JPS5893379A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enhance electron surface density of a group of accumulated electrons and the level of electron mobility by a method wherein the part of a two- layer semiconductor lamination located under a controlling electrode is subjected to electromagnetic wave irradiation as represented by visible light. CONSTITUTION:A channel layer 2 and electron-donative layer 3 are formed on a substrate 1, and alloyed layers 6 are formed by heat treatment, which extend through the electron-donative layers 3 to include the upper part of the channel layer 2. Then, source/drain electrodes 5 are formed on the alloyed layers 6. Next, a controlling electrode 7 is formed on the electron-donative layer 3 and, in the vicinity of the controlling electrode 7, a bonding pad 8 is formed. Application of electromagnetic waves to the controlling electrode 7 with low temperatures maintained results in the enhancement of the electron surface density of an accumulated electron group 4 and the level of electron mobility.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a semiconductor device. For details, please refer to the previous patent application filed by the applicant of this patent application (Japanese Patent Application No. 54-1710).
20, No. 55-82036, etc.).

(2) Technical background High electron mobility transistors have different electron affinities2
A control electrode is used to control the electron surface concentration of a group of electrons (two-dimensional electron gas) that accumulates in the vicinity of one heterojunction surface formed by joining different semiconductors, and a control electrode is provided between the control electrodes. An active semiconductor device that controls the impedance of a conductive path formed by the above-mentioned group of accumulated electrons (two-dimensional electron gas) between a pair of input and output electrodes.

The conditions for a combination of semiconductors that can constitute a high electron mobility transistor are (a) their lattice constants are the same or similar, (b) there is a large difference in electron affinity, and (c) the band Since the gap difference is large, there are many.

In addition, whether a layer made of a semiconductor with high electron affinity is used as an upper layer or a lower layer, it is possible to manufacture a high electron mobility transistor as long as specific conditions are satisfied.

Furthermore, both normally-on type and normally-off type can be manufactured if specific conditions are satisfied.

A high electron mobility transistor is characterized in that the electron mobility of the above stored electron group (two-dimensional electron gas) becomes extremely large, especially at low temperatures.

(3) Conventional technology and problems The magnitude of the electron surface concentration and the magnitude of electron mobility of the accumulated electron group (two-dimensional electron gas) generated near the interface of the above-mentioned two types of semiconductor layers with different electron affinities are The characteristics of high electron mobility transistors, such as pinch-off voltage and source-drain saturation current, depend on the amount of free electrons supplied to the stored electron group (two-dimensional electron gas), so the characteristics of high electron mobility transistors, such as the pinch-off voltage and source-drain saturation current, depend on the two types of electron affinity mentioned above. Once the thickness, n-type impurity concentration, etc. of each layer of the semiconductor layer are determined, it is difficult to determine them accordingly and change them thereafter. By the way, if a high electron mobility transistor is held at a low temperature below 77° and irradiated with electromagnetic waves such as light, it will be exposed to a semiconductor with low electron affinity, which is the electron source of the accumulated electron group (two-dimensional electron gas). It was discovered that an excitation phenomenon occurs inside the gas, increasing the electron surface concentration of the accumulated electron group (two-dimensional electron gas).

Therefore, the applicant of this patent application has completed an invention that aims to change the characteristics of high electron mobility transistors by utilizing this principle, and has filed another patent application (Japanese Patent Application No. 56-03).
No. 2088).

Furthermore, when a high electron mobility transistor is kept at a low temperature of, for example, 77% or less, and is irradiated with electromagnetic waves such as light, not only the electron surface concentration of the accumulated electron group (two-dimensional electron gas) but also the electron mobility decreases. It was confirmed that this operation is also effective for improving the characteristics of high electron mobility transistors.

Therefore, it has been desired to develop a high electron mobility transistor having a configuration that allows effective use of this principle.

(4) Purpose of the Invention The purpose of the present invention is to meet this demand, and in a high electron mobility transistor, the semiconductor double layer in the lower region of the control electrode is irradiated with electromagnetic waves such as light to reduce the accumulation in this region. High electron mobility with a configuration that can improve the electron surface concentration and electron mobility of electron groups (two-dimensional electron gas), thereby improving the characteristics of high electron mobility transistors, such as pinch-off voltage and source-drain saturation current. The purpose of this invention is to provide a transistor.

(5) Structure of the Invention The structure of the first invention included in this application is as follows: (a) A double layer made of two types of semiconductors having mutually different affinities is formed on a semi-insulating semiconductor substrate. , (b) Of these two types of semiconductors, only the semiconductor with low electron affinity contains n-type impurities, and the other semiconductors do not contain impurities, and (c) There is a transparent conductive layer on the semiconductor double layer. A control electrode made of the material indium oxide (IntUa) or silver dioxide (8n02) is provided, and (d) human/output electrodes are formed on both sides of this control electrode.

In this configuration, since the control electrode is translucent, by irradiating electromagnetic waves such as light from above the control electrode, electromagnetic waves such as light can be irradiated into the semiconductor double layer in the lower region of the control electrode. is created, and the accumulated electron group generated in this region (
It is possible to change and improve the electron surface concentration and electron mobility of a two-dimensional electron gas.

By the way, the above-mentioned electromagnetic wave irradiation is performed at a low temperature of, for example, 77 degrees, and the semiconductor device must be kept at that low temperature. Therefore, the semiconductor device according to the present invention must be kept at a low temperature to exhibit the desired characteristics. In order to
It must be maintained in a state where radio waves are irradiated.

The configuration of the second invention included in the present application is that a plurality of semiconductor devices having the above configuration are contained in a single chip, and is of a multi-element type.

In this configuration, it is possible to irradiate each of the plurality of cylinders of unit semiconductor elements contained in one chip with electromagnetic waves of different intensities as desired. It can be a multi-element type including high electron mobility transistors of 1 to 3. Making the characteristics of each unit semiconductor element different between a general type and a multi-element type semiconductor device requires an additional process which is not necessarily easy. In this configuration, this requirement can be met very easily by simply varying the irradiation intensity of electromagnetic waves.

Even in this configuration, the electromagnetic wave irradiation is performed at a low temperature of, for example, 77° C., and the semiconductor device must be maintained at a low temperature, so the semiconductor device according to the second invention must also be maintained at a low temperature, Further, in order to exhibit desired characteristics, it is necessary to maintain a state where electromagnetic waves are irradiated, as in the case of the semiconductor device according to the first invention.

(6) Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described with reference to the drawings to further clarify the structure and unique effects of the present invention. - First, a layer (channel layer) made of gallium arsenide (GaAs) containing no impurities is formed on a substrate made of semi-insulating gallium arsenide (GaAs) containing chromium (Or), etc. Aluminum gallium arsenide (AIG) containing n-type impurities
A high electron mobility transistor having a layer structure obtained by forming a layer (a layer containing aAs) will be described.

The figure is a cross-sectional view showing a completed state of a high electron mobility transistor according to an embodiment of the present invention.

In the figure, 1 is a substrate made of semi-insulating gallium arsenide (GaAs) containing chromium (Cr), and 2
is made of impurity-free gallium arsenide (Ga A
s) (channel layer).

3 is formed thereon with a thickness of 0.1 μm for crystal lattice matching, and is made of aluminum gallium arsenic (A) containing n-type impurities at a concentration of I
This is a layer (electron supply layer) made of IGaAs). In this crystal parameter, channel layer 2 and electron supply layer 3
A group of accumulated electrons (two-dimensional electron gas) 4 is generated in the channel layer 2 near the interface. And at 77°K,
Its electronic surface concentration is 5 x 10"/can" and its electron mobility is 1. I x 195cm2/Vsec
Met. The above steps can be performed continuously using molecular beam epitaxial growth.

5 is gold/germanium/gold (Au-Ge/Au)
The input-output electrode has a thickness of 0.3 μm and can be selectively formed in this region using a vacuum evaporation method and a lift-off method. Thereafter, heat treatment is performed for 1 minute in hydrogen (H2) gas at 4500C to form an alloyed layer 6, forming an input/output electrode 5 and a group of accumulated electrons (two-dimensional electron gas).
Ohmic contact with the channel layer 2 containing 4 is realized. Next, a thin layer of indium oxide (In20B) with a thickness of 0.1 μm is formed using a sputtering method using a radio frequency voltage, and is formed using a photolithography method to form the control electrode 7. form. In order to facilitate bonding with this control electrode 7,
A layer of Au (Au) having a thickness of about 0.3 μm is formed, and a bonding portion 8 is formed around the transparent control electrode 7 using a lift-off method. In this state, a high electron mobility transistor according to the prior art was completed, and in this example, the Vintio 7 voltage was measured at 77°K and was 0.5 μ.

Here, the high electron mobility transistor in this prior art is kept at a low temperature and white light can be irradiated at 77°.
At K, the electron surface concentration of the accumulated electron group (two-dimensional electron gas) is 9 X 10"/cm2, and the electron mobility is 1
．． As a result, the pinch-off voltage increased by 0.7 V from the previously measured 0.5 V at 77°K.

As is clear from this example, according to the present invention, electromagnetic waves can be irradiated into the electron supply layer made of a semiconductor with low electron affinity through the transparent control electrode, and as a result, the accumulated electrons in this region By improving the electron surface concentration and electron mobility of the group (two-dimensional electron gas), it is possible to manufacture a high electron mobility transistor with improved characteristics such as pinch-off voltage and source-drain saturation current.

According to the present invention, it is possible to not only improve characteristics such as pinch-off voltage and source-drain saturation current, but also to change a normally-off type high electron mobility transistor to a normally-on type high electron mobility transistor. You can also do it.

Next, a plurality of high electron mobility transistors having the configuration shown in the figure are formed on a simple chip, and at a low temperature,
The second invention has a structure in which each unit semiconductor element is irradiated with electromagnetic waves having different intensities, but it is clear that there is no need to show examples with reference to the drawings, so
Drawings will be omitted and the unique effects of the present invention will be mainly explained. It is not necessarily easy to form elements with multiple cylinders having different characteristics. In the conventional technology, in order to form multiple elements with different pinch-off voltages on a single chip, the impurity concentration of the channel layer was made to be different. The use of methods such as ion implantation was essential. On the other hand, in order to simultaneously form a normally-off type element and a normally-on type element on a single chip...
Since it is necessary to form a type channel region and an n-type channel region, it is necessary to selectively introduce n-type impurities and p-type impurities. However, according to the present invention, the desired area can be removed by simply changing the intensity of the irradiated electromagnetic waves. By selectively irradiating electromagnetic waves to the semiconductor, it is extremely easy to create a multi-element semiconductor containing multiple elements with different characteristics on a single chip, after not only the formation of the pigeon but also the formation of the electrodes has been completed. The device can be manufactured.

(7) As described in the detailed description of the invention, according to the first invention included in the present application, in a high electron mobility transistor, electromagnetic waves such as light are irradiated to the semiconductor double layer in the lower region of the control electrode. ,
This configuration improves the electron surface concentration and electron mobility of the accumulated electron group (two-dimensional electron gas) in this region, thereby improving the characteristics of high electron mobility transistors, such as pinch-off voltage and source-drain saturation current. A high electron mobility transistor can be provided.

Further, according to a second invention included in the present application, a plurality of high electron mobility transistors according to the above invention are contained in a simple chip, and a plurality of types of high electron mobility transistors having different characteristics are integrated into a single chip. It is possible to provide a multi-element semiconductor device that is included in a chip.

[Brief explanation of drawings]

The figure is a sectional view showing a completed state of a high electron mobility transistor according to an embodiment of the first invention included in the present application. 1... Semi-insulating substrate (gallium arsenide substrate containing chromium etc.), 2... Layer made of a semiconductor with high electron affinity (gallium arsenide layer containing no impurities), 3... ... Layer made of a semiconductor with low electron affinity (aluminum gallium arsenide layer containing n-type impurities), 4 ... Accumulated electron group (two-dimensional electron gas), 5 ...・Input/output electrode, 6...
Alloyed layer, 7... Transparent control electrode (control electrode made of indium oxide), 8... Control electrode bonding member (annular member made of gold).

Claims (4)

[Claims] (1) It has a double layer made of two types of semiconductors with different electron affinities formed on a semi-insulating semiconductor substrate, and among the two types of semiconductors, the semiconductor with the smaller electron affinity has an n-type impurity. However, the semiconductor with high electron affinity does not contain impurities, and has a control electrode made of indium oxide or silver dioxide formed on the double layer made of the two types of semiconductors, and the control electrode An active semiconductor device having input and output electrodes sandwiched between the two. (2) the active semiconductor device is maintained at a low temperature;
The active electrode according to claim 1, wherein the control electrode is irradiated with electromagnetic waves and a group of electrons (two-dimensional electron gas) is accumulated near the interface between the double layers made of the two types of semiconductors. Semiconductor equipment. (3) It has a double layer made of two types of semiconductors with different electron affinities formed on a semi-insulating semiconductor substrate, and among the two types of semiconductors, the semiconductor with the smaller electron affinity contains n-type impurities. However, the semiconductor with high electron affinity does not contain impurities, and has a control electrode made of indium oxide or silver dioxide formed on a layer made of the two types of semiconductors, and the control electrode is A multi-element semiconductor device in which a single chip contains a plurality of active semiconductor devices having input and output electrodes formed in a sandwiched manner. (4) The plurality of cylinders of active semiconductor devices are maintained at a low temperature, and at least one of the plurality of cylinders of active semiconductor devices is maintained at a low temperature.
In particular, a group of electrons (two-dimensional electron gas) is accumulated in the vicinity of the interface between the double layers made of the two types of semiconductors of the active semiconductor device when electromagnetic waves are irradiated to the 1,000 control electrodes. A multi-element semiconductor device according to claim 3.