JPH0376168A - Manufacture of electronic device using diamond - Google Patents

Abstract

PURPOSE:To return graphite component to diamond component by adding impurity to diamond on a board by an ion implanting method, holding it in vacuum, on an inert base or in hydrogen, and emitting a laser light thereto. CONSTITUTION:An intrinsic or B-added diamond layer 2 is formed on a base 1 formed with a silicon nitride 1-2 film on a silicon substrate 1-1, a silicon nitride film 7 is formed thereon, a photoresist 8 is formed, and with it as a mask the film 7 is selectively removed. Further, with it as a mask impurity is added into the diamond by an ion implanting method to selectively form an impurity region 10. The base is disposed on a holder 37 in a chamber 40 of a laser annealing apparatus, and the base 30 is emitted with a laser light from an excimer laser 31 through an optical system 32 via a quartz window 36. The chamber 40 is evacuated to vacuum degree of 1X10<-6>-1X10<-10>Torr. As a result, graphite component unintentionally generated by the ion implantation is returned to the original diamond component, and the added impurity can be activated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing an electronic device by adding impurities to diamond using an ion implantation method and then performing laser annealing.

"Prior Art" Development of electronic devices using diamond has just begun, and there are many applications for transistors and integrated circuits. For now, it will be used as a diode, and attempts are being made to apply it to a blue or green visible light emitting element.

Regarding this light emitting element, red light emission is caused by I[
This has already been achieved more than 10 years ago by using -V group compound semiconductors. However, it is extremely difficult to emit blue and green colors, and it has been completely impossible to emit continuous visible light such as white light using crystalline materials.

Attempts to make light-emitting devices and other electronic devices using diamond have already been demonstrated by the present inventor, for example in Patent Application No. 146930 of 1982 (September 1, 1982).
(filed on the 7th).

However, a method in which impurities are added to a light-emitting element using diamond by ion implantation and then laser annealed has become popular (not shown).

"Conventional Disadvantages" The present invention has been made in order to construct an electronic device using diamond, increase its yield, and improve luminous efficiency.

The hole of the present invention was investigated to determine what kind of luminescent center there is in a conventional diamond. Until now, when a large current was applied to a pair of electrodes that make up an element, the grain boundaries (
It was discovered that the drawback was that impurities segregated at grain boundaries (grain boundaries), current was concentrated there, and a large amount of heat was generated, making it impossible to emit sufficient visible light.

Furthermore, no attempt has been made to add impurities to this diamond by precisely controlling the location and temperature.Ion implantation is considered to be particularly effective for this purpose, but this diamond is in a non-equilibrium state. Therefore, it is known that simply implanting ions and subsequently annealing using only heat, like silicon semiconductors, will have no effect. Furthermore, even if the material is heated to 1400''C in a vacuum, this mere heating is annealing in an equilibrium system, so it cannot eliminate the graphite component created by the ion implantation method, nor can it eliminate or reduce lattice defects.

For this reason, it has been considered impossible to locally control valence electrons in diamond in the same way as in silicon semiconductors. That is, in the present invention, the presence of impurities in groups nb, l1rb, IVb, Vb, and VIb of the periodic table of the elements in diamond, particularly impurities of group VIb of the periodic table of the elements, is compared to impurities of groups ■b and Vb of the periodic table of the elements. In addition, it is effective.

There has been a demand for the establishment of an annealing method in a non-equilibrium state or non-equilibrium system in order to replace such impurities into diamond, rather than by ion implantation, or to partially replace them.

Diamond has an optical energy band width of 5 eV, so annealing with a halogen lamp is annealing in a balanced system, and the light energy of the lamp is 1 to 1,5 eV.
Since it is only eV, light passes through it and cannot be used effectively.

Further, thermal annealing in an oxygen-containing atmosphere is impossible because the carbon component of the diamond reacts with oxygen and vaporizes as carbon dioxide gas. Therefore, there has been a need for an annealing method that takes these various conditions into consideration.

OBJECT OF THE INVENTION The present invention is designed to obviate such drawbacks. That is, impurities are added to diamond using an ion implantation method. Further, a laser beam, particularly a laser beam having a wavelength of 1100n to 500ns, preferably a wavelength of 260nm or less (electrically, a light energy of 4.8eV or more) (preferably a pulse width of 11
1 seconds or less>, and the irradiation atmosphere is set to vacuum or 4N.
By performing the process in an inert gas or hydrogen gas of a purity above, the graphite component (having a SPt bond in part or all) generated by ion implantation is returned to a diamond component (having an SP3 bond), and the unpaired bond is Efforts have been made to reduce or eliminate lattice defects caused by the presence of hands.

"Structure of the Invention" In the present invention, impurities are added to the top or inside of a diamond on a substrate or a diamond body using an ion implantation method.

The diamond injected with this impurity is vacuumed (10-'
torr) or in an inert gas or hydrogen with a purity of 4N or higher. The impurity region to which the impurity has been added is then irradiated with a laser beam to reduce or remove lattice defects and to activate the added impurity.

In the present invention, this laser beam is particularly set to 100 to 500 nm,
In addition, laser light is irradiated with pulsed light. The lattice defect area is exposed to light of 4.8 eV or more (light of 260 nm or less)
Even if there is a defect in the diamond, its energy level will be located in the forbidden band, and even if the energy is 5 eV or less and the level is 2.48 eV (500 nm), it will be effectively absorbed in the diamond. We discovered that it is possible to do this and took advantage of this property. The part to be irradiated with the laser beam is heated to a temperature of 700"C or less as auxiliary energy, and the substrate temperature is kept between -196 and 700 degrees during laser irradiation in order to prevent segregation of graphite components, defects, and impurities in the diamond. C, for example, at room temperature.

In the method of the present invention, as impurities added by ion implantation, not only the conventionally known impurities of the IIb group and Vb group, but also the IIb group, IVb group, and VIb group impurities were added.

The diamond to be ion-implanted may be simple diamond, film-like or crystalline diamond formed on a semiconductor such as silicon, or film-like or granular diamond formed on ceramic or silicon nitride.

For example, I-type or P-type diamond is provided, and an impurity doped N (impurity region) is provided in a part of the upper region by ion implantation. At the same time as this impurity region is formed, this region becomes a damaged layer (an amorphous layer and a portion of N where an amorphous or graphite component is generated) due to ion implantation.

For this reason, optical annealing was performed using excimer laser light, which is a non-equilibrium annealing method, to activate impurities, convert graphite components to diamond components, remove defects, and alleviate lattice strain.

As an application of the present invention, a pair of electrodes is provided on the impurity-doped and laser-annealed region and on the undoped diamond. A similar pulsed current or direct current was passed between the plurality of electrodes to provide an electronic device, such as a light emitting device, such as a visible light emitting device.

In the present invention, a second diamond is provided between this upper electrode and the first diamond having an impurity region, and a second diamond is also selectively doped with another type of impurity different from the impurity added to the first diamond. It is effective to add substances by ion implantation, perform laser annealing, and form a junction to form a tri-transistor or other electronic device.

Furthermore, the present invention provides for such a purpose, that is, to more effectively generate ultraviolet light, blue light, and green light.
Group impurities were used as additives. For example, Be (beryllium), Zn (zinc), Cd (cadmium), O (oxygen), S (sulfur), Se (selenium).

An element selected from Te (tellurium) was added by ion implantation. Further, impurities such as carbon belonging to group IVb of the periodic table of elements may be added.

Carbon compounds having C-0H bonds, such as methanol (CH30H) and ethanol (C2H4OH), were used for diamond synthesis.

Another method is to use elements of group IIb of the periodic table of elements, namely B
(boron), AI (aluminum), Ga (gallium)
Or elements of group Vb of the periodic table of elements, such as N (nitrogen), P(
Phosphorus), As (arsenic), and Sb (antimony) may be added after forming the diamond film by ion implantation.

When using the laser annealing method of the present invention, the diamond in which impurity regions have been added is annealed with laser light in vacuum or in an inert gas, with the atmosphere set at, for example, liquid nitrogen temperature to room temperature to 700''C; Furthermore, it is a non-equilibrium type of light energy, and 248 nm using an excimer laser.
KrF laser was mainly used. The pulse width was set to 200 ns or less, and non-equilibrium annealing was performed on the laser-irradiated diamond. In other words, atoms or defects irradiated with light do not recrystallize by moving in a long range order (1 μm or more), but recrystallize in a short range order (0, 1 μm or more).
(1 μm or less), or the atoms did not move, and only the recombination hands were changed from SF3 to SP'' type, or impurities and carbon were sufficiently combined to undergo metamorphosis.

h (157nm), ArF (193nn+)
, KrCl (222 nm), etc. wavelength of 5 to 20 On
A laser with a pulse width of seconds may be used. XeC1 (308nm
), XeF (351 nm), Ar (488
nm) can also be used, but has the disadvantage that the optical energy width is too small. The number of pulses is 1 to 30 PPS (irradiation of 1 to 30 Hals per second), for example, 10 PPS,
At the same time, the substrate was scanned at a speed of 1 to 5 mm/sec.

This is because silicon melts in an equilibrium system when conventionally known silicon semiconductors are ion-implanted, then simply thermally annealed to form a single crystal, and at the same time impurities are activated (converted into donors or acceptors). This is significantly different from an equilibrium system in which recrystallization is performed with movement of elements on a long range order.

The present invention will be described below according to examples.

"Example 1" An embodiment of the electronic device of the present invention is shown in FIG.

FIG. 2 shows an outline of an apparatus for forming diamond in the form of a film for achieving the present invention.

Impurity ions are selectively implanted into diamond formed using a magnetic field microwave CVD device, and the substrate having the impurity region is annealed by a laser annealing device using an excimer laser as shown in FIG. That is,
As shown in Fig. 3, diamond (2) was formed on a substrate (1) having an insulating surface made by forming silicon nitride (1-2) to a thickness of 0.5 μm on a silicon semiconductor (1-1). .

A diamond film was produced using a magnetic field microwave CVD apparatus. Regarding the method of forming a diamond film using this magnetic field microwave CVD apparatus, etc., the apparatus and A method using methane gas is shown.

An outline of forming the diamond of the present invention is shown below.

The substrate (1) having the silicon nitride film (1-2) was immersed in a mixed solution of alcohol mixed with diamond particles, and ultrasonic waves were applied for 1 minute to 1 hour. Then, many minute damages can be formed on the substrate. This damage is 1
, can serve as a source of nuclei for subsequent diamond formation.

This substrate (1) was placed in a magnetic field microwave plasma CVD apparatus (hereinafter also simply referred to as a plasma CVD apparatus). The plasma CVD equipment uses a microwave oscillator (1B) and an attenuator (16) to generate microwave energy at a frequency of 2.45GHz up to 10KW.

It can be added to the reaction chamber (19) through the quartz window (15). Using Helmholtz coils with magnetic fields (17) and (17'), a maximum of 2.2 KG was applied to construct a resonance surface of 875 Gauss. The board inside this coil (
1) was placed in a holder (13) with a substrate presser (14).

The position in the reactor was adjusted using the substrate position moving mechanism (12), and the vacuum was drawn to 10-3 to 10-6 torr. After this, instead of using methane gas, methyl Alcohol (C)I: 108)
Or alcohol such as ethyl alcohol (CJsOH) (
22) was diluted with hydrogen (21) to 40 to 200 volume χ (100 volume % corresponds to Cl30H:Hz=1:1), for example, to 70 volume % and introduced. If necessary, trimethylboron (B(CHi)i) is added as a P-type impurity to the system (2
3) More borate esters (BCOC, Hzn++) such as B(OClli)+ or B(CH3)3/CH3
0H=0.5 to 5χ) was introduced to form a P-type diamond (2) as shown in FIG. 3(A).

The pressure is 0.01 to 3 torr, for example Q, 25 torr
And so.

A magnetic field of 2.2 KG (kilogauss) was applied so that the magnetic field at or near the substrate was 875 gauss. A microwave power of 5 KW was applied, and the temperature of the substrate was set to 200 to 1000°C, for example, 800°C, using the microwave and thermal energy from the substrate holder.

Then, the carbon in the alcohol, which is decomposed by this microwave energy and turned into plasma, grows on the substrate, and diamond (the name "diamond" refers to single crystallized carbon, in which all or most of the sp' bonds are As shown in Figure 3 (A), (2) is 0.5~
5μm For example, average thickness 1.3μII (filming time 2 hours)
was able to achieve growth.

In FIG. 3(A), on a substrate (1) in which silicon nitride (1-2) is formed on a silicon substrate (1-1), intrinsic (no impurity is intentionally added) or B is added. A layer of diamond (2) was formed to an average thickness of 1.3 μm.

Next, as shown in Figure 3(B), these diamonds (2
), a silicon nitride film (7) with a thickness of 0.5 μm is made,
A photoresist (8) was formed to a thickness of 3 μm. Using this photoresist as a mask, the silicon nitride film was selectively removed. Furthermore, this photoresist and silicon nitride film (
Using 7) as a mask, elements of groups Ua, IIb, IIb, IVbSVb, and VIb of the periodic table of elements, such as atoms of group IIb, are added as impurities into the diamond (2) at an accelerating voltage of 20 to 300 KeV by ion implantation. death,
Impurity regions (10) were selectively produced. This impurity had a relatively medium concentration of IX1016 to 5x1019CI11-3.

The photoresist was removed from these.

Note that silicon nitride (7) between the photoresist and the diamond may be formed if necessary, and is not necessarily required.

FIG. 1 shows an outline of the laser annealing apparatus used in the present invention.

Laser annealing was performed using this device.

First, in the drawing, an impurity region (10
) on which the substrate was formed (the whole shown in FIG. 3(B)) was placed on the holder (37) in the chamber (40>).

A heater is provided in the holder. excimer laser (
The laser light from KrF 248 nm) (31) passes through the optical system (32) and is irradiated onto the substrate (30) through the quartz window (36). The laser beam (35) is connected to the optical system scanning device (3
3) in the X direction or Y direction (34). Inside the chamber (40), a turbo molecular pump is used.
It is evacuated to a vacuum level of xlo-'' to IXl0-'' torr.

The energy of excimer laser is 30 to 500 mJ/cm”
Adjusted within the range. The pulse frequency was 0 to 30 PPS. For example, 200a+J and 10PPS. Furthermore, the laser beam was scanned at 1 to 5 a+m/sec. This was advantageous because it did not react with oxygen.

If the underside of this diamond is in direct contact with a silicon substrate, it will easily react with the diamond and the silicon of this substrate. In this example, 17
Since silicon nitride having a melting point of 00''C or less was included, there was no need to worry about alloying diamond and silicon.

Since the wavelength of the laser beam is 248 nn+ (optical energy 5 eV), which is the same as the optical energy width of diamond, light absorption by diamond can be increased. Ion implantation can restore the carbon that has changed from a diamond component to a graphite component. Of course, lattice defects are even smaller, at 2 to 4 eV, so it is necessary to intensively inject energy into such defects and cure-anneal them while obtaining a non-equilibrium state, thereby reducing or removing microscopic defect clusters. I can do it.

The substrate surface was arranged perpendicular to the optical axis (perpendicular in the drawing). However, by making the optical axis of the laser beam and the base surface parallel or oblique so that all of the irradiated light is sufficiently absorbed by the diamond, in other words, all of the laser light is irradiated and absorbed only by the diamond, which can be absorbed by the diamond. This is effective in preventing the temperature rise of a substrate made of a material that does not have a high melting point, that is, a substrate that does not have non-oxide ceramics on the top surface of silicon.

During annealing, the inert substrate is 4N (99°99
% purity or higher) Ole, Ar was used. The temperature of the substrate was -197 to 700'C.

In this way, a junction (referred to simply as a junction since it is not necessarily a PN junction) (FIG. 3 (10-1)) could be created.

In FIG. 3(C), a pair of electrodes (5-1) and (5-2) are placed above the diamond (2) by vacuum evaporation.
It was formed by the spuck method. One of the electrodes was made of titanium (5-1) and was brought into close contact with P-type diamond.

The other layer was a transparent conductive film (5-3), on which a titanium electrode (5-2) was formed in close contact with the impurity region (10) to which impurities were added. Further, wire bonding was applied to each of them, and a protective film of silicon nitride film (6) which also served as an anti-reflection film was formed on the whole.

Then, in FIG. 3(C), the electrical electrode (5-
1) -P-type diamond (2) -Zn, Be+O, S
+Se or Te is added to the diamond (2) by ion implantation and laser annealed to form an impurity region (10)-electrode (5-2) configuration, and a junction (10-
1) can be used to create a structure in which light is generated externally.

In the structure of FIG. 3(C), 5 to 5
30v (DC ~ 100Hz Dewey ratio 1) e.g. 20V
It was applied at a voltage of . If laser annealing is not performed, a voltage as high as 70 to 200 V is required for light emission. However, by performing the laser annealing of the present invention, it has become possible to lower the applied voltage to a practical level and to emit visible light, particularly blue light, from the impurity region. The strength was 18 candela/1112. In addition to adding oxygen to this diamond, impurity regions (
It was effective to add sulfur, selenium, or tellurium to 10) to increase the luminescence intensity.

This embodiment has the advantage that pinholes in the diamond itself do not pose a problem because the current is passed in the lateral direction. However, two types of impurities (B and S, Se
or Te), the doping of ion implantation must be increased, which is not necessarily suitable for mass production.

``Effect'' Until now, even if impurities were added to diamond during film formation using ion implantation, the added impurities were inactive, and the upper part of the bulk carbon was transformed into graphite. In contrast, in the present invention, by performing laser annealing in addition to ion implantation, it is possible to return the graphite component that was inadvertently generated by this ion implantation to the original diamond component, and to activate the added impurities. It became. By keeping the doping amount constant, it has become possible to create electronic devices with extremely high controllability.

The present invention has mainly been described in the case where one light emitting element is manufactured. However, an electronic device is made by integrating multiple diamond transistors, heat-resistant diodes (rectifiers), and these on the same substrate, and after completing this electronic device, it is necessary to scribe and break it to an appropriate size. It is effective to form a single or integrated light emitting device one by one. Furthermore, including such electronic devices, it is not possible to integrate diodes, transistors, resistors, and capacitors using the same diamond and silicon semiconductor above or below to form a composite integrated electronic device. It is valid.

[Brief explanation of drawings]

FIG. 1 shows a laser annealing apparatus used in the present invention. FIG. 2 shows an example of a magnetic field microwave apparatus for forming diamond according to the present invention. FIG. 3 shows an example of a diamond electronic device made by the method of the present invention. 2... Diamond 5-1.5-2... Electrode 10... Impurity region

Claims (1)

[Claims] 1. A step of adding an impurity into the diamond by ion implantation to form an impurity region, and a step of irradiating the impurity region with laser light while the diamond is in a vacuum or in a non-oxidizing atmosphere. 1. A method for manufacturing an electronic device using diamond, characterized in that the electronic device has the following characteristics. 2. An electronic device using diamond as set forth in claim 1, wherein the impurity is comprised of an element from Group IIa, Group IIb, Group IIIb, Group IVb, Group Vb, or Group VIb of the Periodic Table of Elements. How to make