JP6501560B2 - Method and apparatus for forming silicon nitride film - Google Patents

Description

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

  There is a need for low temperature silicon nitride (SiN) deposition as one of semiconductor device manufacturing processes. The low temperature here indicates a region in which the temperature in the film formation chamber is about 300 to 400 ° C. As a low-temperature SiN film formation method, a combination of a silicon (Si) source gas having good adsorptivity and thermal decomposition in a low-temperature region and a nitriding agent capable of low-temperature nitriding is used.

  A chlorosilane-based gas is known as an Si source gas from which an Si film having good adsorptivity and thermal decomposition properties in a low temperature region and good reactivity as an SiN material can be obtained (see Patent Document 1).

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

Furthermore, Patent Document 1 can improve the deposition rate of the SiN film 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. It is described (see the description etc. of paragraph 0031).

Unexamined-Japanese-Patent No. 2006-49809

In Patent Document 1, by simultaneously supplying DCS and NH ₃ into the processing chamber, the deposition rate of the SiN film can be improved. However, further improvement of 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 sufficient nitriding power only by thermal activation. For this reason, in order to obtain higher nitriding power, radicalization of NH ₃ is used in combination with plasma. However, there is a concern that high frequency power needs to be applied, which may damage the structure of the object to be treated.

  According to the present invention, it is possible to further improve the deposition rate, and a method of depositing a silicon nitride film capable of obtaining sufficient nitriding power even if the nitriding agent is only thermally activated. And a film forming apparatus capable of carrying out the film forming method.

The method for forming a silicon nitride film according to the first aspect of the present invention is a method for forming a silicon nitride film for forming a silicon nitride film on a surface to be processed of an object to be processed. ) Carrying in the processing object into the processing chamber of the film forming apparatus, (2) simultaneously supplying the silicon source gas and the nitriding gas to the processing chamber, (3) in the processing chamber, A process of holding in a mixed atmosphere of a silicon source gas and the nitriding gas, (4) a process of evacuating the processing chamber, and (5) after the process (3), on the processing surface in the processing chamber. And the step of further nitriding the obtained silicon nitride film, and the steps (2) to (5) are repeatedly performed a set number of times, and the nitriding gas is used as a nitriding agent. A nitrogen-containing heterocyclic compound gas is contained, and in the step (2), the object to be treated is collected. In the processing chamber of the deposited film forming apparatus, another nitriding gas containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas is further supplied as a nitriding agent, and in the step (5), The other nitriding gas is supplied into the processing chamber of the film forming apparatus in which the body is accommodated.

  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 surface to be processed of an object to be processed, wherein the processing chamber accommodates 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 housed in the processing chamber, and exhausting the processing chamber through an exhaust port and an exhaust valve An exhaust mechanism, the processing gas supply mechanism, the heating device, and a controller for controlling the exhaust mechanism, the controller performing the method for forming a silicon nitride film according to the first aspect. The process gas supply mechanism, the heating device, and the exhaust mechanism are controlled to be controlled.

  According to the present invention, it is possible to further improve the deposition rate, and it is possible to obtain a silicon nitride film capable of obtaining sufficient nitriding power even if the nitriding agent is only thermally activated. It is possible to provide a film forming method capable of performing the film forming method and the film forming method.

A flow chart showing an example of the sequence of the method for forming a silicon nitride film according to the first embodiment of the present invention The time chart of the sequence shown in Figure 1 FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 2 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. A flow chart showing an example of the sequence of the method for forming a silicon nitride film according to the second embodiment of the present invention The time chart of the sequence shown in FIG. 4 FIG. 5 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. FIG. 5 is a cross sectional view schematically showing the state of the object in the sequence shown in FIG. A flow chart showing an example of the sequence of the method for forming a silicon nitride film according to the third embodiment of the present invention The time chart of the sequence shown in FIG. 7 Sectional view schematically showing the state of the object in the sequence shown in FIG. Diagram showing deposition rate per cycle of silicon nitride film Diagram showing film composition of a silicon nitride film deposited according to the second embodiment Diagram showing the etching rate for 0.5% dilute hydrofluoric acid Figure showing triazole compounds Figure showing oxatriazole compounds Figure showing tetrazole compounds Figure showing triazine compounds Figure showing tetrazine compounds (1,2,3,4-tetrazine compounds) Diagram showing tetrazine compounds (1,2,3,5-tetrazine compounds) Figure showing benzotriazole compounds Figure showing benzo triazine compounds Figure showing benzotetrazine compounds The longitudinal cross-sectional view which shows roughly the 1st example of the film-forming apparatus which can implement the film-forming method of the silicon nitride film which concerns on embodiment of this invention. Horizontal cross-sectional view of the film forming apparatus shown in FIG. A horizontal sectional view schematically showing a second example of a film forming apparatus capable of performing the film forming method of a silicon nitride film according to an embodiment of the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that common parts are denoted by common reference symbols throughout the drawings.

First Embodiment
<Method of forming silicon nitride film>
FIG. 1 is a flow chart showing an example of the sequence of the 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. It is sectional drawing which shows roughly the state of the to-be-processed object in the shown sequence.

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 the present example, the object to be processed is, for example, a silicon wafer 1 (hereinafter referred to as a wafer) having a silicon oxide film 2 formed on its surface. An example of the silicon oxide film 2 is a SiO ₂ film. After the wafer 1 is carried into the processing chamber 101, the inside of 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 an 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 narrowed or the valve V is closed. . 2 and 3B show a state in which the valve V is closed. As an example of the valve V, an exhaust main valve, a pressure control valve whose opening degree can be adjusted, and the like can be mentioned. Further, an example of the silicon source gas is dichlorosilane (DCS). In the present embodiment, a nitrogen-containing heterocyclic compound gas is used as the nitriding agent contained in the nitriding gas. An example of the nitrogen-containing heterocyclic compound gas is 1H-1,2,3-triazole.

An example of the processing condition of step 2 is
DCS flow rate: 1 slm
Triazole flow rate: 300 sccm
Processing time: 11 sec
Processing temperature: 380 ° C
Processing pressure: Rising from 133.3Pa to 533.2Pa
(Up from 1 Torr to 4 Torr)
(In this specification, 1 Torr is defined as 133.3 Pa)
It is. In step 2, the inert gas is continuously supplied at a predetermined flow rate in this example, but it is also possible to stop the supply of the inert gas. In addition, although 380 ° C. is given as an example of the processing temperature, in this example, a nitrogen-containing heterocyclic compound gas is used as a nitriding gas, so silicon nitride at a lower temperature than, for example, a nitriding gas such as NH ₃ . It becomes possible to form a film. The deposition possible temperature zone 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 more and less than 600 ° C., more preferably, a temperature range of 200 ° C. or more and 550 ° C. or less.

  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 throttled down or the valve V is closed, as shown in FIG. The inside of 101 is held in a mixed atmosphere of a silicon source gas and a nitriding gas (t3 to t4 in FIG. 2). Thereby, the first silicon nitride layer 3-1 is formed on the surface to be processed of the wafer 1, which is the surface of the silicon oxide film 2 in this example.

An example of the processing condition of step 3 is
Processing time: 74 seconds
Processing temperature: 380 ° C
Processing pressure: rising from 533.2 Pa
(Up from 4 Torr)
It is. In step 3, the inert gas is continuously supplied at a predetermined flow rate in this example, but it is also possible to stop the supply of the inert gas. When the supply of 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 are 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 up to this point, that is, from time t1 to time t1 shown in FIG. 2 are one cycle.

  Next, in step 5 in FIG. 1, it is determined whether the number of cycles is the set number. If it is determined that the number of times is not set (No), the process returns to step 2 and repeats steps 2 to 4. As a result, for example, as shown in FIG. 3E, the second silicon nitride layer 3-2 is formed on the processing surface of the wafer 1. Conversely, if it is determined that the set number of times (Yes), the silicon nitride film forming method according to the first embodiment of the present invention is ended. By implementing such a film forming method on the surface to be processed of the wafer 1, as shown in FIG. 3F, a silicon nitride film 3 having a designed thickness T on the surface to be processed of the wafer 1 is obtained. Is deposited.

According to the method of forming a silicon nitride film 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 filmable temperature range as compared with the case where only NH ₃ gas is used as the nitriding gas. For example, the temperature range in which the film can be formed can be lowered to a range of 180 ° C. or more and less than 600 ° C., more preferably to a range of 200 ° C. or more and 550 ° C. or less.

  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 using plasma. It becomes possible to secure the deposition rate. As one of the reasons, the following reasons can be mentioned.

The nitrogen-containing heterocyclic compound gas, for example, a 1H-1,2,3-triazole compound contains an "N = N-N" bond in a five-membered ring. Of this bond, the "N = N" portion has the property of decomposing as it becomes nitrogen (N ₂ , N≡N). For this reason, 1H-1,2,3-triazole compounds have the property of causing cleavage and decomposition at a large number of places, unlike ordinary ring-opening cleavage. That is, electronic unsaturation occurs in the compound to produce "N“ N ". Thus, the decomposition product obtained by the cleavage and decomposition of the 1H-1,2,3-triazole compound is active. Therefore, the Si film can be nitrided even in a temperature range where the film forming temperature is low, for example, 200 ° C. or more and 550 ° C. or less.

  Moreover, in the method for forming a silicon nitride film according to the first embodiment, as described in step 2, the silicon source gas and the nitriding gas are simultaneously supplied into the processing chamber 101. Therefore, as compared with the case where the silicon source gas and the nitriding gas are alternately supplied into the processing chamber 101, it is possible to obtain the advantage that the film forming rate of the silicon nitride film can be further improved. Can.

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

Second Embodiment
<Method of forming silicon nitride film>
FIG. 4 is a flow chart showing an example of the sequence of the method for forming a silicon nitride film 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 FIGS. It is sectional drawing which shows roughly the state of the to-be-processed object in the shown sequence.

  The film forming method of the silicon nitride film according to the second embodiment is different from the film forming method of the silicon nitride film according to the first embodiment in that the nitrogen-containing heterocyclic compound gas is contained 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 the nitriding agent.

That is, as shown in step 2a in FIG. 4 and FIG. 6A, the silicon source gas, the nitriding gas and the other nitriding gas 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 narrowed or in a state where the valve V is closed. The state which closed the valve V is shown by FIG. 6A. Further, an example of a silicon source gas an example of a nitriding agent contained DCS, the gas nitriding an example of a nitriding agent contained in the IH-1,2,3-triazole, other nitriding gas is NH ₃ gas.

An example of the processing condition of step 2a is
DCS flow rate: 1 slm
Triazole flow rate: 300 sccm
NH ₃ flow rate: 1 slm
Processing time: 11 sec
Processing temperature: 380 ° C
Processing pressure: Rising from 133.3Pa to 533.2Pa
(Up from 1 Torr to 4 Torr)
It is. In step 2a, the inert gas may be continuously supplied at a predetermined flow rate or may be stopped in this example. The treatment 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, silicon source gas, nitriding gas, and other nitriding gases are used while the valve V is throttled down or the valve V is closed. The supply is stopped, and the inside of the processing chamber 101 is maintained in a mixed atmosphere of a silicon source gas, a nitriding gas, and another nitriding gas (t3 to t4 in FIG. 5). Thereby, the first silicon nitride layer 3-1 is formed on the surface to be processed of the wafer 1, which is the surface of the silicon oxide film 2 in this example, as in the first embodiment.

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

  According to the method for forming a silicon nitride film of the second embodiment, the same advantages as those of the first embodiment can be obtained. Furthermore, a nitriding chamber containing 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 processed with the silicon source gas. Supply in 101. Therefore, it is possible to further obtain the advantage that the film formation rate of the silicon nitride film can be further improved. The detailed deposition rate will be described later.

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

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

  The difference between the method of forming a silicon nitride film according to the third embodiment and the method of forming a silicon nitride film according to the first and second embodiments is that the silicon source gas and the inside of the processing chamber 101 are nitrided 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 in FIG. 7 and FIG. 9, the silicon nitride film (for example, the first silicon nitride layer 3-1) obtained on the surface to be processed in the processing chamber 101 is Further, it is to nitride.

In this example, the nitriding in step 6 is performed using plasma assist. Then, another nitriding gas is used as a nitriding gas used for nitriding. 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. A plasma is generated as NH ₃ gas passes between the electrodes to which high frequency power is applied.

Thus, by activating the NH ₃ gas by plasma, the other nitriding gas becomes a gas containing active species such as nitrogen radicals (N ^* ) and ammonia radicals (NH ^* ), and the like in the processing chamber 101. Supplied. The silicon nitride film formed on the processing surface of the wafer 1, for example, the first silicon nitride layer 3-1 shown in FIG. 9 is formed by active nitrogen radicals (N ^* ) and ammonia radicals (NH ^* ). , Is further nitrided. Step 6 is performed, for example, in a state where the valve V is open.

  Next, as shown in step 4 in FIG. 7, the processing chamber is evacuated, and the process proceeds to step 5. Thereafter, a silicon nitride film is formed in accordance with the sequence shown in FIG. 1 or the sequence shown in FIG.

  According to the method for forming a silicon nitride film of the third embodiment, the same advantages as those of the first and second embodiments can be obtained. Furthermore, after holding the inside of the processing chamber 101 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, as compared with the first and second embodiments, it is possible to obtain an advantage that the deposition rate of the silicon nitride film can be further improved.

Moreover, it is possible to use other nitriding gas as gas for nitriding shown to Step 6, and it is possible to use NH ₃ , N ₂ O, NO, NO ₂ etc. as a nitriding agent. Furthermore, when using plasma assist for nitriding, it is also possible to use N ₂ gas as the nitriding agent.

<Deposition rate of silicon nitride film>
FIG. 10 is a view showing a film forming rate per cycle of a silicon nitride film. FIG. 10 shows the film formation rates of silicon nitride films in the following three cases.

(A) Comparative Example Supplying silicon source gas (DCS) and nitriding gas (1H-1H-1,2,3-triazole compound) alternately 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 a 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 a processing chamber, Furthermore, nitriding

  In the case of the comparative example, the film forming rate per cycle was 0.005 nm / cycle, but in the case of the second embodiment, the film forming rate per cycle is 0.038 nm / cycle, and was compared to the comparative example. The deposition rate was improved about eight times.

  Further, in the case of the third embodiment, the film forming rate per cycle is 0.149 nm / cycle, and the film forming rate is improved by about 30 times as compared with the comparative example. In addition, the film forming rate is improved by about four times as compared with the second embodiment.

  Although the film forming rate in the case of the first embodiment is not shown, the silicon source gas (DCS) and the nitriding gas (1H-1H-1,2,3-triazole compound) are different from the comparative example. And alternately 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 forming rate is higher than that of the comparative example. improves. Therefore, it is estimated that the deposition 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 includes, in addition to silicon atoms (Si) and nitrogen atoms (N), oxygen atoms (O) and carbon atoms (C). And a SiOCN film further containing For example, “O” in the SiOCN film is derived from O atoms adsorbed on the surface to be treated and O atoms contained in the silicon oxide film on the surface to be treated, and “C” is a nitrogen-containing heterocyclic compound gas It originates from C atom of the contained 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. In addition, although the sum total of film composition is 100.1%, this is based on the relationship of 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, when the proportion of C atoms in the silicon nitride film 3 is high, etching tends to be difficult, and on the other hand, when it is low, etching tends to be easy.

FIG. 12 is a diagram showing the etching rate for 0.5% dilute hydrofluoric acid. The etching rates in the following three cases are shown in FIG.
(D) Silicon oxide film (SiO ₂ film formed by ALD method, hereinafter abbreviated as SiO ₂ film)
(E) Silicon nitride film (SiN film formed by 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 about 30 nm per minute. In addition, the SiN film is etched 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 (silicon nitride film containing no or hardly C).

For these SiO ₂ films and SiN films, 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 for the SiN film.

  Thus, according to the silicon nitride film formed according to the method for forming a silicon nitride film according to the second embodiment, for example, the property of being difficult to be etched by 0.5% diluted hydrofluoric acid Is obtained. This is because, by using the nitrogen-containing heterocyclic compound gas as the nitriding agent contained in the nitriding gas, the C atom of the alkyl group contained in the nitrogen-containing heterocyclic compound gas is taken into the film of the silicon nitride film It is presumed that it is because

Therefore, according to the method of forming a silicon nitride film according to the first to third embodiments, the film forming rate can be improved as described above, and in addition to the formed silicon nitride film 3, A large etching rate difference of about 27 to 28 nm per minute for the SiO ₂ film, and an etching rate difference of about 10 nm per minute for the SiN film containing neither C atoms nor C atoms at most. It can be obtained together with the advantage that it can be possessed.

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

Examples of nitrogen-containing heterocyclic compound gases that can be used in the embodiments of the present invention are:
Triazole compounds (FIG. 13A)
Oxatriazole compound (FIG. 13B)
Tetrazole compound (FIG. 13C)
Triazine-based compounds (FIG. 13D)
Tetrazine compounds (FIG. 13E: 1,2,3,4-tetrazine compounds, FIG. 3F: 1,2,3,5-tetrazine compounds)
Benzotriazole compound (FIG. 13G)
Benzotriazine-based compound (FIG. 13H)
Benzotetrazine compounds (FIG. 13I)
And the like.

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

As said C1-C8 linear or branched alkyl group,
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 n-octyl group isooctyl group t-octyl group etc. can be mentioned. Among the above alkyl groups, for practical use, preferred are methyl group, ethyl group and n-propyl group. More preferably, it is a methyl group.

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

Furthermore, as said substituent, a C1-C8 linear or branched alkoxy group may be sufficient. Specifically, they are 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. For practical use, preferred is a methoxy group, an ethoxy group or a propoxy group. More preferably, it is a methoxy group.

Also, 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- Ethyl-1,2,3-triazole 1,4-diethyl-1,2,3-triazole 1,4,5-triethyl-1,2,3-triazole and the like can be mentioned. The 1,2,3-triazole compounds may be used alone or in combination of two or more.

  In addition, oxatriazole compounds (FIG. 13B), tetrazole compounds (FIG. 13C), triazine compounds (FIG. 13D), tetrazine compounds (FIGS. 13E and 13F), benzotriazole compounds (FIG. 13G), benzotriazine compounds Although specific examples of the compound (FIG. 13H) and the benzotetrazine compound (FIG. 13I) are omitted, it goes without saying that there are various concrete examples like triazole compounds.

<Deposition Apparatus: First Example>
Next, a first example of a film forming apparatus capable of performing the film forming method of a silicon nitride film 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 method for forming a silicon nitride film according to an 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 has a cylindrical processing chamber 101 with a ceiling, the lower end of which is open. The entire processing chamber 101 is made of, for example, quartz. On the ceiling in the processing chamber 101, a quartz ceiling plate 102 is provided. At the lower end opening of the processing chamber 101, for example, a manifold 103 formed in a cylindrical shape by stainless steel is connected 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 are processed in the support grooves as objects to be processed, In this example, a part of the peripheral portion of the wafer 1 is supported. Thus, the wafers 1 are mounted on the vertical wafer boat 105 in multiple stages.

  The vertical wafer boat 105 is placed on the table 108 via a quartz heat insulating cylinder 107. The table 108 is supported on a rotating shaft 110 which opens and closes the lower end opening of the manifold 103, for example, through a lid 109 made of stainless steel. For example, a magnetic fluid seal 111 is provided at a penetrating portion of the rotating shaft 110, and the rotating shaft 110 is rotatably supported while being airtightly sealed. A seal member 112 made of, for example, an O-ring is interposed between the peripheral portion of the lid portion 109 and the lower end portion of the manifold 103. Thereby, the sealing performance in the processing chamber 101 is maintained. The rotating shaft 110 is attached to, for example, the tip of an arm 113 supported by an elevating mechanism (not shown) such as a boat elevator. As a result, the vertical wafer boat 105, the lid 109, and the like are integrally lifted and lowered, and are inserted into and removed from the processing chamber 101.

  The film forming apparatus 100 has a processing gas supply mechanism 114 for supplying 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 is the 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 is 1H-1,2,3-triazole gas. The other nitriding gas supplied from the other nitriding gas supply source 117c is used in Step 2a shown in FIG. 4 and Step 6 shown in FIG. 7, one example of which 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, etc. An example 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. Further, 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 117 d is connected to the nozzle 128 via the flow rate controller 121 d and the on-off valve 122 d. The nozzle 128 penetrates the side wall of the manifold 103 and discharges the inert gas horizontally from its tip.

  The dispersion nozzles 123a to 123c are made of quartz tubes and penetrate the side wall of the manifold 103 inwards, 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. Thus, each gas is discharged substantially uniformly from the gas discharge holes 124 into the processing chamber 101 in the horizontal direction.

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 radical N ^* and ammonia radical NH ^* are generated. The plasma generation mechanism 140 includes a plasma compartment wall 141 airtightly welded to the outer wall of the processing chamber 101. The plasma partition wall 141 is formed 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 as to cover all the wafers 1 supported by the vertical wafer boat 105 in the vertical direction, and is formed, for example, by scraping the side wall of the processing chamber 101. In the present 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, inside the plasma generation space.

In the plasma generation mechanism 140, a pair of long and thin plasma electrodes 143 disposed to face each other along the vertical direction on the outer surface of both side walls of the plasma partition wall 141 and, for example, a pair of plasma electrodes 143 are fed. A high frequency power supply 145 connected via a line 144 and supplying high frequency power to the pair of plasma electrodes 143 is provided. The high frequency power supply 145 applies a high frequency voltage of 13.56 MHz, for example, to the pair of plasma electrodes 143. Thereby, a high frequency electric field is applied in the plasma generation space defined by the plasma partition wall 141. The nitriding gas discharged from the dispersion nozzle 123c is plasmatized in the plasma generation space to which the high frequency electric field is applied, and, for example, the opening 142 is a plasma gas containing active species such as nitrogen radical N ^* and ammonia radical NH ^*. Is supplied to the inside of the processing chamber 101 via the In the film forming apparatus 100, when 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 to the inside of the processing chamber 101 without being plasmatized. It is possible.

  An insulating protective cover 146 made of, for example, quartz is attached to the outside of the plasma compartment wall 141 so as to cover it. A refrigerant passage (not shown) is provided on the inner side of the insulating protection cover 146, and 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 elongated by cutting the side wall of the processing chamber 101 in the vertical direction. At a portion corresponding to the exhaust port 129 of the processing chamber 101, an exhaust port cover member 130 having a U-shaped cross section so as to cover the exhaust port 129 is attached 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 and 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, thereby evacuating the processing gas used for the processing and setting 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 object to be processed, which is the wafer 1 in this example, accommodated in the processing chamber 101.

  Control of each part of the film forming apparatus 100 is performed by, for example, a controller 150 including a microprocessor (computer). The controller 150 is connected to a user interface 151 including a touch panel on which an operator operates a command to manage the film forming apparatus 100 and a display for visualizing and displaying the operating condition of the film forming apparatus 100. There is.

  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 by control of the controller 150, and for causing each component of the film forming apparatus 100 to execute the process according to the process condition. The program, ie the recipe, is stored. The recipe is stored, for example, in a storage medium in the storage unit 152. The storage medium may be a hard disk or a semiconductor memory, or may be a portable one such as a CD-ROM, a DVD, a flash memory or the like. Also, the recipe may be properly transmitted from another device, for example, via a dedicated line. 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 a process according to the read recipe. Perform desired processing under control of 150.

  The silicon nitride film forming method according to the first to third embodiments uses the film forming apparatus 100 as shown in FIG. 14 and FIG. 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, the third, and the like so that the film forming method of the silicon nitride film is performed. In the case of the embodiment of FIG.

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

<Deposition Apparatus: Second Example>
FIG. 16 is a horizontal sectional view schematically showing a second example of the film forming apparatus which can carry out the film forming method of the silicon nitride film according to the embodiment of the present invention.

  The film forming apparatus is not limited to the vertical batch type as shown in FIG. 14 and FIG. For example, it may be a horizontal batch type as shown in FIG. FIG. 16 schematically shows a horizontal cross section of the processing chamber of the horizontal batch type film forming apparatus 200. As shown in FIG. In FIG. 16, the process gas supply mechanism, the exhaust device, the heating device, the controller, and the like are not shown.

  As shown in FIG. 16, the film forming apparatus 200 places, for example, five wafers 1 on the turntable 201 and performs a film forming process 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, and the rotation of the turntable 201 causes the wafer 1 to pass through the four processing stages in order.

  The first processing stage PS1 is a stage for performing the steps 2 and 3 shown in FIG. 1 or the 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, simultaneous supply of the silicon source gas, the nitriding gas and the other nitriding gas to the surface to be processed of the wafer 1 is performed. A gas supply pipe 203a for supplying a silicon source gas, a gas supply pipe 203b for supplying a nitriding gas, and a gas supply pipe 203c for supplying another nitriding gas are disposed, for example, on the upstream side of the processing stage PS1. . The gas supply pipes 203 a to 203 c supply a silicon source gas, a nitriding gas, and another nitriding gas toward the processing target surface of the wafer 1 placed and loaded on the turntable 201. An exhaust port 204 is provided downstream 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 the step 3 is performed.

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

  The processing stage PS2 is, for example, a stage for performing a purge process during a 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. Next to the processing stage PS2 is a processing stage PS3.

The processing stage PS3 is a stage for performing 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 processing surface of the wafer 1 placed on the turntable 201 and collected. Furthermore, the plasma generation mechanism 211 applies energy to the supplied nitriding gas so that active species such as nitrogen radical N ^* and ammonia radical NH ^* are generated. An exhaust port 209 is provided downstream of the processing stage PS3. Next to the processing stage PS3 is a processing stage PS4.

  The processing stage PS4 is a stage in which the period t1 to t2 shown in FIG. 8, that is, the purge processing is performed. The processing stage PS4, like the processing stage PS2, is a narrow space, and the wafer 1 runs through the narrow space while being placed on the turntable 201. An inert gas is supplied from the gas supply pipe 210 into the narrow space. After the process stage PS4, the process returns to the process stage PS1, which is the first stage.

  As described above, in the film forming apparatus 200, for example, steps 1 to 4 shown in FIG. With the wafer 1 mounted on the turn table 201, the silicon nitride film is formed on the surface to be processed of the wafer 1 by rotating the wafer 1 up to the set number of times, and in this example, the structure described in the third embodiment. The film can be formed according to the film method.

  The method of forming a silicon nitride film 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.

  When only the film forming method of the silicon nitride film 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 the 1st-3rd embodiment, this invention is not limited to the said 1st-3rd embodiment, It deform | transforms variously in the range which does not deviate from the meaning. It is possible to carry out.

  For example, in the above-mentioned embodiment, although processing conditions were illustrated concretely, processing conditions are not restricted to the above-mentioned concrete illustration. For example, the flow rate of gas can be appropriately adjusted according to the volume of the processing chamber.

  Although the silicon source gas is a DCS gas in the above embodiment, it is not limited to a DCS gas, and a chlorosilane-based gas other than DCS can be used. Furthermore, it is not limited to the chlorosilane-based gas, and it is also possible to use a higher-order chlorosilane-based gas than chlorodisilane. Of course, other than the chlorosilane-based gas, a silane-based gas that does not contain chlorine, or a higher order silane-based gas of disilane or more may be used.

  In addition, the present invention can be variously modified without departing from the scope of the invention.

1: silicon wafer, 2: silicon oxide film, 3: silicon nitride film, 3-1: first silicon nitride layer, 3-2: second silicon nitride layer.

Claims (8)

A method for forming a silicon nitride film, comprising forming a silicon nitride film on a surface to be processed of a target object, comprising:
(1) carrying in the processing object into a processing chamber of a film forming apparatus;
(2) simultaneously supplying a silicon source gas and a nitriding gas 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;
(5) further nitriding the silicon nitride film obtained on the surface to be processed in the processing chamber after the step (3);
Equipped with
Repeat steps (2) to (5) up to the set number of times,
The nitriding gas contains a nitrogen-containing heterocyclic compound gas as a nitriding agent,
In the step (2), another nitriding gas further containing a nitrogen compound gas different from the nitrogen-containing heterocyclic compound gas as a nitriding agent in the treatment chamber of the film forming apparatus in which the object to be treated is accommodated Supply
In the step (5), the other nitride gas is supplied into a processing chamber of the film forming apparatus in which the object to be processed is accommodated. The (5) in step, the other of said nitrogen compound gas contained in the nitriding gas, the process of manufacturing a nitride film according to claim 1, characterized in that it is activated by a plasma. The method for forming a silicon nitride film according to claim 2 , wherein the other nitriding gas contains nitrogen gas instead of the nitrogen compound gas. The (2) step and the (3) step are performed in a state in which the opening degree of a valve connected between the exhaust port of the processing chamber and the exhaust device is narrowed or in a state in which the valve is closed. The method for forming a silicon nitride film according to any one of claims 1 to 3 , wherein The silicon nitride according to any one of claims 1 to 4 , wherein the step (2) and the step (3) are performed in a temperature range of 180 ° C or more and less than 600 ° C. Method of forming a product film. The nitrogen-containing heterocyclic compound gas is
Triazole-based compound Oxatriazole-based compound Tetrazole-based compound Triazine-based compound Tetrazine-based compound Benzotriazole-based compound Benzotriazine-based compound It is selected from a gas containing at least one of benzotetrazine-based compounds. A method of forming a silicon nitride film according to any one of claims 5 to 10. 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 6 , wherein the method is selected from gases containing at least one of the following. A film forming apparatus for forming a silicon nitride film on a surface to be processed of an object to be processed, the film forming apparatus comprising:
A processing chamber for containing 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 housed in the processing chamber;
An exhaust mechanism for exhausting the processing chamber through an exhaust port and an exhaust valve;
The processing gas supply mechanism, the heating device, and a controller for controlling the exhaust mechanism;
The controller controls the processing gas supply mechanism, the heating device, and the exhaust mechanism such that the method for forming a silicon nitride film according to any one of claims 1 to 7 is performed. A film forming apparatus characterized by

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