JP2015119045A - Method for forming silicon nitride-containing thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a silicon nitride-containing thin film, capable of performing deposition at a temperature of 400°C or below without using a precursor having halogen.SOLUTION: In a method for forming a silicon nitride-containing thin film of a silicon oxynitride film (SiON film) or a silicon nitride film (SiN film) on a substrate by means of a chemical vapor deposition method (CVD method) or an atomic layer deposition method (ALD method), deposition is performed using a silicon-containing compound [H-Si-(NCO)] (n=2 to 4) and a nitrogen-containing compound serving as a nitriding source.

Description

  The present invention relates to a method for forming a silicon nitride-containing thin film.

In the field of silicon semiconductors, MEMS (Micro Electro Mechanical Systems) and optical elements, silicon oxide films (SiO ₂ ), silicon oxynitride films (SiON) or silicon nitride films (SiN) are used for various applications. A typical application of the silicon oxide film is an interlayer insulating film. A typical application of a silicon oxynitride film or a silicon nitride film is a barrier film used to protect a device from moisture or the like.

By the way, in Patent Documents 1 to 3, “CH _3n —Si— (NCO) _{4 -n} (n = 0 to 3)”, “H—Si— (NCO) are used as precursors when forming a silicon oxide film. ₃ ) and other silicon compounds having an isocyanate group have been reported.

Specifically, Patent Document 1 discloses “Si— (NCO) ₄ ”, “CH ₃ —Si— (NCO) ₃ ” and “(CH ₃ ) ₂ —Si— () as silicon compounds having an isocyanate group. A method of producing a low dielectric constant porous silica film (SiO ₂ ) by chemical vapor deposition (CVD) using “NCO) ₃ ” is disclosed.

Patent Document 2 discloses a method for producing a low dielectric constant silicon oxide insulating film by plasma CVD using “Si— (NCO) ₄ ” and a chalcogen fluoride compound. Further, Patent Document 3 discloses a method for forming a silicon oxide film by a CVD method and an atomic layer deposition method (ALD method) using triisocyanatosilane “H—Si— (NCO) ₃ ” as a precursor. Yes.

  As described above, the silicon compound having an isocyanate group is known as a precursor when forming a silicon oxide film, but is known to be used as a precursor when forming a silicon oxynitride film or a silicon nitride film. It was not done.

  On the other hand, typical precursors for forming a silicon oxynitride film (SiON) or a silicon nitride film (SiN) used as a barrier film include, for example, Vistaly butylaminosilane (BTBAS) and dichlorosilane (DCS). Silicon compounds are known.

  Here, as a conventional film forming method using a typical precursor, for example, a silicon nitride film (SiN) is formed at a film forming temperature of 600 ° C. by chemical vapor deposition (CVD) using DCS and ammonia. How to do is known. Similarly, a method of forming a silicon nitride film (SiN) at a film forming temperature of 400 ° C. by atomic deposition (ALD) using BTBAS and ammonia plasma is also known.

  In Patent Document 4 and Patent Document 5, as a conventional silicon oxynitride film (SiON) film forming method, DCS, oxygen plasma, and ammonia plasma are used, and a method of forming the film at a film forming temperature of 400 ° C. by ALD method. It is disclosed.

Japanese Patent No. 3633821 Japanese Patent Laid-Open No. 10-004089 JP 2011-080108 A JP 2007-0119145 A Japanese Patent No. 5190307

  Incidentally, in recent years, miniaturization and high integration have progressed in the semiconductor manufacturing process, and development of a low-temperature thin film forming technique is desired. Along with the progress of such miniaturization and high integration, in the film formation process of the barrier film used to protect the device from moisture and the like with the improvement of the base substrate, the temperature is 400 ° C. or less, more preferably about 200 ° C. In reality, the development of a precursor capable of forming a thin film is desired.

  A precursor for forming a silicon oxynitride film (SiON) or silicon nitride film (SiN) that is currently used as a general barrier film is required to be halogen-free and to be formed at a low temperature of 400 ° C. or lower. It has been.

  However, in film formation using BTBAS as a precursor, there is a problem that it is difficult to form a thin film at a temperature lower than a film formation temperature of 400 ° C. In addition, in the film formation using a precursor having a halogen such as DCS disclosed in Patent Document 4 and Patent Document 5, if a metal such as tungsten exists in the base, there is a possibility of causing corrosion. There was a problem.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for forming a silicon nitride-containing thin film that can be formed at a temperature of 400 ° C. or lower without using a precursor having halogen. To do.

  As a result of diligent studies to solve such problems, the inventors of the present application have found that silicon compounds having an isocyanate group, which has been conventionally known as a precursor for forming a silicon oxide film, are formed from a silicon oxynitride film (SiON). ) Or a precursor that can be formed at 400 ° C. or lower when forming a silicon nitride film (SiN), and the present invention has been completed by examining the film forming conditions in detail.

That is, the present invention has the following configuration.
The invention according to claim 1 includes silicon nitride containing a silicon oxynitride film (SiON film) or a silicon nitride film (SiN film) on a substrate by chemical vapor deposition (CVD) or atomic deposition (ALD). A method of forming a thin film comprising:
A method for forming a silicon nitride-containing thin film, comprising forming a film using a silicon-containing compound represented by the following chemical formula (1) and a nitrogen-containing compound serving as a nitriding source.
H _(4-n) -Si- (NCO) _n (1)
In addition, in said chemical formula (1), n is an integer of 2-4.

  The invention according to claim 2 is the method for forming a silicon nitride-containing thin film according to claim 1, wherein the silicon-containing compound is supplied as a gas at 20 to 70 ° C.

  The invention according to claim 3 is characterized in that the nitrogen-containing compound contains at least one of ammonia, hydrazine, monomethylhydrazine, dimethylhydrazine, diphenylhydrazine, dimethylamine, methylamine, tertiary butylamine, and butylamine. The method for forming a silicon nitride-containing thin film according to claim 1 or 2.

  The invention according to claim 4 is the method for forming a silicon nitride-containing thin film according to any one of claims 1 to 3, wherein the activated nitrogen-containing compound is supplied.

  The invention according to claim 5 is the method for forming a silicon nitride-containing thin film according to any one of claims 1 to 4, wherein the film is formed in the presence of hydrogen gas.

  The invention according to claim 6 is characterized in that a silicon oxynitride film (SiON film) or a silicon nitride film (SiN film) is selectively formed by adjusting the supply amount of the nitrogen-containing compound. Item 6. The method for forming a silicon nitride-containing thin film according to any one of Items 1 to 5.

  According to the seventh aspect of the present invention, when the silicon oxynitride film (SiON film) is formed, the supply amount of the nitrogen-containing compound is made smaller than the required supply amount, and the silicon nitride film (SiN film) is formed. 7. The method for forming a silicon nitride-containing thin film according to claim 6, wherein when the film is formed, the supply amount of the nitrogen-containing compound is made larger than a required supply amount.

  The invention according to claim 8 is the method for forming a silicon nitride-containing thin film according to any one of claims 1 to 7, wherein the film is formed in a range of 100 ° C. to 400 ° C.

  The method for forming a silicon nitride-containing thin film of the present invention can form a silicon nitride-containing thin film at a temperature of 400 ° C. or lower without using a precursor having halogen.

It is a systematic diagram which shows the film-forming apparatus used for the formation method of the silicon nitride containing thin film which is one Embodiment to which this invention is applied. It is a figure which shows the FTIR spectrum of the silicon oxynitride film in Example 3. It is a figure which shows the FTIR spectrum of the silicon nitride film in Example 4.

  Hereinafter, a method for forming a silicon nitride-containing thin film, which is an embodiment to which the present invention is applied, will be described in detail with reference to the drawings together with the configuration of a film forming apparatus applicable thereto. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

  A method for forming a silicon nitride-containing thin film according to an embodiment to which the present invention is applied includes a silicon oxynitride film (SiON film) or a substrate formed on a substrate by chemical vapor deposition (CVD) or atomic deposition (ALD). This is a method of forming a silicon nitride-containing thin film of a silicon nitride film (SiN film).

<Deposition system>
First, an example of the configuration of a film forming apparatus used in the method for forming a silicon nitride-containing thin film according to this embodiment will be described.
FIG. 1 is a system diagram schematically showing a film forming apparatus that can be used in a method for forming a silicon nitride-containing thin film according to an embodiment to which the present invention is applied. As shown in FIG. 1, a film forming apparatus 1 that can be used in the method for forming a silicon nitride-containing thin film according to the present embodiment accommodates a substrate 2 to be processed, a vacuum chamber (reaction unit) 3, a vacuum A heater (heating means) 4 provided for heating the substrate 2 in the chamber 3 and a plasma generator (remote plasma generator) 5 provided in the front stage (primary side) of the vacuum chamber 3 are schematically configured. ing.

  More specifically, as shown in FIG. 1, a first supply path L1 is connected to the front stage (primary side) of the vacuum chamber 3, and a plasma generator 5 is provided in the first supply path L1. ing. The second supply path L2 and the third supply path L3 are connected to the first supply path L1. Further, the second supply path L2 is connected to a source gas supply path L4 that branches from the second supply path L2 and passes through the source container 6 and then rejoins the second supply path L2. Furthermore, a nitriding source supply path L5 for supplying a nitrogen-containing compound serving as a nitriding source is connected to the third supply path L3. Note that a mass flow controller (MFC) 10 is provided in each of the supply paths L1, L2, L3, and L5.

  On the other hand, an exhaust path L6 is connected to the rear stage (secondary side) of the vacuum chamber 3. A dry pump 7 for exhausting the gas in the vacuum chamber 3 is connected to the exhaust path L6. Further, a pressure controller 8 and a pressure gauge 9 for controlling the pressure in the vacuum chamber 3 are provided in the exhaust path L6.

  The film forming apparatus 1 shows a case where a plasma ALD apparatus is used as an example. In addition, specifically, any one of a plasma CVD apparatus, a thermal CVD apparatus, a plasma ALD apparatus, and a thermal ALD apparatus can be used in the method for forming a silicon nitride-containing thin film of this embodiment.

  An inert gas supply source (not shown) is connected to the first supply path L1 so that a purge gas can be supplied to the vacuum chamber 3. The inert gas that can be used as the purge gas is not particularly limited, and for example, helium (He), argon (Ar), and the like are preferable.

  An inert gas supply source (not shown) is connected to the second and third supply paths L2 and L3, respectively, and can supply a carrier gas (base gas) that carries a nitrogen-containing compound serving as a source gas or a nitriding source. It is said that. The inert gas that can be used as the carrier gas is not particularly limited, and for example, helium (He), argon (Ar), and the like are preferable.

  The source gas supply path L <b> 4 is provided for supplying a source material in a gas phase to the vacuum chamber 3 by entraining the source gas with the carrier gas when passing through the source container 6. More specifically, the inside of the raw material container 6 can be bubbled with a carrier gas, and the vapor of the raw material can be supplied into the vacuum chamber 3 together with the carrier gas from the gas phase in the raw material container 6. Further, the raw material container 6 is provided with a heating means (not shown) so that the liquid raw material in the raw material container 6 can be heated.

In the film forming apparatus 1, the second supply path L2, the source gas supply path L4, and the source container 6 constitute a source gas supply unit. The third supply path L3 and the nitridation source supply path L5 schematically constitute a nitridation source supply means.

  The plasma generator (remote plasma generator) 5 is provided in the first supply path L1 as a plasma source. In addition, a nitriding source supply path L5 for supplying a nitrogen-containing compound serving as a nitriding source is connected to the first supply path L1 through the third supply path L3. Supply route. Thus, by arranging the plasma generator 5 in the supply path of the nitrogen source, the nitrogen-containing compound activated by this plasma source can be supplied to the surface of the substrate 2 placed in the vacuum chamber 3. ing.

<Method for forming silicon nitride-containing thin film>
The method for forming a silicon nitride-containing thin film according to this embodiment uses a silicon oxynitride film (SiON film) or silicon on a substrate using a silicon-containing compound represented by the following chemical formula (1) and a nitrogen-containing compound serving as a nitriding source. A silicon nitride-containing thin film of a nitride film (SiN film) is formed.
H _(4-n) -Si- (NCO) _n (1)

In addition, in said chemical formula (1), n is an integer of 2-4. That is, as a silicon-containing compound, diisocyanate silane [H ₂ —Si— (NCO) ₂ ], triisocyanate silane [H—Si— (NCO) ₃ ], tetraisocyanate silane [Si— (NCO) _4]. ].

  Although it does not specifically limit as a nitrogen-containing compound used as a nitriding source, For example, ammonia, hydrazine, monomethylhydrazine, dimethylhydrazine, diphenylhydrazine, dimethylamine, methylamine, tertiary butylamine, butylamine etc. are mentioned. Any one of these may be used alone, or one containing one or more may be used.

Next, the method for forming the silicon nitride-containing thin film of the present embodiment will be specifically described by taking as an example the case where the film forming apparatus (plasma ALD apparatus) 1 shown in FIG. 1 is used.
First, the substrate 2 placed in the vacuum chamber 3 is heated by the heater 4. The substrate temperature (that is, the film formation temperature) is preferably in the range of 100 to 400 ° C., more preferably 200 ° C. or less. Next, after the inside of the vacuum chamber 3 is purged from the first supply path 1 using the purge gas, the gas in the vacuum chamber 3 is exhausted to the exhaust path 6 by the dry pump 7.

(First step)
Next, the silicon-containing compound represented by the chemical formula (1) is supplied into the vacuum chamber 3 (reaction part) and adsorbed on the surface of the substrate 2 for a required time (for example, 10 seconds) (first step). Specifically, the carrier gas is supplied from the second supply path L2 to the source gas supply path L4, the heated source container 6 is bubbled by the carrier gas, and the vapor of the silicon-containing compound is vaporized from the gas phase of the source container 6 (Source gas) is supplied into the vacuum chamber 3 together with the carrier gas.

  Here, it is preferable from a viewpoint of the stable supply of a raw material to supply a silicon containing compound to a reaction part as 20-70 degreeC gas (gas). Here, it is not preferable that the gas temperature of the silicon-containing compound is less than 20 ° C. because the vapor pressure becomes low and the raw material cannot be stably supplied. On the other hand, when the temperature exceeds 70 ° C., the inside of the piping is blocked by deposits, and it becomes impossible to supply the silicon-containing compound. Note that the method for supplying the silicon-containing compound gas is not limited to the bubbling method shown in FIG.

(Second step)
Next, a purge gas is supplied from the first supply path 1 into the vacuum chamber 3 for a required time (for example, 10 seconds) to purge the vacuum chamber 3 (second step). Thereby, the unreacted silicon-containing compound is removed from the vacuum chamber 3.

(Third step)
Next, a nitriding source is supplied into the vacuum chamber 3 (reaction part) for a required time (for example, 10 seconds) (third step). In addition, when supplying a nitriding source, it is preferable to heat the piping which comprises the 3rd supply path | route L3 and the nitriding source supply path | route L5 to required temperature (for example, 100 degreeC).

  Here, when supplying the nitriding source, it is preferable to supply the activated nitrogen-containing compound to the reaction part. Thereby, compared with the case where the nitrogen-containing compound which is not activated is supplied, the reactivity with the raw material (first step) adsorbed on the surface of the substrate 2 is improved, and as a result, low-temperature film formation is possible. The activated nitrogen-containing compound means a state that is not a molecule, that is, an atom, radical, ion, or the like.

  In order to supply the activated nitrogen-containing compound, a plasma generator (remote plasma generator) 5 provided in the first supply path L1 is used as a plasma source, and a required condition (for example, plasma output: 2 MHz) is used. 375 W or the like). The method for activating the nitrogen-containing compound is not particularly limited, and for example, a method using a hot wire or a method using a catalyst may be used.

(4th step)
Next, a purge gas is supplied from the first supply path 1 into the vacuum chamber 3 for a required time (for example, 10 seconds) to purge the vacuum chamber 3 (fourth step). Thereby, the unreacted nitriding source is removed from the vacuum chamber 3.

  The above first step to fourth step are repeated a plurality of times (for example, 600 cycles) as one cycle. Thereby, a thin film with a desired film thickness can be formed on the substrate 2.

  By the way, the present inventors have newly found that the amount of nitrogen and the amount of oxygen contained in the silicon nitride-containing film change by controlling the supply time of the nitriding source. That is, it has been found that a silicon oxynitride film (SiON film) and a silicon nitride film (SiN film) can be selectively produced by changing the supply time of the nitriding source.

  Specifically, by adjusting the supply amount of the nitrogen-containing compound in the third step described above, the silicon oxynitride film (SiON film) and the silicon nitride film (SiN film) without changing the precursor (silicon-containing compound) ) Can be selectively formed. For example, the silicon oxynitride film (SiON film) is formed by making the supply amount of the nitrogen-containing compound smaller than the required supply amount serving as a threshold (that is, shortening the supply time) in the third step. be able to. On the other hand, the silicon nitride film (SiN film) is formed by increasing the supply amount of the nitrogen-containing compound in the third step above the required supply amount serving as a threshold (that is, increasing the supply time). Can do.

  In addition, the inventors of the present application newly found that the refractive index of a thin film obtained is increased by forming a silicon nitride-containing film in the presence of hydrogen gas as compared with the absence of hydrogen gas. It was. That is, it has been found that by forming a silicon nitride-containing film in the presence of hydrogen gas, a film that is dense and hardly changes over time can be obtained.

  Specifically, in the method for forming a silicon nitride-containing thin film of this embodiment, the film quality of the thin film formed on the substrate 2 can be improved by forming the film in the presence of hydrogen gas. More specifically, hydrogen gas is used as a gas supplied from the third supply path L3, and a nitriding source is supplied to the reaction unit in a hydrogen atmosphere in the third step.

<Silicon nitride-containing thin film>
The thin film obtained by the method for forming a silicon nitride-containing thin film according to the present embodiment is, for example, an infrared absorption spectrum measurement (for example, Perkin Elmer Fourier infrared spectrophotometer device) or a refractive index measurement (for example, The film quality can be confirmed and evaluated by a spectroscopic ellipsometer manufactured by SOPRA. Specifically, in the refractive index measurement using a spectroscopic ellipsometer, the refractive index is 1.4 to 1.6 in the case of a silicon oxynitride film (SiON film) in the range of 150 to 450 ° C. On the other hand, in the case of a silicon nitride film (SiN film), the refractive index is 1.6 to 2.0.

  As described above, according to the method for forming a silicon nitride-containing thin film of this embodiment, the silicon nitride-containing thin film can be formed at a temperature of 400 ° C. or less without using a precursor having halogen.

  In particular, when triisocyanate silane or tetraisocyanate silane is used as a precursor, a silicon nitride-containing thin film can be formed at a low temperature (150 to 300 ° C.).

  Further, according to the method for forming a silicon nitride-containing thin film of the present embodiment, the silicon oxynitride film (SiON film) can be adjusted without changing the precursor (silicon-containing compound) by adjusting the supply amount of the nitrogen-containing compound. A silicon nitride film (SiN film) can be selectively formed.

  Furthermore, according to the method for forming a silicon nitride-containing thin film of this embodiment, the film quality of the obtained thin film can be improved by forming the film in the presence of hydrogen gas.

Specific examples are shown below.
<Example 1>
A method for supplying a precursor (silicon-containing compound) was examined using the film forming apparatus 1 shown in FIG.
First, after the raw material container 6 of triisocyanatosilane [H—Si— (NCO) ₃ ] is heated in the range shown in Table 1 below, the inside of the raw material container 6 is bubbled with a carrier gas, The source gas was supplied from the phase to the reaction part (vacuum chamber 3). The results are shown in Table 1.

  As shown in Table 1, the raw material gas could be stably supplied when the heating temperature of the raw material container 6 was in the range of 20 to 70 ° C. However, it has been found that when the heating temperature of the raw material container 6 exceeds 70 ° C., for example, at 80 ° C., the piping constituting the raw material gas supply path L4 is blocked by deposits.

<Comparative Example 1>
After transporting triisocyanatosilane as a precursor to a vaporization chamber heated to 80 ° C. (VC-1410, manufactured by HORIBA STEC) in a liquid state, the liquid is vaporized in the vaporization chamber and a reaction part (vacuum as a raw material gas) Supply to chamber 3) was performed. As a result, it was found that the vaporizer was blocked and it was difficult to supply a stable raw material gas.

<Comparison verification 1>
From the results of the above Example 1 and Comparative Example 1, it was confirmed that when the triisocyanate silane is used as the precursor, the supply method of Example 1 is preferable as the supply method of the gaseous source gas.

<Example 2>
Using the film forming apparatus 1 shown in FIG. 1, a film forming experiment was performed by the plasma ALD method. The details of the experimental conditions were as follows.
(Precursor)
Conducted for each of the silicon-containing compounds represented by the above chemical formula (1): H _4−n —Si— (NCO) _n , n = 1 to 4 (experimental conditions)
Reaction temperature (substrate temperature): 150, 200, 250, 4-level nitriding source (reactive gas) at 300 ° C .: Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas supply to a reaction part is carried out to a silicon-containing compound for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds.
(4) Purge with helium for 10 seconds to remove unreacted nitriding source.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

<Comparative Example 2>
Similarly to Example 2 described above, a film formation experiment was performed by the plasma ALD method using the film formation apparatus 1 shown in FIG. The details of the experimental conditions were as follows.
(Precursor)
Bicter Shaly Butylaminosilane (BTBAS)
(Experimental conditions)
Reaction temperature (substrate temperature): 350, 400, 450 ° C. Three-level nitriding source (reactive gas): ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) BTBAS is supplied to the reaction section and adsorbed for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds.
(4) Purge with helium for 10 seconds to remove unreacted nitriding source.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

<Comparative Example 3>
Similarly to Example 2 described above, a film formation experiment was performed by the plasma ALD method using the film formation apparatus 1 shown in FIG. The details of the experimental conditions were as follows.
(Precursor)
Dichlorosilane (DCS)
(Experimental conditions)
Reaction temperature (substrate temperature): 150, 200, 250, 300, 350, 400, 450 ° C. Seven-level nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) DCS is supplied to the reaction section with gas and adsorbed for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds.
(4) Purge with helium for 10 seconds to remove unreacted nitriding source.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

<Comparison verification 2>
The adsorption evaluation of the thin film obtained in Example 2 and Comparative Examples 2 and 3 was performed. Here, the adsorption evaluation was performed by calculating a film formation amount (GPC) per cycle after measuring the film thickness with a spectroscopic ellipsometer (manufactured by SOPRA).
In general, when a film is formed by the ALD method, the GPC value is very important information for evaluating the adsorption to the substrate. Specifically, for example, when the adhesion probability of the source gas is low, the GPC value becomes small. For this reason, when the GPC value is small and close to zero, it can be determined that the adsorption of the raw material gas hardly occurs as a result.
Table 1 shows the evaluation results of the film formation amount GPC per cycle at each film formation temperature in Example 2 and Comparative Examples 2 and 3.

  As shown in Table 1, regarding Comparative Example 2 in which BTBAS was used as a precursor, a thin film was not obtained when the film formation temperature reached 350 ° C. That is, when BTBAS was used as the precursor, it was confirmed that film formation at a temperature lower than 400 ° C. was impossible. In Comparative Example 3 using DCS as the precursor, it was confirmed that film formation at a temperature lower than 400 ° C. was possible. However, since halogen is contained in DCS as a precursor in the first place, there is a problem that it causes corrosion of metal.

  On the other hand, with respect to Example 2 using a silicon-containing compound as a precursor, almost no thin film was obtained with isocyanate silane (n = 1). With diisocyanate silane (n = 2), a thin film was obtained at a film forming temperature of 300 ° C. Furthermore, with triisocyanatosilane (n = 3), a thin film was obtained at a film forming temperature of 150 to 300 ° C. Furthermore, with tetraisocyanatosilane (n = 4), it was confirmed that a thin film could be obtained at 250 ° C. and 300 ° C., although a thin film could not be obtained at low film formation temperatures of 150 ° C. and 200 ° C.

  From the above results, although BTBAS currently used as a halogen-free precursor cannot be formed at a film forming temperature lower than 350 ° C., the triisocyanate silane, tetraisocyanate of the present invention can be used as a precursor. In the case of using natosilane, it was confirmed that ideal atomic layer deposition occurs at a low temperature (150 to 300 ° C.).

<Example 3>
Using the film forming apparatus 1 shown in FIG. 1, a silicon oxynitride film (SiON film) was formed by plasma ALD, and the film quality was evaluated. The details of the experimental conditions were as follows.
(Precursor)
Triisocyanatosilane [H—Si— (NCO) ₃ ]
(Experimental conditions)
Reaction temperature (substrate temperature): 150 to 450 ° C. (7 levels)
Nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas is supplied to the reaction part of triisocyanatosilane for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 5 seconds.
(4) Purging with helium for 5 seconds to remove unreacted nitriding source.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

(Film quality evaluation)
Adsorption evaluation and film quality evaluation of the obtained thin film were performed. Here, the adsorption evaluation was performed by calculating GPC after measuring the film thickness with a spectroscopic ellipsometer (manufactured by SOPRA). The film quality was evaluated based on the refractive index of the thin film measured by a spectroscopic ellipsometer (manufactured by SOPRA, GES5E). Table 3 shows the results.

As shown in Table 3, when triisocyanatosilane was used as the precursor, it was confirmed that film formation was possible at a film formation temperature of 150 to 450 ° C.
In addition, as a result of measuring the refractive index of the thin film using a spectroscopic ellipsometer, a refractive index of 1.4 to 1.6 is obtained when the film forming temperature is in the range of 150 to 450 ° C., both of which are silicon oxynitride films (SiON films) It was confirmed that.

(Infrared absorption spectrum analysis results)
FT-IR (Perkin Elmer, Spectrum 400) spectrum measurement of the thin film (substrate temperature: 450 ° C.) obtained in Example 3 was performed. The results are shown in FIG.
As shown in FIG. 2, Si—O vibration and Si—N vibration were observed. From this result, it was confirmed that when a film was formed under the conditions of Example 3, a SiON film was obtained.

  As described above, in Example 3, when the film was formed with the supply time of the nitriding source being 5 seconds, the oxygen component of the isocyanate group (NCO group) of triisocyanatosilane as a raw material was taken into the film, and SiON It was confirmed that a film could be produced.

<Example 4>
Using the film forming apparatus 1 shown in FIG. 1, a silicon nitride film (SiN film) was formed by plasma ALD, and the film quality was evaluated. The details of the experimental conditions were as follows.
(Precursor)
Triisocyanatosilane [H—Si— (NCO) ₃ ]
(Experimental conditions)
Reaction temperature (substrate temperature): 150 to 400 ° C. (6 levels)
Nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas is supplied to the reaction part of triisocyanatosilane for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds.
(4) Purge with helium for 10 seconds to remove unreacted nitriding source.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

(Film quality evaluation)
Adsorption evaluation and film quality evaluation of the obtained thin film were performed. Here, the adsorption evaluation and the film quality evaluation were performed in the same manner as in Example 3 described above. Table 4 shows the results.

As shown in Table 4, when triisocyanatosilane was used as the precursor, it was confirmed that film formation was possible at a film formation temperature in the range of 150 to 400 ° C.
In addition, as a result of measuring the refractive index of the thin film using a spectroscopic ellipsometer, a refractive index of 1.6 to 2.0 is obtained when the film forming temperature is in the range of 150 to 400 ° C., both of which are silicon nitride films (SiN films). I confirmed that there was.

(Infrared absorption spectrum analysis results)
FT-IR (Perkin Elmer, Spectrum 400) spectrum measurement of the thin film (substrate temperature: 300 ° C.) obtained in Example 4 was performed. The results are shown in FIG.
As shown in FIG. 3, Si-N vibration and Si-NH-Si vibration were observed. From this result, it was confirmed that when the film was formed under the conditions of Example 4, a SiN film was obtained.

  As described above, in Example 4, the supply time of the nitriding source was 10 seconds, which is twice that of Example 3, so that the oxygen component of the isocyanate group (NCO group) of the triisocyanate silane that is the raw material was reduced. It was removed and it was confirmed that a SiN film could be produced.

<Example 5>
Using the film forming apparatus 1 shown in FIG. 1, a film was formed by the plasma ALD method, and the film quality was evaluated. The details of the experimental conditions were as follows.
(Precursor)
Triisocyanatosilane [H—Si— (NCO) ₃ ]
(Experimental conditions)
Reaction temperature (substrate temperature): 100 ° C
Nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 375 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas is supplied to the reaction part of triisocyanatosilane for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds.
(4) Purge with helium for 10 seconds to remove unreacted nitriding source.
Number of cycles: 1000 cycles (the above series of steps is defined as one cycle)

(Film quality evaluation)
Adsorption evaluation and film quality evaluation of the obtained thin film were performed. Here, as a result of performing the adsorption evaluation and the film quality evaluation in the same manner as in Example 3 described above, the film formation amount (GPC) per cycle is 0.110 (Å / cycle), and the refractive index is 1.553. A membrane was obtained. From the above, it was confirmed that a silicon oxynitride film (SiON) was obtained when a film formation experiment was performed at a film formation temperature of 100 ° C. using triisocyanatosilane as a precursor.

<Example 6>
A silicon oxynitride film (SiON film) is formed using the film forming apparatus 1 shown in FIG. 1 in a state where hydrogen gas coexists by the plasma ALD method (that is, changing the helium line of L3 to a hydrogen line), The film quality was evaluated.
Specifically, in Step 1, an L1 helium line was used and a precursor was supplied in a helium atmosphere. In Step 2, unreacted raw materials were removed by the L1 helium line. Next, in Step 3, the L1 helium line was switched to the L3 hydrogen line, and a nitriding source was supplied into the vacuum chamber 3 in a hydrogen atmosphere. Next, in Step 4, the L3 hydrogen line was switched again to L1 helium, and the unreacted nitriding source and hydrogen were removed. Under such a series of cycles, a hydrogen atmosphere was selectively created.
The details of the experimental conditions were as follows.
(Precursor)
Triisocyanatosilane [H—Si— (NCO) ₃ ]
(Experimental conditions)
Reaction temperature (substrate temperature): 350 ° C
Nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 1125 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas is supplied to the reaction part of triisocyanatosilane for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 5 seconds in a hydrogen atmosphere.
(4) Purging with helium for 10 seconds to remove unreacted nitriding source and hydrogen.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

(Film quality evaluation)
Adsorption evaluation and film quality evaluation of the obtained thin film were performed. As a result of performing the adsorption evaluation and the film quality evaluation in the same manner as in Example 3 described above, the film formation amount (GPC) per cycle is 0.172 (Å / cycle) and the refractive index is 1.590. was gotten.
Here, compared with the case where hydrogen gas was not added (Example 3, reaction temperature: 350 ° C.), the refractive index increased in the presence of hydrogen gas, and a film that was dense and hardly changed over time was obtained. It was confirmed. The reason is considered to be that the ammonia active species generated by the plasma and a large amount of hydrogen active species have some positive effect on the film formation.

<Example 7>
Using the film forming apparatus 1 shown in FIG. 1, a silicon nitride film (SiN film) was formed by the plasma ALD method in the presence of hydrogen gas in the same manner as in Example 6, and the film quality was evaluated. The details of the experimental conditions were as follows.
(Precursor)
Triisocyanatosilane [H—Si— (NCO) ₃ ]
(Experimental conditions)
Reaction temperature (substrate temperature): 350 ° C
Nitriding source (reactive gas): Ammonia pressure: 53 Pa
Piping temperature of nitriding source supply path: 100 ° C
Plasma output: 2 MHz, 1125 W (inductively coupled plasma, manufactured by LANDMARK TECHNOLOGY, LG3000)
Process:
(1) Gas is supplied to the reaction part of triisocyanatosilane for 10 seconds.
(2) Purging with helium for 10 seconds to remove unreacted raw materials.
(3) A nitriding source is supplied to the reaction section for 10 seconds in a hydrogen atmosphere.
(4) Purging with helium for 10 seconds to remove unreacted nitriding source and hydrogen.
Number of cycles: 300 cycles (the above series of steps is defined as one cycle)

(Film quality evaluation)
Adsorption evaluation and film quality evaluation of the obtained thin film were performed. As a result of performing the adsorption evaluation and the film quality evaluation in the same manner as in Example 3 described above, the film formation amount (GPC) per cycle is 0.184 (Å / cycle), and the refractive index is 1.790. was gotten.
Here, compared with the case where hydrogen gas was not added (Example 4, reaction temperature: 350 ° C.), the refractive index increased in the presence of hydrogen gas, and a film that was dense and hardly changed over time was obtained. It was confirmed. The reason is considered to be that the ammonia active species generated by the plasma and a large amount of hydrogen active species have some positive effect on the film formation.

1 ... Film formation equipment (plasma ALD equipment)
2 ... Substrate 3 ... Vacuum chamber 4 ... Heater (heating means)
5 ... Plasma generator (remote plasma)
6 ... Raw material container 7 ... Dry pump 8 ... Pressure controller 9 ... Pressure gauge 10 ... Mass flow meter (MFC)
L1 ... 1st supply path L2 ... 2nd supply path L3 ... 3rd supply path L4 ... Raw material gas supply path L5 ... Nitride source supply path L6 ... Exhaust path

Claims (8)

A method for forming a silicon nitride-containing thin film of a silicon oxynitride film (SiON film) or a silicon nitride film (SiN film) on a substrate by chemical vapor deposition (CVD) or atomic deposition (ALD). ,
A method for forming a silicon nitride-containing thin film, comprising forming a film using a silicon-containing compound represented by the following chemical formula (1) and a nitrogen-containing compound serving as a nitriding source.
H _(4-n) -Si- (NCO) _n (1)
In addition, in said chemical formula (1), n is an integer of 2-4.   The method for forming a silicon nitride-containing thin film according to claim 1, wherein the silicon-containing compound is supplied as a gas at 20 to 70 ° C.   The nitrogen-containing compound contains at least one or more of ammonia, hydrazine, monomethylhydrazine, dimethylhydrazine, diphenylhydrazine, dimethylamine, methylamine, tertiary butylamine, and butylamine. A method for forming a silicon nitride-containing thin film as described.   The method for forming a silicon nitride-containing thin film according to any one of claims 1 to 3, wherein the activated nitrogen-containing compound is supplied.   The method for forming a silicon nitride-containing thin film according to any one of claims 1 to 4, wherein the film is formed in the presence of hydrogen gas.   6. The silicon oxynitride film (SiON film) or the silicon nitride film (SiN film) is selectively formed by adjusting the supply amount of the nitrogen-containing compound. The method for forming a silicon nitride-containing thin film according to the item. When forming the silicon oxynitride film (SiON film), the supply amount of the nitrogen-containing compound is less than the required supply amount,
The method for forming a silicon nitride-containing thin film according to claim 6, wherein when the silicon nitride film (SiN film) is formed, the supply amount of the nitrogen-containing compound is made larger than a required supply amount.   The method for forming a silicon nitride-containing thin film according to any one of claims 1 to 7, wherein the film is formed in a range of 100 ° C to 400 ° C.

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