CN100454582C - Semiconductor device - Google Patents
Semiconductor device Download PDFInfo
- Publication number
- CN100454582C CN100454582C CNB2006100738016A CN200610073801A CN100454582C CN 100454582 C CN100454582 C CN 100454582C CN B2006100738016 A CNB2006100738016 A CN B2006100738016A CN 200610073801 A CN200610073801 A CN 200610073801A CN 100454582 C CN100454582 C CN 100454582C
- Authority
- CN
- China
- Prior art keywords
- layer
- diffusion layer
- type diffused
- diffused layer
- anode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Electrodes Of Semiconductors (AREA)
Abstract
In a semiconductor device of the present invention, a protection diode for protecting a device is formed on an epitaxial layer formed on a substrate. A Schottky barrier metal layer is formed on a surface of the epitaxial layer and a P-type diffusion layer is formed at a lower portion of an end portion of the Schottky barrier metal layer. Then, a P-type diffusion layer is formed to be connected to a P-type diffusion layer and is extended to a cathode region. A metal layer to which an anode electrode is applied is formed above the P-type diffusion layer, thereby making it possible to obtain a field plate effect. This structure reduces a large change in a curvature of a depletion layer, thereby improving a withstand voltage characteristic of the protection diode.
Description
Technical field
The present invention relates to the semiconductor device that the protective circuit element is not destroyed by overvoltage.
Background technology
In existing semiconductor devices, on the N type semiconductor substrate, be formed with N type epitaxial loayer.On the n type diffused layer that is formed on the epitaxial loayer, overlapped to form p type diffused layer.And, on p type diffused layer, form anode electrode, and form cathode electrode at substrate back, utilize the PN junction of two diffusion layers and constitute Zener diode.Periphery at p type diffused layer is formed with P type protection zone, is formed with another protection zone in its outside in addition.And, be formed with the Schottky barrier metal level contiguously with the epitaxial loayer that surrounds by two protection zones.Constitute Schottky barrier diode by Schottky barrier with the silicide and the epitaxial loayer of metal level.In existing semiconductor devices, Zener diode is connected side by side with Schottky barrier diode, can reduce the forward voltage (Vf) (for example, with reference to patent documentation 1) of element self.
In existing semiconductor devices, be formed with the high p type diffused layer of impurity concentration on the surface in N type semiconductor zone, and between this diffusion layer, be formed with the low p type diffused layer of impurity concentration.Be formed at the electrode and the high p type diffused layer ohmic contact of impurity concentration on the surface in N type semiconductor zone, and and the low p type diffused layer of impurity concentration between form Schottky barrier.Be formed with the Zener diode that uses PN junction in the formation zone of the high p type diffused layer of impurity concentration.On the other hand, form the zone at the low p type diffused layer of impurity concentration and be formed with the diode that constitutes by Zener diode and Schottky barrier.By this structure, reduce the free carrier (hole) that injects to the N type semiconductor zone from p type diffused layer, reduce near the free carrier of accumulating the PN junction zone (hole).And, reduce reverse reverting current density (for example, with reference to patent documentation 2).
In existing planar-type semiconductor device, on be formed at the P type semiconductor zone in N type semiconductor zone, be formed with anode electrode.On the N type semiconductor zone, be formed with the conductivity field plate (Off イ one Le De プ レ one ト) that is connected with anode electrode.And the equipotential ring electrode that is formed at above the N type semiconductor zone is connected by the resistive field plate with the conductivity field plate.And, will be positioned at the thickness thickening of dielectric film of the bottom, border of conductivity field plate and resistive field plate, will be positioned at the reduced thickness of dielectric film of the resistive field plate bottom of equipotential ring electrode side.By this structure, strengthen the effect of resistive field plate, reduce the curvature of depletion layer of the bottom, border of conductivity field plate and resistive field plate.And, realized withstand voltage raising (for example, with reference to patent documentation 3) in the zone that electric field is concentrated easily.
Patent documentation 3 spies open flat 8-130317 communique (3-6 page or leaf, Fig. 2,4)
As mentioned above, in existing semiconductor devices, in an element, be connected with Zener diode and Schottky barrier diode side by side.By this structure, forward voltage (Vf) utilizes the characteristic of Schottky barrier diode, can realize low voltage drive.But in Schottky barrier diode, principal current is stream with the epitaxial loayer.Therefore, the dead resistance that has epitaxial loayer is big, can not reduce the problem of ON resistance value.
In addition, in existing semiconductor devices, in Zener diode, be formed with P type protection zone below the anode electrode end on be formed at epitaxial loayer.Equally, in Schottky barrier diode, below the end of Schottky barrier, be formed with P type protection zone with metal level.By this structure, protect by the zone that concentrate easily to electric field P type protection zone.But, in that P type protection zone is configured in the structure of most peripheral, when applying reverse biased, in the anode electrode end or Schottky barrier with the end periphery of metal level, the curvature of depletion layer changes easily.Particularly, in the time of near the terminal area that described end is disposed at depletion layer, it is big that the curvature changing of depletion layer becomes.Its result has and causes easily that in the zone of the curvature changing of depletion layer electric field concentrates, and is difficult to realize the problem of desirable voltage endurance.
In addition, in existing semiconductor devices, when Zener diode moves, exceedingly accumulated as the free carrier (hole) of minority carrier in N type epitaxial loayer zone.And, when Zener diode ends, need this free carrier of accumulating (hole) is got rid of from p type diffused layer.At this moment, near free carrier (hole) concentration the p type diffused layer uprises, and it is big that the absolute value of the time rate of change of reverse reverting electric current (di/dt) becomes.And, exist time rate of change (di/dt) to cause the problem that the protection diode destroys owing to the reverse reverting electric current.
Summary of the invention
The present invention constitutes in view of described problem, and semiconductor device of the present invention is characterized in that, comprising: first and second anode diffusion layer of opposite conductivity type, and it separately forms on the semiconductor layer of a conduction type; The cathode diffusion layer of one conduction type, it is formed on the described semiconductor layer; The third anode diffusion layer of opposite conductivity type, it is connected with described second plate diffusion layer and is formed extended at both sides on described semiconductor layer to described cathode diffusion layer side; Insulating barrier, it is formed on above the described semiconductor layer; Anode electrode, it is connected with described first and second anode diffusion layer via being formed at the contact hole on the described insulating barrier, and engage with the described semiconductor layer Schottky between described first anode diffusion layer and the described second plate diffusion layer, wherein, above the described insulating barrier above described third anode diffusion layer, the metal level that disposes described anode electrode or be connected with described anode electrode.Therefore, in the present invention, because the protection diode carries out ON action (turn-on action) with the forward voltage (Vf) that is lower than circuit element, so can not destroyed by overvoltage by the protective circuit element.In addition, at anode region, the third anode diffusion layer is than the more close cathode diffusion layer side of second plate diffusion layer.According to this structure, can prevent the withstand voltage deterioration of anode electrode end, the protection diode can be kept desirable voltage endurance.
Semiconductor device of the present invention is characterized in that, disposes above the described second plate diffusion layer of described semiconductor layer by offering the end of the described anode electrode that described contact hole forms.Therefore, the present invention can reduce the curvature changing of the depletion layer below the anode electrode end, prevents that electric field is concentrated, and can prevent to protect the withstand voltage deterioration of diode.
Semiconductor device of the present invention is characterized in that, described second plate diffusion layer is made of the diffusion layer of two kinds of different opposite conductivity type of impurity concentration at least.Therefore, in the present invention, can near the end of anode electrode, form the high diffusion layer of impurity concentration.By this structure, can be suppressed at the electric field diffusion of the depletion layer in concentrated zone easily, and prevent to protect the withstand voltage deterioration of diode.
Semiconductor device of the present invention is characterized in that, the impurity concentration of described third anode diffusion layer is lower than the impurity concentration of the diffusion layer of the described opposite conductivity type that constitutes described second plate diffusion layer.Therefore, among the present invention, when the protection diode applies reverse biased, the terminal area of depletion layer is left from the second plate diffusion layer.By this structure, reduce the curvature changing of the terminal area of depletion layer, prevent to protect the withstand voltage deterioration of diode.
Semiconductor device of the present invention is characterized in that, has overlapped to form opposite conductivity type and discharge and to use diffusion layer on described cathode diffusion layer, and be connected with cathode electrode in the discharge of described opposite conductivity type on diffusion layer.Therefore, in the present invention, in protection during diode action, can be via cathode diffusion layer, by again in conjunction with and the free carrier in the semiconductor layer (hole) is eliminated.In addition, via the discharge diffusion layer of the opposite conductivity type that has applied cathode potential, the free carrier in the semiconductor layer (hole) can be discharged.By this structure, can reduce the absolute value of the time rate of change (di/dt) of reverse reverting electric current, prevent to protect diode destroyed.
Semiconductor device of the present invention is characterized in that, described anode electrode or the metal level that is connected with described anode electrode more extend to described cathode electrode side than described third anode diffusion layer.Therefore, in the present invention, anode electrode or the metal level that is connected with anode electrode use as field plate.By this structure, can improve the voltage endurance of protection diode by the field effect effect.
Semiconductor device of the present invention is characterized in that, disposes above described anode electrode to described anode electrode and applies the contact hole that the wiring layer of anode potential is used.Therefore, in the present invention, the anode electrode that can suppress to connect up draw around, dwindle the area of wiring pattern.
In semiconductor device of the present invention, on the described semiconductor layer below the wiring layer that has applied described anode potential, dispose and the idiostatic electric field barrier film of described cathode diffusion layer, described electric field barrier film is configured in the zone that the wiring layer that is applied with described anode potential and described cathode diffusion layer intersect.Therefore, in the present invention, the electric field barrier film has shield effectiveness for the wiring layer that is applied with anode potential, can prevent the cathode zone counter-rotating, the situation that anode region and area of isolation are short-circuited.
Among the present invention, on semiconductor layer, be formed with protection diode with Zener diode and Schottky barrier diode configuration arranged side by side.The protection diode utilizes low forward voltage (Vf) characteristic of Schottky barrier diode.And the protection diode is connected side by side with the desired circuit element.By this structure, when circuit element was applied with overvoltage, the protection diode can prevent that than the first action of circuit element circuit element is destroyed.
In addition, among the present invention, below the end of Schottky barrier, be formed with p type diffused layer with metal level.And p type diffused layer that impurity concentration is low and described p type diffused layer link and extend to the cathode zone side.By this structure, when on the protection diode, having applied reverse biased, can reduce the curvature changing of the terminal area of depletion layer, voltage endurance is improved.
Among the present invention, below the end of anode electrode, be formed with the high diffusion layer of impurity concentration of dual diffusion structure.By this structure, can prevent that depletion layer from extending near the end of anode electrode, prevent that the electric field in its zone from concentrating.And, can prevent to protect the withstand voltage deterioration of diode.
Among the present invention, be formed with the p type diffused layer that has applied cathode potential at cathode zone.By this structure, when the protection diode action, can reduce the concentration of the free carrier (hole) in the semiconductor layer.And, can reduce the absolute value of the time rate of change (di/dt) of reverse reverting electric current, prevent to protect diode destroyed.
Among the present invention, on the anode diffusion layer that extends to cathode electrode side, be formed with the metal level or the anode electrode that have applied anode potential.By this structure, when the protection diode has applied reverse biased, can obtain the field plate effect, reduce the curvature changing of depletion layer, voltage endurance is improved.
Description of drawings
Fig. 1 (A), (B) are the profiles of the protection diode of explanation embodiment of the present invention;
Fig. 2 (A), (B) are the profiles of the Zener diode of explanation embodiment of the present invention;
Fig. 3 is the figure of the forward voltage (Vf) of explanation protection diode of embodiment of the present invention and Zener diode;
Fig. 4 is the figure that the circuit of the protection diode that is assembled with embodiment of the present invention is described;
Fig. 5 (A) is the figure of Potential distribution of reverse bias condition of the protection diode of explanation embodiment of the present invention, (B) is the figure of ionization by collision generation area of the protection diode of explanation embodiment of the present invention;
Fig. 6 is the figure of Potential distribution of reverse bias condition of the protection diode of explanation embodiment of the present invention;
Fig. 7 is the figure of CONCENTRATION DISTRIBUTION of the free carrier (hole) of explanation protection diode of embodiment of the present invention and Zener diode;
Fig. 8 is the plane graph of the protection diode of explanation embodiment of the present invention.
Symbol description
1 protection diode
2 p type single crystal silicon substrates
3 N type epitaxial loayers
5 p type diffused layers
7 p type diffused layers
8 p type diffused layers
10 n type diffused layers
13 p type diffused layers
14 Schottky barrier metal levels
18 metal levels
20 ends
21 silicide layers
Embodiment
Below, with reference to accompanying drawing 1～7, describe an execution mode of semiconductor device of the present invention in detail.Fig. 1 (A) and (B) be the profile that is used to illustrate the protection diode of present embodiment.Fig. 2 (A) and (B) be the profile that is used to illustrate the Zener diode of present embodiment.Fig. 3 is the figure of the forward voltage (Vf) of explanation protection diode of present embodiment and Zener diode.Fig. 4 is the figure that the circuit of the protection diode that is assembled with present embodiment is described.Fig. 5 (A) is the protection diode about present embodiment, and the figure of the Potential distribution of reverse bias condition is described.Fig. 5 (B) is the figure of ionization by collision generation area on the protection diode of explanation present embodiment.Fig. 6 is the protection diode about present embodiment, and the figure of the Potential distribution of reverse bias condition is described.Fig. 7 is the figure of CONCENTRATION DISTRIBUTION of the free carrier (hole) of explanation protection diode of present embodiment and Zener diode.Fig. 8 is the profile that is used to illustrate the protection diode of present embodiment.
Shown in Fig. 1 (A), the primary structure of Zener diode and the Schottky barrier diode protection diode 1 that disposes arranged side by side is as follows: p type single crystal silicon substrate 2; N type epitaxial loayer 3; The N type is imbedded diffusion layer 4; Be used as the p type diffused layer 5,6,7,8,9 of anode region; Be used as the n type diffused layer 10,11 of cathode zone; P type diffused layer 12,13; Be used as the Schottky barrier metal level 14 of anode electrode; Be used as the metal level 15 of cathode electrode; Insulating barrier 16,17; The metal level 18 that is connected with anode electrode.
N type epitaxial loayer 3 is deposited in above the p type single crystal silicon substrate 2.In addition, the epitaxial loayer in the present embodiment 3 is corresponding to " semiconductor layer " of the present invention.And, represented on substrate 2, to be formed with the situation of one deck epitaxial loayer 3 in the present embodiment, but the invention is not restricted to this.For example, as " semiconductor layer " of the present invention, also can be the situation that lamination has a plurality of epitaxial loayers on substrate.In addition, as " semiconductor layer " of the present invention, can only be substrate also, and, also can be n type single crystal silicon substrate, compound semiconductor substrate as substrate.
The N type is imbedded diffusion layer 4 and is formed on substrate 2 and epitaxial loayer 3 these two zones.As shown in the figure, the N type is imbedded on the formation zone that diffusion layer 4 is formed on the protection diode of being divided by area of isolation 19 1.
P type diffused layer 5,6 is formed on the epitaxial loayer 3.P type diffused layer 5 is 1.0E16～17 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 5～6 (μ m) forms.P type diffused layer 6 is 1.0E19～20 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 1～3 (μ m) forms.And p type diffused layer 5 forms and carries out the PN junction zone that PN engages with N type epitaxial loayer 3, and p type diffused layer 5,6 is used as the anode region of Zener diode.In addition, the p type diffused layer 5,6 corresponding " first anode diffusion layer of opposite conductivity type " of the present invention of present embodiment.But,, also can only be p type diffused layer 5 or p type diffused layer 6 as " first anode diffusion layer of opposite conductivity type " of the present invention.And also can for example forming on p type diffused layer 5,6, its surface impurity concentration be 1.0E17～18 (/cm
2) about, diffusion depth is the p type diffused layer about 2～4 (μ m), forms triple diffusion structure.
P type diffused layer 7,8 on epitaxial loayer 3, surround p type diffused layer 5 around and form a ring-type.P type diffused layer 7 is 1.0E16～17 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 5～6 (μ m) forms.P type diffused layer 8 is 1.0E17～18 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 2～4 (μ m) forms.P type diffused layer 7 forms and carries out the PN junction zone that PN engages with N type epitaxial loayer 3, and p type diffused layer 7,8 is used as the anode region of Zener diode.In addition, p type diffused layer 7,8 is formed on 20 belows, end that the Schottky barrier that becomes anode electrode is used metal level 14.The p type diffused layer 8 higher than the impurity concentration of p type diffused layer 7 overlaps to form with p type diffused layer 7.In addition, the p type diffused layer 7,8 corresponding " the second plate diffusion layer of opposite conductivity type " of the present invention of present embodiment.But, as " the second plate diffusion layer of opposite conductivity type " of the present invention, also can only be p type diffused layer 7 or p type diffused layer 8, in addition, can also be MULTIPLE DIFFUSION structures such as triple diffusion structure.
P type diffused layer 9 surround p type diffused layers 5 around and form a ring-type, it is overlapping with p type diffused layer 7,8 that its part forms the zone.P type diffused layer 9 is 1.0E15～16 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 1～3 (μ m) forms.And p type diffused layer 9 more extends to n type diffused layer 10 sides than p type diffused layer 7,8.The impurity concentration of p type diffused layer 9 is lower than the impurity concentration of p type diffused layer 7,8.In addition, the p type diffused layer 9 corresponding " the third anode diffusion layer of opposite conductivity type " of the present invention of present embodiment.
N type diffused layer 10,11 on epitaxial loayer 3, surround p type diffused layer 5 around and form a ring-type.N type diffused layer 10,11 and N type epitaxial loayer 3 are used as the cathode zone of Zener diode and Schottky barrier diode.And n type diffused layer 10 reduces parasitic resistance values by forming wide diffusion zone.On the other hand, n type diffused layer 11 is narrow diffusion zones, but can realize low resistanceization by forming the high zone of impurity concentration.In addition, the n type diffused layer 10,11 corresponding " cathode diffusion layer of a conduction type " of the present invention of present embodiment.But, as " cathode diffusion layer of a conduction type " of the present invention, also can only be n type diffused layer 10 or n type diffused layer 11, in addition, can also be MULTIPLE DIFFUSION structures such as triple diffusion structure.
The formation region overlapping of p type diffused layer 12,13 is on n type diffused layer 10.P type diffused layer 12,13 surround p type diffused layers 5 around and form a ring-type.P type diffused layer 12 is 1.0E16～17 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 5～6 (μ m) forms.And p type diffused layer 13 is 1.0E19～20 (/cm by for example its surface impurity concentration
2) about, diffusion depth is that diffusion conditions about 1～3 (μ m) forms.N type diffused layer 11 contacts with the metal level 15 that uses as cathode electrode with p type diffused layer 13.By this structure, p type diffused layer 12,13 and n type diffused layer 10,11 become idiostatic.In addition, the p type diffused layer 12,13 corresponding " the discharge diffusion layer of opposite conductivity type " of the present invention of present embodiment.But, as " the discharge diffusion layer of opposite conductivity type " of the present invention, also can only be p type diffused layer 12 or p type diffused layer 13, in addition, can also be MULTIPLE DIFFUSION structures such as triple diffusion structure.
Schottky barrier is formed on above the epitaxial loayer 3 with metal level 14.Schottky barrier is for example piled up titanium nitride (TiN) layer with metal level 14 on titanium (Ti) layer.Shown in thick line,, be formed with Titanium silicide (TiSi on the surface of the epitaxial loayer 3 between p type diffused layer 5 and the p type diffused layer 7
2) layer be silicide layer 21.And, constitute Schottky barrier diode with the silicide layer 21 and the epitaxial loayer 3 of metal level 14 by Schottky barrier.In addition, also can replace titanium (Ti) layer and use tungsten (W), molybdenum (Mo), tantalum (Ta), cobalt (Co), nickel (Ni), platinum metals such as (Pt).At this moment, as silicide layer 20, be formed with tungsten silicide (WSi
2) layer, molybdenum silicide (MoSi
2) layer, cobalt silicide (CoSi
2) layer, nickel silicide (NiSi
2) layer, platinum silicide (PtSi
2) layer etc.
Insulating barrier 16,17 is formed on epitaxial loayer 3 tops. Insulating barrier 16,17 is optionally lamination silicon oxide layer, silicon nitride film, TEOS (Tetra-Ethyl-Orso-Silicate) film, BPSG (BoronPhosPho Silicate Glass) film, SOG (SPin On Glass) film etc. and form for example.On insulating barrier 16, be formed with contact hole 22.Contact hole 22 is buried underground with metal level 14 by Schottky barrier, and Schottky barrier is used as anode electrode with metal level 14.In addition, the insulating barrier 16,17 corresponding " insulating barrier " of the present invention of present embodiment.But, as " insulating barrier " of the present invention, so long as optionally lamination the film of described silicon oxide layer etc. get final product.
In addition, in the present embodiment, shown in Fig. 1 (B), Schottky barrier with metal level 14 also can be shown in Fig. 1 (A) metal level 18 such, cover the top, formation zone of p type diffused layer 9 and form.In this case, when protection diode 1 has applied reverse biased, Schottky barrier uses as field plate with metal level 14, and the voltage endurance of protection diode 1 is improved.
Expression Zener diode 31 among Fig. 2 (A).In addition, Zener diode 31 is the structures that have with the roughly the same voltage endurance of protection diode shown in Figure 11.Below, its structure is described.
N type epitaxial loayer 33 is deposited in above the p type single crystal silicon substrate 32.The N type is imbedded diffusion layer 34 and is formed on substrate 32 and epitaxial loayer 33 these two zones.P type diffused layer 35,36,37 is formed on the epitaxial loayer 33.P type diffused layer 35,36 forms and carries out the PN junction zone that PN engages with N type epitaxial loayer 33, and p type diffused layer 35,36,37 is used as the anode region of Zener diode.
N type diffused layer 38,39 is formed on the epitaxial loayer 33.The cathode zone that n type diffused layer 38,39 and N type epitaxial loayer 33 are used as Zener diode uses.And p type diffused layer 40,41 is formed on the n type diffused layer 38.
Insulating barrier 42 is formed on above the epitaxial loayer 33, is formed with contact hole 43,44 on insulating barrier 42.Metal level 45 is connected with p type diffused layer 37 via contact hole 43, and is used as anode electrode.Metal level 46 is connected with n type diffused layer 39, p type diffused layer 41 via contact hole 44, and is used as cathode electrode.
Insulating barrier 47 is formed on the insulating barrier 42, is formed with contact hole 48 on insulating barrier 47.Metal level 49 is connected with metal level 45 via contact hole 48.In addition, metal level 49 covers the top, formation zone of p type diffused layer 36 and forms, and has the field plate effect.
In addition, in the present embodiment, shown in Fig. 2 (B), the metal level 49 of metal level 45 shown in Fig. 2 (A) is such, covers the top, formation zone of p type diffused layer 36 and forms.
Then, in Fig. 3, represent to protect the forward voltage (Vf) of diode 1, dot the forward voltage (Vf) of PN diode 31 with solid line.
Such described with reference to Figure 1, on protection diode 1, dispose PN diode and Schottky barrier diode side by side.According to this structure, for example when Vf is less than or equal to 0.8 (V), protection diode 1 is bigger than the forward current (If) of PN diode 31 as can be known, and current capacity is good.On the other hand, when If was 1.0E-8 (A), protection diode 1 drove with the current potential that is lower than PN diode 31.That is to say; is connected side by side with protection diode 1 by the MOS transistor that is connected with lead-out terminal according to this element characteristic etc., thereby can protect MOS transistor etc. for example not to be subjected between cathode ray tube (Block ラ ウ Application) discharge the time or the destruction of the overvoltage of generation when disconnecting such as the L load of motor load etc. etc.
Specifically, the circuit that is expressed as follows among Fig. 4, that is, between power line (Vcc) and ground connection (GND), be connected in series N channel type MOS transistor X, Y, and the drain electrode of the source electrode of MOS transistor X and MOS transistor Y is connected with lead-out terminal.
At this, illustrate on the lead-out terminal of the circuit that be not connected with protection diode 1 between power line (Vcc) and the lead-out terminal to have applied superpotential situation.Between source electrode-drain electrode of the MOS transistor X of the state that is applied with reverse biased, apply forward bias voltage drop by overvoltage.At this moment, flow through the electric current more than or equal to feasible value between source electrode-drain electrode, the PN junction zone is destroyed, and MOS transistor X is destroyed.
But, in the present embodiment, between power line (Vcc) and lead-out terminal, be connected with protection diode 1 and MOS transistor X side by side.At this moment, such described with reference to Figure 3, if apply overvoltage, then protect diode 1 action earlier to lead-out terminal, can make the most of electric current that causes by overvoltage flow to power line (Vcc) by protection diode 1.Its result, the electric current that will flow through between source electrode-drain electrode of MOS transistor X owing to overvoltage reduces, and can prevent the destruction in PN junction zone.
Then, in Fig. 5 (A), heavy line is represented the end regions of depletion layer, and dotted line is represented equipotential line, and chain-dotted line is represented the equipotential line of 318 (V).With below the end 20 of metal level 14, p type diffused layer 7,8 forms dual diffusion structure at Schottky barrier.And p type diffused layer 7,8 overlapping areas are the high impurity concentration zone, represent as solid line, have the zone of not exhausting.Its result, below Schottky barrier usefulness metal level 14, the interval of equipotential line is narrowless, becomes to be difficult to take place the state that electric field is concentrated.That is to say, relaxed at Schottky barrier and concentrated, can improve the voltage endurance of protection diode 1 with the electric field of end 20 generations of metal level 14.
In addition, p type diffused layer 9 links with p type diffused layer 7,8, and p type diffused layer 7 extends to cathode electrode side.The impurity concentration of p type diffused layer 9 is low, and as shown in the figure, depleted layer is full of.And in the zone that p type diffused layer 9 forms, pass lentamente at the interval of equipotential line.That is to say that the p type diffused layer 9 that depleted layer is full of is configured in the most peripheral of anode electrode.By this structure, as shown in the figure, reduce curvature changing in the terminal area of depletion layer, improve the voltage endurance of protection diode 1.Its result can improve the problem of the withstand voltage deterioration that causes owing to the formation Schottky barrier diode, and can realize the low forward driving of voltage (Vf) based on Schottky barrier diode.
Represent the Potential distribution when under the reverse bias condition of Fig. 5 (A), being altered to the position of the end 24 of metal level 18 above the p type diffused layer 9 among Fig. 6.Heavy line is represented the end regions of depletion layer, and dotted line is represented equipotential line, and chain-dotted line is represented the equipotential line of 279 (V).As shown in the figure, the field plate effect of the metal level 18 by having applied anode electrode, the part of equipotential line converges and displacement to the end 24 of metal level 18.At this moment, the position anode electrode side of the end 24 by making metal level 18 changes, and has suppressed the expansion of depletion layer.As a result, compare with the situation of Fig. 5 (A), the voltage endurance of protection diode worsens.
In addition, in the present embodiment, the metal level 18 that works as field plate more is illustrated to the situation that cathode electrode side is extended than p type diffused layer 9.But the invention is not restricted to this.Can be according to the thickness of the insulating barrier of impurity concentration, diffusion depth and metal level 18 belows of p type diffused layer 9 etc., change the position relation of end 24 with the end 25 of p type diffused layer 9 of metal level 18 arbitrarily.For example, under the identical condition of the thickness of the diffusion depth of p type diffused layer 9 and the insulating barrier below the metal level 18, the impurity concentration situation higher than present embodiment of p type diffused layer 9 arranged.At this moment, form the structure that more extend to cathode electrode side than the end 25 of p type diffused layer 9 end 24 of metal level 18.By this structure, the electric field influence from metal level 18 can be strengthened, improve the voltage endurance of protection diode 1.The impurity concentration situation lower that p type diffused layer 9 is arranged on the other hand, than present embodiment.At this moment, form the structure that more extend to cathode electrode side than the end 24 of metal level 18 end 25 of p type diffused layer 9.By this structure, the electric field influence from metal level 18 can be weakened, improve the voltage endurance of protection diode 1.
Then; among Fig. 7; solid line represents to protect the CONCENTRATION DISTRIBUTION of the free carrier (hole) in the A-A section (with reference to Fig. 1 (A)) of diode 1, and dotted line is represented the CONCENTRATION DISTRIBUTION of the free carrier (hole) in the B-B section (with reference to Fig. 2 (A)) of Zener diode 31.In addition, the longitudinal axis is represented the concentration of the free carrier (hole) in the epitaxial loayer, and transverse axis is represented the distance left from anode region.And, be illustrated in the CONCENTRATION DISTRIBUTION under the state that applies Vf=0.8 (V) on protection diode 1 and the Zener diode 31 respectively among the figure.
At first, as shown in Figure 1, during 1 action of protection diode, apply forward voltage (Vf), and on epitaxial loayer 3, inject free carriers (hole) from p type diffused layer 5 to the PN junction zone of p type diffused layer 5 and N type epitaxial loayer 3.On the other hand, as shown in Figure 2, when Zener diode 31 actions, apply forward voltage (Vf) to the PN junction zone of p type diffused layer 34 and N type epitaxial loayer 33 equally, and on epitaxial loayer 3, inject free carriers (hole) from p type diffused layer 34.That is to say that protection diode 1 and Zener diode 31 the two near zone at p type diffused layer 5,34 all form the concentration in roughly the same free carrier (hole).
Then, as shown in Figure 1, in protection diode 1, by forming Schottky barrier diode, p type diffused layer 7,8,9 separates with p type diffused layer 5 and forms.By this structure, apply the forward PN junction area decreases of voltage (Vf), and the free carrier (hole) that is injected on the N type epitaxial loayer 3 reduces.Its result compares with Zener diode 31, in protection diode 1, reduces in the concentration with the free carrier (hole) of p type diffused layer 5 separate areas.In addition, in epitaxial loayer 3, cause conductivity characteristic measurement modulation (Den Guide degree becomes Tone), make principal current with low ON resistance circulation by distribution free carrier (hole).And, can solve the problem of the big Schottky barrier diode of ON resistance value.
At last, as shown in Figure 1, the cathode zone of protection diode 1 forms the dual diffusion structure that is made of n type diffused layer 10,11.By this structure, at n type diffused layer 10 near zones, the free carrier (hole) that injects from p type diffused layer 5 combines with the free carrier (electronics) that injects from n type diffused layer 10,11 again.At this moment, can promote combination again by n type diffused layer 10 is spread significantly.
In addition, in protection diode 1, on n type diffused layer 10, be formed with the p type diffused layer 12,13 that has applied cathode potential.And, not carrying out described combination again, the free carrier (hole) that arrives p type diffused layer 12,13 is discharged outside epitaxial loayer 3 from p type diffused layer 12,13.Its result, the concentration of the free carrier of cathode zone periphery (hole) descends significantly, also can reduce the concentration of the free carrier (hole) in the epitaxial loayer 3.On the other hand, as shown in Figure 2, the cathode zone of Zener diode 31 also has identical structure, and near the concentration of the free carrier (hole) the cathode zone descends significantly.
As mentioned above, be formed with Schottky barrier diode in the protection diode 1, and form the cathode zone of discharging free carrier (hole) easily from epitaxial loayer 3.By this structure, can reduce the concentration of accumulating near the free carrier (hole) the PN junction zone of protection diode 1.Its result when protection diode 1 disconnects, reduces the absolute value of the time rate of change (di/dt) of reverse reverting electric current, can obtain soft recovery characteristics (ソ Off ト リ カ バ リ one characteristic).And, the destruction that can prevent the protection diode 1 that the time rate of change (di/dt) of reverse reverting electric current causes.
As shown in Figure 8, protection diode 1 for example forms ellipse.At oval-shaped linearity region L, on the central area, dispose the p type diffused layer 5 (by the solid line area surrounded) that is used as anode region.And on oval-shaped linearity region L and curve regions R, that surrounds p type diffused layer 5 forms a ring-type with p type diffused layer 7 (by the double dot dash line area surrounded), 8 (by the zones of dotted line) on every side.As mentioned above, p type diffused layer 7,8 is concentrated Schottky barrier and is relaxed with the electric field on the end 20 (with reference to Fig. 1) of metal level 14 (with reference to Fig. 1), the voltage endurance of protection diode 1 is improved.
On oval-shaped linearity region L and curve regions R, that surrounds p type diffused layer 7,8 forms a ring-type with p type diffused layer 9 (by the chain-dotted line area surrounded) on every side.
On oval-shaped linearity region L and curve regions R, the n type diffused layer 10 (by three chain-dotted line area surrounded) that will be used as cathode zone on every side that surrounds p type diffused layer 9 forms a ring-type.And on the zone that is formed with n type diffused layer 10, overlapping its forms the zone and forms p type diffused layer 12 (by four chain-dotted line area surrounded) annularly with one.In addition, though not shown, overlapping its forms the zone and is formed with p type diffused layer 6 (with reference to Fig. 1) on p type diffused layer 5.In addition, overlapping its forms the zone and is formed with n type diffused layer 11 (with reference to Fig. 1) and p type diffused layer 13 (with reference to Fig. 1) on n type diffused layer 10.
By this structure, protection diode 1 can flow through electric current at oval-shaped linearity region L and curve regions R, and current capacity is improved.In addition,, relax electric field by its curve shape and p type diffused layer 7,8 and concentrate, the voltage endurance of protection diode 1 is improved at oval-shaped curve regions R.In addition, form ellipse, can dwindle component size by protecting diode 1.
At last, at oval-shaped curve regions R,, be the wiring layer and the zone that n type diffused layer 10 intersects that has applied anode potential promptly, at least in the below that is applied with the wiring layer of anode potential (not shown), dispose electric field barrier film 51.Electric field barrier film 51 is for example by forming with the common operation of the operation of the gate electrode that forms MOS transistor (not shown), and formed by polysilicon film.And via the contact hole on the insulating barrier that is formed between epitaxial loayer 3 and the electric field barrier film 51 52,53, electric field barrier film 51 is connected with diffusion layer as cathode zone.That is, on electric field barrier film 51, be applied with identical with cathode potential in fact current potential.By this structure, electric field barrier film 51 has shield effectiveness for the wiring layer that has applied anode potential.And, can prevent owing to the potential difference between cathode potential and the anode potential makes cathode zone counter-rotating, the situation that anode region and area of isolation 19 (with reference to Fig. 1) are short-circuited.
In the present embodiment, the situation that forms silicide layer 21 between p type diffused layer 5 that is used as anode region and p type diffused layer 7 is illustrated.But the invention is not restricted to this.Also can be, for example, will widen between p type diffused layer 5 and the p type diffused layer 7, silicide layer 21 is formed on situation on the wide zone in order to improve forward voltage (Vf) characteristic of Schottky barrier diode of protection diode.In this case, can between p type diffused layer 5 and p type diffused layer 7, apply the p type diffused layer of anode potential again with the almost fixed arranged spaced.And, reduce the curvature changing that silicide layer 21 forms the depletion layer on the zone, can keep the voltage endurance of protection diode.
And, can also form p type diffused layer 5 and be diffused into the more structure in deep than p type diffused layer 7.By making p type diffused layer 5 spread deeplyer, the bottom surface of p type diffused layer 5 is left significantly to vertical direction from epitaxial loayer 3 surfaces than p type diffused layer 7.And, in the depletion layer wide zone in the horizontal direction of p type diffused layer 5 and the border extension of epitaxial loayer 3, expand.Its result can strengthen the distance of leaving of p type diffused layer 5 and p type diffused layer 7, enlarges the formation zone of silicide layer 21.As a result, can improve current capacity on the Schottky barrier diode.In addition, in the scope that does not break away from the object of the invention, can carry out various changes.
Claims (8)
1. a semiconductor device is characterized in that, comprising:
First and second anode diffusion layer of opposite conductivity type, it is separated to form on the semiconductor layer of a conduction type;
The cathode diffusion layer of one conduction type, it is formed on the described semiconductor layer;
The third anode diffusion layer of opposite conductivity type, itself and described second plate diffusion layer link and are formed extended at both sides on described semiconductor layer to described cathode diffusion layer side;
Insulating barrier, it is formed on above the described semiconductor layer;
Anode electrode, it is connected with described first and second anode diffusion layer via the contact hole that is formed on the described insulating barrier, and engages with described semiconductor layer Schottky between described first anode diffusion layer and the second plate diffusion layer,
The metal level that disposes described anode electrode or be connected above the described insulating barrier above described third anode diffusion layer with described anode electrode.
2. semiconductor device as claimed in claim 1 is characterized in that, disposes above the described second plate diffusion layer of described semiconductor layer by offering the end of the described anode electrode that described contact hole forms.
3. semiconductor device as claimed in claim 1 is characterized in that, described second plate diffusion layer is made of the diffusion layer of two kinds of different opposite conductivity type of impurity concentration at least.
4. semiconductor device as claimed in claim 3 is characterized in that, the impurity concentration of described third anode diffusion layer is lower than the impurity concentration of the diffusion layer of the described opposite conductivity type that constitutes described second plate diffusion layer.
5. semiconductor device as claimed in claim 1 is characterized in that, overlaps to form the discharge diffusion layer of opposite conductivity type on described cathode diffusion layer, is connected with cathode electrode in the discharge of described opposite conductivity type on diffusion layer.
6. semiconductor device as claimed in claim 1 is characterized in that, described anode electrode or the metal level that is connected with described anode electrode more extend to described cathode electrode side than described third anode diffusion layer.
7. semiconductor device as claimed in claim 1 is characterized in that, disposes above described anode electrode to described anode electrode and applies the contact hole that the wiring layer of anode potential is used.
8. semiconductor device as claimed in claim 7 is characterized in that, on the described semiconductor layer below the wiring layer that has applied described anode potential, disposes and the idiostatic electric field barrier film of described cathode diffusion layer,
Described electric field barrier film is configured in the zone that the wiring layer that applied described anode potential and described cathode diffusion layer intersect.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005098965 | 2005-03-30 | ||
| JP098965/05 | 2005-03-30 | ||
| JP064619/06 | 2006-03-09 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1855549A CN1855549A (en) | 2006-11-01 |
| CN100454582C true CN100454582C (en) | 2009-01-21 |
Family
ID=37195528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2006100738016A Expired - Fee Related CN100454582C (en) | 2005-03-30 | 2006-03-30 | Semiconductor device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100454582C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009141062A (en) | 2007-12-05 | 2009-06-25 | Panasonic Corp | Semiconductor device and manufacturing method thereof |
| CN101661960B (en) * | 2008-08-26 | 2011-05-04 | 万国半导体股份有限公司 | Structure of Schottky diode or bottom anode Schottky diode formed on the P type substrate |
| CN103094359B (en) * | 2011-10-31 | 2016-05-11 | 无锡华润上华半导体有限公司 | High pressure Schottky diode and preparation method thereof |
| CN104183653B (en) * | 2014-06-19 | 2017-04-12 | 立锜科技股份有限公司 | junction barrier Schottky diode |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62165978A (en) * | 1986-01-17 | 1987-07-22 | Sanyo Electric Co Ltd | Protective diode |
| US5101244A (en) * | 1990-02-28 | 1992-03-31 | Hitachi, Ltd. | Semiconductor schottky device with pn regions |
| CN1140335A (en) * | 1995-05-31 | 1997-01-15 | 日本电气株式会社 | Protecting diode for semiconductor device |
| US20040173820A1 (en) * | 2001-07-17 | 2004-09-09 | Kabushiki Kaisha Toshiba | High withstand voltage semiconductor device |
-
2006
- 2006-03-30 CN CNB2006100738016A patent/CN100454582C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62165978A (en) * | 1986-01-17 | 1987-07-22 | Sanyo Electric Co Ltd | Protective diode |
| US5101244A (en) * | 1990-02-28 | 1992-03-31 | Hitachi, Ltd. | Semiconductor schottky device with pn regions |
| CN1140335A (en) * | 1995-05-31 | 1997-01-15 | 日本电气株式会社 | Protecting diode for semiconductor device |
| US20040173820A1 (en) * | 2001-07-17 | 2004-09-09 | Kabushiki Kaisha Toshiba | High withstand voltage semiconductor device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1855549A (en) | 2006-11-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4944460B2 (en) | Semiconductor device | |
| CN101154689B (en) | Semiconductor device | |
| US9960243B2 (en) | Semiconductor device with stripe-shaped trench gate structures and gate connector structure | |
| US9209109B2 (en) | IGBT with emitter electrode electrically connected with an impurity zone | |
| EP1683202B1 (en) | Trench gate field effect devices | |
| US11217580B2 (en) | Semiconductor device including insulated gate bipolar transistor element and freewheeling diode element | |
| US9954056B2 (en) | Semiconductor device with superjunction structure and transistor cells in a transition region along a transistor cell region | |
| US9620636B2 (en) | Semiconductor device with field electrode structures in a cell area and termination structures in an edge area | |
| US7417282B2 (en) | Vertical double-diffused metal oxide semiconductor (VDMOS) device incorporating reverse diode | |
| US9837498B2 (en) | Stripe-shaped electrode structure including a main portion with a field electrode and an end portion terminating the electrode structure | |
| JP2002280555A (en) | Semiconductor device | |
| US10263086B2 (en) | Semiconductor device with first and second field electrode structures | |
| CN101154690A (en) | Semiconductor device | |
| US20130313634A1 (en) | Power semiconductor device and edge terminal structure thereof | |
| KR100710115B1 (en) | Semiconductor device | |
| CN100454582C (en) | Semiconductor device | |
| US9799738B2 (en) | Semiconductor device with field electrode and contact structure | |
| JP7337739B2 (en) | semiconductor equipment | |
| US20090189240A1 (en) | Semiconductor device with at least one field plate | |
| CN100454583C (en) | Semiconductor device | |
| US20210376065A1 (en) | Semiconductor device and method of producing the same | |
| US20210376066A1 (en) | Semiconductor device and method of producing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20090121 Termination date: 20130330 |