Negative ion generator

Abstract

To provide a negative ion generator that can appropriately irradiate negative ions regardless of the substrate material. [Solution] The negative ion generator 1 includes a negative ion generation unit 4 that generates negative ions by generating plasma P in a chamber 2. Therefore, after the negative ion generation unit 4 stops generating plasma P, negative ions can be irradiated onto the substrate 11. Here, the negative ion generator 1 is positioned in the chamber 2 opposite the object placement unit 3 on which the substrate 11 is placed, and includes an electrode 70 that guides negative ions to the object placement unit 3 by forming a potential gradient. Therefore, the electrode 70 can guide negative ions toward the substrate 11 placed on the object placement unit 3 by the potential gradient. Therefore, even if the material of the substrate 11 is an insulator or a high-resistance material and it is difficult to apply a bias voltage, the electrode 70 can sufficiently irradiate the object with negative ions.

Description

Technical Field

[0001] The present invention relates to a negative ion generation device.

Background Art

[0002] Conventionally, as a negative ion generation device, the one described in Patent Document 1 is known. This negative ion generation device includes a gas supply unit that supplies a gas serving as a raw material for negative ions into a chamber, and a negative ion generation unit that generates negative ions by generating plasma in the chamber. The negative ion generation unit irradiates the target object with the negative ions generated in the chamber by the plasma. The negative ion generation device irradiates the target object with negative ions at the timing when the plasma is turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the negative ion generation device as described above, negative ions were guided to the substrate by applying a positive bias voltage to the substrate. However, as the substrate to be irradiated, an insulating substrate, a high-resistance substrate, etc. may be adopted. The negative ion generation device has a problem that it cannot sufficiently apply a bias voltage to the irradiation surface of such a substrate and cannot sufficiently irradiate negative ions.

[0005] Therefore, an object of the present invention is to provide a negative ion generation device that can appropriately irradiate negative ions regardless of the material of the target object.

Means for Solving the Problems

[0006] To solve the above problems, the negative ion generating apparatus according to the present invention is a negative ion generating apparatus that generates negative ions and irradiates an object with them, comprising a chamber in which negative ions are generated internally, and a negative ion generating unit that generates negative ions by generating plasma in the chamber, and guides the negative ions to the object placement unit by forming a potential gradient at a position opposite to the object placement unit in which the object is placed.

[0007] The negative ion generator according to the present invention includes a negative ion generation unit that generates negative ions by generating plasma in a chamber. Therefore, after the negative ion generation unit stops generating plasma, it becomes possible to irradiate the target object with negative ions. Here, the negative ion generator guides the negative ions to the target object placement unit by forming a potential gradient at a position opposite the target object placement unit where the target object is placed. Therefore, the negative ion generator can guide negative ions toward the target object placed on the target object placement unit by the potential gradient. Therefore, even if the material of the target object is an insulator or a high-resistance material and it is difficult to apply a bias voltage, the negative ion generator can sufficiently irradiate the target object with negative ions. Thus, negative ions can be appropriately irradiated regardless of the material of the target object.

[0008] The negative ion generator further includes an electrode positioned in the chamber opposite the object placement section where the object is placed, which guides negative ions to the object placement section by forming a potential gradient. In this case, the potential gradient can be easily formed by placing the electrode inside the chamber.

[0009] The electrodes may consist of a first electrode and a second electrode, in that order from the side where the object is placed. In this case, creating a potential difference between the first electrode and the second electrode makes it easier to form a potential gradient.

[0010] The potential of the second electrode may be the same as the plasma potential. Compared to the case where the potential of the second electrode is higher than the plasma potential, a larger potential gradient can be formed between it and the first electrode.

[0011] The potential of the first electrode may be the same as the potential of the object placement area. Compared to the case where the potential of the first electrode is lower than the potential of the object placement area, a larger potential gradient can be formed between it and the second electrode.

[0012] The distance between the electrode and the object placement area may be such that the potential is parallel to the potential between the object and the electrode. In this case, negative ions can be effectively guided to the object.

[0013] The negative ion generator may further include a magnetic field generating unit that forms a magnetic field along the mounting surface of the object placement unit. In this case, the magnetic field of the magnetic field generating unit can guide electrons so as not to irradiate the object. Therefore, the magnetic field generating unit can suppress the irradiation of electrons to the object.

[0014] The electrode may be made of a mesh material. In this case, the electrode can form a potential gradient while allowing negative ions toward the object to pass through.

[0015] The width of the through-holes in the mesh member may be the distance at which the potential is connected between the metal parts flanking the through-holes. In this case, negative ions can be effectively guided to the target object. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a negative ion generator that can appropriately irradiate negative ions regardless of the substrate material. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view showing the configuration of the negative ion generator according to this embodiment. [Figure 2] This graph shows the ON / OFF timing of plasma P and the arrival of positive and negative ions at the target object. [Figure 3] This is a schematic diagram illustrating the relationship between the substrate, extraction electrode, plasma electrode, and potential. [Figure 4] This figure shows an example of an electrode mesh component.

Best Mode for Carrying Out the Invention

[0018] Hereinafter, a negative ion generation device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted.

[0019] First, referring to FIG. 1, the configuration of the negative ion generation device according to an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing the configuration of the negative ion generation device according to the present embodiment. For convenience of explanation, an XYZ coordinate system is shown in FIG. 1. The X-axis direction is the thickness direction of the substrate, which is the object. The Y-axis direction and the Z-axis direction are directions orthogonal to the X-axis direction and orthogonal to each other.

[0020] As shown in FIG. 1, the negative ion generation device 1 of the present embodiment includes a chamber 2, an object placement unit 3, a negative ion generation unit 4, a gas supply unit 6, a circuit unit 7, a voltage application unit 8, and a control unit 50.

[0021] The chamber 2 is a member for housing the substrate 11 (object) and performing irradiation treatment with negative ions. The chamber is a member in which negative ions are generated inside. The chamber 2 is made of a conductive material and is connected to the ground potential.

[0022] The chamber 2 includes a pair of wall portions and facing each other in the X-axis direction, a pair of wall portions and facing each other in the Y-axis direction, and a pair of wall portions (not shown) facing each other in the Z-axis direction. The wall portion is arranged on the negative side in the X-axis direction, and the wall portion is arranged on the positive side. The wall portion is arranged on the negative side in the Y-axis direction, and the wall portion is arranged on the positive side.

[0023] The object placement section 3 is used to position the substrate 11, which will be irradiated with negative ions. The object placement section 3 is provided on the wall portion 2a of the chamber 2. The object placement section 3 comprises a mounting member 12 and a connecting member 13. The mounting member 12 and the connecting member 13 are made of conductive material. The mounting member 12 is a member for mounting the substrate 11 on its mounting surface. The mounting member 12 is attached to the wall portion 2a and positioned within the internal space of the chamber 2. The mounting surface is a plane that extends perpendicular to the X-axis direction. As a result, the substrate 11 is placed on the mounting surface so as to be perpendicular to the X-axis direction and parallel to the ZY plane. The connecting member 13 is a member that electrically connects the mounting member 12 and the voltage application section 8. The connecting member 13 extends through the wall portion 2a to the outside of the chamber 2. The mounting member 12 and the connecting member 13 are insulated from the chamber 2.

[0024] In this embodiment, an insulating material may be used as the substrate 11 to be irradiated with negative ions. Examples of insulating substrates 11 include glass substrates, fine ceramics such as SiO2, SiON, AlN, Al2O3, and Si3N4, phenolic resins, epoxy resins, polyimide resins, resin-containing substrates such as Teflon® and fluororesins, polyimide, and flexible substrate materials such as PET. In addition, metal plates, conductive substrates, and semiconductors can also be used as the substrate 11.

[0025] Next, the configuration of the negative ion generation unit 4 will be described in detail. The negative ion generation unit 4 generates plasma and electrons within the chamber 2, thereby generating negative ions and radicals. The negative ion generation unit 4 includes a plasma gun 14 and an anode 16.

[0026] The plasma gun 14 is, for example, a pressure gradient type plasma gun, and its main body is provided on the wall 2c of the chamber 2 and connected to the internal space of the chamber 2. The plasma gun 14 has a gas supply unit (not shown) and supplies noble gases such as Ar and He to generate plasma. The plasma gun 14 generates plasma P in the chamber 2. The plasma P generated in the plasma gun 14 is emitted in a beam shape from the plasma port into the internal space of the chamber 2. As a result, plasma P is generated in the internal space of the chamber 2.

[0027] The anode 16 is a mechanism that guides the plasma P from the plasma gun to a desired position. The anode 16 is a mechanism that has an electromagnet for guiding the plasma P. The anode 16 is provided on the wall portion 2d of the chamber and is positioned opposite the plasma gun 14 in the Y-axis direction. As a result, the plasma P is emitted from the plasma gun 14, spreads out in the internal space of the chamber 2 while moving toward the positive side in the Y-axis direction, and then converges and is guided to the anode 16. Note that the positional relationship between the plasma gun 14 and the anode 16 is not limited to the above, and any positional relationship may be adopted as long as negative ions can be generated.

[0028] The gas supply unit 6 is located outside the chamber 2. The gas supply unit 6 supplies gas into the chamber 2 through a gas supply port 26 formed in the wall portion 2d. The gas supply port 26 is formed between the negative ion generation unit 4 and the object placement unit 3. Here, the gas supply port 26 is formed between the negative end of the wall portion 2d in the X-axis direction and the anode 16. However, the position of the gas supply port 26 is not particularly limited. The gas supply unit 6 supplies a gas that serves as the raw material for negative ions. For example, O - O2 and NH4 are the raw materials for negative ions. - NH2, NH4, and others are used as raw materials for negative ions of nitrides such as C - Ya Si - C2H6 and SiH4, which are used as raw materials for negative ions, are employed. Note that the gas also includes noble gases such as Ar.

[0029] The circuit section 7 includes a variable power supply 30, a first wiring 31, a second wiring 32, resistors R1 to R3, and a switch SW1. The variable power supply 30 applies a negative voltage to the cathode 21 and a positive voltage to the anode 16 of the plasma gun 14, with the chamber 2, which is at ground potential, in between. This generates a potential difference between the cathode 21 and anode 16 of the plasma gun 14. The first wiring 31 electrically connects the cathode 21 of the plasma gun 14 to the negative potential side of the variable power supply 30. The second wiring 32 electrically connects the anode 16 to the positive potential side of the variable power supply 30. Resistor R1 is connected in series between the first intermediate electrode 22 and the variable power supply 30. Resistor R2 is connected in series between the second intermediate electrode 23 and the variable power supply 30. Resistor R3 is connected in series between the chamber 2 and the variable power supply 30. Switch SW1 is switched between ON and OFF states by receiving a command signal from the control unit 50. Switch SW1 is connected in parallel with resistor R2. Switch SW1 is in the OFF state when generating plasma P. On the other hand, switch SW1 is in the ON state when stopping plasma P.

[0030] The voltage application unit 8 applies a bias voltage to the substrate 11 and the mounting member 12. The voltage application unit 8 includes a power supply 36 that applies a bias voltage to the substrate 11 and the mounting member 12, a third wiring 37 that connects the power supply 36 to the object placement unit 3, and a switch SW2 provided on the third wiring 37. The power supply 36 applies a positive voltage as the bias voltage. One end of the third wiring 37 is connected to the positive potential side of the power supply 36, and the other end is connected to the connecting member 13. As a result, the third wiring 37 electrically connects the power supply 36 and the substrate 11 via the connecting member 13 and the mounting member 12. The ON / OFF state of the switch SW2 is switched by the control unit 50.

[0031] The control unit 50 is a device that controls the entire negative ion generator 1 and is equipped with an electronic control unit that comprehensively manages the entire device. The control unit 50 is an electronic control unit that has a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), CAN (Controller Area Network) communication circuit, etc. The control unit 50 realizes various functions, for example, by loading a program stored in ROM into RAM and executing the program loaded into RAM with the CPU. The control unit 50 may be composed of multiple electronic units.

[0032] The control unit 50 is located outside the chamber 2. The control unit 50 includes a gas supply control unit 51 that controls the gas supply by the gas supply unit 6, a plasma control unit 52 that controls the generation of plasma P by the negative ion generation unit 4, and a voltage control unit 53 that controls the application of bias voltage by the voltage application unit 8. The control unit 50 controls the system to perform intermittent operation, repeatedly generating and stopping plasma P.

[0033] When switch SW1 is OFF, controlled by the plasma control unit 52, plasma P is emitted from the plasma gun 14 into the chamber 2, thus generating plasma P within the chamber 2. Plasma P consists of neutral particles, positive ions, negative ions (if a negative gas such as oxygen gas is present), and electrons. When switch SW1 is ON, controlled by the plasma control unit 52, plasma P is not emitted from the plasma gun 14 into the chamber 2, causing a rapid decrease in the electron temperature of the plasma P within the chamber 2. As a result, electrons are more easily attached to the gas particles supplied into the chamber 2. This efficiently generates negative ions in the generation chamber 10b. The voltage control unit 53 controls the voltage application unit 8 to apply a positive bias voltage to the substrate 11 when the plasma P is stopped. This guides negative ions in the chamber 2 to the substrate 11, and the negative ions irradiate the substrate 11.

[0034] Figure 2 is a graph showing the ON / OFF timing of plasma P and the arrival of positive and negative ions on the target object. In the figure, the region labeled "ON" indicates the generation state of plasma P, and the region labeled "OFF" indicates the stopped state of plasma P. Plasma P is stopped at time t1. During plasma P generation, many positive ions are generated. At this time, many electrons are also generated in chamber 2. When plasma P is stopped, the number of positive ions decreases rapidly. At this time, the number of electrons also decreases. Negative ions increase rapidly from time t2, a predetermined time after plasma P has stopped, and peak at time t3. Note that both positive ions and electrons decrease after plasma P stops, and around time t3, the amount of positive ions becomes equal to the amount of negative ions, and there are almost no electrons left.

[0035] Next, the structure around the object placement section 3 will be described in more detail. As shown in Figure 1, the negative ion generator 1 includes an electrode 70 and a magnetic field forming section 80.

[0036] The electrode 70 is positioned within the chamber 2, facing the object placement section 3 and the substrate 11, and is a component that guides negative ions to the object placement section 3 and the substrate 11 by forming a potential gradient. Within the internal space of the chamber 2, the space where plasma P exists when irradiated with plasma P is defined as the plasma space PSP. Within the internal space of the chamber 2, the electrode 70 is positioned on the object placement section 3 side, i.e., on the negative side in the X-axis direction, relative to the plasma space PSP.

[0037] The negative ion generator 1 has electrodes 70, consisting of an extraction electrode 71 (first electrode) and a plasma electrode 72 (second electrode), in order from the object placement section 3 side. The extraction electrode 71 and the plasma electrode 72 are arranged to spread out in the YZ plane, parallel to the mounting surface of the mounting member 12 and the substrate 11. The extraction electrode 71 is positioned at a location spaced apart from the mounting surface of the mounting member 12 and the substrate 11 in the positive direction of the X axis. The plasma electrode 72 is positioned at a location spaced apart from the extraction electrode 71 in the positive direction of the X axis. Preferably, the extraction electrode 71 and the plasma electrode 72 have a width sufficient to cover at least the substrate 11 when viewed from the positive side to the negative side in the X axis.

[0038] The lead electrode 71 is connected to the power supply 36 via a third wire 37. The third wire 37 extending from the power supply 36 branches into wires 37a and 37b downstream of the switch SW2. Wire 37a is connected to the mounting member 12, and wire 37b is connected to the lead electrode 71. The plasma electrode 72 is connected to the power supply 39 via wire 38. Power supply 39 is a different power supply from power supply 36.

[0039] Figure 3 is a schematic diagram illustrating the relationship between the substrate 11, the extraction electrode 71, the plasma electrode 72, and the potential. The "potential distribution" diagram in Figure 3 is a graph showing the relationship between the position in the X-axis direction and the potential. The vertical axis of the "potential distribution" diagram indicates the position in the X-axis direction. The position where the plasma electrode 72 is placed is indicated as "plasma electrode," the position where the extraction electrode 71 is placed is indicated as "extraction electrode," and the position where the substrate 11 is placed is indicated as "substrate position." The "after plasma OFF" diagram shows the situation when the plasma P is stopped. The "during plasma ON" diagram shows the situation when the plasma P is irradiating.

[0040] As shown in the "Potential Distribution" graph in Figure 3, the potential of the plasma electrode 72 is the same as the potential of the plasma P. Here, "same" does not only mean a perfect match, but also allows for a difference in value within the margin of error of the potential. If the potential of the plasma P is the plasma potential V1, then the potential of the plasma electrode 72 is set to the plasma potential V1. Therefore, the potential on the plasma space PSP side of the plasma electrode 72 is approximately constant at the plasma potential V1 (see "P1" in the figure). The potential of the extraction electrode 71 is the same as the potential of the object placement section 3 and the substrate 11. Here, "same" does not only mean a perfect match, but also allows for a difference in value within the margin of error of the potential. If the potential of the substrate 11 and the object placement section 3 is the extraction potential V2, then the potential of the extraction electrode 71 is set to the extraction potential V2. Therefore, the potential between the extraction electrode 71 and the substrate 11 is approximately constant at the extraction potential V2 (see "P2" in the figure). The extraction potential V2 is higher than the plasma potential V1.

[0041] The potential between the plasma electrode 72 and the extraction electrode 71 rises from the plasma potential V1 to the extraction potential V2. Therefore, a potential gradient is formed between the plasma electrode 72 and the extraction electrode 71 (see "P3" in the figure). As a result, the electrode 70 can guide negative ions to the object placement section 3 and the substrate 11 by forming a potential gradient.

[0042] The plasma potential V1 is not particularly limited, but may be set to, for example, 0 to 20V. The extraction potential V2 is not particularly limited, but may be set to, for example, 0 to 100V. The distance between the plasma electrode 72 and the extraction electrode 71 is defined as the inter-electrode distance L1. The distance between the extraction electrode 71 and the substrate 11 is defined as the inter-electrode distance L2. The inter-electrode distance L1 is set to a distance sufficient to form a potential gradient in the space between the plasma electrode 72 and the extraction electrode 71. The inter-electrode distance L1 may be set to, for example, 1 to 10 mm. The inter-electrode distance L2 is the distance over which the potential is connected in a parallel direction between the substrate 11 and the electrode 70 (extraction electrode 71). The parallel direction is the direction in which the substrate 11 and the electrode 70 are aligned, which corresponds to the X-axis direction. That is, the inter-electrode distance L2 is set to a distance over which the potential in the space between the extraction electrode 71 and the substrate 11 is maintained at the extraction potential V2. The inter-electrode distance L2 may be set to, for example, 1 to 10 mm. Since the thickness of the substrate 11 may be changed, the distance between the lead-out electrode 71 and the object placement section 3 is adjusted to take such changes in thickness into consideration.

[0043] As shown in Figure 4, the electrode 70 is composed of a mesh member 90. That is, the extraction electrode 71 and the plasma electrode 72 are composed of a mesh member 90. The mesh member 90 is a plate-shaped member and is made of a conductive material. As the material for the mesh member 90, a metal having an oxidation-resistant surface such as Au or Pt plating may be used. The mesh member 90 is composed of a plate-shaped member having a plurality of through holes 91. The through holes 91 have a predetermined shape and are arranged at a predetermined pitch. For example, the mesh member 90 shown in Figure 4(a) has rectangular through holes 91. The mesh member 90 shown in Figure 4(b) has circular through holes 91. The mesh member 90 shown in Figure 4(c) has hexagonal through holes 91. The mesh member 90 shown in Figures 4(d) and 4(e) has rectangular through holes 91. The size of the through-hole 91 and the width of the metal portion of the plate-shaped member are preferably set to a size that allows negative ions to pass through well and to form a desired potential. The width (maximum width) of the through-hole 91 in Figures 4(a), (b), and (c) may be set to 1 mm or less. The width of the metal portion between the through-holes 91 may be set to 1 mm or less. The short side of the through-hole 91 in Figures 4(d) and (e) may be set to 1 mm or less, and the long side may be set to about 10 mm. The thickness of the mesh member 90 may be set to about 0.5 to 1.5 mm from the viewpoint of preventing deflection, etc. Note that Figure 4 is merely an example of the configuration of the mesh member 90, and a mesh member with other configurations may be used. For example, the width (maximum width) of the through-hole 91 in Figures 4(a), (b), and (c), that is, the spacing of the metal portions in the mesh member 90, is set to a distance such that the potential connects between the metal portions that sandwich the through-hole 91. If the spacing between the metal parts of the mesh member 90 is too wide, an electric potential cannot be formed in the internal space of the through-holes 91 of the mesh member 90, making it difficult to guide ions.

[0044] Returning to Figure 1, the magnetic field forming section 80 is a mechanism for forming a magnetic field. The magnetic field forming section 80 is equipped with magnetic field generators 81 located on the positive and negative sides in the Y-axis direction, respectively, sandwiching the chamber 2 at the negative ends in the X-axis direction of the wall sections 2c and 2d. The magnetic field forming section 80 forms a magnetic field in a direction along the mounting surface of the mounting member 12. That is, the magnetic field forming section 80 forms a magnetic field in a direction along the irradiated surface of the substrate 11. The direction along the mounting surface and the irradiated surface means a direction that is approximately parallel to these surfaces. Here, the magnetic flux B generated by the magnetic field generator 81 extends approximately parallel to the Y-axis direction.

[0045] Next, with reference to Figure 3, the irradiation patterns of negative ions and the like to the substrate 11 will be described. It is assumed that the potential distribution shown in "Potential Distribution" is maintained whether the plasma P is ON or OFF. As shown in the "Plasma OFF" diagram of Figure 3, when the plasma P is OFF, negative ions 100, positive ions 101, and radicals 102 exist in the plasma space PSP. The negative ions 100 attracted to the substrate 11 are accelerated toward the substrate 11 by the potential gradient formed between the plasma electrode 72 and the extraction electrode 71. As a result, the negative ions 100 are irradiated onto the substrate 11. The positive ions are prevented from moving toward the substrate 11 by the potential gradient formed between the plasma electrode 72 and the extraction electrode 71. The radicals 102 are irradiated onto the substrate 11 without being affected by the potential gradient. As shown in the "Plasma ON" diagram of Figure 3, when the plasma P is ON, negative ions 100, positive ions 101, radicals 102, and electrons exist in the plasma space PSP. Negative ions 100, positive ions 101, and radicals 102 behave similarly to those after the plasma is turned off. Electrons 103 heading toward the substrate 11 are guided laterally by the transverse magnetic field generated by the magnetic field forming unit 80 (see Figure 1), thus preventing them from irradiating the substrate 11.

[0046] Next, the operation and effects of the negative ion generator 1 according to this embodiment will be described.

[0047] The negative ion generator 1 according to this embodiment includes a negative ion generation unit 4 that generates negative ions by generating plasma P in a chamber 2. Therefore, after the negative ion generation unit 4 stops generating plasma P, negative ions can be irradiated onto the substrate 11. Here, the negative ion generator 1 guides the negative ions to the object placement unit 3 by forming a potential gradient at a position opposite to the object placement unit 3 where the substrate 11 is placed. Therefore, the negative ion generator 1 can guide negative ions toward the substrate 11 placed on the object placement unit 3 by the potential gradient. Therefore, even if the material of the substrate 11 is an insulator or a high-resistance material and it is difficult to apply a bias voltage, the negative ion generator can sufficiently irradiate the object with negative ions. Thus, negative ions can be appropriately irradiated regardless of the material of the substrate 11.

[0048] The negative ion generator 1 may further include an electrode 70 positioned in the chamber 2 opposite the object placement section 3 where the substrate 11 is placed, which guides negative ions to the object placement section 3 by forming a potential gradient. In this case, the potential gradient can be easily formed by providing the electrode 70 inside the chamber 2.

[0049] The electrode 70 may include an extraction electrode 71 and a plasma electrode 72, in that order from the object placement section 3 side. In this case, a potential difference is created between the extraction electrode 71 and the plasma electrode 72, making it easier to form a potential gradient.

[0050] The potential of the plasma electrode 72 may be the same as the potential of the plasma P. When the potential of the plasma electrode 72 is higher than the potential of the plasma P, the potential difference between the plasma electrode 72 and the extraction electrode 71 will be smaller than the fluff shown in Figure 3. Therefore, by setting the potential of the plasma electrode 72 to be the same as the potential of the plasma P, a larger potential gradient can be formed between it and the extraction electrode 71 compared to the case where the potential of the plasma electrode 72 is higher than the potential of the plasma P.

[0051] The potential of the extraction electrode 71 may be the same as the potential of the object placement section 3. If the potential of the extraction electrode 71 is lower than the potential of the object placement section 3, the potential difference between the plasma electrode 72 and the extraction electrode 71 will be smaller than the fluff shown in Figure 3. Therefore, by setting the potential of the extraction electrode 71 to be the same as the potential of the object placement section 3, a larger potential gradient can be formed between it and the second electrode compared to the case where the potential of the extraction electrode 71 is lower than the potential of the object placement section 3.

[0052] The inter-electrode distance L2 between the electrode 70 and the object placement section 3 may be a distance at which the potential is connected in a parallel direction between the substrate 11 and the electrode 70. In this case, negative ions can be effectively guided to the substrate 11.

[0053] The negative ion generator 1 may further include a magnetic field forming unit 80 that forms a magnetic field along the mounting surface of the object placement unit 3. In this case, the magnetic field of the magnetic field forming unit 80 can guide electrons so as not to irradiate the object. Therefore, the magnetic field forming unit 80 can suppress electrons from irradiating the substrate 11.

[0054] The electrode 70 may be made of a mesh member 90. In this case, the electrode 70 can form a potential gradient while allowing negative ions toward the substrate 11 to pass through.

[0055] The width of the through-hole 91 in the mesh member 90 may be the distance at which the potential connects the metal parts flanking the through-hole 91. In this case, negative ions can be effectively guided to the substrate 11.

[0056] The present invention is not limited to the embodiments described above.

[0057] For example, in the above embodiment, the plasma gun 14 was a pressure gradient type plasma gun, but the plasma gun 14 is not limited to a pressure gradient type as long as it can generate plasma in the chamber 2.

[0058] Furthermore, in the above embodiment, only one set of plasma gun 14 and anode 16 for guiding plasma P was provided in the chamber 2, but multiple sets may be provided. Also, plasma P may be supplied to a single location from multiple plasma guns 14.

[0059] In the above embodiment, a pair of plasma electrodes 72 and an extraction electrode 71 were used as the electrode 70, but the configuration of the electrode 70 is not particularly limited as long as it can form a potential gradient. [Explanation of Symbols]

[0060] 1...Negative ion generator, 2...Chamber, 3...Object placement section, 4...Negative ion generation section, 11...Substrate (object), 70...Electrode, 71...Extraction electrode (first electrode), 72...Plasma electrode (second electrode), 80...Magnetic field formation section.

Claims

1. A negative ion generator that generates negative ions and irradiates an object with them, A chamber in which the negative ions are generated internally, The system comprises a negative ion generation unit that generates negative ions by generating plasma within the chamber, A negative ion generating device that guides the negative ions to the object placement section by forming a potential gradient at a position opposite to the object placement section where the object is placed.

2. The negative ion generating apparatus according to claim 1, further comprising an electrode positioned in the chamber opposite to an object placement section where the object is placed, and which forms a potential gradient to guide the negative ions to the object placement section.

3. The negative ion generating apparatus according to claim 1, wherein the electrodes include a first electrode and a second electrode in order from the object placement side.

4. The negative ion generating apparatus according to claim 2, wherein the potential of the second electrode is the same as the potential of the plasma.

5. The negative ion generating apparatus according to claim 2, wherein the potential of the first electrode is the same as the potential of the object placement section.

6. The negative ion generating apparatus according to claim 2, wherein the distance between the electrode and the object placement section is the distance over which the potential is connected in a parallel direction between the object and the electrode.

7. The negative ion generating apparatus according to claim 1, further comprising a magnetic field forming unit that forms a magnetic field along the mounting surface of the object placement unit.

8. The negative ion generating apparatus according to claim 1, wherein the electrode is composed of a mesh member.

9. The negative ion generating apparatus according to claim 8, wherein the width of the through-hole in the mesh member is the distance at which the potential connects between the metal parts that straddle the through-hole.

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