JP7412074B2 - Negative ion irradiation device and control method for negative ion irradiation device - Google Patents

Description

The present invention relates to a negative ion irradiation device and a method of controlling the negative ion irradiation device.

Conventionally, a compound semiconductor described in Patent Document 1 has been known. A single crystal substrate constituting such a compound semiconductor has many crystal defects. Patent Document 1 attempts to reduce crystal defects in a single crystal substrate by devising a manufacturing method.

JP2014-22711A

However, when manufacturing a single crystal substrate, it is difficult to prevent crystal defects from occurring even if the manufacturing method is devised. Furthermore, when a crystal defect occurs in a single crystal substrate, there is no practical method for filling the crystal defect. Therefore, single-crystal substrates with crystal defects have been used as they are. The grade (quality) of a single crystal substrate is determined according to the amount of crystal defects, and the use is determined according to the grade. Therefore, there is a problem in that the number of single crystal substrates that can be used for compound semiconductors is limited, resulting in a decrease in the manufacturing efficiency of compound semiconductors. On the other hand, when a low-grade single crystal substrate is used as a compound semiconductor, there is a problem that the quality of the compound semiconductor deteriorates.

Therefore, an object of the present invention is to provide a negative ion irradiation device and a method for controlling the negative ion irradiation device that can improve the manufacturing efficiency and quality of compound semiconductors.

In order to solve the above problems, a negative ion irradiation device according to the present invention is a negative ion irradiation device that irradiates a compound semiconductor with negative ions, and includes a chamber in which negative ions are generated and a compound semiconductor. A gas supply unit that supplies a gas containing the same element as the ions, a plasma generation unit that generates plasma and electrons in the chamber, a placement unit that arranges the compound semiconductor, and a control unit that controls the negative ion irradiation device. , the control unit controls the gas supply unit to supply gas into the chamber, controls the plasma generation unit to generate plasma and electrons in the chamber, and stops the generation of plasma. This generates negative ions using electrons and gas, and irradiates the compound semiconductor with the negative ions.

In the negative ion irradiation device according to the present invention, the control section controls the gas supply section to supply gas into the chamber. The gas supply unit supplies a gas containing the same element as ions forming the compound semiconductor. Therefore, the same element as the ions forming the compound semiconductor is present in the chamber. The control unit controls the plasma generation unit to generate plasma and electrons in the chamber, and stops the generation of plasma to generate negative ions from the electrons and gas, and converts the negative ions into a compound. Irradiates the semiconductor. As a result, the compound semiconductor is irradiated with negative ions of the same element as the ions forming the compound semiconductor. Thereby, the negative ions enter the crystal defects derived from the anions in the compound semiconductor, thereby making it possible to fill the crystal defects. Since crystal defects in the compound semiconductor can be filled in this way, the quality of the compound semiconductor can be improved. In addition, even if the grade of a compound semiconductor is not sufficient before negative ion irradiation, the quality can be improved by negative ion irradiation, reducing the need to select the grade of single crystal substrates in advance. can. With the above, manufacturing efficiency and quality of compound semiconductors can be improved.

A method for controlling a negative ion irradiation device according to the present invention is a method for controlling a negative ion irradiation device that irradiates negative ions to a compound semiconductor, and the negative ion irradiation device includes a chamber in which negative ions are generated; A gas supply unit that supplies a gas containing the same element as the ions forming the compound semiconductor, a plasma generation unit that generates plasma and electrons in the chamber, a placement unit that arranges the compound semiconductor, and control of the negative ion irradiation device. and a gas supply step in which the control unit controls the gas supply unit to supply gas into the chamber, and the control unit controls the plasma generation unit to supply plasma and electrons into the chamber. and a negative ion irradiation step of generating negative ions from electrons and gas by stopping plasma generation, and irradiating the compound semiconductor with the negative ions.

According to the method for controlling a negative ion irradiation device according to the present invention, the same functions and effects as those of the above-described negative ion irradiation device can be obtained.

According to the present invention, it is possible to provide a negative ion irradiation device and a method for controlling the negative ion irradiation device that can improve the manufacturing efficiency and quality of compound semiconductors.

1 is a schematic cross-sectional view showing the configuration of a negative ion irradiation device according to an embodiment of the present invention, and a diagram showing an operating state during plasma generation. FIG. 2 is a schematic cross-sectional view showing the configuration of the negative ion irradiation device of FIG. 1, and is a diagram showing an operating state when plasma is stopped. It is a flowchart which shows the control method of the negative ion irradiation apparatus based on this embodiment. FIG. 2 is a diagram schematically showing how a compound semiconductor is irradiated with negative ions. As a comparative example, it is a diagram schematically showing the situation when positive ions are implanted into a compound semiconductor. FIG. 2 is a diagram schematically showing a state when negative ions are implanted into a compound semiconductor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A negative ion irradiation device according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In addition, in the description of the drawings, the same elements are given the same reference numerals, and redundant description will be omitted.

First, with reference to FIGS. 1 and 2, the configuration of a negative ion irradiation apparatus according to an embodiment of the present invention will be described. 1 and 2 are schematic cross-sectional views showing the configuration of a negative ion irradiation device according to this embodiment. FIG. 1 shows the operating state when plasma is generated, and FIG. 2 shows the operating state when plasma is stopped.

As shown in FIGS. 1 and 2, the negative ion irradiation apparatus 1 of this embodiment is an apparatus in which a film forming technique used in so-called ion plating is applied to negative ion irradiation. Note that for convenience of explanation, an XYZ coordinate system is shown in FIGS. 1 and 2. The Y-axis direction is a direction in which a compound semiconductor, which will be described later, is transported. The X-axis direction is the thickness direction of the compound semiconductor. The Z-axis direction is a direction perpendicular to the Y-axis direction and the X-axis direction.

The negative ion irradiation device 1 may be a so-called horizontal negative ion irradiation device in which the compound semiconductor 11 is placed in the vacuum chamber 10 and transported so that the thickness direction of the compound semiconductor 11 is substantially vertical. In this case, the Z-axis and Y-axis directions are horizontal, and the X-axis direction is vertical and the plate thickness direction. Note that the negative ion irradiation device 1 is configured to hold the compound semiconductor 11 upright or in a tilted state from an upright state so that the thickness direction of the compound semiconductor 11 is in the horizontal direction (X-axis direction in FIGS. 1 and 2). It may be a so-called vertical negative ion irradiation device in which the compound semiconductor 11 is placed in the vacuum chamber 10 and transported. In this case, the X-axis direction is a horizontal direction and the thickness direction of the compound semiconductor 11, the Y-axis direction is a horizontal direction, and the Z-axis direction is a vertical direction. A negative ion irradiation device according to an embodiment of the present invention will be described below using a horizontal negative ion irradiation device as an example.

The negative ion irradiation device 1 includes a vacuum chamber 10, a transport mechanism (arrangement section) 3, a plasma generation section 14, a gas supply section 40, a circuit section 34, a voltage application section 90, and a control section 50.

The vacuum chamber 10 is a member for accommodating a compound semiconductor 11 and performing a film forming process. The vacuum chamber 10 includes a transfer chamber 10a for transferring the compound semiconductor 11, a generation chamber 10b for generating negative ions, and a plasma port for receiving plasma P irradiated in the form of a beam from the plasma gun 7 into the vacuum chamber 10. 10c. The transfer chamber 10a, the generation chamber 10b, and the plasma port 10c communicate with each other. The transport chamber 10a is set along a predetermined transport direction (arrow A in the figure) (along the Y axis). Further, the vacuum chamber 10 is made of a conductive material and is connected to ground potential. A heating section 30 for heating the compound semiconductor 11 is provided in the transfer chamber 10a. The heating unit 30 is provided in the transport chamber 10a on the upstream side in the transport direction of the communication part with the generation chamber 10b. Therefore, the negative ions from the generation chamber 10b are irradiated onto the heated compound semiconductor 11.

The generation chamber 10b includes, as a wall portion 10W, a pair of side walls along the transport direction (arrow A), and a pair of side walls 10h and 10i along the direction (Z-axis direction) intersecting the transport direction (arrow A). It has a bottom wall 10j arranged to intersect with the X-axis direction.

The transport mechanism 3 transports the compound semiconductor holding member 16 that holds the compound semiconductor 11 in a state facing the generation chamber 10b in the transport direction (arrow A). The transport mechanism 3 functions as a placement section where the compound semiconductor 11 is placed. For example, the compound semiconductor holding member 16 is a frame that holds the outer peripheral edge of the compound semiconductor 11. The transport mechanism 3 includes a plurality of transport rollers 15 installed in the transport chamber 10a. The conveyance rollers 15 are arranged at regular intervals along the conveyance direction (arrow A), and convey the compound semiconductor holding member 16 in the conveyance direction (arrow A) while supporting it. Note that the compound semiconductor 11 is a plate-shaped substrate. The material of the compound semiconductor 11 will be described later.

Next, the configuration of the plasma generation section 14 will be explained in detail. The plasma generation unit 14 generates plasma and electrons within the vacuum chamber 10 . The plasma generation section 14 includes a plasma gun 7, a steering coil 5, and a hearth mechanism 2.

The plasma gun 7 is, for example, a pressure gradient type plasma gun, and its main body is connected to the generation chamber 10b via a plasma port 10c provided on the side wall of the generation chamber 10b. The plasma gun 7 generates plasma P within the vacuum chamber 10. The plasma P generated in the plasma gun 7 is emitted in the form of a beam from the plasma port 10c into the generation chamber 10b. As a result, plasma P is generated within the generation chamber 10b.

The plasma gun 7 has one end closed by a cathode 60. A first intermediate electrode (grid) 61 and a second intermediate electrode (grid) 62 are arranged concentrically between the cathode 60 and the plasma port 10c. An annular permanent magnet 61a for converging the plasma P is built in the first intermediate electrode 61. An electromagnetic coil 62a is also built into the second intermediate electrode 62 to converge the plasma P.

When generating negative ions, the plasma gun 7 intermittently generates plasma P within the generation chamber 10b. Specifically, the plasma gun 7 is controlled by a control unit 50, which will be described later, to intermittently generate plasma P within the generation chamber 10b. This control will be detailed in the description of the control unit 50.

The steering coil 5 is provided around the plasma port 10c to which the plasma gun is attached. The steering coil 5 guides the plasma P into the generation chamber 10b. The steering coil 5 is excited by a steering coil power source (not shown).

The Haas mechanism 2 is a mechanism that guides plasma P from a plasma gun to a desired position. The hearth mechanism 2 has a main hearth 17 and a wheel hearth 6. The main hearth 17 functions as an anode that holds a film forming material when forming a film using the negative ion irradiation device 1 . However, when generating negative ions, plasma is guided to the ring hearth 6 so that the plasma P is not guided to the film forming material. Therefore, when the negative ion irradiation device 1 performs only negative ion irradiation without forming a film, the main hearth 17 does not need to hold the film forming material. Alternatively, the Haas mechanism 2 only needs to have a configuration that is sufficient to guide the plasma P.

The ring hearth 6 is an anode having an electromagnet for inducing plasma P. The ring hearth 6 is arranged around the filling part 17a of the main hearth 17. The ring hearth 6 includes an annular coil 9, an annular permanent magnet part 20, and an annular container 12, and the coil 9 and the permanent magnet part 20 are housed in the container 12. In this embodiment, the coil 9 and the permanent magnet section 20 are installed in this order in the X negative direction when viewed from the transport mechanism 3, but the permanent magnet section 20 and the coil 9 may be installed in this order in the X negative direction.

The gas supply section 40 is arranged outside the vacuum chamber 10. The gas supply unit 40 supplies gas into the vacuum chamber 10 through a gas supply port 41 provided in the side wall (for example, the side wall 10h) of the generation chamber 10b. Specific examples of the gas will be described later.

The gas supply port 41 is preferably located near the boundary between the generation chamber 10b and the transfer chamber 10a. In this case, the gas from the gas supply unit 40 can be supplied near the boundary between the generation chamber 10b and the transfer chamber 10a, so that negative ions, which will be described later, are generated near the boundary. Therefore, the generated negative ions can be suitably injected into the compound semiconductor 11 in the transfer chamber 10a. Note that the position of the gas supply port 41 is not limited to the vicinity of the boundary between the generation chamber 10b and the transfer chamber 10a.

The circuit section 34 includes a variable power supply 80, a first wiring 71, a second wiring 72, resistors R1 to R4, and shorting switches SW1 and SW2.

The variable power supply 80 applies a negative voltage to the cathode 60 of the plasma gun 7 and a positive voltage to the main hearth 17 of the hearth mechanism 2, with the vacuum chamber 10 at ground potential interposed therebetween. Thereby, the variable power supply 80 generates a potential difference between the cathode 60 of the plasma gun 7 and the main hearth 17 of the hearth mechanism 2 .

The first wiring 71 electrically connects the cathode 60 of the plasma gun 7 to the negative potential side of the variable power source 80. The second wiring 72 electrically connects the main hearth 17 (anode) of the hearth mechanism 2 to the positive potential side of the variable power supply 80 .

The resistor R1 has one end electrically connected to the first intermediate electrode 61 of the plasma gun 7, and the other end electrically connected to the variable power source 80 via the second wiring 72. That is, the resistor R1 is connected in series between the first intermediate electrode 61 and the variable power supply 80.

The resistor R2 has one end electrically connected to the second intermediate electrode 62 of the plasma gun 7, and the other end electrically connected to the variable power supply 80 via the second wiring 72. That is, resistor R2 is connected in series between second intermediate electrode 62 and variable power supply 80.

The resistor R3 has one end electrically connected to the wall 10W of the generation chamber 10b, and the other end electrically connected to the variable power supply 80 via the second wiring 72. That is, the resistor R3 is connected in series between the wall portion 10W of the generation chamber 10b and the variable power source 80.

One end of the resistor R4 is electrically connected to the ring hearth 6, and the other end is electrically connected to the variable power source 80 via the second wiring 72. That is, the resistor R4 is connected in series between the wheel hearth 6 and the variable power source 80.

The short-circuit switches SW1 and SW2 are switching units that are switched to ON/OFF states by receiving command signals from the control unit 50, respectively.

Shorting switch SW1 is connected in parallel to resistor R2. The short-circuit switch SW1 is turned off when plasma P is generated. Thereby, the second intermediate electrode 62 and the variable power source 80 are electrically connected to each other via the resistor R2, so that it is difficult for current to flow between the second intermediate electrode 62 and the variable power source 80. As a result, plasma P from the plasma gun 7 is emitted into the vacuum chamber 10. Note that when emitting plasma P from the plasma gun 7 into the vacuum chamber 10, instead of making it difficult to make the current flow to the second intermediate electrode 62, it is made to make it difficult to make the current flow to the first intermediate electrode 61. You can. In this case, the short circuit switch SW1 is connected to the first intermediate electrode 61 side instead of the second intermediate electrode 62 side.

On the other hand, the short circuit switch SW1 is turned on when stopping the plasma P. As a result, the electrical connection between the second intermediate electrode 62 and the variable power source 80 is short-circuited, so that a current flows between the second intermediate electrode 62 and the variable power source 80. That is, a short circuit current flows through the plasma gun 7. As a result, the plasma P from the plasma gun 7 is no longer emitted into the vacuum chamber 10.

When generating negative ions, the control unit 50 switches the ON/OFF state of the short-circuit switch SW1 at predetermined intervals, so that the plasma P from the plasma gun 7 is intermittently generated within the vacuum chamber 10. That is, the short-circuit switch SW1 is a switching unit that switches between supplying and cutting off the plasma P into the vacuum chamber 10.

Shorting switch SW2 is connected in parallel to resistor R4. The ON/OFF state of the short-circuit switch SW2 is switched by the control unit 50 depending on whether the plasma P is guided to the main hearth 17 side or to the wheel hearth 6 side. When the short circuit switch SW2 is turned on, the electrical connection between the wheel hearth 6 and the variable power source 80 is short-circuited, so that it becomes easier to flow current to the wheel hearth 6 than to the main hearth 17. Thereby, the plasma P is easily guided to the ring hearth 6. On the other hand, when the short-circuit switch SW2 is turned OFF, the wheel hearth 6 and the variable power source 80 are electrically connected via the resistor R4, so it becomes easier to flow current to the main hearth 17 than to the wheel hearth 6. Plasma P is easily guided to the main hearth 17 side. Note that when negative ions are generated, the short circuit switch SW2 is kept in the ON state. When film formation is not performed using the negative ion irradiation apparatus 1, the short circuit switch SW2 may be kept in the ON state.

The voltage application unit 90 can apply a positive voltage to the compound semiconductor (object) 11 after film formation. The voltage application section 90 includes a bias circuit 35 and a contact wire 18.

The bias circuit 35 is a circuit for applying a positive bias voltage to the compound semiconductor 11 after film formation. The bias circuit 35 includes a bias power supply 27 that applies a positive bias voltage (hereinafter also simply referred to as "bias voltage") to the compound semiconductor 11, and a third wiring that electrically connects the bias power supply 27 and the contact wire 18. 73, and a short circuit switch SW3 provided on the third wiring 73. The bias power supply 27 applies a voltage signal (periodic electric signal) that is a rectangular wave that increases and decreases periodically as a bias voltage. The bias power supply 27 is configured to be able to change the frequency of the applied bias voltage under the control of the control unit 50 . The third wiring 73 has one end connected to the positive potential side of the bias power supply 27 and the other end connected to the contact wire 18 . Thereby, the third wiring 73 electrically connects the contact wire 18 and the bias power supply 27.

The shorting switch SW3 is connected in series between the contact wire 18 and the positive potential side of the bias power supply 27 via the third wiring 73. The short-circuit switch SW3 is a switching unit that switches whether or not a bias voltage is applied to the contact wire 18. The ON/OFF state of the short-circuit switch SW3 is switched by the control unit 50. The short-circuit switch SW3 is turned on at a predetermined timing when negative ions are generated. When the short-circuit switch SW3 is turned on, the contact wire 18 and the positive potential side of the bias power supply 27 are electrically connected to each other, and a bias voltage is applied to the contact wire 18.

On the other hand, the short-circuit switch SW3 is turned off at a predetermined timing when negative ions are generated. When the short-circuit switch SW3 is turned off, the contact wire 18 and the bias power supply 27 are electrically disconnected from each other, and no bias voltage is applied to the contact wire 18.

The contact wire 18 is an overhead wire that supplies power to the compound semiconductor holding member 16. The contact wire 18 is provided inside the transfer chamber 10a and extends in the transfer direction (arrow A). The contact wire 18 supplies power to the compound semiconductor holding member 16 through the power feeding brush 42 by contacting the power feeding brush 42 provided on the compound semiconductor holding member 16 . The contact wire 18 is made of, for example, stainless steel wire.

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

The control unit 50 is arranged outside the vacuum chamber 10. The control unit 50 also includes a gas supply control unit 51 that controls gas supply by the gas supply unit 40, a plasma control unit 52 that controls generation of plasma P by the plasma generation unit 14, and voltage application by a voltage application unit 90. A voltage control section 53 that controls the voltage control section 53 is provided.

The gas supply control section 51 controls the gas supply section 40 to supply gas into the generation chamber 10b. Subsequently, the plasma control section 52 of the control section 50 controls the plasma generation section 14 to intermittently generate plasma P from the plasma gun 7 within the generation chamber 10b. For example, the controller 50 switches the ON/OFF state of the short-circuit switch SW1 at predetermined intervals, so that the plasma P from the plasma gun 7 is intermittently generated within the generation chamber 10b.

When the short circuit switch SW1 is in the OFF state (the state shown in FIG. 1), the plasma P from the plasma gun 7 is emitted into the generation chamber 10b, so that plasma P is generated in the generation chamber 10b. The plasma P is composed of neutral particles, positive ions, negative ions (if a negative gas such as oxygen gas is present), and electrons. Therefore, electrons are generated within the generation chamber 10b. When the short-circuit switch SW1 is in the ON state (the state shown in FIG. 2), the plasma P from the plasma gun 7 is not emitted into the generation chamber 10b, so the electron temperature of the plasma P in the generation chamber 10b decreases rapidly. . Therefore, electrons tend to attach to particles of the gas supplied into the generation chamber 10b. Thereby, negative ions are efficiently generated within the generation chamber 10b.

The control unit 50 controls voltage application by the voltage application unit 90. The control unit 50 applies a voltage by the voltage application unit 90 at a predetermined timing (for example, the timing when the plasma P is stopped). Note that the timing at which the voltage application unit 90 starts applying the voltage is set in advance by the control unit 50. By applying a positive bias voltage to the compound semiconductor 11 by the voltage application section 90, negative ions in the vacuum chamber 10 are guided to the compound semiconductor 11. This irradiates the compound semiconductor with negative ions.

Here, the relationship between the compound semiconductor 11 and negative ions will be explained. The compound semiconductor 11 is formed of positive ions (cations) and negative ions (anions). Such a compound semiconductor 11 is irradiated with negative ions containing the same element as the anions forming the compound semiconductor 11. Further, the gas supplied by the gas supply section 40 contains the same element as the anion forming the compound semiconductor 11. Note that the gas also includes rare gases such as Ar.

For example, when the compound semiconductor 11 is made of ZnO, Ga ₂ O ₃ , etc., it is irradiated with negative ions such as O ^- . The gas in the gas supply unit 40 includes O ₂ and the like. When the compound semiconductor 11 is formed of AlN, GaN, etc., it is irradiated with negative ions of nitride such as NH ^{2 -} . Note that the implanted H is removed by annealing. The gas in the gas supply unit 40 includes NH ₂ , NH ₄ , and the like. In addition, when the compound semiconductor 11 is formed of SiC or the like, negative ions such as C ^{2 -} and Si ^{2 -} are irradiated. The gas in the gas supply section 40 contains C ₂ H ₆ , SiH ₄ , and the like. Note that when the compound semiconductor 11 is SiC, since Si can also be a negative ion, the cation side can also be irradiated as a negative ion.

Note that atoms and molecules with positive electron affinity tend to become negative ions. Therefore, when the compound semiconductor 11 contains negative ions of such atoms and molecules, negative ions containing the same atoms and molecules may be irradiated. For example, H, He, C, O, F, Si, S, Cl, Br, I, H ₂ , O ₂ , Cl ₂ , Br ₂ , I ₂ , CH, OH, CN, Examples include HCl, HBr, NH ₂ , N ₂ O, NO ₂ , CCl ₄ , SF ₆ and the like.

Next, with reference to FIG. 3, a method of controlling the negative ion irradiation device 1 will be described. FIG. 3 is a flowchart showing a method of controlling the negative ion irradiation device 1 according to this embodiment. Here, an example will be explained in which the compound semiconductor 11 is made of ZnO and is irradiated with O ^{2 -} negative ions.

As shown in FIG. 3, the control method of the negative ion irradiation device 1 includes a gas supply step S10, a plasma generation step S20 (part of the negative ion irradiation step), and a voltage application step S30 (part of the negative ion irradiation step). ) and. Each step is executed by the control unit 50.

First, the gas supply control section 51 of the control section 50 controls the gas supply section 40 to supply gas into the vacuum chamber 10 (gas supply step S10). As a result, O ₂ gas is present in the generation chamber 10b of the vacuum chamber 10. After that, a plasma generation step S20 is performed.

The plasma control unit 52 of the control unit 50 controls the plasma generation unit 14 to generate plasma P and electrons in the vacuum chamber 10, and stops the generation of the plasma P to generate negative ions by the electrons and gas. (plasma control step S20). When plasma P and electrons are generated within the generation chamber 10b of the vacuum chamber 10, the plasma P causes the reaction "O ₂ +e ⁻ →2O+e ⁻ " to proceed. Thereafter, when the generation of plasma P is stopped, the electron temperature rapidly decreases in the generation chamber 10b, so that the reaction "O+e ⁻ →O ⁻ " progresses. At a predetermined timing after the plasma generation step S20 is performed, the voltage application step S30 is performed. Note that, strictly speaking, negative ions are generated even during plasma generation, and during negative ion irradiation, the negative ions generated during plasma generation are also irradiated.

The voltage control unit 53 of the control unit 50 controls the voltage application unit 90 to apply a bias voltage to the compound semiconductor 11 (voltage control step S30). As a result, the O ^{2 −} negative ions 81 in the generation chamber 10b head toward the compound semiconductor 11 and are irradiated onto the compound semiconductor 11 (see FIGS. 2 and 4).

Next, the functions and effects of the negative ion irradiation device 1 and its control method according to this embodiment will be explained.

In the negative ion irradiation device 1 according to this embodiment, the control section 50 controls the gas supply section 40 to supply gas into the vacuum chamber 10 . The gas supply unit 40 supplies a gas containing the same element as the ions forming the compound semiconductor 11 . Therefore, the same element as the ions forming the compound semiconductor 11 is present in the vacuum chamber 10. The control unit 50 controls the plasma generation unit 14 to generate plasma P and electrons in the vacuum chamber 10, and stops generation of the plasma P to generate negative ions from the electrons and gas. , irradiates the compound semiconductor 11 with the negative ions.

For example, as shown in FIG. 4A, negative ions 81 of the same element as the ions forming the compound semiconductor 11 are irradiated onto the compound semiconductor 11. Negative ions 81 enter into the compound semiconductor 11 from the surface 11a. As a result, the negative ions 81 enter the crystal defects 85 derived from anions in the compound semiconductor 11, so that the crystal defects 85 can be filled as shown in FIG. 4(b).

Here, the merits of irradiating the compound semiconductor 11 with negative ions will be explained with reference to FIGS. 5 and 6. 5 and 6 show the ionic bonding structure of the cations 86 and anions 87 forming the compound semiconductor 11. FIG. 5 is a diagram schematically showing a situation when positive ions 83 are implanted into a compound semiconductor as a comparative example. As shown in FIG. 5, when positive ions 83 are implanted into the compound semiconductor 11, the positive ions 83 must pass through the influence of the Coulomb force between the positive ions 86 and the negative ions 87. , there is a problem that it is difficult to enter the compound semiconductor 11 smoothly. Further, when electrons 82 are emitted as secondary electrons due to the injection of positive ions 83, a problem arises in that the substrate is charged up.

On the other hand, when negative ions 81 (see FIG. 6(a)) heading towards the compound semiconductor 11 reach the compound semiconductor 11, electrons 82 are likely to be taken out by collision, as shown in FIG. 6(b). Therefore, the negative ions 81 proceed through the ionic bond as particles 81a in a neutral state from which electrons 82 have been removed. Particles 81a in a neutral state can smoothly enter the inside of compound semiconductor 11 without being affected by the Coulomb force between cations 86 and anions 87. Therefore, the energy of the negative ions 81 may be as low as, for example, 70 eV or less. Further, when the negative ions 81 are implanted, charge-up of the substrate does not occur. Note that the negative ions 81 are implanted into the compound semiconductor 11 that is heated by the heating section 30 (see FIG. 1). Therefore, the desired element enters deep into the compound semiconductor 11 by concentration diffusion, and the excess element is removed by heat treatment, so that the particles 81a can fill only the crystal defects.

Further, for example, when negative ions are irradiated using a negative ion source as a comparative example, the area that can be irradiated with negative ions is small. On the other hand, as in this embodiment, the negative ion irradiation device 1 including the plasma generation section 14 can irradiate the compound semiconductor 11 with negative ions over a large area. Further, for example, when only negative ions of a single energy are irradiated as a comparative example, the negative ions enter only a predetermined depth position of the compound semiconductor 11, so it is not possible to fill crystal defects over a wide range in the depth direction. Can not. On the other hand, the negative ion irradiation device 1 according to this embodiment can generate negative ions with a wide range of energies, and therefore can fill crystal defects over a wide range in the depth direction.

As described above, the negative ion irradiation device 1 according to the present embodiment can fill crystal defects in the compound semiconductor 11, thereby improving the quality of the compound semiconductor 11. Furthermore, even if the grade of the compound semiconductor 11 is not sufficient before negative ion irradiation, the quality can be improved by negative ion irradiation, reducing the need to select the grade of the single crystal substrate in advance. Can be done. With the above, manufacturing efficiency and quality of compound semiconductors can be improved.

The method for controlling the negative ion irradiation apparatus 1 according to the present embodiment includes a gas supply step S10 for supplying gas into the vacuum chamber 10 by controlling the gas supply section 40, and a gas supply step S10 for supplying gas into the vacuum chamber 10 by controlling the plasma generation section 14 to A negative ion irradiation step (plasma control) in which plasma P and electrons are generated in the compound semiconductor 10, and negative ions are generated from the electrons and gas by stopping the generation of the plasma P, and the compound semiconductor 11 is irradiated with the negative ions. The method includes step S20 and voltage application step S30).

Depending on the method of controlling the negative ion irradiation device 1 according to this embodiment, the same functions and effects as those of the negative ion irradiation device 1 described above can be obtained.

Although one embodiment of the present embodiment has been described above, the present invention is not limited to the above embodiment, and may be modified or applied to other things without changing the gist of each claim. It may be something.

Further, in the above embodiment, a negative ion irradiation device that also functions as an ion plating type film forming device has been described, but the negative ion irradiation device does not need to have the function of a film forming device. Therefore, the plasma P may be guided, for example, to an electrode on a wall facing the plasma gun.

For example, in the above embodiment, the plasma gun 7 is a pressure gradient type plasma gun, but the plasma gun 7 is not limited to a pressure gradient type as long as it can generate plasma in the vacuum chamber 10.

Further, in the above embodiment, only one set of the plasma gun 7 and the point (Haas mechanism 2) for guiding the plasma P is provided in the vacuum chamber 10, but a plurality of sets may be provided. Alternatively, plasma P may be supplied to one location from a plurality of plasma guns 7.

DESCRIPTION OF SYMBOLS 1... Negative ion irradiation device (negative ion irradiation device), 3... Transport mechanism (arrangement part), 7... Plasma gun, 10... Vacuum chamber, 11... Compound semiconductor, 14... Plasma generation part, 40... Gas supply part, 50 ...Control unit, P...Plasma.

Claims (2)

A negative ion irradiation device that irradiates a single crystal substrate made of a compound semiconductor with negative ions,
a chamber in which the negative ions are generated;
a gas supply unit that supplies a gas containing the same element as the ions forming the single crystal substrate made of the compound semiconductor;
a plasma generation section that generates plasma and electrons in the chamber;
an arrangement section in which the single crystal substrate made of the compound semiconductor is arranged;
A control unit that controls the negative ion irradiation device,
The single crystal substrate made of the compound semiconductor is manufactured in advance outside the chamber,
The placement section is configured to be able to place a single crystal substrate made of the compound semiconductor manufactured in advance externally,
The control unit includes:
controlling the gas supply unit to supply the gas into the chamber;
Controlling the plasma generation unit to generate the plasma and the electrons in the chamber, and stopping generation of the plasma to generate the negative ions from the electrons and the gas, and generate the negative ions. A negative ion irradiation device that irradiates a single crystal substrate made of the compound semiconductor arranged in the chamber. A method for controlling a negative ion irradiation device that irradiates a single crystal substrate made of a compound semiconductor with negative ions, the method comprising:
The negative ion irradiation device includes:
a chamber in which the negative ions are generated;
a gas supply unit that supplies a gas containing the same element as the ions forming the single crystal substrate made of the compound semiconductor;
a plasma generation section that generates plasma and electrons in the chamber;
an arrangement section in which the single crystal substrate made of the compound semiconductor is arranged;
A control unit that controls the negative ion irradiation device,
The single crystal substrate made of the compound semiconductor is manufactured in advance outside the chamber,
The placement section is configured to be able to place a single crystal substrate made of the compound semiconductor manufactured in advance externally,
a gas supply step of controlling the gas supply unit by the control unit to supply the gas into the chamber;
The control unit controls the plasma generation unit to generate the plasma and the electrons in the chamber, and stops generation of the plasma to generate the negative ions from the electrons and the gas. A method for controlling a negative ion irradiation device, comprising: a negative ion irradiation step of irradiating the single crystal substrate made of the compound semiconductor disposed in the chamber with the negative ions.

Images