This application claims priority from Korean Patent Application No. 10-2011-0085819, filed on Aug. 26, 2011 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field
Apparatuses and methods consistent with exemplary embodiments relate to micro conversion devices, and more particularly, to energy conversion devices and methods of manufacturing and operating the same.
2. Description of the Related Art
An output voltage higher than an input voltage may be obtained by using a boost converter. A charge pump and a voltage doubler are known as boost converters.
In a charge pump, since a gain is proportional to the number of stages, the number of stages provided according to steps needs to be increased in order to obtain a high gain.
In a voltage doubler, since a complementary switching signal is needed, switching loss may occur. In a charge pump and a voltage doubler, a gain in a unit stage is less than 2.
A boost converter may be manufactured on a substrate along with a circuit by using microelectromechanical systems (MEMS). However, since MEMS using a complementary metal-oxide-semiconductor (CMOS) process may use only a poly-material, MEMS have a material-related problem. In addition, a stress problem may occur according to a material and a thermal profile, and a passivation problem may also occur.
Also, related art MEMS devices are manufactured to meet specific purposes. Accordingly, it is difficult to use an existing MEMS device for purposes other than its given purpose.
One or more embodiments provide an energy conversion device that may have a high gain and high reliability and may be used for various purposes.
Further, one or more embodiments provide methods of manufacturing such an energy conversion device.
Further still, one or more embodiments provide methods of operating such an energy conversion device.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of exemplary embodiments.
According to an aspect of an embodiment, there is provided an energy conversion device including: a monolithic single-crystal silicon layer that includes a plurality of doping regions; a vibrator disposed in the single-crystal silicon layer and is connected to a doping region of the plurality of doping regions; a first diode that is a PN junction diode and allows an input signal applied to the vibrator to pass therethrough; and a second diode that is a PN junction diode and allows a signal output from the vibrator to pass therethrough.
The single-crystal silicon layer may include a space therein that is sealed, and the vibrator is disposed in the space.
The plurality of doping regions may include first through third doping regions that are sequentially disposed, and the third doping region may include a p-type doping region and n-type doping regions that form the first and second diodes, and the energy conversion device may further include a doping region that separates a remaining portion of the third doping region and the first and second diodes.
The third doping region may include a plurality of through-holes that are connected to the space.
The energy conversion device may further include a sealing layer that is disposed on the third doping region to cover the plurality of through-holes.
The sealing layer may include a plurality of contact holes through which the first diode, the second diode, and a portion of the third doping region between the first diode and the second diode are exposed.
The energy conversion device may further include first through third electrodes that are disposed on the sealing layer to be spaced apart from each other, wherein the first through third electrodes are connected to the first diode, the second diode, and the third doping region through the plurality of contact holes.
Adjacent doping regions among the first through third doping regions may be oppositely doped.
The vibrator may include a first diaphragm and a second diaphragm that are connected to each other.
The vibrator may include a portion that is doped to have the same conductivity as a conductivity of the doping region to which the vibrator is connected, and a portion that is doped to have the same conductivity as conductivities of the doping regions to which the vibrator is not connected.
The second diaphragm may include two portions that are oppositely doped.
The first diaphragm may include a plurality of through-holes.
A doping region facing the second diaphragm and the vibrator may constitute a variable capacitor.
The second diaphragm and the doping region facing the second diaphragm may be parallel to each other at all times.
The energy conversion device may further include an insulating layer that has fixed polarization charges and is disposed on a surface of the vibrator.
According to an aspect of another embodiment, there is provided a method of operating an energy conversion device including a monolithic single-crystal silicon layer that includes a plurality of doping regions, a vibrator that is disposed in the single-crystal silicon layer and connected to a doping region of the plurality of doping regions, a first diode that is a PN junction diode and allows an input signal applied to the vibrator to pass therethrough, and a second diode that is a PN junction diode and allows a signal output from the vibrator to pass therethrough, the method including: driving the vibrator; and outputting, through the second diode, an output signal according to the driving of the vibrator.
The driving of the vibrator may include applying an input voltage to the first diode.
The method may further include applying a synchronizing signal to a region that is electrically separated from the first diode and the second diode in a doping region between the first diode and the second diode to make the output signal higher than the input voltage.
The vibrator may be driven by a force applied to the energy conversion device, and the output signal may be used as data for measuring a physical quantity of the force.
An insulating layer having fixed polarization charges may be disposed on a surface of the vibrator to use the energy conversion device as an energy harvester.
The single-crystal silicon layer may include a space therein that is sealed, and the vibrator may be disposed in the space.
The plurality of doping regions may include first through third doping regions that are sequentially disposed, wherein the third doping region includes a p-type doping region and n-type doping regions that form the first diode and the second diode, wherein the energy conversion apparatus further includes a doping region that separates a remaining portion of the third doping region and the first diode and the second diode.
The vibrator may include a region that is doped to have the same conductivity as a conductivity of the doping region to which the vibrator is connected, and a portion that is doped to have the same conductivity as conductivities of the doping regions to which the vibrator is not connected.
According to an aspect of another embodiment, there is provided a method of manufacturing an energy conversion device including: forming a first oxidized region on a first silicon layer that is single-crystal and is doped with a p-type doping material or an n-type doping material; growing, on the first silicon layer, a second silicon layer that is doped in a manner opposite to that of the first silicon layer; forming a second oxidized region that is connected to the first oxidized region and surrounds portions of the first silicon layer and the second silicon layer, wherein the portion of the second silicon layer surrounded by the second oxidized region is connected to a portion of the second silicon layer formed over the second oxidized region; growing, on the second silicon layer, a third silicon layer that is a single-crystal layer and is doped in a manner opposite to that of the second silicon layer; forming, on the portion of the second silicon layer formed over the second oxidized region, a third oxidized region that is connected to the second oxidized region, wherein the third oxidized region is formed by oxidizing a top surface of the second silicon layer; forming, on the third silicon layer, a first PN junction diode and a second PN junction diode that are spaced apart from the third oxidized region and are electrically separated from each other by a remaining portion of the third silicon layer; forming a vibrator that is spaced apart from the first silicon layer and the third silicon layer and is connected to only the second silicon layer by removing oxides of the first through third oxidized regions; and sealing portions from which the oxides are removed, wherein the second silicon layer and the third silicon layer are formed by using epitaxial growth.
The forming of the second oxidized region may include: forming a twenty first oxidized region that is connected to the first oxidized region at a position higher than a position of the first oxidized region outside the first oxidized region; and forming a twenty second oxidized region that is connected to the twenty first oxidized region to be parallel to the first oxidized region at a position higher than a position of the twenty first oxidized region over and within the first oxidized region, wherein a middle portion of the twenty second oxidized region remains as a non-oxidized portion.
The forming of the third oxidized region may include: forming, on the second silicon layer, a thirty first oxidized region that is connected to the second oxidized region at a position higher than a position of the second oxidized region; and forming, on the second silicon layer, a thirty second oxidized region that is connected to the thirty first oxidized region at a position higher than a position of the thirty first oxidized region, wherein the thirty second oxidized region is formed by oxidizing the entire second silicon layer between the thirty first oxidized region and the third silicon layer.
The thirty second oxidized region may extend to the third silicon layer.
The forming of the first and second PN junction diodes may include: forming a first n-type doping region that is connected to the second silicon layer and is spaced apart from the third oxidized region on the third silicon layer at a side of the third oxidized region; forming a second n-type doping region that is connected to the second silicon layer and is spaced apart from the first n-type doping region on the third silicon layer between the third oxidized region and the first n-type doping region, wherein the second n-type doping region is formed on the third silicon layer at the side of the third oxidized region to be connected to the second silicon layer; forming a third n-type doping region that is not connected to the second n-type doping region and the second silicon layer outside the second n-type doping region on the third silicon layer at another side of the third oxidized region; and forming a p-type doing region on the first n-type doping region formed on the third silicon layer at the one side of the third oxidized region, wherein the first n-type doping region and the second n-type doping region are simultaneously formed.
The forming of the vibrator may include: forming through-holes, through which the third oxidized region is exposed, in the third silicon layer; and wet etching oxides of the first through third oxidized region through the through-holes.
The first through third oxidized regions may be formed by: implanting oxygen ions; and annealing a resultant structure obtained after the oxygen ions are implanted.
The sealing may include forming a sealing layer that is formed on the third silicon layer to seal the through-holes.
The method may further include: forming on the sealing layer a plurality of through-holes, through which the first PN junction diode and the second PN junction diode are exposed and the third silicon layer between the first PN junction diode and the second PN junction diode is exposed; and forming on the sealing layer a first electrode that is connected to the exposed first PN junction diode, a second electrode that is connected to the exposed second PN junction diode, and a third electrode that is connected to the exposed third silicon layer.
These and/or other aspects will become apparent and more readily appreciated from the following description of embodiments, taken in conjunction with the accompanying drawings of which:
Exemplary embodiments will now be described more fully with reference to the accompanying drawings. Thicknesses of layers or regions shown in the drawings are exaggerated for clarity.
Referring to
The first doping region 20 is a region doped with a p-type doping material, though it is understood that another embodiment is not limited thereto. For example, according to another embodiment, the first doping region 20 may include an n-type doping material instead of the p-type doping material. The second doping region 30 is disposed on the first doping region 20. The second doping region 20 is a region doped with an n-type doping material, though it is understood that another embodiment is not limited thereto. For example, according to another embodiment, the second doping region 20 may include a p-type doping material instead of the n-type doping material. The first and second diaphragms 32 and 34 extend from the second doping region 30. Accordingly, the first and second diaphragms 32 and 34 may be portions of the second doping region 30.
The first sealing layer 22 is disposed between the first and second doping regions 20 and 30. The first sealing layer 22 is connected to the first and second doping regions 20 and 30. The first sealing layer 22 is disposed on a portion of the first doping region 20. The first sealing layer 22 may be, for example, a silicon oxide layer. The third doping region 40 is disposed on the second doping region 30. A portion of the third doping region 40 is connected to the second doping region 30. The third doping region 40 includes a plurality of through-holes 52 (see
The second sealing layer 50 is formed on the third doping region 40. The second sealing layer 50 is filled in the plurality of through-holes 52 and covers the plurality of through-holes 52. It is understood that the second sealing layer 50 may be filled in all or some of the plurality of through-holes 52. The third doping region 40 may include fourth, fifth, and sixth doping regions 42, 44, and 46 that are spaced apart from one another in a horizontal direction. Doping materials of the fourth, fifth, and sixth doping regions 42, 44, and 46 may be the same as a doping material of the second doping region 30. The fourth and fifth doping regions 42 and 44 are connected to the second doping region 30. The sixth doping region 46 is spaced apart from the second doping region 30. The third doping region 40 is disposed between the second doping region 30 and the sixth doping region 46. Since the third doping region 40 and the sixth doping region 46 are silicon regions respectively doped with p-type and n-type materials, the third doping region 40 and the sixth doping region 46 may constitute a PN junction diode (hereinafter, referred to as a second diode).
The plurality of through-holes 52 are formed between the fifth doping regions 44, which are spaced apart from each other. The fourth doping region 42 is connected to the second doping region 30, and is surrounded by the third doping region 40. The fourth doping region 42 may include a seventh doping region 48. The seventh doping region 48 may be disposed within the fourth doping region 42. The seventh doping region 48 contacts the second sealing layer 50, and a bottom and a side wall of the seventh doping region 48 are surrounded by the fourth doping region 42. The seventh doping region 48 may be a silicon region doped with a p-type doping material. The fourth doping region 42 may be a silicon region doped with an n-type doping material. Accordingly, the fourth doping region 42 and the seventh doping region 48 may constitute a PN junction diode (hereinafter, referred to as a first diode).
The fifth doping regions 44 are regions for separating the first diode and the second diode in the third doping region 40. Directions of the first diode and the second diode may be opposite to each other. The first diode and the second diode are connected to each other through the first diaphragm 32. The space 60 is formed between the first doping region 20 and the third doping region 40. The space 60 may be disposed under the plurality of through-holes 52. The space 60 may be a place where the first diaphragm 32 and the second diaphragm 34 vibrate. The space 60 is sealed by the first doping region 20, the second doping region 40, the first sealing layer 22, and the second sealing layer 50. The first diaphragm 32 and the second diaphragm 34 are connected to each other via a connection pillar 36. The first diaphragm 32 is disposed over the second diaphragm 34. The first diaphragm 32 and the second diaphragms 34 may serve as a single vibrator 32+34.
Before the energy conversion device starts operating, the first diaphragm 32 and the second diaphragm 34 may be parallel to each other. While the energy conversion device operates, the first diaphragm 32 and the second diaphragm 34 may vibrate in the space 60. The first diaphragm 32 and the second diaphragm 34 may vibrate due to an electrical signal applied to the energy conversion device, momentum applied to the energy conversion device, or an external physical force or impact for accelerating the energy conversion device. Though the first diaphragm 32 vibrates in the space 60, the first diaphragm 32 and the third doping region 40 are sufficiently spaced apart from each other so as not to contact each other. The first diaphragm 32 and the second doping region 30 may be disposed at the same level in the horizontal direction. The first diaphragm 32 is connected to the second doping region 30. The first diaphragm 32 may be a portion of the first doping region 30. A plurality of through-holes 32h may be formed in the first diaphragm 32.
The connection pillar 36 may be formed of the same material as that of the first diaphragm 32. The second diaphragm 34 may be disposed at the same level as the first sealing layer 22 in the horizontal direction. The second diaphragm 34 and the first doping region 20 are spaced apart from each other. While the energy conversion device operates, the second diaphragm 34 may instantly contact the first doping region 20. The second diaphragm 34 may include a lower layer 20a and an upper layer 30a disposed on the lower layer 20a. The lower layer 20a and the upper layer 30a are monolithic and connected to each other. The lower layer 20a and the upper layer 30a may be formed of the same material and may be doped with different doping materials. The lower layer 20a may be formed of the same material as that of the first doping region 20, for example, a single-crystal silicon layer. The lower layer 20a is doped with the same doping material as that of the first doping region 20. The upper layer 30a may be formed of the same material as that of the second doping region 30. The upper layer 30a may be doped with the same doping material as that of the second doping region 30.
Since the second diaphragm 34 includes the lower layer 20a, which is formed of the same material and has the same doping characteristics as those of the first doping region 20, when the second diaphragm 34 contacts the first doping region 20 while the energy conversion device operates, a PN junction capacitor is instantly formed, thereby obtaining a relatively high capacitance. The second sealing layer 50 formed on the third doping region 40 covers the fourth through seventh doping regions 42, 44, 46, and 48. A plurality of contact holes are formed in the second sealing layer 50. The sixth doping region 46 and the seventh doping region 48 are exposed through the plurality of contact holes. A top surface of the third doping region 40 between the plurality of through-holes 52 and the fifth doping region 44 adjacent to the sixth doping region 46 is exposed through one of the plurality of contact holes.
First through third electrodes 80, 82, and 84 that are spaced apart from one another are disposed on the second sealing layer 50. The first electrode 80 contacts the seventh doping region 48 through one of the plurality of contact holes. A voltage may be applied to the energy conversion device through the first electrode 80. The second electrode 82 contacts the third doping region 40 through one of the plurality of contact holes. A predetermined voltage or a specific external signal may be applied to the energy conversion device through the second electrode 82. The third electrode 84 contacts the sixth doping region 46 through one of the plurality of contact holes. A voltage, for example, a boosted voltage, output from the energy conversion device may be output to the outside through the third electrode 84.
In
An operation of the energy conversion device of
The input voltage Vin is applied and the capacitor Cm is charged. When a capacitance of the capacitor Cm is a maximum capacitance and charge is constant, the voltage Vc is increased in proportion to a change rate of the capacitance of the capacitor Cm according to a vibration of the vibrator 32+34. In this case, the first diode D1 is reverse biased to the voltage Vc and the second diode D2 is forward biased to the voltage Vc. Accordingly, the capacitor Cload is charged by charges of the capacitor Cm through the second diode D2, to have a potential of the voltage V. Such an event continuously occurs while the vibrator 32+34 vibrates and the capacitance of the capacitor Cm changes between a maximum value and a minimum value. Accordingly, if the vibrator 32+34 vibrates faster than a time constant of a circuit, the direct current (DC) output voltage Vout having a ripple but higher than the input voltage Vin may be obtained. The output voltage Vout may be defined by:
V
out
=[C
m(max)/Cm(min)]Vin (Equation 1).
In Equation 1, Cm(max) denotes the maximum capacitance of the capacitor Cm, and Cm(min) denotes a minimum capacitance of the capacitor Cm.
A capacitance of a general capacitor is proportional to an area of electrodes constituting the general capacitor and is inversely proportional to an interval between the electrodes. Accordingly, when a gap between the second diaphragm 34 and the first doping region 20 is maximized, the capacitance of the capacitor Cm is minimized.
A time when the capacitance of the capacitor Cm is maximized is when the second diaphragm 34 contacts the first doping region 20 as shown in
As shown in
Referring to
Referring to
Referring to
Referring to
The third mask M3 exposes a portion of the top surface of the second silicon layer 300 corresponding to the first oxidized region 70a. As shown in
Referring to
Referring to
When the fourth mask M4 is formed, oxygen ions 76 are implanted into the top surface of the third silicon layer 400. The oxygen ions 76 reach the second silicon layer 300 through the exposed portion of the top surface of the third silicon layer 400, and the oxygen ions 76 are implanted into the portion of the second silicon layer 300 formed over the third oxidized region 74a. The oxygen ions 76 may reach the portion of the second silicon layer 300 formed over the third oxidized region 74a by adjusting ion implantation energy of the oxygen ions 76. After the oxygen ions 76 are implanted, the fourth mask M4 is removed. Next, a resultant structure obtained after the oxygen ions 76 are implanted is annealed. Accordingly, fourth oxidized regions 76a are formed in/of the portion of the second silicon layer 300 formed over the third oxidized region 74a. The fourth oxidized regions 76a may be formed perpendicularly to the third oxidized region 74a. The fourth oxidized regions 76a may be formed at two places to be symmetric about the center of the third oxidized region 74a. The fourth oxidized regions 76a are connected to the third oxidized region 74a. Although the fourth oxidized regions 76a are formed in the second silicon layer 300, the fourth oxidized regions 76a may extend to the top surface of the second silicon layer 300 to contact the third silicon layer 400. The fourth oxidized regions 76a may be formed before the third silicon layer 400 is formed.
Referring to
Referring to
Referring to
Referring to
Referring to
While the resultant structure of
Referring to
Referring to
A method of driving an energy conversion device according to an embodiment will now be explained. From the explanation, it is understood that the energy conversion device may be used for various purposes.
Referring to
Referring to
V
out(t)=[Cm(t)/Cm(min)]Vin (Equation 2).
Referring to
V
out(t)=Qfix/C(t) (Equation 3).
In Equation 3, Qfix denotes fixed charges generated in the dielectric layer 90.
The energy conversion device according to one or more embodiments has a monolithic single-crystal 3D structure. Accordingly, since there is no contact surface or interface between elements constituting the energy conversion device, the energy conversion device may have higher reliability than a related art energy conversion device.
Also, since all elements of the energy conversion device are formed on a single substrate (a single-crystal silicon substrate), material costs may be reduced. Since a method of manufacturing the energy conversion device according to one or more embodiments involves simply repeatedly performing epitaxial growth, doping, ion implantation, and annealing, an overall process may be simplified and used equipment may be simplified. Since the epitaxial growth, the doping, the ion implantation, and the annealing are processes used in a complementary metal-oxide-semiconductor (CMOS) process, the CMOS process may be used.
Also, the energy conversion device may be used for various purposes according to an input signal and ambient physical conditions.
In particular, when the energy conversion device is used as a boost converter, since a PN junction capacitance and a mechanical capacitance are connected and thus a high capacitance ratio is obtained, the energy conversion device may be used as a DC boost converter having a relatively high gain.
While exemplary embodiments have been particularly shown and described above, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Number | Date | Country | Kind |
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10-2011-0085819 | Aug 2011 | KR | national |