JPH0563234A - Semiconductor device and operating method thereof - Google Patents

Abstract

PURPOSE:To obtain a silicon optical semiconductor device having a light emission function, by forming a light-emitting element in a silicon semiconductor device. CONSTITUTION:On the surface of an n<+>-type silicon region 11, a high resistance region 13 of an i-type, an n<->-type or a p<->-type is provided, and thereon, an n<+>-type silicon region 18 is provided. On the side face of the high resistance region 13, an oxide film 15 is formed, and thereon, a polycrystalline silicon region 17 is formed. On the n<+>-type silicon region 11, a source electrode 21 is formed, and on the n<+>-type silicon region 18, a drain electrode 22 is formed. Also, the polycrystalline silicon region 17 is used as a gate electrode. The drain voltage having a positive polarity against the source electrode 21 is applied to the drain electrode 22, and a control voltage is applied to the gate electrode 17. The electrons in the source region 11 are accelerated toward the drain region 18 by the drain voltage, while being controlled by the gate electrode. near the drain region 18, the electrons, which have sufficiently high energies by accelerating, cause light emissions, and a light is emitted from a light emission window 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device capable of emitting light, and more particularly to a semiconductor device capable of emitting light using silicon.

Silicon has the top of the valence band at the Γ point,
It is an indirect transition type semiconductor having a low part of the conduction band in the vicinity of the point X and is widely used as an electronic functional element and a light receiving element, but it has received little attention as a light emitting element. The semiconductor light emitting device is made of a direct transition type compound semiconductor such as GaAs.

In recent years, research and development of optical semiconductor ICs have been actively conducted, but integration of light-emitting devices and electronic circuits is often done by using a direct transition type compound semiconductor substrate and incorporating electronic circuits together with the light-emitting devices. Is done by.

[0004]

2. Description of the Related Art Conventionally, a semiconductor light emitting device has been formed by using a direct transition type semiconductor having a bandgap energy corresponding to a desired emission wavelength.

For example, AlGaAs or the like is used to obtain red light in the visible region, and Ga is used to obtain near infrared light.
InG is used to obtain 1 μm band infrared light by using As or the like.
aAs etc. were used. These light emitting elements are formed on a GaAs substrate or an InP substrate.

A so-called optoelectronic device, in which a light emitting element and an electronic circuit are integrated on the same semiconductor chip, is mainly used in combination with the above light emitting element such as GaAs or I.
It is formed by integrating electronic circuits formed of nP or the like.

In the electronic circuit using Si, the transistor is miniaturized as the degree of integration is improved. With the progress of miniaturization, hot electrons have become a problem.
An emission phenomenon near 500 nm is observed near the drain of the MOS transistor in association with hot electrons.

[0008]

Although technologies such as integration of Si semiconductor devices have progressed, it has been difficult to integrate light emitting elements.

A semiconductor device using a direct transition type semiconductor capable of forming a light emitting element has not yet been sufficiently developed with respect to a technique such as integration as compared with a Si semiconductor device. Therefore, it is difficult to form a semiconductor device having a sufficiently high degree of integration.

An object of the present invention is to provide a silicon semiconductor device including a light emitting element. Another object of the present invention is to provide an operating method for producing light emission using a silicon semiconductor device.

[0011]

The semiconductor device of the present invention comprises:
A silicon semiconductor region forming a main current path, a carrier supply terminal that mainly supplies charge carriers to the main current path, a carrier collection terminal that mainly extracts charge carriers from the main current path, and a potential in the main current path. It has a control terminal for controlling, and a light emission window for extracting light generated between a position corresponding to the control terminal of the main current path and a position corresponding to the carrier collection terminal to the outside.

A method of operating a semiconductor device according to the present invention is
A predetermined voltage is applied between the carrier supply terminal, the control terminal, and the carrier collection terminal of the semiconductor device to generate a high electric field in the silicon semiconductor region, and the impact of carriers under the control of the control terminal. Ionization is caused to excite electrons into the L ₃ band of the conduction band, and transition is made to the L ₁ band of the conduction band to cause light emission.

[0013]

Even in the silicon semiconductor region, when electrons are excited to a high energy state, light emission occurs in the MOS.
Observed in transistors. It is considered that this emission is due to the direct intra-band transition from the L ₃ band to the L ₁ band in the conduction band of silicon.

By positively exciting charge carriers to a high energy level in the silicon semiconductor region, a direct transition from a high energy level to a low energy level is possible, and light emission can be obtained by the direct transition.

When the impact ionization of carriers is caused, the electrons are excited to a high energy state and L _{3 in} the conduction band is excited.
Can transition to band. The transition from the L ₃ band to the L ₁ band is a direct transition and causes emission in the visible region wavelength.

[0016]

1 shows a silicon semiconductor device according to an embodiment of the present invention. 1A is a perspective view schematically showing the configuration of a silicon semiconductor device, and FIG. 1B is a band diagram showing a band structure of silicon.

In FIG. 1A, n which becomes a source region
I serving as a channel region on the surface of the ⁺ type silicon region 11
Type or n ⁻ type or p ⁻ type high resistance region 13 is arranged, and n ⁺ type silicon region 18 to be a drain region is arranged thereon. An oxide film 1 is formed on the side surface of the high resistance region 13.
5 is formed, and a polycrystalline silicon region 17 electrically separated from the high resistance region 13 is formed thereon.

The n ⁺ -type on the silicon region 11 forms a source electrode 21, n ⁺ -type Si region 18 the drain electrode 2 on
Form 2. Further, the polycrystalline Si region 17 is used as a gate electrode.

A positive drain voltage is applied to the drain electrode 22 with respect to the source electrode 21, and a control voltage is applied to the gate electrode 17. The electrons in the source region 11 are accelerated toward the drain region 18 by the drain voltage while being controlled by the gate electrode. Drain region 18
The electrons accelerated to sufficiently high energy in the vicinity emit light and emit light from the light emission window 10. The light exit window 10 is
It is formed by a plane parallel to the current path and substantially perpendicular to the semiconductor surface.

FIG. 1B shows a band structure of silicon. The top of the valence band exists in the Γ ₂₅ ′ band at the Γ point,
The bottom of the conduction band exists near point X. At point L,
The bottom conduction band is the L ₁ band and the band above it is the L ₃ band.

When an electron is excited in this L ₃ band, L ₃
A direct transition from the ₃ band to the L ₁ band occurs. The energy associated with this direct transition is more than about 2 eV and about 5
It corresponds to light having a wavelength of 00 nm or less. Short channel MOS
Light emission observed near the drain of the transistor is near 500 nm, which is considered to correspond to this L ₃ → L ₁ transition.

That is, in a Si semiconductor device, when a high electric field is applied to the semiconductor region, electrons are brought into a high energy state due to impact ionization and the like, and excited from the ground state X point to the L point L ₃ band. Be done. By promoting this excitation, the transition from the L ₃ band to the L ₁ band can be promoted.

By forming a high electric field of about 10 ⁵ V / cm in the Si region, controllable impact ionization immediately before the occurrence of avalanche breakdown can be generated.
By utilizing such a state, it becomes possible to cause light emission from the semiconductor region of the MOS transistor and to control the amount of light emission.

FIG. 2 shows a more specific embodiment of the present invention. FIG. 2A schematically shows a semiconductor device. An i-type Si high resistance region 13 serving as a channel region is formed on an n ⁺ type Si region 11 serving as a source region, and n is formed thereon.
^{A +} type Si region 18 is arranged and forms a drain region.

A silicon oxide film 15 is formed on the side surface of the channel region 13, and a polycrystalline Si region 17 serving as a gate electrode for controlling the potential of the high resistance region 13 is arranged via the silicon oxide film. .. Polycrystalline Si on the left side of the figure
A gate electrode 23 made of Al is arranged on the region 17.

On the right side of the n ⁺ type Si region 11, an n ⁺ type Si region 19 serving as a source extraction region is formed, and a source electrode 21 made of Al is arranged thereon. Although the silicon oxide film 20 is formed on these regions, the n ⁺ -type S serving as the drain region is formed.
An opening 25 for taking out a drain electrode is formed on the i region 18, and a drain electrode 22 made of Al is arranged thereon.

Both side portions of such a vertical MOS transistor structure are removed by etching to expose parallel semiconductor side surfaces 10. When a high electric field is formed in the vicinity of the n ⁺ type Si region 18 serving as the drain region and carriers are excited to a high energy state to emit light, light is emitted from the side surface 10.

That is, the side surface formed by etching forms the emission window 10. The pair of parallel planes forms a resonator CAB, and laser oscillation can be generated inside the resonator CAB.

A photodetector for detecting the emitted light is arranged so as to face the light emitting surface 10 or the resonator CAB. FIG. 2B is a plan view schematically showing the arrangement of the resonator CAB of the light emitting element and the photodiode PD as the light receiving element. The photodiodes PD1 and PD2 are formed so as to face the light emitting surface 10 of the resonator CAB. The light emitted from the resonator CAB reaches the photodiode PD, which is a light receiving element, through the notch and is detected there.

By integrating a circuit for processing an electric signal detected by the photodiode PD on the same semiconductor substrate, a large-scale optical semiconductor device can be integrated on the Si substrate.

3 and 4 schematically show a manufacturing method for manufacturing the semiconductor device shown in FIG. In FIG. 3A, the oxide film 12 is selectively formed on the n ⁺ type Si substrate 11.
And forming an opening in the oxide film 12, an i-type Si region 13 is epitaxially grown thereon.

As shown in FIG. 3B, the i-type Si region 1 is formed.
After the silicon oxide film 14 is formed on the surface of No. 3, an impurity-doped polycrystalline Si region 17a is deposited on the surface, and a photoresist layer 25 is formed thereon to form a flat surface. The surface of the photoresist layer 25 is etched to a predetermined depth by control etching. When the surface of the i-type Si region 13 is exposed by etching, the etching is stopped.

As shown in FIG. 3C, after etching,
The surface is oxidized to form a thin silicon oxide film 16b on the i-type Si region 13 and a thick silicon oxide film 16a on the polycrystalline Si region 17. Such a silicon oxide film can be formed by one-time oxidation, but after forming a thin silicon oxide film 16b on the i-type Si region 13,
A thick film of silicon oxide 16a is formed on the polycrystalline Si region 17 by forming an anti-oxidizing mask on the polycrystalline Si region 17 by forming an anti-oxidizing mask on the polycrystalline Si region 17 by removing the antioxidant mask on the polycrystalline Si region 17. May be formed.

Next, by performing etching, as shown in FIG.
The surface of the i-type Si region 13 is exposed as shown in FIG. Even when i-type Si region 13 is exposed, silicon oxide film 15 remains on the surface of polycrystalline Si region 17.

After that, an etching mask such as a photoresist is formed on the surface, and selective etching is performed to selectively expose the surface of the n ⁺ type Si substrate 11.
After that, the etching mask is removed. In FIG. 4A, the n ⁺ type Si substrate 1 exposed on the right side portion in the figure
1 is shown.

As shown in FIG. 4B, selective epitaxial growth is performed to grow n ⁺ type Si regions 18 and 19 on the exposed surface of the Si single crystal. The n ⁺ type Si region 18 forms the drain region of the MOS transistor, and the n ⁺ type Si region 19 forms the source extraction region of the MOS transistor.

Thereafter, as shown in FIG. 4C, an oxide film 20 is formed on the surface and patterned to expose the surfaces of the polycrystalline Si region 17 and the n ⁺ type Si region 19, and the Al film
The electrodes 21 and 23 are formed. In this way, the gate electrode and the source electrode are formed.

After that, the oxide film 20 is further patterned, and a drain electrode is formed on the n ⁺ type Si region 18 to form a MOS transistor structure. After that, by performing anisotropic etching, the resonator CAB
A structure is formed and a semiconductor device as shown in FIG. 2 is obtained.

Before forming the Al electrode, anisotropic etching is performed to form a resonator structure, and then an oxide film or the like is deposited in a notch region formed by etching to form a waveguide structure filled with a transparent material. It may be formed and then an Al electrode may be formed. Even if the notches are not entirely filled, a passivation film such as a silicon oxide film is formed on the semiconductor surface.

The light emission generated in the Si region has a wavelength of about 500 nm. It is preferable to embed the resonator with a material that is transparent to this light and passivate the semiconductor surface.

FIG. 5 shows another embodiment of the present invention. In this embodiment, a waveguide formed of an oxide film or the like is formed in contact with the light emitting surface. 5A shows a planar structure, FIG. 5B shows a cross-sectional view taken along the line AA ′ in FIG. 5A, and FIG. 5C shows B- in FIG. 5A.
A sectional view taken along the line B ′ is shown.

In FIG. 5A, the MOS transistor FET1 is formed in the central portion in the same manner as in the above-mentioned embodiment. The portion other than the FET 1 is removed up to the surface of the n ⁺ type Si substrate 11 by anisotropic etching.

As shown in FIGS. 5B and 5C, a thick silicon oxynitride film 31 is formed on the surface of the n ⁺ -type Si substrate 11, and an n ⁻ -type Si region 13 and a drain region to be a channel are formed. Is embedded in the n ⁺ type Si region 18. The silicon oxynitride film 31 is patterned into a planar shape as shown in FIG.

In this way, the optical waveguides WG1 and W formed of the silicon oxynitride film 31 in contact with the light emission window 10 are formed.
G2 is formed. The silicon oxynitride film 31
The surface is preferably covered with a silicon oxide film 32 having a refractive index lower than that of silicon oxynitride. Thus, by covering the high refractive index transparent region 31 with the low refractive index transparent region 32, the light confinement structure is more completely formed. It is also possible to use doped silicon oxide or the like as a transparent material having a different refractive index.

With such a structure, in the structure of FIG. 5A, the emitted light emitted from the side surface of the FET1 can be transmitted to a desired position via the optical waveguides WG1 and WG2. In the configuration shown, the optical waveguide WG1 is branched into two optical waveguides WG3 and WG4.

Beyond the optical waveguides WG1, WG, WG4,
For example, a photodiode for detecting light is arranged. Although the case where the Si light emitting element is formed by using the MOS transistor structure has been described above, the Si light emitting element can be formed by using a transistor structure other than the MOS transistor.

For example, a MOSF is used as a unipolar transistor whose main current is composed of carriers of one polarity.
A junction type FET, MESFET or the like can be used as in the case of ET. Note that SIT is also included in the FET. Also, a bipolar transistor in which the carriers forming the main current are bipolar can be used.

FIG. 6 shows a Si light emitting device using a bipolar transistor according to an embodiment of the present invention. An n ⁺ -type Si region 42, which is a collector extraction region, is arranged on one surface of an n ⁻ -type Si region 41, which is a collector region.
A p-type Si region 43 serving as a base region is arranged on the other surface.

An n ⁺ type Si region 44 to be an emitter region is formed on the surface of the p type Si region 43. n ⁺ type Si
An emitter electrode 48 is formed on the surface of the region 44, a base electrode 49 is formed on the surface of the p-type Si region 43, and a collector electrode 47 is formed on the surface of the n ⁺ -type Si region 42.

At least one side surface of such a bipolar transistor structure is exposed by being etched down substantially perpendicularly to the main surface to form a light emission window 10. A positive voltage is applied to the collector electrode 47 with respect to the emitter electrode 48.
By applying a positive control voltage to the base electrode 49 with respect to the emitter electrode 48, the bipolar transistor structure functions as a normal bipolar transistor.

Collector region 41 (and base region 43)
When the electric field in (part of) becomes stronger than a certain level, impact ionization occurs in this high electric field region, and electrons are excited to the L ₃ band in a high energy state.

[0052] When electrons are excited to L _3-band, cause a transition from L _3-band to L ₁ band, consisting of the light exit window 10 so the light is emitted. In this way, a light emitting device using Si is constructed as in the above-described embodiments. A pair of parallel planes may be formed, and a resonator may be formed between them to perform laser action.

FIG. 7 shows a method of manufacturing a semiconductor device using the bipolar transistor shown in FIG. 6 as a light emitting element. FIG. 7A shows a bipolar transistor structure in which a normal subcollector is embedded.

[0054] The n ⁺ -type region 42 serving as a sub-collector p-type silicon substrate 40 surface is selectively formed, n thereon ^-
N ⁺ type Si region 4 by epitaxially growing type Si
An n ⁻ type Si region 41 in which 2 is embedded is formed. This n
^The- type Si region 41 constitutes a high resistivity collector region. The n ⁻ type Si region 41 is selectively doped with a p type impurity to form a p type Si region 43 serving as a base region.

Further, the p + type Si region 43 is further selectively doped with an n type impurity to serve as an emitter region n ^+.
A type Si region 44 is formed. Also, in other parts,
An n ⁺ type region reaching the n ⁺ type Si region 42 serving as a subcollector from the surface is formed, and a collector extraction region 51 is formed.

After that, selective etching is performed to obtain an n ⁺ type Si region 44, ap type Si region 43, and an n ⁻ type S region.
A trench surrounding the i region 41 and a trench surrounding the collector extraction region 51 are formed, and the trench is backfilled with an insulating isolation region 45 such as silicon oxide.

On the surface of the bipolar transistor structure thus formed, the collector electrode 47, the emitter electrode 48 and the base electrode 49 are selectively formed of polycrystalline silicon or the like. The emitter electrode 48 and the base electrode 49 are separated by the silicon oxide film 46.

After the bipolar transistor is formed in the Si substrate in this manner, etching is performed to reach the n ⁺ type buried region 42 from the semiconductor surface as shown in FIG. 7B, and the side surface of the bipolar transistor structure is exposed. Exposed groove portions 52 and 53 are formed. An optical waveguide can be formed by embedding a transparent medium such as silicon oxide in these grooves 52 and 53.

As described above, in a semiconductor device using Si, electrons are excited to a high energy state, which causes a direct transition from the L ₃ band to the L ₁ band in the conduction band to cause light emission. be able to.

When the light emission thus generated is received by the light receiving element formed in the same substrate, a Si optical semiconductor device including the light emitting element and the light receiving element can be constructed. S
An i-semiconductor device highly integrated technology can be used to provide an optical semiconductor device with a high degree of integration.

The present invention has been described above with reference to the embodiments.
The present invention is not limited to these. For example,
It will be apparent to those skilled in the art that various modifications, improvements, combinations and the like can be made.

[0062]

Since the light emitting element can be formed in the Si semiconductor device, a silicon optical semiconductor device having a light emitting function is provided.

Since the light emitting element, the light receiving element and the electronic circuit can be integrated on the silicon substrate, a highly integrated optical semiconductor device is provided.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. 1A is a perspective view showing a structure of a MOS transistor having a light emitting function, FIG.
(B) is a diagram showing the band structure of Si.

FIG. 2 shows an embodiment of the present invention. FIG. 2A shows a perspective view and FIG. 2B shows a plan view.

FIG. 3 shows a manufacturing method for manufacturing the embodiment shown in FIG.

FIG. 4 shows a manufacturing method for manufacturing the embodiment shown in FIG.

FIG. 5 shows an embodiment of the present invention. 5A shows a planar structure, and FIGS. 5B and 5C show sectional structures.

FIG. 6 shows an embodiment of the present invention.

7 illustrates a manufacturing method for manufacturing the structure of FIG.

[Explanation of symbols]

10 Light Emitting Window 11 n ⁺ Type Si Region 13 High Resistance Region 15 Silicon Oxide Film 17 Polycrystalline Si Region 18 n ⁺ Type Si Region 19 n ⁺ Type Si Region 21 Source Electrode 22 Drain Electrode 23 Gate Electrode CAB Resonator WG Optical Waveguide 47 collector electrode 48 emitter electrode 49 base electrode

Claims (8)

[Claims] 1. A silicon semiconductor region (11, 13, 18) constituting a main current path, a carrier supply terminal (21) for mainly supplying charge carriers to the main current path, and charge carriers mainly from the main current path. Of the carrier collecting terminal (22) for pulling out the electric current, the control terminal (17) for controlling the potential in the main current path, the position corresponding to the control terminal of the main current path, and the position corresponding to the carrier collecting terminal. A semiconductor device having a light exit window (10) through which light generated between the light exits. 2. The silicon semiconductor region includes at least n-type regions at both ends thereof, and the generated light is due to a direct transition from the L ₃ band to the L ₁ band of the conduction band of silicon. Semiconductor device. 3. The semiconductor device is formed in a silicon semiconductor substrate having a main surface, and the light exit window is formed by a surface formed substantially perpendicular to the main surface.
The semiconductor device according to any one of claims 1 to 3. 4. The semiconductor device according to claim 1, wherein the light exit window is formed by a pair of parallel planes, and a resonator is defined between the parallel planes. 5. The semiconductor device according to claim 1, further comprising a waveguide region (WG) which is disposed in contact with the light exit window and is made of a transparent material. 6. The semiconductor device according to claim 1, wherein the silicon semiconductor region forms a channel of a unipolar type transistor. 7. The semiconductor device according to claim 1, wherein the silicon semiconductor region constitutes a base region and a collector region of a bipolar transistor. 8. The semiconductor device according to claim 1, wherein a predetermined voltage is applied between the carrier supply terminal, the control terminal and the carrier collection terminal to generate a high electric field in the silicon semiconductor region, and the control is performed. Under the control of the terminal, impact ionization of carriers is generated to cause electrons to pass through the conduction band L ₃
A method for operating a semiconductor device, which emits light by being excited to a band and transiting to the L ₁ band of a conduction band.