JP3254294B2 - Film forming method and film forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a method a semiconductor film formation, a semiconductor film forming method, in particular for forming a TEOS-O ₃ oxide film on the semiconductor surface.

[0002]

2. Description of the Related Art In recent years, ultra-high integration of semiconductor devices has
The circuit structure has been developed three-dimensionally, and the degree of integration per unit area has been increased. Particularly recently, as shown in FIG. 1 and FIG.
It is required to stack a plurality of layers of ultrafine circuits that are wired in a pattern with an interval of 5 μm, and for that purpose, it is necessary to establish a highly accurate interlayer insulating film technology.

As an interlayer insulating film, as shown in FIG. 1, a plasma-tetraethylorthosilicate (P-TEOS) film having excellent insulating properties is first formed, and an SOG film is formed thereon to secure flatness. (Spin-on-Glass) is applied, and a P-TEOS film is again formed thereon for SOG encapsulation. However, since SOG has many OH groups, the film quality is poor,
This has caused oxidation and corrosion of the aluminum base, cracks and stress migration. Also,
It also reduced the hot carrier resistance.

For this reason, recently, as shown in FIG.
Using TEOS and ozone (O ₃ ) instead of OG,
TEOS-O ₃ with little influence of H group and excellent flatness
Attention has been paid to a multilayer insulating film structure in which an oxide film layer is sandwiched between P-TEOS films. Here, in order to form TEOS-O ₃ , a normal pressure CVD method or a quasi-normal pressure CVD method in which a process is performed in a pressure atmosphere of about several hundred Torr has been conventionally used.

[0005] However, in the processing pressure atmosphere used in the conventional method, particles are easily generated, and the TEOS-containing gas and the O ₃ -containing gas react in the gas phase to form volatile substances in the gas phase. scattered consumed, resulting in contributing gas amount to the film formation is reduced, there is a problem that the deposition rate of TEOS-O ₃ oxide film becomes slow.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and a first object of the present invention is to adjust the processing conditions so that the TEOS content is reduced. Provided is a new and improved semiconductor film formation method capable of suppressing a reaction between a gas and an O ₃ -containing gas in a gas phase, preventing generation of particles, improving a deposition rate, and forming a high-quality film. It is to be.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems
According to a first aspect of the present invention, a processing chamber capable of evacuating is provided.
And a mounting member disposed in the processing chamber and capable of mounting an object to be processed.
A stage and a heating device for heating the object to be processed.
A film apparatus, wherein a first gas is introduced to an upper surface of the processing chamber.
And a processing gas introduction path is provided for the processing chamber.
A plurality of processing gas guides for introducing the second gas are provided on the side wall.
Provided is a film forming apparatus characterized by having an entrance.
Is done. According to another aspect of the present invention, a vacuum pump is provided.
Introduces processing gas into a functional processing chamber and places it in the processing chamber.
A film forming method for forming a film on the surface of the processed object,
The processing chamber is evacuated to a vacuum atmosphere of less than 20 Torr.
Containing an organic silicon source from the upper surface of the processing chamber.
While introducing the first gas,
The reaction with the organic silicon source of the first gas from a plurality of locations
Introducing a second processing gas containing the corresponding component and heating
Maintained at a temperature between 300 ℃ and 500 ℃ by the device
Film forming method, wherein a film is formed on the surface of an object to be processed.
Is provided.

According to the present invention, as the first gas,
TEOS (tetraethylorthosilicate), TMOS
(Tetramethyl orthosilicate), OMCTS (octamethylcyclotetrasiloxane) and TMCTS
It is possible to use any one component-containing gas selected from the group consisting of (tetramethylcyclotetrasiloxane). Further, as the second gas, any one of the component-containing gases selected from the group consisting of ozone (O ₃ ) and active oxygen (O ^{− *} ) can be used. Further, the present invention provides a method for manufacturing the first gas,
Using OS-containing gas, and using the O ₃ containing gas as the second gas, in the case of forming a TEOS-O ₃ oxide film as the reaction film, in particular, it can be obtained excellent effects.

In carrying out the above method,
It is preferable that the first gas and the second gas are mixed near the surface of the object. Regarding the film formation temperature, when the film formation temperature is less than 500 ° C. and 300 ° C. or more, more excellent effects can be obtained. Further, regarding the amount of the TEOS-containing gas in the first gas,
The second gas is preferably set to 400 sccm or less, and the amount of the O ₃ -containing gas in the second gas is preferably set to 4000 sccm or less.

[0010]

According to the present invention constructed as described above, since the treatment is performed in a pressure atmosphere much lower than in the conventional method, the influence of the radiant heat from the substrate is reduced by the TEOS-containing gas and the O ₃ -containing gas. Therefore, it is possible to minimize the amount of the gas consumed by reacting in the gas phase before reaching the substrate surface. As a result, the TEOS-O ₃
The deposition rate of the oxide film is improved. Further, by mixing the TEOS-containing gas and the O ₃ -containing gas at a position as close as possible to the surface of the object to be processed, it is possible to further reduce the amount of gas that is reacted and consumed in the gas phase.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a semiconductor film forming method according to the present invention will be described below with reference to the accompanying drawings. First, an embodiment of an apparatus for performing the method of the present invention will be described with reference to FIG. The illustrated cold-wall type single-wafer CVD apparatus 1 includes a processing chamber 2 configured in an airtight manner.
The processing chamber 2 is provided with a mounting table 3 on which a semiconductor wafer W to be processed can be mounted and fixed.
An appropriate heating device 4 is mounted on the mounting table 3,
The semiconductor wafer W mounted and fixed on the upper surface can be heated to a desired film forming temperature, for example, 400 ° C.

A first processing gas introduction pipe 5 is attached to the upper surface of the processing chamber 2, and the pipe 5 is vaporized by bubbling nitrogen gas in a first gas source (not shown) from the pipe 5. A first processing gas, for example, a gas containing TEOS (tetraethylorthosilicate (Si (OC ₂ H ₅ ) ₄ )), which has been vaporized, is introduced into the processing chamber 2 through a vaporizer (not shown). The TEOS-containing gas introduced from the conduit 5 is configured to diffuse uniformly on the surface of the semiconductor wafer via the showerhead 6.

Further, a plurality of second
The processing gas introduction pipe 7 is attached so that the O ₃ -containing gas is uniformly diffused from the second gas source (not shown) onto the surface of the semiconductor wafer. As in the embodiment shown in FIG. 3, a TEOS-containing gas is introduced from above the processing chamber 2 and an O ₃ -containing gas is introduced from the side of the processing chamber 2 so that two processing gases can be applied to the semiconductor wafer. It becomes possible to mix at a position as close as possible to the surface. As a result, as described later, it is possible to prevent the two processing gases from reacting in the gas phase and being consumed, thereby reducing the amount reaching the surface of the processing object.

Further, an exhaust pipe 9 is arranged around the mounting table 3 via a suitable valve 8, and the exhaust pipe 9 is connected to exhaust means (not shown), for example, a vacuum pump. The processing chamber 2 can be evacuated to a desired pressure, for example, 6 Torr by opening and closing the valve 8.

Here, in the prior art, TEOS-
The inside of the processing chamber was maintained at normal pressure in order to form an O ₃ oxide film. In addition, even when the low pressure CVD process is performed, the pressure atmosphere is adjusted to at most 20 Torr or more. As described above, conventionally, it is considered that the TEOS-O ₃ oxide film cannot be formed at a high speed in a pressure atmosphere of less than 20 Torr, and the film formation process is performed in a normal pressure or a quasi-normal pressure atmosphere.

However, according to the embodiment of the film forming method according to the present invention, as described later, less than 20 Torr, preferably 10 Torr or less, more preferably 6 Torr or less.
It has been clarified that a preferable deposition rate of the TEOS-O ₃ oxide film can be obtained by adjusting the processing chamber 2 to a reduced pressure atmosphere of r or less. In addition, the film quality of the formed TEOS-O ₃ oxide film can be sufficiently satisfied.

The excellent effects of the embodiment of the present invention will be described with reference to FIG. FIG. 4 shows 4 sccm TEOS gas and 50 s for a 15 mm × 15 mm sample wafer using the apparatus shown in FIG. 3 for the experiment.
4 is a graph showing a relationship between a substrate temperature and a deposition rate when a TEOS-O ₃ oxide film is formed with ccm O ₃ gas. In the experiment, the pressure in the processing chamber was set to 100 Torr, 53
The substrate temperature was set to 175 ° C., 225 ° C., and 2 Torr under each pressure atmosphere.
The measurement was performed by measuring the respective deposition rates when the temperature was adjusted to 75 ° C., 325 ° C., and 400 ° C.

As a result of the experiment, as shown in the figure, when the substrate temperature is relatively low, that is, when the substrate temperature is less than about 300 ° C., as has been conventionally observed, the higher the processing pressure, the higher the deposition rate. Has become. However, when the substrate temperature exceeds about 300 ° C., 100 Torr and 53
In the case of Torr, a result was obtained in which the deposition rate sharply decreased as the substrate temperature increased. On the other hand, when the pressure is set to 6 Torr as in the embodiment of the present invention, the deposition rate hardly decreases even when the substrate temperature increases. As a result, in a region where the substrate temperature is about 300 ° C. or more, the deposition rate is reversed,
The most favorable deposition rate was obtained when the pressure was lower than when the pressure was high, that is, when the pressure was 6 Torr.

Here, TEOS formed in an environment with a low substrate temperature shows a higher deposition rate when the processing pressure is higher.
As will be described later, the film quality of the —O ₃ oxide film is so poor that it cannot be actually used. Therefore, from the above results, when the substrate temperature is set to 300 ° C. or higher in order to obtain a TEOS-O ₃ oxide film having a film quality that can be used, the pressure atmosphere in the processing chamber is reduced as in the method according to the present invention. 2
It has been found that the most preferable deposition rate can be obtained by adjusting the pressure to less than 0 Torr, preferably 10 Torr or less, more preferably 6 Torr or less.

Next, the reason why the above-described excellent effects are obtained by one embodiment of the method of the present invention will be described with reference to FIG. In this figure, the pressure dependence of component analysis in the gas phase was examined using FTIR (Fourier infrared spectroscopy). The vertical axis represents the infrared absorption intensity of each component in the mixed gas when ozone is supplied for normalization,
It was expressed as a ratio to the absorption intensity of Si—O in TEOS molecules when ozone was not supplied at each pressure. The horizontal axis is the substrate temperature. Also, the left half in the figure represents the components in the source gas, and the Si in the TEOS molecule is seen from above.
-O, CH ₃ and ozone in TEOS molecules. The right half shows by-products of the reaction, from the top CO ₂ , _-
C = O, an H ₂ O.

From this figure, it can be seen that as the substrate temperature increases, the absorption intensity on the source gas side decreases, while on the other hand, by-products increase. When the gas pressure increases, the absorption intensity on the source gas side decreases, while the amount of by-products increases. Considering the results of these two points and the decrease in deposition rate under high temperature conditions (300 ° C. or higher) and high pressure conditions, the following is presumed. When the temperature of the substrate becomes high, thermal energy (radiation or convection) from the substrate causes the reaction between the processing gases to occur in the gas phase before reaching the surface of the substrate, consuming that amount. Since frequent collisions occur, the reaction is further promoted and gas is consumed. As a result, the amount of the source gas that can reach the substrate is reduced, so that the higher the pressure, the lower the deposition rate.

However, as can be easily understood from FIG. 5, the consumption amount of TEOS and O ₃ in the processing gas or the increase amount of the reaction by-product generated in the processing chamber is reduced by 20 Torr in the processing chamber according to the present invention. Less than 10To
When the temperature is set to rr or less, more preferably 6 Torr, there is not much change even when the substrate temperature is high. That is, in such a low pressure atmosphere, since the degree of vacuum is high, the processing gas is hardly affected by the heat energy from the heated substrate. Therefore, even when the temperature is increased, the processing gas is consumed in the gas phase. Instead, it reaches the surface of the object to be processed, and as a result, a high deposition rate can be maintained.

By the way, there is a method in which the film quality is simply immersed in a diluted hydrofluoric acid solution after film formation, and the film quality is easily evaluated by comparing the etching rate with the thermal oxide film based on the highest quality thermal oxide film. At a low temperature of 300 ° C. or lower, the film quality is poor (10 times or more the etching rate of the thermal oxide film), and is not practical.
As shown in FIG. 6, the film quality at 300 ° C. or higher is improved to about six times the etching rate of the thermal oxide film in any pressure range. Therefore, as described above, it has been found that a process at a reduced pressure of less than 20 Torr, preferably a process at 6 Torr or less is effective, in combination with the fact that the deposition rate does not decrease as the pressure decreases.

The embodiment of the method of the present invention has been made in view of such a fact, and has a processing chamber of less than 20 Torr,
Preferably 10 Torr or less, more preferably 6 To
rr or less, and in the processing chamber, TE
An OS-containing gas and an O ₃ -containing gas are flowed, and a TEOS-O ₃ oxide film is formed on the surface of the object placed in the processing chamber and maintained at a film formation temperature of, for example, 400 ° C. Since the processing is performed in such a low pressure atmosphere, the processing gas is hardly affected by the thermal energy from the substrate, and as a result, a high deposition rate can be maintained even when the substrate temperature is high.

Further, according to an embodiment of the present invention, the TEO
By mixing the S-containing gas and the O ₃ -containing gas as close as possible to the surface of the object to be processed, it is possible to further reduce the consumption of the processing gas and further slow down the deposition rate.

Although the embodiment in which the method of the present invention is applied to the cold wall type single-wafer CVD apparatus shown in FIG. 3 has been described above, the embodiment of the method of the present invention is not limited to the above-described apparatus. Next, an example in which the present invention is applied to a hot wall type single wafer type CVD will be described with reference to FIG. In the apparatus shown in FIG. 7, components having the same functions as those of the apparatus shown in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

In the cold-wall type single-wafer CVD apparatus as shown in FIG. 3, since the TEOS-containing gas source shows a liquid phase at room temperature, it is vaporized by bubbling of nitrogen gas or vaporization of a vaporizer. Introduced indoors,
The film was being formed. However, in a cold-wall single-wafer CVD apparatus, since the inner wall of the processing chamber is maintained at room temperature, when the processing gas introduced into the processing chamber comes into contact with the inner wall of the processing chamber, the gas aggregates and liquid particles are formed. In some cases. As a result, the liquid particles cause the generation of particles in the processing chamber, or the deterioration of the film quality or the contamination in the processing chamber.

In order to solve such a problem, a heating means 10 is provided on the side wall of the processing chamber 2 as shown in FIG. 7, and the side wall of the processing chamber 2 is heated together with the mounting table 3 to reduce the temperature of the side wall. Hot wall type single wafer type CV which can be maintained at a temperature at which the TEOS-containing gas does not agglomerate, for example, 50 ° C.
It is preferable to configure it as a D device. With this configuration, it is possible to avoid the occurrence of gas aggregation.

In the apparatus shown in FIG. 3, a TEOS-containing gas is introduced from a first gas introduction pipe line 5 provided at an upper portion of the processing chamber, and an O ₃ -containing gas is provided at a side portion of the processing chamber. 2
However, for example, when the heating means 10 is provided and there is no space for installing the second gas introduction pipe 7 on the side wall of the processing chamber, As shown in FIG. 7, it is also possible to arrange the first and second gas introduction pipes 5 ′ and 7 ′ together in the upper part of the processing chamber. In this case, by using a two-system matrix shower structure 11 as the gas inflow structure, it is possible to mix the two gases at a location close to the object.

As described above, by employing the hot wall structure as shown in FIG. 7, the TEOS-containing gas introduced into the processing chamber can be maintained in a vaporized state until a reaction occurs. As a result, contamination in the processing chamber can be reduced, and the quality of the deposited film can be improved.

In describing the above embodiment, a TEOS-containing gas is used as a first processing gas, an O ₃ -containing gas is used as a second processing gas, and a TEOS-O ₃ oxide film is formed using these gases. Although reference was made to an example of film formation, the method of the present invention is not limited to such a type of processing gas. The present invention, in addition to TEOS containing gas as the first process gas, for example, TMOS (tetra-ethyl orthosilicate _{(Si (OCH 3) 4)} ), and OMCTS (octamethylcyclotetrasiloxane _{(Si 4 C 8 H 24 O} 4 )) And TMCTS (tetramethylcyclotetrasiloxane (S
It is also applicable to organic silicon source containing gases such as i ₄ C ₄ H ₁₆ O ₄ )). In addition to the O ₃ -containing gas, active oxygen (O ^{− *} ) or the like can be used as the second processing gas.

[0032]

As described above, according to the method of the present invention, the supply of the processing gas for forming a film on the object to be processed is performed in a vacuum atmosphere of less than 20 Torr, which is much lower than the conventional method. The TEOS-containing gas and the O ₃ -containing gas are less susceptible to the effects of radiant heat from the substrate heated to a temperature of 400 ° C., so that the above-mentioned gas which is reacted and consumed in the gas phase before reaching the substrate surface to be processed Minimize the amount of
A large amount of raw gas can be supplied to the surface of the object. As a result, the deposition rate of the TEOS-O ₃ oxide film is improved as compared with the case where the processing is performed at normal pressure or in a vacuum atmosphere of 20 Torr or more. In addition, TEOS-containing gas and O ₃
By mixing the contained gas as close as possible to the surface of the workpiece, the amount of raw gas that is reacted and consumed in the gas phase before approaching the surface of the workpiece is further reduced, and more raw gas is It can be used for a film forming reaction.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a P-TEOS / SOG / P-TEOS insulating film structure.

FIG. 2 P-TEOS / TEOS-O ₃ / P-TEOS
It is a schematic diagram of an insulating film structure.

FIG. 3 is a sectional view showing a first embodiment of a CVD apparatus for performing a semiconductor film forming method according to the present invention.

FIG. 4 is a graph showing a relationship between a pressure atmosphere and a deposition rate.

FIG. 5 is a graph showing the infrared absorption intensity of Si-0 in a TEOS-containing gas.

FIG. 6 is a graph showing a relationship between a pressure atmosphere, a deposition rate, and an etching rate of a deposited film.

FIG. 7 is a sectional view showing a second embodiment of a CVD apparatus for performing a semiconductor film forming method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CVD apparatus 2 Processing chamber 3 Mounting table 4 Heating device 5 First gas introduction pipe 6 Shower head 7 Second gas introduction pipe 8 Valve 9 Exhaust pipe

────────────────────────────────────────────────── (5) Continuation of the front page (56) References JP-A-6-59147 (JP, A) JP-A-5-55156 (JP, A) JP-A-4-101420 (JP, A) JP-A-3-101 214627 (JP, A) JP-A-1-212442 (JP, A) JP-A-3-123029 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/316 H01L 21 / 205 H01L 21/31

Claims (8)

(57) [Claims] 1. A film forming method for introducing a processing gas into a processing chamber capable of evacuating and forming a film on a surface of an object placed in the processing chamber, wherein the processing chamber has a vacuum atmosphere of less than 20 Torr. A first gas containing an organic silicon source is introduced from the upper surface of the processing chamber, and a component reacting with the organic silicon source of the first gas is introduced from a plurality of locations on the side wall of the processing chamber. A second processing gas to be introduced, and the first gas and the second gas near the surface of the object to be processed maintained at a temperature of 300 ° C. or more and less than 500 ° C. by a heating device.
Is mixed with the pressure, thereby reducing the pressure on the surface of the object to be processed.
A film forming method characterized by forming a film by a CVD process . 2. The method of claim 1, wherein the first gas is selected from the group consisting of TEOS (tetraethylorthosilicate), TMOS (tetramethylorthosilicate), OMCTS (octamethylcyclotetrasiloxane) and TMCTS (tetramethylcyclotetrasiloxane). Any one
The film forming method according to claim 1, wherein the two gases are one gas and one gas. 3. The method of claim 2, wherein the second gas is selected from the group consisting of ozone (O ₃ ) and active oxygen (O ^{− *} ).
The film forming method according to claim 1, wherein the two gases are two gases. 4. The method according to claim 1, wherein the first gas and the second gas are mixed in the vicinity of the surface of the object.
The method according to claim 1, 2, or 3. 5. A film forming apparatus comprising: a processing chamber capable of evacuating, a mounting table disposed in the processing chamber, on which a target object can be mounted, and a heating device for heating the target object. ,
Wherein the upper surface of the processing chamber is provided processing gas introducing path for introducing the first gas Rutotomoni, the sidewall of the processing chamber is a plurality of processing gas introducing path for introducing the second gas is provided And the first gas near the surface of the object to be processed.
And the second gas are mixed, and the pressure is reduced on the surface of the object to be processed.
A film forming apparatus characterized by forming a film by CVD processing . 6. The film forming apparatus according to claim 5, wherein the heating device is mounted on the mounting table. 7. The film forming apparatus according to claim 5, wherein an exhaust pipe is provided around the mounting table. 8. The film forming apparatus according to claim 5, wherein the first gas is introduced into the processing chamber via a shower head.