Semiconductor ultraviolet radiation sensor based on aluminium nitride and method of making said sensor

FIELD: physics, semiconductors.

SUBSTANCE: invention relates to microelectronics and can be used in designing semiconductor ultraviolet radiation sensors. A semiconductor UV radiation sensor has a substrate on which there are series-arranged wiring layer made from TiN, a photosensitive AlN layer, and an electrode system which includes a platinum rectifying electrode which is semi-transparent in the C-region of UV radiation, connected to the AlN layer to form a Schottky contact, first and second leads for connecting to an external measuring circuit, where the first lead is connected to the wiring layer and the second to the rectifying electrode. The method of making a semiconductor UV radiation sensor involves successive deposition of a wiring TiN layer and a photosensitive AlN layer onto a substrate through reactive magnetron sputtering on a general processing unit in a nitrogen-containing gas medium with subsequent formation of a platinum rectifying electrode which is semitransparent in the C-region of UV radiation, connected to the photosensitive AlN layer to form a Schottky contact, and leads for connecting the rectifying electrode and the wiring layer to an external measuring circuit. The wiring and photosensitive layers are deposited continuously without allowing cooling down of the substrate. The platinum rectifying electrode is made through three-electrode ion-plasma sputtering of a platinum target at pressure of 0.5-0.6 Pa for 4-6 minutes, target potential of 0.45-0.55 kV and anode current of 0.8+1.2 A. Sensitivity of the end product is equal to 65-72 mA/W.

EFFECT: increased sensitivity of the end product.

2 cl, 2 dwg, 1 tbl

 

The invention relates to microelectronics and can be used in technology design of semiconductor sensors (TTD) ultraviolet radiation (UVR) - sensitive layer made of aluminum nitride (A1N).

Known sensor UFI containing semiconductor structure with one barrier layer comprising non-crystalline semiconductor with high resistivity semiconductor substrate of the first conductivity type, the source voltage and electrode system (ES), formed with a possibility of bias voltage from a voltage source to a semiconductor structure (JP 4-81352, H01L 31/09, 1992).

Also known TTD UFI containing a substrate of monocrystalline sapphire, bipolar grown on a substrate a photosensitive layer of AlN and ES performed with the formation of high-resistance parallel plots in the AlN layer, and ES formed in the plane of the section of the substrate with the semiconductor layer (RU 2155418, H01L 31/09, 2000).

However, these sensors cannot operate in the generator mode, requiring the installation of the source of electric power to the external measuring circuit, which hampers their use in the field.

The main trend of development of this type of equipment is to increase the sensitivity of the target product by covering podlog and mounting layer, perform the function of dislocation filter, providing a high structural perfection of the photosensitive layer of AlN.

This tendency is implemented in TTD UFI on the basis of aluminum nitride containing substrate on which are successively located mounting layer made of low-temperature aluminum nitride imperfect structure of gallium nitride or of a solid solution of n-Al(Ga)N, and a photosensitive layer of aluminum nitride. The sensor also contains an electrode system including an ohmic electrode connected to the mounting layer and a rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of (US 20080087914, H01L 1/00,21/00,2008).

Such a sensor has a low sensitivity due to the influence of interference associated with the recombination of charge carriers in the interelectrode space. In addition, it is ethnological in manufacturing.

Closest to the claimed is TTD UFI on the basis of aluminum nitride containing substrate on which are successively located mounting layer made of titanium nitride, and a photosensitive layer of aluminium nitride, and an electrode system comprising a platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of the first and second leads for Pris is unity to an external measuring circuit, the first output is connected with a mounting layer, and the second output is connected with the rectifying electrode (Spivak A. M. the Formation of a multilayer photodetector structures ultraviolet range based on thin films of aluminum nitride. - “Vacuum technology”, 2008, Vol.18, No. 1, s-15). Here, the mounting layer simultaneously performs the function of the ohmic electrode, which has the consequence of increasing the sensitivity of the sensor by reducing the interelectrode resistance, as well as simplifying its design.

In the design of the prototype area of the rectifying electrode should be large to increase the photocurrent. However, this requirement prevents the penetration of UVR to the area of the photosensitive layer, the private data electrode. Therefore, the photosensitivity of a prototype sensor continues to remain low.

The technical objective of the proposed TTD UFI is to increase its photosensitivity.

The solution of the stated technical problem is that the design of the DPP UFI containing substrate on which are successively located mounting layer made of titanium nitride, and a photosensitive layer of aluminium nitride, and an electrode system comprising a platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with education to the of intacta of Schottky, first and second terminals for connection to an external measuring circuit, and the first output is connected with a mounting layer, and the second output is connected with the rectifying electrode is made the following change: a rectifying electrode is made semi-transparent in the UV range of the radiation.

Transparency rectifying electrode depends on the technology that is discussed later.

The causal link between an amendment and achieved technical result is that the translucent electrode provides the ability to receive UFI close them part of the surface of the photosensitive layer of the sensor, which is a consequence of the sharp increase its photosensitivity.

A known method of manufacturing TTD UFI, providing for the formation of metal electrodes on the surface of the substrate, followed by coating the working surface of the substrate and electrodes of a thin film A1N without using the mounting layer using reactive sputtering or chemical vapor deposition (WO 2008133920, H01L 23/29; H01L 23/28, 2008).

There is also known a method of manufacturing TTD UFI by applying a layer of conductive material on a substrate of monocrystalline sapphire, followed by the formation therein of ES using photolithography. Next PR is harass epitaxy A1N and attach ES to an external measuring circuit (EN 2155418, H01L 31/09,2000).

However, the target product, obtained by these methods have low sensitivity due to structural imperfections of the photosensitive layer of AlN.

To ensure the structural perfection of the photosensitive layer A1N closest analogue of the method involves sequential deposition on a substrate by deposition from the gas phase ORGANOMETALLIC compounds mounting layer of low-temperature aluminum nitride imperfect structure of gallium nitride or of a solid solution of n-Al(Ga)N at a temperature of 800°C or more and a photosensitive layer of aluminum nitride at a temperature of over 1000°C, followed by formation of the electrode system, comprising ohmic electrode connected to the mounting layer and a rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of, and conclusions for connecting the rectifying and ohmic electrodes to an external measuring circuit (US 20080087914, H01L 31/00, 21/00, 2008).

The disadvantage of this method is the low photosensitivity of the obtained target product. In addition, this method has low adaptability, until incompatibility with standard silicon processes microtechnology due to the need for processes of applying Assembly and the photosensitive layer at high temperature is x, that is not possible to pre-form other integrated elements (for example, elements of the processing circuit photosignal) on a single chip with the sensor.

Closest to the claimed is a method for manufacturing RPE UFI on the basis of aluminum nitride, which provides the consistent application of the mounting substrate layer of titanium nitride and a photosensitive layer of aluminium nitride reactive magnetron sputtering on a common process unit in a nitrogen-containing gas environment with the subsequent formation of aluminum or platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of, and conclusions to connect rectifying electrode and the circuit layer to an external measuring circuit electrode (Spivak A. M. the Formation of a multilayer photodetector structures ultraviolet range based on thin films of aluminum nitride. - “Vacuum technology”, 2008, Vol.18, No. 1, s-15).

With the technical implementation of this method application installation and photosensitive layers of reactive magnetron sputtering is possible in well-known modes, in particular, at a relatively low temperature of the substrate to 350°C, which ensures compatibility with standard silicon processes microtechnology.

However, senses the activity of the target products manufactured prototype by the way, continues to be low due to the reduction of the active area of the photosensitive layer due to the opacity covering this area of the layer rectifying electrode.

The technical objective of the proposed method is to increase the photosensitivity of the target product.

The solution of the stated technical problem is that in the method of manufacturing TTD UFI on the basis of aluminum nitride, which provides the consistent application of the mounting substrate layer of titanium nitride and a photosensitive layer of aluminium nitride reactive magnetron sputtering on a common process unit in a nitrogen-containing gas environment with the subsequent formation of platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of, and conclusions to connect rectifying electrode and the circuit layer to an external measuring circuit, is amended as follows:

1) the operation of application installation and photosensitive layers produced continuously, preventing cooling of the substrate;

2) platinum rectifying electrode form a semi-transparent in the UV range three-electrode ion-plasma sputtering of a platinum target at a pressure of 0,5÷0,6 PA for 4÷6 minutes, is the potential target of 0.45÷0,55 kV and anode current 0,8÷1,2 A.

Continuous operations application installation and photosensitive layers of reactive magnetron sputtering on one process unit in a nitrogen-containing gas environment, preventing cooling of the substrate, provides the most high structural perfection of the photosensitive layer. Otherwise, on the surface of the TiN time to receive the microparticles degrade the structure of the AlN layer, which reduces the sensitivity and reliability of the target product, until zakolachivaniya electrodes.

Figure 1 shows the proposed scheme TTD UFI; figure 2 presents the spectral response of the sensor to the example above; table 1 presents data on the sensitivity of the DPP by UFI in the short circuit mode depending on the values of the technological parameters of the operation of applying a rectifying electrode.

TTD UFI (figure 1) contains a silicon substrate 1, on which are positioned successively mounting layer 2, made of TiN, and a photosensitive layer 3, made of AlN, and ES, including translucent in the field of UFI platinum rectifying electrode 4 connected to the photosensitive layer 3 with the formation of the Schottky contact of. For connection to an external measuring circuit is made conductive conclusions 5 and 6, while the output 5 is welded to the mounting layer 2 that performs this product t is the train function of the ohmic electrode, and pin 6 is welded to the rectifying electrode 4.

The irradiation-side translucent electrode 4 UFI C-region in a photosensitive layer 3 are generated charge carriers due to interband excitation UFI. These charge carriers are separated by the electric field of the barrier Schottky, resulting in an external measuring circuit photocurrent flows (in this case, refers to the short-circuit current), the value of which depends on the power source UFI.

In the presence of the external measuring circuit of the source of EMF, the sensor operates in the mode back included photodiode whose resistance depends on the power source UFI.

This TTD UFI manufactured as follows. On the silicon substrate 1 is applied mounting layer 2 of titanium nitride reactive magnetron sputtering of titanium target at a constant current of 2 a And the nitrogen-containing gas (AG 70 volume. Percent; N230 volume. %) at a pressure of 1 PA and a temperature of the substrate 330°C for 12 minutes Grown layer of TiN has a thickness of 0.6 μm and a specific resistance of 40 µohm·see Immediately upon completion of this transaction on the same technology installed at the same temperature, pressure and composition of the gas mixture on the mounting layer 2 is applied photosensitive layer 3 of aluminium nitride magnetron sputtering an aluminum target AC cha is the frequency of 13.56 MHz and a discharge power of 500 watts for 6 hours The thickness of the grown layer A1N is 0.5 μm. The density of through defects in it not more than 10 000 cm-2. The place of connection output 5 to the layer 2, layer 3 is etched with a weak solution of KOH. Next on the open surface of photosensitive layer 3 is formed of platinum rectifying electrode 4, forming a barrier of a Schottky between the electrode and the photosensitive layer 3.

Translucency platinum rectifying electrode 4 in the UV range is ensured by the mode of its formation. Rectifying electrode 4 form a three-electrode ion-plasma sputtering of a platinum target. In this example, the operation of forming a rectifying electrode 4 are provided at different pressures in the range from 0.4 to 0.7 PA, exposure in the range of from 3 to 8 min, the potential target in the range from 0.4 to 0.6 kV and anode current in the range from 0.6 to 1.4 A. After that, the mounting layer 2 and the rectifying electrode 4 are welded conclusions 5 and 6, respectively, are made of AU.

As can be seen from the table, the target device is operable when the following values of technological parameters of ion-plasma sputtering of a platinum target: pressure 0,5÷0,6 PA; exposure time 4÷6 min; the potential target of 0.45÷0,55 kV; anode current 0,8÷1,2 A. When specified values of technological parameters photosensitivity of the target product is Oia in the short circuit mode is 65÷72 mA/W, that, according to tests carried out in the Centre of microelectronics technology, more than 9 times, surpasses the photosensitivity of prototype products. In the optimal mode, the transparency of the rectifying electrode reaches 34%. At the bottom beyond the values of technological parameters it is impossible to ensure the integrity of the rectifying electrode, and at the top beyond the values of technological parameters photosensitivity decreases sharply due to weak transparency rectifying electrode. The spectral absorption region of the DPP in this example, is in the range from 210 to 290 nm (figure 2).

Thus, the use of the proposed technical solutions in comparison with the prototype allows to increase the sensitivity of the DPP by UFI. The technical result that is derived from these results is the natural selectivity in the spectrum of signals received UFI.

Specifications TTD UFI depending on the mode of application rectifying electrode
The value of the mode parametersPhotosensitivity, mA/WNote (transparent electrode, %)
is providing, PAexposure time, minpotential targets kVanode current, a
0,430,400,632Pt covers <50% of the photosensitive layer
0,540,450,865
0,5550,501,07234
0,660,551,271
0,780,601,418<10

1. A semiconductor sensor ultraviolet radiation on the basis of aluminum nitride containing substrate on which are successively located mounting layer made of titanium nitride, and a photosensitive layer nitidulinae, and electrode system comprising a platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of the first and second terminals for connection to an external measuring circuit, and the first output is connected with a mounting layer, and the second output is connected with the rectifying electrode, characterized in that the rectifying electrode is made semi-transparent in the UV range of the radiation.

2. A method of manufacturing a semiconductor sensor ultraviolet radiation on the basis of aluminum nitride, which provides the consistent application of the mounting substrate layer of titanium nitride and a photosensitive layer of aluminium nitride reactive magnetron sputtering on a common process unit in a nitrogen-containing gas environment with the subsequent formation of platinum rectifying electrode connected to the photosensitive layer of aluminium nitride with the formation of the Schottky contact of, and conclusions to connect rectifying electrode and the circuit layer to an external measuring circuit, wherein the operation of applying Assembly and the photosensitive layer is produced continuously, preventing cooling of the substrate, while platinum rectifying electrode form a semi-transparent in the UV range three electrogram ion-plasma sputtering of a platinum target at a pressure of 0,5÷0,6 PA for 4÷6 min, the potential target of 0.45÷0,55 kV and anode current 0,8÷1,2 A.



 

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