JP2016164932A - Method and device for forming silicon nitride film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a silicon nitride film, capable of improving further film forming rate and also obtaining sufficient nitriding force even if a nitriding agent is thermally activated.SOLUTION: A method for forming a silicon nitride film includes the steps of: housing a treatment body in a processing chamber of a film forming device (Step 1); simultaneously supplying silicon material gas and nitride gas to the processing chamber (Step 2); maintaining the mixed atmosphere between the silicon material gas and the nitride gas in the processing chamber (Step 3); and exhausting the mixed atmosphere from the processing chamber (Step 4). Steps are repeated for the number of times set from Step 2 to Step 4, thereby the nitride gas contains a nitrogen-containing heterocyclic compound gas as a nitriding agent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silicon nitride film forming method and a film forming apparatus.

  One of the semiconductor device manufacturing processes is the need for low-temperature silicon nitride (SiN) film formation. Here, the low temperature refers to a region where the temperature in the film forming chamber is about 300 to 400 ° C. As a technique for forming a low-temperature SiN film, a combination of a silicon (Si) source gas having good adsorptivity and thermal decomposability in a low-temperature region and a nitriding agent capable of low-temperature nitriding is used.

  A chlorosilane-based gas is known as a Si source gas that provides a Si film that has good adsorptivity and thermal decomposability in a low-temperature region and that has good reactivity as a SiN material (see Patent Document 1).

Also, ammonia (NH ₃ ) gas is known as a nitriding agent capable of low-temperature nitriding (see also Patent Document 1). When using the NH ₃ gas as a nitriding agent, the NH _3, activated by heat or plasma. When NH ₃ is activated, the nitriding power necessary for nitriding the Si film is obtained in NH ₃ .

Furthermore, Patent Document 1 discloses that the film formation rate of the SiN film can be improved by simultaneously supplying dichlorosilane (DCS), which is a chlorosilane-based Si source gas, and NH ₃ , which is a nitriding agent, into the processing chamber. (See description in paragraph 0031).

JP 2006-49809 A

In Patent Document 1, the deposition rate of the SiN film can be improved by simultaneously supplying DCS and NH ₃ into the processing chamber. However, further improvement in the deposition rate of the SiN film is required.

In addition, when NH ₃ gas is used as a nitriding agent, it is difficult to obtain a sufficient nitriding power only by thermal activation. For this reason, in order to obtain higher nitriding power, radicalization of NH ₃ using plasma is used in combination. However, there is a concern that it is necessary to apply a high frequency power and damage the structure of the object to be processed.

  The present invention is a method for forming a silicon nitride film, which can further improve the film forming rate and can obtain sufficient nitriding power even if the nitriding agent is only thermally activated. And a film forming apparatus capable of performing the film forming method.

  A method for forming a silicon nitride film according to a first aspect of the present invention is a method for forming a silicon nitride film in which a silicon nitride film is formed on a surface to be processed of a target object. 1) a step of carrying the object to be processed into a processing chamber of a film forming apparatus; (2) a step of simultaneously supplying a silicon source gas and a nitriding gas into the processing chamber; and (3) the processing chamber. A step of holding in a mixed atmosphere of the silicon source gas and the nitriding gas; and (4) a step of evacuating the processing chamber. The steps (2) to (4) are set. The nitriding gas contains a nitrogen-containing heterocyclic compound gas as a nitriding agent.

  A film forming apparatus according to a second aspect of the present invention is a film forming apparatus for forming a silicon nitride film on a processing target surface of a target object, a processing chamber for storing the target target object, A processing gas supply mechanism for supplying a gas used for processing into the processing chamber, a heating device for heating the substrate to be processed accommodated in the processing chamber, and exhausting the processing chamber through an exhaust port and an exhaust valve And the controller for controlling the exhaust mechanism, and the controller implements the silicon nitride film forming method according to the first aspect. As described above, the processing gas supply mechanism, the heating device, and the exhaust mechanism are controlled.

  According to the present invention, it is possible to further improve the film formation rate, and to form a silicon nitride film capable of obtaining a sufficient nitriding power even when the nitriding agent is only thermally activated. A film forming method and a film forming apparatus capable of performing the film forming method can be provided.

1 is a flowchart showing an example of a sequence of a method for forming a silicon nitride film according to the first embodiment of the invention Time chart of the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. 6 is a flowchart showing an example of a sequence of a method for forming a silicon nitride film according to the second embodiment of the present invention. Time chart of the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. 6 is a flowchart showing an example of a sequence of a silicon nitride film forming method according to the third embodiment of the present invention; Time chart of the sequence shown in FIG. Sectional drawing which shows schematically the state of the to-be-processed object in the sequence shown in FIG. The figure which shows the film-forming rate per cycle of a silicon nitride film The figure which shows the film | membrane composition of the silicon nitride film formed into a film according to 2nd Embodiment Diagram showing etching rate for 0.5% dilute hydrofluoric acid Diagram showing triazole compounds Diagram showing oxatriazole compounds Diagram showing tetrazole compounds Diagram showing triazine compounds The figure which shows a tetrazine type compound (1,2,3,4-tetrazine type compound) Diagram showing tetrazine compounds (1,2,3,5-tetrazine compounds) Diagram showing benzotriazole compounds Diagram showing benzotriazine compounds Diagram showing benzotetrazine compounds 1 is a longitudinal sectional view schematically showing a first example of a film forming apparatus capable of carrying out a silicon nitride film forming method according to an embodiment of the present invention; Horizontal sectional view of the film forming apparatus shown in FIG. Horizontal sectional view schematically showing a second example of a film forming apparatus capable of performing the silicon nitride film forming method according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. Note that common parts are denoted by common reference numerals throughout the drawings.

(First embodiment)
<Method for forming silicon nitride film>
1 is a flowchart showing an example of a sequence of a method for forming a silicon nitride film according to the first embodiment of the present invention, FIG. 2 is a time chart of the sequence shown in FIG. 1, and FIGS. 3A to 3F are FIG. It is sectional drawing which shows roughly the state of the to-be-processed object in the sequence to show.

First, as shown in Step 1 in FIG. 1 and FIG. 3A, the object to be processed is carried into the processing chamber 101 of the film forming apparatus. In this example, the object to be processed is a silicon wafer (hereinafter referred to as a wafer) 1 on which a silicon oxide film 2 is formed. An example of the silicon oxide film 2 is a SiO ₂ film. After the wafer 1 is loaded into the processing chamber 101, the processing chamber 101 is evacuated (t0 to t1 in FIG. 2), and the inside of the processing chamber 101 is subsequently purged with an inert gas (t1 to t2 in FIG. 2). ). An example of the inert gas is nitrogen (N ₂ ) gas.

  Next, as shown in Step 2 in FIG. 1 and FIG. 3B, the silicon source gas and the nitriding gas are simultaneously supplied to the processing chamber 101 (t2 to t3 in FIG. 2). The supply of the silicon source gas and the nitriding gas is performed in a state where the opening degree of the valve V provided in the exhaust pipe connecting the exhaust port 129 of the processing chamber 101 and the exhaust device is reduced or the valve V is closed. . 2 and 3B show a state where the valve V is closed. Examples of the valve V include an exhaust main valve, a pressure adjustment valve capable of adjusting an opening degree, and the like. An example of the silicon source gas is dichlorosilane (DCS). As the nitriding agent contained in the nitriding gas, a nitrogen-containing heterocyclic compound gas is used in the present embodiment. An example of the nitrogen-containing heterocyclic compound gas is 1H-1,2,3-triazole.

An example of the processing conditions of Step 2 is
DCS flow rate: 1 slm
Triazole flow rate: 300sccm
Processing time: 11 sec
Processing temperature: 380 ℃
Processing pressure: Increase from 133.3 Pa to 533.2 Pa
(Rising from 1 Torr to 4 Torr)
(In this specification, 1 Torr is defined as 133.3 Pa.)
It is. In Step 2, in this example, the inert gas is continuously supplied at a predetermined flow rate, but the supply of the inert gas can be stopped. Although cites 380 ° C. An example of the processing temperature, because in this example used nitrogen-containing heterocyclic compound gas as a nitriding gas, for example, as compared to the nitriding gas such as NH _3, more silicon nitride at a low temperature A film can be formed. The film forming temperature range is around 380 ° C., 180 ° C. or more and less than 600 ° C., more preferably 200 ° C. or more and 550 ° C. or less. Therefore, the treatment temperature may be selected from a temperature range of 180 ° C. or higher and lower than 600 ° C., more preferably selected from a temperature range of 200 ° C. or higher and 550 ° C. or lower.

  Next, as shown in Step 3 and FIG. 3C in FIG. 1, the supply of the silicon source gas and the nitriding gas is stopped while the valve V is closed or the valve V is closed, and the processing chamber is closed. 101 is maintained in a mixed atmosphere of silicon source gas and nitriding gas (t3 to t4 in FIG. 2). As a result, a first silicon nitride layer 3-1 is formed on the surface to be processed of the wafer 1, in this example, the surface of the silicon oxide film 2.

An example of the processing conditions of Step 3 is
Processing time: 74 sec
Processing temperature: 380 ℃
Processing pressure: rising from 533.2 Pa
(Rising from 4 Torr)
It is. In Step 3, in this example, the inert gas is continuously supplied at a predetermined flow rate, but the supply of the inert gas can be stopped. When the supply of the inert gas is stopped, the processing pressure is balanced at about 533.2 Pa.

  Next, as shown in Step 4 and FIG. 3D in FIG. 1, the supply of the silicon source gas, the nitriding gas, and the inert gas is all stopped, and the valve V is opened. Then, the inside of the processing chamber 101 is exhausted by the exhaust device (t4 to t1 in FIG. 2). The steps so far, that is, the time t1 to t1 shown in FIG.

  Next, in step 5 in FIG. 1, it is determined whether or not the number of cycles is a set number. If it is determined that the set number of times is not reached (No), the process returns to Step 2 and Steps 2 to 4 are repeated. As a result, a second silicon nitride layer 3-2 is formed on the surface to be processed of the wafer 1, for example, as shown in FIG. 3E. On the contrary, if it is determined that the set number of times has been reached (Yes), the silicon nitride film forming method according to the first embodiment of the present invention is terminated. By performing such a film forming method on the surface to be processed of the wafer 1, as shown in FIG. 3F, the silicon nitride film 3 having the designed film thickness T is formed on the surface to be processed of the wafer 1. Is deposited.

According to the silicon nitride film forming method according to the first embodiment, first, a nitrogen-containing heterocyclic compound gas is used as a nitriding agent contained in the nitriding gas. For this reason, it is possible to lower the film forming temperature range as compared with the case where only NH ₃ gas is used as the nitriding gas. For example, the film forming temperature range can be lowered to a range of 180 ° C. or higher and lower than 600 ° C., more preferably 200 ° C. or higher and 550 ° C. or lower.

  In addition, by using a nitrogen-containing heterocyclic compound gas as a nitriding agent, even if a silicon nitride film is formed using only thermal activation without using plasma, it is equivalent to the case using plasma. It is possible to ensure a film forming rate. One reason for this is as follows.

Nitrogen-containing heterocyclic compound gases, for example, 1H-1,2,3-triazole compounds, contain “N═N—N” bonds in the five-membered ring. The portion of “N = N” in this bond has a property of decomposing to become nitrogen (N ₂ , N≡N). For this reason, 1H-1,2,3-triazole compounds have the property of causing cleavage and decomposition at a number of locations, unlike ordinary ring-opening cleavage. That is, in order to generate “N≡N”, an electronically unsaturated state occurs in the compound. Thus, the decomposition product obtained by cleaving and decomposing 1H-1,2,3-triazole compounds is active. Therefore, the Si film can be nitrided even when the film formation temperature is low, for example, in a temperature range of 200 ° C. or higher and 550 ° C. or lower.

  Moreover, in the silicon nitride film forming method according to the first embodiment, the silicon source gas and the nitriding gas are simultaneously supplied into the processing chamber 101 as described in Step 2. For this reason, compared with the case where silicon source gas and nitriding gas are alternately supplied into the processing chamber 101, there is also an advantage that the deposition rate of the silicon nitride film can be further improved. Can do.

  Therefore, according to the method for forming a silicon nitride film according to the first embodiment, it is possible to further improve the film formation rate, and it is sufficient even if the nitriding agent is only thermally activated. It is possible to obtain a silicon nitride film forming method capable of obtaining a sufficient nitriding power.

(Second Embodiment)
<Method for forming silicon nitride film>
4 is a flowchart showing an example of a sequence of a silicon nitride film forming method according to the second embodiment of the present invention, FIG. 5 is a time chart of the sequence shown in FIG. 4, and FIGS. 6A and 6B are FIG. It is sectional drawing which shows roughly the state of the to-be-processed object in the sequence to show.

  The silicon nitride film forming method according to the second embodiment is different from the silicon nitride film forming method according to the first embodiment in that nitriding contains a nitrogen-containing heterocyclic compound gas as a nitriding agent. In addition to the gas, another nitriding gas containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas is used as a nitriding agent.

That is, as shown in step 2a in FIG. 4 and FIG. 6A, silicon source gas, nitriding gas, and other nitriding gases are simultaneously supplied to the processing chamber 101 (t2 to t3 in FIG. 5). Also in this example, step 2a is performed in a state where the opening degree of the valve V is reduced or in a state where the valve V is closed. FIG. 6A shows a state in which the valve V is closed. An example of the silicon source gas is DCS, an example of the nitriding agent contained in the nitriding gas is 1H-1,2,3-triazole, and an example of the nitriding agent contained in the other nitriding gas is NH ₃ gas.

An example of the processing conditions of step 2a is
DCS flow rate: 1 slm
Triazole flow rate: 300sccm
NH ₃ flow rate: 1 slm
Processing time: 11 sec
Processing temperature: 380 ℃
Processing pressure: Increase from 133.3 Pa to 533.2 Pa
(Rising from 1 Torr to 4 Torr)
It is. In step 2a, in this example, the inert gas may be continuously supplied at a predetermined flow rate or may be stopped. The processing temperature is not limited to 380 ° C., and is selected from a temperature range of 200 ° C. or more and 550 ° C. or less as in the first embodiment.

  Next, as shown in Step 3a and FIG. 6B in FIG. 4, the silicon source gas, the nitriding gas, and the other nitriding gases are kept in a state in which the opening of the valve V is reduced or the valve V is closed. The supply is stopped and the inside of the processing chamber 101 is held in a mixed atmosphere of a silicon source gas, a nitriding gas, and another nitriding gas (t3 to t4 in FIG. 5). As a result, the first silicon nitride layer 3-1 is formed on the surface to be processed of the wafer 1, in this example, on the surface of the silicon oxide film 2, as in the first embodiment.

  The processing conditions of step 3a may be the same conditions as in step 3 of the first embodiment. After step 3a, the process proceeds to step 4 shown in FIG. 1, and the silicon nitride film forming method according to the first embodiment is followed.

  According to the silicon nitride film forming method according to the second embodiment, the same advantages as those of the first embodiment can be obtained. Further, a nitriding gas containing a nitrogen-containing heterocyclic compound gas as a nitriding agent and another nitriding gas containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas as a nitriding agent are simultaneously treated with the silicon source gas. 101 is supplied. For this reason, the further advantage that the deposition rate of the silicon nitride film can be further improved can be further obtained. A detailed film forming rate will be described later.

In the second embodiment, as the nitriding agent contained in other nitriding gas, N ₂ O, NO, NO ₂ or the like can be used in addition to the above NH ₃ .

(Third embodiment)
<Method for forming silicon nitride film>
7 is a flowchart showing an example of a sequence of a silicon nitride film forming method according to the third embodiment of the present invention, FIG. 8 is a time chart of the sequence shown in FIG. 7, and FIG. 9 is in the sequence shown in FIG. It is sectional drawing which shows the state of this to-be-processed object roughly.

  The silicon nitride film forming method according to the third embodiment differs from the silicon nitride film forming method according to the first and second embodiments in that the inside of the processing chamber 101 is nitrided with silicon source gas. After holding in a mixed atmosphere with a gas or another nitriding gas (step 3 or step 3a), the inside of the processing chamber 101 is purged with an inert gas (period t4 to t5 shown in FIG. 8). Thereafter, as shown in Step 6 and FIG. 9 in FIG. 7, in the processing chamber 101, the silicon nitride film (for example, the first silicon nitride layer 3-1) obtained on the surface to be processed is Further nitriding.

In this example, nitriding in step 6 is performed using plasma assist. Further, as the nitriding gas used for nitriding, other nitriding gases are used. In this example, the other nitriding gas contains NH ₃ gas as a nitriding agent. In step 6, plasma assist is “ON”, for example, high frequency power is applied between the electrodes. Plasma is generated when NH ₃ gas passes between electrodes to which high-frequency power is applied.

By activating the NH ₃ gas with plasma in this way, other nitriding gases become gases containing active species such as nitrogen radicals (N ^* ) and ammonia radicals (NH ^* ), and enter the processing chamber 101. Supplied. A silicon nitride film formed on the surface to be processed of the wafer 1, for example, the first silicon nitride layer 3-1 shown in FIG. 9 is activated by active nitrogen radicals (N ^* ) or ammonia radicals (NH ^* ). Further, nitriding is performed. Note that step 6 is performed with the valve V opened, for example.

  Next, the process chamber is evacuated as shown in Step 4 of FIG. Thereafter, a silicon nitride film is formed according to the sequence shown in FIG. 1 or the sequence shown in FIG.

  According to the silicon nitride film forming method according to the third embodiment, the same advantages as those of the first and second embodiments can be obtained. Further, after the inside of the processing chamber 101 is held in a mixed atmosphere of a silicon source gas and a nitriding gas or another nitriding gas (step 3 or step 3a), the silicon nitride film is further nitrided as shown in step 6 . Therefore, an advantage that the deposition rate of the silicon nitride film can be further improved as compared with the first and second embodiments can be obtained.

Further, as the nitriding gas shown in Step 6, other nitriding gases can be used, and as the nitriding agent, NH ₃ , N ₂ O, NO, NO ₂ or the like can be used. Further, when plasma assist is used for nitriding, N ₂ gas can be used as a nitriding agent.

<Silicon nitride film deposition rate>
FIG. 10 is a diagram showing the deposition rate per cycle of the silicon nitride film. FIG. 10 shows the deposition rate of the silicon nitride film in the following three cases.

(A) Comparative Example Silicon source gas (DCS) and nitriding gas (1H-1H-1,2,3-triazole compound) are alternately supplied to the processing chamber.
(B) Second Embodiment A silicon source gas (DCS), a nitriding gas (1H-1H-1,2,3-triazole compound) and another nitriding gas (NH ₃ ) are simultaneously supplied to the processing chamber.
(C) Third Embodiment A silicon source gas (DCS), a nitriding gas (1H-1H-1,2,3-triazole compound) and another nitriding gas (NH ₃ ) are simultaneously supplied to the processing chamber, Further nitriding

  In the case of the comparative example, the film formation rate per cycle was 0.005 nm / cycle, but in the case of the second embodiment, the film formation rate per cycle was 0.038 nm / cycle, which is compared with the comparative example. As a result, the film forming rate was improved about 8 times.

  In the case of the third embodiment, the film formation rate per cycle was 0.149 nm / cycle, and the film formation rate was improved about 30 times compared to the comparative example. In addition, compared with the second embodiment, the film formation rate was improved about 4 times.

  In addition, although the film-forming rate in the case of 1st Embodiment is not shown, the difference from a comparative example is silicon source gas (DCS) and nitriding gas (1H-1H-1,2,3-triazole type compound) Are alternately supplied to the processing chamber or simultaneously.

  In the first embodiment, since the silicon source gas (DCS) and the nitriding gas (1H-1H-1,2,3-triazole compound) are simultaneously supplied to the processing chamber, the film formation rate is higher than that of the comparative example. improves. Therefore, it is estimated that the film formation rate in the case of the first embodiment is between the comparative example and the second embodiment, that is, in the range of more than 0.005 nm / cycle and less than 0.038 nm / cycle. can do.

<Wet etching resistance>
Next, the wet etching resistance of various films will be described.

  Strictly speaking, the silicon nitride film 3 formed according to the first to third embodiments, in addition to silicon atoms (Si) and nitrogen atoms (N), oxygen atoms (O) and carbon atoms (C). It becomes the SiOCN film | membrane further containing these. “O” in the SiOCN film is derived from, for example, O atoms adsorbed on the surface to be processed or O atoms contained in the silicon oxide film on the surface to be processed, and “C” is a nitrogen-containing heterocyclic compound gas. Derived from the C atom of the included alkyl group. FIG. 11 shows the film composition of the silicon nitride film 3 formed according to the second embodiment.

  As shown in FIG. 11, the film composition of the silicon nitride film 3 formed according to the second embodiment is as follows: Si: 30.2 at%, O: 26.9 at%, C: 16.7 at%, N: It was 26.3 at%. Thus, the silicon nitride film 3 contains, for example, about 26 to 27 at% of O atoms and about 16 to 17 at% of C atoms. The total value of the film composition is 100.1%, which is due to rounding off.

  For example, when C atoms are taken into the silicon nitride film 3, the etching rate of the silicon nitride film 3 changes. In general, the etching tends to be difficult when the proportion of C atoms in the silicon nitride film 3 is increased, and is easily etched when the proportion is lower.

FIG. 12 is a diagram showing an etching rate with respect to 0.5% diluted hydrofluoric acid. FIG. 12 shows the etching rates in the following three cases.
(D) Silicon oxide film (SiO ₂ film formed using ALD method; hereinafter abbreviated as SiO ₂ film)
(E) Silicon nitride film (SiN film formed using ALD method; hereinafter abbreviated as SiN film)
(F) Silicon nitride film (SiOCN film formed according to the second embodiment; hereinafter abbreviated as SiOCN film)

As shown in FIG. 12, in the wet etching using 0.5% diluted hydrofluoric acid, the SiO ₂ film is etched by about 30 nm per minute. The SiN film is etched by about 12 to 13 nm per minute. That is, there is an etching rate difference of about 17 to 18 nm per minute between the SiO ₂ film and the SiN film (a silicon nitride film containing no or almost no C).

With respect to these SiO ₂ film and SiN film, the silicon nitride film formed according to the second embodiment, that is, the SiOCN film, is etched only about 2 to 3 nm per minute. For this reason, the SiOCN film has a large etching rate difference of about 27 to 28 nm per minute with respect to the SiO ₂ film. Furthermore, the SiOCN film also has an etching rate difference of about 10 nm per minute with respect to the SiN film.

  Thus, according to the silicon nitride film formed according to the method of forming a silicon nitride film according to the second embodiment, for example, it is difficult to etch with respect to 0.5% dilute hydrofluoric acid. Is obtained. This is because a nitrogen-containing heterocyclic compound gas is used as a nitriding agent contained in the nitriding gas, so that the C atom of the alkyl group contained in the nitrogen-containing heterocyclic compound gas is taken into the silicon nitride film. It is presumed that this is because of this.

Therefore, according to the silicon nitride film formation method according to the first to third embodiments, the film formation rate can be improved as described above, and the formed silicon nitride film 3 A large etching rate difference of about 27 to 28 nm per minute with respect to the SiO ₂ film, and an etching rate difference of about 10 nm per minute with respect to the SiN film containing no or almost no C atoms. The advantage that it can be provided can also be obtained.

<Nitrogen-containing heterocyclic compound>
Next, the nitrogen-containing heterocyclic compound that can be used in the embodiment of the present invention will be described.

Examples of nitrogen-containing heterocyclic compound gas that can be used in the embodiment of the present invention include:
Triazole compound (FIG. 13A)
Oxatriazole compound (FIG. 13B)
Tetrazole compound (FIG. 13C)
Triazine compound (FIG. 13D)
Tetrazine compound (FIG. 13E: 1,2,3,4-tetrazine compound, FIG. 3F: 1,2,3,5-tetrazine compound)
Benzotriazole compounds (Figure 13G)
Benzotriazine compounds (Figure 13H)
Benzotetrazine compounds (FIG. 13I)
Examples thereof include a gas containing at least one of the following.

However, in the formulas shown in FIGS. 13A to 13I, R ^{4 to} R ⁸ are each a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent. .

As the linear or branched alkyl group having 1 to 8 carbon atoms,
Methyl group ethyl group n-propyl group isopropyl group n-butyl group isobutyl group t-butyl group n-pentyl group isopentyl group t-pentyl group n-hexyl group isohexyl group t-hexyl group n-heptyl group isoheptyl group t-heptyl group An n-octyl group, an isooctyl group, a t-octyl group, etc. can be mentioned. In the above alkyl group, a methyl group, an ethyl group, and an n-propyl group are preferable for practical use. More preferred is a methyl group.

The substituent may be a linear or branched monoalkylamino group or dialkylamino group substituted with an alkyl group having 1 to 4 carbon atoms. Specifically, it is a monomethylamino group, a dimethylamino group, a monoethylamino group, a diethylamino group, a monopropylamino group, a monoisopropylamino group, or an ethylmethylamino group. Practically, a monomethylamino group and a dimethylamino group are preferable. More preferred is a dimethylamino group.

Further, the substituent may be a linear or branched alkoxy group having 1 to 8 carbon atoms. Specifically, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group. Practically, a methoxy group, an ethoxy group, and a propoxy group are preferable. More preferably, it is a methoxy group.

For example, the nitrogen-containing heterocyclic compound gas represented by the formula shown in FIG. 13A is a gas containing a 1,2,3-triazole-based compound. As specific examples of 1,2,3-triazole compounds,
1H-1,2,3-triazole 1-methyl-1,2,3-triazole 1,4-dimethyl-1,2,3-triazole 1,4,5-trimethyl-1,2,3-triazole 1- Examples include ethyl-1,2,3-triazole 1,4-diethyl-1,2,3-triazole 1,4,5-triethyl-1,2,3-triazole. In addition, you may use a 1,2,3-triazole type compound individually or in mixture of 2 or more types.

  Note that the oxatriazole compound (FIG. 13B), the tetrazole compound (FIG. 13C), the triazine compound (FIG. 13D), the tetrazine compound (FIGS. 13E and 13F), the benzotriazole compound (FIG. 13G), and the benzotriazine system. Specific examples of the compound (FIG. 13H) and the benzotetrazine compound (FIG. 13I) are not shown, but it goes without saying that there are various specific examples such as triazole compounds.

<Film forming apparatus: first example>
Next, a first example of a film forming apparatus capable of carrying out the silicon nitride film forming method according to the embodiment of the present invention will be described.

  FIG. 14 is a longitudinal sectional view schematically showing a first example of a film forming apparatus capable of carrying out the silicon nitride film forming method according to the embodiment of the present invention, and FIG. 15 is a film forming shown in FIG. It is a horizontal sectional view of an apparatus.

  As shown in FIGS. 14 and 15, the film forming apparatus 100 includes a cylindrical processing chamber 101 having a ceiling with a lower end opened. The entire processing chamber 101 is made of, for example, quartz. A quartz ceiling plate 102 is provided on the ceiling in the processing chamber 101. For example, a manifold 103 formed in a cylindrical shape from stainless steel is connected to a lower end opening of the processing chamber 101 via a seal member 104 such as an O-ring.

  The manifold 103 supports the lower end of the processing chamber 101. A vertical wafer boat 105 is inserted into the processing chamber 101 from below the manifold 103. The vertical wafer boat 105 has a plurality of rods 106 in which a plurality of support grooves (not shown) are formed, and a plurality of, for example, 50 to 100 semiconductor substrates as objects to be processed in the support grooves, In this example, a part of the peripheral edge of the wafer 1 is supported. As a result, the wafers 1 are placed in multiple stages on the vertical wafer boat 105.

  The vertical wafer boat 105 is placed on a table 108 via a quartz heat insulating cylinder 107. The table 108 is supported on a rotating shaft 110 that opens and closes a lower end opening of the manifold 103 and penetrates a lid portion 109 made of, for example, stainless steel. For example, a magnetic fluid seal 111 is provided in the penetrating portion of the rotating shaft 110 and supports the rotating shaft 110 so as to be rotatable while hermetically sealing. Between the peripheral part of the cover part 109 and the lower end part of the manifold 103, for example, a seal member 112 made of an O-ring is interposed. Thereby, the sealing performance in the processing chamber 101 is maintained. The rotating shaft 110 is attached to the tip of an arm 113 supported by an elevating mechanism (not shown) such as a boat elevator, for example. As a result, the vertical wafer boat 105, the lid 109, and the like are integrally moved up and down and inserted into and removed from the processing chamber 101.

  The film forming apparatus 100 includes a processing gas supply mechanism 114 that supplies a gas used for processing in the processing chamber 101. The processing gas supply mechanism 114 of this example includes a silicon source gas supply source 117a, a nitriding gas supply source 117b, another nitriding gas supply source 117c, and an inert gas supply source 117d.

The silicon source gas supplied from the silicon source gas supply source 117a is used in step 2 shown in FIG. 1, and an example thereof is DCS gas. The nitriding gas supplied from the nitriding gas supply source 117b is used in Step 2 shown in FIG. 1, and an example thereof is 1H-1,2,3-triazole gas. Another nitriding gas supplied from another nitriding gas supply source 117c is used in step 2a shown in FIG. 4 or step 6 shown in FIG. 7, and an example thereof is NH ₃ gas. The inert gas supplied from the inert gas supply source 117d is used for dilution of the gas supplied into the processing chamber 101, purge processing, and the like, and an example thereof is N ₂ gas.

  The silicon source gas supply source 117a is connected to the dispersion nozzle 123a via the flow rate controller 121a and the on-off valve 122a. Further, the nitriding gas supply source 117b is connected to the dispersion nozzle 123b (not shown in FIG. 14, see FIG. 15) via the flow rate controller 121b and the on-off valve 122b. The other nitriding gas supply source 117c is connected to the dispersion nozzle 123c via the flow rate controller 121c and the on-off valve 122c. The inert gas supply source 117d is connected to the nozzle 128 via the flow rate controller 121d and the on-off valve 122d. The nozzle 128 passes through the side wall of the manifold 103 and discharges an inert gas from the tip thereof in the horizontal direction.

  The dispersion nozzles 123a to 123c are made of quartz tubes, penetrate the sidewalls of the manifold 103 inward, are bent upward, and extend vertically. A plurality of gas discharge holes 124 are formed at predetermined intervals in the vertical portions of the dispersion nozzles 123a to 123c. As a result, each gas is ejected from the gas ejection holes 124 in the horizontal direction into the processing chamber 101 substantially uniformly.

A plasma generation mechanism 140 is formed on a part of the side wall of the processing chamber 101. The plasma generation mechanism 140 applies energy to other nitriding gases so that active species such as nitrogen radicals N ^* and ammonia radicals NH ^* are generated. The plasma generation mechanism 140 includes a plasma partition wall 141 that is airtightly welded to the outer wall of the processing chamber 101. The plasma partition wall 141 is made of, for example, quartz. The plasma partition wall 141 has a concave shape in cross section, and covers the opening 142 formed in the side wall of the processing chamber 101. The opening 142 is elongated in the vertical direction so that all the wafers 1 supported by the vertical wafer boat 105 can be covered in the vertical direction. For example, the opening 142 is formed by scraping the side wall of the processing chamber 101. In this example, a dispersion nozzle 123c that discharges another nitriding gas is disposed in the inner space defined by the plasma partition wall 141, that is, in the plasma generation space.

The plasma generating mechanism 140 supplies power to a pair of elongated plasma electrodes 143 disposed on the outer surfaces of both side walls of the plasma partition wall 141 so as to face each other in the vertical direction, and for example, to each of the pair of plasma electrodes 143. A high-frequency power source 145 that is connected via a line 144 and supplies high-frequency power to the pair of plasma electrodes 143 is provided. The high frequency power source 145 applies a high frequency voltage of 13.56 MHz, for example, to the pair of plasma electrodes 143. As a result, a high frequency electric field is applied to the plasma generation space defined by the plasma partition wall 141. The nitriding gas discharged from the dispersion nozzle 123c is turned into plasma in a plasma generation space to which a high-frequency electric field is applied. For example, the opening 142 is used as a plasma gas containing active species such as nitrogen radicals N ^* and ammonia radicals NH ^*. To the inside of the processing chamber 101. In the film forming apparatus 100, if the supply of high-frequency power to the pair of plasma electrodes 143 is stopped, the nitriding gas discharged from the dispersion nozzle 123c may be supplied into the processing chamber 101 without being converted into plasma. Is possible.

  An insulating protective cover 146 made of, for example, quartz is attached to the outside of the plasma partition wall 141 so as to cover it. A refrigerant passage (not shown) is provided in the inner portion of the insulating protective cover 146. For example, the plasma electrode 143 can be cooled by flowing a cooled nitrogen gas.

  An exhaust port 129 for exhausting the inside of the processing chamber 101 is provided in a side wall portion of the processing chamber 101 located on the opposite side to the dispersion nozzles 123a to 123c. The exhaust port 129 is formed in an elongated shape by scraping the side wall of the processing chamber 101 in the vertical direction. An exhaust port cover member 130 having a U-shaped cross section so as to cover the exhaust port 129 is attached to a portion corresponding to the exhaust port 129 of the processing chamber 101 by welding. The exhaust port cover member 130 extends upward along the side wall of the processing chamber 101, and defines a gas outlet 131 above the processing chamber 101. An exhaust mechanism 132 including a vacuum pump or the like is connected to the gas outlet 131 via a valve V. The exhaust mechanism 132 exhausts the inside of the processing chamber 101 to set the exhaust of the processing gas used for the processing and the pressure in the processing chamber 101 to a processing pressure corresponding to the processing.

  A cylindrical heating device 133 is provided on the outer periphery of the processing chamber 101. The heating device 133 activates the gas supplied into the processing chamber 101 and heats the target object accommodated in the processing chamber 101, in this example, the wafer 1.

  Control of each part of the film forming apparatus 100 is performed by a controller 150 including, for example, a microprocessor (computer). Connected to the controller 150 is a user interface 151 including a touch panel on which an operator inputs commands to manage the film forming apparatus 100, a display for visualizing and displaying the operating status of the film forming apparatus 100, and the like. Yes.

  A storage unit 152 is connected to the controller 150. The storage unit 152 is a control program for realizing various processes executed by the film forming apparatus 100 under the control of the controller 150, and for causing each component of the film forming apparatus 100 to execute processes according to the processing conditions. A program, i.e. a recipe, is stored. The recipe is stored in a storage medium in the storage unit 152, for example. The storage medium may be a hard disk or a semiconductor memory, or a portable medium such as a CD-ROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example. The recipe is read from the storage unit 152 according to an instruction from the user interface 151 as necessary, and the controller 150 executes processing according to the read recipe. Under the control of 150, a desired process is performed.

  The silicon nitride film forming method according to the first to third embodiments uses the film forming apparatus 100 as shown in FIGS. 14 and 15 and the controller 150 changes the first to third embodiments. The silicon source gas supply source 117a, the nitriding gas supply source 117b, the other nitriding gas supply source 117c, the exhaust mechanism 132, the heating device 133, the valve V, and the third so that the silicon nitride film forming method is executed. In the case of this embodiment, the plasma generation mechanism 140 can be further controlled.

  When only the silicon nitride film forming method according to the first and second embodiments is performed, the plasma generation mechanism 140 can be removed from the film forming apparatus 100.

<Deposition system: second example>
FIG. 16 is a horizontal cross-sectional view schematically showing a second example of a film forming apparatus capable of carrying out the silicon nitride film forming method according to the embodiment of the present invention.

  The film forming apparatus is not limited to the vertical batch type as shown in FIGS. For example, a horizontal batch type as shown in FIG. 16 may be used. FIG. 16 schematically shows a horizontal cross section of a processing chamber of a horizontal batch type film forming apparatus 200. In FIG. 16, illustration of a processing gas supply mechanism, an exhaust device, a heating device, a controller, and the like is omitted.

  As illustrated in FIG. 16, the film forming apparatus 200 places, for example, five wafers 1 on the turntable 201 and performs film forming processing on the five wafers 1. The turntable 201 is rotated clockwise, for example, with the wafer 1 placed thereon. The processing chamber 202 of the film forming apparatus 200 is divided into four processing stages. When the turntable 201 rotates, the wafer 1 rotates around the four processing stages in order.

  The first processing stage PS1 is a stage for performing Steps 2 and 3 shown in FIG. 1 or Steps 2a and 3a shown in FIG. In this example, steps 2a and 3a shown in FIG. 4 are performed. In the processing stage PS1, the silicon raw material gas, the nitriding gas, and another nitriding gas are simultaneously supplied onto the surface to be processed of the wafer 1. For example, on the upstream side of the processing stage PS1, a gas supply pipe 203a that supplies a silicon source gas, a gas supply pipe 203b that supplies a nitriding gas, and a gas supply pipe 203c that supplies another nitriding gas are arranged. . The gas supply pipes 203a to 203c supply a silicon raw material gas, a nitriding gas, and other nitriding gases toward the surface to be processed of the wafer 1 that has been mounted on the turntable 201. An exhaust port 204 is provided on the downstream side of the processing stage PS1. While the wafer 1 is moving on the processing stage PS1, the atmosphere in the stage PS1 is a mixed atmosphere of a silicon source gas, a nitriding gas, and another nitriding gas, whereby step 3 is performed.

  The processing stage PS1 is also a loading / unloading stage for loading / unloading the wafer 1 into / from the processing chamber 202. The wafer 1 is carried into and out of the processing chamber 202 via a wafer carry-in / out opening 205. The carry-in / out port 205 is opened and closed by a gate valve 206. The next stage after the processing stage PS1 is the processing stage PS2.

  For example, the processing stage PS2 is a stage in which the purge process is performed during the period t4 to t5 shown in FIG. The processing stage PS2 is a narrow space, and the wafer 1 passes through the narrow space while being placed on the turntable 201. An inert gas is supplied from the gas supply pipe 207 into the narrow space. The process stage PS3 is followed by the process stage PS3.

The processing stage PS3 is a stage that performs Step 6 shown in FIG. A gas supply pipe 208 and a plasma generation mechanism 211 are disposed above the processing stage PS3. The gas supply pipe 208 supplies another nitriding gas toward the surface to be processed of the wafer 1 that has been mounted on the turntable 201. Furthermore, the plasma generation mechanism 211 applies energy to the supplied nitriding gas so that active species such as nitrogen radicals N ^* and ammonia radicals NH ^* are generated. An exhaust port 209 is provided on the downstream side of the processing stage PS3. Next to the processing stage PS3 is the processing stage PS4.

  The processing stage PS4 is a stage in which the purge process is performed during the periods t1 to t2 shown in FIG. The processing stage PS4 is a narrow space like the processing stage PS2, and the wafer 1 passes through the narrow space while being placed on the turntable 201. An inert gas is supplied from a gas supply pipe 210 into the narrow space. After the processing stage PS4, the process returns to the first processing stage PS1.

  Thus, in the film forming apparatus 200, for example, Step 1 to Step 4 shown in FIG. With the wafer 1 mounted on the turntable 201, the silicon nitride film is formed on the surface to be processed of the wafer 1 by rotating the wafer 1 up to a set number of times. In this example, the silicon nitride film is formed as described in the third embodiment. The film can be formed according to the film method.

  The silicon nitride film forming methods according to the first to third embodiments of the present invention can also be carried out by using a film forming apparatus 200 as shown in FIG.

  In the case where only the silicon nitride film forming method according to the first and second embodiments is performed, the processing stages PS2 and PS3 may be omitted from the film forming apparatus 200.

  As mentioned above, although this invention was demonstrated by 1st-3rd embodiment, this invention is not restricted to the said 1st-3rd embodiment, In the range which does not deviate from the meaning, it deform | transforms variously. It is possible to implement.

  For example, in the above embodiment, the processing conditions are specifically exemplified, but the processing conditions are not limited to the above specific examples. For example, the gas flow rate and the like can be appropriately adjusted according to the volume of the processing chamber.

  Moreover, although it is silicon source gas, although DCS gas was used in the said embodiment, it is not restricted to DCS gas, It is also possible to use chlorosilane type gas other than DCS. Furthermore, it is not limited to chlorosilane-based gas, and higher-order chlorosilane-based gas higher than chlorodisilane can also be used. Of course, other than the chlorosilane-based gas, a silane-based gas not containing chlorine or a higher-order silane-based gas higher than disilane may be used.

  In addition, the present invention can be variously modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 ... Silicon wafer, 2 ... Silicon oxide film, 3 ... Silicon nitride film, 3-1 ... 1st layer silicon nitride layer, 3-2 ... 2nd layer silicon nitride layer.

Claims (11)

A silicon nitride film forming method for forming a silicon nitride film on a processing surface of an object to be processed,
(1) carrying the object to be processed into a processing chamber of a film forming apparatus;
(2) supplying a silicon source gas and a nitriding gas simultaneously to the processing chamber;
(3) maintaining the processing chamber in a mixed atmosphere of the silicon source gas and the nitriding gas;
(4) exhausting the processing chamber;
Comprising
Steps (2) to (4) are repeated for a set number of times.
The method for forming a silicon nitride film, wherein the nitriding gas contains a nitrogen-containing heterocyclic compound gas as a nitriding agent.   In the step (2), another nitriding gas containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas is further supplied as a nitriding agent into the processing chamber. A method for forming a silicon nitride film as described. After the step (3),
(5) The method further includes a step of further nitriding the silicon nitride film obtained on the surface to be processed in the processing chamber,
2. The method for forming a silicon nitride film according to claim 1, wherein the steps (2) to (5) are repeated a set number of times. In the step (2), another nitriding gas containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas as a nitriding agent in the processing chamber of the film forming apparatus in which the object to be processed is accommodated, Supply
4. The method of forming a silicon nitride film according to claim 3, wherein in the step (5), the other nitrogen gas is supplied into a processing chamber of a film forming apparatus in which the object to be processed is accommodated. .   5. The method of forming a silicon nitride film according to claim 4, wherein in the step (5), the nitrogen compound gas contained in the other nitriding gas is activated by plasma.   6. The method of forming a silicon nitride film according to claim 5, wherein the other nitriding gas contains nitrogen gas instead of the nitrogen compound gas.   The step (2) and the step (3) are performed in a state where the opening degree of a valve connected between the exhaust port of the processing chamber and an exhaust device is reduced or the valve is closed. The method for forming a silicon nitride film according to any one of claims 1 to 6.   8. The silicon nitride according to claim 1, wherein the step (2) and the step (3) are performed in a temperature range of 180 ° C. or higher and lower than 600 ° C. 8. Method for forming a physical film. The nitrogen-containing heterocyclic compound gas is
3. A triazole compound, an oxatriazole compound, a tetrazole compound, a triazine compound, a tetrazine compound, a benzotriazole compound, a benzotriazine compound, and a gas containing at least one of benzotetrazine compounds. The method for forming a silicon nitride film according to claim 8. The nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas is:
NH ₃
N ₂ O
NO
NO ₂
The method for forming a silicon nitride film according to any one of claims 1 to 9, wherein the film is selected from a gas containing at least one of the following. A film forming apparatus for forming a silicon nitride film on a surface to be processed of a target object,
A processing chamber for accommodating the object to be processed;
A processing gas supply mechanism for supplying a gas used for processing into the processing chamber;
A heating device for heating the substrate to be processed accommodated in the processing chamber;
An exhaust mechanism for exhausting the processing chamber through an exhaust port and an exhaust valve;
A controller for controlling the processing gas supply mechanism, the heating device, and the exhaust mechanism,
The said controller controls the said process gas supply mechanism, the said heating apparatus, and the said exhaust mechanism so that the film-forming method of the silicon nitride film as described in any one of Claims 1-10 may be implemented. A film forming apparatus.

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