RU2605783C1 - Planar high-voltage photo- and beta-voltaic converter and method of making thereof - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to converters of optical and beta-radiation sources energy into electric energy. Creation of an original planar design of a high-voltage converter is implemented as per a standard microelectronic technology. Peculiar feature of such a design is arrangement of several elements of p-i-n-structures isolated from each other with microchannels and interconnected in series, herewith each structure collects radiation of p-n-junctions on both sides of a silicon plate both from a light source and a beta-source. Such converter can be used in difficult to access places, mines, for power supply of biosensors integrated inside the body, etc., as well as for charging microaccumulators based on chemical current sources with a solid-state electrolyte.

EFFECT: planar photo- and beta-voltaic converter according to the invention provides high value of output EMF voltage.

2 cl, 3 dwg

Description

The invention relates to the field of creating semiconductor devices, in particular to the manufacturing technology of beta-voltaic and photoelectric converters of ionizing radiation into electrical energy (EMF) of high voltage.

There are known designs of planar - three-dimensional - converters of ionizing radiation into electrical energy, which were proposed by Sun W. and Chandrashekhar M.V.S. [1-4] and which use microchannel etching to create vertical pn junctions. This design allows you to increase the surface of the pn junction, on which a radioactive substance is deposited in the channels [1-4] or filled with light-conducting material [1, 2], which allows to increase the generation current in the elements and increase their efficiency proportionally to the area. Such constructions make it possible to obtain a developed surface of slits or channels of silicon wafers with optimal sizes of quasineutral regions and space charge regions (SCR) of p-i-n-diodes in which charge carriers are generated by beta radiation. In order to increase the emf of photo- and beta-voltaic elements, wide-gap materials — GaN, GaP, AlGaAs, and SiC — are used due to their higher temperature resistance [4, 5]. However, the maximum voltage of the EMF of such structures does not exceed the contact potential difference of these materials, which is a disadvantage in the case when a high supply voltage is required.

Moreover, when creating three-dimensional (3D) structures, technologies using wide-gap materials are inferior in performance and efficiency to silicon technology. In particular, the depth of microchannels in silicon is several times greater than in silicon carbide and other materials. The degree of defect formation during the formation of microchannels is also minimal in silicon technology. Moreover, it is in silicon technology that it is most simple and economical to combine a set of two-dimensional elements in one design.

Also known is the technology of dielectric isolation obtained by vertical anisotropic etching of silicon [6], in which the vertical insulating microchannels are realized in silicon with the (110) or (100) orientation and then are filled with a silicon suspension based on an organosilicon polymer. To do this, first use a mask to apply a photo mask pattern, then etch it in a KOH solution at a temperature of 60 ° C, resulting in parallel grooves with a depth of up to 150-200 microns, a width of about 30 microns and a length of several centimeters. Then oxidation is carried out to a depth of 0.5-0.6 μm and in the centrifuge the microchannels are filled with a fine suspension of silicon in a 5% solution of dimethylsiloxane rubber in toluene.

The known design "Silicon single-crystal multi-junction photoelectric transducer of optical and radiation radiation" [7] (Fig. 1), taken as a prototype and containing diode cells with vertical single junctions located perpendicular to the horizontal light-receiving surface and horizontal in the diode cells parallel to the light-receiving surface n ⁺ -p ^- transitions, all transitions being connected into a single structure by metal cathode and anode electrodes. The advantage of this design is the ability to obtain a high output voltage when exposed to light or under the influence of radiation.

A method of manufacturing the design of the prototype, including the formation on the surface of single crystal silicon wafers of vertical single n ⁺ -p ^- -p ⁺ (p ⁺ -n ^- -n ⁺ ) transitions, metallization of the surface of the plates, the assembly of the plates in a column with gaskets made of aluminum foil, fusion in a vacuum oven for cutting the column structure forming the horizontal n ⁺ -p ^- (p ⁺ -n ^-) transitions, accession tokovyvodyaschih contacts svetoprosvetlyayuschego and applying a dielectric coating, wherein prior to the formation on the surface of the plates mon vertical single crystalline silicon n ⁺ p ^- p ⁺ (p ⁺ -n ^- -n ⁺⁾ transitions in the screen plates form additional vertical weakly doped n ⁺ -p ^- (p ⁺ -n ^-) transitions, then form vertical single transitions, then after cutting the plates, form horizontal n ⁺ -p ^- (p ⁺ -n ^- ) transitions, while the concentration of impurities in the additional horizontal n ⁺ -p ^- (p ⁺ -n ^- ) transitions is more than an order of magnitude less impurity concentration in horizontal n ^- -p ⁺ (p ^- -n ⁺ ) transitions, in which the impurity concentration in turn is an order of magnitude less than the impurity concentration in the regions - n ⁺ (p ⁺ ) -type of vertical single transitions.

A common drawback of analogues and prototype is the high leakage currents and low efficiency, which with a low level of generation of charge carriers from a beta source, for example nickel-63, does not allow to obtain EMF values acceptable for practical use.

The aim of the invention is the creation of the design of a planar photo- and beta-voltaic converter with a high value of the output voltage of the EMF.

The goal is achieved by creating a new design of a planar converter, consisting of a series of elements - planar pin structures located on one silicon wafer, connected in series and isolated from each other by areas - through microchannels or slots filled with a finely dispersed suspension of silicon and coated with silicon dioxide, while each pin-structure consists of a lightly doped semiconductor wafer of an -n (-p) -type of conductivity, in which are heavily doped upper and lower, respectively horizontal p ⁺ (n ⁺ ) -regions forming pn junctions of the p-in diode with the plate, while they are interconnected by a vertical p ⁺ (n ⁺ ) -closed region, n ⁺ (p ⁺ ) -contact region to the plate of the -n (-p) -type of conductivity, on the upper and lower surfaces of the horizontal p ⁺ (n ⁺ ) -regions, respectively, are layers of the upper and lower dielectric, on the upper layers of which there are contact windows respectively to n ⁺ (p ⁺ ) - and p ⁺ (n ⁺ ) -contact regions connected to neighboring met allic contacts in series, i.e. an n ⁺ (p ⁺ ) contact region with a p ⁺ (n ⁺ ) contact region of the following structure, with a layer of a radioactive isotope emitting beta particles located on the surface of the lower dielectric.

A manufacturing method consisting in the formation of p ⁺ lower and p ⁺ upper horizontal regions, the thermal oxidation of the wafer surface, the first photolithography and etching of the microchannels, the formation of a vertical p ⁺ layer, the oxidation of the side walls of the channels, the filling of a finely dispersed suspension of silicon microchannels, 2nd photolithography and the formation of the n ⁺ -contact layer, conducting the 3rd photolithography and opening the windows for p ⁺ -contact areas, conducting the 4th photolithography and deposition of metallization layers and the deposition of a radioactive isotope - Nickel-63 - on the lower surface of the plate.

The design of the prototype is shown in Fig. 1, in which diode cells (ДА) - 1, with a light-bleaching coating deposited on them - 2, connected to a single structure by metal cathode - 3 and anode - 4 electrodes, with semiconductor regions located respectively on their surface - 5 n ⁺ (p ⁺ ) -type and - 6 p ⁺ (n ⁺ ) -type of single vertical n ⁺ -p ^- -p ⁺ (p ⁺ -n ^- -n ⁺ ) transitions. On the upper and lower surfaces of ДЯ - 1, respectively, semiconductor regions are located - 7 n ⁺ (p ⁺ ) -type - 8 p ⁺ (n ⁺ ) -type of horizontal n ⁺ -p ^- (p ⁺ -n ^- ) junctions. On the surface of regions of the 5 n ⁺ (p ⁺ ) -type and - 6 p ⁺ (n ⁺ ) -type, respectively, the regions of the 9 p ^- (n ^- ) -type and - 10 n ^- (p ^- ) -type are located, forming with them, respectively, single n ⁺ -p ^- (p ⁺ -n ^- ) - and additional n ⁺ -p ^- (p ⁺ -n ^- ) junctions, on its lower and lateral surfaces there is a dielectric layer - 11 thicker than the mean free path of radiation particles in a dielectric. On the surface of which there is a layer of radioactive metal - 12 thick, equal to the mean free path of electrons in the metal.

The design of the high voltage converter according to the invention is shown in Fig. 2, where a is the structure, b is the topology, and c is the equivalent electrical circuit.

The design has a semiconductor wafer of n (p) type of conductivity - 1, on the upper and lower surfaces of which there are strongly doped upper - 2 and lower - 3 horizontal p ⁺ (n ⁺ ) regions, adjacent to them is vertical p ⁺ (n ⁺ ) -closed region - 4, on the upper surface of the plate there is also n ⁺ (p ⁺ ) -contact region - 5, on the surface of horizontal p ⁺ (n ⁺ ) -regions - 2 and 3, the layers of the upper - 6 and lower - 7 are located dielectric, in microchannels is an insulating fine suspension to emniya - 8, the microchannel walls are covered with thin oxide - 9, the contact pads of adjacent elements are connected by a metallization layer - 10, a layer of a radioactive isotope - metal - 11 is located on the bottom surface of the plate, the design contains several pin-structure elements connected in series, and having contact pads the anode is 12 and the cathode is 13.

Concrete implementation example

The manufacturing technology of the high voltage converter according to the invention is shown in Fig. 3 and consists of the following sequence of technological operations:

a) - form by ion doping of boron with a dose of D = 500 μCool with an energy of E = 40 keV p ⁺ lower and p ⁺ upper horizontal region;

- conduct thermal oxidation of the surface of the plates at a temperature of T = 860 ° C for 60 minutes;

- fix the plate on the quartz holder with the bottom side;

b) - conduct the 1st photolithography and opening windows for etching microchannels;

- etching is carried out in a KOH solution at a temperature of 60 ° C to create slots or through microchannels around each element of the p-i-n structures;

- carry out the formation of a vertical p ⁺ -layer by "deep" diffusion of boron;

c) - carry out the oxidation of the side walls of the channels and in the centrifuge the microchannels / slots are filled with a fine suspension of silicon in a 5% solution of dimethylsiloxane rubber in toluene;

g) - carry out the 2nd photolithography and opening the windows for n ⁺ -contact areas;

- form an n ⁺ -contact layer by ion doping of phosphorus with a dose of D = 300 μCool with an energy of E = 40 keV;

d) - carry out the 3rd photolithography and opening of windows for p ⁺ -contact areas;

- conduct 4th photolithography and deposition of aluminum on the upper surface of the plate;

- remove the quartz holder and deposit the radioactive isotope - nickel-63 - on the lower surface of the plate.

The principle of operation of the converter is based on the ionization of a semiconductor material, for example silicon, by light and / or beta radiation of isotopes (nickel, strontium, cobalt, etc.). The electron-hole pairs formed in this case are separated by the pn junction field in the space charge region (SCR) and create a potential difference on the p ⁺ and n ⁺ regions of the transducer. In this case, part of the electron – hole pairs can be assembled by the pn junction field also in the quasineutral region (CCW) at a distance equal to the diffusion length of the charge carrier. In this case, the converter consists of several elements, each of which is a pin-structure connected in series, which allows to obtain high voltage EMF at the output.

Example of practical implementation of the design

The proposed converter can be implemented on KEF silicon wafers of 5 kΩ · cm with an orientation of (110) according to the technology shown in Fig. 3. In this case, ⁶³ Ni can be selected as an isotopic source, which has a long half-life (100.1 years) and emits electronic radiation with an average energy of 17 keV and a maximum energy of 64 keV, which is practically safe for human health. This energy of electrons is less than the energy of defect formation in silicon (160 keV). In this case, the absorption depth in silicon of electrons with an average energy of 17 keV is approximately 3.0 μm, and for 90% absorption it is 20 μm. These dimensions should correspond to the depths of the pn junctions and the SCR value, which is achieved on typical silicon structures.

Technical advantages of the invention:

- the design of the converter allows you to get several times more power compared to analogs and a conventional pin diode (the dimensions of the n ⁺ -contact region are much smaller than the sizes of p ⁺ -horizontal regions and its contribution can be neglected);

- in the manufacture of an ionizing radiation converter, microelectronic technology is used;

- the thickness of the design of the high voltage converter corresponds to the thickness of the silicon wafer, i.e. 200-400 microns, and therefore can be used for electrical power of biosensors and MEMS;

- the design of the converter allows you to receive electrical energy, both under the influence of light, and under the influence of a beta source - Nickel-63;

- such a high-voltage EMF source will provide direct charging of the battery based on chemical current sources with solid-state electrolyte, for which the charging voltage is 4.5-5 V, even in the absence of lighting;

- such a converter can be used in hard-to-reach places to power control and management systems, for example, in explosive rooms, mines, radioactive storage facilities, to power biosensors, etc .;

- the service life of the converter will be determined by the half-life of the radioactive material, which for ¹⁰⁰ Ni is 100.1 years.

Literature

1. Sun W., Hirschman K. D., Gadeken L. L. and Fauchet P.M. Betavoltaic and photovoltaic energy conversion in three-dimensional macroporous silicon diodes // Physica status solidi (a). 2007. V. 204. N 5. P. 1536-1540.

2. Sun W., Kherani N.P., Hirschman K.D., Gadeken L.L. and Fauchet P.M. A Three-Dimensional Porous Silicon rn Diode for Betavoltaics and Photovoltaics // Advanced Materials. 2005. V. 17. N 10. P. 1230-1233.

3. Chandrashekhar M.V.S., Thomas Ch.I .; Li H., Spencer M.G .; Lal A. Demonstration of a 4H SiC Betavoltaic Cell // Applied Physics Letters. V. 88. N3. 2006. P. 033506. 1-3.

4. Chandrashekhar M.V.S., Thomas Ch.I., Spencer M.G. Betavoltaic cell. USA Patent. US 7939986B2. Pub. date: 05/10/2011.

5. Cheng Z., Zhao Z., San H .; Chen X. Demonstration of a GaN betavoltaic microbattery // Nano / Micro Engineered and Molecular Systems (NEMS). 2011. IEEE International Conference. P. 1036-1039.

6. Guk E.G., Tkachenko A.G., Tokranova H.A. et al. Silicon structures with dielectric insulation obtained by vertical anisotropic etching // Letters in the Journal of Technical Physics. 2001.V. 27. No. 9. S. 64-71.

7. Murashev V.N., Legotin S.A., Legotin A.N., Mordkovich V.N., Krasnov A.A. Silicon single-crystal multi-junction photoelectric converter of optical and radiation radiation // RF Patent 2539109 C1 of 01/10/2015.

Claims (2)

1. The design of a planar high-voltage photo- and beta-voltaic converter, consisting of a series of elements - planar pin structures located on one silicon plate, connected in series and isolated from each other by regions - through microchannels or slots filled with a finely dispersed suspension of silicon and coated with dioxide silicon, with each pin-structure consisting of a lightly doped semiconductor wafer -n (-p) -type of conductivity, in which strongly doped, respectively, upper I and the lower horizontal p ⁺ (n ⁺⁾ type region forming a pn-transitions plate pin-diode, while they are interconnected vertical p ⁺ (n ⁺⁾ region-closed, on the upper surface of the plate is also located n ⁺ (p ⁺ ) -contact region to the plate of the -n (-p) -type of conductivity, on the upper and lower surfaces of horizontal p ⁺ (n ⁺ ) -regions, respectively, are layers of the upper and lower dielectric, on the upper layers of which there are contact windows, respectively, to n ⁺ (p ⁺⁾ - and p ⁺ (n ⁺⁾ regions pin connected to adjacent structures m the metallic contacts in series, i.e., An n ⁺ (p ⁺ ) contact region with a p ⁺ (n ⁺ ) contact region of the following structure, with a layer of a radioactive isotope emitting beta particles located on the surface of the lower dielectric. 2. The manufacturing method of the structure according to claim 1, which consists in forming p ⁺ lower and p ⁺ upper horizontal regions, conducting thermal oxidation of the surface of the plates, conducting the 1st photolithography and etching of the microchannels, forming a vertical p ⁺ layer, oxidizing the side walls of the channels, filling microchannels with a finely dispersed silicon suspension, conducting the 2nd photolithography and forming the n ⁺ -contact layer, conducting the third photolithography and opening the windows for p ⁺ -contact regions, conducting the fourth photolithography and deposition of the layer in metallization and deposition of a radioactive isotope - nickel-63 - on the lower surface of the plate.

Images