A kind of low turn-on voltage diode
Technical field
The invention belongs to technical field of semiconductor device, relate to low turn-on voltage diode.
Background technology
In electronic applications, diode is one of the most frequently used base electronic components and parts.PN junction diode and Schottky diode are two main quasi-tradition rectifier diodes.Wherein PN junction diode cut-in voltage is bigger, but good stability can work in high voltage, is that minority carrier devices and leakage current are less, but because few sub-storage effect makes that the device turn-off time is longer, turn-off power loss is bigger.
Schottky diode do not utilize P type semiconductor to contact with N type semiconductor and forms the PN junction principles, but utilizes metal to contact the metal-semiconductor junction principles of formation with semiconductor, so the forward cut-in voltage is less.Because be the majority carrier conduction, so forward current is bigger, but reverse leakage current is also bigger.The not few sub-storage effect of Schottky diode so turn-off power loss is minimum, can be applied to high frequency situations simultaneously.
In order to improve diode behavior; The PiN diode has been proposed both at home and abroad; Junction Barrier Controlled rectifier JBS (JBS:Junction Barrier Schottky Rectifier); Mix PiN/ Schottky rectifier MPS (MPS:Merged P-i-N/Schottky Rectifier), MOS control diode MCD devices such as (MCD:MOS Controlled Diode).Between P type and N type semiconductor material, add the low-doped intrinsic semiconductor layer of thin layer, the diode of this P-i-N structure of composition is exactly the PiN diode.When for the PiN diode forward voltage being provided, the charge carrier in P district and N district is injected into the intrinsic region simultaneously.But because the doping content of intrinsic region is lower, be easy to when adding positive voltage, form big injection, it is compound in a large number that a large amount of electronics in intrinsic region and hole can not be carried out as the PN junction diode, can postpone a period of time usually.Because this delay phenomenon, the resistivity of insulation layer will be very low.The intrinsic region also can help device well withstand voltage, but more unfavorable when a large amount of few son in intrinsic region turn-offs for device, and the few son that oppositely extracts the intrinsic region can influence the frequency characteristic of device and increase turn-off power loss.
Junction barrier schottky JBS (JBS:Junction Barrier Schottky Rectifier) structure and the proposition that mixes PiN/ Schottky rectifier MPS (MPS:Merged P-i-N/Schottky Rectifier) structure make PN junction combined with the advantage of Schottky junction structure.Wherein utilizing the lower advantage of Schottky diode cut-in voltage during the JBS forward, make device about 0.3V, just can open, is the majority carrier conduction during forward simultaneously, makes that the device forward current is big, and conduction loss descends.Utilize the characteristic of PN junction diode when reverse, make device reverse withstand voltage better than Schottky with the reverse leakage properties of flow.
Summary of the invention
In order to reduce the forward cut-in voltage better, improve the device forward current and to reduce the break-over of device power consumption, the present invention provides a kind of low turn-on voltage diode, and it has anode ohmic contact, Schottky junction structure and junction field tubular construction.The introducing of junction field tubular construction makes the device cut-in voltage very low, makes device have high breakdown voltage and less leakage current.Because positive anode ohmic contact and Schottky junction structure can improve the forward current of device, this diode can obtain low-down conduction voltage drop.The depletion region of anode Schottky junction structure has quickened the pinch off of the conducting channel of semiconductor surface under reverse voltage, also helps to reduce device creepage,
Technical scheme of the present invention is following:
A kind of low turn-on voltage diode, its basic structure is as shown in Figure 1, comprises N
+Substrate 2, be positioned at N
+The metallization negative electrode 1 at substrate 2 back sides be positioned at N
+The N in substrate 2 fronts
-Epitaxial loayer 3; N
-Epitaxial loayer 3 surfaces are metallization anodes 8, N
-Both sides, epitaxial loayer 3 top have 6, two P types of P type heavily doped region heavily doped region, 6 next doors respectively and have a N type heavily doped region 7 respectively; Metallization anode 8 is positioned at the device top layer, covers all P type heavily doped regions 6, N type heavily doped region 7 and N
-The surface of epitaxial loayer 3; Two P type heavily doped region 6 belows also have 5, two dark P tagma, a dark P tagma 5 respectively and link to each other with metallization anode 8 through a P type heavily doped region 6 respectively; The lateral dimension in dark P tagma 5 is greater than the lateral dimension of P type heavily doped region 6, two dark P tagmas 5 and the N between them
-Epitaxial loayer 3 constitutes a junction field effect transistor district 4.
Operation principle of the present invention:
When a kind of low turn-on voltage diode provided by the present invention, the length in junction field area under control are big, add current path of the middle generation of depletion region that less positive voltage just can make the technotron district at anode.The anode ohmic contact makes device have only to want current path just can between anode and negative electrode, produce electric current, even anode institute making alive also is not enough to open schottky junction and PN junction produces the big electric current of forward.The introducing of junction field tubular construction makes that conducting channel is by pinch off under very little reverse voltage, and the reverse voltage of increase is mainly born by low-doped epitaxial loayer, greatly reduces leakage current and has improved puncture voltage.The depletion region of Schottky junction structure has quickened the pinch off of semiconductor surface conducting channel under reverse voltage, has realized the lifting of devices switch characteristic better.Be example now, operation principle of the present invention is described with Fig. 1.
A kind of low turn-on voltage diode provided by the present invention is when metallization anode 8 adds no-voltage with respect to metallization negative electrode 1, because the doping content in dark P tagma 5 is far longer than N
-The doping content of epitaxial loayer 3, dark P tagma 5 and N
-The depletion region of the PN junction that epitaxial loayer 3 forms is to 3 expansions of N-epitaxial loayer, makes the N in junction field area under control 4
-Epitaxial loayer 3 is in spent condition; When metallization anode 8 with respect to metallization negative electrode 1 when adding very little forward voltage, positive voltage is received through P type heavily doped region 6 and metallization anode 8 in the dark P tagma 5 in junction field effect transistor district 4, makes dark P tagma 5 and N
-The depletion region of the PN junction that epitaxial loayer 3 forms dwindles the N in junction field effect transistor district 4
-Epitaxial loayer 3 conducting channels are opened, and raceway groove forms conductive path with N type heavily doped region 7 in device, thus the diode forward conducting.When metallization anode 8 added reverse voltage with respect to metallization negative electrode 1, the conducting channel in junction field area under control 4 was continued to increase reverse voltage by pinch off, and depletion layer is to the N near metallization negative electrode 1 one sides
-Epitaxial loayer 3 expansions, thus make diode structure of the present invention can bear very high reverse breakdown voltage, and surface metalation anode 8 and N
-The depletion region of the Schottky junction structure that epitaxial loayer 3 forms makes leakage current smaller.
By the MEDICI simulation software a kind of low turn-on voltage diode as shown in Figure 1 that is provided has been carried out emulation.The emulation device parameters is: dark P tagma doping content is 3 * 10
17Cm
-3, thickness is 0.65 μ m; N
-Epitaxial loayer mixes 3.4 * 10
15Cm
-3, thickness is 9.5 μ m; N type heavily doped region mixes 8 * 10
19Cm
-3, P type heavily doped region mixes 1.8 * 10
20Cm
-3, N type substrate zone mixes 1 * 10
20Cm
-3, emulation cellular width is 2 μ m, and dark P tagma spacing is 0.8um, and the surface metal work function is 4.8eV.
Fig. 2 is the forward conduction voltage drop simulation curve of above-mentioned a kind of low turn-on voltage diode.Can know that by figure approximately the forward voltage of 0.2V just can make the N between the dark P tagma
-Epitaxial loayer is opened current channel.Simultaneously because the anode surface ohmic contact is communicated with the current channel between the P tagma deeply, making just has bigger forward current under less forward voltage.
Fig. 3 is the puncture voltage simulation curve figure of above-mentioned a kind of low turn-on voltage diode.Dark P tagma and N
-The PN junction that epitaxial loayer forms bears puncture voltage, and depletion region is to N
-The epitaxial loayer expansion.Can be known that by figure the depletion region between the dark P tagma has reduced leakage current, the depletion region of anode Schottky structure formation simultaneously also greatly reduces the leakage current of device.
In sum, a kind of low turn-on voltage diode provided by the invention, owing to combined PN junction, ohmic contact and Schottky junction structure also improved forward current greatly when reducing cut-in voltage, and reverse leakage current have also obtained reduction.
Description of drawings
Fig. 1 is a kind of low turn-on voltage diode structural representation provided by the invention
Wherein, the 1st, metallization negative electrode, the 2nd, N
+Substrate zone, the 3rd, N
-Epitaxial loayer, the 4th, junction field effect transistor district, the 5th, dark P tagma, the 6th, P type heavily doped region, the 7th, N type heavily doped region, the 8th, metallization anode.
Fig. 2 is the forward conduction voltage drop simulation curve figure of a kind of low turn-on voltage diode provided by the present invention.
Fig. 3 is the reverse breakdown voltage simulation curve figure of a kind of low turn-on voltage diode provided by the present invention.
Embodiment
Adopt a kind of low turn-on voltage diode of the present invention, can realize less forward cut-in voltage, low conduction voltage drop, high reverse breakdown voltage, less reverse leakage current, good reverse recovery characteristic.Along with development of semiconductor, adopt the present invention can also make more high voltage low power consumption device.
A kind of low turn-on voltage diode, its basic structure is as shown in Figure 1, comprises N
+Substrate 2, be positioned at N
+The metallization negative electrode 1 at substrate 2 back sides be positioned at N
+The N in substrate 2 fronts
-Epitaxial loayer 3; N
-Epitaxial loayer 3 surfaces are metallization anodes 8, N
-Both sides, epitaxial loayer 3 top have 6, two P types of P type heavily doped region heavily doped region, 6 next doors respectively and have a N type heavily doped region 7 respectively; Metallization anode 8 is positioned at the device top layer, covers all P type heavily doped regions 6, N type heavily doped region 7 and N
-The surface of epitaxial loayer 3; Two P type heavily doped region 6 belows also have 5, two dark P tagma, a dark P tagma 5 respectively and link to each other with metallization anode 8 through a P type heavily doped region 6 respectively; The lateral dimension in dark P tagma 5 is greater than the lateral dimension of P type heavily doped region 6, two dark P tagmas 5 and the N between them
-Epitaxial loayer 3 constitutes a junction field effect transistor district 4.
In the such scheme: 1, do not have overlapping region between said N type heavily doped region 7 and the dark P tagma 5; 2, metallization negative electrode 7 and metallization anode 8 can adopt aluminium, copper, tungsten or other metallic conduction material; 3, the device semiconductor material can adopt semi-conducting material manufacturings such as body silicon, carborundum, GaAs, indium phosphide or germanium silicon.。
A kind of low turn-on voltage diode, its concrete implementation method comprises: choose the N type<100>Crystal orientation zone melting single-crystal substrate, N
-Outer layer growth, dark P tagma boron inject, and P type heavily doped region boron injects, and N type heavily doped region arsenic injects, etching ohm hole, front-side metallization, metal etch, back face metalization, passivation or the like.