JPH06296035A - Photodetector and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a photodetector, on which optical coupling coefficient and light-receiving sensitivity are improved and a highly efficient semiconductor electronic device is used. CONSTITUTION:In this photodetector consisting of a MESFET 20 formed in such a manner that an electrode becomes both sides of a semiconductor substrate 10, a light-introducing window, which reaches the lower part of the MESFET 20 from both sides of the semiconductor substrate 10, is provided on the part corresponding to the MESFET 20 of the semiconductor substrate 10. As a result, the light impinged upon the MESFET 20 can be made incident from the non-electrode side via the light-introducing window 30, and the light can be impinged efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector which is a constituent element of a high frequency IC used for optical communication, wireless communication and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a photodiode has been generally used as an optical / electrical conversion module, and the photodiode is used as a photodetector, and an optoelectronic integrated circuit integrated with a transistor constituting an electric processing section ( OEIC) has been realized (for example, IEEE J.Light
wave Tech., Vol.8, 846 (1990) M.Dagenaise et al., "
Application and Challenges of OEIC Technology: A Re
port on the 1989 HiltonHean Workshop "). However, it is difficult to integrate high-performance on the same chip because the device design (epitaxial crystal structure, etc.) for high-performance is greatly different between the photodiode and the transistor. Met.

On the other hand, an OEIC which directly uses a semiconductor electronic device such as MESFET or HEMT as a photodetector
According to this configuration, since the photodetector and the electric processing unit can be configured by the same transistor, the integration was easy (for example, IEICE technical research report, MW92.
-56 (1992), Baba et al., "Study of optical detection using microwave / millimeter wave devices").

FIG. 2 shows an example of the above-described conventional photodetector, here a photodetector using an FET, in which a gate electrode 2, a source electrode 3 and a drain electrode 4 are formed on an upper surface 1a of a semiconductor substrate 1, Light is made incident from the upper surface 1a side of the substrate 1. In this configuration, part of the incident light is reflected by the electrodes 2, 3 and 4,
There is a problem that the optical coupling coefficient cannot be increased and the reaction under the gate electrode 2 where the photoelectric effect most efficiently occurs cannot be effectively used.

In the photodetector, the semiconductor electronic device is made wider by widening the gap between the gate electrode 2 and the source electrode 3 and the gap between the gate electrode 2 and the drain electrode 4 so that the light sufficiently strikes the semiconductor substrate 1. As a result, there is a problem that the amplification characteristic deteriorates, and as a result, the light receiving sensitivity also decreases.

As described above, in the conventional photodetector in which light is incident from the upper surface side of the substrate, there is a limit in improving the light receiving sensitivity.

[0007]

In view of the above-mentioned conventional problems, the present invention realizes an OEIC in which a semiconductor electronic device is directly used as a photodetector. Therefore, the optical coupling coefficient is improved and the light receiving sensitivity is improved. An object of the present invention is to provide a photodetector using a high-performance semiconductor electronic device and a manufacturing method thereof.

[0008]

In order to achieve the above object, the present invention provides a photodetector comprising a semiconductor electronic device in which an electrode is formed only on one surface side of a semiconductor substrate. A photodetector having a light introduction window reaching the lower part of the semiconductor electronic device from the other surface side of the semiconductor substrate in a portion corresponding to the electronic device, and the first semiconductor layer on the first semiconductor layer. A step of laminating a second semiconductor layer capable of selectively etching only the first semiconductor layer, a step of manufacturing a semiconductor electronic device on the second semiconductor layer, and a step of forming a portion of the first semiconductor layer corresponding to the semiconductor electronic device. We propose a method for manufacturing a photodetector, which comprises the steps of etching and forming a window for introducing light.

[0009]

According to the device of the present invention, the light to be incident on the semiconductor electronic device can be incident from the surface side without the electrode through the light introducing window, and the light can be effectively incident to the optical coupling. The coefficient and the light receiving sensitivity can be greatly improved. According to the method of the present invention, the second
By providing the semiconductor layer of, it is possible to form a window for introducing light stably with a large process margin in the same process as the via hole, and manufacture a photodetector using a high-performance semiconductor electronic device. can do.

[0010]

1 shows a first embodiment of the photodetector of the present invention, in which MESF is used as a semiconductor electronic device.
An example using ET will be shown. In the figure, 10 is a semiconductor substrate, which is formed by laminating a non-doped GaAs buffer layer 12, a non-doped AlGaAs etching stopper layer 13, and a non-doped GaAs layer 14 for device fabrication on a GaAs substrate 11. 20 is a MESFET,
A buried p layer 21, a channel layer 22, and a semiconductor layer 2 for a source are formed on the non-doped GaAs layer 14 for device fabrication.
3, a semiconductor layer 24 for drain, a gate electrode 25, a source electrode 26 and a drain electrode 27 are formed.
Reference numeral 30 denotes a light introducing window, which is a non-doped GaA portion of the semiconductor substrate 10 corresponding to the MESFET 20.
The s buffer layer 12 is removed.

FIG. 3 shows the manufacturing process of the photodetector of FIG. 1, and the manufacturing method will be described below.

First, a non-doped G is formed on the GaAs substrate 11.
aAs buffer layer 12 of 200 nm, undoped AlGa
As etching stopper layer 13 is 100 nm, non-doped GaAs layer 14 for device fabrication is 5000 nm, MBE and M
The semiconductor substrate 10 is manufactured by sequentially stacking it by OCVD or the like (FIG. 3A). Next, the buried p layer 21 and the channel layer 22 are formed on the semiconductor substrate 10 by ion implantation using the photoresist as a mask (FIG. 3 (b)).

Next, a gate material such as W or Ni is laminated,
The gate electrode 25 is formed by RIE or the like using the photoresist as a mask (FIG. 3 (c)). Next, using the gate electrode 25 as a mask, the source semiconductor layer 23 and the drain semiconductor layer 24 are formed in a self-aligning manner, and an annealing protection film such as SiO ₂ is further laminated on the semiconductor layer, and the temperature is set to 800 ° C. Activation annealing for 20 minutes (Fig. 3
(d)).

Next, after removing the annealing protection film (not shown), the source electrode 26 and the drain electrode 27 are formed by the lift-off method or the like to fabricate the MESFET 20 (FIG. 3 (e)).

Finally, RIE using a chlorine-based gas from the back surface of the semiconductor substrate 10 using the photoresist as a mask.
Alternatively, the GaAs substrate 11 and the non-doped GaAs buffer layer 12 are etched up to the etching stopper layer 13 by wet etching, and the light introducing window 30 is opened under the MESFET 20 to obtain the photodetector as shown in FIG.

In this embodiment, AlGaAs is used as the etching stopper layer 13 for the GaAs substrate 11 and the non-doped GaAs buffer layer 12, but GaP, I
nAs, InP, AlGaP, InGaAs, InAl
Similarly, a large etching selection ratio can be obtained with As or the like. In addition, in this embodiment, the ion implantation type GaAsM is used.
Although ESFET was used, MESFET having an epitaxial growth channel can be manufactured in the same manner.

FIG. 4 shows a second embodiment of the present invention, in which a HEMT is used as a semiconductor electronic device. In the figure, reference numeral 40 denotes a semiconductor substrate, which is formed by laminating a non-doped InP buffer layer 42 and a non-doped InAlAs etching stopper layer 43 on an InP substrate 41. Further, 50 is a HEMT, which is a non-doped InGaAs channel layer 5 on the semiconductor substrate 40.
1, n-type InAlAs electron supply layer 52, semiconductor layer 53 for source, semiconductor layer 54 for drain, gate electrode 55, source electrode 56 and drain electrode 57 are formed. Reference numeral 60 denotes a light introducing window, which is a portion of the semiconductor substrate 40 corresponding to the HEMT 50 and is made of non-doped InP.
The buffer layer 42 is removed.

FIG. 5 shows the manufacturing process of the photodetector of FIG. 4, and the manufacturing method will be described below in accordance with this.

First, non-doped In is deposited on the InP substrate 41.
200 nm of P buffer layer 42, undoped InAlAs
The etching stopper layer 43 is 200 nm thick and is non-doped In
GaAs channel layer 51 of 50 nm, n-type InAlAs
Electron supply layer 52, n-type InAlA for source and drain
The s semiconductor layer and the n-type InGaAs semiconductor layer 58 are
The layers are sequentially laminated by E or MOCVD (FIG. 5 (a)).

Next, using the photoresist as a mask, mesa etching for device isolation is performed by RIE using a chlorine-based gas (FIG. 5 (b)). Next, using the photoresist as a mask, an ohmic electrode material such as AuGe / Ni is deposited and lifted off to form a source electrode 56 and a drain electrode 57 (FIG. 5 (c)).

Next, using the photoresist as a mask, R
The n-type InAlAs semiconductor layer 58 for the source and the drain and the n-type InGaAs semiconductor layer 58 under the gate electrode are removed up to the n-type InAlAs electron supply layer 52 by IE or the like, and the source semiconductor layer 53 and the drain semiconductor layer 54 are removed.
Are formed (FIG. 5 (d)).

Next, using the photoresist as a mask, the Schottky electrode material Ti / Pt / Au is deposited and lifted off to form the gate electrode 55, and the HEMT 50 is manufactured (FIG. 5 (e)).

Finally, from the back surface of the semiconductor substrate 40, using the photoresist as a mask, RIE using chlorine-based gas.
Alternatively, the InP substrate 41 and the non-doped InP buffer layer 42 are etched up to the etching stopper layer 43 by wet etching, and the light introducing window 60 is opened under the HEMT 50 to obtain a photodetector as shown in FIG.

In this embodiment, InAlAs is used as the etching stopper layer 43 for the InP substrate 41 and the non-doped InP buffer layer 42.
Even with nAs, InGaAs, InAlAs, AlGaAs, etc., a large etching selection ratio can be obtained. Further, in this embodiment, even when the GaAs substrate is used, the photodetector can be manufactured by using the same etching stopper layer as in the first embodiment.

FIG. 6 shows a third embodiment of the present invention, in which an HBT is used as a semiconductor electronic device. In the figure, reference numeral 70 denotes a semiconductor substrate, and a non-doped GaAs buffer layer 72 and a non-doped AlGaAs etching stopper layer 73 are laminated on a GaAs substrate 71. Further, reference numeral 80 is an HBT, and on the semiconductor substrate 70, a non-doped GaAs collector semiconductor layer 81, an n-type GaAs semiconductor layer 82, and a p-type AlGaAs.
Base semiconductor layer 83, n-type AlGaAs emitter semiconductor layer 84, base electrodes 85 and 86, emitter electrode 87
And collector electrodes 88 and 89 are produced. Reference numeral 90 denotes a light introducing window, which is formed by removing even the non-doped GaAs buffer layer 72 in the semiconductor substrate 70 in the portion corresponding to the HBT 80.

FIG. 7 shows the manufacturing process of the photodetector shown in FIG. 6, and the manufacturing method will be described below.

First, non-doped G is formed on the GaAs substrate 71.
200 nm of aAs buffer layer 72, undoped AlGa
The As etching stopper layer 73 is 100 nm, the non-doped GaAs collector semiconductor layer 81 is 200 nm, and the n-type Ga is
An As semiconductor layer 82 of 100 nm, a p-type AlGaAs base semiconductor layer 83 of 5 nm, and an n-type AlGaAs emitter semiconductor layer 84 of 20 nm are sequentially laminated by MBE, MOCVD or the like (FIG. 7A).

Next, the semiconductor layer 8 for the emitter is formed by RIE using a chlorine-based gas with the photoresist as a mask.
4 is formed (FIG. 7 (b)). Next, after forming the side walls 101 and 102 using SiO ₂ , an ohmic electrode material AuGe / Ni is deposited and an emitter electrode 87 is formed by Ar milling (FIG. 7 (c)).

Next, using the photoresist as a mask, A
The base electrodes 85 and 86 are formed by r milling, and the base mesa etching is further performed by RIE using a chlorine-based gas to form the base semiconductor layer 83 (FIG. 7D).
).

Next, using the photoresist as a mask, the ohmic electrode material AuGe / Ni is deposited and lifted off to form collector electrodes 88 and 89. Further, using the photoresist as a mask, RIE using chlorine-based gas is performed.
Then, the elements are separated from each other to manufacture the HBT 80 (FIG. 7 (e)).

Finally, RIE using chlorine gas from the back surface of the semiconductor substrate 70 with the photoresist as a mask.
Alternatively, the GaAs substrate 71 and the non-doped GaAs buffer layer 72 are etched up to the etching stopper layer 73 by wet etching, and a light introducing window 90 is opened under the HBT 80 to obtain a photodetector as shown in FIG.

In this embodiment, even when the InP substrate is used, the photodetector can be manufactured by using the same etching stopper layer as in the second embodiment.

[0033]

As described above, according to the photodetector of the present invention, in the photodetector composed of the semiconductor electronic device in which the electrodes are formed only on one surface side of the semiconductor substrate, Since a light introduction window reaching the lower portion of the semiconductor electronic device from the other surface side of the semiconductor substrate is provided in the portion corresponding to the semiconductor electronic device, light incident on the semiconductor electronic device does not have an electrode through the light introduction window. The light can be made incident from the surface side, and the light can be effectively made to enter as compared with the case where the light is made incident from the surface on which the electrode is provided, and the optical coupling coefficient and the light receiving sensitivity can be significantly improved. Further, as compared with the case where a photodiode is used, high speed operation is possible and the amplifying action of the semiconductor electronic device can be utilized.

Further, according to the manufacturing method of the present invention, a step of laminating a second semiconductor layer on the first semiconductor layer so that only the first semiconductor layer can be selectively etched, and a second step
Manufacturing a semiconductor electronic device on the semiconductor layer of
The process comprises a step of etching the first semiconductor layer in a portion corresponding to the semiconductor electronic device to form a light introducing window, and therefore, a process margin is increased by a process similar to that of a via hole, for example, an etching selection ratio of 100 to 1000. The window for introducing light can be stably formed, and a photodetector using a high-performance semiconductor electronic device can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a photodetector of the present invention.

FIG. 2 is a sectional view showing an example of a conventional photodetector.

FIG. 3 is a diagram showing a manufacturing process of the photodetector of FIG.

FIG. 4 is a sectional view showing a second embodiment of the photodetector of the present invention.

FIG. 5 is a diagram showing a manufacturing process of the photodetector of FIG.

FIG. 6 is a sectional view showing a third embodiment of the photodetector of the present invention.

FIG. 7 is a diagram showing a manufacturing process of the photodetector of FIG.

[Explanation of symbols]

10, 40, 70 ... Semiconductor substrate, 11, 71 ... GaAs
Substrate, 12, 72 ... Non-doped GaAs buffer layer, 1
3, 73 ... Non-doped AlGaAs etching stopper layer, 14 ... Non-doped GaAs layer for device fabrication, 20
... MESFET, 21 ... Embedded p layer, 22 ... Channel layer, 23 ... Source semiconductor layer, 24 ... Drain semiconductor layer, 25, 55 ... Gate electrode, 26, 56 ... Source electrode, 27, 57 ... Drain electrode, 30 , 60, 90 ... Window for introducing light, 41 ... InP substrate, 42 ... Undoped InP
Buffer layer, 43 ... Non-doped InAlAs etching stopper layer, 50 ... HEMT, 51 ... Non-doped InG
aAs channel layer, 52 ... n-type InAlAs electron supply layer, 53 ... source semiconductor layer, 54 ... drain semiconductor layer, 80 ... HBT, 81 ... non-doped GaAs collector semiconductor layer, 82 ... n-type GaAs semiconductor layer, 83 ... p-type AlGaAs base semiconductor layer, 84 ... n-type AlGaA
s emitter semiconductor layer, 85, 86 ... base electrode, 87
... Emitter electrodes, 88, 89 ... Collector electrodes.

Claims (2)

[Claims] 1. A photodetector comprising a semiconductor electronic device in which an electrode is formed only on one surface side of a semiconductor substrate, wherein a portion of the semiconductor substrate corresponding to the semiconductor electronic device is provided on the other side of the semiconductor substrate. A photodetector comprising a light introduction window reaching from the surface side to the lower part of the semiconductor electronic device. 2. A step of laminating a second semiconductor layer on the first semiconductor layer, which enables selective etching of only the first semiconductor layer, and a semiconductor electronic device on the second semiconductor layer. A method of manufacturing a photodetector, comprising: a manufacturing step; and a step of etching a portion of the first semiconductor layer corresponding to a semiconductor electronic device to form a light introducing window.