WO2010082345A1 - Procédé de formation de points de silicium et appareil de formation de points de silicium - Google Patents

Procédé de formation de points de silicium et appareil de formation de points de silicium Download PDF

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WO2010082345A1
WO2010082345A1 PCT/JP2009/050630 JP2009050630W WO2010082345A1 WO 2010082345 A1 WO2010082345 A1 WO 2010082345A1 JP 2009050630 W JP2009050630 W JP 2009050630W WO 2010082345 A1 WO2010082345 A1 WO 2010082345A1
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plasma
silicon
chamber
silicon dot
plasma generation
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English (en)
Japanese (ja)
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司 林
敦志 東名
建治 加藤
英治 高橋
隆司 三上
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日新電機株式会社
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Priority to PCT/JP2009/050630 priority Critical patent/WO2010082345A1/fr
Priority to JP2010546524A priority patent/JPWO2010082345A1/ja
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32082—Radio frequency generated discharge
    • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/04—Coating on selected surface areas, e.g. using masks
    • C23C16/047—Coating on selected surface areas, e.g. using masks using irradiation by energy or particles
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/24—Deposition of silicon only
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32082—Radio frequency generated discharge
    • H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled to the plasma
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192—Microwave generated discharge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/3266—Magnetic control means

Definitions

  • the present invention is a microscopic silicon crystalline particle (hereinafter also referred to as “silicon dot”) which is also referred to as a silicon nanoparticle used as an electronic device material or a light emitting material for a single electronic device or the like.
  • the present invention relates to a forming method and a forming apparatus.
  • silicon nanoparticles As a method of forming silicon nanoparticles (silicon dots), a physical method is known in which silicon is heated and evaporated using an excimer laser or the like in an inert gas, and a gas evaporation method is also known. (See Kanagawa Prefectural Institute of Advanced Industrial Science and Technology, Research Report No. 9/2003, pages 77-78). The latter is a technique in which silicon is heated and evaporated by high frequency induction heating or arc discharge instead of laser.
  • a CVD method is also known in which a material gas is introduced into a CVD chamber to form silicon nanoparticles on a heated substrate (see Japanese Patent Application Laid-Open No. 2004-179658).
  • silicon nanoparticles are grown from the nucleus through a step of forming a nucleus for growing silicon nanoparticles on the substrate.
  • JP 2004-179658 A Kanagawa AIST Research Report No.9 / 2003 pp. 77-78
  • the method of heating and evaporating silicon by laser irradiation is difficult to irradiate silicon with laser by uniformly controlling the energy density. It is difficult to align the distribution. Even in the gas evaporation method, non-uniform heating of silicon occurs, and it is difficult to make the particle size and density distribution of silicon dots uniform.
  • the substrate when the nucleus is formed on the substrate, the substrate must be heated to about 550 ° C. or more, a substrate having a low heat-resistant temperature cannot be adopted, and the substrate material can be selected. That is the limit.
  • the present invention provides a silicon dot forming method that can form silicon dots having a uniform particle diameter on a silicon dot formation target substrate with a uniform density distribution and has a wide selectable range of substrate materials in terms of heat resistance. Let it be the first problem.
  • the present invention also provides a silicon dot forming apparatus capable of forming silicon dots having a uniform particle diameter on a silicon dot formation target substrate with a uniform density distribution and having a wide selectable range of base material in terms of heat resistance. Let it be the 2nd subject.
  • the present inventor conducted research to solve the above-mentioned problems and found the following.
  • a gas containing silicon for example, a gas such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), silicon tetrafluoride (SiF 4 )
  • SiH 4 monosilane
  • Si 2 H 6 disilane
  • SiCl 4 silicon tetrachloride
  • SiF 4 silicon tetrafluoride
  • the positive ions are SiH 3 + , SiH 2 + , Si 2 H X + (x is 1 to 7). ), Si n H y + (n is an integer of 3 or more, y is an integer of y ⁇ 2n + 2), etc., and these plural types of positive ions are generated.
  • silicon dots can be formed over a wide range of substrates in a shorter time than when using mass-separated positive ions, and the negative ions containing silicon are substantially the same type.
  • the silicon dot density distribution can be made uniform.
  • a gas containing silicon for example, a gas such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), silicon tetrafluoride (SiF 4 )
  • SiH 4 monosilane
  • Si 2 H 6 disilane
  • SiCl 4 silicon tetrachloride
  • SiF 4 silicon tetrafluoride
  • mass separation must be performed to selectively direct only positive ions of a predetermined mass to the silicon dot formation target, but this requires an expensive and bulky mass separator, Further, since the positive ions selected by the mass separation process have a small beam diameter, a scanning means is required to form silicon dots over a wide area of the substrate, and it takes time to form silicon dots over a wide area.
  • a negative ion of substantially the same type is extracted by applying a voltage for extracting the negative ion to the ion extraction electrode device and irradiated to the silicon dot formation target substrate, a mass separation device or a scanning mechanism
  • silicon dots can be formed over a wide area of the substrate in a shorter time than when mass-separated positive ions are used, and the negative ions containing silicon are substantially the same type.
  • the diameter can be made uniform and the silicon dot density distribution can be made uniform.
  • a gas containing silicon for example, a gas such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), silicon tetrafluoride (SiF 4 )
  • SiH 4 monosilane
  • Si 2 H 6 disilane
  • SiCl 4 silicon tetrachloride
  • SiF 4 silicon tetrafluoride
  • the plasma is a plasma having a low plasma potential such as inductively coupled plasma.
  • the types of plasma include low-potential plasma such as inductively coupled plasma and electrostatically coupled plasma (capacitively coupled plasma).
  • electrostatic coupling type plasma since the plasma density (number of ions per 1 cm 3 ) is relatively low and the plasma potential is relatively high, crystalline silicon dots are formed on the silicon dot formation target substrate. Is difficult. In order to form crystalline silicon dots by the plasma CVD method, it is necessary to better decompose the gas containing silicon and lower the plasma potential.
  • the plasma density is low, that is, if the gas containing silicon is poorly decomposed, a large amount of hydrogen and other impurities are likely to be mixed into the silicon nanoparticles (silicon dots), and the dots are in an amorphous state or a microcrystalline state. It is difficult to obtain quality silicon dots.
  • the plasma potential is high, the formed silicon crystal is easily destroyed (in other words, susceptible to plasma damage), and the dots are in an amorphous state or a microcrystalline state. In this case, it is difficult to obtain crystalline silicon dots.
  • the substrate is a low-cost substrate such as a low-melting glass substrate.
  • the substrate is a low-cost substrate such as a low-melting glass substrate.
  • plasma with a low plasma potential such as inductively coupled plasma has a feature that a high plasma density and a low plasma potential are easily obtained as compared with electrostatic coupled plasma. Therefore, in the formation of silicon dots by low plasma potential plasma such as inductively coupled plasma, it is easy to form relatively crystalline silicon dots.
  • an ion beam is applied to the surface of the substrate. It may be irradiated. By irradiating the ion beam during the formation of the silicon dots, the movement or migration of the silicon atoms is promoted, and the crystallinity of the silicon dots becomes higher.
  • the present invention provides the following first silicon dot forming method and first silicon dot forming apparatus. Further, based on the second knowledge, a second silicon dot forming method and a second silicon dot forming apparatus, which will be described later, are provided. Furthermore, a third silicon dot forming method to be described later is provided based on the third knowledge.
  • First Silicon Dot Forming Method and First Silicon Dot Forming Apparatus (1-1) First Silicon Dot Forming Method A substrate placement electrode that includes a plasma generation device and places a silicon dot formation target substrate therein Preparing an installed plasma generation chamber; Installing a silicon dot formation target substrate on the substrate installation electrode; Evacuating from the plasma generation chamber, introducing a gas containing silicon into the plasma generation chamber while maintaining the plasma generation chamber at a silicon dot forming pressure, and generating plasma from the gas by the plasma generation device; By applying a first positive pulse voltage to the substrate installation electrode, the silicon dot formation target substrate installed on the electrode is irradiated with negative ions containing silicon in the plasma with a first ion energy.
  • a silicon dot forming method comprising growing silicon dots on the silicon dot formation target substrate based on the nucleus.
  • (1-2) First silicon dot forming device A plasma generating chamber provided with a plasma generating device and provided with a substrate installation electrode for setting a silicon dot formation target substrate therein, A gas introduction device for introducing a gas containing silicon into the plasma generation chamber; An exhaust device for exhausting from the plasma generation chamber; A positive bias power supply device for applying a positive pulse voltage to the substrate installation electrode,
  • the plasma generation device is a device that generates plasma containing negative ions including silicon from the gas introduced into the plasma generation chamber by the gas introduction device,
  • the positive bias power supply device irradiates the substrate installation electrode with negative ions containing silicon in the plasma to the silicon dot formation target substrate installed on the electrode with a first ion energy, thereby generating silicon dots.
  • a silicon dot forming device which is a power supply device for applying a second positive pulse voltage for growing silicon dots.
  • Second Silicon Dot Forming Method and Silicon Dot Forming Apparatus (2-1) Second Silicon Dot Forming Method
  • a plasma generation chamber provided with a plasma generation device, and silicon dot formation connected to the plasma generation chamber
  • a gas containing silicon is contained in the plasma generation chamber while exhausting the plasma generation chamber and the silicon dot formation chamber to maintain the plasma generation chamber at the plasma generation pressure and maintaining the silicon dot formation chamber at the silicon dot formation pressure.
  • a first negative ion extraction voltage is applied to the negative ion extraction electrode device to extract negative ions including silicon in the plasma to the silicon dot formation chamber. Irradiating with an ion energy of 1 to form nuclei for silicon dot growth on the silicon dot formation target substrate; Following the nucleation, a second negative ion extraction voltage is applied to the negative ion extraction electrode device to extract negative ions including silicon in the plasma to the silicon dot formation chamber, and a second substrate is formed on the silicon dot formation target substrate.
  • a silicon dot forming method comprising: irradiating with ion energy to grow silicon dots on the silicon dot formation target substrate based on the nuclei.
  • (2-2) Second silicon dot forming apparatus a plasma generating chamber provided with a plasma generating apparatus; A silicon dot forming chamber that is connected to the plasma generation chamber and in which a substrate setting portion for setting a silicon dot forming target substrate is disposed; A negative ion extraction electrode device provided in an opening facing the substrate installation portion of the plasma generation chamber; A gas introduction device for introducing a gas containing silicon into the plasma generation chamber; An exhaust device for exhausting air from the plasma generation chamber and the silicon dot formation chamber; A negative ion extraction power supply device for applying a voltage for extracting negative ions including silicon to the negative ion extraction electrode device;
  • the plasma generation device is a device that generates plasma containing negative ions including silicon from the gas introduced into the plasma generation chamber by the gas introduction device,
  • the negative ion extraction power supply device causes the negative ion extraction electrode device to supply negative ions including silicon in the plasma to a silicon dot formation target substrate installed in a substrate installation portion of the silicon dot formation chamber with a first ion energy
  • a silicon dot forming apparatus which is a power supply device that applies a second negative ion extraction voltage for growing silicon dots based on the nuclei by irradiation with the nuclei.
  • a plasma generating chamber provided with a plasma generating chamber having a low plasma potential plasma generation apparatus and a substrate installation part for installing a silicon dot formation target substrate therein, and an ion beam are supplied to the substrate installation part.
  • Preparing an ion beam irradiation apparatus for irradiating a silicon dot formation target substrate to be installed Installing a silicon dot formation target substrate in the substrate installation portion;
  • a gas containing silicon is introduced into the plasma generation chamber while evacuating the plasma generation chamber while maintaining the plasma generation chamber at the silicon dot formation pressure, and the low plasma potential plasma is generated from the gas by the low plasma potential plasma generation device.
  • the ion beam irradiation is performed by irradiating an ion beam with a first ion energy for forming a nucleus that becomes a silicon dot on the silicon dot formation target substrate, and then applying a silicon dot based on the nucleus.
  • FIG. 5 is a diagram showing a schematic configuration of another example of the first silicon dot forming apparatus according to the present invention. It is a figure which shows schematic structure of the further another example of the 1st silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of the further another example of the 1st silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of the further another example of the 1st silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of the further another example of the 1st silicon dot formation apparatus which concerns on this invention.
  • FIG. 12 It is a figure which shows schematic structure of one example of the 2nd silicon dot formation apparatus which concerns on this invention. It is a figure which shows the timing of plasma lighting-on / off and negative ion extraction voltage application (negative ion beam extraction) to a negative ion extraction electrode apparatus. It is a figure which shows schematic structure of the other example of the 2nd silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of the further another example of the 2nd silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of the further another example of the 2nd silicon dot formation apparatus which concerns on this invention. It is a figure which shows schematic structure of one example of a 3rd silicon dot formation apparatus. It is the figure which looked at the antenna employ
  • First type silicon dot forming method and first type silicon dot forming apparatus, second type silicon dot forming method, second type silicon dot forming apparatus, and third type silicon described below as embodiments of the present invention The dot formation method can be mentioned.
  • First type silicon dot forming method and apparatus (1) First type silicon dot forming method The first type silicon dot forming method basically includes: Preparing a plasma generation chamber provided with a substrate installation electrode provided with a plasma generation device and having a silicon dot formation target substrate installed therein; Installing a silicon dot formation target substrate on the substrate installation electrode; Evacuating from the plasma generation chamber, introducing a gas containing silicon into the plasma generation chamber while maintaining the plasma generation chamber at a silicon dot forming pressure, and generating plasma from the gas by the plasma generation device; By applying a first positive pulse voltage to the substrate installation electrode, the silicon dot formation target substrate installed on the electrode is irradiated with negative ions containing silicon in the plasma with a first ion energy.
  • a silicon dot forming method including growing silicon dots on the silicon dot formation target substrate based on the nucleus.
  • the first type silicon dot forming device is basically A plasma generation chamber provided with a substrate generation electrode provided with a plasma generation device and having a silicon dot formation target substrate installed therein; A gas introduction device for introducing a gas containing silicon into the plasma generation chamber; An exhaust device for exhausting from the plasma generation chamber; A positive bias power supply device for applying a positive pulse voltage to the substrate installation electrode,
  • the plasma generation device is a device that generates plasma containing negative ions including silicon from the gas introduced into the plasma generation chamber by the gas introduction device, The positive bias power supply device irradiates the substrate installation electrode with negative ions containing silicon in the plasma to the silicon dot formation target substrate installed on the electrode with a first ion energy, thereby generating silicon dots.
  • a silicon dot forming device which is a power supply device for applying a second positive pulse voltage for growing silicon dots.
  • silicon dots having a uniform particle diameter can be formed on the silicon dot formation target substrate with a uniform density distribution. Moreover, silicon dots can be formed even when the substrate temperature is relatively low, and a substrate material can be selected from a wide range in terms of heat resistance.
  • silicon dots can be formed over a wide area of the substrate in a shorter time than when using mass-separated positive ions without requiring expensive devices such as a mass separation device or an ion beam scanning mechanism.
  • the first ion energy is obtained when the plasma potential of the plasma is P [V].
  • P [eV] or more, and the second ion energy is 2 keV or less, more preferably 500 eV or less (therefore, the first and second positive pulse voltages are pulse voltages that can obtain such ion energy).
  • P itself in P [V] and P [eV] is a numerical value.
  • the silicon dots to be grown based on the “nuclei” are greatly affected by the sputtering action or collision destruction action by the ions, making it difficult to grow the silicon dots.
  • the second ion energy is 2 keV or less, more preferably 500 eV or less, there is an effect of promoting movement or migration of silicon atoms by ion irradiation, and high-quality silicon dots with high crystallinity are grown.
  • the second ion energy is too low, silicon dots may be difficult to grow. For example, in view of the plasma potential, an example of 50 eV or more can be given.
  • the plasma contains more negative ions containing silicon. In other words, it is better that the negative ion concentration in the plasma is higher.
  • Method 1 for increasing negative ion concentration This is a method for increasing negative ion density by performing plasma lighting in a pulsed manner and applying a positive voltage pulsed to the base electrode immediately after the plasma is extinguished. Furthermore, plasma is generated from the plasma source gas by turning on the plasma generating device. Next, the plasma generator is turned off. As a result, the temperature of the electrons in the plasma decreases rapidly. During this period, the density of electrons and positive and negative ions hardly changes. Therefore, low-energy electrons are dominant in the plasma. The probability that negative ions are generated rapidly due to the dissociative adhesion between the slow electrons and the molecules increases rapidly.
  • the negative ion density rapidly increases immediately after the plasma generator is turned off. As the time further elapses, the electrons are light, so that they diffuse rapidly and disappear and the density decreases. On the other hand, since positive and negative ions have a large mass, they hardly disappear. For this reason, the electron density becomes extremely low, and a peculiar plasma (having almost no electrons) in which the plasma is maintained by positive and negative ions is formed.
  • Method 1 can be used in combination with Method 2 and Method 3 described later.
  • the plasma generation chamber is divided into two, and a raw material gas is guided to one of the first plasma chambers to excite it to generate plasma.
  • a base electrode is provided in the other second plasma chamber.
  • An energy filter using a magnetic field is provided between the two plasma chambers.
  • the first plasma chamber vigorous plasma generation is performed and the energy of electrons is high. High-energy electrons are difficult to bond with neutral radicals and atoms.
  • the energy filter suppresses the passage of high energy electrons.
  • the second plasma chamber has many low energy electrons. Low energy electrons have a large cross-sectional area of collisional bonds with neutral molecules and atoms.
  • Low energy electrons are linked to neutral radicals and negatively ionized to SiH 3 ⁇ , SiH 2 ⁇ , and the like. When the number of low energy electrons decreases in such a manner, low energy electrons enter the second plasma chamber from the first plasma chamber.
  • the energy filter is selective to electronic energy. Neutral atoms and molecules are allowed to pass freely. This is done by creating a magnetic field of about several tens of Gauss. Such a magnetic field can be generated, for example, by opposing permanent magnets. Alternatively, a magnetic field can be generated by passing a current through a plurality of parallel conductor bars.
  • the third method is a method of increasing the negative ion density by utilizing the low work function of cesium or the like.
  • This method is already widely used as a negative ion source.
  • cesium (Cs) When cesium (Cs) is adsorbed on the metal surface, it has the effect of lowering the work function of the metal surface. Since the work function is lowered, electrons are more easily emitted. Therefore, when the metal is negatively biased, the metal functions as an electron emitter. Electrons are given to SiH x radicals, molecules, positive ions, etc., which are negatively ionized. Cs can be stored in a solid state in the evaporation source and vaporized by heating to be led to the metal surface. In addition to Cs, rubidium (Rb), potassium (K), barium (Ba), and the like can also be used.
  • the method 1 is used to periodically turn on and off the plasma generation device, and the application of a positive pulse voltage to the substrate installation electrode turns off the plasma generation device. You may make it carry out during the period until this plasma production
  • the plasma generating apparatus is periodically turned on and off so that the method 1 can be used, and a positive pulse voltage is applied to the substrate installation electrode by the positive bias power supply apparatus.
  • a control unit that controls the plasma generation device and the positive bias power supply device so as to be performed during a period from when the plasma generation device is turned off to when the plasma generation device is turned on again after a lapse of a predetermined period.
  • the method 2 is used to form an electron trapping magnetic field in an intermediate portion of the plasma generation chamber, and one side of the plasma generation chamber from the electron trapping magnetic field formation region.
  • a first plasma chamber provided with the plasma generating device and the other side is a second plasma chamber having the base electrode, and plasma is generated from the gas containing silicon in the first plasma chamber, and the electrons
  • the movement of some of the electrons in the plasma generated in the first plasma chamber by the trapped magnetic field to the second plasma chamber is suppressed, and the movement to the second plasma chamber that arrives in the second plasma chamber is suppressed.
  • the concentration of negative ions including silicon in the second plasma chamber may be increased by the action of electrons having lower energy than the generated electrons. .
  • the first type silicon dot forming apparatus includes a magnetic field forming device for forming an electron trapping magnetic field in an intermediate portion of the plasma generation chamber so that the method 2 can be used, and the electron trapping magnetic field in the plasma generation chamber
  • a magnetic field forming device for forming an electron trapping magnetic field in an intermediate portion of the plasma generation chamber so that the method 2 can be used, and the electron trapping magnetic field in the plasma generation chamber
  • One side from the formation region is a first plasma chamber provided with the plasma generation device, and the other side is a second plasma chamber having the base electrode, and the silicon is generated in the first plasma chamber by the plasma generation device.
  • Plasma is generated from the gas containing, and the movement of a part of the electrons in the plasma generated in the first plasma chamber by the electron trapping magnetic field formed by the magnetic field forming device to the second plasma chamber is suppressed, Silicon in the second plasma chamber is caused by the action of electrons arriving in the second plasma chamber and having lower energy than the electrons whose movement to the second plasma chamber is suppressed.
  • a silicon dot forming apparatus capable of increasing the concentration of negative ions, including.
  • the action of low energy electrons arriving in the second plasma chamber means that the low energy electrons collide with neutral atoms and molecules in the second plasma chamber. This is an action of increasing negative ions including.
  • the method 3 is used to previously provide a conductive target in which at least one substance selected from cesium, rubidium, potassium, and barium is deposited in the plasma generation chamber. Applying a negative voltage to the conductive target in plasma generation from the silicon-containing gas by the plasma generation apparatus in the plasma generation chamber, and bringing positive ions in the plasma into contact with the target.
  • the concentration of negative ions containing silicon may be increased.
  • the conductive target in which at least one material selected from the cesium, rubidium, potassium, and barium is deposited is provided, for example, by providing a conductive target before the material deposition in the plasma generation chamber. It can be obtained by introducing the vapor of at least one substance selected from cesium, rubidium, potassium and barium to the target and depositing the substance.
  • the first type silicon dot forming apparatus is previously provided with a conductive target in which at least one substance selected from cesium, rubidium, potassium, and barium is deposited in the plasma generation chamber.
  • a silicon dot forming device provided with a negative bias power supply device for applying a negative voltage to the conductive target in the plasma generation from the gas containing silicon by the plasma generation device in the plasma generation chamber.
  • the first type silicon dot forming apparatus uses the method 3 to A conductive target installed in the plasma generation chamber; A material deposition apparatus for generating a vapor of at least one material selected from cesium, rubidium, potassium and barium, leading to the conductive target, and depositing the material on the target; A negative bias power supply device for applying a negative voltage to the conductive target on which the material is deposited by the material deposition device in plasma generation from the gas containing silicon by the plasma generation device in the plasma generation chamber; But you can.
  • Second type silicon dot forming method and silicon dot forming apparatus (2-1) Second type silicon dot forming method
  • the second type silicon dot forming method is basically A plasma generation chamber provided with a plasma generation device, a silicon dot formation chamber arranged in a continuous manner with the plasma generation chamber, and a substrate installation portion for installing a silicon dot formation target substrate, and the substrate installation portion of the plasma generation chamber Preparing a negative ion extraction electrode device provided in an opening facing the surface; Installing a silicon dot formation target substrate in the substrate installation portion; A gas containing silicon is contained in the plasma generation chamber while exhausting the plasma generation chamber and the silicon dot formation chamber to maintain the plasma generation chamber at the plasma generation pressure and maintaining the silicon dot formation chamber at the silicon dot formation pressure.
  • a first negative ion extraction voltage is applied to the negative ion extraction electrode device to extract negative ions including silicon in the plasma to the silicon dot formation chamber. Irradiating with an ion energy of 1 to form nuclei for silicon dot growth on the silicon dot formation target substrate; Following the nucleation, a second negative ion extraction voltage is applied to the negative ion extraction electrode device to extract negative ions including silicon in the plasma to the silicon dot formation chamber, and a second substrate is formed on the silicon dot formation target substrate.
  • a silicon dot forming method comprising irradiating with ion energy and growing silicon dots on the silicon dot formation target substrate based on the nuclei.
  • the second type silicon dot forming device is basically composed of: A plasma generation chamber equipped with a plasma generation device; A silicon dot forming chamber that is connected to the plasma generation chamber and in which a substrate setting portion for setting a silicon dot forming target substrate is disposed; A negative ion extraction electrode device provided in an opening facing the substrate installation portion of the plasma generation chamber; A gas introduction device for introducing a gas containing silicon into the plasma generation chamber; An exhaust device for exhausting air from the plasma generation chamber and the silicon dot formation chamber; A negative ion extraction power supply device for applying a voltage for extracting negative ions including silicon to the negative ion extraction electrode device;
  • the plasma generation device is a device that generates plasma containing negative ions including silicon from the gas introduced into the plasma generation chamber by the gas introduction device,
  • the negative ion extraction power supply device causes the negative ion extraction electrode device to supply negative ions including silicon in the plasma to a silicon dot formation target substrate installed in a substrate installation portion of the silicon dot formation chamber with
  • silicon dots having a uniform particle diameter can be formed with a uniform density distribution on the silicon dot formation target substrate.
  • silicon dots can be formed even when the substrate temperature is relatively low, and a substrate material can be selected from a wide range in terms of heat resistance.
  • silicon dots can be formed over a wide range of the substrate in a shorter time than when using mass-separated positive ions without requiring expensive devices such as a mass separation device or an ion beam scanning mechanism.
  • the P [eV And the second ion energy is 2 keV or less, more preferably 500 eV or less (therefore, the first and second negative ion extraction voltages applied to the negative ion extraction electrode device can obtain such ion energy.
  • P itself of P [V] and P [eV] is a numerical value.
  • the silicon dots to be grown based on the “nuclei” are greatly affected by the sputtering action or collision destruction action by the ions, making it difficult to grow the silicon dots.
  • the second ion energy is 2 keV or less, more preferably 500 eV or less, there is an effect of promoting movement or migration of silicon atoms by ion irradiation, and high-quality silicon dots with high crystallinity are grown.
  • the second ion energy is too low, silicon dots may be difficult to grow. For example, in view of the plasma potential, an example of 50 eV or more can be given.
  • the second type silicon dot forming method and apparatus when forming silicon dots having a uniform particle size on a silicon dot formation target substrate with a uniform density distribution, more negative ions containing silicon are included in the plasma. It is better to be. In other words, it is better that the negative ion concentration in the plasma is higher.
  • the above-described methods 1, 2 and 3 can be used as a method for increasing the negative ion concentration.
  • the plasma generating device is periodically turned on and off so that the method 1 can be used, and negative ion extraction including the silicon to the negative ion extraction electrode device is performed.
  • the voltage application may be performed during a period from when the plasma generating apparatus is turned off to when the plasma generating apparatus is turned on again after a lapse of a predetermined period.
  • the second type silicon dot forming apparatus includes the silicon to the negative ion extraction electrode apparatus by the negative ion extraction power supply apparatus, in which the plasma generation apparatus is periodically turned on and off.
  • the application of the negative ion extraction voltage is performed during a period from when the plasma generation device is turned off to when the plasma generation device is turned on again after a lapse of a predetermined period.
  • a silicon dot forming apparatus including a control unit for controlling the ion extraction power supply device may be used.
  • the method 2 can be used.
  • An electron trapping magnetic field is formed in an intermediate portion of the plasma generating chamber, and one side of the plasma generating chamber from the electron trapping magnetic field forming region is a first plasma chamber provided with the plasma generating device and the other side is the A second plasma chamber provided with a negative ion extraction electrode device is used, a plasma is generated from the gas containing silicon in the first plasma chamber, and one of the electrons in the plasma generated in the first plasma chamber by the electron trapping magnetic field is generated.
  • the movement of the part to the second plasma chamber is suppressed, and the action of electrons having a lower energy than the electrons that have entered the second plasma chamber and are suppressed to move to the second plasma chamber
  • the concentration of negative ions including silicon may be increased.
  • the second type silicon dot forming apparatus includes a magnetic field forming device for forming an electron trapping magnetic field in an intermediate portion of the plasma generation chamber, and the electron in the plasma generation chamber
  • a magnetic field forming device for forming an electron trapping magnetic field in an intermediate portion of the plasma generation chamber, and the electron in the plasma generation chamber
  • One side from the trapping magnetic field forming region is a first plasma chamber provided with the plasma generation device, and the other side is a second plasma chamber having the negative ion extraction electrode device, and the first plasma is generated by the plasma generation device.
  • Plasma is generated from the gas containing silicon in the chamber, and a part of electrons in the plasma generated in the first plasma chamber by the electron trapping magnetic field formed by the magnetic field forming device is moved to the second plasma chamber.
  • the second plasma is generated by the action of electrons having energy lower than that of the electrons suppressed and moved to the second plasma chamber.
  • a silicon dot forming apparatus capable of increasing the concentration of negative ions containing silicon chamber.
  • the action of low energy electrons arriving in the second plasma chamber means that the low energy electrons collide with neutral atoms and molecules in the second plasma chamber. This is an action of increasing negative ions including atoms.
  • the conductive target in which at least one material selected from the cesium, rubidium, potassium, and barium is deposited is provided, for example, by providing a conductive target before the material deposition in the plasma generation chamber. It can be obtained by introducing the vapor of at least one substance selected from cesium, rubidium, potassium and barium to the target and depositing the substance.
  • the second type silicon dot forming apparatus is preliminarily provided with a conductive target in which at least one substance selected from cesium, rubidium, potassium and barium is deposited in the plasma generation chamber.
  • a silicon dot forming device provided with a negative bias power supply device for applying a negative voltage to the conductive target in plasma generation from the gas containing silicon by the plasma generation device in the plasma generation chamber. Good.
  • the second type silicon dot forming device A conductive target installed in the plasma generation chamber; A material deposition apparatus for generating a vapor of at least one material selected from cesium, rubidium, potassium and barium, leading to the conductive target, and depositing the material on the target; Silicon having a negative bias power supply device for applying a negative voltage to the conductive target on which the material is deposited by the material deposition device in plasma generation from the gas containing silicon by the plasma generation device in the plasma generation chamber It may be a dot forming device.
  • the third type silicon dot formation method is basically A plasma generating chamber having a plasma generating chamber having a low plasma potential, such as inductively coupled plasma, and a substrate setting portion for setting a silicon dot formation target substrate therein, and a silicon dot having an ion beam set in the substrate setting portion Preparing an ion beam irradiation apparatus for irradiating a substrate to be formed; Installing a silicon dot formation target substrate in the substrate installation portion; A gas containing silicon is introduced into the plasma generation chamber while evacuating the plasma generation chamber while maintaining the plasma generation chamber at the silicon dot formation pressure, and the low plasma potential plasma is generated from the gas by the low plasma potential plasma generation device.
  • the ion beam irradiation is performed by irradiating an ion beam with a first ion energy for forming a nucleus that becomes a silicon dot on the silicon dot formation target substrate, and then applying a silicon dot based on the nucleus.
  • This is a silicon dot forming method in which silicon dots are formed on the silicon dot formation target substrate by performing ion beam irradiation with second ion energy for growth.
  • silicon dots having a uniform particle diameter can be formed with a uniform density distribution on the silicon dot formation target substrate. Moreover, silicon dots can be formed even when the substrate temperature is relatively low, and a substrate material can be selected from a wide range in terms of heat resistance.
  • silicon dots can be formed over a wide area of the substrate in a shorter time than when using mass-separated positive ions without requiring expensive devices such as a mass separation device or an ion beam scanning mechanism.
  • a plasma having a low plasma potential such as inductively coupled plasma is generated from a gas containing silicon, a silicon dot formation target substrate is placed under the plasma, and an ion beam is applied to the surface of the substrate. Irradiation forms silicon dots.
  • the plasma generated from the gas containing silicon is a plasma having a low plasma potential such as inductively coupled plasma, and the plasma can have a higher plasma density and a lower plasma potential than the electrostatically coupled plasma as described above. Therefore, a silicon dot having high crystallinity can be obtained on a substrate having a relatively low heat resistance such as a low-melting glass substrate at a low temperature (for example, 600 ° C. or less) that can suppress thermal damage to the substrate. it can.
  • the surface of the substrate is irradiated with an ion beam from an ion beam irradiation device, so that migration or migration of silicon atoms is performed. Is promoted, and the crystallinity of the silicon dots becomes higher. It is not necessary to perform a separate heat treatment to increase crystallinity after the formation of silicon dots.
  • high-quality crystalline silicon dots can be obtained with high productivity.
  • the silicon dots thus obtained are of high quality with high crystallinity.
  • the ion species is selected, the ion acceleration energy is adjusted, or a combination thereof, in addition to controlling the crystallinity of the silicon dots, the crystal grains Diameter control, crystal orientation control, internal stress control, film adhesion force control, and the like can be performed.
  • an antenna for applying an inductively coupled high-frequency electric field can be installed in the plasma generation chamber, so that it is possible to easily cope with an increase in the area of the substrate.
  • the plasma density of inductively coupled plasma or the like is 1 ⁇ 10 11 ions / cm 3 or more. More preferably, it is 2 ⁇ 10 11 ions / cm 3 or more.
  • the plasma density is less than 1 ⁇ 10 11 ions / cm 3 , that is, if the gas containing silicon is poorly decomposed, a large amount of impurities such as hydrogen are likely to be mixed into the silicon dots, thereby inhibiting the formation of silicon atom networks.
  • the silicon dots may be in an amorphous or microcrystalline state, making it difficult to obtain crystalline silicon dots.
  • the upper limit value of the plasma density is not limited to this, but can be about 1 ⁇ 10 13 ions / cm 3 , for example.
  • the gas introduction device, the gas pressure adjusting device in the plasma generation chamber, and the plasma generation device (particularly the power source for plasma excitation) for converting the raw material gas into plasma are controlled together, in other words, the raw material gas.
  • the plasma density is 1 ⁇ 10 11 (ion number / cm 3 ) or more, more preferably, by means of controlling the supply amount of plasma, the pressure in the plasma generation chamber, and the power for converting the gas into plasma (high frequency power supplied to the high frequency antenna). Examples include 2 ⁇ 10 11 (ion / cm 3 ) or more, or about 1 ⁇ 10 11 (ion / cm 3 ) to 1 ⁇ 10 13 (ion / cm 3 ).
  • the potential of plasma such as inductively coupled plasma is 50 V or less in order to stably obtain crystalline silicon dots. If the plasma potential is greater than 50 V, the silicon dots are susceptible to ion damage (plasma damage) from the plasma, and the silicon dots become amorphous or microcrystalline, making it difficult to obtain crystalline silicon dots. .
  • the plasma potential is more preferably 30 V or less, and even more preferably 10 V or less.
  • means for controlling the potential of the low plasma potential plasma such as inductively coupled plasma to 50 V or lower, 30 V or lower, or even 10 V or lower can be provided.
  • the source gas supply device for film formation, the degree of vacuum (gas pressure) adjustment device in the film formation chamber (vacuum chamber), and the high frequency power source for plasma excitation for converting the source gas into plasma are controlled together, in other words, the source gas.
  • the plasma potential may be set to about 50 V or less, 30 V or less, or even 10 V or less by means of controlling the supply amount, the degree of vacuum in the film formation chamber, and the high-frequency power for converting the gas into plasma (power supplied to the high-frequency antenna). .
  • the lower limit of the plasma potential will be approximately 20V, and depending on the device, it will be approximately 10V.
  • the ion energy in the ion beam irradiated from the ion beam irradiation apparatus to the silicon dot formation target substrate may be determined according to the purpose of the ion beam irradiation, and the silicon dot nucleus is formed.
  • the plasma potential is P [V]
  • the ion energy at the time of ion beam irradiation with the first ion energy is preferably P [eV] or more.
  • the ion energy at the time of ion beam irradiation with the second ion energy for growing crystalline silicon dots from the nucleus is 2 keV or less, more preferably 500 eV or less.
  • P itself of P [V] and P [eV] is a numerical value.
  • the third type silicon dot formation method when the first ion energy falls below the P [eV] in the ion beam irradiation to the silicon dot formation target substrate, it is difficult to form “nuclei”. However, if it is too large, damage to the silicon dot formation target substrate may occur due to ion irradiation. To about 5 keV.
  • the silicon dots to be grown based on the “nuclei” are greatly affected by the sputtering action or collision destruction action by the ions, making it difficult to grow the silicon dots.
  • the second ion energy is 2 keV or less, more preferably 500 eV or less, there is an effect of promoting movement or migration of silicon atoms by ion irradiation, and high-quality silicon dots with high crystallinity are grown.
  • silicon dots may be difficult to grow.
  • an example of 50 eV or more can be given.
  • the ion species of the ion beam irradiated from the ion beam irradiation apparatus to the silicon dot formation target substrate are inert gas (helium (He) gas, neon (Ne) gas, argon (Ar ) Gas, krypton (Kr) gas, xenon (Xe) gas, etc.), reactive gas (hydrogen (H 2 ) gas, fluorine (F 2 ) gas, hydrogen fluoride (HF) gas, etc.) and silicon-based gas (monosilane) (SiH 4 ) gas, silicon hydride gas such as disilane (Si 2 H 6 ) gas, silicon fluoride gas such as silicon tetrafluoride (SiF 4 ) gas, silicon chloride gas such as silicon tetrachloride (SiCl 4 ) gas Etc.) can be exemplified by ions generated from at least one kind of gas.
  • inert gas helium (He) gas, neon (Ne) gas
  • the plasma source gas for example, at least one of the silicon-based gases exemplified as a gas serving as an ion species source of the ion beam, or the silicon-based gas Among these, at least one gas and at least one gas among the reactive gases can be used.
  • the temperature of the silicon dot formation target substrate for forming silicon dots can be 600 ° C. or lower (the lower limit is not limited to this, but, for example, about room temperature). Compared to the prior art, it is possible to obtain high quality silicon dots even at such a low temperature. For this reason, in the third type silicon dot formation, for example, a temperature control device that controls the temperature of the substrate supported by the substrate installation portion of the plasma generation chamber to 600 ° C. or less may be employed.
  • the number of ions / number of silicon atoms is preferably 0.01-10. This is because if the ratio is smaller than 0.01, the crystallization effect by ion irradiation may be insufficient, and if it is larger than 10, the amount of ions becomes excessive and the generation of silicon dot defects may increase. .
  • the number of silicon atoms that reach the surface of the silicon dot formation target substrate can be controlled while monitoring the silicon dot particle size, and the number of ions that reach the surface of the substrate can be extracted from the ion beam irradiation apparatus (ion source). It can be controlled by controlling the voltage or by controlling the high frequency power for generating plasma in the ion source.
  • the particle size is uniform of the silicon dots means that the particle size of each silicon dot is the same or substantially the same, and even if there is a variation in the particle size of the silicon dots. It also refers to the case where the particle diameters of silicon dots can be considered to be practically uniform.
  • the particle diameters of silicon dots are aligned within a predetermined range (for example, a range of 10 nm or less or a range of 5 nm or less) or are generally aligned,
  • the diameter is distributed in the range of 2 nm to 3 nm and the range of 5 nm to 8 nm, but as a whole, the particle size of the silicon dots is considered to be generally within a predetermined range (eg, a range of 10 nm or less). This includes cases where there is no problem in practical use.
  • “the particle size is uniform” of the silicon dots indicates a case where it can be said that the silicon dots are substantially uniform as a whole from a practical viewpoint.
  • a silicon dot forming method and a silicon dot forming apparatus capable of forming silicon dots having a uniform particle diameter on a silicon dot formation target substrate with a uniform density distribution and having a wide selectable range of substrate materials in terms of heat resistance are provided. be able to.
  • FIG. 1 shows an example of the first type silicon dot forming apparatus.
  • the silicon dot forming apparatus shown in FIG. 1 includes a plasma generation chamber 11, a flat plate type high-frequency power application electrode 12 installed in the plasma generation chamber, and a flat plate type substrate installation electrode 13 opposed thereto.
  • the plasma generation chamber 11 is grounded.
  • the electrode 12 is supported by a support member 121 made of a conductive material.
  • the support member 121 extends through the ceiling wall of the plasma generation chamber 11 to the outside.
  • the support member 121 is electrically insulated from the plasma generation chamber 11 by an insulating member 122.
  • the base electrode 13 is supported by a support member 131 made of a conductive material.
  • the support member 131 passes through the bottom wall of the plasma generation chamber 11 and extends outside the chamber.
  • the support member 131 is electrically insulated from the plasma generation chamber 11 by an insulating member 132.
  • the electrode 13 has a heater (not shown), and can heat the silicon dot formation target substrate S installed on the electrode 13.
  • a high frequency power supply device 15 is connected to the high frequency power application electrode 12 through a support member 121 and a matching box 14.
  • the high-frequency power supply device 15 includes a high-frequency power supply 151 and a switch 152 that turns on / off power supply from the power supply to the electrode 12.
  • a positive bias power supply device 16 is connected to the base electrode 13 through a support member 132.
  • the power supply device 16 includes an output variable DC power supply 161 for applying a positive bias voltage to the electrode 13 and a switch 162 for turning on / off the application of the positive bias voltage from the power supply to the electrode 13.
  • the high frequency power application electrode 12, the matching box 14, the high frequency power supply device 15 and the like constitute a plasma generating device 1A.
  • the ON / OFF of the switch 152 of the high frequency power supply device 15 and the switch 162 of the bias power supply device 16 is controlled by the control unit 17. This control will be described later with reference to FIG.
  • the output of the DC power supply 161 of the bias power supply device 16 is also controlled by the control unit 17.
  • the plasma generation chamber 11 is connected to a gas introduction device 18 for introducing a gas containing silicon into the chamber and an exhaust device 19 for exhausting the gas from the plasma generation chamber 11.
  • control unit 17 includes a trigger circuit for triggering the switches 152 and 162 to be turned on, a timing adjusting circuit for determining the timing of the switch-on operation by the trigger circuit, and the like.
  • a silicon dot formation target substrate S such as a silicon substrate is set on the substrate setting electrode 13 in the plasma generation chamber 11 and is exhausted from the chamber 11 by the exhaust device 19.
  • a gas containing silicon is introduced from the gas introduction device 18 while maintaining the inside of the chamber at a silicon dot formation pressure on the substrate S, and high frequency power is applied from the high frequency power supply device 15 to the high frequency electrode 12 under the instruction of the control unit 17 Then, while the gas is turned into plasma, a first positive pulse voltage is applied from the positive bias power supply 16 to the substrate installation electrode 13 and the substrate S installed thereon, and negative ions containing silicon in the plasma are applied to the substrate.
  • a nucleus serving as a base of silicon dots is formed on the substrate S, and then a second positive pulse voltage is applied to the substrate S from the power supply device 16 to generate plasma.
  • a second positive pulse voltage is applied to the substrate S from the power supply device 16 to generate plasma.
  • examples of the gas containing silicon supplied from the gas introducing device 18 include gases such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), and silicon tetrafluoride (SiF 4 ).
  • gases such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), and silicon tetrafluoride (SiF 4 ).
  • gases such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), silicon tetrachloride (SiCl 4 ), and silicon tetrafluoride (SiF 4 ).
  • Examples of the negative ions attracted to the substrate S include primary silane negative ions such as SiH 3 ⁇ and SiH 2 ⁇ .
  • the gas species and negative ion species containing silicon can be applied to other embodiments of the first silicon dot forming method and apparatus according to the present invention described later, and a second type silicon dot forming method described later. It can also be applied to examples of devices.
  • the controller 17 turns on / off the plasma generating apparatus 1A at a predetermined cycle. That is, when applying high-frequency power to the electrode 12, the control unit 17 turns on and off the switch 152 at a predetermined cycle as shown in the upper part of FIG. 2, and generates (lights) and extinguishes plasma at a predetermined cycle.
  • the switch 162 when applying a positive pulse voltage to the base electrode 13, the switch 162 is turned on / off at a predetermined cycle as shown in the lower part of FIG. 2, and positive bias application to the electrode 13 is turned on / off at a predetermined cycle. 13 is applied with a positive pulse voltage.
  • the positive pulse voltage is applied to the electrode 13 for a predetermined period Tb between the time when the plasma generating apparatus 1A is turned off and the period after the predetermined period Ta has elapsed until the plasma generating apparatus 1A is turned on again.
  • the positive pulse voltage is applied to the electrode 13 during a predetermined period Tb between the time when the switch 152 of the high-frequency power supply device 15 is turned off and the time after the predetermined period Ta has elapsed until the switch 152 is turned on again.
  • T is the off period of the apparatus 1A, and hence the plasma extinguishing period.
  • the negative ion density can be increased by performing plasma lighting in a pulse manner and applying a positive pulse voltage to the substrate installation electrode 13 immediately after the plasma is extinguished. More specifically, plasma is generated (lighted) from the gas introduced into the chamber 11 when the plasma generating apparatus 1A is turned on (switch 152 is turned on), and then the apparatus 1A is turned off (switch 152 is turned off). When the plasma is extinguished, the temperature of the electrons in the plasma rapidly decreases. At this time, the density of electrons and positive and negative ions hardly changes, but low-energy electrons are dominant in the plasma. The probability that negative ions are generated due to the dissociative adhesion between the low-energy electrons and the molecules increases rapidly.
  • the negative ion concentration (density) rapidly increases immediately after the plasma generating apparatus 1A is turned off. As the time further elapses, the electrons are light, so that they diffuse rapidly and disappear and the density decreases. On the other hand, since positive and negative ions have a large mass, they hardly disappear. For this reason, the electron density becomes extremely low, and a peculiar plasma (having almost no electrons) in which the plasma is maintained by positive and negative ions is formed.
  • a period Ta in which the negative ion concentration becomes sufficiently high is set as a period from the plasma extinguishing to the start of application of the positive pulse voltage to the electrode 13, and when the period Ta elapses, the electrode 13 and the substrate S installed on the electrode 13 are set.
  • a positive pulse voltage is applied during the period Tb [ ⁇ (T ⁇ Ta)], negative ions are drawn all at once at a timing at which the negative ion concentration is increased, and this operation is repeated to form silicon dots. .
  • silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.
  • the silicon dot forming pressure in the plasma generation chamber 11 for forming silicon dots is approximately 0.5 Pa to 50 Pa depending on the type of gas containing silicon used for plasma generation. can do.
  • This silicon dot formation pressure is also a pressure capable of generating plasma.
  • the silicon dot formation pressure in the chamber 11 is lower than 0.5 Pa, the dots may not grow easily or the dot growth may be slow. If it exceeds 50 Pa, crystalline silicon dots may not be obtained.
  • the frequency of the high frequency power applied to the high frequency power application electrode 12 depends on the type of gas containing silicon used for plasma generation, it is approximately 13.56 MHz to 60 MHz, and the power is 5 mW / cm 3 to 100 mW. For example, about / cm 3 .
  • the high-frequency power frequency falls below 13.56 MHz, the plasma potential increases. If it exceeds 60 MHz, the plasma may become difficult to light.
  • the electric power if it becomes smaller than 5 mW / cm 3 , the plasma density may become too low, and if it exceeds 100 mW / cm 3 , it is necessary to take measures against heat at the power introduction part to the electrode. May come.
  • the magnitude of the positive pulse voltage applied to the substrate installation electrode 13 is determined according to the purpose of ion irradiation toward the substrate S. For example, upon application of a first positive pulse voltage for ion irradiation with a first ion energy (a plasma potential of P [V] or more and 5 keV or less if the plasma potential is P [V]) that forms a nucleus serving as a silicon dot.
  • a first positive pulse voltage for ion irradiation with a first ion energy a plasma potential of P [V] or more and 5 keV or less if the plasma potential is P [V]
  • the first positive pulse voltage is about 500 V to 5 kV.
  • the positive pulse voltage is about 50 V to 2 kV (more preferably, 50 V to 500 V).
  • the substrate S may be damaged. There is.
  • the second pulse voltage drops below 50V, the value becomes equivalent to the plasma potential, and the effect of applying the second pulse voltage may not be recognized in relation to the preferable plasma potential as described above.
  • the second pulse voltage exceeds 2 kV, the growth of silicon dots may become difficult, and the crystallinity of the formed dots may deteriorate.
  • a first ion for ion irradiation with a first ion energy (for example, P [eV] or more and 5 keV or less if the plasma potential is P [V]) that forms a nucleus serving as a silicon dot is used.
  • a positive pulse voltage and a second positive pulse voltage for ion irradiation with a second ion energy for growing silicon dots from the nucleus (for example, 50 eV or more and 2 ke or less (more preferably 500 eV or less)) are obtained in advance by experiments or the like. It can be set in the control unit 17 in advance.
  • the plasma lighting period Tc can be exemplified as about 10 ⁇ sec to 500 ⁇ sec
  • the plasma extinguishing period T can be exemplified as about 500 ⁇ sec to 10 msec.
  • the period Ta from the plasma extinction to the start of positive pulse voltage application can be about 50 ⁇ sec to 200 ⁇ sec
  • the positive pulse voltage application period Tb can be about 5 ⁇ sec to 100 ⁇ sec.
  • the silicon dot forming pressure, the magnitude of the positive pulse voltage applied to the base electrode, and the periods Tc, T, Ta, and Tb described above are the other ones of the first silicon dot forming method and apparatus according to the present invention described later.
  • the present invention can also be applied to the embodiment.
  • the plasma generating apparatus 1A described above generates high-frequency plasma
  • the plasma generating apparatus is not limited thereto, and may generate microwave plasma, DC discharge plasma, or the like. Regardless of which plasma generation apparatus is employed, the plasma generation apparatus is periodically turned on and off, and a positive pulse voltage is applied to the substrate S at the same time when negative ions increase immediately after being turned off.
  • FIG. 3 shows another example of the silicon dot forming apparatus.
  • the silicon dot forming apparatus shown in FIG. 3 includes a plasma generation chamber 21, a filament 22 installed in the plasma generation chamber, and a flat plate-type substrate installation electrode 23 facing the filament.
  • a conductor rod 291 for forming a magnetic field for capturing high-energy electrons is provided between the filament 22 and the base electrode 23.
  • a plurality of conductor rods 291 are arranged in parallel at a predetermined interval.
  • the first plasma chamber 211 is above the rods 291 and the second plasma chamber 212 is below the rods 291.
  • the filament 22 penetrates the ceiling wall of the plasma generation chamber 21.
  • the filament 22 is electrically insulated from the chamber 21 by an insulating member 221.
  • the substrate installation electrode 23 is supported by a support member 231 made of a conductive material.
  • the support member 231 passes through the bottom wall of the plasma generation chamber 21 and extends outside the chamber.
  • the support member 231 is electrically insulated from the plasma generation chamber 21 by an insulating member 232.
  • a filament heating power source 241 is connected to the filament 22, and a discharge power source 242 is provided between the filament 22 and the plasma generation chamber 21, and a discharge voltage is applied from the discharge power source 242 to the plasma generation chamber 21. I can do it.
  • the power source 242 is connected to the plasma generation chamber 21 via a switch 243 that turns on / off voltage application to the plasma generation chamber 21.
  • Permanent magnets are arranged on the outside of the first plasma chamber 211 and the outside of the second plasma chamber 212 of the plasma generation chamber 21 so that N poles and S poles are alternately arranged.
  • a magnetic field (cusp magnetic field) is formed so that the plasma can be confined efficiently.
  • the filament 22, the filament heating power source 241, the discharging power source 242, the switch 243, and the like form the plasma generating apparatus 2A.
  • a positive bias power supply device 25 is connected to the substrate installation electrode 23 via a support member 231.
  • the power supply device 25 includes an output variable DC power supply 251 for applying a positive bias voltage to the electrode 23 and a switch 252 for turning on / off the application of the positive bias voltage from the power supply to the electrode 23.
  • On / off of the switch 243 and on / off of the switch 252 in the plasma generating apparatus 2A are controlled by the control unit 26 as described later.
  • the output of the DC power supply 251 of the bias power supply device 25 is also controlled by the control unit 26.
  • a gas introduction device 27 for introducing a gas containing silicon into the chamber and an exhaust device 28 for exhausting the gas from the plasma generation chamber 21 are connected to the plasma generation chamber 21.
  • a magnetic field B can be formed around each conductor rod 291 by passing a current from the power source 292 to the plurality of conductor rods 291.
  • the conductor rod 291 and the power source 292 constitute a magnetic field forming device 29 for forming an electron trapping magnetic field.
  • silicon dots can be formed as follows.
  • a silicon dot formation target substrate S such as a silicon substrate is installed on the substrate installation electrode 23 in the second plasma chamber 212.
  • a gas containing silicon is introduced from the gas introducing device 27 while the chamber is evacuated from the chamber 21 by the exhaust device 28 and maintained at a reduced pressure to form silicon dots on the substrate S, while the filament 22 is applied by the heating power source 241.
  • the switch 243 is turned on under the instruction of the control unit 26 and a positive voltage is applied from the discharge power source 242 to the plasma generation chamber 21, thereby drawing out the thermoelectrons from the heated filament 22 to the gas.
  • the plasma is generated in the first plasma chamber 211 by the collision.
  • a current in the same direction is supplied from the power source 292 of the magnetic field forming device 29 to each conductor rod 291 to form a weak magnetic field of several gauss to several tens of gauss.
  • the first positive pulse voltage is applied to the substrate installation electrode 23 and the substrate S installed on the substrate 25, and negative ions including silicon in the plasma are attracted to the substrate.
  • a nucleus serving as a base of silicon dots is formed, and then a second positive pulse voltage is applied to the substrate S from the power supply device 25 to attract negative ions including silicon in the plasma to the substrate, thereby forming the nucleus. Based on this, silicon dots can be grown.
  • the plasma formed in the first plasma chamber 211 arrives at the second plasma chamber 212 from between the conductor rods 291. At this time, high-energy electrons in the plasma generated in the first plasma chamber 211 form a magnetic field. The passage through the second plasma chamber 212 is suppressed by the magnetic field barrier formed by the device 29. Low energy electrons can travel through the magnetic field to the second plasma chamber 212. Thus, the magnetic field acts as an energy filter.
  • examples of low energy electrons that pass through the magnetic field forming device 29 and arrive at the second plasma chamber 212 are approximately 30 eV or less.
  • Low energy electrons have a large cross-sectional area of collisional bonds with neutral molecules and atoms.
  • Low energy electrons are linked to neutral radicals and negatively ionized to SiH 3 ⁇ , SiH 2 ⁇ , and the like.
  • the negative ion concentration density is increased in the second plasma chamber 212.
  • the control unit 26 turns on and off the plasma generating apparatus 2A at a predetermined cycle at the same timing as shown in FIG. 2, and also applies a positive bias voltage to the substrate installation electrode 23. Turn on and off at a predetermined timing. That is, the control unit 26 turns on and off the switch 243 in the plasma generation apparatus 2A at a predetermined cycle, and generates (lights) and extinguishes plasma at a predetermined cycle.
  • the switch 252 is turned on / off at a predetermined cycle
  • positive bias application to the electrode 23 is turned on / off at a predetermined cycle, and a positive pulse voltage is applied to the electrode 23.
  • the positive pulse voltage is applied to the electrode 23 for a predetermined period Tb between the time when the plasma generating apparatus 2A is turned off and the period after the elapse of the predetermined period Ta until the plasma generating apparatus 2A is turned on again.
  • the positive pulse voltage is applied to the electrode 23 during a predetermined period Tb between the time when the switch 243 of the plasma generating apparatus 2A is turned off and the time after the predetermined period Ta has elapsed until the switch 243 is turned on again. Made.
  • negative ions including silicon atoms are applied all at once by applying the first and second positive pulse voltages to the substrate installation electrode 23 and the substrate S installed thereon at a timing at which the negative ion concentration is sufficiently increased in the second plasma chamber 212.
  • This operation can be repeated to form a “nucleus” that becomes the basis of the silicon dot, and the silicon dot can be grown based on the nucleus.
  • silicon dots having a uniform particle diameter can be formed on the entire surface with a uniform density distribution.
  • the gas containing silicon is introduced into the first plasma chamber 211 as shown in FIG. 3, but it may be introduced into the second plasma chamber 212, or the first and second It may be introduced into both of the two plasma chambers.
  • the plasma generating apparatus 2A generates plasma using the filament 22 that emits thermoelectrons.
  • the plasma generating apparatus is not limited thereto, and other high-frequency plasma and microwave plasma are used. Etc. may be generated.
  • the electron trapping magnetic field is formed by passing a current through the conductor rod 291.
  • magnets for example, permanent magnets as shown
  • mg1 to mg4 are provided outside the unit, and the first and second magnets mg1 and mg2 and opposite magnets mg3 and mg4 face each other.
  • the electron trapping magnetic field B may be formed in the boundary region between the two plasma chambers.
  • FIG. 5 shows another example of the silicon dot forming apparatus.
  • the silicon dot forming apparatus of FIG. 5 is of a type that forms ECR plasma.
  • This apparatus includes a plasma generation chamber 31, a magnetron 32, a base installation electrode 33, and the like.
  • the magnetron 32 is connected to the plasma generation chamber 31 via a waveguide 321 and a microwave transmission window 323 made of a dielectric material.
  • An ECR coil 323 for forming a magnetic field is provided outside the plasma generation chamber 31.
  • the coil 323 is energized from a power supply (not shown) to form a longitudinal magnetic field B.
  • the magnetron 32, the waveguide 321, the dielectric window 323, the coil 323, etc. form a plasma generating device 3A.
  • the substrate installation electrode 33 is provided in the lower part of the plasma generation chamber 31 and is supported by a conductive support member 331.
  • the support member 331 extends outside through the bottom wall of the chamber 31.
  • the support member 331 is insulated from the chamber 31 by an insulating member 332.
  • a positive bias power supply device 34 is connected to the electrode 33 via a support member 331.
  • the power supply device 34 includes an output variable DC power supply 341 for applying a positive bias voltage to the electrode 33 and a switch 342 for turning on / off the application of the positive bias voltage from the power supply to the electrode 33.
  • the magnetron 32 and the on / off of the switch 342 are controlled by a control unit 35 as will be described later.
  • the output of the DC power supply 341 of the bias power supply 34 is also controlled by the control unit 35.
  • a gas introduction device 36 for introducing a gas containing silicon into the chamber and an exhaust device 37 for exhausting the gas from the plasma generation chamber 31 are connected to the plasma generation chamber 31.
  • silicon dots can be formed as follows.
  • a silicon dot formation target substrate S such as a silicon substrate is set on the substrate setting electrode 33.
  • a gas containing silicon is introduced from the gas introduction device 36 while the chamber 31 is evacuated from the chamber 31 by the exhaust device 37 and maintained at a reduced pressure to form a silicon dot on the substrate S.
  • magnetron 32 is turned on. The microwave generated by the magnetron 32 propagates through the waveguide 321, enters the plasma generating chamber 31 through the window 323, acts on the introduced gas, and turns it into plasma.
  • the switch 342 of the positive bias power supply 34 is turned on / off to apply the first positive pulse voltage to the substrate installation electrode 33 and the substrate S installed thereon, so that the silicon in the plasma
  • the switch 342 of the positive bias power supply 34 is turned on / off to apply the first positive pulse voltage to the substrate installation electrode 33 and the substrate S installed thereon, so that the silicon in the plasma
  • nuclei that are the basis of silicon dots are formed on the substrate S, and then a second positive pulse voltage is applied to the substrate S to negatively contain silicon in the plasma.
  • silicon dots are grown based on the nuclei.
  • the control unit 35 turns on and off the plasma generating device 3A at a predetermined cycle at the same timing as shown in FIG. Is also turned on and off at a predetermined timing. That is, the control unit 35 turns on and off the magnetron 32 in the plasma generating apparatus 3A at a predetermined cycle, and generates (lights on) and extinguishes plasma at a predetermined cycle.
  • the switch 342 is turned on / off at a predetermined cycle, and the positive bias application to the electrode 33 is turned on / off at a predetermined cycle. A positive pulse voltage is applied.
  • the positive pulse voltage is applied to the electrode 33 for a predetermined period Tb between the time when the plasma generating device 3A is turned off and the time after the elapse of the predetermined time period Ta until the plasma generating device 3A is turned on again.
  • the positive pulse voltage is applied to the electrode 33 during a predetermined period Tb between the time when the magnetron 32 is turned off and the time after the predetermined period Ta has elapsed until the magnetron 32 is turned on again.
  • the first and second positive pulse voltages are applied to the base electrode 33 and the base S placed thereon to apply negative ions all at once. The whole is drawn and this operation is repeated to form a “nucleus” that becomes the basis of the silicon dot, and further, the silicon dot is grown based on the nucleus.
  • silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.
  • FIG. 6 shows another example of the silicon dot forming apparatus.
  • the silicon dot forming apparatus of FIG. 6 uses a cesium-based sputter negative ion source.
  • the apparatus of FIG. 6 is disposed in the plasma generation chamber 41, the conductive sputtering target 42 disposed in the upper portion of the chamber 41, the high-frequency antenna 43 disposed in the intermediate region in the chamber 41, and the lower portion in the chamber 41.
  • a substrate mounting electrode 44 is included.
  • the sputter target 42 is supported by a conductive support member 421.
  • the support member 421 extends through the ceiling wall of the chamber 41 to the outside.
  • the support member 421 is insulated from the chamber 41 by an insulating member 422.
  • a negative bias voltage of about 300 V to 800 V can be applied to the target 42 from the negative bias power supply device 423.
  • the target 42 may have a cesium (Cs) layer formed on the surface in advance, but in this example, after the target 42 is installed in the chamber 42, cesium is vapor deposited on the target. That is, a cesium deposition device 424 is provided outside the chamber 41.
  • the apparatus 424 includes an oven 424a containing cesium (Cs) therein, a heater 424b for heating and evaporating cesium through the oven, and a duct 424c for guiding and depositing the evaporated cesium to the target 42, The apparatus 424 deposits cesium on the surface of the target 42.
  • the power supply device 45 includes a high frequency power supply 451 and a switch 452 for turning on / off application of the power supply output to the antenna.
  • the other end of the antenna 43 is grounded.
  • the antenna 43, the matching box 450, the high frequency power supply device 45, and the like constitute a plasma generation device 4A.
  • the substrate installation electrode 44 is supported by a conductive support member 441, and the support member 441 passes through the bottom wall of the chamber 41 and extends to the outside.
  • the support member 441 is insulated from the chamber 41 by an insulating member 442.
  • a positive bias power supply device 46 is connected to the electrode 44 via a support member 441.
  • the power supply device 46 includes an output variable DC power source 461 for applying a positive bias voltage to the electrode 43 and a switch 462 for turning on / off the application of the positive bias voltage from the power source to the electrode 43.
  • the switch 452 of the high frequency power supply device 45 and on / off of the switch 462 are controlled by the control unit 47 as described later.
  • the output of the DC power supply 461 of the bias power supply device 46 is also controlled by the control unit 47.
  • a gas introduction device 48 for introducing a gas containing silicon into the chamber and an exhaust device 49 for exhausting the gas from the plasma generation chamber 41 are connected to the plasma generation chamber 41.
  • silicon dots can be formed as follows.
  • a silicon dot formation target substrate S such as a silicon substrate is installed on the substrate installation electrode 44.
  • cesium is deposited on the sputter target 42 by the cesium deposition apparatus 424.
  • a negative bias voltage is applied from the bias power supply device 423 to the target 42 on which this cesium is deposited, while the exhaust device 49 exhausts the chamber 41 from the chamber 41 and keeps the chamber at a reduced pressure to form silicon dots on the substrate S.
  • a gas containing silicon is introduced from the gas introduction device 48, and the switch 452 of the high frequency power supply device 45 is turned on under the instruction of the control unit 47 to apply high frequency power from the high frequency power supply 451 to the high frequency antenna 43.
  • the gas is turned into plasma.
  • the target 42 to which cesium is deposited and a negative bias voltage is applied functions as an electron emitter.
  • the positive ions contained in the plasma are attracted to the target 42 to which a negative bias is applied, while electrons are emitted from the target 42, and the electrons are given to radicals, molecules, positive ions, etc. containing silicon, and they are Negative ionization.
  • the density (concentration) of negative ions containing silicon is increased.
  • the switch 462 of the positive bias power supply 46 is turned on and off to apply a first positive pulse voltage to the base electrode 44 and the base S placed thereon, and attract negative ions including silicon in the plasma to the base.
  • a nucleus serving as a silicon dot is formed on the substrate S, and then a second positive pulse voltage is applied from the power supply device 46 to the substrate S to attract negative ions including silicon in the plasma to the substrate.
  • silicon dots can be grown based on the nuclei.
  • the control unit 47 turns on and off the plasma generating device 4A at a predetermined cycle at the same timing as shown in FIG.
  • the application of each second positive bias voltage is also turned on / off at a predetermined timing. That is, the control unit 47 turns on / off the switch 452 in the plasma generation apparatus 4A at a predetermined cycle, and generates (lights) and extinguishes plasma at a predetermined cycle.
  • the switch 462 is turned on / off at a predetermined cycle, and the positive bias application to the electrode 44 is turned on / off at a predetermined cycle. A positive pulse voltage is applied.
  • the positive pulse voltage is applied to the electrode 44 for a predetermined period Tb between the time when the plasma generating apparatus 4A is turned off and the period after the predetermined period Ta has elapsed until the plasma generating apparatus 4A is turned on again.
  • the positive pulse voltage is applied to the electrode 44 during a predetermined period Tb between the time when the switch 452 of the high frequency power supply device 45 is turned off and the time after the predetermined period Ta has elapsed until the switch 452 is turned on again.
  • a positive pulse voltage is applied to the base body setting electrode 44 and the base body S installed thereon to attract negative ions all over the base body S.
  • the operation is repeated to form silicon dots.
  • silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.
  • FIG. 7 An example of a type of silicon dot forming apparatus is shown.
  • the silicon dot forming apparatus shown in FIG. 7 includes a plasma generation chamber 51, a silicon dot forming chamber 52 connected to the chamber 51, and a negative ion extraction electrode device 53 provided in the opening 511 of the chamber 51.
  • An ECR plasma generation device 54 is connected to the ceiling wall of the plasma generation chamber 51.
  • the ECR plasma generator 54 includes a chamber 541, an antenna 542 installed in the chamber, and a magnetic field generator 543 for forming a magnetic field that satisfies the ECR condition in the chamber 541.
  • the ECR plasma generator 54 is generated by a magnetron (not shown).
  • the microwave can be transmitted to the Anna 542 through the coaxial cable 544.
  • the chamber 541 communicates with the plasma generation chamber 51 through an electron emission port 541a provided in the chamber 541 and an opening 512 in the plasma generation chamber ceiling wall.
  • the chamber 541 is connected to a gas introduction device 55 for supplying a gas containing silicon to the chamber 541 and further to the plasma generation chamber 51.
  • the ECR plasma generation device 54 can generate microwaves in the chamber 541 under the magnetic field generated by the magnetic field forming device 543 by applying a microwave to the gas introduced from the gas introduction device 55 into the chamber 541.
  • Permanent magnets are arranged outside the plasma generation chamber 51 so that N poles and S poles are alternately arranged, thereby forming a multipolar magnetic field (cusp magnetic field) to efficiently confine the plasma. It is.
  • a discharge power source 56 is connected between the ECR plasma generator 54 and the plasma generation chamber 51 via a switch 561. When the switch 561 is turned on, a bias voltage for discharge is applied to the plasma generation chamber 51 by the power source 56. Is done.
  • the ECR plasma generation device 54, the discharge power supply 56, the switch 561, and the like constitute a plasma generation device 5A for generating a target main plasma in the plasma generation chamber 51.
  • a flat plate-type substrate installation portion 57 for installing the silicon dot formation target substrate S is arranged.
  • the base body setting part 57 is supported by a conductive support member 571.
  • the support member 571 extends through the bottom wall of the chamber 52 to the outside of the chamber.
  • the support member 571 is insulated from the chamber 52 by an insulating member 572.
  • the base body setting part 57 is grounded via a support member 571.
  • the base body setting portion 57 has a heater (not shown), and can heat the silicon dot formation target base body S placed thereon.
  • the negative ion extraction electrode device 53 faces the base body setting portion 57.
  • the electrode device 53 includes an acceleration electrode 531 close to the opening 511 of the plasma generation chamber 51, a deceleration electrode 532 outside thereof, and a ground electrode 533 outside thereof.
  • Each of the electrodes 531 to 533 is composed of a perforated plate in which a large number of holes are dispersedly formed.
  • the acceleration electrode 531 is connected to an acceleration power supply PW1 whose output is variable via a resistor R and a switch S1.
  • the deceleration electrode 532 is connected to an output variable deceleration power supply PW2 via a switch S2.
  • the switch S1 When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531.
  • the switch S ⁇ b> 2 When the switch S ⁇ b> 2 is turned on (closed), a negative voltage is applied to the deceleration electrode 532.
  • the resistor R, the switch S1, the acceleration power supply PW1, the switch S2, the deceleration power supply PW2, and the like constitute a negative ion extraction power supply device PW that applies a voltage for extracting negative ions from the plasma generation chamber 51 to the negative ion extraction electrode device 53. is doing.
  • the control unit 58 controls on / off (open / close) of the switch 561 for connecting the discharge power source 56 to the ECR plasma generation device 54 and the plasma generation chamber 51 and on / off (open / close) of the switches S1 and S2 in the negative ion extraction power supply device PW. It is controlled by.
  • the outputs of the power supplies PW1 and PW2 are also controlled by the control unit 58. Details of the control will be described later.
  • an exhaust device 59 is connected to the plasma generation chamber 51, and the exhaust device can exhaust the plasma generation chamber 51 and the chamber 541 of the ECR plasma generation device 54 to set them to the plasma generation pressure. It is possible to exhaust the silicon dot forming chamber 52 and set it to the silicon dot forming pressure.
  • silicon dots can be formed on the silicon dot formation target substrate S as follows.
  • a silicon dot formation target substrate S such as a silicon substrate is set in the substrate setting portion 57 in the silicon dot forming chamber 52.
  • the exhaust device 59 exhausts the plasma generation chamber 51, the chamber 541 of the ECR plasma generation device 54, and the silicon dot formation chamber 52.
  • the internal pressure of the chamber 51 and the chamber 541 is maintained at the plasma generation pressure and the internal pressure of the chamber 52 is maintained at the silicon dot formation pressure, and the gas containing silicon is supplied from the gas introduction device 55 to the chamber 541 and thus the plasma generation chamber 51 To introduce.
  • the ECR plasma generator 54 generates ECR plasma.
  • the switch 561 is turned on to apply a bias voltage for discharge from the discharge power source 56 to the plasma generation chamber 51.
  • a bias voltage is applied from the power source 56 to the plasma generation chamber 51, electrons and negative ions are extracted from the chamber 541 of the ECR plasma generation device 54, and the electrons drift into the plasma generation chamber 51. Colliding with the generated gas, main discharge plasma containing silicon and containing many negative ions is generated in the chamber 51.
  • the switches S1 and S2 of the negative ion extraction power supply device PW are turned on to apply a voltage for extracting negative ions to the negative ion extraction electrode device 53. More specifically, a positive acceleration voltage from the power source PW1 is applied to the acceleration electrode 531 of the electrode device 53 and a negative deceleration voltage from the power source PW2 is applied to the deceleration electrode 532 for negative ion extraction.
  • the application of the negative ion extraction voltage includes the application of the first ion extraction voltage and the subsequent application of the second ion extraction voltage.
  • the first ion extraction voltage extracts negative ions including silicon in the main discharge plasma in the chamber 51 to the silicon dot formation chamber 52 and applies the first ions to the silicon dot formation target substrate S installed in the substrate installation portion 57. It is a voltage for irradiating with energy to form a nucleus that causes silicon dot growth.
  • the second ion extraction voltage is such that negative ions including silicon in the plasma in the chamber 51 are extracted to the chamber 52, and the silicon dot formation target substrate S is irradiated with the second ion energy, so that the substrate S has the nucleus. And a voltage for growing silicon dots.
  • the negative ions containing silicon in the plasma generated in the chamber 51 are extracted from the numerous holes of the electrodes of the device to the silicon dot formation chamber 52 by the electrode device 53 to which the negative ion extraction voltage is applied as described above.
  • the substrate S is irradiated with an ion beam. By this ion beam irradiation, silicon dots having a uniform particle diameter are formed on the entire surface of the substrate S with a uniform density distribution.
  • the switches 561 and the switches S1 and S2 may be closed, and negative silicon ions may be continuously drawn to irradiate the substrate S.
  • the silicon dots are formed as follows. In this way, the concentration of negative ions including silicon in the plasma generation chamber 51 is increased, and negative ions are extracted and irradiated onto the substrate S at a timing at which the negative ion concentration is increased.
  • the control unit 58 turns on and off the plasma generating apparatus 5A at a predetermined cycle. More specifically, when the control unit 58 turns on (closes) the switch 561 and applies the discharge bias voltage from the discharge power supply 56 to the plasma generation chamber 51, the control unit 58 sets the switch 561 as shown in the upper part of FIG. The plasma is generated (lit) and extinguished in the chamber 51 at a predetermined cycle. On the other hand, when the first and second negative ion extraction voltages are applied to the negative ion extraction electrode device 53, the switches S1 and S2 are turned on and off at a predetermined cycle as shown in the lower part of FIG. The application of each negative ion extraction voltage of 2 is turned on and off at a predetermined cycle.
  • the negative ion extraction voltage is applied to the electrode device 53 when the plasma generating device 5A is turned on (the switch 561 is turned on) again after a predetermined period Ta ′ has elapsed after the plasma generating device 5A is turned off (the switch 561 is turned off).
  • the predetermined period Tb ′ is set during the period until switching. In FIG. 8, “T ′” is the off period of the apparatus 5A, and hence the plasma extinguishing period.
  • the negative ion concentration can be increased by performing plasma lighting in the plasma generation chamber 51 in a pulsed manner and applying a negative ion extraction voltage immediately after the plasma is extinguished. More specifically, when the switch 561 is turned on to generate (light) plasma in the chamber 51, and then the switch 561 is turned off to turn off the plasma, the temperature of electrons in the plasma rapidly decreases, and low energy is generated in the plasma. The electron becomes dominant. The probability that negative ions are generated due to the dissociative adhesion between the low-energy electrons and the molecules increases rapidly. Due to such dissociative adhesion, the negative ion concentration (density) rapidly increases immediately after the plasma generator 5A is turned off (the switch 561 is turned off).
  • a period Ta ′ in which the negative ion concentration becomes sufficiently high is set as a period from the plasma extinction to the start of application of the negative ion extraction voltage to the electrode device 53.
  • negative ions are supplied to the electrode device 53.
  • An extraction voltage is applied during the period Tb ′ [ ⁇ (T′ ⁇ Ta ′)], and negative ions are drawn all at once at a timing at which the negative ion concentration is increased, and this operation is repeated to form silicon dots.
  • silicon dots having a uniform particle diameter can be more reliably formed on the entire surface of the substrate S with a uniform density distribution.
  • the plasma generation pressure in the plasma generation chamber 51 for forming silicon dots is approximately 0.05 Pa to 50 Pa, although it depends on the type of gas containing silicon used for plasma generation. be able to.
  • the pressure in the silicon dot forming chamber 52 may be a pressure set in accordance with setting the internal pressure of the plasma generation chamber 51 as such. When the pressure in the chamber 51 becomes lower than 0.05 Pa, it may be difficult for the dots to grow or the dot growth may be slow. If it exceeds 50 Pa, crystalline silicon dots may not be obtained.
  • the positive bias voltage applied to the plasma generation chamber 51 by the discharge power source 56 may be about 100 V to 1 kV, although it depends on the type of gas containing silicon used.
  • the acceleration voltage applied to the acceleration electrode 531 and the deceleration voltage applied to the deceleration electrode 532 of the electrode device 53 are determined according to the purpose of ion irradiation toward the substrate S. That is, the voltage for ion extraction irradiation for forming nuclei that form the basis of silicon dots is applied under the first ion energy (for example, 500 eV or more and 5 keV or less) for nucleation. Is determined by the controller 58.
  • the voltage for ion extraction irradiation for growing silicon dots based on the nucleus is the second ion energy for the ion irradiation to grow silicon dots [for example, the first ion energy is 500 eV or more and 5 keV or less.
  • the second ion energy is 50 eV or more and 2 keV or less (more preferably 500 eV or less)].
  • Such a voltage can be obtained in advance by experiments or the like and set in the control unit 58.
  • a period substantially corresponding to about 100 Hz to 1 kHz can be given as a frequency.
  • the plasma lighting period Tc ′ can be exemplified as about 10 ⁇ sec to 500 ⁇ sec
  • the plasma extinguishing period T ′ can be exemplified as about 500 ⁇ sec to 10 msec.
  • the period Ta ′ from plasma extinguishing to the start of positive pulse voltage application can be about 50 ⁇ sec to 200 ⁇ sec
  • the positive pulse voltage application period Tb ′ can be about 5 ⁇ sec to 100 ⁇ sec.
  • the plasma generation pressure, the magnitude of the positive bias voltage applied to the plasma generation chamber, the magnitude of the voltage applied to the negative ion extraction electrode device, and the periods Tc ′, T ′, Ta ′, and Tb ′ will be described later.
  • the present invention is also applicable to other embodiments of the second silicon dot forming method and apparatus according to the present invention.
  • the plasma generation apparatus 5A described above uses electrons in the ECR plasma.
  • the plasma generation apparatus is not limited thereto, and other than that, it may generate high-frequency plasma, DC discharge plasma, or the like. Good. Regardless of which plasma generation apparatus is employed, the plasma generation apparatus is periodically turned on and off, and a negative ion extraction voltage is applied to the negative ion extraction electrode apparatus in time with the increase of negative ions immediately after being turned off.
  • FIG. 9 shows another example of the second silicon dot forming apparatus according to the present invention.
  • the silicon dot forming apparatus of FIG. 9 includes a plasma generation chamber 61, a silicon dot forming chamber 62 connected to the chamber 61, and a negative ion extraction electrode device 53 provided in an opening 613 of the chamber 61.
  • the upper part of the plasma generation chamber 61 is formed in a truncated cone shape, and a magnetron 63 is connected to the apex thereof.
  • the magnetron 63 is connected to the chamber 61 through a waveguide 631 and a microwave transmission window 632 made of a dielectric material.
  • a magnetic field forming device 633 that forms a magnetic field that satisfies the ECR condition is provided outside the upper portion of the chamber 61.
  • a conductor rod 671 for forming a magnetic field for capturing high-energy electrons is provided in the middle part of the plasma generation chamber 61.
  • a plurality of conductor rods 671 are arranged in parallel at a predetermined interval.
  • the upper side of the rods 671 is a first plasma chamber 611 and the lower side of the rod 671 is a second plasma chamber 612.
  • Permanent magnets are arranged outside the second plasma chamber 612 of the plasma generation chamber 61 so that N poles and S poles are alternately arranged, thereby forming a multipolar magnetic field (cusp magnetic field) efficiently.
  • the plasma is confined.
  • the magnetron 63, the waveguide 631, the dielectric window 632, the magnetic field forming device 633, and the like constitute a plasma generating device 6A.
  • a flat plate-type substrate installation portion 57 for installing the silicon dot formation target substrate S is arranged.
  • the base body setting part 57 is supported by a conductive support member 571.
  • the support member 571 extends through the bottom wall of the chamber 62 to the outside of the chamber.
  • the support member 571 is insulated from the chamber 62 by an insulating member 572.
  • the base body setting part 57 is grounded via a support member 571.
  • the negative ion extraction electrode device 53 faces the base body setting portion 57.
  • the electrode device 53 has the same structure as the electrode device 53 shown in FIG. 7, and includes an acceleration electrode 531, a deceleration electrode 532, and a ground electrode 533.
  • Each of the electrodes 531 to 533 is composed of a perforated plate in which a large number of holes are dispersedly formed.
  • the accelerating electrode 531 is connected to a variable power accelerating power source PW1 via a resistor R and a switch S1, and the decelerating electrode 532 is connected to a variable power deciding power source PW2 via a switch S2.
  • the switch S1 When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531.
  • the switch S ⁇ b> 2 When the switch S ⁇ b> 2 is turned on (closed), a negative voltage is applied to the deceleration electrode 532.
  • the resistor R, the switch S1, the acceleration power supply PW1, the switch S2, the deceleration power supply PW2, and the like constitute a negative ion extraction power supply device PW that applies a voltage for extracting negative ions from the plasma generation chamber 61 to the electrode device 53.
  • the on / off of the magnetron 63 and the on / off of the switches S1 and S2 in the power supply device PW are controlled by the control unit 64.
  • the outputs of the power supplies PW1 and PW2 are also controlled by the control unit 64. Details of the control will be described later.
  • the plasma generation chamber 61 is connected to a gas introduction device 65 for introducing a gas containing silicon into the chamber and to an exhaust device 66. They can be exhausted from the plasma generation chamber 61 by the exhaust device 66 and set to the plasma generation pressure, and exhausted from the silicon dot formation chamber 62 and set to the silicon dot formation pressure.
  • a magnetic field B can be formed around each conductor rod 671 by passing a current from the power source 672 to the plurality of conductor rods 671.
  • the conductor rod 671, the power source 672, and the like constitute a magnetic field forming device 67 for forming an electron trapping magnetic field.
  • silicon dots can be formed as follows.
  • a silicon dot formation target substrate S such as a silicon substrate is set on the substrate setting portion 57 in the silicon dot forming apparatus 62.
  • a gas containing silicon is generated from the gas introduction device 65 while the chamber 61 is evacuated from the chamber 61 by the evacuation device 66 and the chamber is maintained at the plasma generation pressure and the silicon dot formation chamber 62 is maintained at the silicon dot formation pressure. It introduces into the chamber 61.
  • the magnetron 63 is turned on under the instruction of the control unit 64 to generate ECR plasma in the first plasma chamber 611. Further, a current in the same direction is supplied from the power source 672 of the magnetic field forming device 67 to each conductor rod 671 to form a weak magnetic field of several gauss to several tens of gauss, and further a negative ion extraction power source under the instruction of the control unit 64
  • the switches S1 and S2 of the device PW are turned on to apply a voltage for extracting negative ions to the negative ion extracting electrode device 53. More specifically, a positive acceleration voltage from the power source PW1 is applied to the acceleration electrode 531 of the electrode device 53 and a negative deceleration voltage from the power source PW2 is applied to the deceleration electrode 532 for negative ion extraction.
  • the plasma formed in the first plasma chamber 611 comes to the second plasma chamber 672 from between the conductor rods 671. At this time, high-energy electrons in the plasma generated in the first plasma chamber 611 form a magnetic field. The passage through the second plasma chamber 612 is suppressed by the magnetic field barrier formed by the device 67. Low energy electrons can move through the magnetic field to the second plasma chamber 612. Thus, the magnetic field acts as an energy filter. Although depending on the type of gas containing silicon used for plasma generation, examples of the low-energy electrons that pass through the magnetic field forming device 67 and arrive at the second plasma chamber 612 are approximately 30 eV or less.
  • Low energy electrons have a large cross-sectional area of collisional bonds with neutral molecules and atoms.
  • Low energy electrons are linked to neutral radicals and negatively ionized to SiH 3 ⁇ , SiH 2 ⁇ , and the like.
  • the negative ion concentration density
  • Negative ions containing silicon in the plasma generated in the chamber 61 are drawn out from the numerous holes of the electrodes of the device to the silicon dot forming chamber 62 by the electrode device 53 to which a negative ion extraction voltage is applied as described above.
  • the substrate S is irradiated with an ion beam. By this ion beam irradiation, silicon dots having a uniform particle diameter are formed on the entire surface of the substrate S with a uniform density distribution.
  • the application of the negative ion extraction voltage includes the application of the first ion extraction voltage and the subsequent application of the second ion extraction voltage.
  • the first ion extraction voltage extracts negative ions containing silicon in the plasma in the first plasma chamber 611 to the silicon dot formation chamber 62, and the first ion extraction voltage is applied to the silicon dot formation target substrate S installed in the substrate installation unit 57.
  • This is a voltage for forming nuclei that are irradiated with ion energy and are the basis of silicon dot growth.
  • the second ion extraction voltage negative ions including silicon in the plasma in the chamber 61 are extracted to the chamber 62, and the silicon dot formation target substrate S is irradiated with the second ion energy, so that the substrate S has the nucleus. And a voltage for growing silicon dots. Such a voltage can be obtained in advance by experiments or the like and set in the control unit 58.
  • silicon ions may be formed by continuously extracting negative ions and irradiating the substrate S, but in this example, the plasma generation chamber 61 is formed. The concentration of negative ions including silicon inside is increased, and negative ions are extracted and irradiated onto the substrate S at a timing at which the negative ion concentration is increased.
  • the control unit 64 turns the plasma generator 6A on and off at a predetermined cycle. More specifically, when the controller 64 turns on the magnetron 63 and causes the first plasma chamber 611 to generate ECR plasma, the controller 61 turns on and off the magnetron 63 at a predetermined cycle, as shown in the upper part of FIG. Plasma is generated (lit) and extinguished in a predetermined cycle. On the other hand, when a negative ion extraction voltage is applied to the negative ion extraction electrode device 53, the switches S1 and S2 are turned on and off at a predetermined cycle as shown in the lower part of FIG. Turn it on and off.
  • the negative ion extraction voltage is applied to the electrode device 53 during a predetermined period Tb ′ between the time when the plasma generating apparatus 6A is turned off and the time after the predetermined period Ta ′ elapses until the plasma generating apparatus 6A is turned on again. Made.
  • the plasma ion generation in the plasma generation chamber 61 is performed in a pulsed manner, and the negative ion concentration can be increased by applying the negative ion extraction voltage immediately after the plasma is extinguished.
  • a period Ta ′ in which the negative ion concentration becomes sufficiently high is set as a period from the plasma extinction to the start of application of the negative ion extraction voltage to the electrode device 53.
  • negative ions are supplied to the electrode device 53.
  • An extraction voltage is applied during the period Tb ′ [ ⁇ (T′ ⁇ Ta ′)], and negative ions are drawn all at once at a timing at which the negative ion concentration is increased, and this operation is repeated to form silicon dots.
  • silicon dots having a uniform particle diameter can be more reliably formed on the entire surface of the substrate S with a uniform density distribution.
  • the gas containing silicon is introduced into the first plasma chamber 611 as shown in FIG. 9, but it may be introduced into the second plasma chamber 612, or the first and second It may be introduced into both of the two plasma chambers.
  • the plasma generator 6A generates ECR plasma. For example, as shown in FIG. 3, the plasma generator 6A generates plasma using thermionic electrons emitted by heating the filament, or high-frequency plasma. It may be generated.
  • the electron trapping magnetic field is formed by passing a current through the conductor rod 671.
  • magnets for example, permanent magnets as shown
  • mg1 to mg4 are provided outside the unit, and the first and second magnets mg1 and mg2 and opposite magnets mg3 and mg4 face each other.
  • the electron trapping magnetic field B may be formed in the boundary region between the two plasma chambers.
  • FIG. 11 shows another example of the second type silicon dot forming apparatus.
  • the silicon dot forming apparatus of FIG. 11 uses a cesium-based sputtering negative ion source.
  • the apparatus of FIG. 11 includes a plasma generation chamber 71, a silicon dot formation chamber 72 connected to the chamber 71, and a negative ion extraction electrode device 53 provided in an opening 711 of the chamber 71.
  • a sputter target 73 is provided in the upper part of the plasma generation chamber 71, and a high-frequency antenna 74 is disposed in the middle.
  • the sputter target 73 is supported by a conductive support member 731.
  • the support member 731 extends through the ceiling wall of the chamber 71 to the outside.
  • the support member 731 is insulated from the chamber 71 by an insulating member 732.
  • a negative bias voltage of about 300 V to 800 V can be applied to the target 73 from the negative bias power supply device 733.
  • the target 73 may have a cesium (Cs) layer formed on the surface in advance.
  • Cs cesium
  • a cesium deposition apparatus 424 is provided outside the chamber 71.
  • the apparatus 424 is the same as that shown in FIG. 6, and an oven 424a containing cesium (Cs) therein, a heater 424b for heating and evaporating cesium through the oven, and a target 73 for evaporating cesium.
  • a duct 424c is led to be deposited and deposited on the surface of the target 73 by the apparatus 424.
  • the power supply device 75 includes a high frequency power supply 751 and a switch 752 for turning on / off application of the power supply output to the antenna.
  • the other end of the antenna 74 is grounded.
  • the antenna 74, the matching box 750, the high frequency power supply device 75, and the like constitute a plasma generation device 7A.
  • a flat plate-type substrate installation portion 57 for installing the silicon dot formation target substrate S is arranged in the silicon dot formation chamber 72.
  • the base body setting portion 57 is the same as the base body setting portion 57 shown in FIG. With respect to the base body setting portion 57, the same reference numerals as those in FIG. 7 and the like are attached to the same parts and portions as those in the base body setting portion shown in FIG.
  • the negative ion extraction electrode device 53 faces the base body setting portion 57.
  • the electrode device 53 has the same structure as the electrode device 53 shown in FIG. 7, and includes an acceleration electrode 531, a deceleration electrode 532, and a ground electrode 533.
  • Each of the electrodes 531 to 533 is composed of a perforated plate in which a large number of holes are dispersedly formed.
  • the accelerating electrode 531 is connected to a variable power accelerating power source PW1 via a resistor R and a switch S1, and the decelerating electrode 532 is connected to a variable power deciding power source PW2 via a switch S2.
  • the switch S1 When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531.
  • the switch S ⁇ b> 2 When the switch S ⁇ b> 2 is turned on (closed), a negative voltage is applied to the deceleration electrode 532.
  • the resistor R, the switch S1, the acceleration power supply PW1, the switch S2, the deceleration power supply PW2, and the like constitute a negative ion extraction power supply device PW that applies a voltage for extracting negative ions from the plasma generation chamber 71 to the electrode device 53.
  • the on / off of each of the switches S1 and S2 in the switch 752 of the high frequency power supply device 75 and the negative ion extraction power supply device PW is controlled by the control unit 76.
  • the outputs of the power supplies PW1 and PW2 are also controlled by the control unit 76. Details of the control will be described later.
  • a gas introduction device 77 for introducing a gas containing silicon into the chamber is connected to the plasma generation chamber 71 and an exhaust device 78 is connected.
  • the exhaust device 78 can exhaust the plasma generation chamber 71 and set it to the plasma generation pressure, and exhaust the silicon dot formation chamber 72 to set the chamber 72 to the silicon dot formation pressure.
  • silicon dots can be formed as follows.
  • a base S for forming silicon dots such as a silicon substrate is placed on the base placement portion 57.
  • cesium is deposited on the sputter target 73 by the cesium deposition apparatus 424.
  • a negative bias voltage is applied from the bias power supply device 733 to the target 73 on which the cesium is deposited.
  • the exhaust device 78 evacuates the chamber 71 to maintain the chamber at the plasma generation pressure, and exhausts the chamber 72 to maintain the silicon dot formation pressure on the substrate S, while supplying silicon from the gas introduction device 77. Introducing gas containing.
  • the switch 752 of the high frequency power supply device 75 is turned on (closed) under the instruction of the control unit 76 to apply high frequency power from the high frequency power supply 751 to the high frequency antenna 74, while the switch S1 in the negative ion extraction power supply device PW, S2 is turned on (closed), and a negative ion extraction voltage is applied to the negative ion extraction electrode device 53.
  • the gas is turned into plasma. Further, the target 42 to which cesium is deposited and a negative bias voltage is applied functions as an electron emitter.
  • the positive ions contained in the plasma are attracted to the target 73 to which a negative bias is applied.
  • electrons are emitted from the target 73, and the electrons are given to radicals, molecules, positive ions, etc. containing silicon, which are negatively ionized. To do. Thus, the density (concentration) of negative ions containing silicon is increased.
  • the negative ions including silicon in the plasma generated in the chamber 71 in this way are applied to the electrode of the apparatus by the electrode apparatus 53 to which a negative ion extraction voltage is applied under the instruction of the control unit 76 as described above. These holes are drawn out to the silicon dot forming chamber 72 and irradiated onto the substrate S as an ion beam.
  • the application of the negative ion extraction voltage to the electrode device 53 includes the application of the first ion extraction voltage and the subsequent application of the second ion extraction voltage.
  • the first ion extraction voltage negative ions including silicon in the plasma in the chamber 71 are extracted to the silicon dot formation chamber 72 and applied to the silicon dot formation target substrate S installed in the substrate installation unit 57 with the first ion energy. This is a voltage for irradiating to form nuclei that cause silicon dot growth.
  • negative ions including silicon in the plasma in the chamber 71 are extracted to the chamber 72, and the silicon dot formation target substrate S is irradiated with the second ion energy, so that the substrate S has the nucleus.
  • a voltage for growing silicon dots By this ion beam irradiation, silicon dots having a uniform particle diameter are formed on the entire surface of the substrate S with a uniform density distribution.
  • Silicon dots may be formed by closing all the switches 752, S1 and S2 and continuously extracting negative ions and irradiating the substrate S, but in this example, silicon atoms in the plasma generation chamber 71 are removed. The concentration of the negative ions contained is increased, and negative ions are extracted and irradiated onto the substrate S at a timing when the negative ion concentration is increased.
  • the controller 76 turns on / off the plasma generator 7A at a predetermined cycle. More specifically, the control unit 76 turns on and off the switch 752 of the high-frequency power supply device 75 to generate (turn on) and extinguish plasma in the plasma generation chamber 71 in a predetermined cycle, as shown in the upper part of FIG. On the other hand, when applying a negative ion extraction voltage to the negative ion extraction electrode device 53, the switches S1 and S2 are turned on and off at a predetermined cycle, and negative ion extraction is turned on and off at a predetermined cycle as shown in the lower part of FIG.
  • the negative ion extraction voltage is applied to the electrode device 53 when the plasma generating device 7A is turned on again (switch 752 is turned on) after a lapse of a predetermined period Ta ′ after the plasma generating device 7A is turned off (switch 752 is turned off).
  • the predetermined period Tb ′ is set during the period until switching.
  • a period Ta ′ in which the negative ion concentration becomes sufficiently high is set as a period from the plasma extinction to the start of application of the negative ion extraction voltage to the electrode device 53.
  • a period Ta ′ elapses, negative ions are supplied to the electrode device 53.
  • An extraction voltage is applied during the period Tb ′ [ ⁇ (T′ ⁇ Ta ′)], and negative ions are drawn all at once at a timing at which the negative ion concentration is increased, and this operation is repeated to form silicon dots.
  • silicon dots having a uniform particle diameter can be more reliably formed on the entire surface of the substrate S with a uniform density distribution.
  • FIG. 12 shows an example of a third type silicon dot forming apparatus.
  • the silicon dot forming apparatus shown in FIG. 12 has a plasma generation chamber 1 ′, an exhaust device 12 ′ is connected to the chamber 1 ′, and a gas introduction for introducing a gas containing silicon into the chamber 1 ′.
  • a device 13 ' is connected.
  • a base body setting portion 11 ′ for holding the silicon dot formation target base body S is disposed in the chamber 1 ′.
  • the substrate S can be placed on the substrate installation portion 11 ′ by opening / closing the gate valve 10 ′ and a substrate transport robot (not shown).
  • the substrate installation portion 11 ' has a substrate heating heater 14'.
  • an antenna 9' is installed at a position facing the peripheral edge of the substrate S held by the substrate installation unit 11 '.
  • the opening of the antenna 9 ' is indicated by 9a' in FIG. FIG. 13 shows the antenna 9 'viewed from above.
  • the antenna 9 ′ is a double half-loop antenna here, and is formed by coupling two U-shaped conductive members 91 ′ covered with an insulator 92 ′ (here, ceramic) for suppressing capacitive coupling. .
  • One end of the antenna 9 ′ is connected to the high frequency power source 2 ′ via the matching unit 3 ′, and the other end is grounded via the capacitor 15 ′.
  • an inductively coupled plasma can be generated from the gas supplied to the chamber 1 ′ by applying an inductively coupled high frequency electric field to the gas.
  • an ion source 4 ' is provided at a position facing the substrate mounting portion 11' with the antenna 9 'interposed therebetween.
  • An ion source gas supply unit 16 ′ is connected to the ion source 4 ′, and a high frequency power source 6 ′ is connected via a matching unit 5 ′ for gas plasma conversion.
  • the ion source 4 ′ has an ion irradiation electrode device 40 ′ composed of three electrodes (acceleration electrode 41 ′, deceleration electrode 42 ′, and ground electrode 43 ′ from the back side of the ion source) for extracting ions. is doing. Between the ion irradiation electrode device 40 ′ and the ion source 4 ′, an output variable acceleration power source 7 ′ and an output variable deceleration power source 8 ′ are connected. The ion source 4 ′, the electrode device 40 ′ and the like constitute an ion beam irradiation device 400.
  • the excitation method of the ion source 4 ' is shown here as a high-frequency type, but other types such as a filament type and a microwave type can be adopted.
  • the ion irradiation electrode system is not limited to the three-electrode structure, and may be composed of other numbers of electrodes.
  • control unit 100 On / off and output of the acceleration power supply 7 ′ and the deceleration power supply 8 ′ connected to the electrode system 40 ′ in the ion beam irradiation apparatus 400 are controlled by the control unit 100. In addition to this, the control unit 100 also controls the power source 2 ', the power source 6', and the like.
  • the base S is placed in the base installation portion 11 ′, and predetermined silicon dots are formed in the chamber 1 ′ by operating the exhaust device 12 ′.
  • a gas containing silicon is introduced into the plasma generation chamber 1 ′ from the gas introduction device 13 ′ while maintaining the pressure, and an inductively coupled high-frequency electric field is applied from the high-frequency power source 2 ′ via the matching unit 3 ′ and the antenna 9 ′. Then, the introduced gas is turned into plasma, and inductively coupled plasma is generated around the position indicated by 17 'in the figure.
  • the gas containing silicon at least one gas among silicon-based gases or at least one gas among reactive gases and at least one gas among silicon-based gases is used.
  • an ion source gas is introduced into the ion source 4 ′ from the ion source gas supply section 16 ′, and high-frequency power is supplied to the ion source 4 ′ from the power source 6 ′ via the matching unit 5 ′, which is indicated by 18 ′ in the figure.
  • Plasma is generated at a position in the ion source, and ions are extracted from the plasma 18 ′ by applying a voltage for ion extraction to the ion irradiation electrode device 40 ′ by the power supplies 7 ′ and 8 ′, thereby opening the antenna 9 ′.
  • the substrate S is irradiated with the ion beam through 9a ′.
  • an ion source gas ions of at least one of an inert gas, a reactive gas, and a silicon-based gas are used.
  • Voltage application for extracting ions from the power supplies 7 ′ and 8 ′ to the ion irradiation electrode device 40 ′ is performed as follows under the instruction of the control unit 100. That is, the silicon dot is formed on the silicon dot formation target substrate S so that the ion beam is irradiated with the first ion energy for forming the nucleus serving as the silicon dot. A voltage for extracting ions is applied from the power sources 7 'and 8' to the ion irradiation electrode device 40 'so that ion beam irradiation is performed with the second ion energy for growth.
  • the first ion energy for forming nuclei is P [eV] or more and about 5 keV when the plasma potential is P [V]
  • the second ion energy for growing silicon dots is 2 keV or less. It is up to about 50 eV.
  • the voltage to be applied from the power sources 7 ′ and 8 ′ to the electrode device 40 ′, or from the power sources 7 ′ and 8 ′ to perform the ion beam irradiation with the second ion energy is obtained in advance by experiments or the like and set in the control unit 100.
  • crystalline silicon dots are formed on the substrate S.
  • the pressure in the plasma generation chamber 1 ' is adjusted so that the pressure in the plasma generation chamber 1', particularly in the vicinity of the surface of the substrate S, is in the range of 0.6 Pa to 1.3 Pa.
  • the temperature of the substrate S is kept at RT (room temperature) to 600 ° C. by the heater 14 '.
  • the inductively coupled plasma 17 ′ is generated from the source gas containing silicon, the substrate S is placed under the inductively coupled plasma, and the ion beam is applied to the surface of the substrate S. Irradiation forms silicon dots.
  • the plasma generated from the gas containing silicon is the inductively coupled plasma 17 ′, and the inductively coupled plasma 17 ′ has a higher plasma density and a lower plasma potential than the electrostatically coupled plasma as described above. . Therefore, a silicon dot having high crystallinity can be obtained on a substrate having a relatively low heat resistance such as a low-melting glass substrate at a low temperature (for example, 600 ° C. or less) that can suppress thermal damage to the substrate. it can.
  • the surface of the substrate S is irradiated with an ion beam from the ion source 4 ′, so that the movement or migration of silicon atoms is promoted.
  • the crystallinity of the silicon dots becomes higher. It is not necessary to perform a separate heat treatment to increase crystallinity after the formation of silicon dots. In this way, high-quality crystalline silicon dots can be obtained with high productivity.
  • Silicon dot formation by the silicon dot formation apparatus shown in FIG. 7 ⁇ Silicon dot formation conditions> 1) Plasma conditions (high frequency plasma) ECR plasma conditions Microwave 2.45 GHz, magnetic field 875 Gauss Voltage for ion extraction applied to electrode device 53 from power sources PW1 and PW2 Voltage to obtain first ion energy 50 eV and second in-on energy 200 eV Source gas SiH 4 gas and hydrogen Gas (SiH 4 10%) Silicon dot forming pressure 0.05Pa ⁇ 1Pa Plasma extinguishing period T '500 ⁇ sec Plasma lighting period Tc '500 ⁇ sec Application of negative ion extraction voltage Application start Ta ′ 100 ⁇ sec Application period Tb ′ 100 ⁇ sec 2) Substrate Silicon wafer 3) Substrate temperature 300 ° C ⁇ Evaluation of silicon dots> When the crystallinity of the silicon dots [crystalline / (crystalline + amorphous)] was measured by analysis by laser Raman spectroscopy, high-quality silicon dots with a crystallin
  • Silicon dot formation by the silicon dot formation apparatus shown in FIG. 12 ⁇ Silicon dot formation conditions> 1) Plasma conditions (inductively coupled plasma) Excitation method High frequency power 13.56 MHz, 35 mW / cm 3 Source gas SiH 4 gas and hydrogen gas (SiH 4 10%) Silicon dot forming pressure 0.6 Pa to 1.3 Pa Plasma potential 23V Plasma density 6 ⁇ 10 10 ions / cm 3 2) Ion beam irradiation conditions First ion energy 500 eV Second ion energy 50eV 3) Substrate Non-alkali glass substrate 4) Substrate temperature 300 ° C ⁇ Evaluation of silicon dots> When the crystallinity of the silicon dots [crystalline / (crystalline + amorphous)] was measured by analysis by laser Raman spectroscopy, high-quality silicon dots with a crystallinity of 97% or more were confirmed.
  • the present invention can be used to form silicon dots having a small particle diameter used as an electronic device material such as a single electronic device or a light emitting material.

Abstract

L'invention porte sur un procédé de formation de points de silicium pour former des points de silicium de diamètres réguliers dans une distribution de masse volumique homogène sur un substrat objet sur lequel des points de silicium doivent être formés, le procédé comprenant une large plage de sélection du matériau de substrat en termes de résistance thermique ; et sur un appareil de formation de points de silicium pour réaliser le procédé. Un gaz contenant du silicium est introduit dans une chambre de génération de plasma, et un plasma est généré à partir du gaz par un dispositif de génération de plasma. Une première tension d'impulsion positive est appliquée à une électrode à montage sur substrat, de telle sorte que le substrat sur l'électrode est irradié par des ions négatifs contenant du silicium par une première énergie ionique, pour ainsi générer des noyaux. Ensuite, une seconde tension d'impulsion positive est appliquée à l'électrode, de telle sorte que le substrat est irradié par les ions négatifs contenant les ions de silicium par une seconde énergie ionique, amenant ainsi les points de silicium à se développer sur la base des noyaux.
PCT/JP2009/050630 2009-01-19 2009-01-19 Procédé de formation de points de silicium et appareil de formation de points de silicium WO2010082345A1 (fr)

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