CN207731934U - A kind of unidirectional TVS chips - Google Patents
A kind of unidirectional TVS chips Download PDFInfo
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- CN207731934U CN207731934U CN201820025609.8U CN201820025609U CN207731934U CN 207731934 U CN207731934 U CN 207731934U CN 201820025609 U CN201820025609 U CN 201820025609U CN 207731934 U CN207731934 U CN 207731934U
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Abstract
The utility model discloses a kind of unidirectional TVS chips, substrate including Uniform Doped, the the first special-shaped impurity diffusion zone and the second special-shaped impurity diffusion zone for mixing the impurity opposite with substrate conduction type respectively from the two sides of the substrate and being formed, the first PN junction is formed between the substrate and the first special-shaped impurity diffusion zone, the second PN junction is formed between the substrate and the second special-shaped impurity diffusion zone, second PN junction is equipped with shorting region and/or short-circuited conducting sleeve；The two sides of the unidirectional TVS chips is covered with metal layer.Unidirectional TVS chips described in the utility model are special N+‑P‑N+（Or P+‑N‑P+）First PN junction of the unidirectional TVS electrical characteristics of three layers, double junction structure, including determination and the second PN junction equipped with shorting region and/or short-circuited conducting sleeve, have：1. lower clamp voltage, 2. the surge current tolerance of bigger.
Description
Technical field
The utility model is related to a kind of unidirectional TVS chips, belong to field of semiconductor devices.
Background technology
Transient voltage suppressor diode（Transient Voltage Suppressors、TVS）It is a kind of protection device,
It by by cause by a variety of causes such as being struck by lightning, switch and come across Sensitive Apparatus input, the transient voltage of output end carries out
Peak clipping and play the protective effect to Sensitive Apparatus.Specifically, after the input of Sensitive Apparatus, output node parallel connection TVS, TVS
Blocking state is worked in, therefore it has no effect on the work of Sensitive Apparatus.If TVS has and the matched clamper electricity of Sensitive Apparatus
It presses and the clamp voltage is far below the ceiling voltage that Sensitive Apparatus can bear, then when transient voltage occurs, Sensitive Apparatus
Voltage in associated terminal will not be higher than the clamp voltage of TVS.Sensitive Apparatus will not be by the mistake caused by transient voltage
Electrical stress damage.
Unidirectional TVS is mainly made of a PN junction, as shown in Figure 1, working in reversely, in the work electricity of stand-by operation state
Pressure is less than breakdown voltage；It is more than breakdown voltage in the operating voltage of clamper working condition, is used to eliminate and its operating voltage at this time
The identical transient voltage of polarity（Its I-V characteristic is shown in Fig. 2, its usual reversed I-V characteristic is plotted in I quadrants, forward characteristic be plotted in III as
Limit）.Additionally both direction is eliminated with two-way TVS（It is identical, opposite with its operating voltage polarity）Transient voltage.
In general, the I-V characteristic area after TVS breakdown, with corresponding with specified waveform and the peak I pp of the pulse current of amplitude
Voltage define clamp voltage Vc（See Fig. 2）.When the two fingers number that the electric current is 10 microsecond of rising edge, half failing edge, 1000 microsecond
When waveform, the clamp voltage of TVS is generally 1.3-1.5 times of breakdown voltage；When the electric current is 8 microsecond of rising edge, half failing edge
When double exponential waveforms of 20 microseconds, the clamp voltage of TVS is generally 2-4 times of breakdown voltage.Its power consumption tolerance can be for the former
Several times are to an order of magnitude.It is immune commonly used in ESD with the specified TVS of the condition.For the various TVS of same breakdown voltage,
Lower clamp voltage means can be by the transient voltage clamper occurred at random in lower when being used under identical blocking voltage
Level, caused by this will further decrease transient voltage suffered by protected Sensitive Apparatus electrical over-stress damage probability.
Losses of TVS during bypassing transient energy caused by transient voltage itself simultaneously also reduces.This also increases TVS sheets
The level of the anti-electrical over-stress of body.Therefore clamp voltage is reduced under the premise of other rated values and constant electrical characteristic parameter is always
One target being pursued.
In the breakdown region of unidirectional TVS, close to linear, slope and the clamp voltage bulk resistor total with chip have I-V characteristic
It closes（See the I-V characteristic 1 in Fig. 2）.And two-way TVS, since its chip structure is N+-P-N+Or P+-N-P+Three-decker.（N+-P-
N+Indicate N+The concentration of diffusion region is higher than the concentration in the areas substrate P, similarly hereinafter）The structure can generally show different journeys under high current
The negative resistance effect of degree.It can offset partial pressure caused by bulk resistor and rise and keep I-V characteristic more steep and clamp voltage is made to reduce.Cause
This can make the clamp voltage of the two-way TVS under same electric current low instead identical breakdown voltage if design, making are rationally
In the clamp voltage of unidirectional TVS.
In view of this, the present inventor studies this, a kind of unidirectional TVS chips are specially developed, thus this case generates.
Utility model content
The purpose of this utility model is to provide a kind of unidirectional TVS chips, has lower clamp voltage and larger wave
Gush current tolerance.
To achieve the goals above, the solution of the utility model is：
A kind of unidirectional TVS chips, include the substrate of Uniform Doped, are mixed respectively from the two sides of the substrate conductive with substrate
The opposite impurity of type and the first special-shaped impurity diffusion zone formed and the second special-shaped impurity diffusion zone, the substrate and first different
The first PN junction is formed between type impurity diffusion zone, and the second PN junction, institute are formed between the substrate and the second special-shaped impurity diffusion zone
It states the second PN junction and is equipped with shorting region and/or short-circuited conducting sleeve；The two sides of the unidirectional TVS chips is covered with metal layer.
Preferably, second PN junction is equipped with shorting region, shorting region is the Uniform Doped being embedded into the second PN junction
Substrate region.Shorting region is interconnected with the second PN junction other than shorting region by metal layer.
Preferably, the terminal of second PN junction is equipped with short-circuited conducting sleeve, the short-circuited conducting sleeve is to have identical conduction class with substrate
The cyclic annular shorting region of type and doping concentration.
Preferably, the short-circuited conducting sleeve is the becket being linked together with metal layer.
Preferably, the first PN junction terminal is equipped with passivation layer.First PN junction is that for determining unidirectional TVS breakdown voltages
A knot.
Preferably, the substrate surface is abradant surface, chemical polished surface or mechanical polishing face.
Preferably, the substrate is p-type substrate, the described first special-shaped impurity diffusion zone is the first N-type diffusion region, described
Second special-shaped impurity diffusion zone is the second N-type diffusion region；Alternatively, the substrate is N-type substrate, the described first special-shaped impurity diffusion
Area is the first p type diffusion region, and the described second special-shaped impurity diffusion zone is the second p type diffusion region.
Unidirectional TVS chips described in the utility model are special N+-P-N+（Or P+-N-P+）Three layers, double junction structure,
Include the first PN junction of the unidirectional TVS electrical characteristics of determination, and the second PN junction equipped with shorting region and/or short-circuited conducting sleeve.Above structure
Unidirectional TVS chips have compared under electric current with the common unidirectional TVS chips of same breakdown voltage, identical size：1. more
Low clamp voltage, 2. the surge current tolerance of bigger.
The utility model is described in further detail below in conjunction with drawings and the specific embodiments.
Description of the drawings
Fig. 1 is unidirectional TVS chip structures schematic diagram in the prior art；Wherein 1-1 is PN junction, 1-2 N+Diffusion region, 1-
3 be the P type substrate area of Uniform Doped, 1-4 P+Diffusion region, 1-5 are passivation glass layer；
Fig. 2 is unidirectional TVS chip Is-V performance plots in the prior art；
Fig. 3 is the unidirectional TVS chip structures schematic diagram of embodiment 1；
Fig. 4 is that the unidirectional TVS chips of embodiment 1 are illustrated with the I-V characteristic comparison of unidirectional TVS chips in the prior art
Figure；Wherein characteristic 1 is the I-V characteristic of the unidirectional TVS chips of the prior art；Characteristic 2 is the I-V of the unidirectional TVS chips of the present embodiment
Characteristic；
Fig. 5 is the unidirectional TVS chip structures schematic diagram of embodiment 2；
Fig. 6 is the unidirectional TVS chip structures schematic diagram of embodiment 3.
Specific implementation mode
Embodiment 1
As shown in figure 3, a kind of N+-P-N+The unidirectional TVS chips of structure, include the p-type substrate 1 of Uniform Doped, the p-type
2 faces up and down of substrate 1 mix N-type impurity with method of diffusion respectively and form the first N-type diffusion region 2 and the second N-type diffusion region
3, the first PN junction 4,1 and second N-type diffusion region 3 of the p-type substrate are formed between 1 and first N-type diffusion region 2 of the p-type substrate
Between form the second PN junction 5, second PN junction 5 is equipped with shorting region 6.The present embodiment is covered by the method formation of double side nickel-plated
The first metal layer 7 on 2 surface of the first N-type diffusion region is covered, and is covered in the of 6 surface of the second N-type diffusion region 3 and shorting region
Two metal layers 8.
In the present embodiment, the shorting region 6 is located among the second PN junction 5, and shorting region 6 is a part for p-type substrate 1,
The part is embedded in the second PN junction.Shorting region 6 is interconnected with the third N-type diffusion region 3 other than shorting region 6 by metal layer 8.
That is, shorting region 6 is short-circuited with the second PN junction 5 on 3 surface of the second N-type diffusion region.
First PN junction, 4 terminal is equipped with passivation layer 9, that is, the first PN junction of the present embodiment pair 4 carries out table top glassivation.
First PN junction 4 is that knot for determining unidirectional TVS breakdown voltages.1 surface of p-type substrate be abradant surface, chemical polished surface or
Mechanical polishing face, doping concentration by the first PN junction 4 breakdown voltage and form the diffusion item of the first special-shaped impurity diffusion zone 2
Part determines.Such as：When the breakdown voltage of the first PN junction 4 be 26.7~29.5V when, if choose doping concentration be 4e17~
The substrate of 6.2e17 and the suitable phosphorus diffusion condition for forming the first N-type diffusion region 2, then first PN junction 4 in nearly all region
Breakdown voltage can fall into the range.
When applying voltage to the unidirectional TVS chips and the voltage makes 4 reverse bias of the first PN junction, then its electric current is first
PN junction 4 punctures the shorting region 6 that the first PN junction 4 and the second PN junction 5 are flowed only through in front and back a certain range.Voltage is increased when electric current reaches
Making the second PN junction 5 when to certain amplitude, gradually positively biased is connected, and continues to increase with voltage, flows through the electricity of the second PN junction 5
Stream will account for the exhausted large scale of total current（Total current=short circuit current for flowing through shorting region 6+flows through the electricity of the second PN junction 5 at this time
Stream）.Continue to increase negative resistance effect also more and more by force with 5 electric current of the second PN junction simultaneously, is reached until in a certain upper limit current
To maximum.The reduction of voltage caused by the effect can offset the increase of the body pressure drop caused by electric current increases to a certain extent.
It is final to make the voltage of the entire chip in certain current range with the only smaller increase of the increase of electric current.The present embodiment
The TVS chips a quadrant the practical reversed and clamping performance for the first PN junction 4 of I-V characteristic, and it is general in the prior art
Logical unidirectional TVS is similar, but its clamp voltage is lower, surge current tolerance bigger.I-V characteristic curve 2 as shown in Figure 4.
When the inrush current of TVS chips described in the present embodiment is long wave（Such as 10/1000 double exponential waves）,
If negative resistance effect is made to reach the inrush current that strongest upper limit current is approximately equal to the chip, corresponding clamper at this time
Voltage also by micro- increasing or does not increase, this just obtains the clamp voltage close to breakdown voltage under this condition（See that the I-V in Fig. 4 is special
Linearity curve 2）.
When applying forward voltage to the TVS chips described in the present embodiment, I-V characteristic should be located at III quadrant, and at this time the
One PN junction, 4 positively biased, the second PN junction 5 are short-circuited, therefore total I-V characteristic still shows as positively biased PN junction characteristic（See that the I-V in Fig. 4 is special
Linearity curve 2）.
Unidirectional TVS chips described in the present embodiment are special N+-P-N+The unidirectional TVS of three layers, double junction structure, including determination
First PN junction 4 of electrical characteristics, the second PN junction 5 equipped with shorting region 6.With the common unidirectional TVS of same breakdown voltage, identical size
Chip has compared under electric current：1. lower clamp voltage, 2. the surge current tolerance of bigger.
Embodiment 2
Unidirectional TVS chips described in the present embodiment are N +-P- N +Structure, as shown in Figure 5.Wherein P types substrate 1, first
The passivation layer 9 of N-type diffusion region 2 and surface metal-layer 7, the first PN junction 4 and terminal is same as Example 1.Second N-type diffusion region 13
It is formed with the method for selection phosphorus diffusion, shorting region 10 is located at the surrounding of the second N-type diffusion region 13, is a part for p-type substrate 1.
The surface in the second N-type diffusion region 13 and loop short area 10 is covered with second metal layer 8.Make short-circuited conducting sleeve by second metal layer 8
10 and second N-type diffusion region 13 interconnect.
Embodiment 3
Unidirectional TVS chips described in the present embodiment are N+-P-N+Structure, as shown in Figure 6.Including p-type substrate 1, the first N-type
Diffusion region 2, the second N-type diffusion region 3, the first PN junction 4, the second PN junction 5, the first metal layer 7, second metal layer 8 and passivation layer 9,
The main distinction of itself and embodiment 2 is that short-circuited conducting sleeve is formed by the method for short circuit metal, is equipped in 5 terminal of the second PN junction
The side metal ring 14 being linked together with metal layer 8.The short circuit of the second PN junction 5 is realized by becket 14.
The ring terminal of second PN junction 5 can be exposed to a surface of chip（As shown in Fig. 5 of embodiment 2）Or chip
Side（As shown in Fig. 6 of embodiment 3）, no matter short-circuited conducting sleeve formed with which kind of method, and the surface of terminal must be covered by metal,
And metal layer of the metal area generally with respective surfaces active area is integrated.
Three above embodiment has been all made of N+-P-N+Structure, if by the dopant type of substrate impurity type and diffusion layer
Reciprocity can then form the identical P of geometry+-N-P+Structure.The structure is also the scope of the utility model patent.
The product form and style of above-described embodiment and diagram and non-limiting the utility model, any technical field
The appropriate changes or modifications that those of ordinary skill does it all should be regarded as the patent category for not departing from the utility model.
Claims (7)
1. a kind of unidirectional TVS chips, it is characterised in that：Substrate including Uniform Doped is mixed respectively by the two sides of the substrate
Enter the special-shaped impurity opposite with substrate conduction type and forms the special-shaped impurity diffusion zone of first opposite with substrate conduction type and the
Two special-shaped impurity diffusion zones.The first PN junction, the substrate and second are formed between the substrate and the first special-shaped impurity diffusion zone
The second PN junction is formed between special-shaped impurity diffusion zone, second PN junction is equipped with shorting region and/or short-circuited conducting sleeve；Described first is different
Type impurity diffusion zone surface and the second special-shaped impurity diffusion zone and the surface of shorting region and/or short-circuited conducting sleeve are covered with metal layer.
2. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：Second PN junction is equipped with shorting region, short
Road area is the substrate region for the Uniform Doped being embedded into the second PN junction, and shorting region passes through table with the second PN junction other than shorting region
Face metal layer interconnection.
3. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：The terminal of second PN junction is equipped with short circuit
Ring, the short-circuited conducting sleeve are the cyclic annular shorting region for having with substrate same conductivity type and doping concentration.
4. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：The short-circuited conducting sleeve is to be linked as one with metal layer
The becket of body.
5. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：The first PN junction terminal is equipped with passivation layer.
6. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：The substrate surface is abradant surface, chemistry throwing
Smooth surface or mechanical polishing face.
7. a kind of unidirectional TVS chips as described in claim 1, it is characterised in that：The substrate be p-type substrate, described first
Special-shaped impurity diffusion zone is the first N-type diffusion region, and the described second special-shaped impurity diffusion zone is the second N-type diffusion region；Alternatively, described
Substrate is N-type substrate, and the described first special-shaped impurity diffusion zone is the first p type diffusion region, and the described second special-shaped impurity diffusion zone is
Second p type diffusion region.
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| CN201820025609.8U CN207731934U (en) | 2018-01-08 | 2018-01-08 | A kind of unidirectional TVS chips |
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| CN108110063A (en) * | 2018-01-08 | 2018-06-01 | 浙江明德微电子股份有限公司 | A kind of unidirectional TVS chips |
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| CN108110063A (en) * | 2018-01-08 | 2018-06-01 | 浙江明德微电子股份有限公司 | A kind of unidirectional TVS chips |
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