JP3391829B2 - Chemical vapor deposition method and apparatus using liquid raw material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to chemical vapor deposition for forming various deposited films such as metal films, semiconductor films or insulating films used in storage devices such as semiconductor devices or magneto-optical disks, or flat panel displays. Regarding law and equipment,
In particular, it relates to a chemical vapor deposition method and apparatus using a liquid raw material.

[0002]

Description of the Background Art A deposited film formed using a chemical vapor deposition method (CVD method) or an apparatus therefor (CVD apparatus) is
There are three major categories: metal film, semiconductor film, and insulating film.

Among them, in the case of a semiconductor film, first of all, there is a demand for a film forming method capable of obtaining a uniform film with few defects. On the other hand, it is needless to say that a uniform film is desired for the insulating film, but in addition, a film forming method excellent in step coverage is desired.
This is because many insulating films are used for insulation between wirings in an integrated circuit (IC) and protection of a surface having irregularities.

Further, also in the case of a metal film, a film forming method which is excellent in uniformity and step coverage like the above-mentioned insulating film is desired. Metal films are often used for IC wiring materials. In this case,
This is because step coverage in the openings is required to connect the upper and lower wirings through the openings called contact holes and three holes formed in the insulating film.

A conventional example of a CVD apparatus used for such a CVD method is schematically shown in FIG.

In FIG. 8, reference numeral 403 is a reaction chamber formed of a quartz tube or the like, and a plurality of substrate holders 410 for arranging and supporting a plurality of substrates 409 to be film-formed are provided therein.

An exhaust pipe 408 is connected to a main pump 404 such as a mechanical booster pump and an auxiliary pump 405 such as a rotary pump, and exhausts the reaction chamber 403 from here.

On the other hand, as a gas supply system, a cylinder (bubbler) 402 with a bubbling mechanism for bubbling a liquid raw material, a gas pipe 406 for introducing a carrier gas for bubbling, a valve 401, and a reaction chamber 403. A gas pipe 407 for introducing the vaporized raw material is provided.

Although such a conventional CVD apparatus exhibits sufficient performance as long as the most general film formation is performed,
It may not be suitable for the CVD method which has recently been required for fine processing and large area.

That is, there is a general lack of versatility that it can be applied to any CVD method.

An example of this problem will be described.

Recently, attention has been paid to aluminum using a CVD method instead of a sputtering method as a wiring material of a highly integrated semiconductor device called VLSI or ULSI.
Especially CV using organoaluminum as organic compound
It has been reported that in the D method, the deposition conditions greatly differ between the insulator and the conductor, and selective deposition in which aluminum is deposited only on the conductor or the semiconductor is possible. This selective deposition of aluminum is extremely useful when manufacturing a fine integrated circuit, and is an alternative technique when the depth-hole diameter ratio (aspect ratio) exceeds 1, in particular. It enables aluminum wiring that cannot be realized by the sputtering method. The reason why the wire breaks when the aspect ratio of the opening is increased by the sputtering method will be described with reference to FIG. In Figure 9,
Reference numeral 201 is a single crystal silicon substrate, 202 is an insulating film such as silicon dioxide, and 203 is a wiring material such as aluminum.

(A) shows the state of wiring when the aspect ratio is small, and (b) shows the state of wiring when the aspect ratio exceeds 1 and is large.

While the recesses 204 and the voids 205 are formed by the above-mentioned sputtering method, as shown in FIG. 9C, in the selected volume by the CVD method, aluminum 303 is completely contained in the opening. The probability of being filled and breaking is extremely low.

Here, 301 is a silicon substrate, 302 is an insulating film such as silicon dioxide, 303 is a metal material such as aluminum deposited by a CVD method, and 304 is an aluminum wiring deposited by a sputtering method or a CVD method.

As described above, when the fine semiconductor device wiring is manufactured by the CVD apparatus shown in FIG. 8, the carrier gas CGS such as hydrogen is decompressed by the decompression valve 401 and the bubbler 40 is depressurized.
Transport to 2. As a material gas capable of selectively depositing aluminum, dimethyl aluminum hydride (DM
Many of them are in a liquid state at room temperature, such as AH) and triisobutylaluminum (TIBA). Therefore, a step of causing foaming in the bubbler 402, that is, bubbling is performed, and a mixed gas composed of a carrier gas and a saturated vapor of organic aluminum such as DMAH is introduced into the reaction chamber 403. The mixed gas is the heated semiconductor substrate 4
On 09, pyrolysis occurs and aluminum is deposited on the substrate by surface reaction with the substrate.

The unreacted reaction gas in the reaction chamber 403 is exhausted to the outside by using the main pump 404 and the auxiliary pump 405.

However, if there is a change in the equipment environment such as a change from the experimental CVD apparatus in which stable selective deposition is carried out to the mass production CVD apparatus, the selectivity obtained up to now is lost. Such problems may occur.

This means that not only the metal film but also the semiconductor film will have more defects and the insulating film will have lower step coverage.

According to the knowledge of the present inventors, although the detailed reason will be described later, it has been found that the conventional CVD apparatus has the following reasons that make versatility poor.

One is that the controllability of the mixing ratio of the liquid compound as the raw material and the other gas is not good.

The second is that the mixing of compounds is changed by the temperature change near the bubbler.

Thirdly, the mixing ratio of the compounds changes depending on the remaining amount in the bubbler.

(Object of the Invention) An object of the present invention is to provide a chemical vapor deposition method and apparatus capable of stably forming a high-quality deposited film even in the presence of changes in environmental conditions and operating parameters. To provide.

Another object of the present invention is to provide a chemical vapor deposition method and apparatus which are excellent in operability and mass productivity and can reduce the manufacturing cost of various devices to be manufactured.

Still another object of the present invention is to provide a chemical vapor deposition method and apparatus capable of forming a deposited film which is uniform over a large area and has few undesirable defects and excellent step coverage. Especially. The structure for achieving the object of the present invention is: a reaction chamber, an exhaust unit for exhausting the reaction chamber, and a substrate holding unit for holding a substrate in the reaction chamber,
In a chemical vapor deposition apparatus comprising: an introduction unit that introduces a raw material gas into the reaction chamber, the introduction unit includes a first setting unit that sets a supply amount of a liquid source material to a desired amount, A vaporizer provided downstream of the first setting means for vaporizing a liquid raw material and a vaporizer provided upstream of the vaporizer and introduced into the vaporizer have different gas amounts. Second setting means for setting a desired amount, a plate-shaped member having an opening for introducing a mixed gas of the vaporized raw material and the gas arranged in the vaporizer into the reaction chamber, and the vaporizer And a jetting means for jetting the raw material as droplets therein, and the plate member is provided with a heating element for keeping the temperature inside the vaporizer constant. It is a chemical vapor deposition apparatus.

Another structure for achieving the object of the present invention is as follows.
A reaction chamber, using an exhaust means for exhausting the reaction chamber, a substrate holding means for holding a substrate in the reaction chamber, and introducing means for introducing a material gas into the reaction chamber, the device having the
In a chemical vapor deposition method that deposits a thin film on a substrate,
The liquid substance is weighed in liquid state, and then it is dropped into the vaporizer as droplets.
After supplying and measuring a gas different from the raw material,
Supply into the vaporizer and heat the raw material in droplet form in the vaporizer
And vaporize it by contacting with the plate member
The mixed gas in the vaporizer is mixed and provided in the plate member.
To the reaction chamber through an open hole
It is a science vapor deposition method.

[0028]

[0029]

Before describing the embodiments of the present invention, the technical matters found in the present invention will be described below.

For example, CVD using DMAH and hydrogen
When selective deposition is carried out by the method, the following 2 reactions may proceed on the surface of the semiconductor substrate having the insulating film having the openings. 2Al (CH ₃ ) ₂ H + H ₂ → 2Al + 4CH ₄ (1) 2Al (CH ₃ ) ₂ H → 2Al + 2CH ₄ + C ₂ H ₆ ...
(2)

In this case, if the reaction proceeds as in (1), the selectivity between the semiconductor surface and the insulator surface is secured. However, if the simple thermal decomposition reaction as in (2) proceeds, the selectivity between the semiconductor and the insulator may not be completely obtained. The cause is DM in the mixed gas
That is, the molar ratio of AH and hydrogen has a significant influence on the deposition state.

In order to avoid this problem, it seems that it is sufficient to mix hydrogen in excess. However, if hydrogen is supplied in excess over a certain amount, the reaction in the reaction chamber falls into a supply rate-determining state. The deposition rate varies depending on the aperture diameter. "" The aluminum embedding shape has a facet surface as shown in FIG. 10, and the flat embedding is removed. "
There are problems such as. After all, unless the mixing ratio of DMAH and hydrogen is optimally controlled, a CVD method that leads to commercial success as a semiconductor manufacturer cannot be achieved. The optimum mixing ratio will be examined below.

The molar mixing ratio in the case of DMAH and hydrogen is determined by the ratio of the saturated vapor pressure of DMAH and the partial pressure of hydrogen at the bubbler outlet. That is,

[0035]

[Outer 1] P _DMAH is uniquely determined by the temperature, and is about 1 to 2 torr at room temperature.

[0036]

[Outside 2] Can be controlled by the pressure reducing valve, but the control accuracy is almost determined by the accuracy of the pressure reducing valve. P _DMAH and

[0037]

[Outside 3] If you want to control the ratio of

[0038]

[Outside 4] Is about 10 torr, and the pressure reducing valve needs to control the pressure in several torr units. However, with current pressure reducing valve technology, this is very difficult.

As in (3) above, the molar mixing ratio is P _DMAH
It depends on the temperature, because P _DMAH is just saturated vapor pressure. FIG. 11 shows the temperature dependence of the saturated vapor pressure of DMAH.

Thus, P _DMAH changes exponentially with temperature. On the other hand, hydrogen is a gas at room temperature, so temperature changes

[0041]

[Outside 5] Does not change exponentially. In other words, the molar mixing ratio changes greatly with changes in temperature near the bubbler.

Also, the hydrogen partial pressure at the bubbler outlet

[0043]

[Outside 6] Does not match the hydrogen pressure at the bubbler inlet,

[0044]

[Outside 7] There is a relationship. here,

[0045]

[Outside 8] ρ: Specific gravity of organic metal h: Distance from bubbling nozzle port to cylinder liquid level c: Pressure conversion constant In this case, the variable that can be controlled by the regulator is

[0046]

[Outside 9] However, since the value of h becomes smaller as the device is used,

[0047]

[Outside 10] Is changing. After all this

[0048]

[Outside 11] To keep constant

[0049]

[Outside 12] Needs to be corrected by the liquid remaining in the bubbler. However, this is a technique with great difficulty in terms of device configuration. As described above in detail, it has been difficult to say that the conventional CVD method has sufficient controllability of the raw material gas in order to obtain wide versatility and optimum deposition conditions.

According to the present invention, a raw material such as an organic metal which is in a liquid state at room temperature is metered in a liquid state and the supply amount is controlled, and thereafter, particles or vaporized by using a vibrator or a venturi means. By heating it before the reaction and feeding it into the reaction chamber as a gas, the mixing ratio with the carrier gas or other reaction gas can be accurately measured without being affected by the fluctuation of the saturated vapor pressure of the raw material. Can be controlled.

According to the invention, this allows any C
The VD method can be performed properly.

Other than the metal film, for example, in the case of a compound semiconductor, the composition ratio of elements can be well controlled, and a uniform semiconductor film or a semiconductor film with a controlled hand gap can be easily formed. In the case of an insulating film, SixOy or Si
It is easy to control x and y in xNy, and it is possible to easily form a large-area film having a uniform dielectric constant.

In addition, a large amount of raw material can be transported, and a uniform film can be easily formed on a large area substrate or a large number of substrates at a high deposition rate.

(Description of preferred embodiments) In a preferred embodiment of the present invention, the raw materials are metered in a liquid state and controlled so as to set the supply amount of the raw materials to obtain a desired mixing ratio to a desired amount. CV having, as introduction means, a control means for controlling and a vaporization means provided on the downstream side of the control means, that is, on the reaction chamber side
The apparatus D and the apparatus are used to measure the raw material liquid in a liquid state, set the supply amount to a desired amount, and then introduce the same into the vaporizing means to vaporize it to almost 100%.

As the CVD source material used in the present invention, a liquid material is used in the environment in which the CVD apparatus is used. More preferably, it is a liquid at normal pressure and normal temperature (for example, 10 to 30 ° C.).

Specifically, trimeryl aluminum (TM
A), triethyl aluminum (TEA), triisobutyl aluminum (TiBA), dimethyl aluminum hydride (DMAH), diethyl aluminum hydride (DEAH), monomethyl aluminum hydride (MMAH), triethyl indium (TEI).
n), trimethylindium (TMIn), triethylgallium (TEGa), trimethylgallium (TMG)
a), dimethylzinc (DMZn) trichlorosilane (SiHCl ₃ ), silicon tetrachloride (SiC
l ₄ ), tetraethyl orthosilicate (TEOS),
Fluorotrietoxylan (FOTES), POC
_{l 3, BBr 3, Sn (} CH 3) 4 and the like.

In particular, the organometallic compound has a relatively low vapor pressure at room temperature and atmospheric pressure and is difficult to mass-transport, so that it is preferably used in the CVD method according to the present invention.

H ₂ , O ₃ , NH ₃ , NO, N _{2 and the} like are used as the reaction gas mixed with the above-mentioned raw material, and an inert gas such as Ar is used if necessary.

Of course, when forming a compound film or controlling the conductivity type, well-known doping gases such as PH ₃ and As are used.
H ₃ , BF ₃ , B ₂ H ₆ , SiH ₄ , and Si ₂ H ₆ are used together.

The deposited film formed by the present invention includes Al, In, Ga, Zn, Sn as a metal film, GaAs, GaAlAs, InP, ZnS as a compound semiconductor film.
e, ZnSeTe, etc., Si, SiGe, or SiO, SiON, SnO, InSnO, ZnO, Z as an oxide film
nAlO, InN, AlN, SiN, B as a chambering film
N, etc.

When a plurality of liquid source materials are used, for example, when a GaAlAs film is formed using TMG and TMA, two control means and two vaporization means are provided in each reaction chamber. By providing for
It is possible to precisely control the composition ratio of a compound such as a GaAlAs film.

Next, a more preferable structure of the vaporizing means used in the present invention will be described. It is desirable that the liquid source material introduced into the vaporizing means is vaporized by the vaporizing means to be almost 100%. For that purpose, first, the liquid is made into liquid droplets (the liquid droplets referred to here are fine particles of liquid such as mist). Also included)
It is introduced into the vaporizing chamber of the vaporizing means.

Further, in the vaporizing means, it is desirable that the pressure in the vaporizing chamber be lowered stepwise or continuously along the flow direction of the raw material gas.

Furthermore, it is desirable to keep the temperature of the vaporization chamber at a temperature lower than the substrate temperature in the reaction chamber and higher than the temperature of the liquid source material supply system up to the vaporization means.

As still another vaporizing means, a liquid source material is made into liquid droplets to promote vaporization, and a jet head or a variable head for jetting the liquid source material pressurized from a fine opening is used. A liquid ejecting means such as a venturi mechanism may be used. In the case of the variable venturi mechanism, it also serves as control means for measuring and controlling the supply amount of the raw material substance in a liquid state.

In order to create a pressure difference or a pressure gradient in the vaporizer, at least one plate-shaped member having an opening is arranged in the gas flow passage as the pressure changing means, and the gas is supplied through the opening to the reaction chamber. It is desirable to be configured so as to be introduced into. It is even more preferable to arrange a plurality of plate-like members so that the aperture diameter becomes smaller from the upstream side toward the downstream side.

On the other hand, it is desirable to provide heating means in the vaporizer so as to keep the temperature of the gas in the vaporizer constant.
Examples of such heating means include a heating resistor and a lamp, which are provided inside or outside the vaporizer. Especially, in order to make the strength of the gas in the vaporizer uniform, it is optimal to provide a heating element inside the vaporizer.

Since the above-mentioned pressure conditions and temperature conditions are appropriately set according to the raw materials used and the scale of the apparatus,
It is desirable to configure the vaporizing means by appropriately combining the liquid ejecting means, the pressure changing means and the heating means.

If it is desired to avoid the CVD apparatus from having a complicated structure, it is desirable to devise the structure of the heating means. This is because the device configuration becomes large in order to perform precise control as the liquid ejecting unit and the pressure changing unit. On the contrary, the heating means can be controlled in a fairly wide range and precisely only by arranging the heating element and the temperature sensor and controlling the calorific value.

Specifically, a heating element is provided on the plate member as the pressure changing means so that the in-plane temperature distribution of the plate member becomes uniform. Since the temperature tends to fluctuate near the opening of the plate member due to the pressure difference, the heating element is arranged near the opening.

Further, when a plurality of plate-like members and liquid ejecting means are combined as in the embodiment described later, at least the plate-like member closest to the upstream liquid ejecting port is provided with the heating element. . This is because it is important to control the temperature at the position where most of the raw material is vaporized and mixed with other gas for the first time.

The temperature at each position, that is, the substrate surface temperature (Tsu
b) The temperature condition is set so that the temperature (Tspy) of the liquid source material supply system and the temperature (Teva) of the plate-shaped member in the vaporizer are specifically Tsub>Teva> Tspy.

The reaction chamber used in the present invention can be formed by an insulating reaction tube such as quartz or a reaction tube made of metal, and the reaction tube is one that can accommodate one or more substrates for film formation therein.

As the exhaust means, a mechanical booster pump, a rotary pump, an oil diffusion pump, a turbo molecular pump, etc. may be used alone or in combination.

Further, the substrate is held in the reaction chamber by the substrate holding means with the film formation surface facing upward, downward, sideways or diagonally upward or diagonally downward.

A gas introducing means, which will be described later, may be attached to the CVD apparatus configured as described above.

[0077]

【Example】

(Embodiment 1) FIG. 1 is a schematic diagram showing a CVD apparatus according to Embodiment 1 of the present invention.

Reference numeral 101 denotes a container for containing a raw material substance in a liquid state, and one of the conduits is connected to a cylinder 114 containing a pressurizing gas such as Ar or N ₂ through a pressure controller 116.

The other conduit is connected to the upstream side of the reaction chamber 106 via a controller 102 capable of detecting the liquid flow rate and controlling the flow rate with high accuracy.

On the upstream side of the reaction chamber 106, a mass flow controller 103 as a gas flow rate controller is separately provided,
It is connected to the gas cylinder 113.

Further, a heating means is provided on the upstream side of the reaction chamber 106, and the heating means is a quartz plate 109 having a hole.
And a heater 105 and a heating controller 115. A substrate holder 108 that holds a plurality of substrates 107 is provided in the reaction chamber 106. Here, the substrate holder 108 includes a resistance heater for heating the substrate 107.

An exhaust device 112 is provided downstream of the reaction chamber 106.
Is provided, and the inside of the reaction chamber is maintained at a desired pressure by controlling the supply amount and the exhaust amount of the raw material.

FIG. 2 is an enlarged schematic view of the vaporizer (evaporator portion) on the upstream side of the reaction chamber 106 of FIG. 1, in which a plurality of quartz plates 109 having a plurality of openings 120 are arranged side by side. An introduction head 12 provided with a piezo oscillator 104 as an introduction means of the liquid source material upstream thereof.
1 is provided. FIG. 3 is a schematic sectional view of the introduction head 121.

The glass introducing tube 118 is connected to the connecting member 117.
Is connected to the upstream wall 122 of the reaction chamber 106. A piezo oscillator 104 is provided around it,
It vibrates by the pulse signal voltage from the drive circuit 111.
The liquid source material, which is supplied at a high pressure while the supply amount is controlled, is ejected from the opening 123 and is divided into droplets by the vibration energy received from the piezoelectric vibrator 104 during the ejection. This principle is similar to the well-known inkjet technology.

The droplets of the raw material substance thus ejected are heated by the heater 105 and further hit the quartz plate 109 to be vaporized. The heating temperature, the distance and position between the quartz plate 109 and the opening 123, and the pressure and flow rate of the gas introduced from the cylinder 113 are adjusted so that the droplets are vaporized most efficiently. Reference numeral 119 is a control circuit including an operation panel, a memory, and a microcomputer, which includes a liquid flow rate controller 102, a mass flow controller 103,
It controls the operation of the heating controller 115. Therefore,
The operator can easily set the optimum deposition conditions by operating the control circuit 119.

Further, in this embodiment, an insulating ceramic plate can be used instead of the quartz plate 109 used as a constituent element of the vaporizing means.

Further, in this embodiment, gas was used for the pressure feed of the liquid raw material, but it is also possible to use a micro pump.

(Embodiment 2) FIG. 4 is a schematic view showing a CVD apparatus according to Embodiment 2 of the present invention. The arrangement of the substrates in the reaction chamber 5 and the exhaust device are the same as those shown in FIG.

The carrier gas 2 is piped so as to be sent to the gas introduction pipe 23 via the mass flow controller 21 and the valve 22. The liquid source material 11 is contained in the tank 1. One end of the upper part of the tank is opened to the front of the venturi of the gas introduction pipe 23 and one end of the lower part is opened to the venturi part of the gas introduction pipe 23 to eject the raw material. 32 is formed. The gas introduction pipe is provided with a throttling venturi 3 which serves both as a supply amount control means of liquid raw material and a raw material gas introducing means, and a throttle valve 31 and a throttle adjusting mechanism 3
3 and 3.

With the above structure, the carrier gas is sent to the gas introducing pipe 23, and then the flow path is narrowed by the throttle valve 31, so that the pressure in the throat portion is reduced with respect to the pressure in the introducing pipe 23, and the pressure difference ΔP. Cause Due to this pressure difference, the raw material 11 is sucked, becomes droplets from the throat 32 portion, and is jetted to form a mixed gas with the carrier gas.

Here, ρ _c and ρ _s are the specific gravities of the carrier gas and the raw material, Ac is the opening area of the carrier gas flow passage in the venturi portion, As is the opening area of the throat raw material flow passage, and h is the liquid of the raw material. If the difference between the surface height and the height of the throat tip is, the carrier gas flow rate Gc is determined by Bernoulli's theorem.
The mixing ratio R of the raw material flow rate Gs is as follows.

[0092]

[Outside 13]

Here, Cc and Cs are called flow coefficients of the carrier gas and the raw material, and are constants depending on the Reynolds number and the shape of the channel. Accordingly, if the difference h ~ 0 of liquid level, the mixing ratio R is RocAc / As next flow area ratio, i.e., a stable controllable only by mechanical aperture adjustment mechanism 33.

On the other hand, the flow rate can be controlled by the mass flow controller 21 for the carrier gas.

The mixed gas of the droplet-shaped raw material and the carrier gas is sent to the evaporator section 4 of FIG. Evaporator 4
Is a plurality of plates 41 and a heating mechanism 42 for rectifying the gas flow.
Composed of and.

As shown in FIG. 5, the plate is a quartz plate having a large number of through holes, an insulating ceramic, or the like. In the evaporator 4, the mixed gas is heated, the raw material is vaporized and rectified, and the raw material is uniformly transported to the reaction chamber 5. The heating temperature of the evaporator is as high as possible in which the saturated vapor pressure is high, and the heat of the raw material is high. It is preferably lower than the decomposition temperature. The reaction chamber 5 also has a heating mechanism 6, a substrate (not shown) is arranged, and the raw material is thermally decomposed on the surface of the substrate,
Deposit a deposited film. The reaction chamber is evacuated by the mechanical booster pump, the rotary pump, etc. as described above.

(Embodiment 3) FIG. 6 is a schematic diagram for explaining a CVD apparatus according to Embodiment 3 of the present invention, and further improves the structure of the portion for introducing the source gas in Embodiment 2 shown in FIG. It was done.

Only the part different from the second embodiment will be described in detail.

In this embodiment, the liquid level control method is adopted in the above-mentioned second embodiment, and the float 13 is provided in the raw material tank 1. The float 13 is connected to the needle valve 12, and the opening of the needle valve is controlled by the height of the liquid surface. The raw material 11 is introduced into the tank through a needle valve. In this example, there are many moving parts such as floats, and dust generation is likely to be a problem.Therefore, there are few friction parts.For example, by combining a liquid level sensor with electrical contacts or an optical liquid level sensor with an electromagnetic valve, the liquid level It is also possible to control.

By the above method, the controllability of the mixing ratio is further improved.

(Embodiment 4) This embodiment is an improvement of the evaporator portion shown in FIGS. 2 and 5, and has a structure capable of forming a gas flow having a uniform temperature distribution.

In the above-mentioned embodiment, the heater 105 attached to the outside of the evaporator portion is used in order to keep the evaporator portion at 80 ° C., for example.

Further, unless the temperature of the gas in the evaporator section is kept uniform, it is difficult to form the film well.

FIG. 12 is a graph showing the correlation between the temperature inside the evaporator and the transportation efficiency of the vaporized source gas.
When organoaluminum is used as the liquid raw material, if the temperature inside the evaporator is 100 ° C. or lower and 40 ° C. or higher, almost 100% of the liquid raw material is vaporized and transported into the reaction chamber.

When the temperature is lower than 40 ° C., it is not completely vaporized and tends to remain as droplets in the evaporator portion. When the temperature is higher than 100 ° C., about 0.1% of the raw material gas is decomposed in the evaporator portion. Then Al begins to precipitate. Precipitated Al blocks the openings of the quartz plate and prevents the flow of the raw material gas, so that the transport efficiency is lowered beyond the decomposition rate of 0.1%.

FIG. 13 shows how this affects the film formation. FIG. 13 shows the correlation between the temperature inside the evaporator and the deposition rate of the obtained Al film.

Liquid D in the CVD apparatus shown in FIG.
The flow rate of MAH and the flow rate of H ₂ gas are measured and adjusted so that the molar ratio is 1: 1. Single component S: A on the wafer
The result of measuring the deposition rate of 1 is plotted against the temperature in the evaporator part.

In FIG. 13, the temperature inside the evaporator is set to 8
It is shown as a relative value with the Al deposition rate at 0 ° C. as 1. As is clear from the figure, when the temperature is lower than 60 ° C., the vapor pressure of DMAH becomes too low and the reaction is rate-limited, so that the deposition rate becomes extremely low. On the other hand, the temperature is 10
When the temperature exceeds 0 ° C, the deposition rate does not increase due to the decrease in transport efficiency.

That is, precise control of the temperature inside the evaporator is important in the method of performing CVD after vaporizing the liquid material.

Moreover, it has been found that this temperature control must be precisely controlled while the gas is flowing.

FIG. 14 is a graph showing the in-plane temperature distribution of the quartz plate 109 arranged in the evaporator section.

The white circles in FIG. 14 show the temperature distribution of the quartz plate when no gas is flowing (initial state), and the black circles are the temperature distribution when gas is flowing (operating state). As is clear from FIG. 14, since the gas flows without staying in the vicinity of the opening 120 of the quartz plate 109, the temperature is considerably lower than the initial set temperature. This is because the new gas is sequentially supplied, so that heat is generated in the vicinity of the opening 120 to lower the temperature. Such in-plane temperature distribution changes depending on the size of the opening of the quartz plate. Generally, the larger the openings and the larger the ratio of the openings to the quartz plate, the larger the in-plane temperature distribution. However, the aperture on the most upstream side cannot be made small in order to satisfy the pressure condition and gas supply amount in the apparatus.

FIG. 15 shows the correlation between the above-mentioned in-plane temperature distribution and the quality of the selective deposition of the obtained Al film.

As such, the larger the in-plane temperature distribution, the worse the selectivity during selective deposition.

In this embodiment, the structure of the evaporator portion is improved so that such in-plane temperature distribution becomes smaller.

FIG. 16 is a schematic view showing the evaporator portion according to this embodiment.

In this embodiment, a temperature-adjustable baffle plate assembly 600 is used instead of the plurality of quartz plates shown in FIGS.

FIG. 17 shows the components of the assembly 600, in which three quartz baffle plates 602, 603 and 604 of different sizes are incorporated in the holder 601.
Another baffle plate 63 is provided on the opposite side of the holder 601.
Attach 0 closely.

Three baffle plates 602, 603, 604
A narrow space is formed between them while being attached to the holder 601.

FIG. 18 is a plan view of the holder 601 seen from the XX 'direction in FIG. A plurality of grooves are formed in the holder, and heaters 620, 621, 623 whose heat generation amounts are independently controlled are embedded in the holder at different positions in the plane as shown in FIG. There are also thermocouples 62 in 4 places.
4, 625 and 626 are embedded so that the in-plane temperature distribution can be detected. Also, an opening 611 is formed in the center.
Are provided in plural.

FIG. 19 shows a holder 60 from the side opposite to that of FIG.
It is the top view which looked at 1.

Similarly, FIG. 20 shows the baffle plate 602 as shown in FIG.
Is a plan view showing the baffle plate 603, and FIG. 22 is a plan view showing the baffle plate 604.

Baffle plates 602 and 6 to the holder 601
In the attached state of 03 and 604, the opening 612 and the opening 613 are provided at positions where they do not overlap each other.
Similarly, the opening 613 and the opening 614 are fixed so as not to overlap each other.

Of the three baffle plates, the aperture 612 has the largest diameter and the aperture 614 has the smallest diameter.
The baffle plate 602 has the highest aperture ratio, and the baffle plate 604 has the lowest aperture ratio.

According to the present embodiment, after adjusting the current applied to the heating heater in the holder to a uniform in-plane temperature distribution of about 80 ° C. (white circles in FIG. 14) based on the temperature detected by the thermocouple. As a result of flowing the gas, it is possible to obtain an in-plane temperature distribution as shown by the mark X in FIG.

Then, if the energization amount is slightly increased, an in-plane temperature distribution almost close to a white circle can be obtained.

Therefore, according to the present embodiment, the in-plane temperature is kept uniform within ± 1% at a predetermined temperature within the range of 60 ° C. to 100 ° C., and the transportation efficiency is almost 100%. The maximum deposition rate can be achieved, and an Al film having excellent selectivity can be formed.

As described above, in the CVD apparatus, a variable venturi is provided in the carrier gas flow path to control the supply amount of the liquid source material, and at least the liquid source material is made into a droplet shape. After that, it is vaporized by the heating rectifying mechanism and the mixed gas with the carrier gas is introduced into the reaction chamber, whereby the following effects are produced.

The liquid raw material having a low saturated vapor pressure is efficiently transported to the reaction chamber, and the film deposition rate is improved.

Vaporization for improving the controllability of the mixing ratio of the carrier gas and the raw material is performed by an evaporator, and even if there is a temperature change near the raw material tank, the raw material concentration is not affected.

Eventually, the film can be deposited with excellent flatness and uniformity.

Further, in the above-described method of introducing the raw material of the present invention, one variable venturi is provided in one flow path of the carrier gas, but the flow path of the carrier gas is divided into a plurality of gases. A configuration is also possible in which a plurality of variable venturis are provided in each of the introduction pipes and a plurality of raw materials are ejected in parallel. The plurality of mixed gas paths may be integrated into one before the evaporator, or the evaporator may be configured in each circuit.

(Experimental Example 1) An example of forming a deposited film using the CVD apparatus shown in FIG. 1 will be described below.

DMAH was used as the liquid source gas. First, the outline of the film forming procedure will be described.

Bubbler 1 with Argon as Inert Gas
The inside of 01 is pressurized and is sent as a liquid to the liquid flow rate controller 102 side under pressure. At this time, the pressure of argon is about 0.5 atm (380
It is desirable to set to torr).

A commercially available product is used as the micro liquid flow meter 102. Maximum control flow rate 0.2 cc suitable for use in this example
Some of them are in charge of about 500 cc in the gas state.
The DMAH whose flow rate is controlled by the micro liquid flow meter 102 is pressure-fed to the piezoelectric vibrator 104, where 1 to 50 KH.
Vibration energy of about z can be applied. As a result, particles with a particle size of 10 to 50 μm are atomized and become DMAH.
Is injected into the upstream vaporization chamber upstream of the reaction chamber 106.
The injected DMAH is preheated here, hits the perforated quartz plate 109, and vaporizes here. As shown by the arrow in FIG. 2, the vaporized source material is introduced into the reaction chamber through the hole portion 120. Here, since the quartz plate is kept at about 80 ° C. by the pre-heater 105, DMAH
Completely vaporizes when enters the reaction chamber.

On the other hand, the flow rate of hydrogen is controlled by the mass flow controller 103, and the hydrogen is pressure-fed to the quartz plate 109. Here, it is mixed with DMAH and introduced into the reaction chamber like DMAH.

In the reaction chamber 106, a heater 108 is installed corresponding to each substrate 107 and causes thermal decomposition on the surface of the substrate 107. This reaction is mainly based on the above-mentioned reaction formula (1). Sufficient selectivity is exhibited on the substrate having the surfaces of the semiconductor and the insulator, and the embedded state as shown in FIG. 7C can be obtained.

As a typical deposition condition, hydrogen is used at 500 SC
The liquid flow rate of CM and DMAH is 0.04 cc, the pressure of the reaction chamber is 1.2 torr, and the substrate heating temperature is 260 ° C to 350 ° C.
More preferable temperature is 270 ° C. for good deposition. According to this condition, it is possible to deposit aluminum having excellent flatness and film quality. According to the above procedure, a deposited film was formed on the substrate as described later.

First, the substrate was prepared. As a substrate, one side of a low resistance single crystal Si wafer is 0.5 μm to 2.
There was prepared an insulating film having 1000 openings with a diameter of 0 μm. A groove 1410 is formed in a part of it by etching.

FIG. 7A is a schematic view showing a part of this substrate. Here, 1401 is a single crystal silicon substrate as a conductive substrate, and 1402 is a thermal silicon oxide film as an insulating film (layer). Reference numerals 1403 and 1404 denote openings (exposed portions) having different diameters. 1410 is Si
It is an exposed groove.

Next, ten of these substrates were placed on the substrate holder 108 with a heater in the reaction chamber 106.

Then, the mixed gas was introduced into the reaction chamber under the following conditions to selectively deposit Al in the openings.

[0144]

[Table 1]

Thus, the obtained film was formed only in the opening and was made of single crystal Al.

Then, an Al film 1406 was formed on the above-mentioned substrate by a well-known sputtering method and patterned as shown in (D) to form wiring.

In order to check the contact state between the Al 1405 in the opening thus obtained and the Al film 1406 formed by sputtering, the wiring was opened and opened by a tester.
We inspected for shorts. As a result, no defective part was found in all the substrates having 1000 openings.

Comparative Example 1 Using the apparatus shown in FIG. 8 as a CVD apparatus, an Al film was formed under the same procedure and under the same conditions as in Experimental Example 1 above. However, in the case of Comparative Example 1, DMAH was bubbled with hydrogen.

When an open / short test was conducted on 10 substrates each having 1000 holes thus obtained, contact defects (open defects) at several to several tens of spots were found on each of the three substrates. I was seen.

(Experimental Example 2) A substrate (Si wafer) having 1000 holes was prepared in the same manner as in Experimental Example 1, and FIG.
An Al film was formed in the same manner as in Experimental Example 1 using the CVD apparatus shown in FIG.

The conditions in the Al deposition process are as follows.

[0152]

[Table 2]

When an open / short test was conducted on 10 substrates each having 1000 holes thus obtained, only a few defects were found on one substrate.

(Experimental Example 3) As the substrate, Al in Experimental Example 1 was used.
An insulating film was formed on the substrate by using the film-formed product ((D) of FIG. 7) using the CVD apparatus shown in FIG.

First, before the experiment, the CVD apparatus was decomposed and washed and baked.

A thin silicon oxide film having a thickness of about 1 μm was formed by a CVD method using TEOS as a raw material and ozone (O ₃ ) as a reaction gas.

Observation of the obtained silicon oxide film showed that it was excellent in step coverage although it was as thin as 1 μm.

(Experimental Example 4) Similarly to Experimental Example 3, TEOS and O were used.
The ₃ and CVD method using, as obtained in Experimental Example 2 Al
A silicon oxide film was formed on the substrate on which the film was formed.

The CVD apparatus used was the one shown in FIG. 4 in which electrodes for plasma generation were arranged as in Experimental Example 3.

The obtained silicon oxide film showed excellent step coverage as in Experimental Example 3.

[0161]

As described above, according to the present invention, the supply amount of the raw material is controlled with high accuracy by measuring the raw material in a liquid state, and then vaporized and transported into the reaction chamber. As a result, precise supply amount control can be performed without being affected by temperature fluctuations and the amount of liquid remaining in the cylinder. Therefore, the control of the film forming parameters becomes easy and the versatility increases.

Further, according to the present invention, even a raw material having a very low vapor pressure at room temperature can be transported in a large amount, and the deposition rate can be improved and the processing speed can be increased.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an entire CVD apparatus according to a first embodiment of the present invention.

2 is an enlarged schematic view showing a vaporizer portion of the CVD apparatus shown in FIG.

FIG. 3 is an enlarged schematic view showing a portion of an ejection head of the CVD apparatus shown in FIG.

FIG. 4 is a schematic diagram of a CVD apparatus according to a second embodiment of the present invention.

5 is an enlarged schematic view of a vaporizer portion of the CVD apparatus shown in FIG.

FIG. 6 is a schematic diagram showing a Venturi mechanism of a CVD apparatus according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram showing a procedure for forming a deposited film using the chemical vapor deposition method according to the present invention.

FIG. 8 is a schematic diagram showing an example of a conventional CVD apparatus.

FIG. 9 is a schematic view showing a state of a deposited film formed.

FIG. 10 is a schematic diagram showing a state of a deposited film formed.

FIG. 11 is a graph showing the relationship between temperature and vapor pressure of an example of a raw material substance in a conformal form.

FIG. 12 is a diagram showing the relationship between the temperature in the evaporator section and the efficiency of raw material gas transport.

FIG. 13 is a diagram showing the relationship between the temperature in the evaporator section and the deposition rate.

FIG. 14 is a diagram for explaining in-plane temperature distribution of a quartz plate.

FIG. 15 is a diagram showing a relationship between in-plane temperature distribution of a quartz plate and selectivity.

FIG. 16 is a schematic diagram showing an evaporator section of a CVD apparatus according to Example 4 of the present invention.

FIG. 17 is a schematic cross-sectional view for explaining the configuration of the quartz plate assembly of Example 4.

FIG. 18 is a schematic cross-sectional view for explaining the configuration of the quartz plate assembly of Example 4.

FIG. 19 is a schematic cross-sectional view for explaining the configuration of the quartz plate assembly of Example 4.

FIG. 20 is a schematic cross-sectional view for explaining the configuration of the quartz plate assembly of Example 4.

FIG. 21 is a schematic cross-sectional view for explaining the configuration of the quartz plate assembly of Example 4.

FIG. 22 is a schematic cross-sectional view for explaining the structure of the quartz plate assembly of Example 4.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-130820 (JP, A) JP-A-1-246366 (JP, A) JP-A-3-126872 (JP, A) JP-A-5- 106047 (JP, A) JP-A-1-119674 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 16/00-16/56 H01L 21/205

Claims (9)

(57) [Claims] 1. A reaction chamber, an exhaust unit for exhausting the reaction chamber, a substrate holding unit for holding a substrate in the reaction chamber, and an introducing unit for introducing a source gas into the reaction chamber. In the chemical vapor deposition apparatus, the introduction means includes a first setting means for setting a supply amount of the liquid source material to a desired amount, and a liquid source provided downstream of the first setting means. A vaporizer for vaporizing the substance, and second setting means provided upstream of the vaporizer for setting a desired amount of gas different from the raw material introduced into the vaporizer to a desired amount,
A plate-shaped member disposed in the vaporizer, the plate-shaped member having an opening for introducing a mixed gas of the vaporized raw material and the gas into a reaction chamber, and an injection unit for ejecting the raw material as droplets into the vaporizer. And a heating element for keeping the temperature inside the vaporizer constant, which is provided on the plate-shaped member. 2. The chemical vapor deposition apparatus according to claim 1 , wherein a plurality of the plate-shaped members are provided, and at least one of the plate-shaped members is provided with the heating element. 3. The chemical vapor deposition apparatus according to claim 1 , wherein the plate-shaped member is further provided with a temperature sensor. 4. The chemical vapor deposition apparatus according to claim 1 , wherein the plate-shaped member is provided with a plurality of the openings. Wherein said plate-like member is provided with a plurality, of claim 1, wherein a plurality of apertures having different sizes for each the member in the plate members are provided Chemical vapor deposition equipment. 6. A reaction chamber, an exhaust means for exhausting the reaction chamber, and a substrate holding means for holding a substrate in the reaction chamber,
In a chemical vapor deposition method in which a thin film is deposited on the substrate using an apparatus having an introducing means for introducing a raw material gas into the reaction chamber, a raw material is measured in a liquid state, and then a droplet is deposited in a vaporizer. As a raw material, and after measuring a gas different from the raw material, it is fed into the vaporizer, and the liquid raw material in the vaporizer is contacted with a heated plate-shaped member to be vaporized and A chemical vapor deposition method characterized by mixing with a gas and introducing the mixed gas in the vaporizer into the reaction chamber through an opening provided in the plate-shaped member. 7. The chemical vapor deposition method according to claim 6 , wherein the plate-shaped member is provided with a heating element to keep the temperature of the plate-shaped member uniform. 8. The temperature at the time of measuring the raw material is T1, the temperature of the plate member is T2, and the temperature for heating the substrate is T.
The chemical vapor deposition method according to claim 7 , wherein T1 <T2 <T3 is satisfied when 3. 9. Organic aluminum as the raw material,
The chemical vapor deposition method according to claim 7 , wherein hydrogen gas is used as the gas, and the temperature of the plate-shaped member is set in a range of 60 ° C to 100 ° C.