JP5805553B2 - Deposition equipment - Google Patents

Description

  The present invention relates to a film forming apparatus.

  As a method for forming a film forming material on the surface of an object to be processed, for example, there is an ion plating method. In this ion plating method, a constant current supply current is supplied to a plasma generator to generate a plasma beam, and the film-forming material is heated and evaporated by the plasma beam in a vacuum vessel, and is formed on the surface of the object to be processed. A film material is attached to form a film. For example, Patent Document 1 discloses a film forming apparatus using such an ion plating method.

  In such a film forming apparatus, when it is necessary to change the film forming speed, the film forming speed is adjusted by changing the current value of the supply current. For example, when reducing the film formation rate, the film formation rate is adjusted by reducing the current value of the supply current.

JP 2009-221568 A

  However, although the film formation rate can be reduced to some extent by reducing the current value of the supply current, this adjustment method has its limitations. That is, when the electric power input with respect to the diameter of the film forming material is reduced, the entire surface of the film forming material is not evaporated. So-called leftovers occur. If this jump occurs, the film forming apparatus may not be stably operated for a long time.

  On the other hand, it is also possible to reduce the deposition rate by reducing the current value of the supply current and reducing the diameter of the deposition material. In this adjustment method, the supply current can be reduced without causing a jump, so that the film formation rate can be further reduced. However, hardware changes such as the main hearth holding the tablet are required.

  Therefore, the present invention has been made to solve such a problem, and it is possible to reduce the deposition rate without changing the hardware related to the material supply system accompanying the change in the diameter of the deposition material. An object is to provide a film forming apparatus.

  In order to solve the above problems, a film forming apparatus according to the present invention heats a film forming material with a plasma beam in a chamber, and deposits particles evaporated from the film forming material on an object to be formed. An apparatus comprising: a plasma generator for generating a plasma beam; and a power source for supplying a pulsed current to the plasma generator. The plasma generator is configured to generate a plasma beam based on a current supplied from the power source. Is generated.

  In this film forming apparatus, a pulsed current is supplied to the plasma generating apparatus, whereby the plasma generating apparatus alternately generates a high intensity plasma beam and a low intensity plasma beam. For this reason, compared with the case where a constant current is supplied to the plasma generator and a plasma beam with a constant intensity is continuously generated, the amount of particles vaporized from the film forming material can be reduced. As a result, it is possible to reduce the deposition rate without changing the hardware related to the material supply system accompanying the change in the diameter of the deposition material.

  The current may alternately have a maximum current value and a minimum current value. By supplying this current to the plasma generator, the plasma generator alternately generates a high intensity plasma beam and a low intensity plasma beam. For this reason, compared with the case where a constant current is supplied to the plasma generator and a plasma beam with a constant intensity is continuously generated, the amount of particles vaporized from the film forming material can be reduced. As a result, it is possible to reduce the deposition rate without changing the hardware related to the material supply system accompanying the change in the diameter of the deposition material.

  The maximum current value may be equal to or greater than the current value at which no film deposition material remains. In this case, when the current having the maximum current value is supplied to the plasma generator, the film forming material can be reliably vaporized.

  The minimum current value may be greater than the current value at which the plasma beam is extinguished in the plasma generator and less than the maximum current value. In this case, it is possible to prevent the plasma beam from disappearing in the plasma generator when a current having the minimum current value is supplied to the plasma generator. This eliminates the need to reignite the plasma beam in the plasma generator.

The power source may supply a current having periodically a maximum current value and a minimum current value to the plasma generator. In this case, the plasma generator periodically generates a high intensity plasma beam and a low intensity plasma beam. For this reason, it is possible to periodically change the amount of particles vaporized from the film forming material, and to suppress unevenness in the film thickness of the film formation target.

  A main anode for holding the film forming material and guiding the plasma beam may be further provided, and the maximum current value may be determined according to the size of the film forming material that can be held on the main anode. When the electric power input with respect to the size of the film forming material is reduced, the entire film forming material is not evaporated uniformly. Therefore, by determining the maximum current value according to the size of the film forming material, the film forming material can be surely vaporized when the current of the maximum current value is supplied to the plasma generator.

  According to the present invention, the film formation rate can be reduced without changing the hardware related to the material supply system accompanying the change in the diameter of the film formation material.

It is a schematic sectional drawing which shows the structure of the film-forming apparatus which concerns on this embodiment. It is a figure which shows an example of the supply current supplied to a plasma generator from the power supply of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic cross-sectional view showing a configuration of a film forming apparatus according to the present embodiment. The film forming apparatus 1 of the present embodiment is an ion plating apparatus used for a so-called ion plating method. In the drawing, an XYZ orthogonal coordinate system is also shown for ease of explanation. In the following description, the positive direction of the Z-axis is up, and the negative direction of the Z-axis is down.

  As shown in FIG. 1, a film forming apparatus 1 includes a plasma generator 2, a power source 3, a main anode 4, an auxiliary anode 5, a supply device 6, a transport mechanism 7, and a vacuum container 10 (chamber). .

  The vacuum vessel 10 is a vessel that forms a vacuum environment by a vacuum pump (not shown), is made of a conductive material, and is connected to a ground potential. The vacuum container 10 includes a transfer chamber 10a for transferring a substrate 11 (film formation object) as an object to be formed, a film formation chamber 10b for diffusing the film formation material Ma, and the plasma generator 2. And a plasma port 10c for receiving the plasma beam Pb irradiated from the inside of the vacuum vessel 10. The transfer chamber 10a, the film forming chamber 10b, and the plasma port 10c communicate with each other. The transfer chamber 10a extends in a predetermined transfer direction (arrow A in the figure) and is disposed on the film forming chamber 10b. In the present embodiment, the transport direction A is set along the X axis. In the film forming chamber 10b, the distance L between the inner surfaces facing each other along the transport direction A is, for example, about 500 mm.

The plasma generator 2 is a pressure gradient type plasma source, and its main body is provided on the side wall (plasma port 10c) of the film forming chamber 10b. The plasma generator 2 includes a glass tube 22 that is closed at one end by a cathode 21. In the glass tube 22, a cylinder 23 made of molybdenum (Mo) is fixed to the cathode 21. The cylinder 23 contains a disk 24 made of LaB ₆ and a pipe 25 made of tantalum (Ta). The pipe 25 is provided to introduce a carrier gas made of an inert gas such as argon (Ar) into the plasma generator 2.

  A first intermediate electrode 26 and a second intermediate electrode 27 are concentrically arranged in series between the end of the glass tube 22 opposite to the cathode 21 and the plasma port 10c. The first intermediate electrode 26 includes an annular permanent magnet 26a for converging the plasma beam Pb. The second intermediate electrode 27 includes an electromagnetic coil 27a for converging the plasma beam Pb. A steering coil 28 that guides the plasma beam Pb into the film forming chamber 10b is provided around the plasma port 10c.

  The power source 3 turns on / off the power supply between the cathode 21 and the main anode 4 of the plasma generator 2 and adjusts the supply current C to the cathode 21 and the like. The power source 3 supplies a pulsed supply current C, for example, a supply current C alternately having a maximum current value and a minimum current value between the cathode 21 and the main anode 4. For example, the power supply 3 supplies a supply current C of a pulse wave in which the maximum current value Imax and the minimum current value Imin are periodically repeated between the cathode 21 and the main anode 4. Details of the supply current C will be described later. The power source 3 adjusts the power supply to the first intermediate electrode 26 and the second intermediate electrode 27 via the resistor 31 and the resistor 32, respectively. The distribution state of the plasma beam Pb supplied into the vacuum vessel 10 is controlled by the power source 3, and in particular, the intensity of the plasma beam Pb is adjusted by adjusting the supply current C that is the supply current between the cathode 21 and the main anode 4. Is controlled.

  The main anode 4 is a part for holding the film forming material Ma and guiding the plasma beam Pb. The main anode 4 is provided in the film forming chamber 10 b and is disposed below as viewed from the transport mechanism 7. The main anode 4 has a main hearth 41. The main hearth 41 is a cylindrical member made of a conductive material, and an opening for filling the film forming material Ma is formed at the center of the main hearth 41. And the front-end | tip part of film-forming material Ma is exposed from this opening. The main hearth 41 is coupled to the plasma generator 2 and forms a plasma beam Pb with the cathode 21.

  The auxiliary anode 5 is a part for assisting the induction of the plasma beam Pb by the main anode 4. The auxiliary anode 5 is disposed around the main hearth 41 that holds the film forming material Ma, and includes an annular container 5a, and a coil 5b (electromagnet) and a permanent magnet 5c accommodated in the container 5a. The container 5a is made of a conductive material. The coil 5b and the permanent magnet 5c control the direction of the plasma beam Pb incident on the main hearth 41 or the direction of the plasma beam Pb incident on the film forming material Ma according to the amount of current flowing through the coil 5b.

  The supply device 6 is a device for supplying the film forming material Ma to the main hearth 41. The supply device 6 supplies the film forming material Ma below the main anode 4 according to the consumption of the film forming material Ma so that the tip portion of the uppermost film forming material Ma maintains a predetermined positional relationship with the upper end of the main hearth 41. Extrude sequentially.

  The transport mechanism 7 is composed of a plurality of transport rollers 71 installed in the transport chamber 10a. The transport mechanism 7 transports the tray 72 holding the substrate 11 at a constant transport speed B [mm / sec] in the transport direction A in a state facing the film forming material Ma. The transport rollers 71 are arranged at equal intervals along the transport direction A, and can transport the tray 72 in the transport direction A while supporting the tray 72. The substrate 11 is a plate-like member such as a glass substrate, a plastic substrate, and a semiconductor substrate.

  The film forming material Ma is a cylindrical tablet having a predetermined length and a diameter φ, and a plurality of film forming materials Ma are set in series on the main anode 4 at a time. The film forming material Ma is exemplified by a transparent conductive material such as ZnO doped with ITO and Ga. When the main hearth 41 is irradiated with the plasma beam Pb, the plasma beam Pb is directly incident on the film forming material Ma, the tip portion of the film forming material Ma is heated and evaporated (vaporized), and is ionized by the plasma beam Pb. The film forming material particles Mb diffuse into the film forming chamber 10b. The film forming material particles Mb diffused into the film forming chamber 10b move to above the film forming chamber 10b and adhere to the surface of the substrate 11 in the transfer chamber 10a.

  Since the substrate 11 is transported at the transport speed B along the transport direction A, the transit time td, which is the time required for the substrate 11 to pass over the film forming chamber 10b, is along the transport direction A of the film forming chamber 10b. The distance L between the inner surfaces facing each other divided by the conveyance speed B is L / B. Since both the distance L and the conveyance speed B are predetermined in the in-line type film forming apparatus 1, the passage time td is constant. For this reason, in the in-line type film forming apparatus 1, the film forming speed is changed by adjusting the amount of the film forming material particles Mb diffused into the film forming chamber 10b. Specifically, the film forming speed is increased by increasing the amount of the film forming material particles Mb, and the film forming speed is decreased by decreasing the amount of the film forming material particles Mb.

  FIG. 2 is a diagram illustrating an example of the supply current C supplied from the power source 3 to the plasma generator 2. As shown in FIG. 2, the supply current C is a pulse wave having a maximum current value Imax and a minimum current value Imin alternately in time series, and the maximum current value Imax and the minimum current value Imin are periodically repeated. is there. The maximum current value Imax is a current value for generating a plasma beam Pb having an intensity that is set according to the target film-forming speed Tr1 and does not cause the film-forming material Ma to remain. The remaining of the film forming material Ma occurs when the input power by the plasma beam Pb becomes smaller than the diameter φ of the film forming material Ma. Therefore, the lower limit value of the maximum current value Imax is determined according to the diameter φ of the film forming material Ma, and needs to be larger than the current value Ie at which jumping starts to occur.

  The minimum current value Imin is set in accordance with the target film formation rate Tr1, and is a current value smaller than the maximum current value Imax. Further, the minimum current value Imin may be set larger than the current value Io at which the plasma beam Pb disappears in the plasma generator 2. In this case, it is not necessary to re-ignite the plasma beam Pb in the plasma generator 2. Since the current value Io at which the plasma beam Pb disappears in the plasma generator 2 is normally 0 A, the minimum current value Imin is set to a value greater than 0 A and less than the maximum current value Imax.

  Further, the time (pulse width) τa for which the maximum current value Imax continues and the time (pulse width) τb for which the minimum current value Imin continues are set according to the conveyance speed B. A cycle T (= τa + τb) in which the maximum current value Imax and the minimum current value Imin are repeated is also set according to the conveyance speed B. When the duration τa and the duration τb are too large with respect to the transit time td required for the substrate 11 to pass over the film formation chamber 10b, the film thickness unevenness occurs along the transport direction A on the surface of the substrate 11. For this reason, the continuation time τa and the continuation time τb are set to be smaller as the conveyance speed B is larger, for example, set to 10 / B [sec] or less. The relationship between the final duration τa and the duration τb may be finely adjusted by experiment.

Next, the relationship between the maximum current value Imax, its duration τa, the minimum current value Imin, and its duration τb will be described. First, consider the case where the current value of the supply current is constant. Assuming that the supply current having the current value Is is used at the film formation rate Trs, the current value I1 of the supply current corresponding to the target film formation rate Tr1 (<Trs) is the following for the same film formation material Ma: (1).
I1 = (Tr1 / Trs) × Is… (1)

When a pulsed current is used as the supply current C, the relationship between the maximum current value Imax, the minimum current value Imin, the duration time τa and the duration time τb shown in FIG. , The following equation (2) is set.
I1 = (τa × Imax + τb × Imin) / (τa + τb) ... (2)

Furthermore, as described above, the maximum current value Imax, the minimum current value Imin, the duration time τa, and the duration time τb need to satisfy the following expressions (3) to (6). Since the current value Ie at which jumping starts to occur varies depending on the diameter φ of the film forming material Ma, the current value Ie corresponding to the diameter φ of the film forming material Ma that can be held in the main hearth 41 is determined in advance by experiments or the like. Determined by.
Imax> Ie… (3)
Imax>Imin> Io… (4)
τa ≦ 10 / B ... (5)
τb ≦ 10 / B ... (6)

  Based on the above equations (1) to (6), the maximum current value Imax and the minimum current value Imin of the supply current C with respect to the film formation rate Tr1 are determined. In the end, fine adjustment may be made by experiment.

For example, when the film diameter Ma of the film formation material Ma is 30 mm and the conveyance speed B is 15 mm / sec, a supply current of 150 A is used for the film formation speed Trs of 100 nm / min. By substituting these values into the equation (1), the current value I1 of the supply current corresponding to the target film formation rate Tr1 (= 50 nm / min) is calculated.
I1 = (50/100) × 150 = 75 [A]

  Then, each value is selected so that I1 = 75A = (τa × Imax + τb × Imin) / (τa + τb). For example, if Imax = 150 A (Imax> Ie = 100 A, current value at which jumping starts to occur), Imin = 30 A (Imin> Io, current value at which the plasma beam Pb disappears), and τa = 0.2 sec, then τb = 0.33 sec. Finally, the actual discharge is performed under these conditions, and the conditions are determined by finely adjusting the push-up speed of the film forming material Ma at the time of continuous time τa, continuous time τb, and maximum current value Imax.

  By determining the maximum current value Imax, its duration τa, the minimum current value Imin, and its duration τb as described above, it is possible to increase the deposition rate corresponding to the discharge at a constant current value 75A (<Ie: 100A). When the time discharge is continued, the discharge that does not occur even if the operation is performed for a long time can be continued even though the remaining is generated. It should be noted that by setting the maximum current value Imax to be larger than the current value Ie at which jumping starts to occur, it is possible to maintain a discharge that does not cause jumping.

  In addition, if the discharge disappears in the middle, it is necessary to reignite, so that continuous discharge cannot be continued. That is, once the plasma beam Pb disappears in the plasma generator 2, the power source 3 cannot be ignited again, and another high voltage low current power source is required. Once the plasma beam Pb disappears, it takes time for re-ignition (usually about several minutes), and continuous film formation cannot be maintained. Therefore, by setting the minimum current value Imin to be larger than the current value Io at which the plasma beam Pb disappears, it is possible to prevent the plasma beam Pb from disappearing for each pulse, and to maintain continuous film formation. It becomes.

  DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus, 2 ... Plasma generator, 3 ... Power supply, 4 ... Main anode, 10 ... Vacuum container (chamber), 11 ... Substrate (film formation object), C ... Supply current, Ma ... Film-forming material, Mb: film forming material particles (particles), Pb: plasma beam.

Claims (4)

A film forming apparatus for forming a film by heating a film forming material with a plasma beam in a chamber and attaching particles evaporated from the film forming material to an object to be formed,
A plasma generator for generating the plasma beam;
A main anode for holding the film forming material and guiding the plasma beam;
A power supply for supplying a pulsed current to the plasma generator and the main anode ;
With
The current has a maximum current value and a minimum current value alternately;
The minimum current value is a current value larger than a current value at which the plasma beam disappears in the plasma generator and smaller than the maximum current value,
The plasma generator generates a plasma beam that is incident on the main anode or incident on the deposition material based on the maximum current value and the minimum current value of the current supplied from the power source. apparatus. The film forming apparatus according to claim 1 , wherein the maximum current value is equal to or greater than a current value at which the film deposition material does not fly. The film forming apparatus according to claim 1 , wherein the power supply supplies a current having the maximum current value and the minimum current value periodically to the plasma generator. Before Symbol maximum current value, the film forming apparatus according to claim 1 which is determined according to the size of the film-forming material capable of holding the main anode.

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