JPH10107314A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device for an infrared light emitting light emitting diode which can be easily manufactured, is mechanically stable, and can manufacture a light emitting diode having a high luminous intensity. . SOLUTION: A semiconductor device of a light emitting diode which generates infrared light has two GaAlAs layers, and a first GaAlAsP type layer 3.2 and an n type layer 3.1, which are amphoteric doped with silicon, are made of aluminum. The content increases exponentially from the surface side of the p-type partial layer to the first layer thickness, and is about 0 atomic% at the surface side of the p-type layer, and the pn junction 3.3
5 to 10 atomic% in the area of
0 at%, a second n-type G layer provided on the surface side of the n-type layer of the first GaAlAs layer and doped with tellurium.
The aluminum content of the aAlAs layer 2 is lower than that of the first GaAs.
It increases exponentially from the interface to the 1As layer to the second layer and is about 6-16 atomic% at the interface to the first GaAlAs layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a window layer for improving light emission, particularly for a light emitting diode which emits infrared light, and a method for manufacturing such a semiconductor device.

[0002]

2. Description of the Related Art EP-A-0356037 describes a method for producing a light-emitting diode having a double heterostructure. On a GaAs substrate, the following layers are formed of GaAlAs with different aluminum contents by sequentially different melts in the order shown.
That is, first, a p-type dispersion layer having an aluminum content of 40 to 90 atomic% is formed. This p-type current distribution layer uniformly distributes current from the surface contact to the active layer. Then 6
A p-type jacket layer having an aluminum content of 0 to 90 atomic% is formed. This is followed by a p-type active layer with an aluminum content of 35-45 atomic%. This p-type active layer forms a first heterojunction with the p-type jacket layer. On the p-type active layer, an n-type jacket layer having an aluminum content of 60 to 90 atomic% is grown. The p-type active layer forms a second heterojunction with the n-type jacket layer. Finally, an n-type transparent carrier layer is formed on the interface covering layer and the first substrate is removed. The n-type transparent carrier layer is made as thick as possible to provide sufficient mechanical stability for the subsequent method steps when individualizing and assembling the diode chip in the case. The light emitting diode manufactured from this semiconductor device is:
Has high luminosity. However, the manufacturing method is very expensive and therefore expensive.

[0003] Gillessen und Schai
rr "Light-Emitting Diode
s ", Prentice Hall Internet
ionical, 1987, Seiten 118-125.
Describes a diode having a so-called graded band gap structure and generating infrared light. G
Ga doped with silicon on aAs substrate
An AlAs layer is grown by liquid phase epitaxy. The composition and geometry of the melt are chosen such that the aluminum content of the layer to be grown decreases continuously in the growth direction along the thickness. Since the silicon contained in the melt is incorporated into the lattice as an acceptor or a donor depending on the temperature of the melt, the light emitting pn junction of the light emitting diode is 1
Only at the specified temperature during the epitaxy process from only one melt. After removal of the GaAs substrate, a contact layer is formed and structured. Subsequently, the diode chips are individualized.

[0004] Due to the relatively simple structure, such a semiconductor device can be advantageously manufactured. Light emitting diodes having diode chips manufactured from these semiconductor devices have lower luminous intensity than those having a double heterostructure.
It is difficult to provide a contact on one surface side of the semiconductor device due to its high aluminum content.

[0005]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an infrared light emitting light emitting diode which can be easily manufactured, is mechanically stable, and allows the production of light emitting diodes with high luminous intensity. It is to present a semiconductor device and to present a method of manufacturing such a semiconductor device.

[0006]

According to the present invention, there is provided, in accordance with the present invention, a semiconductor device in which a first GaAlAs layer doped amphoteric with silicon comprises a p-type partial layer and an n-type partial layer provided thereon. The aluminum content increases exponentially over the entire thickness of the first layer, starting from the surface side of the p-type partial layer, and increasing at the surface side of the p-type partial layer. About 0 at%, about 5 to 10 at% in the area of the pn junction, 25 to 40 at the surface side of the n-type partial layer
Atomic%, and the second n-type GaAlAs layer provided on the surface side of the n-type partial layer of the first GaAlAs layer and doped with tellurium has an aluminum content of the first GaAs.
Starting at the interface to the As layer, it increases exponentially continuously over the entire thickness of the second layer and the first Ga
About 6 to 16 atomic% at the interface to the AlAs layer, but in any case greater than in the area of the pn junction, at least 24 atomic% at the surface, but at most on the surface side of the n-type sublayer be equivalent to. The present invention relates to a method for manufacturing a semiconductor device,
A single-crystal substrate made of GaAs is prepared, and a second epitaxial layer made of n-type GaAlAs is grown from the liquid phase of the first melt, with the second epitaxial layer covering the entire thickness. The aluminum content is continuously exponentially reduced in the growth direction and is at least 24 at.% At the beginning of the epitaxial growth, from the liquid phase of the second melt, a first epitaxial layer of GaAlAs With the aluminum content continuously and exponentially decreasing in the direction of growth over the entire thickness of the first epitaxial layer and at the beginning of the epitaxial growth
The second melt is doped with silicon so that the n-type partial layer grows first, and the p-type partial layer grows later, and these partial layers form a pn junction which emits light. In addition, the substrate is removed by etching. Advantageous refinements of the invention are achieved according to the features of the dependent claims.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a cross section of a light emitting diode chip manufactured from a semiconductor device according to the present invention. The semiconductor device comprises a first Ga doped amphoteric with silicon.
It consists of an AlAs layer 3.2, 3.1. The first GaAlAs layer has a p-type partial layer 3.2 and an n-type partial layer 3.1.
It is divided into and. The surface of the n-type partial layer 3.1 has a second
Is provided, for example, tellurium (Te)
To form an n-type. First GaAl
On the surface side of the As layer and the second GaAlAs layer 2, a contact layer 4.5 is provided. The aluminum content of both GaAlAs layers varies continuously and exponentially over the thickness of each layer. The transition of the aluminum content with respect to the layer thickness is shown graphically in FIG. FIG. 2B shows corresponding points on the cross section of the semiconductor device.

The aluminum content in the first GaAlAs layer starts at a value of approximately 0 atomic% as viewed from the back side of the semiconductor device (the surface of the p-type partial layer 3.2), and is approximately 32 atomic% exponentially. % Value. Since this increase continues without discontinuity over the emitting pn junction 3.3, the p-type sublayer 3.2 and the n-type sublayer 3.1 transition continuously with respect to the aluminum content.

At the pn junction 3.3, the aluminum content is about 8 atomic%, which is about 880 n of the light generated.
m wavelength. At the interface to the second GaAlAs layer 2, the aluminum content of the first GaAlAs layer and thus of the n-type sublayer 3.1 is eventually about 32%. At this point, the aluminum content is the second GaAlAs layer 2
Jump to about 13 atomic% of The important thing here is that
Here, more aluminum in the region of the pn junction 3.3 is incorporated into the crystal. In that case, the band spacing is large enough that no significant absorption of the light generated at the pn junction 3.3 takes place and therefore the second GaAlA
The s layer 2 is transparent to this light.

[0010] Even in the second GaAlAs layer 2, the aluminum content increases exponentially continuously toward the surface. At the surface, the aluminum content is about 25 atomic%. In this case, it is important that the aluminum content at the surface be as low as possible so that the second GaAlAs layer can provide a good electrical contact, while the manufacturing method still described below requires certain minimums at this point. Requires aluminum content. The above 25 atomic% has proven to be particularly advantageous. P of the first GaAlAs layer
The surface of the profile layer 3.2 is provided with a rear contact 4 over the entire surface in the diode chip according to FIG. Since the aluminum content in this layer is smaller than in the pn junction 3.3, this layer is not transparent to the light generated therein. Accordingly, the light is absorbed and does not reach the back contact 4. On the surface of the second GaAlAs layer 2, a structured front contact 5 is provided, as shown in FIG.

[0011] Such an infrared diode has a capacity of about 1.5.
A pulsed operation at a pulse current of A emits a radiation power of about 300 mW at a radiation wavelength of about 870 nm and a flow voltage of about 2.8 V. The diode is thereby particularly suitable for remote control purposes, photoelectric barriers, optical couplers and data transmission, since it can be operated from a 3 V battery consisting of two cells.

The above-described semiconductor device is manufactured by a liquid phase epitaxy method. First, a second GaAlAs layer is grown from a first melt on a surface of a substrate 1 made of GaAs. The composition and geometry of the melt and the temperature profile during growth are chosen such that the aluminum content along the thickness of the grown layer changes as shown in FIG. At the beginning of the growth, the aluminum content of the layer grown instantaneously is about 25 atomic%. At the end of the growth, the aluminum content in the melt drops rapidly, so that the aluminum content drops to about 13 atomic%. The melt additionally contains a doping substance which renders the layer n-type. For this reason tellurium (Te) has proven to be particularly advantageous.

Then, on the surface of the second GaAlAs layer 2, the first GaAlAs layers 3.1, 3..
2 is allowed to grow. The second melt contains silicon as a doping substance. Silicon is GaAlAs
It has the first-mentioned property that it is incorporated as a donor or an acceptor depending on the temperature at which the layer is grown. Therefore, from the melt, pn is determined only by the change of the growth temperature.
A joint 3.3 can be formed. First GaAlA
Also during the growth of the s-layers 3.1 and 3.2, the composition and shape of the melt so that the aluminum content along the growth direction during the growth changes according to the transition shown in FIG. The dimensions are chosen. During the growth of a layer about 150 μm thick, the aluminum content decreases from about 32 atomic% to almost 0 atomic%. At the pn junction 3.3, the aluminum content is about 8 at.%, the n-type sublayer 3.1 having a thickness of about 30 μm being grown before. Due to the low aluminum content, the p-type sublayer 3.2 is not transparent to the light generated at the pn junction 3.3.

Both GaAlAs layers 2 and 3.1, 3..
After 2 is grown, the substrate is removed. Therefore, a mixture of NH ₄ OH and H ₂ O ₂ is suitable as an etching agent. The interface of the second GaAlAs layer 2 towards the substrate has an aluminum content of 24 at this interface.
If it is larger than atomic%, it acts as a limit in etching. At this time, the action of the etching agent forms an oxide that is insoluble in the etching agent, thereby preventing further erosion of the etching agent.

Finally, on the surface of the first GaAlAs layer 3.2 corresponding to the back side of the diode chip to be manufactured later, a back side contact 4 covering the whole surface is provided. n-type second
The surface of the GaAlAs layer 2 is provided with a structured contact 4 as shown in FIG. Subsequently, the semiconductor device is subdivided into diode chips, which are finally assembled into the case.

The method is distinguished by its simplicity and allows the production of high-luminance diodes at relatively low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a light emitting diode chip manufactured from a semiconductor device according to the present invention.

2A is a graph showing a change in the aluminum content of a semiconductor device with respect to a layer thickness, and FIG. 2B is a cross-sectional view of the semiconductor device.

FIG. 3 is a plan view of the light emitting diode chip according to FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 substrate 2 n-type second GaAlAs layer 3.1 n-type partial layer of first GaAlAs layer 3.2 p-type partial layer of first GaAlAs layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Joschen Gerner Vieslotscho am Römerbützer 22 Germany (72) Inventor Klaus Giletssen Heilbronn Firch Germany Germany 10 (72) Inventor Albert Marshallal Germany Flein Traubenssi Utrath 2/1

Claims (15)

[Claims] 1. A first GaAlAs layer (3.2, 3.1), which is amphoteric doped with silicon, comprises a p-type partial layer (3.2) and an n-type partial layer (3.
1) wherein the aluminum content continuously and exponentially increases from the surface side of the p-type partial layer over the entire thickness of the first layer, and the p-type partial layer (3.2 ) At the surface side, about 5-10 at the area of the pn junction (3.3)
Atomic%, 25 to 40 atomic% on the surface side of the n-type partial layer, the second n being provided on the surface side of the n-type partial layer (3.1) of the first GaAlAs layer and being doped with tellurium. Ga
The aluminum content of the AlAs layer (2) is lower than the first Ga
Starting at the interface to the AlAs layer (3.1, 3.2), it increases continuously and exponentially over the thickness of the entire second layer, approximately 6 at the interface to the first GaAlAs layer. １６16 atomic%, except that in any case p
semiconductor, characterized in that it is larger in the area of the n-junction (3.3), at least 24 at.% at the surface, but at most equal to the aluminum content on the surface side of the n-type partial layer (3.1) apparatus. 2. The thickness of the p-type partial layer (3.2) is about 100
140 μm, the thickness of the n-type partial layer (3.1) is about 20 to
The semiconductor device according to claim 1, wherein the thickness is 40 μm. 3. The thickness of the second GaAlAs layer (2) is 4
The thickness is 0 to 60 μm.
3. The semiconductor device according to claim 1. 4. An aluminum content in the area of the pn junction (3.3) of about 8 atomic%,
The semiconductor device according to claim 1. 5. The method according to claim 1, wherein the back side of the p-type partial layer of the first GaAlAs layer is provided with a contact extending over the entire surface. 13. The semiconductor device according to claim 1. 6. The method according to claim 1, wherein a structured front contact is provided on the surface of the second n-type GaAlAs layer. Semiconductor device. 7. A single crystal substrate (1) made of GaAs is prepared, and a second phase made of n-type GaAlAs is formed from a liquid phase of a first melt.
Is grown, the aluminum content being continuously and exponentially reduced in the growth direction over the entire thickness of the second epitaxial layer, and the beginning of the epitaxial growth. A first epitaxial layer (3.2, 3.1) of GaAlAs is grown from the liquid phase of the second melt, with the thickness of the entire first epitaxial layer being Over time, the aluminum content is reduced continuously and exponentially in the growth direction, and at the beginning of the epitaxial growth, 25 to 40 at.
And doping the second melt with silicon,
The p-type partial layer (3.1) grows and, with delay, the p-type partial layer (3.1.
2) A method for manufacturing a semiconductor device, comprising: growing and forming a pn junction (3.3) in which these partial layers emit light; and removing the substrate (1) by etching. 8. The method according to claim 7, wherein the aluminum content in the area of the pn junction is about 5 to 10 atomic%. 9. An aluminum content at the beginning of the epitaxial growth of the second epitaxial layer (2), at most at the beginning of the epitaxial growth of the first epitaxial layer (3.1, 3.2). 9. The method according to claim 7, wherein the content is equal to the aluminum content. 10. The method according to claim 1, wherein the growth of the second epitaxial layer is terminated at about 6 to 16 at.% But in any case with a higher aluminum content in the area of the pn junction. 10. The method according to claim 7, wherein
The method described in one. 11. The method according to claim 7, wherein the first melt contains tellurium as a doping substance.
0. The method according to one of the preceding claims. 12. The first epitaxial layer (3.2,
12. The method according to claim 7, wherein the epitaxial growth according to 3.1) is carried out to a total thickness of about 150 [mu] m, the n-type partial layer (3.1) having a thickness of about 30 [mu] m.
The method described in one. 13. The first epitaxial layer (3.2,
The aluminum content of 3.1) is reduced to almost 0 at the end of the growth.
13. Method according to one of claims 7 to 12, characterized in that it is reduced to atomic%. 14. The method as claimed in claim 7, wherein the substrate is removed by means of an etching solution comprising NH ₄ OH and H ₂ O ₂ . 15. The aluminum content of the second epitaxial layer (2) at the interface with the substrate (1)
15. The method of claim 14, wherein upon removal of the substrate, the interface is selected to terminate etching erosion.