JP2645215B2 - Thin film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus applied to the manufacture of semiconductor devices such as VLSI devices.

[0002]

2. Description of the Related Art Generally, methods commonly used for forming a thin film on a substrate to be processed such as a semiconductor are roughly classified into chemical vapor deposition (CVD) and physical vapor deposition (CVD). PVD; Physical Vavor Deposition).

[0003] Here, the CVD method is a method of forming a thin film on a substrate by causing a chemical reaction on the substrate surface or in a gas phase, and is used for forming an insulating film such as a silicon oxide film or a silicon nitride film. It is sometimes used. Also, PVD
The method forms a thin film by colliding deposited particles generated in a gas phase with a substrate, and is often used mainly for forming a metal film or the like.

On the other hand, in the recent manufacture of VLSI devices, a technique of depositing a film in a groove having a high aspect ratio (depth / width is 1 or more) provided in a substrate to be processed in order to achieve high integration. It is becoming mandatory.

However, as shown in FIG. 18, a conventional plasma CVD method (for example, JL Vossen & W. Kern; Th)
Deposition species (52) generated in the gas phase are deposited in grooves (51) having a high aspect ratio formed on a substrate (50) to be processed, such as silicon (Si), by using Film Processes; Academic Press, 1978). When the insulating film (53) is formed in this way, the following problem occurs. In other words, the deposited species is formed in the groove (5
While the deposition progresses remarkably at the corner (54) of 1), it becomes difficult for the deposition species to enter the bottom (55) of the groove (51), and as the deposition proceeds further, a cavity is formed in the groove (51). (56) occurred, or the step coverage characteristics on the substrate surface deteriorated.

As a method for solving the above problem, a technique called bias sputtering, which is one of the PVD methods, is used (for example, T. Mogami, M. Morimoto & H. Okabay).
ashi ； Extended Abstracts 16th Conf.Solid State Dev
ices & Materials, Kobe, 1984, p. 43). In this method, an insulating film such as a silicon oxide film is formed while physically sputtering the substrate surface with ions such as Ar. According to this method, the above-described deposition of the corners (54) in FIG. 18 is less likely to be caused by the sputtering, and the deposition in the flat portion proceeds. Therefore, problems such as formation of the cavity (56) and step coverage characteristics are improved as compared with the above-mentioned CVD method.

However, since the deposited species in the gaseous phase obliquely enter the groove, it is still difficult to satisfactorily fill the groove with the aspect ratio of 1 or more. In addition, since this method uses a competitive reaction between removal and deposition of the deposited film by physical sputtering, the net deposition rate is low, and the productivity is extremely poor. Further, since the treatment is performed in plasma, there is a problem that irradiation damage cannot be avoided.

Further, recently, an ECR bias sputtering method for reducing the component of oblique incidence into the seed groove is used (for example, H. Oikawa; SEMI TECHNOLOGY SYM, 1986, E3-1).
Although the problem of oblique incidence of the above-described deposited species into the groove is reduced, the problem has not yet been solved, and a good thin film can be formed on the groove with a high aspect ratio. There was a limit to doing.

In addition to the method described above, for example, TEO
Pyrolysis of S (RDRung, T. Momose &Nagakubo; IEDM.Te
ch. Dig. 1982, p. 237) has been proposed to form a silicon oxide film. According to this method, cavities are unlikely to be formed as shown in FIG. 19A due to the large surface mobility of the deposited species, and excellent step coverage characteristics can be obtained. However, when the oxide film (53a) embedded in the premises is cleaned by, for example, a diluted HF solution by this method, as shown in FIG. 19B, the oxide film (53a) at the center (57) of the groove is formed.
At present, the removal speed of a) is abnormally high, and eventually, the burying flattening cannot be realized. It is considered that this is because the strain between the oxide films grown from both sides of the trench wall remains near the center. Even in the method of forming a thin film in a conformable manner, it is extremely difficult to embed a groove having a high aspect ratio.

[0010] Further, in FIG.
After an oxide film containing an impurity is formed as a solid-phase diffusion source by a method or the like, heat treatment may be performed to diffuse the impurity around the groove of the substrate. However, in this method, the oxide film formed on the side wall of the trench and the oxide film on the flat portion actually have a problem that the former has a lower impurity concentration and a desired specific resistance cannot be obtained. .

[0011]

According to the present invention, when a thin film is formed in a groove having a high aspect ratio formed on a substrate to be processed such as a semiconductor described above, a cavity is formed inside the groove. Another object of the present invention is to solve the conventional problems, such as poor step coverage characteristics on the substrate surface or irradiation damage to the substrate. That is, an object of the present invention is to provide a thin film forming apparatus which can satisfactorily embed a thin film of an insulator, a semiconductor, a metal or the like even in a groove having a high aspect ratio.

[0012]

SUMMARY OF THE INVENTION In the present invention, a substrate is formed so that a deposited species in a vapor phase forming a thin film can be more stably present on the surface of a substrate to be treated than floating in the vapor phase. Provided is a thin film forming apparatus in which the temperature is controlled to be equal to or lower than the boiling point of the deposition species due to the decrease in the gas phase pressure.

That is, the present invention provides a reaction vessel, a sample table provided in the reaction vessel, on which a substrate to be processed is mounted, and a step of exciting a first reactive gas in a region different from the reaction vessel. means and, means for introducing a different second reactive gas and the gas and the first reactive gas which is at least the excitation in the reaction vessel, a first reactive gas that the excitation for
During the reaction generated by the reaction of the gas and the second reactive gas
Phase diagram in which the partial pressure of the intermediate product indicates the phase of this reaction intermediate
So that the pressure is at or above the triple point in
Means for evacuating, and controlling the temperature of the substrate to be treated during the reaction.
Above the melting point of the reaction intermediate under partial pressure of the intermediate product
A first temperature control means for controlling the temperature to be equal to or lower than the boiling point; and a second temperature for controlling a portion of the reaction vessel other than the sample stage so that the temperature of the portion becomes equal to or higher than the boiling point of the reaction intermediate product. A thin film forming apparatus comprising: a temperature control unit.

In the present invention, the following embodiments are preferred.

That is, it is preferable that the first reactive gas and the second reactive gas are introduced into the container as a mixed gas. The thin film forming apparatus according to claim 1.

Preferably, the first temperature control means is provided on a sample stage on which the substrate to be processed is mounted.

Further, it is preferable that a means for heating the substrate on which the thin film is formed be heated to room temperature or higher.

Further, it is preferable that the means for heating the substrate is located in a different region from the reaction vessel.

Preferably, the means for heating the substrate is a means for instantaneously heating.

Further, the reaction vessel may include a region for transferring the substrate to be processed, and this region may be configured to be evacuated or to be capable of introducing an inert gas at atmospheric pressure or higher. preferable.

Further, it is preferable to use heat, light, electron beam, or electric discharge as means for exciting the first reactive gas.

It is preferable that a means for irradiating the substrate to be treated with charged particles or light is provided.

It is preferable that the apparatus further comprises means for vibrating the substrate to be processed or the surface of the substrate to be processed.

[0024]

The operation of forming a thin film according to the present invention will be described with reference to FIG.

In FIG. 1A, the deposited species (32) that has entered in a high-aspect ratio groove (31) formed in a substrate (30) to be processed such as a semiconductor in a gaseous state is a deposited species (3).
When the substrate to be processed whose temperature is controlled to be equal to or lower than the boiling point under the gas phase pressure of 2) is touched, it liquefies and adheres to the surface of the substrate.
(33) is a thin film formed in the groove (31) by the deposition species (32).

When this is further continued, as shown in FIG. 1 (b), the thin film (33a) is piled up in the groove (31).
Are formed so as to be embedded. And the groove (3
Continued after 1) was completely embedded, the groove (3)
A thin film (33b) on top of 1) and on the surface of the substrate (30)
Is formed satisfactorily.

To explain this phenomenon, three phases (a gas phase, a liquid phase,
FIG. 20 shows the state of the solid phase) using temperature and pressure as parameters.
Shown in As the temperature decreases, the deposited species composed of the above-described reactive gas and the like changes from the state of gas phase A in the figure to the state of liquid phase B at a point beyond the curve (curve) in the figure. When the temperature condition is further reduced, the state of the solid phase C is changed from the state of the gas phase A to a point beyond the curve (curve) in the figure. In this tendency, the transition from the gas phase A to the liquid phase B or the solid phase C becomes more remarkable under the condition of higher pressure.

For example, assuming that the reactive gas under the condition of the pressure P ₀ is in the state of the gas phase A, when the temperature is lowered to the temperature condition t ₀ or lower, the gas crosses the boundary curve between the gas phase and the liquid phase and becomes the liquid phase. .

The temperature at which the gas phase A transitions from the state of the gaseous phase A to the other phase under a certain pressure at a certain pressure is herein referred to as the boiling point at the pressure.

That is, the present invention relates to
The inventor of the present invention has conducted intensive studies on whether the temperature dependence of the phase state can be applied to the filling of trenches in semiconductor manufacturing, and succeeded in realizing the results.

When only one kind of gas is used, the substrate temperature is set to be lower than the gas boiling point.

As described above, according to the present invention, excellent planarization can be achieved after satisfactorily filling a groove having a high aspect ratio at a low temperature, which is optimal for the manufacture of an VLSI.

The thin film formed in the present invention is any one of an insulating film, a semiconductor film, a polymer film, and a metal film.

Further, it is preferable to use a gas containing at least oxygen, nitrogen, hydrogen or a halogen element as the first reactive gas.

Here, argon (A) is used as the first reactive gas.
r) and an inert gas such as helium (He) may be mixed.

Further, a gas containing at least one element from Group 2 to Group 6 of the periodic table is used as the second reactive gas, and an oxide or nitride of the element is formed on the substrate to be processed. It is preferable to form an element, a hydride, a simple substance of the element, or a compound of the element.

Further, as the second reactive gas, an organic compound of metal or semiconductor, a halogen compound, a carborne compound, or a mixed gas thereof may be used.

Further, a gas containing at least carbon and hydrogen may be used as the second reactive gas.

Further, an organic silane may be used as the second reactive gas.

Further, an n-type impurity such as arsenic (As) or phosphorus (P) or a P-type impurity such as boron (B) is added to the first reactive gas or the second reactive gas to be processed. An insulating film may be deposited thereon.

Further, it is preferable that a mask is formed on the substrate to be processed.

Further, it is preferable to perform a heat treatment after the deposition of the insulating film.

This heating is preferably instantaneous heating.

Further, after forming the thin film, a first reactive gas,
Alternatively, it is preferable to perform the heat treatment while flowing the active species formed from the first reactive gas.

Further, as the second reactive gas, methylsilane, methoxylan, ethoxysilane, propoxysilane,
It is preferable to use an organic silane such as butoxysilane, hexamethyldisiloxane, or methylsilanol.

Further, the pressure in the reaction vessel is monitored, and the pressure is set to a pressure equal to or higher than the pressure giving the triple point in the phase diagram of the reaction product of the active species of oxygen and the second reactive gas or the second reactive gas. It is preferable to provide a means for controlling

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A thin film forming apparatus according to the present invention will be described. That is, FIG. 2 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention used in this embodiment. This device has the following configuration.

The substrate to be processed (3) placed on the sample holder (2) is accommodated in the reaction vessel (1). The first reactive gas X is passed through the gas introduction pipes (4) and (5), respectively.
The active species of (6) and the second reactive gas Y (7) are introduced and exhausted through an exhaust pipe (8) connected to an exhaust system (not shown). . here,
The flow rates of the first and second reactive gases are adjusted by a mass flow controller (not shown). The activation of the first reactive gas X (6) is performed in a microwave discharge section (9) connected to the gas introduction pipe (4). Here, the gas introduction pipe (4) used was made of quartz. Microwave power is supplied from a microwave power supply (10) to the discharge unit (9) via a waveguide (11). The activation of the reactive gas X (6) is performed by plasma in this embodiment, but may be performed by thermal excitation, light excitation, electron beam excitation, or the like. The pressure in the container (1) is set by changing the conductance of a valve (not shown), and is measured and controlled by a diaphragm gauge (not shown).

In the holder (2), a cooling means (12) for cooling the substrate to be processed is provided, and if necessary, a heating means (13) may be provided. The substrate temperature is controlled by the means. That is, these means respectively monitor the temperature of the substrate (3) to be processed, and set the temperature to a predetermined value, that is, the active species generated from the first reactive gas, the second reactive gas, or these. It is connected to a control system (not shown) for setting the temperature below the boiling point of the reaction product. Here, the cooling means (12) is such that nitrogen gas passed through liquid nitrogen is transferred to the holder (2) via a cooling pipe. Here, the control of the cooling means (12) was performed by adjusting the flow rate of the nitrogen gas with a needle valve provided in the cooling pipe. Although a heater is used as the heating means (13), the cooling and heating means are not limited to those described above, but may be any as long as the temperature can be set to the predetermined value. The substrate to be processed is electrostatically fixed to the sample stage so as to obtain good thermal contact with the sample holder.

Further, the regions other than the substrate to be processed of the reaction vessel (1) and the sample holder (2) for controlling the temperature of the substrate to be processed are designed so as to maintain the cleanliness inside the reaction vessel (1). For example, a structure may be employed in which a heater (14) for flowing an electric current is wound around the wall of the container (1).

Further, as the thin film forming apparatus according to the present invention, another embodiment apparatus shown in FIGS. 3 and 4 can be used. The device shown in FIG. 3 has substantially the same configuration as that of FIG. 2, and the same parts as those of FIG. 2 are denoted by the same reference numerals. This embodiment differs from the apparatus shown in FIG. 2 in that a light irradiation means (16) for irradiating a reaction vessel (1) with light (15) such as electrons, ions, or laser light on a substrate to be processed. Is provided. That is, the light irradiation means (1)
According to 6), the reactive gas can be excited by light. According to the optical excitation, it is possible to reduce the influence of damage to the substrate to be processed (3) as in the apparatus having the configuration shown in FIG.

Although not shown, the substrate to be treated (3) is taken in and out of the reaction vessel (1) through a separate chamber provided adjacent to the reaction vessel (1). An inert gas higher than the atmospheric pressure is allowed to flow. Thus, the reproducibility of the process is greatly improved by using a so-called load lock for the reaction vessel (1).

The thin-film forming apparatus of another embodiment shown in FIG. 4 has substantially the same configuration as that of the apparatus shown in FIG. 2, and the same parts as those in FIG. 2 are denoted by the same reference numerals. . This apparatus is a thin film forming apparatus capable of performing post-processing after forming a thin film. In this apparatus, after a thin film is formed on the substrate to be processed (3), the substrate (3) is transferred to the heat treatment chamber (18) via the transfer form (17) by a transfer mechanism (not shown). It has become. The substrate (2) transferred to the heat treatment chamber (18) is placed on a holder (20) provided with a heating means (19), and is subjected to heat treatment. In the heating, the substrate to be processed (3) may be irradiated with an infrared lamp (21) to instantaneously raise the substrate temperature.

By performing the above-described heat treatment, it is possible to remove residues, dusts, etc. attached to the substrate (3) to be processed, or to improve the quality of the thin film.

In the figure, (22) is a gas inlet for introducing the inert gas Z (23), and (24) is a gate valve for separating the reaction vessel (1) from the heat treatment chamber (18). .

Next, an embodiment of a method using the thin film forming apparatus according to the present invention will be described. Although any of the above-described three devices may be used as the device used in this method, description will be made here using the device shown in FIG.

In this embodiment, oxygen (O ₂ ) gas is used as the first reactive gas X, and tetramethylsilane (Si (CH ₃ )) which is an organic silane is used as the second reactive gas Y.
₄ ; TMS) is used. Here, a silicon substrate is used as a substrate to be processed, and a silicon oxide film is deposited on the silicon substrate. First, oxygen radicals (O) are generated from the O ₂ gas (6), which is the first reactive gas, by microwave discharge at 2.45 GHz in the microwave discharge unit (9).
These oxygen radicals are transported to the reaction vessel (1) through the gas introduction pipe (4). On the other hand, TMS is introduced into the reaction vessel (1) without discharging. The total pressure in the reaction vessel (1) was set at 2 Torr. A stainless steel pipe (12) is embedded in the sample holder (2), and a cooling N ₂ gas through which liquid nitrogen is passed is allowed to flow to lower the temperature of the substrate (3).

FIG. 5 shows the deposition rate of the silicon oxide film and the buried shape of the silicon trench when the substrate temperature is changed by the above-described method. Where O
₂ and TMS flow rates are 56 SCCM and 7 SCC respectively
M, and the aspect ratio of the groove is one or more, for example, 1.5.

From the figure, it can be seen that the deposition rate is maximum when the substrate temperature is -40 ° C. as shown by the curve A. Regarding the shape of the groove to be buried, as shown in FIG.
The silicon oxide film generated by the reaction of MS produces the cavity described in the prior art.

On the other hand, as the substrate temperature was lowered, preferential deposition at the corners of the groove was reduced, and at a substrate temperature of −20 ° C. or lower, the thin film could be completely embedded in the trench groove.

FIG. 6 shows that the flow ratio of O _{2 to} TMS is 2
4 shows the deposition phase and the deposition shape with respect to the substrate temperature when the value is 4. Conditions other than the flow rate ratio were the same as in the case of FIG. This figure also shows the same tendency as in FIG.
It has been found that this process is also suitable for forming an interlayer insulating film in a multilayer wiring technology, for which low-temperature flattening is increasingly required.

The present inventors have conducted further analysis in order to elucidate these phenomena and to find optimal conditions for forming a thin film in a groove. This is described below.

FIG. 7 shows a phase diagram of hexamethyldisiloxane and trimethylsilanol which can be a reaction product between tetramethylsilane (TMS), an active species of oxygen (O ₂ ) and tetramethylsilane. The flow ratio of oxygen (first reactive gas) to tetramethylsilane (second reactive gas) is 2 or more. As described in the above embodiment, when the pressure in the reaction vessel is 2 Torr, the inside of the groove can be buried when the temperature of the substrate drops around -20 ° C. From this state diagram, it can be seen that the substrate temperature is from 20 ° C. to -10.
When the pressure in the container at 0 ° C. is less than 10 Torr, the liquid involved in the deposition is assumed to be tetramethylsilane and / or hexamethyldisiloxane. It is considered that oxidation proceeds while active species are taken into the liquid layer. This can be said to be appropriate because the infrared absorption spectrum of this film matches well with the infrared absorption spectrum of the plasma-polymerized film of hexamethyldisiloxane.

As described above, when the pressure in the reaction vessel is 2 Torr, the substrate temperature is -22 ° C. or less at which hexamethyldisiloxane liquefies, and -1 at which tetramethylsilane solidifies.
It is necessary that the temperature is not lower than 00 ° C.

That is, the boiling point under a predetermined pressure is about -23 ° C. with hexamethyldicycloxane at about 2 Torr and about −75 ° C. with tetramethylsilane at a pressure of 2 Torr, and about 0 ° C. with hexamethyldisiloxane at 10 Torr.
About -60 ° C for tetramethylsilane.

Therefore, it is necessary to improve the thermal contact between the substrate to be processed and the sample holder, to make the temperature distribution of the sample uniform, to accurately measure and control the temperature, and to allow liquefaction.

Next, FIG. 8 shows changes in the pressure, deposition rate, and deposition shape in the reaction vessel. Substrate temperature is -40
° C and the flow rates of TMS and oxygen were 7 SCCM and 168 SCCM, respectively. As a result, it was found that at around 10 Torr, the deposit formed a large lump on the substrate surface and could not be buried in the trench, but it became possible to fill the trench with a decrease in pressure, and the deposition rate was increased. That is, this is because the shape of the droplet (90) adhered as a lump on the substrate is represented by the Laplace's equation when coordinates are taken as shown in FIG.

[0068]

(Equation 1) Can be represented by (91) is a substrate.
Here, the seed curvature of the curved surface in the plane of the drawing is r / Sin
φ, and the principal curvature perpendicular thereto is R. γ is the surface tension, ρ
Is the density of the liquid and _ΔPo is the pressure difference between the inside and outside of the droplet at the top. Here, the droplet (90) is rotationally symmetric and has
If the two principal curvatures are equal and b, then

[0069]

(Equation 2) When the pressure difference ΔP _o increases when the surface tension γ is equal, the radius of curvature b of the vertex decreases, and FIG.
The droplets are considered to be elongated as shown in FIG. In addition, due to the change in the pressure of the microwave discharge, the type and amount of the active species of O ₂ change, the functional units generated on the surface of the silicon substrate change, and the contact angle with hexamethyldisiloxane or tetramethylsilane changes. May change. For the above two reasons, the pressure at which liquefaction occurs,
Even in the temperature range, the pressure is preferably set to a contact angle in a range where the liquid flows into the trench, particularly an acute angle. In this embodiment, the pressure is desirably 10 Torr or less. That is, the pressure is preferably equal to or higher than the triple point pressure so that liquefaction of hexamethyldisiloxane or tetramethylsilane occurs.

Next, FIG. 11 shows changes in the deposition rate and the deposition shape with respect to the flow ratio of O ₂ and tetramethylsilane (TMS). This indicates that the deposition rate has a peak at a flow rate ratio of O ₂ / TMS at around 20. It was also found that the burying of the trench became possible when the O ₂ / TMS flow rate ratio was around 4, and when the flow rate was more than 4, the burying was performed. This is thought to be because the following reaction occurs when hexamethyldisilonsan is formed from oxygen and TMS. That is, if the reaction is 2Si (CH ₃ ) ₄ + 4O ₂ (TMS) → [Si (CH ₃ ) ₃ ] ₂ O + 2CO ₂ + 3H ₂ O (hexamethyldisiloxane), then O ₂ / TMS = 2. . Thus O ₂ when tetramethylsilane is 7SCCM is required than 14 sccm, if O ₂ / TMS flow ratio of the ideal reaction takes place is of at least 2 or more is good, practically the It turned out that it is good that it is four or more.

FIG. 12 shows the infrared absorption spectra of the deposited films when the flow ratios of O ₂ / TMS were 8 (Graph A), 24 (Graph B) and 40 (Graph C), respectively. It is. ~ 1200cm ^-1 to 1000cm ^-1
Has an absorption peak of Si-O-Si, and it was confirmed that the film was a silicon oxide film. Si—CH ₃ , Si—H, O normalized by the absorption peak of Si—O—Si
FIG. 13 shows a change in the intensity of the absorption peak of -H with respect to the O ₂ / TMS flow ratio. From this figure, it was found that the oxidation of silicon progressed as O ₂ / TMS increased.
1 to 7 correspond to 1 to 7 in FIG.

Next, the properties of the thin film formed according to the present invention were examined. For this purpose, as shown in FIG. 14, the O ₂ / TMS flow ratio of the etching rate of this deposited film with an aqueous solution of HF 6% and NH ₃ F 30% was examined. This allows O ₂
It was found that the etching rate was decreased with an increase in / TMS, and the film was further densified. In order to improve the film quality of the deposited film, the flow rate of O ₂ is relatively increased and O ₂ / TM
It has been found that it is desirable to increase the S flow rate ratio.

Further, after depositing the thin film on the substrate to be processed, the substrate to be processed was heat-treated in a reaction vessel by the following two methods.

(1) A substrate temperature of 3 in O ₂ 10 Torr
Heat treatment at 00 ° C. for 1 hour (2) Heat treatment at a substrate temperature of 300 ° C. while microwave discharging O ₂ at 2 Torr for 1 hour SiO 2 of infrared absorption spectrum of the resulting film
Si-CH ₃ , Si normalized by the absorption peak intensity of Si
FIG. 15 shows the change in the absorption intensity of -H and O-H with respect to each O ₂ / TMS flow rate ratio. Si-CH _3, O
-H bonding is (0) without annealing, (1) heat treatment,
It was found that the number decreased in the order of the heat treatment in (2), and that oxidation of silicon proceeded. Further, the bond of Si—H is represented by (1),
It was found that both of the heat treatments (2) disappeared.
As described above, in order to improve the film quality of the deposited film, the temperature of the substrate is set to at least 300 ° C. and the heat treatment of (1) or (2) is performed, whereby the oxidation of silicon can be promoted.
In particular, it can be seen that the progress of oxidation by the heat treatment (2) is remarkable.

When forming the film, ArF having a wavelength of 193 nm is used.
When the substrate surface is irradiated with an excimer laser, the liquefied layer,
Alternatively, it was experimentally confirmed that the surface of the base was activated and the burying flattened further. Therefore, it is considered that activation is caused by photons having large energy of at least 193 nm or less in wavelength. At this time, Ar
The irradiation energy of the F laser is 330 Joules / cm ² s
ec, and if the energy is equal to or more than this, the activation proceeds more. Therefore, it is considered that the activation occurs when the energy is equal to or more than 330 Joule / cm ² sec. In addition, this activation is performed by bombarding the surface of the substrate with ions, electrons, or the like, thereby increasing the surface migration of the active species into the thin film and further promoting the flattening of the embedded film.

Second Embodiment Next, a modification of the method of the first embodiment described above will be described. That is, in this embodiment, as shown in the process cross-sectional view of FIG. 16, a silicon oxide film that fills the groove of the substrate to be processed by using the second reactive gas of the first embodiment that contains impurities is used. Forming an insulating film to which impurities are added as an insulating film, and then performing a heat treatment,
The impurity is diffused into the base.

First, as shown in FIG. 16A, as in the first embodiment, a substrate (40) made of silicon or the like having a groove (41) with an aspect ratio of 1 or more is used. This is placed on a sample holder (2) in a reaction vessel (1) of the thin film forming apparatus shown in FIG. 2, for example. Here, oxygen (O ₂ ) is introduced as the first reactive gas (6), and a gas containing AsH ₃ in TMS as the second reactive gas (7) is introduced into the reaction vessel (1). To form a thin film. At this time, the substrate temperature was −50 ° C., and the pressure inside the container was 3 Torr. The state diagram in this case is almost the same as FIG.

As a result, the groove (4) shown in FIG.
In 1), a silicon oxide film (42) containing As as an impurity can be embedded. Thereafter, when the heater further applies heat (43) by a lamp to raise the temperature of the base (40), as shown in FIG.
The impurities (44), here arsenic (As), are uniformly diffused into the periphery of the groove (41). This is because impurities taken in the oxide film are uniformly distributed in the oxide film. The oxide film (42) containing the impurity (44) can be used as a so-called solid-phase diffusion source.
This is particularly effective for manufacturing a device such as M which needs to have a sufficiently large memory capacity.

Then, by further increasing the temperature of the substrate to be processed by the heating means (13) as shown in FIG. 2, impurities other than predetermined impurities, for example, heavy metal contamination such as carbon, iron, nickel, etc. Can be avoided, and a better film can be formed. (45) is an insulating film formed on the substrate to be processed.

Here, as an example of diffusing As, the second
AsH ₃ was used as an impurity to be added to the reactive gas of Example 1. However, if P (phosphorus) is to be diffused, the first or second reactive gas such as POCl ₃ , PCl ₃ , PH _3, etc. A substance which is taken into a thin film which forms P by reacting with a gas element can be used. For diffusion of B (boron), BCl ₃ , B ₂ H ₆ or the like can be used.

Third Embodiment Next, a description will be given of a third embodiment according to the method using the thin film forming apparatus of the present invention. Here, a polymer thin film using a gas containing a halogen element such as H ₂ , N ₂ or SiCl ₄ as a first reactive gas and a gas containing at least carbon and hydrogen as a second reactive gas. The method for forming the layer will be described.

Since this is basically the same as the first and second embodiments, a brief description will be given with reference to FIG.

First, as a substrate to be processed, a silicon substrate having a concave and convex shape including a groove having an aspect ratio of 1 or more was used. Then, nitrogen (N ₂ ) gas is used as the first reactive gas X (6), and N ₂
Introduce radicals. As the second reactive gas Y (7), methyl methacrylate (MMA) is introduced and exhaust is performed. The substrate temperature was cooled to −30 ° C. or less (the pressure at which MMA becomes a liquid phase at −30 ° C. is 1 Torr or more). Thereby, the surface unevenness of the substrate to be processed is
It was embedded by the PMMA film, which is a polymer of MMA, according to the same principle as that described with reference to FIG. As is well known, this PMMA film is widely used as an electron beam resist.

Fourth Embodiment A fourth embodiment according to the method using the thin film forming apparatus of the present invention is described.
An example will be described. FIG. 17 is a final step sectional view showing a state in which the source and drain electrodes and the wiring of the MOS transistor are formed by using the method of this embodiment.

That is, a gate oxide film (71) and a gate electrode (72) are formed on a substrate (70) of silicon or the like, and the source and drain regions (73) and (74) are self-aligned with respect to the gate. ) Is formed. Then, after covering the entire surface with a silicon oxide film (75) by a CVD method or the like, a part of the silicon oxide film (75) on the source, drain (73) and (74) is removed by etching or the like to obtain an aspect ratio. One or more contact holes (76) are formed.

Next, source and drain electrode wirings (77) were formed according to the present invention. Specifically, H ₂ is used as the first reactive gas, and Al (CH ₃ ) _{3 is used} as the second reactive gas.
When the temperature of the substrate (70) is set to a predetermined temperature using
The Al electrode wiring (77) was completely buried in the contact hole (76), and was formed to be ultra-flat by continuing deposition. Then, after patterning the electrode wiring (77), a silicon oxide film (7) is formed as a protective film on the entire surface.
8) was formed. The formation of this protective film (78) can also be performed according to the present invention. That is, the protection film is buried in the groove formed by the wiring (77) and the CVD oxide film (75) by the same method as shown in the first embodiment, and a flat film (78) can be formed.

Further, in this embodiment, when forming the electrode wiring (77), the substrate (70) is mechanically vibrated, so that the gas-phase stagnation layer (G) exists between the substrate (70) surface and the gas phase. Disturbing the stagnation layer)
1 to facilitate the deposition of the film. As described above, when a thin film is formed, it may be applied to the substrate itself or the gas phase, but by applying vibration, the deposition rate can be promoted, and the film quality can be improved.

FIGS. 2 to 4 show the means for giving vibration.
In the above, mechanical vibration may be transmitted to the sample holder (2) by a motor or the like, or an ultrasonic vibrator may be built in the holder (2).

Further, in this embodiment, an example has been described in which Al is used as the metal to be buried in the trench such as the contact of the MOS transistor, but another metal can be formed as appropriate. Also,
Depending on the application, not only H ₂ but also N
₂ or as the second reactive gas Al (C
H _{3) 3} as well Ti (C ₂ H _{5) 2} or the like organic metal,
Carbonyl metals such as W (CO) ₆ and Cr (CO) ₆ ,
Alternatively, a metal halide or the like can be used.

The embodiments according to the present invention have been described above. Various modifications of these embodiments will be described below.

In the first and second embodiments, a gas containing at least oxygen as a component, for example, N ₂ O or the like can be used instead of discharging O ₂ , and N ₂ or NH ₃ can be used. Accordingly, a nitride film can be formed. Further, in addition to tetramethylsilane as the second reactive gas, tetramethoxysilane, tetraethoxysilane,
Generally known organic silanes such as tetrapropoxysilane and tetrabutoxysilane and hexamethyldisiloxane,
Trimethylsilanol may be used, and an oxide film or a nitride film thereof can be formed using a gas containing at least one element included in Groups 2 to 6 of the periodic table. The substrate temperature at that time may be appropriately set to be equal to or lower than the first reactive gas active species, the second reactive gas, or the boiling point of these reaction products, depending on the type of gas used.

Further, by mixing an inert gas such as Ar or He into the first reactive gas, metastable active species having a long life of these inert gases are generated. This active species allows the active species of the first reactive gas to be carried further. As a result, the degree of freedom in device design can be increased.

By mixing a gas containing, for example, a halogen element in the first reactive gas, for example, a methyl group in tetramethylsilane is reduced, and more stable CH ₄ or CH ₃ Cl or the like is obtained. Are formed and removed, the concentration of carbon impurities in the film is reduced, and higher quality is achieved. On the other hand, the methyl group of TMS is oxidized by oxygen, and a large amount of H ₂ O is generated in the gas phase. However, when the halogen is mixed, HF or OF having a high vapor pressure is formed, and H ₂ O is removed. Is done. Therefore, H _{2 in the} film
O also prevents the incorporation of O, thereby improving the quality of the film.

In addition to the above-described thin film formation, for example, at least Si or Ge such as H ₂ as the first reactive gas and GeH ₄ , SiH ₄ , SiCl ₄ , GeCl ₄ as the second reactive gas. If a gas containing is used, Si and Ge can be deposited, respectively. As the second reactive gas, As (CH ₃ ), AsH ₃ , Ga (CH)
₃ , it is possible to deposit a III-V group compound such as GaAs by using GaH ₃ or the like, and a II-VI group compound such as InP by using a reactive gas containing In and P. .

In the method of forming a thin film described above, a so-called thin film raw material gas has been used as the second reactive gas. However, the first reactive gas and the second reactive gas are, for example, Al
The same effect was obtained by mixing like (CH ₃ ) ₄ + H ₂ and using these mixed gases as the reactive gas.

Further, in FIGS. 2 to 4, a rotating mechanism is connected to a sample holder (12) on which the substrate (3) to be mounted is mounted, and the substrate (1) is rotated at a high speed so that the substrate (1) is rotated. Alternatively, the reactive gas may be uniformly distributed.

Here, the rotation may be performed at a constant speed, but may be performed intermittently so that the gas phase does not rotate with the substrate.

With the above structure, the deposition rate can be further increased, and even if the substrate (3) to be processed such as a large-diameter silicon wafer is used, the gas inlet (4),
Variations in the deposition rate on the substrate (3) and the composition of the deposited film due to differences in the distance from (5) to the surface of the substrate (3) can be reduced. Irradiation with light such as electrons, ions, or laser light is advantageous because it compensates for non-uniformity of the beam and does not require a large-diameter beam.

Further, in FIGS. 2 to 4, a plurality of substrates to be processed may be simultaneously introduced into the reaction vessel. For example, when the reaction vessel is a rectangular parallelepiped,
The substrate to be processed may be arranged on one side, the other side may be used for taking in and out the substrate to be processed, and the other side may be used for evacuation and introduction of the first and second reactive gases. Also in this case, a uniform thin film can be formed by placing each substrate to be processed at an equal distance from the gas inlet.

As described above, the present invention can be appropriately modified without departing from the gist.

[0101]

According to the present invention, even in the case of a groove having a high aspect ratio, an insulator, a semiconductor, a metal, or the like can be buried very well without causing irradiation damage and flattening can be realized as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a view for explaining an operation of forming a thin film in a thin film forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of a thin film forming apparatus according to the present invention.

FIG. 3 is a schematic configuration diagram showing an embodiment of a thin film forming apparatus according to the present invention.

FIG. 4 is a schematic configuration diagram showing an embodiment of a thin film forming apparatus according to the present invention.

FIG. 5 is a diagram for explaining an effect of the present invention.

FIG. 6 is a diagram illustrating an effect of the present invention.

FIG. 7 is a diagram for explaining the effect of the present invention.

FIG. 8 is a diagram for explaining an effect of the present invention.

FIG. 9 is a diagram illustrating an effect of the present invention.

FIG. 10 is a diagram illustrating an effect of the present invention.

FIG. 11 is a diagram illustrating an effect of the present invention.

FIG. 12 is a diagram illustrating an effect of the present invention.

FIG. 13 is a diagram illustrating an effect of the present invention.

FIG. 14 is a diagram illustrating an effect of the present invention.

FIG. 15 is a diagram illustrating an effect of the present invention.

FIG. 16 is a sectional view showing an embodiment of a thin film forming method using the thin film forming apparatus of the present invention.

FIG. 17 is a sectional view showing an embodiment of a thin film forming method using the thin film forming apparatus of the present invention.

FIG. 18 is a view for explaining a problem of the conventional technique.

FIG. 19 is a view for explaining a problem of a conventional technique.

FIG. 20 is a view for explaining the operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction container 2 ... Sample holder 3 ... Draw processing base 6 ... First reactive gas 7 ... Second reactive gas 9 ... Discharge part 12 ... Cooling means 13 ... Heating means 15 ... Light 18 ... Heat treatment chamber 30, 41: heat treated base 31: groove 32: deposited species 33, 33a, 33b, 42: thin film 43: heat 44: impurity 70: substrate 71: gate oxide film 72: gate electrode 73, 74: source, drain 75: CVD silicon oxide Film 76: contact hole 77: source and drain electrode wiring 78: protective film

Claims (10)

(57) [Claims] 1. A reaction vessel, a sample table provided in the reaction vessel, on which a substrate to be processed is placed, and means for exciting a first reactive gas in a region different from the reaction vessel, means for introducing a second reactive gas different from the first reactive gas which is at least the excitation and the gas into the reaction vessel, a first reactive gas and the second was the excitation
Of the reaction intermediate produced by the reaction of the reactive gas
In the phase diagram where the partial pressure indicates the phase of this reaction intermediate,
A means for evacuating the vessel so that the pressure is equal to or higher than the critical pressure, and the temperature of the substrate to be treated is reduced by the reaction intermediate product.
Above the melting point and below the boiling point of the reaction intermediate under partial pressure
That the first temperature control means allowed to control a portion of the reaction vessel other than the sample stage is partial equipped with a second temperature control means for temperature control such that the boiling point or higher of the reaction intermediate products A thin film forming apparatus characterized by the above-mentioned. 2. The thin film forming apparatus according to claim 1, wherein the first reactive gas and the second reactive gas are introduced into the container as a mixed gas. 3. The thin film forming apparatus according to claim 1, wherein said first temperature control means is provided on a sample stage on which said substrate to be processed is mounted. 4. The thin film forming apparatus according to claim 1, further comprising means for heating the substrate on which the thin film has been formed to room temperature or higher. 5. The thin film forming apparatus according to claim 1, wherein the means for heating the substrate is located in a region different from the reaction vessel. 6. The thin film forming apparatus according to claim 1, wherein the means for heating the substrate is a means for instantaneously heating the substrate. 7. The reaction vessel may include a region for transferring the substrate to be processed, and the region may be evacuated or configured to be capable of introducing an inert gas at atmospheric pressure or higher. 2. The thin film forming apparatus according to claim 1, wherein: 8. The thin film forming apparatus according to claim 1, wherein heat, light, electron beam, or electric discharge is used as a means for exciting the first reactive gas. 9. The thin film forming apparatus according to claim 1, further comprising means for irradiating the substrate to be treated with charged particles or light. 10. The thin film forming apparatus according to claim 1, further comprising means for vibrating the substrate to be processed or the surface of the substrate to be processed.