JP2008182183A - Film forming method using atomic layer deposition method and its film forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply atomic layer deposition (ALD) methods to various film formations to improve throughput, and to miniaturize a device simultaneously. <P>SOLUTION: The film forming method using the atomic layer deposition (ALD) method is characterized in that a liquid raw material composed of an organic metal compound is directly jetted into a film forming chamber 2 holding a substrate W therein by a liquid raw material jetting valve 41. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film forming method and a film forming apparatus using an atomic layer deposition (ALD) method.

  In recent years, an atomic layer growth (ALD) method has attracted attention as one of film formation methods used for semiconductor devices and the like. As a film forming apparatus using such a film forming method, for example, as shown in Patent Document 1, a high vapor pressure film forming raw material is vaporized and supplied into a film forming chamber and adsorbed on a substrate surface. A film is formed by stacking atoms by supplying an oxidant gas or a nitriding agent gas to oxidize or nitride a film forming material adsorbed on the surface of the substrate and repeating the process.

  However, there is a problem that the types of thin films that can be formed by the ALD method are limited to those using a film forming material having a high vapor pressure.

  In addition, a vaporizer is required for a supply pipe for supplying a liquid raw material, and the raw material supply pipe to the film formation chamber must be maintained at a high temperature. There is a problem that the cost increases.

Further, when a film forming material having a low vapor pressure is used even if the property is a solid film forming material or liquid at room temperature, the time for supplying the vaporized film forming material into the film forming chamber is long (several seconds to several tens of hours). Second), and the throughput is degraded.
JP 2005-347446 A Yohei Tamaya, 3 others, "Preparation of Ferroelectric PZT Thin Films by Liquid Supply MOCVD Using New Lead Precursor-Containing Cocktail Raw Material" Proceedings of the 52nd Applied Physics Related Joint Lecture, Japan Society of Applied Physics p. 653 30a-P2-6

  Therefore, the present invention has been made to solve the above-mentioned problems all at once, making it possible to apply the atomic layer growth method to various film formation and to improve the throughput, and at the same time to reduce the size of the apparatus. Realization is the main desired issue.

  That is, the film forming method using the atomic layer growth method according to the present invention is characterized in that a liquid material made of an organometallic compound is directly injected by an injection valve into a film forming chamber that holds a substrate inside.

  In such a case, since the liquid raw material is directly injected into the film forming chamber by the injection valve and the liquid raw material is vaporized by boiling under reduced pressure, it is not limited to the film forming raw material having a high vapor pressure, and various raw materials can be used. The film can be formed by the ALD method. In addition, since the vaporization is instantaneously performed using the injection valve, the deposition throughput can be improved. Furthermore, a heater for heating the raw material supply pipe is not necessarily required, and the apparatus can be downsized. Moreover, not only can many liquid raw materials be rapidly vaporized within a short time, but also the amount of liquid raw material to be vaporized and the processing time can be accurately controlled. Therefore, it becomes possible to form a film at high speed with high reproducibility by using the ALD method.

  In particular, in the method of directly spraying the liquid raw material, the sprayed liquid raw material may reach the substrate without being vaporized in the form of a mist, and there is a problem that the yield decreases, but a self-organized single atomic layer is formed. In the ALD method for forming a film, by introducing an inert gas, excess precursor is purged, and film formation can be performed at high speed and with good reproducibility without causing the problem.

  In order to precisely oxidize or nitride the raw material adsorbed on the substrate surface, it is desirable to inject a liquid oxidizing agent or nitriding agent directly into the film forming chamber by an injection valve.

In particular, when a composite metal oxide thin film is formed, a “vaporizer”, a “gas supply line”, and a “raw material container” are required for each constituent metal, and there is a problem that the film forming apparatus becomes complicated and large. In order to solve this problem, as shown in Non-Patent Document 1, in the CVD method, a composite metal oxide thin film (Pb (ZrTi) O ₃ ) is formed using a cocktail solution. However, when the deposition conditions (substrate temperature, deposition chamber pressure, etc.) change, the reaction rate of the chemical reaction varies from raw material to raw material, so the composition ratio of the composite metal oxide thin film changes, and reproducible growth is achieved. There is a problem that the film cannot be formed.

  Even if the liquid raw material is a mixed solution composed of two or more kinds of organometallic compounds, the ALD method for surface adsorption can form a film more reliably and accurately with a mixed composition ratio regardless of the chemical reaction rate. The composition ratio can be controlled.

  In order to make it possible to use an organometallic compound that is solid or liquid at room temperature (particularly a liquid having a low vapor pressure) for the atomic layer growth method, the liquid raw material is a solid or liquid organic material at room temperature. A mixed solution in which a low-boiling organic compound is mixed with a metal compound is desirable.

For example, the organometallic compounds that are solid or liquid at room temperature include tetrakisdimethylaminohafnium (Hf [N (CH ₃ ) ₂ ] ₄ , TDMAHf), tetrakisdiethylaminohafnium (Hf [N (C ₂ H ₅ ) ₂ ] ₄ , TDEAHf ), Tetrakismethylethylaminohafnium (Hf [N (CH ₃ )
_{(C 2 H 5)] 4} , TEMAHf), tetrakis (dimethylamino) zirconium _{(Zr [N (CH 3)} 2] 4, TDMAZr), tetrakis (diethylamino) zirconium _{(Zr [N (C 2 H} 5) 2] 4, TDEAZr) , Tetrakismethylethylaminozirconium (Zr [N (CH ₃ )
Amine-based organometallic compounds such as (C ₂ H ₅ )] ₄ , TEMAZr) can be mentioned. As the low boiling point organic compound may be a compound or a benzene represented by C _{X H} 2X _{+ 2} such as pentane or hexane.

  In addition, a film forming apparatus using the atomic layer growth method according to the present invention includes a film forming chamber that holds a substrate inside, and a first supply mechanism that directly injects a liquid source composed of an organometallic compound into the film forming chamber. A second supply mechanism for supplying an oxidizing agent or a nitriding agent into the film formation chamber, a purge gas supply mechanism for supplying a purge gas for purging the film formation chamber, the first supply mechanism, the second supply mechanism, and the purge gas. And a control device that controls the supply mechanism so that a film formed by atomic layer growth is formed on the substrate.

  According to the present invention configured as described above, the atomic layer growth method can be applied to various film formations by adopting two or more kinds of precursors and the throughput can be improved. Can be realized.

<First Embodiment>
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a film forming apparatus 1 according to this embodiment.

The film forming apparatus 1 according to the present embodiment uses an atomic layer growth method for forming a hafnium oxide (HfO ₂ ) film on a silicon substrate W (for example, a thickness of 0.5 mm) that is a processing target substrate. As shown in FIG. 1, a film forming apparatus, a film forming chamber 2 that holds a substrate W therein, a temperature adjusting mechanism 3 that is provided in the film forming chamber 2 and adjusts the temperature of the silicon substrate W, As a first precursor, a first supply mechanism (hereinafter referred to as a liquid source supply mechanism) 4 that directly injects a liquid source composed of an organometallic compound into the film forming chamber 2, and as a second precursor, an oxidation source A second supply mechanism (hereinafter referred to as an oxidant supply mechanism) 5 for directly injecting the agent into the film forming chamber 2, a purge gas supply mechanism 6 for supplying a purge gas for purging the film forming chamber 2, A pressure adjusting mechanism 7 for adjusting the pressure in the film forming chamber 2, a liquid material supply mechanism 4, an acid Agent supply mechanism 5 and the purge gas supply mechanism 6 and the like, and a, a control unit 8 for controlling so that a film is formed by atomic layer deposition on the silicon substrate W.

In the present embodiment, for example, tetradiethylaminohafnium (Hf [N (C ₂ H ₅ ) ₂ ] ₄ , TDEAHf) is used as the liquid material, and water (H ₂ O) is used as the oxidant.

  Each part 2-8 is demonstrated below.

  The film formation chamber 2 holds, for example, a silicon substrate W as a processing target substrate horizontally inside a holding mechanism (not shown), and a temperature control mechanism such as a substrate heater for adjusting the temperature of the silicon substrate W. 3 is provided. The film forming chamber 2 is decompressed to a predetermined pressure (for example, about 13 Pa (0.1 Torr)) by the vacuum pump 71 of the pressure adjusting mechanism 7.

The substrate heater 3 which is a temperature control mechanism is controlled by the control device 8 so that the temperature of the silicon substrate W is kept constant at a high temperature of about 150 ° C. to about 250 ° C. Thus, since the silicon substrate W is maintained at about 150 to 250 ° C., the raw material (Hf [N (C ₂ H ₅ ) ₂ ] ₄ ) adsorbed on the silicon substrate W is not decomposed and is in a liquid state. The raw material can be re-evaporated and excess precursor can be discharged with a purge gas.

The liquid raw material supply mechanism (first supply mechanism) 4 supplies the liquid raw material injection valve (first injection valve) 41 and the liquid raw material (Hf [N (C ₂ H ₅ ) ₂ ] ₄ ) to the injection valve 41. A liquid raw material supply pipe 42 and a liquid raw material container 43 are provided.

  The liquid material injection valve 41 is attached to the wall (for example, the upper wall) of the film formation chamber 2 so as to face the silicon substrate W, and directly injects the liquid material into the film formation chamber 2.

  Here, “direct injection” means that the liquid material injected from the injection valve is directly injected into the space in the film forming chamber 2.

  The injection valve 41 in the present embodiment is an electromagnetic valve, and as shown in FIG. 2, a main body 411, a solenoid 412 built in the main body 411, and an injection port 411 A is opened and closed by electromagnetic induction of the solenoid 412. And is controlled by the control device 8. Then, the vicinity of the injection port 411A of the main body 411 is heated to, for example, about several tens of degrees Celsius (somewhat higher than room temperature) using the heater 414. FIG. 2 shows a state where the injection port 411A is closed.

  The valve body 413 is located in the internal space 411B of the main body portion 411 and is urged toward the injection port 411A by the spring 415 to close the injection port 411A. An annular flange 4131 and an annular shape are formed at the tip portion 413A. A groove 4132 is formed.

  Thus, since the electromagnetic valve is used as the injection valve 41, it becomes easy to accurately control the injection amount of the liquid raw material to be injected.

  Then, by this liquid source supply mechanism 4, the liquid source is pumped through the liquid source supply pipe 42 by the pressurized Ar gas press-fitted into the liquid source container 43, and the inside of the film forming chamber 2 through the liquid source injection valve 41. To be supplied. Further, the liquid material is directly injected into the film forming chamber 2 from the liquid material injection valve 41, and at the same time, a vacuum boiling phenomenon occurs and is vaporized to fill the film forming chamber 2. The “reduced pressure boiling phenomenon” refers to a phenomenon in which the liquid boils and vaporizes when the external pressure of the opened liquid becomes smaller than the vapor pressure. The film forming apparatus 1 of the present embodiment uses this reduced pressure boiling phenomenon. By utilizing the pressurized liquid material into the film forming chamber 2 decompressed by the vacuum pump 71, a predetermined amount of the liquid material is instantly vaporized with a minimum amount of heat.

  The oxidant supply mechanism (second supply mechanism) 5 includes an oxidant injection valve (second injection valve) 51, an oxidant supply pipe 52 for supplying a liquid oxidant to the injection valve 51, and an oxidant container. 53.

  Similar to the liquid source injection valve 41, the oxidant injection valve 51 is attached to the wall (for example, the upper wall) of the film formation chamber 2 so as to face the silicon substrate W, and the liquid oxidant is formed in the film formation chamber 2. (Water) is directly injected. The configuration of the oxidant injection valve 51 is the same electromagnetic valve as the liquid raw material injection valve 41.

  The oxidizing agent supply mechanism 5 pumps the oxidizing agent through the oxidizing agent supply pipe 52 by the pressurized Ar gas press-fitted into the oxidizing agent container 53, and passes through the oxidizing agent injection valve 51 to form the inside of the film forming chamber 2. To be supplied. Further, the oxidant is directly injected into the film forming chamber 2 from the oxidant injection valve 51, and at the same time, a vacuum boiling phenomenon occurs and is vaporized to fill the film forming chamber 2.

  The purge gas supply mechanism 6 includes a purge gas supply pipe 61 for supplying argon (Ar) gas, which is a purge gas, into the film forming chamber 2, and a purge gas introduction valve 62 (hereinafter referred to as “introduction valve 62”) provided on the supply pipe 61. ), A purge gas bypass valve 63 (hereinafter abbreviated as “bypass valve 63”), and a mass flow controller (MFC) 64 for controlling the flow rate of the purge gas. The mass flow controller 64 is controlled by the control device 8 so that the flow rate becomes, for example, 500 ml / min.

  The control device 8 controls the operation of each of the mechanisms 3 to 7 so that a thin film is formed by atomic layer growth on the silicon substrate W. The device configuration includes a CPU, an internal memory, and an input device. A general-purpose or dedicated computer equipped with an output interface, an AD converter, and the like. More specifically, the control device 8 controls the liquid raw material injection valve 41, the oxidant injection valve 51, the introduction valve 62, the bypass valve 63, the substrate heater 3, the vacuum pump 71, and the like.

  Below, the control function of the control apparatus 8 is demonstrated with the film-forming method.

  First, in the state before the start of film formation, as shown in FIG. 3, the liquid material injection valve 41 and the oxidant injection valve 51 are “closed”, and the bypass valve 63 is “open”. Yes, the introduction valve 62 is “closed”.

<Step Sa1: Liquid raw material supply step>
As shown in FIG. 3, the control device 8 opens and closes the liquid material injection valve 41 for about 2 msec. At this time, the liquid material is supplied into the film forming chamber 2. A part of the liquid raw material is vaporized and adsorbed on the surface of the silicon substrate W to form a single atomic layer by an adsorption reaction or a substitution reaction (right side of FIG. 4A).

  On the other hand, the raw material in a mist state (that is, a liquid body) adheres to the silicon substrate W (left side in FIG. 4A). Here, since the inside of the film forming chamber 2 is under reduced pressure and the substrate temperature is about 150 to 250 ° C., the materials other than the film forming raw material which is an organometallic compound in contact with the surface of the substrate W are evaporated, and the substrate W The film forming raw material remaining on the surface forms a single atomic layer by an adsorption reaction or a substitution reaction. Further, the film forming raw material evaporated at this time is adsorbed again on the surface of the substrate W, and forms a single atomic layer by an adsorption reaction or a substitution reaction (see FIG. 4A).

Finally, the molecules of the film forming raw material (Hf [N (C ₂ H ₅ ) ₂ ] ₄ ) form a uniform single atomic layer on the outermost surface of the silicon substrate W.

<Step Sa2: Excess raw material discharging step>
Next, the control device 8 promotes re-evaporation of the liquid material while heating the substrate W, and closes the bypass valve 63 and opens the introduction valve 62 as shown in FIG. A purge gas composed of a gas is introduced to discharge excess liquid source gas remaining in the film forming chamber 2 (see FIG. 4B).

<Step Sa3: Oxidant supply step>
Next, as shown in FIG. 3, the control device 8 closes the introduction valve 62, then opens the bypass valve 63, and introduces the oxidizing agent (water) from the oxidizing agent injection valve 51 for about 5 msec. Thereby, the molecules of the film forming raw material adsorbed on the surface of the substrate W are hydrolyzed and oxidized (see FIG. 4C).

<Step Sa4: Excess oxidizing agent discharging step>
Next, as shown in FIG. 3, the control device 8 closes the bypass valve 63 and opens the introduction valve 62, introduces a purge gas, and surplus oxidant gas (water vapor) remaining in the film forming chamber 2. ) Is discharged (see FIG. 4D).

Film formation for one molecular layer is performed by one cycle of steps (step Sa1) to (step Sa4) for supplying the first precursor / purge gas / second precursor / purge gas, respectively. Then, when the above series of steps is repeated about 500 times, an HfO ₂ film having a film thickness of about 50 nm can be formed. The HfO ₂ film thus formed is used as a gate insulating film. In addition, each time of the above steps can be set to 1 second or less, and it is possible to supply a necessary amount of raw materials in a short time and to form a film with a much higher throughput than in the past.

  According to the film forming apparatus 1 according to the present embodiment configured as described above, the liquid raw material and the oxidant are directly injected into the film forming chamber 2 by the injection valves 41 and 51, and the liquid raw material and the oxidant are obtained by boiling under reduced pressure. Since it is vaporized, it is not limited to a film forming material having a high vapor pressure, and it can be formed by an ALD method using various film forming materials. Further, since the vaporization is instantaneously performed using the injection valves 41 and 51, the throughput of film formation can be improved. Furthermore, the heater for heating the raw material supply pipe is not required, and the film forming apparatus 1 can be downsized. Furthermore, the ability to vaporize and supply the liquid raw material with the minimum necessary heating can also contribute to the downsizing of the apparatus 1. In addition, many liquid raw materials and oxidizing agents can be quickly vaporized within a short time, and the amount of liquid raw material oxidizing agent to be vaporized and the processing time can be accurately controlled. Therefore, it becomes possible to form a film at high speed and with high reproducibility by using the atomic layer growth method.

  In particular, in the method of directly spraying the liquid raw material, the sprayed liquid raw material may reach the substrate W without being vaporized in a mist state, and the yield may be reduced, but the self-organized single atomic layer In the ALD method for forming a film, by introducing an inert gas, excess precursor is purged, and film formation can be performed at high speed and with good reproducibility without causing a problem.

Second Embodiment
Next, a film forming apparatus 1 according to a second embodiment of the present invention will be described with reference to the drawings.

A film forming apparatus 1 according to the present embodiment is a film forming apparatus using an atomic layer growth method for forming a tantalum niobium oxide (NbTaO ₅ ) film on a silicon substrate W, and the device configuration thereof is the first configuration. It is the same as that of embodiment, and a liquid raw material differs. That is, the liquid raw material of this embodiment is a mixed solution of pentaethoxyniobium (Nb (OC ₂ H ₅ ) ₅ ) and pentaethoxy tantalum (Ta (OC ₂ H ₅ ) ₅ ). The mixing composition ratio is Nb (OC ₂ H ₅ ) ₅ : Ta (OC ₂ H ₅ ) ₅ = 1: 1 (mol ratio).

  A film forming method using the film forming apparatus 1 configured as described above will be described.

  First, in the state before the start of film formation, the liquid source injection valve 41 and the oxidant injection valve 51 are “closed”, the bypass valve 63 is “open”, and the introduction valve 62 is “closed”. (Close) ".

<Step Sb1: Liquid Raw Material Supply Process>
As shown in FIG. 3, the control device 8 opens and closes the liquid raw material injection valve 41 for about 1.5 msec, and the mixed solution is supplied into the film forming chamber 2. At this time, a part of the mixed solution is vaporized and adsorbed on the surface of the silicon substrate W to form a single atomic layer by an adsorption reaction or a substitution reaction (see the right side of FIG. 5A).

  On the other hand, the mixed solution in a mist state (that is, a liquid body) adheres to the silicon substrate W (see the left side of FIG. 5A). Here, since the inside of the film forming chamber 2 is under a reduced pressure and the substrate temperature is about 150 to 250 ° C., the components other than the film forming raw material in contact with the surface of the substrate W evaporate and remain on the surface of the substrate W. The film material forms a single atomic layer by an adsorption reaction or a substitution reaction. Further, the mixed solution evaporated at this time is adsorbed again on the surface of the substrate W and forms a single atomic layer by an adsorption reaction or a substitution reaction.

  Eventually, the molecules of the mixed solution form a uniform monoatomic layer on the outermost surface of the silicon substrate W. The adsorbed atoms are Nb atoms made of pentaethoxyniobium and Ta atoms made of pentaethoxytantalum (see FIG. 5A).

<Step Sb2: Excess Raw Material Discharge Process>
Next, the control device 8 promotes re-evaporation of the mixed solution while heating the substrate W, and closes the bypass valve 63 and opens the introduction valve 62 to introduce the purge gas as shown in FIG. Excess mixed liquid gas remaining in the film forming chamber 2 is discharged (see FIG. 5B).

<Step Sb3: Oxidant supply step>
Next, as shown in FIG. 3, the control device 8 closes the introduction valve 62, then opens the bypass valve 63, and introduces water, which is an oxidizing agent, from the oxidizing agent injection valve 51 for about 5 msec. Thereby, the molecules of the mixed solution adsorbed on the surface of the substrate W are hydrolyzed and oxidized (see FIG. 5C).

<Step Sb4: Excess oxidizing agent discharging step>
Next, as shown in FIG. 3, the control device 8 closes the bypass valve 63 and opens the introduction valve 62, supplies a purge gas, and oxidant gas (water vapor) remaining in the film forming chamber 2. Is discharged (see FIG. 5D).

Film formation for one molecular layer is performed by one cycle of steps (step Sb1) to (step Sb4) for supplying the first precursor / purge gas / second precursor / purge gas, respectively. Then, when the above series of steps is repeated about 500 times, an NbTaO ₅ film having a film thickness of about 50 nm can be formed. The molar ratio of the mixed solution is directly reflected in the composition ratio of Nb metal and Ta metal at this time. That is, since this composition ratio is governed by the adsorption of atoms onto the substrate W, the composition ratio does not change depending on the chemical reaction rate even if the film formation conditions change.

Then, for example, when it is desired to form (Nb _1.5 Ta _0.5 ) O ₅ or the like, the molar ratio of the mixed solution is Nb (OC ₂ H ₅ ) ₅ : Ta (OC ₂ H ₅ ) ₅ = 3: 1. (Mol ratio) may be used. Thus, by changing the ratio of niobium (Nb) and tantalum (Ta) freely, that is, by changing the ratio of two or more film forming materials having different relative dielectric constants, the relative dielectric constant of the film is changed. As a thin film for a capacitor for DRAM, it is possible to obtain a beneficial effect that it can be designed freely (when Ta = 100%, the relative dielectric constant is about 25, and when Nb = 100%) The dielectric constant is 60.)

<Third Embodiment>
Next, a film forming apparatus according to a third embodiment of the present invention will be described with reference to the drawings.

A film forming apparatus 1 according to this embodiment is a film forming apparatus using an atomic layer growth method for forming a composite metal oxide thin film (for example, an HfAlO _x film) on a silicon substrate W, and is shown in FIG. As described above, the liquid material supply mechanism 4 includes a first liquid material supply mechanism 4A and a second liquid material supply mechanism 4B for each liquid material as each precursor. The structure of each mechanism 4A, 4B is the same as that of the liquid raw material supply mechanism 4 of the first embodiment.

The first liquid source is trimethylaluminum (Al (CH ₃ ) ₃ ), and the second liquid source is tetrakismethylethylaminohafnium (Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ , TEMAHf). is there.

  A film forming method using the film forming apparatus 1 configured as described above will be described.

  First, in the state before the start of film formation, as shown in FIG. 7, the first and second liquid source injection valves 41A and 41B and the oxidant injection valve 51 are “closed”, and the bypass valve 63 is “Open” and the introduction valve 62 is “closed”.

<Step Sc1: First liquid raw material supply step>
As shown in FIG. 7, the control device 8 opens and closes the first liquid material injection valve 41 </ b> A for about 2 msec, and the first liquid material is supplied into the film forming chamber 2. At this time, a part of the first liquid source is vaporized and adsorbed on the surface of the silicon substrate W to form a single atomic layer by an adsorption reaction or a substitution reaction (see the right side of FIG. 8A).

  On the other hand, the first liquid source in a mist state (that is, a liquid body) adheres to the silicon substrate W (see the left side of FIG. 8A). Here, since the inside of the film forming chamber 2 is under reduced pressure and the substrate temperature is about 150 to 250 ° C., the materials other than the film forming raw material which is an organometallic compound in contact with the surface of the substrate W are evaporated, and the substrate W The film forming raw material remaining on the surface forms a single atomic layer by an adsorption reaction or a substitution reaction. Further, the film-forming raw material evaporated at this time is adsorbed again on the surface of the substrate W, and forms a single atomic layer by an adsorption reaction or a substitution reaction.

  Finally, the atoms of the first liquid source form a uniform single atomic layer on the outermost surface of the silicon substrate W.

<Step Sc2: Excess Raw Material Discharge Process>
Next, as shown in FIG. 7, the control device 8 prompts the re-evaporation of the first liquid material while heating the substrate W, closes the bypass valve 63, opens the introduction valve 62, and introduces the purge gas. Then, excess gas of the first liquid source remaining in the film forming chamber 2 is discharged (see FIG. 8B).

<Step Sc3: Oxidant supply step>
Next, as shown in FIG. 7, the control device 8 closes the introduction valve 62, then opens the bypass valve 63, and introduces water, which is an oxidizing agent, from the oxidizing agent injection valve 51 for about 5 msec. Thereby, the molecules of the first liquid raw material adsorbed on the surface of the substrate W are hydrolyzed and oxidized (see FIG. 8C).

<Step Sc4: Excess oxidizing agent discharging step>
Next, as shown in FIG. 7, the control device 8 closes the bypass valve 63 and opens the introduction valve 62 to discharge excess oxidant gas (water vapor) remaining in the film forming chamber 2 ( (Refer FIG.8 (d)).

<Step Sc5: Second Liquid Material Supply Step>
Next, as shown in FIG. 7, the control device 8 opens and closes the second liquid material injection valve 41 </ b> B for about 2 msec, and the second liquid material is supplied into the film forming chamber 2. At this time, a part of the second liquid source is vaporized and adsorbed on the surface of the silicon substrate W (more specifically, on the oxide film of the first liquid source) to form a single atomic layer by an adsorption reaction or a substitution reaction. (See the right side of FIG. 8 (e)).

  On the other hand, the first liquid source in a mist state (that is, a liquid body) adheres to the silicon substrate W (more specifically, on the oxide film of the first liquid source) (see the left side of FIG. 8 (e)). Here, since the inside of the film forming chamber 2 is under reduced pressure and the substrate temperature is about 150 to 250 ° C., the materials other than the film forming raw material which is an organometallic compound in contact with the oxide film of the first liquid raw material are evaporated. The film-forming raw material remaining on the oxide film of the first liquid raw material forms a single atomic layer by an adsorption reaction or a substitution reaction. Further, the film forming material evaporated at this time is adsorbed again on the oxide film of the first liquid material, and forms a single atomic layer by an adsorption reaction or a substitution reaction.

  Finally, the molecules of the second liquid source form a single atomic layer on the surface of the oxide film of the first liquid source.

<Step Sc6: Excess Raw Material Discharge Process>
Next, as shown in FIG. 7, the control device 8 closes the bypass valve 63 to promote re-evaporation of the second liquid raw material, opens the introduction valve 62, introduces purge gas, and forms the film formation chamber 2. Excess second liquid source gas remaining inside is discharged (see FIG. 8F).

<Step Sc7: Oxidant Supply Step>
Next, as shown in FIG. 7, the control device 8 closes the introduction valve 62, then opens the bypass valve 63, and introduces water, which is an oxidizing agent, from the oxidizing agent injection valve 51 for about 5 msec. Thereby, the molecules of the second liquid source adsorbed on the surface of the substrate W (more specifically, the oxide film of the first liquid source) are hydrolyzed and oxidized (see FIG. 8G).

<Step Sc8: Excess oxidizing agent discharging step>
Next, as shown in FIG. 7, the control device 8 closes the bypass valve 63 and opens the introduction valve 62 to discharge excess oxidant gas (water vapor) remaining in the film forming chamber 2 ( (Refer FIG.8 (h)).

The first cycle and the third precursor (second liquid source) / purge gas / second supplying the first precursor (first liquid source) / purge gas / second precursor (oxidant) / purge gas, respectively. Film formation for one molecular layer is performed by the steps (Step Sc1) to (Step Sc8) of the second cycle in which the precursor (oxidant) / purge gas 4 is supplied. Then, when the above series of one cycle steps is repeated about 250 times, an HfAlO _x film having a film thickness of about 50 nm can be formed. The HfAlO _x film is used as a gate insulating film.

In the film forming method, the case where the HfO ₂ film thickness: Al ₂ O ₃ film thickness = 1: 1 and the Al amount is about 60% in the atomic ratio is shown. You can also

For example, if step Sc1 etc. are represented as (1) etc., “(1) (2) (3) (4)” → “(5) (6) (7) (8)” → “(5) ( 6) (7) (8) ”→“ (5) (6) (7) (8) ”→“ (1) (2) (3) (4) ”→“ (5) (6) (7) (8) ”→“ (5) (6) (7) (8) ”→“ (5) (6) (7) (8) ”, HfO ₂ film thickness: Al ₂ O ₃ film thickness = 3: 1, and an HfAlO _x film having an Al ratio of approximately 40% in the atomic ratio can be formed. Since this composition ratio is governed by the adsorption of the raw material to the substrate W, the composition ratio does not change even if the film formation conditions (for example, temperature, pressure, etc.) change.

<Fourth embodiment>
Next, the film-forming apparatus 1 which concerns on 4th Embodiment of this invention is demonstrated with reference to drawings.

A film forming apparatus 1 according to this embodiment is a film forming apparatus using an atomic layer growth method for forming a hafnium oxide (HfO ₂ ) film on a silicon substrate W as shown in FIG. The raw material and the oxidizing agent supply mechanism 5 are different. Further, argon (Ar) gas is used as the purge gas.

The liquid raw materials of the present embodiment are tetrakismethylethylaminohafnium (Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ , TEMAHf), which is an amine-based organometallic compound, and n-pentane, which is a low-boiling organic compound. It is a mixed solution with (nC ₅ H ₁₂ ). The mixed composition ratio is TEMAHf: n-pentane (nC ₅ H ₁₂ ) = 1: 9 (mol ratio).

As described above, since the liquid raw material is a mixed solution of TEMAHf and n-pentane (nC ₅ H ₁₂ ), as shown in FIG. 10, the saturated vapor pressure is increased by several tens of times compared to a solution containing only TEMAHf. be able to. It can be seen from FIG. 10 that the saturated vapor pressure increases as the molar ratio of n-pentane is increased. Further, in FIG. 10, X represents n-pentane (mol) / {n-pentane (mol) + TEMAHf (mol)}.

Further, the film forming apparatus 1 of the present embodiment uses oxygen (O ₂ ) gas as an oxidant, and unlike the first embodiment, the oxidant supply mechanism does not require the oxidant injection valve 51.

That is, the oxidant supply mechanism 5 of the present embodiment includes an oxidant supply pipe 501 that supplies oxygen (O ₂ ) gas, which is an oxidant gas, into the film forming chamber 2 as shown in FIG. An oxidant introduction valve 502, an oxidant bypass valve 503, and a mass flow controller (MFC) 504 for controlling the flow rate of the oxidant gas are provided. The mass flow controller 504 is controlled by the control device 8 so that the flow rate becomes a predetermined value. Further, the oxidant introduction valve 502 and the oxidant bypass valve 504 are also controlled by the control device 8.

  A film forming method of the film forming apparatus 1 configured as described above is shown in FIG. At this time, the liquid material injection valve 41 is opened and closed for about 5 msec. The opening / closing operations of the purge gas introduction valve 62 and the purge gas bypass valve 63 are the same as those in the first embodiment. The opening / closing operation of the oxidant introduction valve 502 is the same as that of the oxidant injection valve 51 of the first embodiment, and the opening / closing operation of the oxidant bypass valve 503 is opposite to that of the oxidant introduction valve 502. In this way, one molecular layer is formed by one cycle of supplying the first precursor / purge gas / second precursor / purge gas.

In this film forming apparatus 1, the pressure of pressurized helium gas is 0.4 to 0.5 MPa, the temperature of the silicon substrate W is about 150 ° C. to about 250 ° C., and the flow rate of oxygen (O ₂ ) gas as an oxidant gas is set. The pressure in the film formation chamber is 500 ml / min and the pressure is about 133 Pa (1 Torr). Under this situation, when the liquid source injection valve 41 is carried out for 120 seconds at a 1 Hz cycle, that is, when the above-described series of steps is repeated 120 times, an HfO ₂ film having a film thickness of about 12 nm can be formed. Further, the film forming speed at this time is about 6 nm / min.

According to the film forming apparatus 1 of the present embodiment configured as described above, an amine such as TEMAHf that has a low saturated vapor pressure (TEMAHf has a saturated vapor pressure of 133 Pa at 83 ° C. (356 K)) and is difficult to supply stably. The organic organometallic compound can be stably vaporized, and the reproducibility of the HfO ₂ film or the thin film containing HfO ₂ can be improved. This HfO ₂ film is used as a high-k material as a gate insulating film of a next-generation highly integrated LSI field effect transistor (FET) or a DRAM capacitor insulating film. Integrated LSI and DRAM can be stably produced with good reproducibility.

<Other modified embodiments>
The present invention is not limited to the above embodiment. In the following description, the same reference numerals are given to members corresponding to the above-described embodiment.

For example, in the first embodiment, tris (dipivaloylmethanato) lanthanum (La (C ₁₁ H ₁₉ O ₂ ) ₃ : solid at room temperature) is dissolved in acetone, which is a low-boiling organic compound, as a film forming raw material. By using it as a raw material, a lanthanum oxide (La ₂ O ₃ ) thin film having a thickness of about 50 nm can be formed. This thin film can also be used as a gate insulating film.

Further, niobium pentoxide (Nb ₂ O ₅₎ having a film thickness of about 50 nm is obtained by dissolving pentaethoxyniobium (Nb (OC ₂ H ₅ ) ₅ : liquid at room temperature) in ethanol, which is a low-boiling organic compound, to obtain a liquid raw material. ) A thin film can be formed. This thin film is used as a capacitor thin film for DRAM which is a high dielectric constant thin film.

Further, in the second embodiment, Pb (C ₁₁ H ₁₉ O ₂ ) ₂ , Zr (C ₁₁ H ₁₉ O ₂ ) ₄ and Ti (C ₁₁ H ₁₉ O ₂ ) ₂ (i-OC ₃ H ₇ ) ₂ A PZT (Pb (ZrTi) O ₃ ) film can also be formed using a mixed solution obtained by mixing acetone and acetone, which is a low-boiling organic compound. When the molar ratio is Pb: (Zr _x Ti _1-x ) = 1: 1 and X is changed, the relative dielectric constant of PZT can be freely changed.

In addition, in the first to third embodiments, water (H ₂ O) is used as an oxidizing agent, and in the fourth embodiment, oxygen (O ₂ ) gas is used. ₃ ) Hydrogen peroxide (H ₂ O ₂ ), metal alkoxide (Metal-Alkoxide) or the like may be used.

Further, without using the oxidant injection valve 51, a liquid oxidant (for example, water (H ₂ O) or hydrogen peroxide solution (H ₂ O ₂ )) can be used as the oxidant. In this case, as shown in FIG. 12, the oxidant supply mechanism 5 vaporizes the liquid oxidant by the bubbling method, and the oxidant container 5a and the oxidant in the oxidant container 5a contain argon gas. Gas supply pipe 5b for supplying and bubbling, an oxidant supply pipe 5c for supplying the oxidant vaporized by bubbling to the film forming chamber 2, and an oxidant introduction valve 5d provided on the supply pipe 5c. And an oxidant bypass valve 5e and a mass flow controller (MFC) 5f for controlling the flow rate of the argon gas. The film forming method of the film forming apparatus 1 configured as described above is the same as that when gas is used as the oxidizing agent.

The film forming apparatus does not form a metal oxide film, but nitrides such as ammonia (NH ₃ ), hydrazine (NH ₂ —NH ₂ ), and phenyl hydrazine (C ₆ H ₅ —NH—NH ₂ ). A metal nitride film may be formed using an agent.

In addition, in the third embodiment, in order to form the HfAlO _x film as the composite metal oxide film, trimethylaluminum (Al (CH ₃ ) ₃ ) as the first raw material and tetrakismethylethylaminohafnium as the second liquid raw material (Hf [N (CH ₃ ) (C ₂ H ₅ )] ₄ , TEMAHf) is used, but the raw material for forming the HfAlO _x film is not limited to the above, and is shown in FIG. Also good. Further, as shown in FIG. 13, another composite metal oxide thin film may be formed, and examples of raw materials for forming these films include those listed in FIG. 13. In addition, in the raw material shown in FIG. 13, especially about room temperature (about 25 degreeC), it is applied to the direct spraying of this invention by raising vapor pressure using a low boiling point organic compound about a solid or a liquid. It is possible.

In the fourth embodiment, TEMAHf is used as the amine-based organometallic compound and n-pentane is used as the low-boiling organic compound. However, the following amine-based organometallic compounds and low-boiling organic compounds are used. be able to. That is, as an amine-based organometallic compound, tetrakisdimethylaminohafnium (Hf [N (CH ₃ ) ₂ ] ₄ , TDMAHf), tetrakisdiethylaminohafnium (Hf [N (C ₂ H ₅ ) ₂ ] ₄ , TDEAHf), tetrakisdimethyl Aminozirconium (Zr [N (CH ₃ ) ₂ ] ₄ , TDMAZr), tetrakisdiethylaminozirconium (Zr [N (C ₂ H ₅ ) ₂ ] ₄ , TDAZr) or tetrakismethylethylaminozirconium (Zr [N (CH ₃ ))
(C ₂ H ₅ )] ₄ , TEMAZr) or the like can also be used.

Further, as the low-boiling organic compound, a compound represented by C _X H _{2X + 2} , specifically, for example, i-pentane, n-hexane, i-hexane, benzene, or the like can be used. The combination of such an amine-based organometallic compound and a low-boiling organic compound is determined by selecting those capable of mutual dissolution. To determine whether mutual dissolution is possible, the critical solution temperature of these mixed solutions is obtained. If the critical solution temperature is room temperature (about 25 ° C.) or less, it is determined that mutual dissolution is possible, otherwise Mutual dissolution is not allowed. In addition, the low boiling point organic compound dissolved in TEMAHf is preferably one in which no oxygen atom is contained in the molecule. Benzene is effective only when increasing the saturated vapor pressure of TDEAHf.

  As a specific example, a vapor pressure curve of a mixed solution of TEMAHf and each of the above low boiling point organic compounds is shown in FIG. It can be seen from FIG. 14 that the saturated vapor pressure is increased in any mixed solution.

In the embodiment, argon (Ar) gas is used as the gas in the pressurization line for pumping the mixed solution or the like. However, any inert gas may be used, for example, nitrogen (N ₂ ) gas or helium ( He) gas can also be used. From the viewpoint of Henry's constant, helium (He) gas is preferably used.

  In addition, some or all of the above-described embodiments and modified embodiments may be combined as appropriate, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. .

1 is an overall configuration diagram of a film forming apparatus according to a first embodiment of the present invention. The schematic cross section of the injection valve in the embodiment. The figure which shows the film-forming method in the embodiment. The schematic diagram which shows the ALD process in the embodiment. The schematic diagram which shows the ALD process in 2nd Embodiment. The whole block diagram of the film-forming apparatus concerning 3rd Embodiment. The figure which shows the film-forming method in the embodiment. The schematic diagram which shows the ALD process in the embodiment. The whole block diagram of the film-forming apparatus which concerns on 4th Embodiment. The vapor pressure curve of the mixed solution of TEMAHf and n-pentane. The figure which shows the film-forming method in the embodiment. The whole block diagram of the film-forming apparatus which concerns on other deformation | transformation embodiment. The figure which shows the combination of the raw material used for a composite metal oxide film and its film-forming. The vapor pressure curve of the mixed solution of TEMAHf and each low boiling point organic compound.

Explanation of symbols

W ... Substrate 1 ... Deposition device 2 ... Deposition chamber 3 ... Temperature control mechanism (substrate heater)
4 ... Liquid raw material supply mechanism (first supply mechanism)
41 ... Liquid raw material injection valve (first injection valve)
5 ... Oxidant supply mechanism (second supply mechanism)
51 ... Oxidant injection valve (second injection valve)
6 ... Purge gas supply mechanism 7 ... Pressure adjusting mechanism 8 ... Control device

Claims (7)

  A film forming method using an atomic layer growth method, characterized in that a liquid material made of an organometallic compound is directly injected by an injection valve into a film forming chamber that holds a substrate inside.   2. The film forming method using an atomic layer growth method according to claim 1, wherein a liquid oxidizing agent or nitriding agent is directly injected into the film forming chamber by an injection valve.   3. The film forming method using an atomic layer growth method according to claim 1, wherein the liquid raw material is a mixed solution composed of two or more kinds of organometallic compounds.   3. The film forming method using an atomic layer growth method according to claim 1, wherein the liquid material is a mixed solution in which a low-boiling organic compound is mixed with a solid or liquid organometallic compound at room temperature.   5. The film forming method using an atomic layer growth method according to claim 4, wherein the organometallic compound is an amine-based organometallic compound. 6. The film forming method using an atomic layer growth method according to claim 4, wherein the low boiling point organic compound is a compound represented by C _X H _{2X + 2} or benzene. A film formation chamber for holding the substrate inside;
A first supply mechanism for directly injecting a liquid source composed of an organometallic compound into the film forming chamber;
A second supply mechanism for supplying an oxidizing agent or a nitriding agent into the film forming chamber;
A purge gas supply mechanism for supplying a purge gas for purging the film forming chamber;
And a control device that controls the first supply mechanism, the second supply mechanism, and the purge gas supply mechanism so that a film is formed by atomic layer growth on the substrate.