JP3210794B2 - CVD thin film forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate holder having a substantially disk-like shape, which is disposed in a thin film forming chamber whose inside can be decompressed. The present invention relates to a CVD thin film forming method for forming a thin film on a substrate surface by a chemical vapor deposition method by supplying a source gas onto a substrate provided thereon.

[0002]

2. Description of the Related Art When a thin film or a thick film having a uniform film thickness is obtained by a CVD method using a gaseous substance as a raw material,
Attempts have been made to obtain a uniform film by supplying a source gas from an upper portion or a side wall of the thin film forming chamber, or by rotating a substrate holder provided in the thin film forming chamber.
Also, 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 formation chamber (substantially vertically arranged), or the particle falls on the film formation surface. Assuming that the film will be formed, the film deposition surface is oriented vertically downward.
It is also used in VD devices. By these source gas blowing methods, in addition to the above-mentioned purpose of forming a uniform film and preventing particles, there is a method that aims to improve processing capability, facilitate maintenance, and form a film on a large-diameter substrate. If gaseous substances are considered as raw materials,
Good results have been reported.

[0003]

However, in the above-mentioned prior art, organometallic compounds have recently been used as a raw material system, and since they have a high boiling point, even if they are in a gaseous state, they are condensed if the heat retention state is poor. Due to such problems, it is difficult to form a uniform film on a large-diameter substrate, and there are also problems such as particles, and fine particles are mixed into the film, making it difficult to develop technology in the semiconductor field. I have. For this purpose, various methods have been devised in MOCVD so far, and a plurality of source gases are mixed, and a number of outlets are provided in the reactor according to the type of a raw material gas having a large number of outlets. In previous reports, a conventional method and a MOCVD apparatus provided with concentric gas supply pipes for blowing raw material inside or outside and oxidizing gas inside or outside were found in the previous reports. Problems such as the increase in the diameter of the film and the deposition of a solid substance which causes blockage at the material gas outlet through short-time film formation cannot be solved.

[0004] Accordingly, an object of the present invention is to provide a CVD method capable of ensuring uniformity of a thin film and preventing generation of particles even when MOCVD is performed.
It is to obtain a thin film forming method.

[0005]

A feature of the CVD thin film forming method according to the present invention for achieving this object is that when the internal pressure in the thin film forming chamber is set at 0.1 to 100 Torr, a single circular tube member is formed. Reynolds of source gas flow defined between radius a (cm), flow rate V (cm / min) of source gas in a single tubular member, and kinematic viscosity coefficient ν (cm ² / min) of source gas The number Re (Re = aV / ν), the vertical separation distance L (cm) from the substrate surface to the opening end of the single tube member, the diameter R (cm) of the substrate holder, and the diameter of the single tube member The relationship with D (cm) is as follows: L = αR D = βR where α is 0.9 to 1.2 β is 0 if the Reynolds number Re is 1000 or less.
03 or less, if it is more than 1000, keep it at 0.05 or less and include lead-zirconia-titanium metal oxide
The above object has been achieved by forming a perovskite compound thin film. The operation and effect are as follows.

[0006]

In other words, according to the CVD thin film forming method of the present invention, the raw material gas is supplied from the single cylindrical member toward the substrate holding table, and the raw material is sufficiently mixed in the single cylindrical member. Supplied in a state, it is possible to form a uniform film without mixing of particles. Here, when the film formation pressure is in the range of 0.1 Torr to 100 Torr, as described later, regardless of the inner diameter and the depth (height) of the thin film formation chamber, the substrate is held for forming a uniform film. It is important that the size is determined by the size of the table, the distance from the center of the substrate holding table to the opening end of the source gas supply path, the gas flow rate and the diameter of the source gas supply path. And
As for α, when α is selected to be smaller than 0.9, a reaction product precipitates at the opening end of the single tubular member and particles are generated, which causes a blockage of this member. Therefore, the film formation area is reduced, and the film thickness distribution is deteriorated. On the other hand, if 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 formation chamber,
In addition, it is necessary to increase the size of the equipment and lengthen the 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 sufficiently moves the substrate holding table with respect to the substrate holding table which is regarded as having a substantially disk shape. The source gas can be diffused so as to cover. A comparison between the present invention and the conventionally proposed type of the open-end type jar, as shown in FIGS. 3 and 4, shows that in the latter case, the convection of the raw material gas in the jar causes the inner jar. As a result of convection, the film grows into a powder form, and the powder drops during the film formation, causing particles and the like in the film to occur, which is a problem. In addition, when metal pipes are provided in a number corresponding to the type of source gas, the feed rate of the source gas must be strictly controlled for each pipe, and the larger the diameter of the blowout amount, the more the density of the film-forming portion And other problems occur.

[0007]

According to the method for forming a CVD thin film according to the present invention, a uniform film having a uniform thickness and easy maintenance can be formed, and the film can be formed without generating particles. In addition, since there is no need to provide a complicated reactant supply pipe and a rotating mechanism in the thin film forming chamber, there is an advantage that a low-cost CVD apparatus can be configured. Therefore, by this method, the next-generation ultra-L
Not only is it possible to manufacture a film having a large diameter of 8 inφ such as a storage memory suitable for SI, but it can also be applied to an object whose film thickness is strictly controlled, such as a semiconductor laser.
In particular, for large-diameter materials for the next generation, and for the synthesis of ternary or higher metal compounds that require uniform mixing of multi-component source gases, no special rotating mechanism is required and the equipment shape is required. Therefore, the present invention is very useful because it is simple and the cost of device design is low.

[0008] Further, when a laser beam irradiating means is provided so that the film forming energy can be supplied also from the laser beam, the film can be formed at a lower temperature than in the case where only thermal energy is used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing a CVD thin film forming method of the present invention, first, a configuration of a CVD thin film forming apparatus 1 used for film formation will be described. FIG. 1 shows, for example, SiN
FIG. 2 shows an apparatus 100 used for binary film formation not requiring an oxidizing gas such as (silicon nitride). FIG. 2 shows a ternary perovskite compound (PZT thin film) requiring an oxidizing gas.
1 shows a configuration of an apparatus 101 used for forming a film.

The CVD thin film forming apparatus 1 is a so-called laser CV.
This is a D thin film forming apparatus for decomposing, exciting, and forming a film of a source gas 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
Is capable of forming a thin film at a lower temperature than a conventional simple CVD thin film forming apparatus, and thus has an advantage that thermal damage to the substrate 3 and the like is less likely to occur and a good thin film 4 can be formed. Below, semiconductors (IC, LSI
Etc.) A case where the thin film 4 is formed on the substrate 3 will be described by way of example. Here, the thickness of the thin film 4 is in the range of approximately 50 Å to 5 μm.
When a thin film 4 having good step coverage is formed after cutting a pattern having irregularities on the substrate 3, a uniform film having a standard deviation of 3% of the film thickness can be formed.

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. 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 on which a thin film is to be formed is mounted in the center of the thin film forming chamber 5. I have. Further, a metal pipe, which is a single circular pipe member 6 serving as a raw material gas supply path, is provided for the substrate holding table 8 which is disposed substantially horizontally, and which opens into an upper space thereof. The vertical separation distance from the substrate surface to the opening end 60 of the single tubular member 6 is L (cm), the diameter of the substrate holder 8 is R (cm), and the diameter (inner diameter) of the single tubular member 6
Is set to D (cm), the apparatus is configured so that the relationship between the three can be maintained in the following relationship. L = αR D = βR where α is 0.9 to 1.2 β is the radius a (cm) of the single tubular member 6 and the flow velocity V (cm / min) of the raw material gas in the single tubular member ) And the kinematic viscosity coefficient ν (cm ² / min) of the raw material gas, when the Reynolds number Re of the raw material gas flow is defined as Re = aV / ν, the laminar flow with a Reynolds number Re of 1000 or less At 0.03 or less, and at turbulence larger than 1000 at 0.0.
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 separated 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 tubular member 6 is provided with a heat retaining means 9 for supplying the raw material gas to the raw gas supply passage at a temperature higher than the vaporization temperature of the raw gas and lower than the thermal decomposition temperature of the raw gas in the absence of oxygen. Maintain low temperature. On the other hand, the substrate holder 8 is provided with heating means such as a ceramic heater 10. Further, a laser light irradiation window 11 through which the laser light 2 for exciting the mixed gas g3 on the substrate 3 is introduced 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 led out is provided.

The outline of the equipment requirements is listed below. Substrate size to be deposited 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 required for film formation, it has an oxidizing gas supply path 102 as 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 outline of the apparatus 1 has been described above. The use 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 holding table 8 and held in a temperature range of about 400 ° C.
1 (or a raw material gas and an oxidizing gas) are supplied. At this time, the ceramic heater 10 and the excimer laser 12 always operate. 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 aforementioned source gas g1. That is, the source gas g1 is decomposed and excited by receiving energy from the far-infrared ray and the laser beam 2, and grows on the substrate 3 as a thin film. By the way, the outline of the film formation has been described above. In the film formation, the internal pressure in the thin film formation chamber 5 is 0.1 to 100.
The pressure is set to Torr, the radius a (cm) of the single pipe member 6 forming the source gas supply path, the flow velocity V (cm / min) of the source gas in the single pipe member 6, and the movement of the source gas. Reynolds number Re (Re = aV / ν) of the source gas flow defined between the viscosity coefficient ν (cm ² / min) and the vertical separation distance from the substrate surface to the opening end of the single circular pipe member 6 L (cm), the diameter of the substrate holding table 8 is R (cm), and the diameter of the single tubular member 6 is D (cm), and the following relationship is maintained. 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 for laminar flow, and 0.0 for turbulent flow larger than 1000.
5 or less. When the film is formed under such conditions, a highly uniform film can be formed while avoiding generation of particles.

Hereinafter, the results of film formation 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 apparatus shown in FIG. 1) Since SiN is a binary metal nitride, the following two types of gases are employed as source gases. Source 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 one circular tube member 6 to the substrate holding table 8 to form a film. The film forming conditions were the same as those 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 inφ) The diameter of the substrate holder is 8 in which the above 8 in φ wafer can be mounted.
The minimum equivalent length of φ or more (largely drawn for easy understanding in the drawing) On the other hand, the raw gas supply nozzle 6 of the joule type shown in FIG.
Using 00, a comparative experiment was attempted. The rotatable source gas supply nozzle 600 has a plurality of small holes 601 at its tip.
Are provided facing the substrate 3, and each small hole 601 is provided.
Is open in the vertical direction in the figure, and the total opening area of the plurality of small holes 601 is set substantially equal to the opening area of the single circular pipe member 6. Further, in the film formation, the film formation conditions were the same as those for the comparison.

Table 1 shows the results of the comparison. The results shown in the upper row are those of the present application (shown as 6 mmφ in Table 1), and those shown in the lower row (shown as 120 mmφ in Table 1).
Shows the result of the raw material gas supply nozzle 600 of the Juro type. Further, in each of the examples of 6 mmφ and 120 mmφ, when the flow rate ratio of the source gas is the same, the upper result indicates 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 composed of the single tubular 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 and the like.
When the experiment was repeated three or more times, there was also radiant heat from the substrate holding table 8, and a film was formed in the jar 602, and the film and fine powder fell with repetition, and the presence of particles in the thin film was recognized.

Example 2 Lead-Zirconia-Titanium Ternary Perovskite Compound (PZT Thin Film) Thin Film Containing Metal Oxide Thin Film (Using Apparatus as Shown in FIG. 2) In forming the film, the same method as described above was adopted. Therefore, an oxidizing gas (a gas containing O _2, ozone-oxygen, or atomic oxygen) was supplied from the oxidizing gas supply passage 102 to form a film. In this case, three kinds of gases are supplied to the premixing chamber 103.
And mixed. Further, for comparison, a comparative study was also performed on the above-mentioned raw material gas supply nozzle 600 of the joule type.
Table 2 shows the comparison results. The result shown in the upper part is the result of the present application (indicated by 10 mmφ in Table 2), and the result shown in the lower part (indicated by 24 mmφ in Table 2) is the result of the raw material gas supply nozzle 600 of the Juro type.

Main film forming conditions Substrate temperature: 450 ° C., reactor pressure 2 Torr Source gases: Pb (DPM) ² , Zr (OtC ₄ H ₉ ) ₄ , Ti
(OiC ₃ H ₇ ) ₄ substrate: 5 inch φ Si wafer (n-type low resistance) Pt (100) alignment film / Si wafer The substrate holder is the same as that used for 8 inch φ wafer.

[0022]

[Table 2]

As a result, when the raw material gas comprising the single tubular member 6 of the present invention is supplied under the above-mentioned conditions (only those shown in the lower part of 10 mmφ in Table 2 satisfy the above-mentioned film forming conditions), the semiconductor DRAM capacitor And a uniform film thickness distribution satisfying the specifications such as the above.
00, the film thickness distribution is 10% or more even in the optimum state.
As a result, a film was formed in the jar, and the film and powder fell repeatedly, and generation of particles was observed.

Further, when the film is formed under the film forming conditions described in the means for solving the above-mentioned problems of the present application, it is possible to form a film having a uniformity of 10% or less without generation and mixing of particles. Was completed. As a standard of the film thickness uniformity, after forming a film on a substrate of 5 inφ to 8 inφ, a multipoint measurement of the film thickness is performed on the entire surface of the substrate by an automatic ellipsometer (automatic ellipsometer), and the standard deviation thereof is obtained. Was used as an evaluation standard for film thickness uniformity. Accordingly, the inner diameter of the single tubular member 6 is set so that the pressure inside the reactor is 0.1 Torr to 100 Ton.
As long as it is within the range of rr, regardless of the inner diameter and the depth (height) of the thin film forming chamber 5, the uniform film is formed by the size of the substrate holder and the opening end 60 of the single circular tube member 6 from the center of the substrate. It can be said that a good film formation can be performed when the relationship satisfies the above conditions, and is determined by the distance up to and the gas flow rate and the diameter of the source gas supply path.

Another Embodiment Hereinafter, another embodiment of the present invention will be described. (A) In the above embodiment, the example of the Si substrate is shown as the substrate. However, this is because the metal (M: metal element) and the metal oxide (M _x O _y ) (X = 1 to 3, Y = 1 to 7), multi-component metal composite oxides (M ₁ , M ₂ , M ₃ , O _y (Y = 1 to 7)),
Further, 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 2in
φ ~ 8inφ, can be applied to the extent. Furthermore, even a substrate having a rectangular cross section can be regarded as a disk equivalent product.
It is possible to adapt to the angle of not less than the in angle and up to the 8 in angle. (B) In the above-described embodiment, an example in which the substrate holding table is horizontally arranged with respect to the vertically arranged source gas supply path has been described. Even when the substrate holder is tilted within a range of 50 ° from the horizontal direction, the film forming performance does not change significantly, and the film can be formed well by satisfying the above film forming conditions. However, the center of the substrate holding table needs to be located immediately below the source gas supply path. (C) A single metal pipe made of aluminum, stainless steel, copper, tantalum, or the like can be used as the metal pipe constituting the source gas supply path. (D) Further, as the reactant, not only a gaseous reactant but also a liquid or solid reactant in a starting state can be used.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

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

FIG. 2 shows a laser CV of the present invention provided with an oxidizing gas supply system.
The figure which shows the structure of a D thin film forming apparatus

FIG. 3 is a diagram showing a configuration of a source gas supply nozzle having an open end face expanded.

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

[Explanation of symbols]

 Reference Signs List 2 laser beam 3 substrate 3a substrate surface 5 thin film formation chamber 6 single circular tube member 8 substrate holder 12 laser beam irradiation means 60 opening end

Continuing from the front page (72) Inventor Toru Yanagisawa 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Shigeru Morikawa 17 Kandoji Minamicho, Shimogyo-ku, Kyoto, Kyoto Kansai Co., Ltd. Inside the New Technology Research Institute (72) Inventor Takashi Kobayashi 17 inside the Kansai New Technology Research Center, 17 Nakadoji Minamicho, Shimogyo-ku, Kyoto, Kyoto Prefecture (56) References JP-A-4-2211078 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/205 C23C 16/48

Claims (2)

(57) [Claims] 1. A single circular tube member having a substantially disk-shaped substrate holder (8) disposed in a thin film formation chamber (5) whose inside can be decompressed, and opening in an upper space of the substrate holder (8). From (6),
A method of forming a thin film of CVD by supplying a source gas onto a substrate (3) disposed on the substrate holder (8) and forming a thin film (4) on the substrate surface (3a) by chemical vapor deposition. Wherein the internal pressure in the thin film formation chamber (5) is 0.1 to 100 Torr.
r, the radius a (cm) of the single tubular member (6), the flow rate V (cm / min) of the raw material gas in the single tubular member (6), and the flow rate of the raw material gas. The Reynolds number Re (Re = aV / ν) of the raw material gas flow defined between the kinematic viscosity coefficient ν (cm ² / min) and the substrate surface (3a) to the single circular pipe member (6) 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 pipe member (6) is as follows. L = αR D = βR where α is 0.9 to 1.2 β is 0 if the Reynolds number Re is 1000 or less.
03 or less, if it is more than 1000, keep it at 0.05 or less and include lead-zirconia-titanium metal oxide
A CVD thin film forming method for forming a perovskite compound thin film. And a laser beam irradiating means (12) for irradiating a laser beam (2) to a space above the substrate on which the thin film is to be formed, wherein the thin film forming chamber (5) is provided with a laser beam irradiating means (12). The method for forming a CVD thin film according to claim 1, wherein the film is formed by supplying the light from the light (2).