JP4704894B2 - Film forming method and film forming apparatus - Google Patents

Description

The present invention relates to a film forming method and a film forming apparatus for forming a film on a substrate by a CVD method (chemical vapor deposition method), in particular, a SiO ₂ film, an ITO film (transparent conductive film), SnO _{2 on} a glass substrate or the like. The present invention relates to a film forming method and a film forming apparatus for forming an (ATO, FTO) film, a magnesium oxide (MgO) film, a zinc oxide (ZnO) film, and the like.

The following are known as conventional film forming apparatuses.
Japanese Patent No. 2818776

  The film forming apparatus 50 of Patent Document 1 shown in FIG. 6 is a raw material gas (fine particles which are film forming components and a carrier gas which carries the raw material gas mixed and supplied at a supply port 52 provided at one end of a liner tube 51. Gas mixture) through the flow path 53 to the film forming chamber 54. The film forming chamber 54 is provided with a susceptor 56 having a substrate 57 in the lower part thereof and an installation surface and a heating device. The width of the upper part of the film forming chamber 54 is substantially the same as that of the substrate 57, and the height thereof is It is a structure which becomes narrow gradually toward the film | membrane room exit 59, and the cross section is a thin rectangular shape as shown in FIG.7 (D).

  The film forming apparatus 50 guides the source gas from the supply port 52 through the flow path 53 to flow into the film forming chamber 54, and the inflowed source gas is flowing along the surface of the substrate 57 heated by the susceptor 56. It has a function of generating a film.

  Since the film forming apparatus 50 is a film forming apparatus that causes the source gas to flow along the surface of the substrate as compared with the film forming apparatus that causes the source gas to collide with the substrate, the influence of the rising air current from the heated substrate is affected. Film formation efficiency (rate in which fine particles in the source gas stay on the substrate) is good.

However, the cross-sectional shape of the flow path 53 of the film forming apparatus 50 changes from a supply port 52 to a film forming chamber inlet 58 into a circle, an ellipse, and a thin rectangle as shown in FIGS. It is the structure to do. For this reason, the flow velocity distribution in the width direction of the source gas that has reached the film forming chamber 54 is unlikely to be uniform.
In other words, the source gas injected in a circular shape at the supply port 52 is guided to the film formation chamber inlet 58 according to the change in the cross-sectional shape of the flow path 53. Therefore, the flow velocity distribution in the cross-section continues to maintain the injection shape. Therefore, the speed of the central portion on the extension line of the supply port 52 becomes faster than the peripheral portion. Due to this influence, the flow velocity distribution in the width direction in the film forming chamber 54 also tends to be faster in the central portion than in the peripheral portion.

  Since the thickness of the film on the substrate formed by the film forming apparatus for flowing the source gas has a tendency to change corresponding to the flow rate of the source gas, the source gas in the film forming chamber 54 as in the prior art. If the flow velocity distribution of the film is not uniform and is disturbed, the thickness of the generated film is difficult to be uniform. In addition, since the change in the cross-sectional shape of the flow path becomes larger as the substrate becomes larger (the substrate area is larger) in the apparatus for introducing the source gas, the disturbance in the flow velocity distribution of the source gas is more remarkable, and it becomes a film deposition apparatus for a large substrate. Becomes extremely unsuitable.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a film forming method and a film forming apparatus capable of forming a large substrate with a uniform film thickness. .

Means and effects for solving the problems

In the present invention, a film forming chamber formed between a susceptor and an upper body via a spacer, and a concave portion corresponding to a substrate thickness provided in the susceptor, the surface of which forms the same plane as the susceptor surface a substrate, a mixing chamber a raw material gas was be supplied from the inlet opening the entire surface of the deposition chamber and connected to the inlet end of the deposition chamber,
A plurality of source gas supply pipes connected to the mixing chamber and opened,
Wherein a rectangular parallelepiped space ultrathin the space on the substrate of the film forming chamber,
Furthermore, the sectional area of the inlet opening of the film forming chamber is set to a value smaller than the total sectional area of the openings of the plurality of source gas supply pipes .

  According to this means, since the mixing chamber is connected to the inlet end of the film forming chamber, the source gas supplied from the supply pipe is mixed in the mixing chamber and then guided to the film forming chamber. Since the mixing chamber is connected to the inlet end of the film forming chamber so that the source gas can be supplied from the entire entrance opening of the film forming chamber, the distribution of the supply speed of the source gas is distributed on the substrate surface in the film forming chamber. It does not affect the flow velocity distribution of the source gas flowing along. In addition, since the space on the upper surface of the substrate that forms the same plane as the susceptor surface in the recess of the film formation chamber is an extremely thin rectangular parallelepiped, the flow velocity distribution in the width direction of the source gas flowing into the film formation chamber is The position is almost constant in the width direction. In addition, since the substrate surface is flush with the susceptor surface, the flow of the source gas is not disturbed. And since the height of the space on the substrate, that is, the height of the flow path of the source gas is very small, it is possible to heat even a fluid having a small heat transfer coefficient such as the source gas, and the source gas flowing in the space on the substrate It is easy for the whole to reach the reaction temperature. In addition, since the reaction temperature is reached only in the space on the substrate, there is an effect that there is no possibility that film forming components adhere to other than the substrate.

Further, according to the above means, since the pressure in the mixing chamber can be controlled higher than that in the film forming chamber, there is an effect that the source gas can be stably supplied to the film forming chamber.

The present invention is characterized in that an opening direction of the plurality of source gas supply pipes to the mixing chamber is set to intersect or face each other.
According to the above means, since mixing in the mixing chamber results in collision mixing of the source gases, both flow velocities are alleviated by collision between gas molecules or attraction between gas molecules, and the direction is also dispersed in a direction different from the partner. In addition, stable rectification of the source gas is facilitated.

In the present invention, the flow rate distribution of the source gas flowing along the surface of the substrate is adjusted by adjusting the flow rate of the source gas flowing into the film forming chamber from the plurality of source gas supply pipes. It is characterized by being uniform in a direction (hereinafter also referred to as “substrate width direction”) perpendicular to the flow direction (hereinafter also referred to as “substrate length direction”).
According to this means, since the distribution of the flow velocity of the source gas flowing along the surface of the substrate disposed in the film forming chamber is uniform in the width direction of the substrate, a film having a uniform thickness in at least the width direction can be obtained. It has the effect. After that, it is only necessary to control the film thickness so as to be uniform in the length direction, so that the control is simplified.

The present invention, connecting part of the film forming chamber of the mixing chamber is characterized by having a smooth guide surface for the cross-sectional area toward the the deposition chamber is reduced.
This means has an effect that rectification can be performed more smoothly.

The present invention is characterized in that the mixing chamber has a heating device for preheating the raw material gas.
According to this means, it becomes easy to preheat the raw material gas to a temperature slightly lower than the thermal decomposition temperature in the mixing chamber, and the thermal decomposition temperature is reached in the film forming chamber by supplying it to the film forming chamber in a preheated state. This has the effect of shortening the time until.

Further, the present invention is characterized in that a discharge chamber having substantially the same structure as the mixing chamber is provided symmetrically at the outlet side end of the film forming chamber.
According to this means, by configuring the discharge chamber and the mixing chamber in substantially the same structure, the supply direction of the source gas can be switched with a simple configuration such as a switching valve, and the film formation tendency on the substrate in the film formation chamber Can be offset.

The present invention, the space on the substrate of the film forming chamber, characterized in that it is formed narrower in accordance with the flow direction of the raw material gas.
According to the above means, it is possible to sequentially increase the flow rate of the source gas in the film forming chamber.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view (a cross-sectional view taken along line AA in FIG. 2) of a film forming apparatus according to an embodiment of the present invention, and FIG. 2 is a transverse sectional view (B in FIG. 1) of the film forming apparatus. -B sectional view). FIG. 3 is a partially enlarged view of the film forming apparatus (part C in FIG. 1). FIG. 4 is an explanatory diagram showing the flow velocity distribution of the source gas flowing in the film forming chamber of the film forming apparatus, and FIG. 5 is an explanatory diagram showing the relationship between the flow direction of the source gas in the film forming chamber and the film forming tendency. FIG.

1 and 2, reference numeral 10 denotes a film forming apparatus. The main body of the film forming apparatus 10 includes an upper main body 11, a lower main body 12, a susceptor 13 and a spacer 14 provided on the lower main body, and is formed by integrally connecting them.
The susceptor 13 is provided with a recess 30 having a depth corresponding to the thickness of the substrate 18. The substrate 18 is held in the recess 30 of the susceptor 13 so that the surface thereof is flush with the surface of the susceptor 13. Formed.

The film forming chamber 17 is formed between the susceptor 13 having the concave portion 30 and the upper main body 11 via the spacer 14. When the substrate 18 is held in the recess 30 of the susceptor 13 as described above, an extremely thin rectangular parallelepiped space is formed on the substrate in the film forming chamber. The length a and the width b of the space on the substrate are defined by the length and width of the substrate, and the height h is defined by the height of the spacer 14.
The height h of the space on the substrate is preferably from 0.3 mm to 3.0 mm.

  Since the surface of the substrate 18 held in the concave portion 30 of the susceptor 13 is formed so as to be flush with the surface of the susceptor 13, there is no possibility of disturbing the flow of the source gas. And since the height of the space on the substrate, that is, the height of the flow path of the source gas is very small, it is possible to heat even a fluid having a small heat transfer coefficient such as the source gas, and the source gas flowing in the space on the substrate It is easy for the whole to reach the reaction temperature, and since the reaction temperature is reached only in the space on the substrate, there is an effect that there is no possibility that the film forming components adhere to other than the substrate.

A heating device 24 for heating the substrate 18 held in the recess of the susceptor 13 is built in the lower body 12. By this heating device 24, the source gas flowing on the substrate 18 is heated and thermally decomposed to form a film on the substrate.
The heating device 24 is provided so as to heat an area slightly larger than the substrate 18, and is wide enough to heat the mixing chamber 15, and also serves as a preheat source gas in the mixing chamber 15 described later. However, the heating device for preheating the raw material gas in the mixing chamber 15 does not need to be integrated with the heating device 24 and may be provided with another heating device.

The film forming apparatus 10 includes a main body configured as described above, a mixing chamber 15 provided on the left side thereof, and a discharge chamber 16 provided on the right side.
In FIG. 3, the mixing chamber 15 is provided between the three source gas supply pipes 20 and the film forming chamber 17, and the connection area with the film forming chamber 17 decreases in cross section toward the film forming chamber 17. The width of the end portion on the film forming chamber 17 side is equal to or wider than the width of the inlet opening 19a of the film forming chamber 17.
The sectional area of the film forming chamber inlet opening is smaller than the total sectional area of the openings of the three supply pipes.
Further, the source gas supply pipe 20 is connected to and opened in the mixing chamber 15, but the opening direction is two in the horizontal direction, and the other one intersects the two in the same horizontal plane. Yes.

Thus, the width of the end portion of the mixing chamber 15 on the side of the film forming chamber 17 is formed to be equal to or wider than the width of the inlet opening 19a of the film forming chamber 17, so that the source gas is formed from the entire surface of the inlet opening. The flow velocity distribution in the width direction of the inflowing raw material gas flows into the membrane chamber 17 and becomes almost constant. Further, since the cross-sectional area of the film-formation chamber inlet opening is smaller than the total cross-sectional area of the three supply pipe openings, the pressure in the mixing chamber can be made higher than that in the film-formation chamber. Gas can be stably supplied into the deposition chamber.
The larger the pressure difference, the faster the flow rate of the source gas in the film forming chamber, but the flow rate range at the inlet opening is preferably 0.3 m / sec or more and 8 m / sec or less. If the flow velocity is out of this range, the uniformity of the flow velocity distribution in the width direction at the inlet opening deteriorates.

Furthermore, since the opening directions of the three supply pipes 20 face each other or cross each other, the source gases to be supplied are mixed with each other in the mixing chamber.
According to the collision mixing of the source gases, both flow velocities are alleviated by collision between gas molecules or attractive force between gas molecules, and the flow direction is dispersed in a direction different from the other, so that the deviation in flow velocity distribution is reduced. Thus, the influence on the flow velocity distribution of the raw material gas flowing into the inlet opening of the film forming chamber is further reduced. Therefore, there is an effect that stable rectification of the source gas is facilitated.

As described above, it is preferable to provide a preheating device (not shown) for preheating the raw material gas in the mixing chamber. If the source gas is preheated to a temperature equal to or lower than the thermal decomposition temperature by this preheating device, the film formation time in the film formation chamber can be shortened.
And it is preferable to provide the preheating device separately from the heating device 24 of the substrate 18 because the temperature can be adjusted independently.

The discharge chamber 16 provided on the outlet 19b side of the film forming chamber 17 is configured in substantially the same manner as the mixing chamber 15 provided on the inlet 19a side of the film forming chamber.
That is, the mixing chamber 15 and the discharge chamber 16 are provided via the film forming chamber 17, and the substantially same structure is provided symmetrically. Therefore, the supply direction of the source gas can be switched using a switching valve or the like. As will be described later, by switching the supply direction, the tendency of film formation in the flow direction of the source gas can be offset, and the film thickness in the length direction of the surface of the substrate 18 can be made uniform.

  In the above embodiment, the space on the substrate 18 in the film forming chamber 17 has a rectangular parallelepiped shape, but it may be formed narrower in the downstream direction. When the space on the substrate is a rectangular parallelepiped, the tendency of film formation decreases as it goes downstream. However, since the flow rate of the raw material gas can be increased as it goes downstream, the tendency of film formation in the length direction is increased. Can be made uniform.

  Next, a film forming method according to an embodiment of the present invention will be described in detail along with the operation of the film forming apparatus 10. The source gas supplied through the supply pipe 20 collides and mixes in the mixing chamber 15 and flows into the film forming chamber 17. Fine particles that are film forming components in the source gas in the film forming chamber 17 are heated and thermally decomposed on the surface of the substrate 18 and deposited on the substrate to form a film.

  In the film forming operation described above, the source gas to the film forming chamber 17 is mixed on the upstream side before the film forming chamber due to the presence of the mixing chamber 15 and is supplied from the entire entrance opening 19a of the film forming chamber. That is, since the width of the end of the mixing chamber 15 on the film forming chamber side is larger than the width b of the inlet opening of the film forming chamber 17, the source gas flows into the film forming chamber from the entire inlet opening of the film forming chamber. Therefore, the distribution of the supply flow rate of the source gas does not affect the flow rate distribution in the film forming chamber.

  Therefore, by making the flow velocity distribution of the source gas supplied from the mixing chamber 15 uniform, the flow velocity distribution of the source gas flowing along the surface of the substrate is perpendicular to the flow direction (the width direction of the substrate). ), The film thickness is at least uniform in the width direction.

  Since the sectional area of the inlet opening of the film forming chamber 17 is set to a value smaller than the total cross section of the openings of the three supply pipes 20 to the mixing chamber 15, the pressure in the mixing chamber may be higher than that of the film forming chamber. Can be supplied stably. In addition, since the opening directions of the three supply pipes 20 to the mixing chamber are opposed to or intersecting with each other, the supplied source gases collide with each other in the mixing chamber and are mixed as described above. is there. Further, the connecting portion between the mixing chamber 15 and the film forming chamber 17 is a smooth guiding surface whose cross-sectional area decreases toward the film forming chamber 17, so that the mixed raw material gas having a uniform flow velocity distribution can be smoothly supplied. It can be introduced into the film formation chamber inlet opening 19a.

The simulation result of the flow velocity distribution of the source gas in the space on the substrate in the film forming chamber 17 will be described with reference to FIG.
In FIG. 4, the horizontal axis indicates the distance in the width direction from the center of the film forming chamber 17 in the width direction, and the vertical axis indicates the flow rate of the source gas with the distance from the film forming chamber inlet 19a to the outlet 19b as a parameter. is there. Inflow conditions of the raw material gas into the mixing chamber 15 from the supply pipe 20 of the deposition chamber direction is 2m / s, the same is in a direction perpendicular supply pipe 20 of a 4m / s.
Further, the supply speed of the source gas, that is, the flow rate of the source gas at the film formation chamber inlet 19a is adjusted and supplied so as to be about 8 m / s.

As is clear from FIG. 4, since the source gas supplied at the flow velocity V0 m / s at the film formation chamber inlet 19a is heated in the film formation chamber 17, it thermally expands, and the speed increases as it goes downstream. , V10, V20, and V30 at positions 10 mm, 20 mm, and 30 mm from the inlet 19a, respectively, but a substantially uniform flow velocity distribution is maintained in the width direction in any cross section.
In this way, since the flow rate of the source gas is kept uniform in the width direction in the film forming chamber 17, a film having a uniform thickness in the width direction is generated.

Next, the film forming tendency in the length direction will be described with reference to FIG.
The tendency of film formation between the inlet 19a of the film forming chamber 17 and the outlet 19b of the film forming chamber first increases as the flow rate and temperature of the source gas increase as shown by the line 4a in FIG. Moreover, it turned out that it becomes small as shown to the line 4b as it distances from an entrance (this seems to be because the film-forming component fine particle in source gas is consumed and the quantity reduces).
In the film forming chamber 17, a decreasing tendency 4b due to the consumption of the film forming component fine particles and an increasing tendency 4a due to the flow velocity and the temperature occur simultaneously. For this reason, the film forming tendency from the film forming chamber inlet 19a toward the film forming chamber outlet 19b shows a substantially constant tendency as shown by a line 4c.

However, since these two tendencies are not completely offset, the deposition tendency 4c may be slightly inclined depending on the distance from the entrance.
In that case, by providing the mixing chamber 15 and the discharge chamber 16 having substantially the same structure at both ends of the film forming chamber 17, the flow direction of the source gas on the substrate is switched by a switching valve or the like at every predetermined time and supplied. Since the flow direction of the source gas is switched to the opposite direction, the film forming tendency 4c is offset and a film having a uniform thickness in the length direction can be generated.

  Since the heating device 24 extends to the lower part of the mixing chamber, the mixing chamber 15 has a function of mixing source gases and preheating. Therefore, by mixing, the rectification in the film forming chamber 17 is kept uniform, the thickness of the generated film is made uniform, and the source gas is preheated, so that heat is generated when it flows into the film forming chamber 17. The decomposition temperature is reached quickly, and the film formation time can be shortened. In this embodiment, the preheating of the source gas is integrated with the heating device 24 for heating the substrate 18, but may be provided separately. Providing separately is preferable because the preheating temperature can be independently controlled.

  In the above embodiment, the three supply pipes 20 and the discharge pipes 21 are used to supply the source gas, and the opening directions thereof intersect or face each other. However, the present invention is not limited to this. Any material may be used as long as the distribution of the supply speed to the film formation chamber inlet is uniform, and a configuration in which the source gases do not collide with each other and a configuration other than three supply tubes or discharge tubes are included. Furthermore, although the guide surface 27 is a flat surface, it is sufficient to guide the source gas, so that the curved surface or the like may be changed as appropriate.

It is a longitudinal cross-sectional view of the Example of this invention. It is a cross-sectional view of the Example of this invention. It is the elements on larger scale of the Example of this invention. It is a flow velocity distribution map of the source gas in the film formation chamber in the present invention. It is a figure which shows the characteristic of a film-forming tendency. It is the elements on larger scale of a prior art. It is sectional drawing of each part of the flow path of a prior art.

DESCRIPTION OF SYMBOLS 10 Film-forming apparatus 11 Upper main body 12 Lower main body 13 Susceptor 14 Spacer 15 Mixing chamber 16 Discharge chamber 17 Deposition chamber 17 Substrate 19 Open end 19a Deposition chamber inlet 19b Deposition chamber outlet 20 Supply pipe 21 Discharge pipe 22 Supply port 24 Heating Device 27 Guide surface 30 Recess

Claims (7)

A film forming chamber formed through a spacer between the susceptor and the upper body;
A substrate that is held in a recess corresponding to the substrate thickness provided in the susceptor and whose surface forms the same plane as the susceptor surface;
A mixing chamber which is capable of supplying the raw material gas from the inlet opening the entire surface of the deposition chamber and connected to the inlet end of the deposition chamber,
A plurality of source gas supply pipes connected to the mixing chamber and opened,
Wherein a rectangular parallelepiped space ultrathin the space on the substrate of the film forming chamber,
Further, the chemical vapor deposition apparatus characterized in that the sectional area of the inlet opening of the film forming chamber is set to a value smaller than the total sectional area of the openings of the plurality of source gas supply pipes . The chemical vapor deposition apparatus according to claim 1, wherein an opening direction of the plurality of source gas supply pipes to the mixing chamber is set to intersect or face each other. By adjusting the flow rate of the source gas flowing into the film forming chamber from the plurality of source gas supply pipes, the distribution of the flow rate of the source gas flowing along the surface of the substrate is orthogonal to the flow direction. 3. The chemical vapor deposition apparatus according to claim 1, wherein the chemical vapor deposition apparatus is uniform in a direction. Chemical vapor according to any one of claims 1 to 3 connecting part of the film forming chamber of the mixing chamber is characterized by having a smooth guide surface that decreases in cross sectional area toward the film forming chamber F Phase deposition system. Said mixing chamber, a chemical vapor deposition apparatus according to any one of claims 1 to 4, characterized in that it comprises a heating device for preheating the raw material gas. Wherein the outlet end of the deposition chamber, a chemical vapor deposition apparatus according to any one of claims 1 to 5, characterized in that the discharge chamber of the mixing chamber and the same structure is provided symmetrically. Wherein said space on the substrate of the deposition chamber, a chemical vapor deposition apparatus according to any one of claims 1 to 6, characterized in that it is formed narrower in accordance with the flow direction of the raw material gas.

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