JP2965188B2 - Film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

(Table of Contents) ・ Industrial application fields ・ Prior art ・ Problems to be solved by the invention (FIG. 8) ・ Means for solving the problems ・ Function ・ Embodiments (1) Embodiments of the present invention MO used in such a film forming method
Configuration of reactive gas supply device and film forming unit of CVD apparatus (FIG. 1) (2) BPSG film forming method according to embodiment of the present invention (FIGS. 2 and 3) (3) Embodiment of the present invention Characteristics of the BPSG film formed by the film forming method (FIGS. 4 to 7)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method, and more particularly to a film forming method for forming a boron-containing insulating film (BSG film, BPSG film) by metal organic chemical vapor deposition (MOCVD). .

[0003]

2. Description of the Related Art With the increase in the density of semiconductor devices, a boron phosphorus glass film (BPSG film: Borophosphosilicate glass) has been developed.
The film is an insulating film useful for flattening a semiconductor substrate. In the case of flattening, the BPSG film is melted and caused to flow, but the melting temperature is preferably as low as possible in order not to limit the temperature of other processes and materials to be used. BP
In order to lower the melting temperature of the SG film, it is sufficient to increase the amount of boron or phosphorus added. However, since the hygroscopicity is increased and boron or phosphorus precipitates, the amount of boron or phosphorus added in an appropriate amount is practically used. Adjusted and used.

Conventionally, a boron-containing insulating film such as a BPSG film or a boron glass film (BSG film:
In the method of forming an orosilicate glass film, TMB (Trimethylboron) is used as a source gas for supplying boron.
ate: B (OCH ₃ ) ₃ ) When using source gas and TEB (Trie
thylborate: B (OC ₂ H ₅ ) ₃ ) A source gas may be used.

In a method using a TMB source gas to form a BPSG film, TEOS (Tetraethylor) is used.
thosilicate: Si (OC ₂ H ₅ ) ₄ ), TMOP (Trimethylphosp
A mixed gas of each source gas of hate: PO (OCH ₃ ) ₃ ) and TMB and an oxygen (O ₂ ) gas containing ozone (O ₃ ) is used as a reaction gas. Hereinafter, the oxygen gas containing ozone is simply referred to as an ozone-containing gas.

[0006] The TEOS source gas is a nitrogen gas containing TEOS, and is produced by bubbling with a nitrogen gas (source carrier gas) having a flow rate of about 3 SLM while the TEOS source is heated to a temperature of 65 ° C. Also, TMO
The P source gas is a nitrogen gas containing TMOP.
With the MOP source heated to a temperature of 60 ° C, the flow rate is approximately 1.
It is made by bubbling with nitrogen gas of 0 to 2.5 SLM.

Further, the TMB source gas is a nitrogen gas containing TMB, and is prepared by bubbling with a flow rate of 0.02 to 0.1 SLM of nitrogen gas while maintaining the TMB source at a temperature of 24 ° C. Here, since the vapor pressure of TMB is high, the flow rate of nitrogen gas containing TMB is made smaller than that of nitrogen gas containing other sources to adjust the amount of boron to be added.

The reaction gas thus produced is guided to the surface of the substrate to be heated and reacted on the surface of the substrate to deposit a BPSG film on the substrate. In a method using a TEB source gas to form a BPSG film, TEOS, TMOP and TOS are used.
A mixed gas of each EB source gas and the ozone-containing gas is used as a reaction gas.

The method of producing the TEOS source gas and the TMOP source gas is the same as described above, except that the TEB source gas is a nitrogen gas containing TEB, and the TEB source is cooled and kept at a temperature of about 10 ° C. , Flow rate about 1.5 SL
It is created by bubbling with M nitrogen gas. The reaction gas thus produced is guided to the heated surface of the substrate to be deposited, and is reacted on the surface of the substrate to deposit a BPSG film on the substrate.

[0010]

However, in the above-described method using a TMB source gas, in order to form an opening in the formed BPSG film, if the BPSG film is etched by wet etching or dry etching, as shown in FIG. There is a problem that overetching occurs in a lower region near the surface of the substrate to be deposited.

Further, in the method using a TEB source gas, since the reactivity of TEB is strong, a large amount of powder is generated in a film forming chamber, which may cause particles,
Uniform supply of boron to the substrate to be deposited is hindered, and BP
This may cause variations in the boron concentration in the SG film. For this reason, it is necessary to frequently clean the film forming chamber, and there is a problem that it takes time to maintain the cleanliness of the CVD apparatus.

The present invention has been made in view of the above-mentioned conventional problems, and provides a method for forming a boron-containing insulating film in which boron is uniformly contained in the formed film and the generation of powder and the like is small. The purpose is to do so.

[0013]

The first object of the present invention is to first pass a carrier gas through a trimethyl borate (TMB) liquid to generate a trimethyl borate (TMB) source gas, and to use the source gas to contain boron. In the film forming method for forming a film on a substrate, the trimethyl borate (T
MB) The liquid temperature of the liquid is set lower than normal temperature, and
By setting the flow rate of the trimethyl borate (TMB) source gas to be at least five times the flow rate at room temperature, the amount of boron supplied when the temperature of the trimethyl borate (TMB) solution is room temperature is substantially reduced. And a second method is to form a film containing boron on a substrate while maintaining the film thickness. Secondly, trimethyl phosphate formed by passing a carrier gas through a trimethyl phosphate (TMOP) liquid (TMOP) source gas, tetraethylorthosilicate (TEOS) source gas generated by passing a carrier gas through a tetraethylorthosilicate (TEOS) liquid, and trimethylborate (T
MB) A trimethyl borate (TMB) source gas generated by passing a carrier gas through a liquid to supply a boron-phosphorus glass film (BPSG film) on a substrate. The liquid temperature of the trimethyl borate (TMB) liquid is set to be lower than the normal temperature, and the flow rate of the trimethyl borate (TMB) source gas is set to be 5 times or more the flow rate at the normal temperature. And a boron-phosphorus glass film (BPSG film) is formed on a substrate while substantially maintaining the amount of boron supplied when the liquid temperature is room temperature. Tetraethyl orthosilicate (TEOS) generated by passing a carrier gas through a tetraethylorthosilicate (TEOS) liquid
Trimethyl borate (T) formed by passing a carrier gas through a source gas and a trimethyl borate (TMB) liquid
MB) source gas and boron glass film (BSG)
Film) on a substrate, wherein the temperature of the trimethyl borate (TMB) liquid is set to a state lower than room temperature, and the flow rate of the trimethyl borate (TMB) source gas is the flow rate at room temperature. Is set to be at least five times the trimethyl borate (TM)
B) The problem is solved by a film forming method characterized in that a boron glass film (BSG film) is formed on a substrate while substantially maintaining the amount of boron supplied when the liquid temperature is normal.

[0014]

According to the investigation by the present inventor, the concentration distribution of boron in the BPSG film formed by the method using the conventional TMB was examined by SIMS, and as shown in FIG. It was found that the boron concentration decreased in a lower region of about 400 ° from the surface of the substrate to be deposited. Therefore,
Since the etching rate is high in such a portion where the boron concentration is low, it is considered that over-etching has occurred in the lower region of the BPSG film.

The following can be considered as a reason for the decrease in the boron concentration. That is, since the flow rate of the carrier gas for bubbling is smaller in the TMB source gas than in the other source gases, even if the flow rate of the carrier gas is slightly changed, the flow rate of the carrier gas becomes smaller.
The supply amount of MB tends to be unstable, and it is difficult to sufficiently spread the inside of the chamber at the initial stage of film formation. For this reason, the amount of boron taken into the BPSG film tends to fluctuate for a certain period from the start of the deposition until the carrier gas flow rate is stabilized, and the formed BPSG film has a lower region of 300 to 500 ° from the surface of the substrate to be deposited. , The boron concentration may decrease.

According to the film forming method of the present invention, the temperature of the trimethyl borate source (TMB source) used when adding boron to the formed film is lowered, and the flow rate of the carrier gas of the TMB source is increased. In particular, in the case of the TMB source, since the vapor pressure is high, the TMB source temperature is set to 0.
It is necessary to sufficiently lower the vapor pressure as an appropriate temperature of not more than 0 ° C. and sufficiently increase the flow rate of the carrier gas, that is, to 0.5 SLM or more. In this case, when the flow rate of the carrier gas is set so as to satisfy the above condition, it is possible to adjust the temperature of the TMB source and adjust the vapor pressure of TMB so as to obtain a necessary boron concentration in the formed film. it can. Thus, the flow rate of the carrier gas can be increased while maintaining the amount of boron added to the film to be formed.

Further, the flow rate of the TMB carrier gas is set to TE.
By making the flow rate of the TMB carrier gas close to the flow rate of the film forming gas such as the OS or the other carrier gas such as TMOP, for example, by setting the flow rate of the TMB carrier gas to 1/3 or more of the flow rate of the film forming gas, the carrier gas containing boron is formed. The film gas can be distributed almost simultaneously and in the same place in the film forming chamber. As described above, the instability of the supply of boron is eliminated, and the amount of boron taken into the formed film does not fluctuate much with the fluctuation of the flow rate of the carrier gas. Can be prevented.

Further, since the TMB source gas is used, there is an advantage that powder is not generated as much as in the case of the TEB source gas. For this reason, the cleaning of the film forming unit is also performed by TE.
Even if it is not performed as frequently as in the case of B, it is possible to suppress the variation in the boron concentration and the generation of particles.
Therefore, the throughput of the device is improved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. (1) MO used in the film forming method according to the embodiment of the present invention
Description of the configuration of the reactive gas supply device and the film forming unit of the CVD device FIG. 1 is a configuration diagram of the reactive gas supply device of the MOCVD device. In the figure, reference numeral 2a denotes a reaction gas
Oxygen gas containing ozone (ozone containing gas) and nitrogen gas containing TEOS source (TEOS
Source gas), nitrogen gas containing TMOP source (TMO)
P source gas) and nitrogen gas (TM
B source gas) flowing through gas pipes 2b, 2c, 2e, 2g
Are connected to each other, and a gas pipe 2i connected to the gas dispersion tool 26 is connected.

The gas pipe 2b flows the ozone-containing gas formed by the ozone generator 3. Gas pipe 2c is TEO
Flow the S source gas. The gas pipe 2e allows a TMOP source gas to flow. The gas pipe 2g flows the TMB source gas. Each gas pipe 2b, 2c, 2e, 2g has a flow /
Valves 5a to 5c, 5e and 5g for adjusting the stop are provided.

Reference numerals 2d, 2f and 2h denote nitrogen gas (carrier gas) as a source carrier gas, respectively.
A gas pipe for sending to the containers 7a to 7c containing the EOS source, the TMOP source, and the TMB source is immersed in the TEOS source, the TMOP source, and the TMB source, and TEOS, TMOP, and TM are bubbled with nitrogen gas.
A source gas containing B is formed. Further, valves 5d, 5f, 5h for adjusting flow / stop are provided in the respective gas pipes 2d, 2f, 2h.

Further, reference numeral 2i denotes a gas pipe branched from the gas pipe 2a and connected to the gas distributor 26, and is provided with a valve 5i for adjusting flow / stop. Reference numeral 3 denotes an ozone generator connected to the gas pipe 2b, and 4a to 4c.
Are TEOS source, TMOP source and TMB respectively
A container for storing the sauce, which is sealed. 7a, 7b
Is provided at the periphery of the TEOS container 4a and the TMOP container 4b, respectively, and is a heater for heating and keeping the temperature of the TEOS source and the TMOP source, and 8 is provided at the periphery of the TMB container 4c to cool the TMB source and keep the temperature. Bowl, 6
Reference numerals a to 6d denote mass flow controllers for adjusting the flow rates of oxygen gas sent to the ozone generator 3 and nitrogen gas as carrier gas.

Reference numeral 9 denotes a carrier gas which is provided at the most upstream of the pipe 2a and which introduces a carrier gas for introducing a reaction gas, which is a mixture of an ozone-containing gas, a TEOS source gas, a TMOP source gas and a TMB source gas, to the gas dispersing device 26. At the inlet, a large flow rate, for example, 18 SLM of nitrogen gas is flowed. When forming a BSG film (boron glass film), use TM
B source gas is used, and when a BPSG film (boron phosphorus glass film) is further formed, a TMOP source gas and T
Both MB source gases are used. When forming a PSG film (phosphorus glass film), a TMOP source gas is used.

The gas pipes 2a, 2c, 2e, 2g,
2i is usually maintained at a temperature equal to or higher than the source temperature by a heater (not shown) so that the flowing source gas does not liquefy and adhere to the inner walls of the gas pipes 2a, 2c, 2e, 2g, 2i. The above constitutes the reaction gas supply device. The reaction gas supplied from the above reaction gas supply device is sent to the film forming unit.

Next, the film forming section will be described. In FIG.
Reference numeral 21 denotes a chamber, and 22 denotes an exhaust port for exhausting used gas and unnecessary gas from inside the chamber 21.
To the outside of the chamber 21. Reference numeral 24 denotes a wafer holder for mounting and fixing the wafer on the wafer mounting surface by a vacuum chuck or the like, and 25 is provided separately from the wafer holder 24 and indirectly heats the wafer 27 via the wafer holder 24. The heater 26 is a gas dispersing device which is provided so as to face the wafer mounting surface of the wafer holder 24 and emits a reactive gas to the surface of the wafer 27 on the wafer mounting surface. (2) Description of Film Forming Method According to Example of the Present Invention (A) Description of Relationship between Boron Concentration and Phosphorus Concentration in BPSG Film When Film Forming Conditions are Changed FIG. FIG. 4 is a characteristic diagram showing a relationship between a temperature of each source used in the method and a vapor pressure of a corresponding source gas. The vertical axis shows the vapor pressure (mmHg) of each source gas on a logarithmic scale, and the horizontal axis shows the source temperature (° C.) on a proportional scale. For comparison, TEB
Are also shown.

As shown in the figure, it can be seen that the vapor pressure of TMB is considerably higher than other sources. In this case, the source temperature is set to an appropriate temperature lower than the normal temperature and the vapor pressure is reduced, so that the supply amount of boron is maintained at a constant amount.
The flow rate of the carrier gas can be increased. Thus, the instability of the supply of boron is eliminated, and the boron can be sufficiently diffused into the chamber at an early stage of film formation. Therefore, it is possible to suppress a change in the amount of boron taken into the BPSG film with respect to a change in the flow rate of the carrier gas, and to prevent a decrease in the initial concentration. In particular, from the investigation results, the flow rate of the TMB source gas is preferably at least five times the flow rate at normal temperature. The amount of boron added to the BPSG film can be adjusted by adjusting the source temperature and the flow rate.

FIG. 3 shows the flow rate of TMB source gas and TM
FIG. 4 is a characteristic diagram showing a relationship between a phosphorus concentration and a boron concentration in a BPSG film when the flow rate of an OP source gas is changed.
The vertical axis represents the phosphorus concentration (wt%) shown on a proportional scale, and the horizontal axis represents the boron concentration (wt%) shown on a proportional scale. Hereinafter, the film forming conditions will be described. The investigation range is shown for the flow rate of the TMB source gas and the flow rate of the TMOP source gas.

TEOS source gas flow rate: 3 SLM TEOS source temperature: 65 ° C. TOP source gas flow rate: 1.0 to 2.5 SLM TOP source temperature: 60 ° C. TMB source gas flow rate: 0.5 to 2.0 SLM TMB source temperature: -23 ° C. Ozone-containing gas flow rate : 7.5 SLM (O ₃ concentration = 4%) Carrier gas: Nitrogen gas Carrier gas flow rate: 18 SLM Depot temperature: 400 ° C Film thickness: 5000Å According to FIG. 3, the TMB source gas is kept at a constant flow rate of the TOP source gas. Increasing the flow rate increases the concentration of boron and the concentration of boron. On the other hand, when the flow rate of the TMOP source gas is increased while the flow rate of the TMB source gas is kept constant, the phosphorus concentration increases, but the boron concentration may decrease or increase, and the whole does not change much. In the above range of the flow rate of the TMB source gas and the flow rate of the TOP source gas, the phosphorus concentration is set to 2.5 to 7.2 wt%.
, The boron concentration can be adjusted in the range of 2.4 to 5.5 wt%.

Note that the above ranges of the phosphorus concentration and the boron concentration are merely examples, and the present invention can be applied to other than the above source temperature conditions. In that case, based on the necessary boron addition amount in the formed film, TMB
It is necessary to adjust the source temperature so that the source gas flow rate satisfies the above conditions. As described above, by appropriately adjusting the above-described film forming conditions, it is possible to keep the phosphorus concentration and the boron concentration within predetermined ranges and minimize the variation in the concentration.

(B) Description of Film Forming Method Next, a method of forming a BPSG film on the wafer 27 in the film forming section using the reaction gas supply device shown in FIG.
This will be described with reference to FIG. First, in the reaction gas supply device as shown in FIG.
The S source and the TMOP source are heated, and the source temperatures are maintained at 65 ° C. and 60 ° C., respectively. Further, the TMB source is cooled by the cooler 8 and maintained at a temperature of -23 to -27C.

In such a state, the wafer 27 is brought into contact with the wafer mounting surface of the wafer holder 24, and the wafer 27 is fixed to the wafer mounting surface by the vacuum chuck. At this time, electric power is supplied to the heater 25 and the wafer holder 24 is supplied.
Is maintained at about 400 ° C. Next, after the temperature of the wafer 27 reaches about 400 ° C., the valve 5b of the reaction gas supply device is opened and oxygen gas having a flow rate of 7.5 SLM is introduced into the ozone generator 3 to supply an ozone-containing gas having an ozone concentration of 4%. At the same time, the ozone-containing gas is sent to the gas pipe 2a by opening the valve 5a.

Open the valve 5d and set the flow rate to about 3 SLM.
Is sent to the TEOS container 4a for bubbling, and the valve 5c is opened to send nitrogen gas containing TEOS to the gas pipe 2a. Further, by opening the valve 5f, nitrogen gas at a flow rate of about 1.3 SLM is sent to the TMOP container 4b, and bubbling is performed.
The nitrogen gas containing MOP is sent to the gas pipe 2a.

Open the valve 5h and set the flow rate to about 1.3 SL.
M nitrogen gas is fed into the TMB container 4c for bubbling, and the valve 5g is opened to send nitrogen gas containing TMB to the gas pipe 2a. Thereby, a mixed gas of TEOS, TMOP, TMB and an ozone-containing gas as a reaction gas flows through the gas pipes 2a and 2i, and
6 and released onto the wafer 27. At this time, since the gas pipes 2c, 2a, 2i, etc. are maintained at a temperature of 65 ° C. or higher, which is higher than the temperature of the source heating, the vapor pressure of the flowing reaction gas is set in the gas pipes 2c, 2a, 2i, etc. The pressure becomes equal to or lower than the saturated vapor pressure, and liquefaction does not occur on the inner walls of the gas pipes 2c, 2a, 2i and the like. Therefore, the composition of the reaction gas does not fluctuate.

By maintaining this state for a predetermined time, a BPSG film having a predetermined thickness is formed on the wafer 27. At this time, by cooling the TMB source, the TM
Since the vapor pressure of B is lowered and the flow rate of the TMB source gas is increased, it is possible to suppress the initial fluctuation of the supply amount of boron and to suppress the fluctuation of the supply amount of boron with respect to the fluctuation of the flow rate of the source carrier gas. Therefore, boron is uniformly added to the BPSG film.

A desired impurity concentration can be obtained by appropriately adjusting the source temperature and the flow rate. According to the investigation, the phosphorus concentration in the formed BPSG film was 4.0 to 4.1 wt.
%, And the boron concentration was 3.4 to 3.7 wt%. Further, since the TMB source was used, the generation of powder in the chamber was significantly reduced as compared with the case where the TEB source was used. Therefore, it is no longer necessary to clean the chamber more frequently than in the case where a TEB source is used, in order to suppress variations in boron concentration. (3) Description of Characteristics of BPSG Film Formed by the Above-described Film Forming Method (A) Description of Investigation Results of Boron Concentration Distribution in BPSG Film FIG.
The results obtained by the SIMS method will be described. The vertical axis is B
Detected intensity of each particle of Si, P and B in PSG film (cp
s), and the horizontal axis represents the depth (n) from the surface of the BPSG film.
m). For comparison, FIG. 4B shows the conventional T
The results of a similar investigation on a BPSG film formed by a film forming method using MB will be described.

The sample used for the investigation was prepared by the above-mentioned film forming method, and the thickness of the BPSG film formed on the underlying substrate made of silicon is about 200 nm. 4B, the thickness of the BPSG film is about 270 nm. According to the result, FIG.
As shown in (a), there is no large change in both the phosphorus concentration and the boron concentration in the BPSG film near the base substrate, indicating that a uniform concentration distribution is obtained. On the other hand, in the conventional case, as shown in FIG.
It can be seen that the boron concentration distribution in the G film sharply decreases from about 380 ° from the interface to the interface.

As described above, the boron concentration distribution in the BPSG film does not vary greatly and a uniform boron concentration distribution can be obtained over the entire film, so that abnormal etching caused by a decrease in the boron concentration as in the conventional example can be prevented. can do. (B) Description of Investigation of Uniformity of Boron Concentration Distribution in BPSG Film FIG. 5 shows the result of an investigation on the variation in the boron concentration in the BPSG film within the wafer surface. The vertical axis represents the variation of the boron concentration and is represented by the following equation. ΔN = 1/2 × (Nmax−Nmin) / Nave where Nmax is the maximum value of the boron concentration distribution in the wafer surface Nmin: the minimum value of the boron concentration distribution in the wafer surface Nave is the wafer surface of the boron concentration distribution The horizontal axis represents the number of processed wafers.

For the purpose of comparison, a similar investigation was conducted for a case where a BPSG film was formed by a method using a TEB source gas. Further, in the case of the embodiment of the present invention, the inside of the chamber is not cleaned within the investigation range of 300 sheets, but in the case of using the TEB source gas, the inside of the chamber is cleaned every 100 sheets. I have.

The samples of the examples were prepared by the film forming method and conditions described in the above (2) (B). However, the film formation time is set longer than that of the example, and the film thickness is set to 5000 °. On the other hand, conditions for the method using TEB are shown below. TEOS source gas flow rate: 3 SLM TEOS source temperature: 65 ° C. TOP source gas flow rate: 1.5 SLM TOP source temperature: 60 ° C. TEB source gas flow rate: 1.5 SLM TEB source temperature: 10 ° C. O ₃ / O ₂ flow rate: 7.5 SLM (O ₃ (Concentration = 4%) Deposition temperature: 400 ° C. The characteristics of the BPSG film formed by the method using TEB are shown below.

Film thickness: 5000 ° C. Phosphorus concentration: 4.0 to 4.3 wt% Boron concentration: 3.4 to 3.7 wt% According to the results, in the case of the embodiment of the present invention, the number of processed sheets is 300.
Although the inside of the chamber was not cleaned within the inspection range of one sheet, the variation of the boron concentration was within ± 3%. On the other hand, in the case of the method using the TEB source gas, the variation in the boron concentration exceeded ± 3% every time the number of processed sheets reached almost 100. This is because the powder adheres to the inner wall of the chamber and becomes a source of excess boron,
It is considered that this affected the variation of the boron concentration in the PSG film.

Therefore, when the inside of the chamber is cleaned when the variation of the boron concentration exceeds ± 3%, and when the TMB source gas of the embodiment is used, the number of processed wafers is 300 (accumulated film thickness is about Cleaning may be performed in the above cycle.
When an EB source gas is used, it is necessary to perform cleaning every approximately 100 substrates (corresponding to an accumulated deposited film thickness of 30 to 50 μm). For this reason, the maintainability of the device is improved.

(C) Description of Investigation of Boron Content and Phosphorus Content in Powder in Exhaust Pipe FIG. 6 is a characteristic diagram showing results of investigation of boron content and phosphorus content in powder deposited in the chamber and in the exhaust pipe. It is. The vertical axis is the amount of boron and phosphorus in the powder (wt%)
And the horizontal axis represents the distance from the wafer. This is a guide for determining whether the amount of boron and the amount of phosphorus are effectively incorporated into the BPSG film.

FIG. 7 is a characteristic diagram obtained by rewriting the ratio of the amount of boron to the amount of phosphorus in FIG. The vertical axis represents the ratio of the amount of boron to the amount of phosphorus in the powder, and the horizontal axis represents the distance from the wafer. This is a guide for determining whether the amount of boron and the amount of phosphorus are effectively incorporated into the BPSG film. The distance from the wafer is about 17c
m or less indicates the powder collected in the chamber, and about 17 cm or more indicates the powder collected in the pipe.

For comparison, the results of the investigation using the method using TEB are also shown in FIGS. In the case of using the method using TMB, the film forming method and conditions of the above-described embodiment (2) (B) are used, and in the case of using the method using TEB, the film forming conditions shown in the above (3) (B) are used. Was used.

According to the results shown in FIG. 6, the residual boron concentration in the powder is higher when the TEB source gas is used than when the TMB source gas is used. In particular, the residual boron concentration is very high in the chamber 13 cm from the center and in the exhaust pipe 30 cm from the center. This indicates that boron in the reaction gas is exhausted without being effectively consumed. Therefore, it can be said that the method using the TMB source gas has higher reaction efficiency.

According to the results of FIG. 7, when the TMB source gas is used, the B
The amounts of phosphorus and boron taken into the PSG film are close to one. This indicates that the amount of phosphorus and the amount of boron are taken in evenly by the BPSG film in a state where the flow rates of the TMB source gas and the TMOP source gas are matched, which is a factor for reducing the variation of the boron concentration.

As described above, according to the method for forming a boron-containing insulating film according to the embodiment of the present invention, TM is used as the boron source.
The B source is used, and the source temperature is maintained at an appropriate temperature lower than the normal temperature to increase the flow rate of the source gas and match the flow rates of other source gases. Further, since the TMB source is used, the generation of powder is small, and the chamber is hardly contaminated.

As described above, variations in the boron concentration in the boron-containing insulating film can be suppressed, and abnormal etching during selective etching can be prevented. Further, since the generation of powder is small, the number of times of cleaning can be reduced as compared with the case where a TEB source gas is used. Thereby, the maintainability of the device can be improved.

In the above embodiment, the present invention is applied to the BPSG film as the boron-containing insulating film.
The present invention can be applied to a film. Further, the present invention is applied to the TMB source, but can be applied to other sources.

[0050]

As described above, according to the film forming method of the present invention, the source temperature is reduced and the flow rate of the source carrier gas is increased to suppress the variation in the impurity content in the film formed. . Further, since the TMB source is used as the boron source, the generation of powder is small and the chamber is not easily contaminated. Therefore, variation in the boron concentration in the boron-containing insulating film can be suppressed.

Thus, abnormal etching during selective etching of the boron-containing insulating film can be prevented.
Further, since the generation of powder is small, the number of times of cleaning for maintaining the cleanliness of the apparatus can be reduced. Thereby, the maintainability of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of a reactive gas supply device and a film forming unit of an MOCVD apparatus according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a source gas vapor pressure and a source temperature used in a film forming method according to an embodiment of the present invention.

FIG. 3 shows a BPS obtained by changing a TMB source gas flow rate and a TMOP source gas flow rate according to an embodiment of the present invention.
FIG. 4 is a characteristic diagram showing a relationship between a boron concentration and a phosphorus concentration in a G film.

FIG. 4 is a characteristic diagram showing a boron concentration distribution in a BPSG film formed by a film forming method according to an example of the present invention.

FIG. 5 is a characteristic diagram showing the dependence of the variation (ΔN) in the boron concentration in the BPSG film formed by the film forming method according to the embodiment of the present invention on the number of processed substrates.

FIG. 6 is a characteristic diagram showing the measurement position dependence of the amount of boron remaining in the powder remaining in the MOCVD apparatus according to the embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a measurement position dependency of a ratio of a residual amount of boron / a residual amount of phosphorus in powder remaining in the MOCVD apparatus according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a problem of a film forming method according to a conventional example.

[Explanation of symbols]

 2a to 2i gas pipe, 3 ozone generator, 4a to 4c container, 5a to 5i valve, 6a to 6d mass flow controller, 7a, 7b, 25 heater, 8 cooler, 9 carrier gas inlet, 21 chamber, 22 exhaust port , 23 exhaust pipe, 24 wafer holder, 26 gas disperser, 27 wafer.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-357837 (JP, A) JP-A-4-372131 (JP, A) Journal of Electric Materials Vol. 19 No. 1 1990 p. 45-49J. Electrochem, Soc, Vol. 140 No. 10 Octo ber 1993 p. 2922−2926

Claims (3)

(57) [Claims] 1. A film forming method in which a carrier gas is passed through a trimethyl borate (TMB) liquid to generate a trimethyl borate (TMB) source gas, and a film containing boron is formed on the substrate using the source gas. By setting the liquid temperature of the trimethyl borate (TMB) liquid to a state lower than normal temperature and setting the flow rate of the trimethyl borate (TMB) source gas to be 5 times or more the flow rate at normal temperature, Forming a film containing boron on a substrate while substantially maintaining the amount of boron supplied when the temperature of the trimethyl borate (TMB) solution is room temperature. 2. A trimethyl phosphate (TMOP) source gas generated by passing a carrier gas through a trimethyl phosphate (TMOP) liquid and a tetraethyl orthosilicate generated by passing a carrier gas through a tetraethyl orthosilicate (TEOS) liquid (TEOS) source gas and trimethyl borate (TM) generated by passing a carrier gas through a trimethyl borate (TMB) liquid
B) Supplying a source gas and boron-phosphorus glass film (BP)
An SG film) on a substrate, wherein the temperature of the trimethyl borate (TMB) liquid is set to a state lower than room temperature, and the flow rate of the trimethyl borate (TMB) source gas is room temperature. By setting the flow rate to be 5 times or more, the boron-phosphorus glass film (BPSG film) while substantially maintaining the amount of boron supplied when the temperature of the trimethyl borate (TMB) solution is normal temperature. Forming a film on a substrate. 3. Tetraethyl orthosilicate (TEO)
S) A tetraethylorthosilicate (TEOS) source gas generated by passing a carrier gas through a liquid and a trimethylborate (TMB) source gas generated by passing a carrier gas through a trimethylborate (TMB) solution are supplied to form boron. In a film forming method for forming a glass film (BSG film) on a substrate, the liquid temperature of the trimethyl borate (TMB) solution is set to a state lower than room temperature, and the flow rate of the trimethyl borate (TMB) source gas is reduced. By setting the flow rate to be at least five times the flow rate at normal temperature, the boron glass film (BS) is maintained while the amount of boron supplied when the temperature of the trimethyl borate (TMB) liquid is normal temperature is substantially maintained.
(G film) on a substrate.