JPH0817576A - Luminescent element and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a display device having a high degree of integration by stacking a silicon dioxide layer on a silicon singlecrystal material, densifying the layer via thermal treatment, then, implanting silicon ions for obtaining a thermally treated luminescent layer. CONSTITUTION:A silicon dioxide film of 300nm thickness is, for example, stacked on the surface of a silicon singlecrystal substrate and thermally treated in nitrogen environment, for example, at 1,000 deg.C for one hour, thereby densifying the film. Silicon ions accelerated up to 1,000keV energy, for example, is implanted to the surface of the oxide film so obtained. Thereafter, another silicon dioxide film of 50nm thickness is again stacked by use of the atmospheric pressure CVD method, so as to maintain the dielectric strength of the oxide film surface. This film, when thermally treated in nitrogen environment, for example, at, 1,050 deg.C for approximately three hours, gives red photoluminescence in the visible ray zone. Finally, the oxide film is removed from the reverse side of the substrate and an aluminum electrode is formed on both sides thereof. Then, the substrate is divided into approximately 5mm square chips. Furthermore, the prescribed AC voltage is applied across both electrodes of the chip element, and electroluminescence is obtained from the edge of the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device. More specifically, the present invention relates to a light emitting element using a semiconductor that can be used as a single light source or can be integrated in a semiconductor integrated circuit.

[0002]

2. Description of the Related Art Conventionally, an EL (Electro Luminescence) which is one of light emitting devices using semiconductors.
e) The element has been limited to the direct transition type compound semiconductor material typified by ZnS. On the other hand, the highly integrated electric circuit for driving the device is the exclusive field of Si. Therefore, attempts have been made to epitaxially grow a compound semiconductor, which is a material of the EL element, on the Si edge crystal in order to integrate the EL element and make it a monolithic structure with a driving circuit thereof, but it has not been achieved yet. Absent.

On the other hand, as another method of making monolithic,
Realization of an EL element using Si as a raw material and having excellent compatibility with a silicon process has been awaited. As a method of constructing such an element, a method of heat-treating an SiO _x film deposited by a CVD method to form Si fine particles in the film has been reported [DJ DiMaria, JRC Cartley, E.J.Pakris, D. W. Don, TS Kuang, F.L.
Pessavent, T. N. Sisys and J. A. Cutro, Journal of Applied Physics, 56, 401, 1984 (DJ
DiMaria, J .; R. Kirtly, E .; J. Pa
kulis, D .; W. Dong, T .; S. Kuan,
F. L. Pesavento, T .; N. Thesis
and J. A. Cutro, J .; Appln. Phy
s. )].

[0004]

[Problems to be Solved by the Invention] However, CVD
The SiO _x film deposited by the method is not always a good film in terms of its density and impurities. Therefore, in reality, the interface characteristics between the Si fine particles themselves formed after the heat treatment and the oxide film surrounding the Si fine particles are inferior, the luminous efficiency is insufficient, and a satisfactory product is not obtained.

An object of the present invention is to provide an EL device which is monolithic with a driving circuit. Specifically, an EL element adapted to a silicon process for forming a drive circuit on a Si substrate and capable of being formed on the same substrate as an integrated circuit including a semiconductor element such as a transistor, specifically, a good EL element made of Si as a raw material. To provide.

[0006]

The light emitting device of the present invention is characterized in that an oxide film into which ions are ion-implanted forms at least a part of the light emitting layer.

In the present invention, by implanting ions capable of becoming a semiconductor material into the oxide film by ion implantation capable of controlling the amount of impurities with sufficient accuracy in the semiconductor process, the amount and size of the semiconductor fine particles are precisely adjusted to the cone. It is possible to form a trawled light emitting layer. As a result, for example, a good light emitting element made of Si as a raw material is formed.

The light emitting device of the present invention can be a light emitting device using a SiO _x film, which has been conventionally demanded, and can be further formed and integrated on the same silicon substrate as the drive circuit.

The present invention will be described in detail below.

FIG. 1 is a sectional view showing a first embodiment of the light emitting device of the present invention. This embodiment is an AC drive type EL element. The light emitting layer 1 formed by the method described below is
It is sandwiched by the insulating layers 2 and 2 ′, and the outside thereof is further sandwiched by the electrodes 3 and 3 ′ made of a conductive material. 2 here
The insulating layer and the electrode, which are present at each location, do not have to be made of the same material.

Further, the interface between the light emitting layer 1 and the insulating layers 2 and 2'need not necessarily be steep, and if the insulation resistance against the driving voltage of the insulating layer is maintained, it continuously changes. Is also good.

The electrode 3 of the light emitting device constructed as described above,
When an AC voltage is applied between 3 ', the semiconductor fine particles contained in the light emitting layer 1 emit light. When the emitted light is taken out vertically to each layer of the light emitting device, at least one of the insulating layer and the electrode must be transparent or semitransparent to the emitted light.

FIG. 2 is a sectional view showing a DC drive type EL device which is a second embodiment of the light emitting device of the present invention. In this embodiment, the light emitting layer 1 is directly sandwiched between the electrodes 3 and 3 ', and unlike the first embodiment, the light emitting layer 1 needs to have a low resistance to the extent that a current can be injected from the outside. When a DC voltage is applied between the electrodes 3 and 3 ′ of the light emitting element thus configured, the semiconductor fine particles contained in the light emitting layer 1 emit light.

FIG. 3 is a sectional view showing a manufacturing process of the light emitting device of the present invention.

First, the oxide film 32 is formed on the conductive substrate 31.
Are formed (FIG. 3A). This base 31 will later function as one of the electrodes of the light emitting element. For example, if the base 31 is a Si substrate, a good oxide film can be obtained by oxidizing the oxide film 32. It is also possible to deposit an SiO ₂ film and perform sufficient heat treatment in advance to improve the film quality and use it. The light emitting device of the present invention can be suitably applied even if it is a material other than Si for the purpose of forming a good EL device.

In the present invention, the thickness of the oxide film is generally 10 nm to 10 in consideration of luminous efficiency and effective electric field.
The range is preferably 0 μm, preferably 100 nm.
It is preferable that the thickness is in the range of 1 μm.

Next, from the surface of the oxide film 32, ions 33 are formed.
Is injected (FIG. 3 (b)). As the ions to be implanted in the present invention, it is desirable to use ions that can be semiconductor materials. Specifically, ions obtained from the elements Si and Ge belonging to Group IV of the periodic table.

Ions obtained from elements capable of forming II-VI group compound semiconductors, that is, Zn, Cd, Hg, Se, Te and Po.

Elements capable of forming III-V group compound semiconductors, that is, Al, Ga, In, Tl, P, As, Sb,
The ion obtained from Bi can be mentioned.

In the present invention, the amount of ions to be implanted varies depending on the ion species to be implanted, but in consideration of luminous efficiency and solid solution limit, it is generally 10 ¹⁰ cm ^-2 to 10 ²² cm.
^-2 is preferable, and preferably 10 ¹⁴ cm ^-2 ~
A range of 10 ²² cm ^-2 is recommended.

At this time, the ion implantation energy must be set so as to obtain an optimum range for the film thickness of the oxide film 32, depending on the form of the light emitting device described below. That is, in the case of the AC drive type EL element shown in FIG. 1, at least the region of the oxide film 32 facing the base 31 needs to be an insulating layer, so that the range is shallower than that. I won't.

On the contrary, in the case of the DC drive type element shown in FIG. 2, it is not preferable to leave the high resistance layer.
It is necessary to inject a deep range that reaches at least the interface. Further, in any case, in order to adjust the distribution of implanted ions in the oxide film 32, it is possible to perform multi-stage ion implantation with different energy and dose.

Next, heat treatment is performed. This is to give a light emitting property by the quantum size effect of the formed semiconductor crystal fine particles by appropriately aggregating the implanted ions. Therefore,
The heat treatment conditions must be adjusted so that fine particles having such a light emitting size are formed. For example, when the heat treatment is insufficient because the temperature is too low or the time is too short, the light emission from the oxide film observed before the heat treatment disappears.

Further, the excessive heat treatment results in that the average size of the crystalline fine particles of the semiconductor fine particles is further increased and the quantum effect is lost, so that the light emitting property is again impaired.

The heat treatment may be, for example, ordinary furnace annealing, or rapid heat treatment (Ra) using an infrared lamp.
Pid Thermal Annealing) or irradiation with an energy beam such as a laser beam, an electron beam, a particle beam or an X-ray.

Next, only in the AC drive type EL element of FIG. 1, if the insulation resistance near the surface of the oxide film 32 is insufficient, an insulating film is formed on this surface. If the range of semiconductor ion implantation is sufficiently deep from the surface, this step is unnecessary. Further, this step may be performed before the heat treatment. As the insulating film, any film such as a silicon oxide film or a silicon nitride film having excellent insulating properties and pressure resistance can be used.

Finally, the upper electrode 3'is formed (see FIG. 3).
(C)). As the material of the electrode, for example, aluminum,
Metals such as gold and tungsten and compounds thereof can be mentioned. When light emission is taken out through this electrode, it is made of a light-transmissive material such as indium tin oxide.

[0028]

【Example】

Example 1 The AC drive type EL device shown in FIG. 1 was produced.

First, a film thickness of 300 n is formed on the surface of a Si single crystal substrate having a specific resistance of 0.01 Ωcm or less by an atmospheric pressure CVD method.
m SiO ₂ film was deposited. 100 in a nitrogen atmosphere
When the film was densified by heat treatment at a temperature of 0 ° C. for about 1 hour, the film thickness was reduced by about 15%.

Si ions accelerated to an energy of 100 keV were implanted into the surface of the oxide film at a dose of 2 × 10 ¹⁶ cm ^-2 . With this energy, the implanted ions hardly reach the interface with the Si substrate.

Next, in order to maintain the insulation resistance of the oxide film surface, a SiO ₂ film having a film thickness of 50 nm was deposited again by the atmospheric pressure CVD method. When heat-treated at a temperature of 1050 ° C. for about 3 hours in a nitrogen atmosphere, this film exhibited red photoluminescence in the visible light region.

Finally, the oxide film on the back surface of the substrate was removed, Al electrodes were formed on both surfaces of the substrate, and the substrate was divided into chips of about 5 mm square. 300 between both electrodes of the device
When an alternating voltage of V and 5 kHz was applied, electroluminescence similar to photoluminescence was observed from the end face of the substrate.

[Embodiment 2] DC drive type E shown in FIG.
An L element was produced. The manufacturing process will be described below.

First, a SiO ₂ film having a film thickness of 100 nm was formed on the surface of a Si single crystal substrate having a specific resistance of 0.01 Ωcm or less by a normal thermal oxidation method. On this surface, Si ions 70
keV, 1 × 10 ¹⁶ cm ^-2 and 30 keV, 2 × 10 ¹⁵ c
Ion implantation was performed once under the condition of m ⁻² . As a result, the distribution of implanted Si becomes almost uniform in the film.

Next, when heat-treated in a nitrogen atmosphere at a temperature of 1100 ° C. for about 1.5 hours, the film exhibited orange photoluminescence in the visible region.

Finally, an ITO film was formed to a thickness of 400 nm, while the oxide film on the back surface of the substrate was removed to form an Al electrode. When a DC voltage of 20 V was applied between both electrodes of the light emitting device thus formed, electroluminescence similar to photoluminescence was observed through the ITO film.

Example 3 An AC drive type EL device was produced.

First, Si having a specific resistance of 0.01 Ωcm or less
On the surface of the single crystal substrate, an S film having a thickness of 350 nm is formed by the atmospheric pressure CVD method.
An iO ₂ film was deposited and heat-treated in a nitrogen atmosphere at 950 ° C. for 1 hour or more. Ge ions accelerated to an energy of 90 keV were implanted on this surface at a dose of 1 × 10 ¹⁶ cm ^-2 , and heat-treated at 900 ° C. for 2 hours in a nitrogen atmosphere. The film showed an orange photoluminescence in the visible region. Was presented.

Finally, the oxide film on the back surface of the substrate was removed to form Al electrodes on both sides of the substrate, and the substrate was divided into chips of about 1 cm square. 200V, 80 between both electrodes of this light emitting device
When an AC voltage of 0 Hz was applied, electroluminescence similar to photoluminescence was observed from the end face of the substrate.

Example 4 A DC drive type EL device was manufactured.

First, on a surface of a Si single crystal substrate having a specific resistance of 0.01 Ωcm or less, S having a film thickness of 80 nm is formed by a normal thermal oxidation method.
An iO ₂ film is formed, and Si ions are applied to the surface of the ke
Implantation was performed under the conditions of V, 2 × 10 ¹⁵ cm ⁻² , and then Ge ions were implanted under the conditions of 25 keV and 1 × 10 ¹⁵ cm ⁻² . When this was heat-treated in a nitrogen atmosphere at 950 ° C. for about 1 hour, this film exhibited yellow-green photoluminescence in the visible region.

Finally, an ITO film was deposited to a film thickness of 300 nm, while an Al electrode was formed on the back surface of the substrate. When a DC voltage of 10 V was applied between these electrodes, electroluminescence similar to photoluminescence was observed from the surface.

Example 5 A DC drive type EL device was manufactured.

On the surface of a Si single crystal substrate having a specific resistance of 0.01 Ωcm or less, a SiO film having a film thickness of 110 nm is formed by an ordinary thermal oxidation method.
₂ films are formed, and Ga ions are applied to this surface at 50 keV, 1
Implantation was performed under the condition of × 10 ¹⁵ cm ^-2 , and then As ions were implanted under the conditions of 30 keV and 5 × 10 ¹⁵ cm ^-2 . When this was heat-treated in a nitrogen atmosphere at 800 ° C. for about 1 hour, this film exhibited green photoluminescence in the visible region.

Finally, an ITO film was deposited to a film thickness of 350 nm, while an Al electrode was formed on the back surface of the substrate. When a DC voltage of 5 V was applied between these electrodes, electroluminescence similar to photoluminescence was observed from the surface.

[Embodiment 6] SOI (Silicon o
(n Insulator) substrate was used to fabricate an active matrix type display device in which a plurality of EL elements and their driving circuits were formed on the same substrate.

FIG. 4 shows a circuit diagram for one pixel. 41 in the figure
Is a pixel selection line, 42 is a data line, 43 is a low voltage access transistor, which is a P-type or N-type field effect transistor, and 44 is an N-type double diffusion field effect transistor for driving high voltage. . The low-voltage / high-voltage transistor is connected to the pixel selection line and the data line for each element. The gate electrode of the low-voltage transistor 43 is the pixel selection line 41, the source is the data line 42, and the drain is the high voltage. The gate electrode of the transistor 44, the source of the high voltage transistor 44 are connected to the data line 42, and the drain thereof is connected to one electrode of the EL element 45 of the present invention.

In this embodiment, when the selection signal is applied through the pixel selection line 41 and the gate electrode of the low voltage transistor 43 is turned on, the selection signal (high voltage, <200V) applied to the data line 42 is high voltage. It is transmitted to the gate electrode of the transistor 44 and turns on the gate electrode. As a result, the selection signal applied to the data line 42 is transmitted to the electrode of the EL element 45 through the high voltage transistor 44, and the light emitting layer of the element emits light.

FIG. 5 shows the high voltage transistor 44 and EL.
A sectional view of an element 45 portion is shown. In the figure, 51 is a Si single crystal substrate, 52 is a SiO ₂ layer, 53 is a drift region, 54 is a drain, 55 is a source, 56 is a field oxide film (thickness 8000 Å) for high breakdown voltage shielding, and 57 is a gate electrode. Is. Although a DC drive type EL element is shown in this figure, the present invention is not limited to this, and an AC drive type EL element having upper and lower insulating layers is also preferably configured. The upper electrode 3'in FIG. 5 is made of a transparent material.

With the above-mentioned structure, it is possible to form a high-density EL pixel with a reduced number of wirings and drive it at a high voltage.

A color active matrix image display device can be constructed by further adding a color filter to this embodiment.

[0052]

As described above, in the present invention, by using the light emitting layer formed by ion-implanting a high quality oxide film, a light emitting element having high light emitting efficiency and good compatibility with Si process can be obtained. It was realized. As a result, the light emitting device can be formed on the same substrate as the Si-based semiconductor electronic device and circuit,
A highly integrated display device can be formed.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a light emitting device of the present invention.

FIG. 2 is a schematic view showing an example of a light emitting device of the present invention.

FIG. 3 is a schematic view showing an example of a manufacturing process of a light emitting device of the present invention.

FIG. 4 is a circuit diagram of an example in which the light emitting device of the present invention is applied to an image display device.

5 is a partial cross-sectional view of the image display device shown in FIG.

[Explanation of symbols]

1 Light Emitting Layer 2, 2'Insulating Layer 3, 3'Electrode 31 Conductive Substrate 32 Oxide Film 33 Ion 41 Pixel Select Line 42 Data Line 43 Low Voltage Transistor 44 High Voltage Transistor 45 EL Element 51 Si Single Crystal Substrate 52 SiO ₂ Layer 53 drift region 54 drain 55 source 56 field oxide film 57 gate electrode

Claims (18)

[Claims] 1. A light emitting device, wherein a film formed by ion-implanting ions capable of becoming a semiconductor material into an oxide film forms at least a part of a light emitting layer. 2. The thickness of the oxide film is 10 nm to 100
The light emitting device according to claim 1, which is in the range of μm. 3. The film thickness of the oxide film is 100 nm to 1 μm.
The light emitting device according to claim 2, which is in the range of m. 4. The light emitting device according to claim 1, wherein the ions are obtained from one of the elements Si and Ge. 5. The ions are elements Zn, Cd, Hg, and S.
The light emitting device according to claim 1, which is obtained from any one of e, Te and Po. 6. The ions are elements Al, Ga, In, T
The light emitting device according to claim 1, which is obtained from any one of 1, P, As, Sb and Bi. 7. The light emitting device according to claim 1, wherein the light emitting layer is sandwiched between electrodes with an insulating layer interposed therebetween. 8. The light emitting device according to claim 1, wherein the light emitting layer is directly sandwiched between electrodes. 9. The light emitting device according to claim 1, wherein the light emitting layer is formed on a substrate, and light emission is controlled by a driving circuit formed on the substrate. 10. A method for manufacturing a light-emitting element, which comprises ion-implanting ions capable of becoming a semiconductor material into an oxide film to form at least a part of a light-emitting layer. 11. The method for manufacturing a light emitting device according to claim 10, wherein heat treatment is performed after the ion implantation. 12. The film thickness of the oxide film is 10 nm to 10 nm.
The method for manufacturing a light emitting device according to claim 10, wherein the light emitting device has a thickness in the range of 0 μm. 13. The oxide film having a thickness of 100 nm to 1
The method for manufacturing a light emitting device according to claim 12, wherein the light emitting device has a thickness in the range of μm. 14. The method for manufacturing a light emitting device according to claim 10, wherein the ions are obtained from one of the elements Si and Ge. 15. The ions are elements Zn, Cd, Hg,
The method for manufacturing a light emitting device according to claim 10, wherein the light emitting device is obtained from any one of Se, Te and Po. 16. The ions are elements Al, Ga, In,
The method for manufacturing a light emitting device according to claim 10, wherein the light emitting device is obtained from any one of Tl, P, As, Sb and Bi. 17. The ion implantation is performed at 10 ¹⁰ cm ^{-2 -1.}
The method for manufacturing a light emitting device according to claim 10, wherein the implantation amount is in the range of 0 ²² cm ^-2 . 18. The ion implantation is performed at 10 ¹⁴ cm ^{-2 -1.}
The method for manufacturing a light emitting device according to claim 17, wherein the implantation amount is in the range of 0 ²² cm ^-2 .