WO2010082345A1

WO2010082345A1 - Silicon-dot forming method, and silicon-dot forming apparatus

Info

Publication number: WO2010082345A1
Application number: PCT/JP2009/050630
Authority: WO
Inventors: 司林; 敦志東名; 建治加藤; 英治高橋; 隆司三上
Original assignee: 日新電機株式会社
Priority date: 2009-01-19
Filing date: 2009-01-19
Publication date: 2010-07-22
Also published as: JPWO2010082345A1

Abstract

Disclosed are a silicon-dot forming method for forming silicon-dots of regular diameters in a homogeneous density distribution over an object substrate on which silicon dots are to be formed, wherein the method includes a wide range of selecting the substrate material in terms of heat resistance; and a silicon-dot forming apparatus for performing the method. A silicon-containing gas is introduced into a plasma-generating chamber, and plasma is generated from the gas by a plasma-generating device. A first positive pulse voltage is applied to a substrate-mounting electrode so that the substrate on the electrode is irradiated with negative ions containing silicon by a first ion energy, thereby to generate nuclei. Next, a second positive pulse voltage is applied to the electrode so that the substrate is irradiated with the negative ions containing the silicon ions by a second ion energy, thereby to cause the silicon dots to grow on the basis of the nuclei.

Description

Silicon dot forming method and silicon dot forming apparatus

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.

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).
In this method, 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

However, among the conventional silicon dot formation methods, 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.

In the CVD method, 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.

Accordingly, 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.

[1] First knowledge
(1) 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 )) is converted into plasma, and the plasma By irradiating a silicon dot formation target substrate on a substrate-installed electrode to which a bias is applied with ions containing silicon therein, nuclei that are the basis of silicon dots can be formed.

(2) At this time, there are positive ions and negative ions in the silicon-containing ions generated in the plasma. 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.

(3) When a negative bias is applied to the substrate mounting electrode and positive ions are irradiated to the silicon dot formation target substrate, there are multiple types of positive ions to be irradiated and each has a different mass. There is a tendency for the particle size and distribution to be uneven.

(4) In order to solve this problem, it is necessary to selectively separate only positive ions of a predetermined mass toward the silicon dot formation target substrate by mass separation, which requires an expensive and bulky mass separation device. In addition, 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 large area of the substrate, and it takes time to form silicon dots over a large area. .

(5) On the other hand, there are no stable negative ions including silicon other than primary silane negative ions such as SiH ₃ ⁻ and SiH ₂ ⁻ . Even when higher order silane negative ions are generated, their lifetime is extremely short, they dissociate immediately, and the negative ions are essentially only primary silane negative ions.
When the polymerization proceeds in plasma and fine particles are generated, the fine particles may be negatively charged by electron collision, but there are no negatively charged fine particles under plasma conditions with a low collision probability.

(6) Therefore, if a positive bias is applied to the substrate installation electrode in a pulsed manner and substantially the same type of negative ions is irradiated to the silicon dot formation target substrate in a lump, there is no need for a mass separator or a scanning mechanism. In addition, 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.

[2] Second knowledge
(1) 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 )) is converted into plasma, and the plasma If ions containing silicon therein are extracted using an ion extraction electrode device and irradiated onto a silicon dot formation target substrate, a nucleus serving as a basis for silicon dots can be formed.

(2) At that time, there are positive ions and negative ions in the silicon-containing ions generated in the plasma, but as described above, multiple types of positive ions are generated.

(3) When the positive ions are extracted and irradiated to the silicon dot formation target substrate, there are multiple types of positive ions to be irradiated, and the masses are different, so the particle size and distribution of the formed silicon dots tend to be uneven. There is.

(4) To solve this problem, 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.

(6) Therefore, if 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 In addition, 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.

[3] Third knowledge
(1) 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 )) is converted into plasma, and the plasma By exposing the substrate to which silicon dots are to be formed and irradiating the substrate with an ion beam, silicon dots can be formed even when the substrate temperature is 600 ° C. or lower.

(2) At this time, it is important that the plasma is a plasma having a low plasma potential such as inductively coupled plasma.
Generally speaking, the types of plasma include low-potential plasma such as inductively coupled plasma and electrostatically coupled plasma (capacitively coupled plasma).
However, in silicon dot formation by 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.

If 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. In addition, when 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.

(3) These weak points of silicon dot formation by electrostatic coupling plasma can be overcome by increasing the temperature of the substrate on which the silicon dots are formed. For example, the substrate is a low-cost substrate such as a low-melting glass substrate. When is used, it is difficult to form crystalline silicon dots on the substrate because the temperature of the substrate cannot be so high.

(4) On the other hand, 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.

(5) In order to further improve the crystallinity of silicon dots, when forming silicon dots on a silicon dot formation target substrate under a low plasma potential plasma such as inductively coupled plasma, 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.

Based on the first knowledge, 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.

[1] 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. Forming nuclei for silicon dot growth on the silicon dot formation target substrate;
Subsequent to the nucleation, a second positive pulse voltage is applied to the substrate installation electrode to irradiate the silicon dot formation target substrate with negative ions containing silicon in the plasma with the second 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. Applying a first positive pulse voltage to form a nucleus to become, and irradiating the silicon dot formation target substrate with negative ions containing silicon in the plasma with a second ion energy, based on the nucleus A silicon dot forming device which is a power supply device for applying a second positive pulse voltage for growing silicon dots.

[2] 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 Preparing a silicon dot forming chamber in which a substrate placement portion for placing a target substrate is disposed, and a negative ion extraction electrode device provided in an opening facing the substrate placement portion of the plasma generation chamber;
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. Introducing and generating plasma from the gas by the plasma generator,
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. Application of a first negative ion extraction voltage for forming nuclei for silicon dot growth upon irradiation with negative ions containing silicon in the plasma to the silicon dot formation target substrate at a second 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.

[3] Third Silicon Dot Forming Method 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. Letting
Exposing the silicon dot formation target substrate placed in the base placement portion to the plasma and irradiating the silicon dot formation target substrate from the ion beam irradiation apparatus to the silicon dot formation target,
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. A silicon dot forming method for forming silicon dots on the silicon dot formation target substrate by performing ion beam irradiation with second ion energy for growth.

It is a figure which shows schematic structure of one example of the 1st silicon dot formation apparatus which concerns on this invention. It is a figure which shows the timing of plasma lighting / extinguishing and a positive bias pulse voltage application to a base | substrate installation electrode. 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 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 | adopted with the apparatus of FIG. 12 from the top.

Explanation of symbols

S Silicon dot formation target substrate 2A Plasma generation device 1A Plasma generation device 21 Plasma generation chamber 11 Plasma generation chamber 211 First plasma chamber 12 High-frequency power application electrode 212 Second plasma chamber 13 Substrate installation electrode 22 Filament 14 Matching box 23 Substrate installation electrode DESCRIPTION OF SYMBOLS 15 High frequency power supply device 241 Filament heating power supply 151 High frequency power supply 242 Discharge power supply 152 Switch 243 Switch 16 Positive bias power supply device 25 Positive bias power supply device 161 DC power supply 251 DC power supply 162 Switch 252 Switch 17 Control unit 26 Control unit 18 Gas introduction device 27 Gas introduction device 19 Exhaust device 28 Exhaust device 2 9 Magnetic field generator 291 Conductor bar 292
mg1 ~ mg4 Magnet B Electron capture magnetic field

3A Plasma generator

4A Plasma generator 31 Plasma generator chamber 41 Plasma generator chamber 32 Magnetron 42 Sputter target 33 Substrate installation electrode 423 Negative bias power source device 321 Waveguide 424 Cesium deposition device 322 Microwave transmission window 424a Cesium containing oven 323 ECR coil 424b Heater 33 Substrate installation electrode 424c Duct 34 Positive bias power supply device 43 High frequency antenna 341 DC power supply 44 Substrate installation electrode 342 Switch 45 High frequency power supply device 35 Control unit 450 Matching box 36 Gas introduction device 451 High frequency power supply 37 Exhaust device 452 Switch 46 Positive bias Power supply 461 DC power supply 462 Switch 47 Control article 48 Gas introduction device 49 Exhaust device

51 plasma generation chamber 61 plasma generation chamber 511 opening 611 first plasma chamber 512 opening in ceiling wall 612 second plasma chamber 52 silicon dot formation chamber 613 opening 53 negative ion extraction electrode device 62 silicon dot formation chamber 531 acceleration electrode 6A plasma Generation device 532 Deceleration electrode 63 Magnetron 533 Ground electrode 631 Waveguide PW Negative ion extraction power supply device 632 Microwave transmission window R resistance 633 Magnetic field forming device PW1 Acceleration power supply 64 Control unit PW2 Deceleration power supply 65 Gas introduction device S1, S2 Switch 66 Exhaust Apparatus 5A Plasma generator 67 Magnetic field generator 54 ECR plasma generator 671 Conductor bar 541 Chamber 672 Power supply 541a Electron emission hole 442 Antenna 543 Magnetic field forming device 544 Coaxial cable 55 Gas introduction device 56 Power supply for discharge 561 Switch 57 Base installation unit 58 Control unit 59 Exhaust device

71 Plasma generation chamber 1 'Plasma generation chamber 711 Opening 10' Gate valve 72 Silicon dot formation chamber 11 'Substrate installation portion 73 Sputter target 12' Exhaust device 74 High-frequency antenna 13 'Gas introduction device 733 Negative bias power supply device 14' Substrate heating Heater 750 matching box 9 'antenna

7A plasma generator

9a antenna opening 75 high frequency power supply 92' insulator 92 '
751 High-frequency power supply 91 'U-shaped conductive member 752 Switch 2' High-frequency power supply 76 Control unit 3 'Matching device 77 Gas introduction device 15' Capacitor 78 Exhaust device 400 Ion beam irradiation device 4 'Ion source 16' Ion source gas Supply unit 5 'Matching device 6' High frequency power supply 40 'Ion irradiation electrode system 41' Acceleration electrode 42 'Deceleration electrode 43' Ground electrode 7 'Acceleration power supply 8' Deceleration power supply 100 Control unit

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.

[1] 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. Forming nuclei for silicon dot growth on the silicon dot formation target substrate;
Subsequent to the nucleation, a second positive pulse voltage is applied to the substrate installation electrode to irradiate the silicon dot formation target substrate with negative ions containing silicon in the plasma with the second ion energy. A silicon dot forming method including growing silicon dots on the silicon dot formation target substrate based on the nucleus.

(2) First Type Silicon Dot Forming Device 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. Applying a first positive pulse voltage to form a nucleus to become, and irradiating the silicon dot formation target substrate with negative ions containing silicon in the plasma with a second ion energy, based on the nucleus It is a silicon dot forming device which is a power supply device for applying a second positive pulse voltage for growing silicon dots.

According to the first type silicon dot forming method and apparatus, 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.

Also, 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. *

In the first type of silicon dot forming method and apparatus, in the irradiation of negative ions containing silicon to the silicon dot formation target substrate, 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). An example can be given. Here, “P” itself in P [V] and P [eV] is a numerical value.

If the first ion energy falls below P [eV] when the plasma potential is P [V], formation of the “nucleus” may become difficult. For this reason, it is desirable to set it to P [eV] or more, but if it is too large, damage to the silicon dot formation target substrate will occur due to ion irradiation, and an example of up to about 5 keV can be given.

When the second ion energy exceeds 2 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. On the other hand, when 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. However, if 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.

When forming silicon dots having a uniform particle size with a uniform density distribution on a silicon dot formation target substrate, it is better that the plasma contains more negative ions containing silicon. In other words, it is better that the negative ion concentration in the plasma is higher.

The following three methods can be exemplified as methods for increasing the negative ion concentration (negative ion density).
(1) 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. Due to such dissociative adhesion, 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.

By utilizing this phenomenon, the concentration of negative ions containing silicon can be increased.
Method 1 can be used in combination with Method 2 and Method 3 described later.

(2) Method 2 to increase negative ion concentration
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. In 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.

(3) Method 3 to increase negative ion concentration
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. 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.

Therefore, in the first type of silicon dot forming method, 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 | generation apparatus is turned on again after progress for a predetermined period after switching.

Further, in the first type silicon dot forming apparatus, 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. A silicon dot forming apparatus provided with

Further, in the first type silicon dot forming method, 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. Is 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 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. Or a silicon dot forming apparatus capable of increasing the concentration of negative ions, including.

In this way, in the method and apparatus using the method 2, “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.

In the first type silicon dot forming method, 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.

In order to use the method 3, 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. And 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.

[2] 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. Introducing and generating plasma from the gas by the plasma generator,
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.

(2-2) Second type silicon dot forming device 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 a first ion energy. Application of a first negative ion extraction voltage for forming nuclei for silicon dot growth upon irradiation with negative ions containing silicon in the plasma to the silicon dot formation target substrate at a second ion energy This is a silicon dot forming apparatus that is a power supply device that applies a second negative ion extraction voltage for growing silicon dots based on the nuclei.

Also with the second type silicon dot forming method and apparatus, 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.
In addition, 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.

In the second type silicon dot forming method and apparatus, when the plasma potential is P [V] in the irradiation of negative ions containing silicon to the silicon dot formation target substrate, 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. Example).
Here, “P” itself of P [V] and P [eV] is a numerical value.

As in the case of the first type silicon dot forming method and apparatus described above, when the first ion energy falls below P [eV] when the plasma potential is P [V], negative ion ions Since it becomes difficult to accelerate and the formation of “nuclei” may become difficult, it is desirable to set P [eV] or more for the formation of “nuclei”. Since damage to the target substrate due to ion irradiation occurs, an example of up to about 5 keV can be given.

Also in 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.

Also in the case of the second type silicon dot forming method and apparatus, the above-described

methods

1, 2 and 3 can be used as a method for increasing the negative ion concentration.

Therefore, in the second type silicon dot forming method, 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.

In addition, in order to use the method 1, 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.

In the second type silicon dot forming method, 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.

In order to use the method 2, 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 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. Or a silicon dot forming apparatus capable of increasing the concentration of negative ions containing silicon chamber.

In this way, in the method and apparatus using the method 2, “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.

Further, in the second type silicon dot formation method, a conductive target in which at least one substance selected from cesium, rubidium, potassium and barium is deposited in advance in the plasma generation chamber so that the method 3 can be used. Providing a negative voltage to the conductive target in plasma generation from the gas containing silicon by the plasma generation apparatus in the plasma generation chamber, and bringing positive ions in the plasma into contact with the target; You may make it raise the density | concentration of the negative ion containing a silicon | silicone inside.

In order to use the method 3, 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. And 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.

[3] Third type silicon dot formation method 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. Letting
Exposing the silicon dot formation target substrate placed in the base placement portion to the plasma and irradiating the silicon dot formation target substrate from the ion beam irradiation apparatus to the silicon dot formation target,
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.

Also by the third type silicon dot formation method, 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.

Also, 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.

According to the third type silicon dot forming method, 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.

Thus, 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.

In addition, when forming silicon dots on a substrate under a plasma having a low plasma potential such as inductively coupled plasma, 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.

Thus, according to the third type method, high-quality crystalline silicon dots can be obtained with high productivity. The silicon dots thus obtained are of high quality with high crystallinity.

In addition, according to the third type silicon dot formation method, in the ion beam irradiation, 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.

Further, according to the third type silicon dot forming method, for example, 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.

In the third type silicon dot formation method, in order to stably obtain silicon dots with high crystallinity, it is desirable that 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.

If 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. Thus, 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.

For controlling the plasma density, 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 ).

In addition, in the third type silicon dot forming method, it is desirable that 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.
For this purpose, 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.

For example, 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). .
However, when considering a structurally and costly device that can be used for forming silicon dots today, the lower limit of the plasma potential will be approximately 20V, and depending on the device, it will be approximately 10V.

In the third type silicon dot forming method, 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. When 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.
Here, “P” itself of P [V] and P [eV] is a numerical value.

In 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.

When the second ion energy exceeds 2 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. On the other hand, when 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.

However, if 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.

In the third type silicon dot forming method, 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.

Further, in the third type silicon dot forming method, as 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.

Further, in the third type silicon dot forming method, 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.

In the third type silicon dot forming method, the ratio of the number of ions irradiated from the ion beam irradiation apparatus to the substrate with respect to the number of silicon atoms reaching the substrate surface from the low plasma potential plasma such as the inductively coupled plasma 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.

In any case, “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.

For example, even if it is considered that 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, For example, 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. In short, “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.

Thus, 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.

Hereinafter, an example of a silicon dot forming method and apparatus will be described with reference to the drawings.
[1] Example of the first type silicon dot forming method and apparatus (see FIGS. 1 to 6)
(1-1) Silicon Dot Formation by Silicon Dot Forming Apparatus Shown in FIG. 1 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.

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.

In addition to the above, 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.

Although not shown, the 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.

According to the silicon dot forming apparatus shown in FIG. 1, 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. By pulling, 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. By attracting negative ions comprising silicon to the substrate, it is possible to grow silicon dots by the nucleic based.

Here, 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 ). Can be mentioned.
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. On the other hand, 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. In other words, 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. Made.
In FIG. 2, “T” is the off period of the apparatus 1A, and hence the plasma extinguishing period.

In this way, 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.

Due to such dissociative adhesion, 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.

Therefore, 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. .
Thus, silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.

As described above, 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.
When 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.

Furthermore, although 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 .
When 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.
As for 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. Here, the first positive pulse voltage is about 500 V to 5 kV.

When applying a second positive pulse voltage for ion irradiation with a second ion energy [50 eV or more and 2 keV or less (more preferably 50 eV or more and 500 eV or less)] for growing silicon dots from the nucleus, here, The positive pulse voltage is about 50 V to 2 kV (more preferably, 50 V to 500 V). *

If the first positive pulse voltage falls below the voltage corresponding to the plasma potential, it may become difficult to form “nuclei”, and if it exceeds 5 kV, the substrate S may be damaged. There is. When 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. . On the other hand, when the second pulse voltage exceeds 2 kV, the growth of silicon dots may become difficult, and the crystallinity of the formed dots may deteriorate.

Generally speaking, 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.

In addition, as the period when the plasma is turned on and off periodically, for example, from the viewpoint of improving the generation efficiency of negative ions including silicon, a period corresponding to about 100 Hz to 1 kHz as a frequency can be given.
As a specific example, the plasma lighting period Tc can be exemplified as about 10 μsec to 500 μsec, and the plasma extinguishing period T can be exemplified as about 500 μsec to 10 msec.
The period Ta from the plasma extinction to the start of positive pulse voltage application can be about 50 μsec to 200 μsec, and the positive pulse voltage application period Tb can be about 5 μsec to 100 μsec.

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.

Although 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.

(1-2) Silicon dot formation by the silicon dot forming apparatus shown in FIG. 3 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.

In addition to the above, 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.
In addition, 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.

According to the silicon dot forming apparatus shown in FIG. 3, 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. Then, 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.

Further, 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. On the substrate S, 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.

Although depending on the type of gas containing silicon used for plasma generation, 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.

Thus, there are many low-energy electrons in the plasma in the second plasma chamber 212. 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 212 from the first plasma chamber 211. Thus, the negative ion concentration (density) is increased in the second plasma chamber 212.

Although not necessarily required, in this example, 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. On the other hand, when a positive bias voltage is applied to the base electrode 13, 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. In other words, 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.

Thus, 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. Thus, silicon dots having a uniform particle diameter can be formed on the entire surface with a uniform density distribution.

In the silicon dot formation described above, 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. However, the plasma generating apparatus is not limited thereto, and other high-frequency plasma and microwave plasma are used. Etc. may be generated.

In the silicon dot forming apparatus and method shown in FIG. 3, the electron trapping magnetic field is formed by passing a current through the conductor rod 291. However, as shown in FIG. Apart from the magnet that creates the cusp magnetic field, 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.

(1-3) Silicon dot formation by the silicon dot forming apparatus shown in FIG. 5 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.

In addition to the above, 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.

According to the silicon dot forming apparatus shown in FIG. 5, 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. And 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.

Further, under the instruction of the control unit 35, 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 By attracting negative ions that contain silicon to the substrate, 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. By attracting ions to the substrate, silicon dots are grown based on the nuclei.

At this time, although not necessarily required, in this example, 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. On the other hand, when the first and second positive bias voltages are applied to the base electrode 33, 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. In other words, 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.

Thus, at the timing when the negative ion concentration (density) is increased in the plasma generation chamber 31, 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.
Thus, silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.

(1-4) Silicon dot formation by the silicon dot forming apparatus shown in FIG. 6 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.

One end of the high frequency antenna 43 is connected to the high frequency power supply device 45 through the matching box 450. 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.

In addition to the above, 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.

According to the silicon dot forming apparatus shown in FIG. 6, 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. Further, cesium is deposited on the sputter target 42 by the cesium deposition apparatus 424. Then, 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. At the same time, 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. When high frequency power is applied to the high frequency antenna 43, 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.

Thus, 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. Thus, the density (concentration) of negative ions containing silicon is increased.
Then, 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. Then, 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. Thus, silicon dots can be grown based on the nuclei.

At this time, although not necessarily required, in this example, 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. On the other hand, when applying the first and second positive bias voltages to the base electrode 44, 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. In other words, 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. Made.

Thus, at the timing when the negative ion concentration (density) is sufficiently increased in the plasma generation chamber 41, 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.
Thus, silicon dots having a uniform particle diameter can be formed on the entire surface of the substrate S with a uniform density distribution.

[2] Example of Second Type Silicon Dot Forming Method and Apparatus (See FIGS. 7 to 11) (2-1) Silicon Dot Formation by Silicon Dot Forming Apparatus Shown in FIG. 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.

In the silicon dot forming chamber 52, 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. In this example, 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. When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531. 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.

In addition to the above, 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.

According to the silicon dot forming apparatus shown in FIG. 7, silicon dots can be formed on the silicon dot formation target substrate S as follows.

First, 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. Then, 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. By the exhaust operation, 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.

Further, under the instruction of the control unit 58, 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. When the switch 561 is turned on and 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.

Further, under the instruction of the control unit 58, 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.

In forming the silicon dots, 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. In this example, 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.

That is, 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.

Thus, 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). 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.

Therefore, 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. When the 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. Form.
Thus, 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.

As described above, 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.

In addition, as the period when the plasma is turned on and off periodically, from the viewpoint of improving the generation efficiency of negative ions including silicon, for example, a period substantially corresponding to about 100 Hz to 1 kHz can be given as a frequency.
Specifically, the plasma lighting period Tc ′ can be exemplified as about 10 μsec to 500 μsec, and the plasma extinguishing period T ′ can be exemplified as about 500 μsec to 10 msec.
The period Ta ′ from plasma extinguishing to the start of positive pulse voltage application can be about 50 μsec to 200 μsec, and the positive pulse voltage application period Tb ′ can be about 5 μsec to 100 μsec.

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. However, 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.

(2-2) Silicon Dot Formation by Silicon Dot Forming Apparatus Shown in FIG. 9 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.

In the silicon dot forming chamber 62, 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. S

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. When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531. 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.

In addition to the above, 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.

In addition, 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.

According to the silicon dot forming apparatus shown in FIG. 9, 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.

Further, 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.

Thus, there are many low energy electrons in the plasma in the second plasma chamber 612. 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 612 from the first plasma chamber 611. Thus, in the second plasma chamber 612, the negative ion concentration (density) is increased.

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.

More specifically, 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.
In 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.

While the magnetron 63 is continuously operated and all the switches S1 and S2 are closed, 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.

That is, 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.
Thus, 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.

In the silicon dot formation described above, 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.

In the silicon dot forming apparatus and method shown in FIG. 9, the electron trapping magnetic field is formed by passing a current through the conductor rod 671. However, as shown in FIG. Apart from the magnet that creates the cusp magnetic field, 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.

(2-3) Silicon dot formation by the silicon dot forming apparatus shown in FIG. 11 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. In this example, after the target 73 is installed in the chamber 71, cesium is vapor deposited on the target. That is, 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.

One end of the high frequency antenna 74 is connected to the high frequency power supply device 75 via the matching box 750. 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.

In the silicon dot formation chamber 72, a flat plate-type substrate installation portion 57 for installing the silicon dot formation target substrate S is arranged. 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 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. When the switch S1 is turned on (closed), a positive high voltage is applied to the acceleration electrode 531. 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.

In addition to the above, 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.

According to the silicon dot forming apparatus shown in FIG. 11, 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. Further, cesium is deposited on the sputter target 73 by the cesium deposition apparatus 424. Then, 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.

On the other hand, 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.

By applying high frequency power to the high frequency antenna 74, 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. On the other hand, 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.

More specifically, 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.
In 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.
In the second ion extraction voltage, 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. And 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.

Thus, the plasma ion generation in the plasma generation chamber 51 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. Therefore, 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. When the 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. Form.
Thus, 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.

[3] Example of Third Type Silicon Dot Forming Method and Apparatus (See FIGS. 12 and 13) 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.

In the chamber 1 ′, a base body setting portion 11 ′ for holding the silicon dot formation target base body S is disposed. 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'.

In the chamber 1 ', 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 ′. Thus, 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.

As shown in FIG. 12, 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.

Here, 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.

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.

In forming silicon dots using the silicon dot forming apparatus shown in FIG. 12, 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.

As 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.

Further, 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 ′. As 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.

Here, the first ion energy for forming nuclei is P [eV] or more and about 5 keV when the plasma potential is P [V], and the second ion energy for growing silicon dots is 2 keV or less. It is up to about 50 eV.
In order to perform ion beam irradiation with the first ion energy, 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. The voltage to be applied to the device 40 ′ is obtained in advance by experiments or the like and set in the control unit 100.

In this way, crystalline silicon dots are formed on the substrate S. During the formation of silicon dots, 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 '.

According to the film forming method and the film forming apparatus described above, 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.

Further, when forming silicon dots on the substrate S under the inductively coupled plasma 17 ′, 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.

[4] Experiments Next, experimental examples of silicon dot formation using the silicon dot forming apparatus shown in FIGS. 1, 7, and 12 will be described.
(4-1) Silicon dot formation by the silicon dot forming apparatus shown in FIG.
1) Plasma conditions (high frequency plasma)
High frequency power supply 15 60 MHz, 18 mW / cm ³
Positive bias voltage to electrode 13 Nucleation 1 kV
Silicon dot growth 100V
Source gas SiH ₄ gas and hydrogen gas (SiH ₄ 10%)
Silicon dot formation pressure 0.5 Pa to 2 Pa
Plasma extinction period T 500μsec
Plasma lighting period Tc 500μsec
Start positive bias application Ta 100μsec
Positive bias application period Tb 100 μsec
2) Substrate Silicon wafer 3) Substrate temperature 300 ° C
<Evaluation of silicon dots>
When the crystallinity [crystalline / (crystalline + amorphous)] of the silicon dots was measured by analysis by laser Raman spectroscopy, high-quality silicon dots having a crystallinity of 95% or more were confirmed.

(4-2) 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 '500μsec
Plasma lighting period Tc '500μsec
Application of negative ion extraction voltage
Application start Ta ′ 100 μsec
Application period Tb ′ 100 μsec
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 crystallinity of 96% or more were confirmed.

(4-3) 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.

Claims

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. Forming nuclei for silicon dot growth on the silicon dot formation target substrate;
Subsequent to the nucleation, a second positive pulse voltage is applied to the substrate installation electrode to irradiate the silicon dot formation target substrate with negative ions containing silicon in the plasma with the second ion energy. A silicon dot forming method comprising growing silicon dots on the silicon dot formation target substrate based on the nucleus.
In irradiation of negative ions containing silicon to the silicon dot formation target substrate, the first ion energy is set to P [eV] or more when the plasma potential of the plasma is P [V], and the second ion The silicon dot forming method according to claim 1, wherein the energy is 2 keV or less.
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 having a base electrode is formed, plasma is generated from the silicon-containing gas in the first plasma chamber, and a part of electrons in the plasma generated in the first plasma chamber by the electron trapping magnetic field is generated. Silicon contained in the second plasma chamber is contained by the action of electrons having a lower energy than the electrons that are suppressed from moving to the second plasma chamber and suppressed to move to the second plasma chamber. 3. The silicon dot forming method according to claim 1, wherein the concentration of negative ions is increased.
The plasma generation chamber is preliminarily provided with a conductive target on which at least one material selected from cesium, rubidium, potassium and barium is deposited, and plasma generation from the silicon-containing gas by the plasma generation apparatus in the plasma generation chamber 3. The method according to claim 1, wherein a negative voltage is applied to the conductive target in order to bring positive ions in the plasma into contact with the target, thereby increasing the concentration of negative ions including silicon in the plasma. The silicon dot formation method of description.
The conductive target on which at least one material selected from the cesium, rubidium, potassium, and barium is deposited is provided in the plasma generation chamber with the conductive target before the material deposition, and the conductive target before the material deposition is provided on the conductive target. 5. The method of forming a silicon dot according to claim 4, which is obtained by introducing vapor of at least one substance selected from cesium, rubidium, potassium and barium and depositing the substance.
The plasma generator is periodically turned on and off, and the application of a positive pulse voltage to the substrate installation electrode is performed after a predetermined period of time has elapsed from when the plasma generator is turned off until the plasma generator is turned on again. The silicon dot forming method according to any one of claims 1 to 5, wherein the silicon dot forming method is performed during the period.
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. Applying a first positive pulse voltage to form a nucleus to become, and irradiating the silicon dot formation target substrate with negative ions containing silicon in the plasma with a second ion energy, based on the nucleus A silicon dot forming device which is a power supply device for applying a second positive pulse voltage for growing silicon dots.
In irradiation of negative ions containing silicon to the silicon dot formation target substrate, the first ion energy is equal to or higher than P [eV] when the plasma potential of the plasma is P [V]. The silicon dot forming apparatus according to claim 7, wherein the ion energy is 2 keV or less.
A magnetic field forming device for forming an electron trapping magnetic field is provided in an intermediate part 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 having the plasma generating device. And the other side is a second plasma chamber having the base electrode, and plasma is generated from the silicon-containing gas in the first plasma chamber by the plasma generator, and the electron trap formed by the magnetic field generator The movement of some of the electrons in the plasma generated in the first plasma chamber by the 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 can be increased by the action of electrons having lower energy than the electrons. Silicon dot forming apparatus.
A conductive target in which at least one material selected from cesium, rubidium, potassium, and barium is deposited is provided in advance in the plasma generation chamber, and the silicon generation gas from the plasma generation apparatus in the plasma generation chamber is provided. 9. The silicon dot forming apparatus according to claim 7, further comprising a negative bias power supply device that applies a negative voltage to the conductive target during plasma generation.
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;
And 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. The silicon dot forming apparatus according to claim 7 or 8, wherein
The plasma generator is periodically turned on and off, and the application of a positive pulse voltage to the substrate installation electrode by the positive bias power supply device is performed after a predetermined period has elapsed since the plasma generator was turned off. 12. The silicon according to claim 7, further comprising a control unit that controls the plasma generation device and the positive bias power supply device so as to be performed during a period until the device is turned on again. Dot forming device.
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. Introducing and generating plasma from the gas by the plasma generator,
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.
In the irradiation of the silicon dot formation target substrate with negative ions including silicon, the first ion energy is set to P [eV] or more when the plasma potential of the plasma is P [V]. The silicon dot forming method according to claim 13, wherein the ion energy is 2 keV or less.
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 15. The method for forming a silicon dot according to claim 13, wherein the concentration of negative ions containing silicon is increased.
The plasma generation chamber is preliminarily provided with a conductive target on which at least one material selected from cesium, rubidium, potassium and barium is deposited, and plasma generation from the silicon-containing gas by the plasma generation apparatus in the plasma generation chamber 15. The concentration of negative ions including silicon in the plasma is increased by applying a negative voltage to the conductive target and bringing positive ions in the plasma into contact with the target. The silicon dot formation method of description.
The conductive target on which at least one material selected from the cesium, rubidium, potassium, and barium is deposited is provided in the plasma generation chamber with the conductive target before the material deposition, and the conductive target before the material deposition is provided on the conductive target. 17. The method of forming a silicon dot according to claim 16, which is obtained by guiding vapor of at least one substance selected from cesium, rubidium, potassium and barium to deposit the substance.
The plasma generator is periodically turned on and off, and voltage application for negative ion extraction including the silicon to the negative ion extraction electrode device is performed after a predetermined period has elapsed since the plasma generation device was turned off. 18. The method for forming silicon dots according to claim 13, which is performed during a period until the generation device is turned on again.
A plasma generation chamber equipped with a plasma generation device;
A silicon dot forming chamber which 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. Application of a first negative ion extraction voltage to form nuclei that cause silicon dot growth by irradiation with negative ions containing silicon in the plasma to the silicon dot formation target substrate. A silicon dot forming apparatus, which is a power supply device for applying a second negative ion extraction voltage for growing silicon dots based on the nuclei by irradiation with the nuclei.
In the irradiation of the silicon dot formation target substrate with negative ions including silicon, the first ion energy is equal to or higher than P [eV] when the plasma potential of the plasma is P [V]. 21. The silicon dot forming apparatus according to claim 19, wherein the ion energy of is not more than 2 keV.
A magnetic field forming device for forming an electron trapping magnetic field is provided 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 having the plasma generating device. In addition, the other side is a second plasma chamber having the negative ion extraction electrode device, and plasma is generated from the gas containing silicon in the first plasma chamber by the plasma generation device, and electrons are formed by the magnetic field forming device. 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. 20. The concentration of negative ions containing silicon in the second plasma chamber can be increased by the action of electrons having lower energy than the generated electrons. Silicon dot forming apparatus of paragraph 20, wherein.
A conductive target in which at least one material selected from cesium, rubidium, potassium, and barium is deposited is provided in advance in the plasma generation chamber, and the silicon generation gas from the plasma generation apparatus in the plasma generation chamber is provided. 21. The silicon dot forming apparatus according to claim 19 or 20, further comprising a negative bias power supply device that applies a negative voltage to the conductive target in generating plasma.
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;
And 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. 21. The silicon dot forming device according to item 19 or 20 above.
The plasma generator is periodically turned on and off, and the application of a negative ion extraction voltage including silicon to the negative ion extraction electrode device by the negative ion extraction power supply device is a predetermined period after the plasma generation device is turned off. 20. A control unit that controls the plasma generation device and the negative ion extraction power supply device so as to be performed during a period from when the plasma generation device is turned on again after the elapse of time. 24. The silicon dot forming apparatus according to any one of items 23.
A plasma generation chamber provided with a low-plasma-potential plasma generation device and having a substrate installation portion for installing a silicon dot formation target substrate therein and an ion beam irradiated to the silicon dot formation target substrate installed in the substrate installation portion Preparing an ion beam irradiation device to perform,
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. Letting
Exposing the silicon dot formation target substrate placed in the base placement portion to the plasma and irradiating the silicon dot formation target substrate from the ion beam irradiation apparatus to the silicon dot formation target,
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. A silicon dot forming method for forming silicon dots on the silicon dot formation target substrate by performing ion beam irradiation with second ion energy for growth.
In the ion beam irradiation, the first ion energy when the silicon dot formation target substrate is irradiated with the ion beam is set to P [eV] or more when the plasma plasma potential is P [V]. 26. The method of forming a silicon dot according to claim 25, wherein the ion energy of 2 is 2 keV or less.
27. The silicon dot forming method according to claim 25 or 26, wherein ions generated from at least one of an inert gas, a reactive gas, and a gas containing silicon are used as ion species of the ion beam. .
28. The silicon dot forming method according to claim 25, 26 or 27, wherein the plasma potential of the low plasma potential plasma is 50 V or less.
29. The silicon dot forming method according to any one of claims 25 to 28, wherein a plasma density of the low plasma potential plasma is set to 1 × 10 11 ions / cm 3 or more.
The ratio of the number of ions that reach the substrate from the ion beam irradiation apparatus to the number of silicon atoms that reach the silicon dot formation target substrate from the low plasma potential plasma (number of ions / number of silicon atoms) is 0.01-10. 30. The method of forming a silicon dot according to any one of claims 25 to 29.
31. The silicon dot forming method according to claim 25, wherein the low plasma potential plasma generating apparatus is an inductively coupled plasma generating apparatus.