JPH07201736A - Method for cvd thin film - Google Patents

Abstract

PURPOSE:To provide a method of CVD capable of securing the evenness of a thin film for avoiding particle production in the MOCVD process. CONSTITUTION:In order to form a thin film 4 on a substrate surface 3a by CVD process, the internal pressure inside a thin film forming chamber 5 is set up within the range of 0.1-100Torr. On the other hand, the relations between the radius (a)(cm) of a single tube member 6, the Reynolds number Re in the number 6 of a material gas, the vertical length L(cm) from the substrate surface 3a to the aperture end 60 of the member 6, the diameter R(cm) of a substrate holder 8, the diameter D(cm) of the member 6 are to be sustained as L=alphaR, D=betaR (where alpha=0.9-1.2, beta = not exceeding 0.03 when Reynolds number does not exceed 1000 but not exceeding 0.05 when Reynolds number exceeds 1000) for the thin film formation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate holding base having a substantially disk-shaped substrate holding base arranged in a thin film forming chamber in which the pressure can be reduced, and a single circular pipe member opening in an upper space of the substrate holding base. The present invention relates to a CVD thin film forming method in which a raw material gas is supplied onto a substrate arranged above and a thin film is formed on the surface of the substrate by a chemical vapor deposition method.

[0002]

2. Description of the Related Art When a thin film or a thick film having a uniform film thickness is obtained in a film formation by a CVD method using a gaseous substance as a raw material,
It has been attempted to obtain a uniform film by supplying a source gas from the upper portion or the side wall of the thin film forming chamber and further rotating a substrate holder provided in the thin film forming chamber.
In order to prevent particles from adhering and mixing, the substrate on which the film is to be formed is perpendicular to the upper lid of the thin film forming chamber (which is arranged substantially in the vertical direction), or particles fall onto the film forming surface. Assuming that the film formation surface is facing vertically downward, it is not only the normal pressure CVD device but also the reduced pressure C
It is also used in VD devices. By these raw material gas blowing methods, in addition to the above-mentioned uniform film formation and the purpose of preventing particles, the purpose is to improve the processing capacity and ease of maintenance, and to enable film formation on a large-diameter substrate. In the case of considering a gaseous substance as a raw material,
Good results have been reported.

[0003]

However, in the above-mentioned prior art, organometallic compounds have recently been used in the raw material system, and since they have a high boiling point, they are condensed even if they are in a gaseous state if the heat retention state is bad. For example, it is difficult to form a uniform film on a substrate with a large diameter, and problems such as particles are generated, which makes it difficult to develop technology in the semiconductor field because fine particles are mixed in the film. There is. Therefore, in the MOCVD, various innovations have been made so far, a plurality of source gases are mixed, and a number of outlets are provided in the reactor depending on the type of the canister having many outlets and the type of source gas. However, the MOCVD device provided with a concentric circular gas supply pipe that blows out the raw material inside or outside and the oxidizing gas inside or outside is recognized in the previous report, but both of them are for uniform film formation and formation. Problems such as increasing the diameter of the film and causing deposition of a solid substance that causes clogging at the raw material gas outlet in a short time have not been solved.

Therefore, an object of the present invention is to ensure the uniformity of a thin film even when MOCVD is performed, and to prevent the generation of particles.
To obtain a thin film forming method.

[0005]

To achieve this object, the characteristic means of the CVD thin film forming method according to the present invention is that when the internal pressure in the thin film forming chamber is set to 0.1 to 100 Torr, Reynolds of raw material gas flow defined by radius a (cm), flow velocity V (cm / min) of raw material gas in a single circular pipe member, and kinematic viscosity coefficient ν (cm ² / min) of raw material gas Number Re (Re = aV / ν), vertical separation distance L (cm) from the substrate surface to the open end of the single circular tube member, substrate holding table diameter R (cm), single circular tube member diameter The relationship with D (cm) is as follows: L = αR D = βR where α is 0.9 to 1.2 β is 0 .. when the Reynolds number Re is 1000 or less.
When the film thickness is 03 or less and more than 1000, the film formation is performed while maintaining the film thickness at 0.05 or less to solve the above problem. The action and effect are as follows.

[0006]

In other words, in the CVD thin film forming method of the present application, the raw material gas is supplied from the single circular pipe member toward the substrate holder, and the raw material is sufficiently mixed in the single circular pipe member. It is supplied in the state, and it is possible to perform uniform film formation without mixing particles. Here, when the film forming pressure is in the range of 0.1 Torr to 100 Torr, as described later, it does not depend on the inner diameter and the depth (height) of the thin film forming chamber and the substrate is held to form a uniform film. It is important to be determined by the size of the table, the distance from the central part of the substrate holding table to the opening end of the raw material gas supply passage, the gas flow velocity and the diameter of the raw material gas supply passage. And
Regarding α, if α is selected to be smaller than 0.9, the reaction product is deposited at the open end of the single circular pipe member to generate particles, which causes the clogging of this member. Therefore, the film formation area becomes narrow and the film thickness distribution becomes poor. On the other hand, when α is larger than 1.2, the film formation rate becomes slow, and the product may adhere to the inner wall of the thin film forming chamber.
In addition, it is necessary to increase the equipment size and evacuation time, which increases the initial running cost.
On the other hand, with respect to β, by selecting β as described above, the raw material gas diffused from the opening end of the single circular pipe member is sufficiently supported on the substrate holder which is considered to be a substantially disc shape. The source gas can be diffused to cover. Comparing the present invention and the conventionally proposed tip-expanding type gyro type as shown in FIG. 3 and FIG. 4, in the latter type, due to the convection of the raw material gas in the gyro, As a result of film formation or convection, the powder grows into a powder, and the powder falls during film formation, causing particles and the like in the film, which is a problem. Furthermore, when providing the number of metal pipes according to the type of raw material gas, it is necessary to strictly control the raw material gas feed rate for each pipe, and the larger the diameter of the blown gas, the lighter the density of the film formation part. And other problems occur.

[0007]

EFFECTS OF THE INVENTION By using the CVD thin film forming method according to the present invention, maintenance is easy, a uniform film having a uniform film thickness can be formed, and a film can be formed without generating particles. Further, since no complicated reaction material supply pipe or rotation mechanism is provided in the thin film forming chamber, there is an advantage that an inexpensive CVD apparatus can be constructed. Therefore, with this method
Not only is it possible to manufacture films that are progressing toward a large diameter of 8 inφ, such as storage memory suitable for SI, but also applicable to objects such as semiconductor lasers where film thickness control is strict.
Especially for the synthesis of metal compounds of ternary system or higher, which requires a large diameter for next-generation materials and uniform mixing of multi-component source gases, no special rotation mechanism is required The present invention is very useful because it is simple and the device design cost is low.

Further, if a laser beam irradiating means is provided so that the film-forming energy can be supplied also from the laser beam, the film-forming can be carried out at a lower temperature than in the case of using only thermal energy.

[0009]

EXAMPLES In explaining the CVD thin film forming method of the present application, first, the structure of the CVD thin film forming apparatus 1 used for film formation will be described. What is shown in FIG. 1 is, for example, SiN.
An apparatus 100 used for binary film formation that does not require an oxidizing gas such as (silicon nitride) is shown in FIG. 2, and a ternary perovskite compound (PZT thin film) that requires an oxidizing gas is shown in FIG.
The structure of the apparatus 101 used when depositing the film is shown.

The CVD thin film forming apparatus 1 is a so-called laser CV.
D thin film forming apparatus for decomposing / exciting a raw material gas and forming a film by thermal energy supplied by a heating element and energy supplied by a laser beam 2. Laser CVD thin film forming apparatus 1 having such a configuration
Since the thin film can be formed at a lower temperature than the conventional simple CVD thin film forming apparatus, it has an advantage that the substrate 3 and the like are less thermally damaged and the thin film 4 can be formed favorably. Below, semiconductors (IC, LSI
Etc.) A case where the thin film 4 is formed on the substrate 3 will be described as an example. Here, the film thickness of the thin film 4 is in the range of about 50 angstrom to 5 μm.
When the thin film 4 having a good step coverage is formed on the substrate 3 by cutting the uneven pattern, the film can be formed uniformly within the standard deviation of 3%.

The CVD thin film forming apparatus 1 is provided with a thin film forming chamber 5 (made of stainless steel or aluminum) whose internal pressure can be adjusted, and a raw material gas supply path to which a raw material gas g1 is supplied and a film forming process. A gas discharge path 7 through which the gas g2 is discharged, and a substantially disk-shaped substrate holding table 8 on which the substrate 3 to be a thin film is placed is provided in the center of the thin film forming chamber 5. There is. Further, a metal pipe, which is a single circular pipe member 6 as a raw material gas supply passage, is provided in the upper space of the substrate holding table 8 which is arranged substantially horizontally. The vertical separation distance from the substrate surface to the open end portion 60 of the single circular pipe member 6 is L (cm), the diameter of the substrate holding table 8 is R (cm), and the diameter of the single circular pipe member 6 (inner diameter).
Is D (cm), the device is configured so that the relationship between the three parties can be maintained as follows. L = αR D = βR where α is 0.9 to 1.2 β is the radius a (cm) of the single circular pipe member 6 and the flow rate V (cm / min) of the source gas in the single circular pipe member. ) And the kinematic viscosity ν (cm ² / min) of the raw material gas, the Reynolds number Re of the raw material gas flow is defined as Re = aV / ν. Is 0.03 or less when turbulence is greater than 1000, and 0.
It should be 05 or less. That is, the CVD thin film forming apparatus 1 is configured such that the opening end portion 6 of the single circular pipe member 6 is opened from the surface of the substrate holder according to the diameter of the substrate holder.
The vertical separation distance L up to 0 and the pipe diameter D of the single circular pipe member 6 can be changed.

The single circular pipe member 6 is provided with a heat retaining means 9, and the temperature of the raw material gas supply path is higher than the vaporization temperature of the raw material gas and higher than the thermal decomposition temperature of the raw material gas in the absence of oxygen. Keep at a low temperature. On the other hand, the substrate holding table 8 is provided with heating means such as a ceramic heater 10. Further, a laser light irradiation window 11 for introducing a laser light 2 for exciting the mixed gas g3 on the substrate 3 into the thin film forming chamber is provided, and an excimer laser 12 as a laser light irradiation means for oscillating the laser light 2 is provided. Are provided on the side of the device 1. Further, the laser beam 2 is applied to the thin film forming chamber 6
A laser light exit window 13 that is led out is provided.

An outline of the equipment requirements is itemized below. Substrate size for film formation 8 inches or less Substrate heating Maximum 700 ° C Ultimate pressure 10 ^-7 Torr Light source Excimer laser

Further, since the apparatus 101 shown in FIG. 2 requires oxygen or ozone which is an oxidizing gas necessary for film formation, it is provided with an oxidizing gas supply passage 102 as an oxidizing gas supply means. A mixing chamber 103 is provided on the base end side of the single circular pipe member 6 described above.

The above is the outline of the apparatus 1, and the usage state of the apparatus 1 will be described below. The vicinity of the substrate is heated by a ceramic heater 10 provided on the substrate holder 8 and is maintained in a temperature range of about 400 ° C.
1 (or raw material gas and oxidizing gas) is supplied. At this time, the ceramic heater 10 and the excimer laser 12 are always activated. The supplied source gas g1 is diffused and supplied to the upper region of the substrate, and far infrared rays are emitted from the substrate holding table 8 toward the source gas g1 described above. That is, the source gas g1 receives energy from the far infrared rays and the laser light 2 described above, is decomposed and excited, and grows as a thin film on the substrate 3. Now, the outline of the film formation is as described above. At the time of film formation, the internal pressure in the thin film forming chamber 5 is 0.1 to 100.
The radius a (cm) of the single circular pipe member 6 which is set to Torr and constitutes the raw material gas supply path, the flow velocity V (cm / min) of the raw material gas in the single circular pipe member 6, and the movement of the raw material gas. Reynolds number Re (Re = aV / ν) of the raw material gas flow defined with the viscosity coefficient ν (cm ² / min) and the vertical separation distance from the substrate surface to the opening end of the single circular tube member 6. Is L (cm), the diameter of the substrate holder 8 is R (cm), and the diameter of the single circular tube member 6 is D (cm). L = αR D = βR where α is 0.9 to 1.2 β is 0.03 or less when the Reynolds number Re is 1000 or less and is 0.03 or less when the turbulent flow is more than 1000.
5 or less. When the film is formed under such conditions, it is possible to form the film with high uniformity while avoiding the generation of particles.

Hereinafter, the film forming results when the film is formed by the above method will be described together with comparative examples. Example 1 Silicon Nitride (SiN) Thin Film (Using the Device Shown in FIG. 1) Since SiN is a binary metal nitride, the following two kinds of gases are adopted as raw material gases. Raw material gas Si source gas SiH ₄ (silane), Si ₂ H ₆ (disilane), SiCl ₄
(Silicon tetrachloride), etc. N source gas NH ₃ (ammonia), N ₂ H ₄ (hydrazine), N ₂ (nitrogen), etc. The film was supplied from the circular tube member 6 toward the substrate holder 8. The film forming conditions were the conditions described above. Further, other film forming conditions are shown below. Laser light intensity: 90 mJ / pulse × 100 Hz Substrate temperature: 330 ° C., Substrate (Si wafer 8 in φ) The diameter of the substrate holder is 8 in φ above which the wafer can be mounted.
Minimum length equal to or greater than φ (largely drawn for easy understanding in the drawing)
00 was used to try a comparative experiment. This water-feeding source gas supply nozzle 600 has a plurality of small holes 601 at its tip.
And a small hole 601.
Is an opening in the vertical direction in the figure, and the total opening area of the plurality of small holes 601 is set to be substantially the same as the opening area of the single circular pipe member 6. Further, in forming the film, the film forming conditions were the same as those of the comparative example.

The comparison results are shown in Table 1. What is shown in the upper row is the result of this application (shown by 6 mmφ in Table 1), and what is shown in the lower row (shown by 120 mmφ in Table 1)
Is the result of the feedstock gas supply nozzle 600. Further, in the examples of 6 mmφ and 120 mmφ respectively, when the flow rate ratio of the raw material gas is the same, the upper result is that the separation distance between the substrate holding table 8 and the nozzle is set to 20 cm,
The lower one shows the one set to 4 cm.

[0018]

[Table 1]

As a result, when the source gas consisting of the single circular pipe member 6 is supplied under the above conditions as in the present application, the semiconductor DRA
It has a uniform film thickness distribution that satisfies the specifications of the M capacitor, etc., and the material distribution gas supply nozzle 600 of the watering can type has a film thickness distribution of 10% or more even in the optimum state.
When the repeated experiment was performed three times or more, there was radiant heat from the substrate holding table 8 and a film was formed in the watering can 602, and the film and fine powder dropped with repetition, and the presence of particles was recognized in the thin film.

Example 2 Lead-zirconia-titanium Thin film of ternary perovskite compound (PZT thin film) containing metal oxide (using the apparatus shown in FIG. 2) Since an oxidizing gas is required, the oxidizing gas (O ₂ or ozone-oxygen, or a gas containing atomic oxygen) was supplied from the above-mentioned oxidizing gas supply path 102 to form a film. In this case, the three types of gas are the premix chamber 103
Mixed in. Further, for the purpose of comparison, a comparative study was performed using the above-mentioned source-water supply nozzle 600 of the watering can type.
The comparison results are shown in Table 2. What is shown in the upper stage is the result of the present application (shown by 10 mmφ in Table 2), and what is shown in the lower stage (shown by 24 mmφ in Table 2) is the result of the scallop type raw material gas supply nozzle 600.

Main film forming conditions: substrate temperature: 450 ° C., reactor pressure: 2 Torr source gas: Pb (DPM) ² , Zr (Ot-C ₄ H ₉ ) ₄ , Ti
(O-i-C ₃ H ₇ ) ₄ substrate: 5 in φ Si wafer (n-type low resistance) Pt (100) alignment film / Si wafer The substrate holder is the same as that used in the 8 in φ wafer.

[0022]

[Table 2]

As a result, when the source gas consisting of the single circular tube member 6 of the present application was supplied under the above-mentioned conditions (only those shown in the lower part of the section of 10 mmφ in Table 2 satisfy the above-mentioned film forming conditions), the semiconductor DRAM capacitor It has a uniform film thickness distribution that meets specifications such as
In No. 00, the film thickness distribution is 10% or more even in the optimum state, and when the repeated experiment is performed three times or more, the substrate holding table 8
There was also radiant heat from the film, and a film was formed in the watering can, and the film and powdery substances dropped with repetition, and generation of particles was observed.

Further, when the film formation is carried out under the film formation conditions in the range described in the means for solving the above problems of the present application, the film formation should be such that particles are not generated or mixed and the film uniformity is 10% or less. I was able to. As a standard of film thickness uniformity, after forming a film on a substrate of 5 in φ to 8 in φ, multi-point film thickness measurement is performed on the entire surface of the substrate with an automatic ellipsometer (automatic ellipsometer), and its standard deviation Was used as the evaluation standard for the uniformity of the film thickness. Therefore, the inner diameter of the single circular tube member 6 should be such that the pressure inside the reactor is from 0.1 Torr to 100 Tor.
Within the range of rr, regardless of the inner diameter and the depth (height) of the thin film forming chamber 5, the above uniform film has the size of the substrate holder and the opening end 60 of the single circular tube member 6 from the substrate central portion. It can be said that good film formation can be performed when the relationship is satisfied by the distance, the gas flow rate, and the diameter of the raw material gas supply path, and the relationship satisfies the above conditions.

[Other Embodiment] Another embodiment of the present application will be described below. (A) In the above embodiment, an example of a Si substrate was shown, but this is a metal (M: metal element), metal oxide (M _x O _y ) (X = 1 to 3, Y = 1 to 7), multi-component metal composite oxide (M ₁ , M ₂ , M ₃ , O _y (Y = 1 to 7)),
Furthermore, the method of the present invention can be applied to a substrate made of one or more of metal nitride, metal boride, and metal carbide such as silicon, alkali glass, quartz glass, and gallium arsenide. Furthermore, the size of the substrate is 2 inches
Can be adapted to φ to 8 inφ. Furthermore, even a substrate with a rectangular cross section can be regarded as a disc equivalent product.
It can be applied to an in-square or more and up to 8 in-square. (B) In the above embodiment, the example in which the substrate holding table is horizontally arranged with respect to the vertically arranged source gas supply path has been described. However, in the CVD thin film forming apparatus of the present application which is normally used at 0.1 Torr to 100 Torr, Even if the substrate holder is tilted in the range of 50 ° from the horizontal direction, the film forming performance does not change significantly, and the film formation can be favorably performed by satisfying the above film forming conditions. However, the center of the substrate holding table needs to be directly under the source gas supply path. (C) As the metal pipe forming the raw material gas supply passage, a single metal pipe made of aluminum, stainless steel, copper, tantalum, or the like can be used. (D) Further, the thin film to be formed may be a binary or ternary metal oxide or metal nitride thin film. (E) As the reaction substance, not only a gaseous substance but also a liquid substance or a solid substance in the starting state can be used.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a laser CVD thin film forming apparatus of the present application.

FIG. 2 is a laser CV of the present application equipped with an oxidizing gas supply system.
Diagram showing the configuration of the D thin film forming apparatus

FIG. 3 is a diagram showing a configuration of a raw material gas supply nozzle having an open end surface.

FIG. 4 is a view showing a configuration of a raw material gas supply nozzle of an open end face widening type having a large number of small holes.

[Explanation of symbols]

 2 laser light 3 substrate 3a substrate surface 5 thin film forming chamber 6 single circular tube member 8 substrate holder 12 laser light irradiation means 60 opening end

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toru Yanagisawa, Tohru Yanagisawa 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd. Incorporated Kansai Research Institute of Technology (72) Inventor Takashi Kobayashi 17 Nakadoji-Minami-cho, Shimogyo-ku, Kyoto, Kyoto Prefecture Incorporated Kansai Research Institute of New Technology

Claims (2)

[Claims] 1. A single circular pipe member having a substantially disk-shaped substrate holder (8) arranged in a thin film forming chamber (5) capable of depressurizing the inside, and opening to an upper space of the substrate holder (8). From (6),
A CVD thin film forming method for forming a thin film (4) on the substrate surface (3a) by chemical vapor deposition by supplying a source gas onto a substrate (3) arranged on the substrate holder (8). And the internal pressure in the thin film forming chamber (5) is 0.1 to 100 Torr.
r, the radius a (cm) of the single circular pipe member (6), the flow rate V (cm / min) of the raw material gas in the single circular pipe member (6), and the raw material gas The Reynolds number Re (Re = aV / ν) of the raw material gas flow defined between the kinematic viscosity ν (cm ² / min) and the single circular tube member (6) from the substrate surface (3a). The relationship between the vertical separation distance L (cm) to the opening end (60), the diameter R (cm) of the substrate holder (8), and the diameter D (cm) of the single circular tube member (6) is as follows. Relationship L = αR D = βR where α is 0.9 to 1.2 β is 0 .. when the Reynolds number Re is 1000 or less.
A CVD thin film forming method in which a film is formed by maintaining the film thickness at 03 or less and at 1000 or more and at 0.05 or less. 2. The thin film forming chamber (5) is provided with a laser light irradiating means (12) for irradiating a space above the substrate on which the thin film is formed with a laser light (2), and energy for thin film formation is supplied to the laser. The method for forming a CVD thin film according to claim 1, wherein the film is formed by supplying also from light (2).