between the substrate temperature when the component of the raw material B is flowed using the apparatus of FIG. 1, and the number of particles. The graph which shows the relationship between the substrate temperature when the component of the raw material C is flowed using the apparatus of FIG. 1, and the number of particles. The graph which shows the number of the minimum particles of each component of each of raw material system A, B, C when the apparatus of FIG. 1 is used. The graph which shows the sum of the minimum particle number of each component of each of the raw material system A, B, and C when using the apparatus of FIG. The graph which shows the relationship between the substrate temperature and the number of particles when only the solvent used by raw material system A, B, and C is flowed using the apparatus of FIG. FIG. 2 is a graph showing the relationship between the substrate temperature and the number of particles when a material obtained by simultaneously vaporizing the constituent components of the raw material systems A, B, and C is flowed using the apparatus of FIG. 1. The graph which compares and shows the number of the minimum particles in raw material system A, B, C when the apparatus of FIG. 1 is used. The graph which shows the relationship between piping temperature when the component of the raw material system B is flowed using the apparatus of FIG. 1, and the number of particles. The graph which shows the relationship between the piping temperature when the component of the raw material system C is flowed using the apparatus of FIG. 1, and the number of particles. The graph which shows the number of particles when the raw material type | system | group B is flowed using the apparatus provided only with the filter in the apparatus of FIG. 2 compared with the case of the apparatus which is not equipped with a filter. FIG. 2 is a graph showing the number of wafers processed when each component of the raw material system B is flowed using an apparatus having only an inert gas flow means in the apparatus of FIG. 2 in comparison with an apparatus not equipped with this means. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum exhaust system 1a Pressure adjustment valve 2 Reaction chamber 2-1 Substrate stage 3 Gas head 4 Deposition gas piping 5 Mixer 6 Raw material gas piping 7 Evaporation system 7a Raw material supply part 8 Piping 9 Heat exchanger 10 Piping 11 Heat exchanger A, B, C Raw material liquid V1-V4 Valve P1 Particle trap

Claims (23)

  A film-forming gas consisting of a raw material gas and a reaction gas, which is obtained by evaporating a liquid obtained by dissolving a solid raw material or a liquid raw material in a solvent using a vaporization system, is introduced into a reaction chamber through a shower head and heated to a temperature higher than the decomposition temperature of the raw material gas. In a thin film manufacturing method using a CVD method for forming a film on a formed substrate, the temperature of a path from this system to the inside of the shower head at the top of the reaction chamber, including the vaporization system, is determined by vaporizing at least one of the raw materials. A method for producing a thin film, comprising forming a film at a temperature higher than the temperature and lower than the decomposition temperature.   2. The thin film manufacturing method according to claim 1, wherein the film is formed by setting the temperature of the path to a temperature at which the number of particles generated during the film forming process is minimized.   In claim 1 or 2, while gradually changing the substrate temperature in the temperature range from near the vaporization temperature of the single raw material to near the decomposition temperature, a film forming gas containing this raw material is flowed over the substrate at each temperature, A thin film manufacturing method characterized in that the film is formed by setting the temperature of the path at or near the temperature at which the number of particles generated on the substrate is minimized.   3. The film-forming gas containing each raw material at each temperature is changed to a substrate while the substrate temperature is stepped in a temperature range from near the vaporization temperature of each raw material to near the decomposition temperature. A method for producing a thin film, characterized in that the film is formed by setting the temperature of the path at or near the temperature at which the total number of raw material particles generated on the substrate at that time is minimized.   In claim 1 or 2, while gradually changing the substrate temperature in the temperature range from near the vaporization temperature of the plurality of raw materials to near the decomposition temperature, a film forming gas containing the plurality of raw materials is flowed on the substrate at each temperature, A thin film manufacturing method characterized in that the film temperature is set at or near the substrate temperature at which the number of particles generated on the substrate is minimized.   6. The method for producing a thin film according to claim 1, wherein the film is formed while maintaining the temperature of at least a part of the path within a range of ± 30 ° C. that is a temperature at which the number of particles is minimized. .   In any one of Claims 1-6, this raw material is from Pb, Zr, Ti, Ba, Sr, Ta, Bi, La, Ru, Ir, Ni, Mn, Pr, Si, Al, Hf, Mg, Ca. A thin film manufacturing method comprising at least one selected element.   8. The thin film manufacturing method according to claim 7, wherein the raw material is an organometallic compound. 9. The organometallic compound according to claim 8, wherein the organometallic compound is Pb (thd) ₂ ((bis (2,2,6,6) tetramethyl (3,5) heptanedionate) lead), Zr (thd) ₄ ((tetrakis (2,2,6,6) tetramethyl (3,5) heptanedionate) zirconium), Zr (dmhd) ₄ ((tetrakis (2,6) dimethyl (3,5) heptanedionate) zirconium), Ti (i-PrO) ₂ (thd) ₂ ((bisisopropoxide) (bis (2,2,6,6) tetramethyl (3,5) heptanedionate) titanium), Zr (MMP) ₄ ((tetrakis (1) at least one organometallic compound selected from methoxy (2) methyl (2) propoxy) zirconium), Ti (MMP) ₄ ((tetrakis (1) methoxy (2) methyl (2) propoxy) titanium) A method for producing a thin film, comprising: The thin film according to any one of claims 1 to 6, wherein when the raw material is Pb (thd) ₂ or Zr (dmhd) ₄ , the temperature of the path is set to 210 to 270 ° C. Production method. The thin film according to any one of claims 1 to 6, wherein when the raw material is Ti (i-PrO) ₂ (thd) ₂ , the film is formed by setting the temperature of the path to 180 to 240 ° C. Production method. The thin film manufacturing method according to claim 1, wherein when the raw material is Zr (MMP) ₄ , the film is formed at a temperature of 170 to 250 ° C. The thin film manufacturing method according to claim 1, wherein when the raw material is Ti (MMP) ₄ , the film is formed by setting the temperature of the path to 160 to 240 ° C. 7. The raw material according to claim 1, wherein the raw material is a plurality of raw materials consisting of Pb (thd) ₂ , Zr (dmhd) ₄ , and Ti (i-PrO) ₂ (thd) ₂ , or Pb (thd) ₂ , Zr. (MMP) _4, and Ti (MMP) are a plurality feedstock consisting of _4, to vaporize the plurality feedstock simultaneously, thin film characterized by depositing by setting the temperature of the pathway to 190 to 250 ° C. production Method.   15. The thin film manufacturing method according to claim 1, wherein at least one solvent selected from hexane, cyclohexane, ethylcyclohexane and methylcyclohexane is used as the solvent.   In any one of Claims 1-15, in order to reduce the number of particles, film-forming gas is injected into the reaction chamber through the shower head having a structure in which a large-diameter disk type filter of 200 mmφ or more is attached to the primary side of the shower head. A thin film manufacturing method characterized by introducing and forming a film.   The thin film according to any one of claims 1 to 16, wherein an inert gas flow is performed in the exhaust direction along the side wall of the reaction chamber from above the reaction chamber so as to maintain a low particle number state. Production method. A film-forming gas consisting of a raw material gas and a reaction gas, which is obtained by evaporating a liquid obtained by dissolving a solid raw material or a liquid raw material in a solvent using a vaporization system, is introduced into a reaction chamber through a shower head and heated to a temperature higher than the decomposition temperature of the raw material gas. In the method for evaluating the number of particles generated during transportation from the vaporization system to the reaction chamber when forming a film by CVD on a formed substrate,
(1) While gradually changing the substrate temperature from near the vaporization temperature of a single raw material to near the decomposition temperature, a deposition gas is flowed over the wafer at each temperature, and the number of particles on the wafer at that time is measured.
(2) A substrate temperature at which a minimum number of particles can be obtained is selected from the measured number of particles, and the number of particles at that temperature is being transported from the system into the reaction chamber including the vaporization system of the film forming gas. A method for evaluating the number of particles, characterized in that film formation is performed by setting the number of particles generated at a predetermined temperature and setting the transport route to this temperature. A deposition gas composed of a plurality of source gases and reaction gases obtained by vaporizing a liquid obtained by dissolving a solid source or a liquid source in a solvent using a vaporization system is introduced into a reaction chamber through a shower head, and exceeds the decomposition temperature of the source gas. In the method for evaluating the number of particles generated during transportation from the vaporization system to the reaction chamber when a film is formed on the substrate heated by the CVD method,
(1) For each source, the film forming gas containing each source gas is caused to flow on the wafer at each temperature while the substrate temperature is gradually changed from around the vaporization temperature of each source to near the decomposition temperature. Measure the number of particles
(2) The temperature at which the minimum number of particles is obtained is selected from the total number of particles measured for each raw material, and the number of particles at that temperature is transferred from this system into the reaction chamber including the vaporization system for the film forming gas. A method for evaluating the number of particles, characterized in that the number of particles generated during transportation is set, and the film is formed by setting the transportation route to this temperature. A deposition gas composed of a plurality of source gases and reaction gases obtained by vaporizing a liquid obtained by dissolving a solid source or a liquid source in a solvent using a vaporization system is introduced into a reaction chamber through a shower head, and exceeds the decomposition temperature of the source gas. In the method for evaluating the number of particles generated during transportation from the vaporization system to the reaction chamber when a film is formed on the substrate heated by the CVD method,
(1) A plurality of raw materials are vaporized at the same time, and a film-forming gas containing the plurality of raw material gases is allowed to flow over the wafer at each temperature while gradually changing the substrate temperature from near the vaporization temperature of the raw materials to near the decomposition temperature. Measure the number of particles on the wafer,
(2) The temperature at which the measured number of particles is minimized is selected, and the number of particles at that temperature is set as the number of particles generated during transportation from this system into the reaction chamber, including the vaporization system of the film forming gas, A method for evaluating the number of particles, characterized in that film formation is performed with the transport route set to this temperature.   In any one of Claims 18-20, this raw material is from Pb, Zr, Ti, Ba, Sr, Ta, Bi, La, Ru, Ir, Ni, Mn, Pr, Si, Al, Hf, Mg, and Ca. A method for evaluating the number of particles, comprising at least one selected element.   The particle number evaluation method according to claim 21, wherein the raw material is an organometallic compound. 23. The organic metal compound according to claim 22, wherein the organometallic compound includes Pb (thd) ₂ , Zr (thd) ₄ , Zr (dmhd) ₄ , Ti (i-PrO) ₂ (thd) ₂ , Zr (MMP) ₄ , Ti (MMP). ) A method for evaluating the number of particles, which is at least one organometallic compound selected from ₄ .

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