JP4708167B2 - Film forming apparatus and film forming method - Google Patents

Description

  The present invention relates to a film forming apparatus and a film forming method, and more particularly to a film forming apparatus and a film forming method for forming a metal oxide film or a metal nitride film.

  Recently, in CVD (Chemical Vapor Deposition), as shown in Patent Document 1, from an injection valve provided on the top of a substrate placed inside a film forming chamber, A new film forming method (hereinafter referred to as a spraying method) is being developed in which a film forming material is sprayed in a liquid state in the form of a mist. According to such a spraying method, it is not necessary to heat a vaporizer, piping, etc., so that the size and cost of the apparatus can be reduced.

  By the way, in this spraying method, in order to ensure film quality, the mist-like liquid film-forming material ejected from the injection valve is vaporized (gasified) reliably and as uniformly as possible before reaching the substrate. )

In response to this requirement, it is easy to think that the liquid film-forming material should be ejected widely in a uniform mist form from the injection valve, like a fuel injection valve used in an engine or the like. Actually, such a configuration may cause insufficient vaporization and deteriorate film quality. The structure and concept of a fuel injection valve for an engine cannot be adopted as it is.
JP2004197135

  In view of such problems, the present inventor has conducted various experiments and intensively studied. As a result, the inventors have devised what type of spraying is suitable for this type of film forming apparatus and arrived at the present invention for the first time. The main intended problem is to provide a spray-type CVD film forming apparatus and the like that can guarantee film quality, and can reduce the size and cost of the apparatus.

  That is, a film forming apparatus according to the present invention includes a film forming chamber that houses a substrate therein, an injection valve that is disposed at a predetermined distance from the substrate, and injects a film forming material into the film forming chamber in a liquid state, The cross-sectional shape of the injection hole provided in the injection valve is substantially constant in the lateral direction, and gradually expands in the longitudinal direction from the inlet toward the outlet, and in the vicinity of the outlet It is comprised so that it may make at least an elongate strip shape. The band shape may be any shape that has a front end and a terminal end and is not closed, and includes a shape that extends linearly, a portion that is curved in a partial arc shape, a wave shape, or a triangular wave shape. .

  If it is such, since the spray shape of the film-forming raw material immediately after being injected from the injection valve becomes a substantially fan-shaped thin film shape, the vaporization efficiency is improved as much as possible, and other for vaporization Without special measures (such as making the film formation chamber larger and setting the separation distance between the injection valve and the substrate large, or setting the pressure in the film formation chamber to be particularly low). It is possible to easily prevent the film-forming raw material from reaching the liquid state, and to ensure the quality of the film.

  Moreover, the parameter regarding the preferable injection hole which this inventor discovered as a result of earnest examination is as follows.

  That is, it is preferable that the dimension in the short direction in the cross-sectional shape of the injection hole is between about 0.15 mm and about 0.20 mm. The depth dimension of the injection hole is preferably between about 0.45 mm and about 1.4 mm. The expansion angle of the injection hole is preferably an angle between about 50 ° and about 130 °. The distance from the virtual expansion center point of the injection hole to the inlet of the injection hole is preferably between about 0.4 mm and about 1 mm. The dimension in the depth direction of the injection hole is preferably about 3 to about 7 times the dimension in the short direction.

  The injection valve is preferably of a pivot type. As a specific aspect thereof, a liquid film forming raw material is filled in the internal space and the injection hole is penetrated through the tip, and the body is disposed so as to be able to advance and retreat in the body. The valve body is seated on or separated from the valve seat provided on the inner surface on the base end side from the injection hole in the body, so that the internal space of the injection hole and the body Can be mentioned.

  As described above, according to the present invention, the spraying shape of the film forming raw material injected from the injection valve becomes a substantially fan-shaped thin film shape, so that the vaporization efficiency is improved as much as possible. As a result, it is possible to prevent the film-forming raw material from reaching the substrate in a liquid state without causing an increase in size and complexity of the apparatus, and high-quality film formation is possible.

Next, an embodiment of a film forming apparatus according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, a film forming apparatus 1 according to this embodiment includes a film forming chamber 3 that holds a substrate 2 therein, and an injection valve that directly injects a film forming material into the film forming chamber 3 in a liquid state. 4, a raw material supply pipe 5 for supplying a liquid film forming raw material to the injection valve 4, a control device 11 for controlling the injection valve 4, and the like, and the film forming raw material sprayed from the injection valve 4 However, it is configured to vaporize in the middle and deposit on the substrate 2 to be processed to form a thin film.

In the present embodiment, in order to form an Nb ₂ O ₅ film on the substrate 2, pentaethoxyniobium (PENb, Nb (OC ₂ H ₅ ) ₅ ), which is an organic niobium compound, is used as the film forming raw material. However, since this pentaethoxyniobium alone has a very low vapor pressure and is difficult to vaporize, ethanol, which is a low-boiling organic compound, is mixed with this at a predetermined ratio (for example, 6: 4, however, mol ratio). The mixed solution is supplied to the injection valve 4. More specifically, this mixed solution is stored in, for example, a stainless steel container 6, and the injection valve passes through the raw material supply pipe 5 with the pressurized gas (N ₂ or Ar gas) press-fitted into the container 6. 4 is configured to be supplied to the inside of the film forming chamber 3 via 4. Note that the raw materials for film formation and the low-boiling organic compounds are not limited to those described above, and for example, a combination of pentaethoxytantalum (Ta (OC ₂ H ₅ ) ₅ ) and n-pentane (nC ₅ H ₁₂ ) may be used.

As shown in FIG. 1, the film forming chamber 3 holds and accommodates the substrate 2 to be processed by a holding mechanism (not shown), and the internal accommodating space is a mixture injected into the film forming chamber 3. The internal pressure is adjusted so that pentaethoxyniobium in the solution is vaporized. That is, the pressure in the film forming chamber 3 is larger than the saturated vapor pressure of pentaethoxyniobium before mixing with ethanol and smaller than the saturated vapor pressure of the mixed solution of ethanol and pentaethoxyniobium. For example, it is set to about 17 to 100 Pa. The film forming chamber 3 is further provided with a substrate heater 7 for heating the substrate 2 and an oxygen supply pipe 9 for supplying oxygen (O ₂ ) gas for sufficiently oxidizing the Nb ₂ O ₅ film. Has been. The oxygen supply pipe 9 is controlled by an oxygen (O ₂ ) gas supply flow rate by a mass flow controller (MFC) 10.

  As shown in FIG. 1, the injection valve 4 directly injects the mixed solution containing the film forming raw material into the film forming chamber 3 in a liquid state (mist form). It is provided so as to face the deposition surface of the substrate 2.

  More specifically, as shown in FIGS. 2 to 4, the injection valve 4 is a body 41 in which the mixed solution is filled in an internal space, and the injection hole H is passed through the tip portion. The valve body 43 is disposed in the body 41 so as to be able to advance and retract, and is a pivot type that includes an electromagnetic coil 42 and a spring 44 that apply advancing and retracting forces along opposite axial directions to the valve body 43. .

  The body 41 includes a cylindrical body main body 41A and an injection hole forming portion 41B provided continuously at the tip of the body main body 41A. The inner surface of the tip of the body main body 41A is formed in an inverted conical shape. A valve seat 411 is formed. The injection hole forming portion 41B is a hollow spherical portion provided further on the distal end side from the valve seat 411, and the injection hole H is passed through the wall body.

  The valve body 43 is arranged in the axial direction of the injection valve 4 between the closed position where the valve body 411 is seated and the open position which is separated from the valve seat 411 due to the magnitude relationship between the electromagnetic coil force and the spring force. It moves forward and backward. More specifically, when a closing signal is output from the control device 11, the electromagnetic coil 42 is not excited, the valve element 43 is held in the closing position by a spring force, and the injection hole H is formed in the body 41. Is cut off from the interior space. In this state, the liquid mixed solution (film forming raw material) is not ejected. When the opening signal is output from the control device 11, a current flows through the electromagnetic coil 42, the valve body 43 is held in the opening position, and the injection hole H communicates with the internal space of the body 41. In this state, the liquid mixed solution (film forming raw material) is sprayed into the film forming chamber 3 in the form of a mist from the injection hole H, and is vaporized by the reduced-pressure boiling spray action. The ejection pressure can be in the range of about 0.1 to 1 MPa, but here it is set to about 0.4 to 0.5 MPa, for example.

  The control device 11 periodically opens and closes the injection valve 4 to intermittently supply the liquid mixed solution into the film forming chamber 3, and the liquid in the raw material supply pipe 5 using the pressure gauge 12. While observing the pressure of the mixed solution, the injection valve 4 is controlled so that a predetermined amount of the liquid mixed solution is ejected.

  As shown in FIG. 6, the specific control method includes a supply time that is a time for supplying the liquid mixed solution into the film forming chamber 3 and a supply stop that is a time for not supplying the liquid mixed solution into the film forming chamber 3. The injection valve 4 is controlled so as to periodically repeat the time. The supply stop time is set to be about 50 times or more of the supply time. In this embodiment, for example, the supply time is 10 [ms] and the supply stop time is 990 [ms]. The supply time is set based on, for example, the film formation target area of the substrate 2, the pressure in the film formation chamber 3, the volume, the film formation raw material (liquid mixed solution), or the like. The supply stop time is supplied to the film formation chamber 3 during the supply time, and atoms or molecules of the film forming raw material deposited on the substrate 2 migrate and the reaction by-product generated on the substrate 2 evaporates. Set to be the same as or longer than the electrophoresis / evaporation time required for Note that ON / OFF may be repeated more finely during the supply time.

  Thus, in this embodiment, as shown in FIGS. 3, 4, and 5, the transverse dimension B of the injection hole H is made substantially constant (see FIG. 3, from the longitudinal direction). It is a longitudinal sectional view of the injection hole H as viewed from the back, and gradually expands from the back (inlet) toward the outlet in the longitudinal direction (see FIG. 4, in the longitudinal sectional view of the injection hole H viewed from the short direction) In the vicinity of the outlet, it is configured to have at least an elongated straight belt shape (see FIG. 5, the shape of the injection hole H as seen from the outlet direction). In other words, the injection hole H is formed in a slit shape and has a general sector shape (see FIG. 4) that extends toward the outlet when viewed from the side.

Detailed dimensions of each part of the injection hole H are as follows.
That is, the transverse dimension B of the cross-sectional shape of the injection hole H is about 0.15 mm to about 0.20 mm, and the depth dimension L of the injection hole H is about 0.45 mm to about 1.4 mm. The expansion angle θ of the injection hole H is about 50 ° to about 130 °, and the distance R from the virtual expansion center point C of the injection hole H to the inlet of the injection hole H is about 0.4 mm to about 1 mm. The depth direction dimension L in the injection hole H is set between about 3 times and about 7 times the dimension B in the short direction.

  The spraying mode of the liquid film-forming material by the injection valve 4 configured in this way is illustrated in FIGS. 7, 8, and 9 in comparison with other types of injection valves under the same conditions. In the case of the swirl type injection valve, the spray forms a liquid film in a hollow conical shape like a skirt and is injected while swirling (see FIG. 8). Further, in the case of a porous injection valve provided with a large number of fine pores of equal cross section, the spray is injected in a columnar shape (solid conical shape) while spreading (see FIG. 9). On the other hand, in the case of the injection valve 4 according to this embodiment, the spray is injected into a fan-shaped thin liquid film (see FIG. 7).

  FIG. 7 clearly shows that the spray is vaporized at a short distance, whereas FIGS. 8 and 9 clearly require a long distance to vaporize. This is thought to be because if the spray is columnar regardless of whether it is hollow or solid, vaporization inside the spray is hindered due to a local increase in pressure inside the columnar spray, and the vaporization efficiency decreases.

  On the other hand, in the case of the injection valve 4 according to the present embodiment, the spraying shape of the film-forming raw material (mixed solution) immediately after being injected from the injection valve 4 becomes a substantially fan-shaped thin film shape. Improve as much as possible. As a result, it is possible to easily prevent the film forming raw material from reaching the substrate 2 in a liquid state, thereby ensuring the quality of the film.

  The present invention is not limited to the above embodiment.

  As described above, since it is sufficient that the spray does not have to be in the form of a liquid column (including a hollow), at least the outlet shape of the injection hole may be a strip shape that has a front end and a terminal end and is not closed. In addition to the linearly extending shape as in the form, it may be curved in a partial arc shape, a wave shape, or a triangular wave shape. A plurality of injection holes may be provided in one injection valve, for example, in parallel.

  Moreover, in the said embodiment, although the injection hole was set slightly diagonally with respect to the axial direction of an injection valve (refer FIG. 3), you may make this parallel to an axis | shaft. Further, the injection hole forming portion 41B is not limited to the hollow portion spherical shape, and may have a square shape on both the inner and outer surfaces as shown in FIG. In that case, each dimension is defined as shown in the figure. In addition, the outer surface may be round and the inner surface may be square, or vice versa, and the shape of the injection hole forming portion 41B is not particularly limited.

  In the above embodiment, the injection valve is provided in the upper part of the film forming chamber so as to face the substrate. However, the injection valve may be provided in the lower part of the film forming chamber so as to face the substrate. The injection valve may be provided on the side surface of the film forming chamber so as to face the substrate.

  In addition, the present invention can be variously modified without departing from the gist thereof.

1 is a schematic configuration diagram of a film forming apparatus according to an embodiment of the present invention. The structural diagram which shows the internal structure of the injection valve in the embodiment. The fragmentary sectional view which shows the detail of the injection hole in the embodiment. The fragmentary sectional view which shows the detail of the injection hole in the embodiment. The partial detailed view seen from the exit of the injection hole in the embodiment. The control signal figure to the injection valve in the embodiment. The experimental data which show the actual spray shape of the injection valve in the embodiment. Experimental data showing spray shape of swirl type injection valve. Experimental data showing the spray shape of a multi-hole injection valve. The fragmentary sectional view which shows the detail of the injection hole in other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus 2 ... Board | substrate 3 ... Film-forming chamber 4 ... Injection valve
H ... Injection hole

Claims (10)

A film forming chamber that accommodates the substrate therein, and an injection valve that is disposed at a predetermined distance from the substrate and injects a film forming material into the film forming chamber in a liquid state,
The cross-sectional shape of the injection hole provided in the injection valve has a substantially constant dimension in the short side direction, and gradually expands from the inlet to the outlet in the long side direction, and at least in the vicinity of the outlet, has an elongated strip shape. A film forming apparatus configured to be made. 2. The film forming apparatus according to claim 1, wherein a dimension in a lateral direction of the cross-sectional shape of the injection hole is set between 0.15 mm and 0.20 mm . The film forming apparatus according to claim 1, wherein a depth dimension of the injection hole is set between 0.45 mm and 1.4 mm . The film forming apparatus according to claim 1, wherein an expansion angle of the injection hole is set to an angle between 50 ° and 130 ° . The film forming apparatus according to any one of claims 1 to 4, wherein a distance from a virtual expansion center point of the injection hole to an inlet of the injection hole is set between 0.4 mm and 1 mm . The film forming apparatus according to any one of claims 1 to 5, wherein a dimension in the depth direction of the injection hole is set to 3 to 7 times a dimension in the short direction. A film forming chamber that houses the substrate is provided at a predetermined distance from the substrate, and the film forming material is jetted in a liquid state toward the substrate.
It has injection holes for injecting the film forming raw material, and the cross-sectional shape of the injection holes is substantially constant in the short direction and gradually expands in the longitudinal direction as it approaches the outlet from the inlet. And a film forming apparatus injection valve configured to form at least an elongated strip in the vicinity of the outlet.   The film-forming raw material deposited on the substrate is jetted in a liquid state,
  It has injection holes for injecting the film forming raw material, and the cross-sectional shape of the injection holes is substantially constant in the short direction and gradually expands in the longitudinal direction as it approaches the outlet from the inlet. And a film forming apparatus injection valve configured to form at least an elongated strip in the vicinity of the outlet. A liquid film forming raw material is filled in an internal space, and includes a body formed by penetrating the injection hole at a tip portion thereof, and a valve body disposed in the body so as to be able to advance and retreat. The film forming apparatus according to claim 7 or 8 , wherein the film forming apparatus opens or closes the injection hole and the internal space of the body by being seated on or away from the valve seat provided on the inner surface on the base end side from the injection hole. Injection valve.   A vaporizer having an injection valve for injecting a film forming material to be deposited on a substrate in a liquid state;
  The injection valve has an injection hole for injecting the film forming raw material, and the cross-sectional shape of the injection hole has a substantially constant dimension in the lateral direction, and the closer to the outlet from the inlet in the longitudinal direction, A carburetor configured to gradually expand and form at least an elongated strip in the vicinity of the outlet.