CN101308870B - Insulated gate transistor and inverter circuit - Google Patents

Abstract

The invention provides an insulated gate transistor and an inverter circuit. The invention improves recovery characteristic of diode action in an FWD built-in insulating gate transistor. In each of IGBT cells, a p-type base layer (2) shaped like a well is formed. And a p<+>-type collector layer (5) and an n<+>-type cathode layer (4) are formed on back side just below the p-type base layer (2). The p-type base layer (2) of each IGBT cell is provided with: (1) a flat region (2FR) which comprises an emitter region (3) and a bottom surface (2BF) penetrated by a main trench (6); (2) first and second side diffusion regions (2SDR1 and 2SDR2) between which the flat region (2FR) is interposed, wherein the first side diffusion region (2SDR1) is located just above the N<+>-type cathode layer (4), longitudinal sections of bottoms (2BS1 and 2BS2) of the two side diffusion regions form slowly changing radiation. If the p<+>-type collector layer (5) is replaced by the n<+>-type cathode layer (4), characterizing portion of the structure also can be applied to a power MOSFET.

Description

Insulated gate transistor and inverter circuit

The application on August 26th, 2004 submit to, application number be 200410064437.8, denomination of invention divides an application for the Chinese patent application of " insulated gate transistor and inverter circuit ".

Technical field

The present invention relates to have insulated gate (MOS structure) transistor (for example, insulated gate bipolar transistor (below, be also referred to as IGBT.In addition, this IGBT is also referred to as anti-conducting type IGBT.) or power MOSFET etc.), particularly, relate to inside installed play fly-wheel diode (below, also be called FWD simply.) diode that acts on and structure and the manufacturing technology thereof with insulated gate transistor of trench gate structure.And the present invention is a technology of seeking to improve the recovery characteristics in the diode action that is installed in the diode in the insulated gate transistor.

Background technology

In the power electronic technology of drive motors even load, in rated voltage is zone more than the 300V,, use IGBT as switch element from its characteristic, and, use simultaneously and be connected in the diode (FWD) that the circulation on this switch element is used in parallel.

Below, record and narrate the structure of groove-shaped IGBT simply.That is, in groove-shaped IGBT, on the P+ collector layer, form the N+ resilient coating, on the N+ resilient coating, form the N-layer.On the surface of N-layer, optionally form the P base by the diffusion p type impurity, and then, on the surface of this P base,, form the emitter region by optionally spreading the N type impurity of high concentration.And then, form from the emitter region to the groove of N-layer, form oxide-film at the inwall of this groove, form the polysilicon gate electrode therein and make this groove of filling.The emitter region and under the N-layer segment between the part of P base become channel region.In addition,, form emitter electrode, on the back side of N+ substrate, form drain electrode on a part of zone on surface, emitter region and on the middle body zone of P base region surface.

Secondly, record and narrate the action of the groove-shaped IGBT with above-mentioned structure.In above-mentioned structure,, between emitter electrode and gate electrode, apply predetermined grid voltage VGE and (that is, make gate turn-on if between emitter electrode and collector electrode, apply predetermined collector voltage VCE.), then the channel region transoid becomes the N type, forms raceway groove.By this raceway groove, inject electronics from emitter electrode to the N-layer, according to this injected electrons, by forward bias, its result is from P+ collector layer injected hole between P+ collector layer and the N-layer (N+ resilient coating), the resistance of N-layer descends significantly, and the current capacity of IGBT increases.Like this, IGBT injects by the hole from the P+ collector layer, has reduced the resistance of N-layer.Secondly, illustrate that IGBT is from the transfer action of conducting state to cut-off state.In above-mentioned structure, if under conducting state, make the grid voltage VGE that is applied between emitter electrode and the gate electrode become 0V or reverse bias (promptly, grid is ended), then transoid becomes the channel region of N type to turn back to p type island region, stops to inject from the electronics of emitter electrode.Injection by this electronics stops, and injects from the hole of P+ collector layer also to stop.Then, be trapped in electronics in the N-layer (N+ resilient coating) and hole or escape to collector electrode and emitter electrode respectively, perhaps compound mutually and disappear.

Then, record and narrate the essential structure of the FWD that is connected in parallel with IGBT with above-mentioned structure.This diode forms the P district of anode on the surface of the N-substrate that is made of the N-floor, and then forms anode electrode in its surface.Order forms N+ cathode layer and cathode electrode on the back side of N-substrate.

Below record and narrate the action of the diode of this structure.In above-mentioned structure, if between anode electrode and N-layer, apply predetermined anode voltage VAK (forward bias), and if anode voltage surpass certain threshold value, then between the P district of anode and the N-floor by forward bias, diode current flow.Secondly, if apply reverse bias between anode electrode and N-layer, then depletion layer extends from anode P course N-layer one side, can keep oppositely withstand voltage.

Current waveform when having illustrated among Figure 38 reverse recovery of this diode of the state of the diode of above-mentioned structure when conducting state changes to cut-off state.Diode is when conducting state is transferred to cut-off state, in the other direction the instantaneous electric current that flows through.The peak value of the electric current that flows through in the other direction along this is called " restoring current Irr ", the milder diode of slope ratio that the electric current this current value during from restoring current Irr to 0 value changes calls " soft recovery ".In addition, though diagram not here, when reverse recovery when on diode, applying supply voltage, long-pending the becoming of this voltage and electric current " recovery loss ".

Generally, as the rectification diode, the constant loss (Vf) when needing conducting state is low, and the loss when oppositely recovering (recovery loss) is low, and electric current recovers the diode of mild (soft recovery) when oppositely recovering.

General inverter circuit is direct current and the interchanger that exchanges, and is made of IGBT and fly-wheel diode (FWD) as switch element, and IGBT and FWD use in the control of motor with 4 elements or 6 elements.The dc terminal of such inverter circuit is connected to DC power supply, and by each IGBT break-make, inverter circuit is dc voltage conversion an alternating voltage, supplies with alternating voltage to the motor as load.

In general inverter circuit,, therefore need above-mentioned fly-wheel diode owing to the motor as load is inductive.The inductive of load means stored energy in the magnetic field that is produced by electric current, and electric current changes the energy of being stored and also changes.Here, the energy storage capability of load inductance is shown as " L ".If be breaking at the electric current that flows through in the load, the energy that then is stored among the L discharges to the object that will cut off electric current, stops the variation of electric current.If instantaneous relase is stored in the energy among the L of motor, the action of IGBT is worsened, become the electric power of size to a certain degree, therefore if cut off the electric current that flows through motor sharp by IGBT, then according to the energy that is discharged, IGBT becomes the state of akinesia.Therefore, in the procedures of turn-off of IGBT, flow through the electric current of motor, make the electric current self that flows through motor not change by switch by the circuitous circulation of fly-wheel diode.More particularly, if DC power supply and motor are linked together, terminate in the IGBT that has applied voltage on the motor, the electric current that then flows through motor is by the energy among the L that is stored in motor, cross direct current through the fly-wheel diode reverse flow, motor becomes and the state that has applied the direct reverse voltage equivalence.If change the conducting and the time scale of shutoff of IGBT, then since direct voltage apply during with reverse flow during ratio change, so can control the voltage that is applied on the motor fifty-fifty.Thereby, if this ratio sinusoidal waveform ground is changed, then needn't cut off the electric current of motor sharp by the switch motion of IGBT, but can be by switch motion from the direct-current power supply alternating voltage.In order to carry out such action, inverter circuit need with the fly-wheel diode of this IGBT differential concatenation, that is, and need be with respect to constituting the fly-wheel diode that this a pair of IGBT reverse parallel connection is connected with certain IGBT.And similarly habitually practise with IGBT is the power MOSFET of switch element owing to have the inner structure that the reverse parallel connection diode is installed, so does not have the outside necessity that connects fly-wheel diode in addition at power MOSFET on circuit.But MOSFET is not suitable for the purposes of big electric current because its current density that can switch on is low.And IGBT is owing to have the structure of the bottom of the N+ layer of vertical MOS FET substrate being changed into the P+ layer, therefore formed diode, the withstand voltage interior value of 20V～50V scope that roughly becomes of this diode between P+ collector layer overleaf and the N+ resilient coating.This value withstand voltage use under the situation of this diode as built-in FWD too high.Therefore, this is withstand voltage to become too high potential barrier for fly-wheel diode, and the heating that the voltage that takes place during owing to circulation produces makes the action of IGBT significantly worsen on the contrary.Therefore, though flow through at element internal on this point of big electric current and we can say that IGBT is more favourable than MOSFET, but under the situation that IGBT is used as the switch element of inverter circuit, above-mentioned other fly-wheel diode is connected on the IGBT needing on the circuit.

According to IGBT in the experience of vertical MOS FET exploitation later on have above-mentioned advantage between the two and the viewpoint of shortcoming, identical with vertical power MOSFET, the diode that plays the fly-wheel diode effect of packing in IGBT inside is considered to the current techniques problem of IGBT, and its result has proposed plurality of proposals up to now.

[patent documentation 1] spy opens the 2002-314082 communique

[patent documentation 2] spy opens the 2000-307116 communique

[patent documentation 3] spy opens flat 9-82954 communique

[patent documentation 4] spy opens flat 8-116056 communique

[patent documentation 5] spy opens flat 7-153942 communique

[patent documentation 6] spy opens flat 6-53511 communique

[patent documentation 7] spy opens flat 6-196705 communique

Open flat 7-153942 communique and the special structure of opening the fly-wheel diode that proposed in the flat 6-53511 communique to pack into the spy in IGBT inside.In the structure that these documents proposed, a side forms the supply source of electronics overleaf, makes surperficial P base play the effect of the anode of diode.But therefore the P base layer of IGBT must be set at its surface concentration about 1E18 owing to determine the value of the threshold voltage vt h of IGBT.

On the other hand, in nearest diode, in order to improve its recovery characteristics, the impurity concentration of anode is set at 1E17 and lower value.

Therefore, the present application person simulates with structure shown in Figure 39 for the influence for recovery characteristics of the surface concentration of investigating anode.That is the model construction of the diode that, simulated possess thickness with 170 μ m and 55 Ω cm resistance values the N-substrate, the N+ layer of thickness 1 μ m that forms on the back side of this N-substrate and surface concentration 6E18 and on the surface of this N-substrate the anode P layer of thickness 3 μ m.And in simulation process, the surface concentration of above-mentioned anode P layer is set at 1E17 and 1E18.At this moment lifetime settings is 10 μ sec.At this moment diode drop (Vf) is 1.23V in the surface concentration of above-mentioned anode P layer during for 1E17, when the surface concentration of above-mentioned anode P layer is 1.07V during for 1E18, has the difference about 15%.Particularly, Figure 40 illustrates the analog result of recovery characteristics.Be appreciated that when the surface concentration of above-mentioned anode P layer is 1E17 and during 1E18, restoring current Irr also differs about 40% from analog result, and Qrr (along the summation of the electric current that flows through) differ more than 50% in the other direction.Shown in this analog result, the value of the surface concentration of anode P layer has produced very big influence for the recovery characteristics of diode.

Therefore, open the structure of the recovery characteristics that has proposed to be used to improve this diode-built-in when in IGBT, having inserted diode in the flat 6-196705 communique the spy.That is, open in the flat 6-196705 communique,, form the structure of P-layer on the P layer that discloses on the surface as the technology of the recovery characteristics that is used to improve diode-built-in the spy.At this communique herein, the channel width of having put down in writing IGBT is 17 μ m, and the channel width of diode is 5 μ m, and the surface concentration of base layer is 5 * 1E18, and the thickness of base layer is 5 μ m.In this communique,,, can think that the base layer width is overall 20% if consider from disclosed accompanying drawing this communique though do not put down in writing the base layer width.Therefore, can think that the effect that forms the P-layer in the P on surface layer is little.Particularly, in the recovery characteristics when big electric current, be overriding owing to inject from the hole of the base layer of high concentration, therefore think in the above-mentioned motion of this communique, the recovery characteristics during big electric current to improve effect little.But, set this zone if merely strengthen, then will cause reverse leakage current and the oppositely deterioration of voltage endurance.Thereby the improvement that the above-mentioned motion of this communique is difficult to for the recovery characteristics of built-in FWD is effective motion.

In addition, though produce the problem points of such " improvement of the recovery characteristics of diode-built-in " especially significantly for the IGBT of FWD internally-arranged type, such problem points we can say it also is the same technical task that produces in the vertical MOS FET of FWD internally-arranged type (power MOSFET).

Summary of the invention

The present invention produces for the dead state that will break this technology, its main purpose is to improve the recovery characteristics of the above-mentioned diode in the insulated gate transistor device (IGBT or vertical MOS FET etc.) with trench gate structure effectively as built-in while of the diode that plays the FWD effect.

The feature of the insulated gate transistor device relevant with theme of the present invention is to possess: the Semiconductor substrate with the 1st conduction type of the 1st interarea and the 2nd interarea; In above-mentioned Semiconductor substrate, form the 1st semiconductor layer of the 2nd conduction type of trap shape from above-mentioned the 1st interarea of above-mentioned Semiconductor substrate, have the 1st side diffusion district, 2nd side diffusion district and the flat region above-mentioned 1st side diffusion district and above-mentioned 2nd side diffusion district between relative with above-mentioned the 1st side diffusion district, the bottom surface of above-mentioned flat region constitutes the general planar face with above-mentioned the 1st interarea almost parallel; Connect the main line of the bottom surface of above-mentioned the 1st semiconductor layer from above-mentioned the 1st interarea, the bottom of above-mentioned main line be arranged in above-mentioned the 1st semiconductor layer of above-mentioned Semiconductor substrate under part; The dielectric film that on the upper bottom of above-mentioned main line and side, forms; The whole face that the is formed on above-mentioned dielectric film control electrode of the above-mentioned main line of filling that comes up; The 2nd semiconductor layer of above-mentioned the 1st conduction type that forms in the above-mentioned flat region of above-mentioned the 1st semiconductor layer from above-mentioned the 1st interarea has the upper surface that is positioned on above-mentioned the 1st interarea, relative with above-mentioned upper surface and constitute the lower surface of bottom and the 1st and the 2nd side that is clipped in the middle and is aimed at mutually by above-mentioned upper surface and above-mentioned lower surface; Be formed on the above-mentioned upper surface of above-mentioned the 2nd semiconductor layer and the 1st main electrode in above-mentioned the 1st side diffusion district of above-mentioned the 1st semiconductor layer; The 4th semiconductor layer of above-mentioned the 1st conduction type that in above-mentioned Semiconductor substrate, forms from above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate; The 2nd main electrode that is formed on above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate and conducts with above-mentioned the 4th semiconductor layer, above-mentioned the 1st side of above-mentioned the 2nd semiconductor layer combines with the above-mentioned side of above-mentioned main line, the bottom surface in above-mentioned the 1st side diffusion district is for the degree of depth of above-mentioned the 1st interarea, from its depth capacity position, surface towards above-mentioned the 1st side diffusion district that is positioned at above-mentioned the 1st interarea and combines with above-mentioned the 1st main electrode, shoal gradually continuously and smoothly, simultaneously, the bottom surface in above-mentioned the 2nd side diffusion district is for the degree of depth of above-mentioned the 1st interarea, from its depth capacity position, surface towards above-mentioned the 2nd side diffusion district that is positioned at above-mentioned the 1st interarea and combines with above-mentioned the 1st main electrode shoals continuously and smoothly gradually.

The invention provides a kind of insulated gate transistor, possess: Semiconductor substrate with the 1st conduction type of the 1st interarea and the 2nd interarea; In above-mentioned Semiconductor substrate, form the 1st semiconductor layer of the 2nd conduction type of trap shape from above-mentioned the 1st interarea of above-mentioned Semiconductor substrate, the 1st semiconductor layer has the 1st side diffusion district, 2nd side diffusion district and the flat region above-mentioned 1st side diffusion district and above-mentioned 2nd side diffusion district between relative with above-mentioned the 1st side diffusion district, and above-mentioned flat region has the 1st bottom surface that constitutes with the general planar face of above-mentioned the 1st interarea almost parallel; From the main line that above-mentioned the 1st interarea forms towards the inside of above-mentioned Semiconductor substrate by above-mentioned the 1st semiconductor layer, this main line is separated from each other above-mentioned the 1st side diffusion district and has than dark bottom, above-mentioned the 1st bottom surface with above-mentioned flat region; The dielectric film that on the whole above-mentioned bottom of above-mentioned main line and side, forms; The whole face that the is formed on above-mentioned dielectric film control electrode of the above-mentioned main line of filling that comes up; The 2nd semiconductor layer of above-mentioned the 1st conduction type that forms in above-mentioned the 1st semiconductor layer from above-mentioned the 1st interarea, the 2nd semiconductor layer have the upper surface that is positioned on above-mentioned the 1st interarea, relative with above-mentioned upper surface and constitute the lower surface of bottom and the 1st and the 2nd side that is clipped in the middle and is aimed at mutually by above-mentioned upper surface and above-mentioned lower surface; In above-mentioned Semiconductor substrate, form and the trap floor of above-mentioned 2nd conduction type relative from above-mentioned the 1st interarea with above-mentioned the 1st side diffusion district; From the 5th semiconductor layer of above-mentioned the 2nd conduction type that forms in above-mentioned Semiconductor substrate from the zone that is clipped in the middle by above-mentioned the 1st side diffusion district and the side diffusion district of above-mentioned trap floor in above-mentioned the 1st interarea, combine with the part in the above-mentioned side diffusion district of the part in above-mentioned the 1st side diffusion district and above-mentioned trap floor, the 5th semiconductor layer has formation and the general planar face of above-mentioned the 1st interarea almost parallel and 2nd bottom surface more shallow than above-mentioned the 1st bottom surface; The 4th semiconductor layer of above-mentioned the 1st conduction type that in above-mentioned Semiconductor substrate, forms from above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate; Be formed on the above-mentioned upper surface of above-mentioned the 2nd semiconductor layer and the 1st main electrode on the upper surface of above-mentioned the 5th semiconductor layer; The 2nd main electrode that is formed on above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate and conducts with above-mentioned the 4th semiconductor layer, above-mentioned the 1st side of above-mentioned the 2nd semiconductor layer combines with the above-mentioned side of above-mentioned main line, above-mentioned the 2nd bottom surface of above-mentioned the 5th semiconductor layer is relative with above-mentioned the 4th semiconductor layer across above-mentioned Semiconductor substrate, and the impurity concentration of above-mentioned the 5th semiconductor layer is lower than the impurity concentration of above-mentioned the 1st semiconductor layer.

Below, with reference to the accompanying drawings with the effect of invention, each object lesson that advantage is at length narrated theme of the present invention.

If according to theme of the present invention, then owing in each unit (for example IGBT unit or vertical MOS FET unit) of insulated gate transistor device, the 1st side diffusion district is set, therefore when be formed in this unit diode (promptly, by the part that the 1st main electrode-the 1st semiconductor layer-Semiconductor substrate-Di 4 semiconductor layers-the 2nd main electrode constitutes) in diode action the time, the quantity of the charge carrier (for example hole) that injects from the 1st semiconductor layer is fewer, can improve the recovery characteristics of the diode-built-in that plays the FWD effect extraordinarily.

Description of drawings

Fig. 1 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 1 is shown.

Fig. 2 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 1 is shown.

Fig. 3 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 1 is shown.

Fig. 4 is the oblique view of another structure of unit cell that the IGBT device of the invention process form 1 is shown.

Fig. 5 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 2 is shown.

Fig. 6 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 2 is shown.

Fig. 7 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 3 is shown.

Fig. 8 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 3 is shown.

Fig. 9 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 3 is shown.

Figure 10 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 3 is shown.

Figure 11 is the oblique view of another structure of unit cell that the IGBT device of the invention process form 3 is shown.

Figure 12 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 4 is shown.

Figure 13 is the sectional arrangement drawing of another structure of unit cell that the IGBT device of the invention process form 4 is shown.

Figure 14 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 15 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 16 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 17 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 18 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 19 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 20 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 21 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 22 is the sectional arrangement drawing that the manufacturing process of the invention process form 5 is shown.

Figure 23 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 24 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 25 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 26 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 27 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 28 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 29 is the sectional arrangement drawing that the manufacturing process of the invention process form 6 is shown.

Figure 30 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 31 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 32 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 33 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 34 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 35 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 36 is the sectional arrangement drawing that the manufacturing process of the invention process form 7 is shown.

Figure 37 is the block diagram that inverter circuit is shown.

Figure 38 is the ideograph of the recovery waveform of diode.

Figure 39 is the sectional arrangement drawing of the structure of the simulation model of use in the problem checking that is illustrated in the past.

Figure 40 is illustrated in the analog result of using in the past the problem checking.

Figure 41 is the sectional arrangement drawing of unit cell configuration of IGBT device that the variation 1 of the invention process form 4 is shown.

Figure 42 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 8 is shown.

Figure 43 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 9 is shown.

Figure 44 is the sectional arrangement drawing of structure of unit cell that the IGBT device of the invention process form 10 is shown.

Figure 45 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 1 of the invention process form 10 is shown.

Figure 46 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 2 of the invention process form 10 is shown.

Figure 47 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 3 of the invention process form 10 is shown.

Figure 48 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 4 of the invention process form 10 is shown.

Figure 49 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 5 of the invention process form 10 is shown.

Figure 50 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 6 of the invention process form 10 is shown.

Figure 51 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 7 of the invention process form 10 is shown.

Figure 52 is the sectional arrangement drawing of structure of unit cell of IGBT device that the variation 8 of the invention process form 10 is shown.

Figure 53 is the vertical view that the graphical configuration in the unit cell of IGBT device of the invention process form 11 is shown.

Figure 54 is the vertical view that the graphical configuration in the unit cell of IGBT device of variation 1 of the invention process form 11 is shown.

Figure 55 is the vertical view that the graphical configuration in the unit cell of IGBT device of the invention process form 12 is shown.

Figure 56 is the vertical view that the graphical configuration in the unit cell of IGBT device of the invention process form 12 is shown.

Figure 57 is the vertical view that the graphical configuration in the unit cell of IGBT device of the invention process form 12 is shown.

Figure 58 is the vertical view that the graphical configuration in the unit cell of IGBT device of the invention process form 12 is shown.

Figure 59 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 60 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 61 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 62 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 63 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 64 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 65 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 66 is the sectional arrangement drawing that the manufacturing process of the invention process form 13 is shown.

Figure 67 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 68 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 69 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 70 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 71 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 72 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 73 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 74 is the sectional arrangement drawing that the manufacturing process of the invention process form 14 is shown.

Figure 75 is the sectional arrangement drawing of unit cell configuration that the groove type power MOS FET device of the invention process form 1 is shown.

Figure 76 is the sectional arrangement drawing of structure of unit cell that the groove type power MOS FET device of the invention process form 8 is shown.

Embodiment

Below, record and narrate each theme of the present invention is useful in situation in the trench gate type IGBT device, and should be careful be each technology clear and definite from the record of each example of the following stated thought as described later, also can be suitable for basically for vertical MOS FET with trench gate structure.

(example 1)

The characteristic point of the IGBT unit (IGBT unit cell+diode-built-in unit) of the trench gate type IGBT device of this example and core are as understanding with reference to sectional arrangement drawing 1 described later, possess I) form the trap shape towards the inside of Semiconductor substrate 1 and have its bottom surface 2BF from the 1st interarea 1US of the Semiconductor substrate 1 of the 1st conduction type (being the N type as an example here) and form flat region 2FR with the tabular surface of the 1st interarea 1US almost parallel, combine with the 1st side diffusion district 2SDR1 of flat region 2FR combination with flat region 2FR and through the 1st semiconductor layer (being P base layer or P base here) 2 of the 2nd conduction type (being the P type as an example here) of the flat region 2FR 2nd side diffusion district 2SDR2 relative with the 1st side diffusion district 2SDR1, II) the flat region 2FR that connects the 1st semiconductor layer 2 from the 1st interarea 1US with and bottom surface 2BF, and, have in the 1st Semiconductor substrate 1, be positioned at the 1st semiconductor layer 2 under the main line 6 of bottom 6B of part (when forming dielectric film 7 all sidedly on the 6S of its side and on the 6B of bottom, inside with control electrode 8 filling main lines 6), III) the 3rd semiconductor layer (being P layer collector layer here) 5 of the 2nd conduction type that in Semiconductor substrate, forms from the 2nd interarea 1LS of Semiconductor substrate 1, IV) from the 2nd interarea 1LS of Semiconductor substrate 1 towards Semiconductor substrate inner form and also with the 4th semiconductor layer (being the N+ cathode layer here) 4 of the 1st conduction type of the 3rd semiconductor layer 5 adjacency, V) the bottom surface 2BS1 of the 1st side diffusion district 2SDR1 is for the depth D P1 of the 1st interarea 1US, bound fraction since the bottom surface 2BF of the bottom surface 2BS1 of the 1st side diffusion district 2SDR1 and flat region 2FR, promptly, from its depth capacity position, surface towards the 1st side diffusion district 2SDR1 that is positioned at the 1st interarea 1US and combines with the 1st main electrode (being emitter electrode here) 10, shoal gradually continuously and smoothly, simultaneously, VI) the bottom surface 2BS2 of the 2nd side diffusion district 2SDR2 is for the depth D P2 of the 1st interarea 1US, bound fraction since the bottom surface 2BF of the bottom surface 2BS2 of the 2nd side diffusion district 2SDR2 and flat region 2FR, promptly, from its depth capacity position, surface towards the 2nd side diffusion district 2SDR2 that is positioned at the 1st interarea 1US and combines with the 1st main electrode 10 shoals continuously and smoothly gradually.And, VII) the 1st side diffusion district 2SDR1 be positioned at diode the 4th conductive layer 4 directly over.Other structure division is as follows.Promptly, the 2nd semiconductor layer of the 1st conduction type (being the emitter region of N+ type here) 3 forms in the flat region 2FR of the 1st semiconductor layer 2 from the 1st interarea 1US, and, the 2nd semiconductor layer 3 possesses the upper surface 3US that is positioned at the 1st interarea 1US, the relative lower surface 3BS that constitutes the bottom with this upper surface 3US, the 1st and the 2nd side 3S1, the 3S2 that are clipped in the middle and aim at mutually by this upper surface 3US and this lower surface 3BS.And the 1st side 3S1 of the 2nd semiconductor layer 3 whole combines with the side 6S of main line 6.That is, in this example, separate predetermined interval and connect via main line 6, watch by left and right sides disjunction from the paper of Fig. 1 along each the 2nd semiconductor layer 3 that the 3rd direction D3 arranges.In addition, the 1st main electrode (being emitter electrode here) 10 is formed on the 1st and the 2nd side diffusion district 2SDR1, the 2SDR2 of (not shown) on the upper surface of the 2nd semiconductor layer 3 and the 1st semiconductor layer 2, the 2nd main electrode (being collector electrode here) 11 is formed on the 2nd interarea 1LS at the back side of Semiconductor substrate 1, its result, the 2nd main electrode 11 are in the state that conducts with the 3rd and the 4th semiconductor layer 5,4.In said structure, " adjacency " when adjoining each other as the 3rd semiconductor layer 5 and the 4th semiconductor layer 4 is to comprise 1) both 4,5 situations about between it, being in contact with one another without the part of Semiconductor substrate 1 fully, 2) both 4,5 between it through the part of the Semiconductor substrate 1 and relative situation of configuration.The meaning of this respect term all is appropriate in all examples described later and various variation.Below, follow the structure that this point is recorded and narrated this IGBT unit in more detail.

Fig. 1 is the sectional arrangement drawing of structure of trench gate type IGBT that the diode internally-arranged type of the invention process form 1 is shown.Among Fig. 1, the 1st direction D1 is equivalent to the main line 6 with gate electrode 8 fillings, P base layer 2, separately the orientation of P+ collector layer 5 and N+ cathode layer 4 (thereby, be also referred to as the main line orientation), to this, the 2nd direction D2 with the 1st direction D1 quadrature in same illustrates the depth direction of main line 6 and P base layer 2 or the thickness direction of Semiconductor substrate 1 (therefore, also the 2nd direction D2 being called the main line depth direction).On the other hand, with the 3rd direction D3 of the paper quadrature of Fig. 1 be main line 6, P base layer 2, P+ collector layer 5 and N+ cathode layer 4 bearing of trend separately, thereby be also referred to as the main line bearing of trend.In this sectional arrangement drawing, on the surperficial 1US of N-substrate 1, by optionally spreading the impurity of P type, optionally form the P base 2 of trap shape, and then on the surface of this P base 2 by the high N type impurity of concentration of comparing with the impurity concentration of Semiconductor substrate 1 of diffusion optionally, formation emitter region 3.And connect emitter region 3 and P base 2 to form the 1st groove up to N-layer 1 in be main line 6 from the surface of emitter region 3, in this main line 6, passes through gate insulating film 7, formation gate electrode 8.And then, P base layer 2 have along with since the 1st groove 6 away from the 1st direction D1, side diffusion district 2SDR1,2SDR2 that its diffusion depth DP1, DP2 shoal.As mentioned above, form gate insulating film 7,, form the gate electrode 8 of polysilicon on the top of gate insulating film 7 in the inside of main line (the 1st groove) 6.For the 1st direction D1 be positioned at gate electrode 8 under the part of flat region 2FR of P base 2 become the channel region of this IGBT unit cell.In addition, interlayer dielectric 9 also passes through gate insulating film 7, forms along groove bearing of trend D3, makes that the upper surface and the top of N+ emitter region 3 that cover the gate electrode 8 in the main line 6 are the surface.Among Fig. 1, on the surface of N+ emitter region 3, form gate insulating film 7, but in fact, in the zone beyond the part that Fig. 1 describes, by partly remove in this zone interlayer dielectric 9 and under gate insulating film 7, on the surface part (not shown) of the N+ emitter region 3 of partly exposing, formation for example constitutes emitter electrode (the 1st main electrode) 10 by Al.In addition, as Fig. 1 expresses, on the surface of the P base 2 that is positioned at the 1st interarea 1US, that is, upward and on the upper surface of two side diffusion district 2SDR1,2SDR2 also form emitter electrode 10 all sidedly in this middle body zone, surface (upper surface of flat region 2FR).On the other hand, on the lower surface 1LS of N-substrate 1, form P+ collector layer 5 and N+ cathode layer 4 feasible adjoining each other respectively, and then collector electrode (the 2nd main electrode) 11 is electrically connected with N+ cathode layer 4 with P+ collector layer 5 respectively and mechanicalness is connected.

Secondly, record and narrate the action of the IGBT element (also being called IGBT simply) in this IGBT unit.In the structure of Fig. 1,, between emitter electrode 10 and gate electrode 8, apply predetermined grid voltage VGE if between emitter electrode and collector electrode, apply predetermined collector voltage VCE, promptly, if make gate turn-on, then the channel region transoid is the N type, forms raceway groove.By this raceway groove, electronics is injected into N-layer (Semiconductor substrate) 1 from emitter electrode 10.According to this injected electrons, by forward bias, the hole is injected in the N-layer 1 from P+ collector layer 5 between P+ collector layer 5 and the N-layer 1, its result, and the resistance of N-layer 1 descends significantly, and the current capacity of IGBT especially improves.In contrast, the conducting state from this IGBT is as follows to the transfer action of cut-off state.In the structure of Fig. 1, if make the grid voltage VGE that in conduction period, adds between emitter electrode 10 and the gate electrode 8 become 0 or the reverse bias value, that is, grid ended, then transoid becomes the channel region of N type to turn back to p type island region, stops to inject from the electronics of emitter electrode 10.By stopping that this electronics injects, also stop from the injection in the hole of P+ collector layer 5.Then, escape to collector electrode 5 and emitter electrode 10 respectively in the electronics and the hole that are trapped in the N-layer 1, perhaps compound mutually and disappear.In addition, under cut-off state, be added in collector voltage VCE between emitter electrode 10 and the collector electrode 5 by the impurity concentration of N-layer 1 and thickness decision thereof.

In addition, in this IGBT unit, form N+ cathode layer 4 at N-substrate lower surface 1LS and make and P+ collector layer 5 adjacency.Therefore, if on this IGBT, apply voltage VE C, then, flow through forward current in the diode that the P base layer 2 of N-substrate 1 and N-substrate top surface 1US one side forms by N+ cathode layer 4 with the energy that is stored among the outside load L (not shown).That is, this diode becomes conducting state, plays the FWD effect of corresponding IGBT unit cell protection usefulness.That is, the diode-built-in that forms according to this N+ cathode layer 4 plays the effect of the fly-wheel diode of replacement reverse parallel connection connection in the past.

And then, in the diode conducting state under, then, if be connected in series to IGBT (not shown) on this diode, then inject and inject and all stop from the electronics of negative electrode N+ layer 4 from the hole of the P base layer 2 in this diode to the conducting state transitions.Then, being trapped in the remaining charge carrier in the substrate 1, escapes to collector electrode 11 and emitter electrode 10 1 sides respectively in the electronics and the hole that promptly are trapped in the N-layer 1, perhaps compound mutually and disappear.At this moment, in this diode, flow through restoring current as has been described like that.

Generally, the restoring current of known diode depends near the density of the charge carrier of diode anode.According to this phenomenon, if can suppress to inject, then can reduce near the carrier density the anode from the hole of P base layer, therefore at diode from the recovery of conducting state when cut-off state shifts moved, restoring current reduces.

In the structure of the IGBT of this example, compare with IGBT structure in the past, in each main line 6 or each IGBT unit cell, form P base layer 2 separately or partly, and, there is not each lateral parts 2SDR1 by the P base layer 2 of main line 6 disjunctions, 2SDR2 forms the side diffusion district of its bottom sectional shape of formation from the radioactive ray of the slow lasting inclination in maximum bottom, and whole ground forms emitter electrode 10 on each side diffusion district upper surface.Therefore, the hole of each side diffusion district 2SDR1, the 2SDR2 during this diode conducting amount is injected to compare with the structure of in the past IGBT and is suppressed extraordinarily.Inject by this repressed hole, near the carrier density during the anode of diode is especially descends, and its result has reduced restoring current.

The variation 1 of＜example 1 〉

The characteristics of this variation and variation described later 2 be also to be provided with from the 1st interarea 1US connect the bottom surface 2BS1 of the 1st side diffusion district 2SDR1 and in Semiconductor substrate 1, have be positioned at the 1st side diffusion district 2SDR1 under the secondary trenches 12 of bottom 12B of part.Certainly, for the 2nd side diffusion district 2SDR2, also same secondary trenches 12 can be set.

For example, shown in the sectional arrangement drawing of Fig. 2, with two the side diffusion district (2SDR1 that belong to each IGBT unit cell respectively that aim at mutually along main line orientation D1,2SDR1), (2SDR2, the form of inserting 2SDR2), in other words, perforation is from each side diffusion district 2SDR1, the bottom surface 2BS1 of 2SDR2, the bound fraction of 2BS2 and the 1st interarea 1US with and near part towards the part in two inner relative side diffusion districts of Semiconductor substrate 1 time, form the 2nd groove or the secondary trenches 12 that extends in parallel with main line 6 along main line bearing of trend D3.

The advantage or the starting point that such secondary trenches 12 is set are as follows.That is, because that electric field among each side diffusion district 2SDR1, the 2SDR2 and the zone that does not have side diffusion are that flat region 2FR compared is strong, its result is easy to cause reverse leakage current and withstand voltage reduction.Therefore, as mentioned above, by form the side diffusion district between main line 6 and secondary trenches 12, the electric field strength with in the channel shaped mitigation side diffusion district of secondary trenches 12 can prevent reverse leakage current and withstand voltage reduction.

Here, the interval d1 of the central shaft of the secondary trenches 12 of the central shaft of main line 6 and the 1st side diffusion district 2S,DR1 one side, the central shaft of main line 6 is identical mutually in the example of Fig. 2 with the interval d2 of the central shaft of the secondary trenches 12 of the 2nd side diffusion district 2S,DR2 one side, and general two intervals d1, d2 also can be different mutually.In addition, needn't be consistent about the width dimensions 12W of the 1st direction D1 of each secondary trenches 12 with the width dimensions 6W of main line 6, same, also needn't be consistent about the depth dimensions D of the 2nd direction D2 of each secondary trenches 12 with the depth dimensions of main line 6.But, as shown in Figure 2, make width dimensions 12W and the width dimensions 6W advantage that will bring in the manufacturing consistent with each other, same, the depth dimensions advantage of also bringing in the manufacturing consistent with each other of the depth dimensions D of the bottom 12B by making secondary trenches 12 and the bottom 6B of main line 6.In addition, as mentioned above, also will bring advantage in the manufacturing by setting d1=d2.And then the material of each secondary trenches 12 inside of filling both can be that metal material also can be the insulating properties material.Under each situation, all there is not difference aspect the advantage in above-mentioned manufacturing.Wherein, whole ground forms gate insulating film on the 12B of the bottom of each secondary trenches 12 and on the side, therefore the structure that is full of each secondary trenches 12 inside with the such conductive materials of polysilicon brings the advantage in the manufacturing too owing to the manufacturing process with main line 6 one sides structure is complementary.

The variation 2 of＜example 1 〉

In order further to relax the electric field strength among each side diffusion district 2SDR1, the 2SDR2, shown in the sectional arrangement drawing of Fig. 3, also can form two secondary trenches (the 2nd groove) 12 belonging to two side diffusion districts (2SDR1,2SDR1) that each IGBT unit cell is aimed at simultaneously mutually respectively, (2SDR2,2SDR) is clipped in the middle.In this case, each secondary trenches 12 is in the bottom surface 2BS1 of corresponding side diffusion district 2SDR1,2SDR2, the inside of 2BS2, only connect the bound fraction near the bottom surface 2BF of bottom surface 2BS1, the 2BS2 of this side diffusion district 2SDR1,2SDR2 and flat region 2FR, each bottom surface 2BS1, the 2BS2 of the 1st and the 2nd side diffusion district 2SDR1,2SDR2 still arrive the 1st interarea 1US.

The variation 3 of＜example 1 〉

Fig. 4 is the oblique view that the IGBT unit structure of this variation is shown, and, also be illustrated in the profile construction that has cut off main line 6 in the face with the 1st direction D1 and the 2nd direction D2 regulation along the longitudinal.In addition, among Fig. 4, for illustrated convenience, the suitable emitter electrode of whole of the upper surface of various piece 2FR, the 2SDR1 of diagram and P base layer 2,2SDR2 electrode that combine and Fig. 1 10 not.

The characteristic point of structure shown in Figure 4 and the structure of Fig. 1 contrast, each IGBT unit cell is for main line bearing of trend D3, has flat region 2FR, the 1st side diffusion district 2SDR1 suitable that combine with this zone 2FR with the 1st side diffusion district Fig. 1, combine with flat region 2FR and also through flat region 2FR at the main line bearing of trend D3 2nd side diffusion district 2SDR2 relative with the 1st side diffusion district 2SDR1.Thereby, for each the 1st side diffusion district 2SDR1 of two mutually adjacent IGBT unit cells of main line bearing of trend D3 to aim at mutually with the form that the 1st side diffusion district 2SDR1 of a relative side's IGBT unit cell is in contact with one another on the 1st interarea 1US.Structure about this main line bearing of trend d3 also is appropriate for the 2nd side diffusion district 2SDR2.And, each the 1st side diffusion district 2SDR1 be positioned at the 4th semiconductor layer 4 directly over.In addition, in Fig. 4, each emitter region 3 only in the flat region 2FR of the 2nd semiconductor layer 2 in corresponding IGBT unit cell, exists with the form of extending along main line bearing of trend D3.Different therewith, each main line 6 is with crosscut or intersect all and to arrange and the 1st side diffusion district 2SDR1 of the mutual aligning that extends along main line orientation D1 and the form of the 2nd side diffusion district 2SDR2 of aligning mutually along main line bearing of trend D3, extends along main line bearing of trend D3.

In the structure of Fig. 4, also can access the action effect same certainly with the structure of Fig. 1.

(example 2)

Fig. 5 is the sectional arrangement drawing that near the structure the IGBT unit cell of this example one example is shown.In the structure of Fig. 5, compare with the IGBT unit structure of Fig. 1, in the trap of the 1st semiconductor layer 2, form two main lines 6 with the form that connects this P base layer 2, its result, the flat region 2FR of the 1st semiconductor layer 2 is clipped in the middle by two main lines 6.And, be positioned at N+ cathode layer 4 directly over the depth capacity position that combines from side of the depth D P1 of bottom surface 2BS1 of the 1st side diffusion district 2SDR1 at n place with corresponding main line 6, shoal gradually towards bonding part with the 1st interarea 1US, make bottom surface 2BS1 constitute the linear vertical section shape of radiation, equally, the depth capacity position that the depth D P2 of the bottom surface 2BS2 of the 2nd side diffusion district 2SDR2 combines from the side with corresponding main line 6, shoal gradually towards bonding part, make bottom surface 2BS2 constitute the linear vertical section shape of radiation with the 1st interarea 1US.And, on the upper surface of the flat region 2FR that is clipped in the middle by two the 1st grooves 6, form two N+ emitter layers 3 of mutual aligning (though do not illustrate for the 1st direction D1, but it is identical with the structure of Fig. 1, this layer 3 directly is connected with emitter electrode 10), on the 1st interarea 1US of the N-layer 1 that each the 2nd side 3S2 by two N+ emitter layers 3 is clipped in the middle, directly form emitter electrode 10, as mentioned above, at the P base layer 2 of an opposite side that is positioned at the 1st groove 6, form the 1st and the 2nd side diffusion district 2SDR1,2SDR2.

In this structure, owing to also on the side diffusion district of P base layer 2 2SDR1,2SDR2, form emitter electrode 10, therefore can obtain when the turn-on action of this diode, suppressing injection rate from the hole of each side diffusion district 2SDR1,2SDR2, near the anode of this diode carrier density descends, and restoring current reduces such action effect.

In addition, in the structure of Fig. 5, in diode region, only form side diffusion district 2SDR1, the 2SDR2 of the P base layer 2 of IGBT element.Therefore, when forming the P base of IGBT element, only partly form the P base layer and just can access this structure.

In addition, in side diffusion district 2SDR1,2SDR2, compare with the P base layer of expanding formation usually like that, owing to reduce the injection rate in hole extraordinarily with planar bottom surface, therefore near the carrier density the anode sharply descends, and the restoring current value of diode descends.

The variation 1 of＜example 2 〉

Also can be useful in the secondary trenches of in each variation of example 1, recording and narrating 12 in the structure of the illustrative example 2 of Fig. 5, can access same action effect.The sectional arrangement drawing of Fig. 6 illustrates such suitable example.The secondary trenches of Fig. 6 (the 1st and the 2nd secondary trenches) 12 is equivalent to the secondary trenches 12 (the 1st and the 2nd secondary trenches) of Fig. 2.

In addition, in the structure of Fig. 6, in diode area, only form side diffusion district 2SDR1, the 2SDR2 of the P base layer 2 of IGBT element.Therefore, when forming the P base layer of IGBT element, only partly form the P base layer and just can access this structure.

In addition, among side diffusion district 2SDR1, the 2SDR2 in Fig. 6 structure,, reduce the injection rate in hole extraordinarily owing to compare with the P base with planar bottom surface of common formation, therefore near the carrier density the anode sharply descends, and the restoring current value of diode reduces.

(example 3)

The core of this example is as understanding from the illustrative structure of sectional arrangement drawing of aftermentioned Fig. 7, being that (I) also possesses from the 1st interarea 1US forms in Semiconductor substrate 1, and separate the trap floor WL of predetermined 2nd conduction type relative with the 1st side diffusion district 2SDR1 for the 1st direction D1 apart from 13W, (II) in the 1st interarea 1US, on district 1USWR between the trap that is clipped in the middle by the bound fraction of the bottom surface 2BS1 of the bound fraction of the bottom surface 2BS of trap floor WL and the 1st interarea 1US and the 1st side diffusion district 2SDR1 and the 1st interarea 1US, also form the 1st main electrode 10, and, (III) in the part of 1st main electrode 10 of district directly over the 1USWR between trap and between the part of the Semiconductor substrate 1 under the district 1USWR between this trap, form and present the silicide film (for example silicide layer that constitutes by platinum and silicon) 13 of schottky junction or have than the little impurity concentration of the 1st semiconductor layer 2 and trap floor WL and have than the 1st semiconductor layer 1, the semiconductive thin film (being shallow P-floor here) 13 of the 2nd conduction type of the thickness that the part of the 1st main electrode 10 of district 1USWR top also approaches between trap floor WL and trap.Below, record and narrate particularly with reference to the accompanying drawings.

Fig. 7 is the sectional arrangement drawing that near the structure the IGBT unit cell of this example one example is shown.In the structure of Fig. 7, compare with the structure of the IGBT unit of Fig. 1, each side diffusion district 2SDR1 along two adjacent P base layers 2 of the 1st direction D1,2SDR is relative for the 1st direction D1 partition distance 13W, and, by these relative side diffusion district 2SDR1, on the upper surface 1USWR of the part of the N-layer 1 that 2SDR is clipped in the middle, directly whole ground forms emitter electrode 10, and, between the emitter electrode part directly over the district 1USWR between N-layer segment under the district 1USWR between trap and trap, for example whole ground forms the film 13 of the such formation schottky junction of silicide film, perhaps constitutes the semiconductive thin film 13 that has invested the shallow P-layer of meaning with above-mentioned definition.Therefore, in the interface of the N-layer segment between the back side of film 13 and trap under the district 1USWR, form schottky junction or be the state of standard with it.Counterpart in other structure and Fig. 1 structure is identical.The action of the IGBT unit cell in Fig. 7 structure is identical with the action of the IGBT unit cell of Fig. 1 basically.

The diode of this example in Fig. 7 structure manifested it when carrying out diode action as FWD and had meaning.Promptly, in the structure of Fig. 7, at first, be injected between trap the N-layer segment under the district 1USWR as the electronics of majority carrier from the silicide film 13 that constitutes schottky junction or the semiconductive thin film 13 that constitutes shallow P-floor, then, from P base layer 2 injected holes, the part of injected hole combines with the above-mentioned electronics that injects from silicide film 13 or semiconductive thin film 13 and disappears.Its result, the structure of Fig. 7 is compared with the structure of Fig. 1, can further reduce the carrier density under the P base layer.Therefore, because the schottky junction or the shallow P-layer that use film 13 to produce, further suppress injection rate from the hole of P base layer 2, therefore can further reduce near the carrier density of anode, from the recovery action of conducting state when cut-off state shifts, further reduce restoring current at diode.

In addition, the structure of Fig. 7 is compared with the structure of Fig. 1, owing to further expand the central shaft interval of the 1st groove 6 that plays the grid effect, therefore we can say existing problems aspect the reverse withstand voltage maintenance of IGBT, yet interval 13W owing to district 1USWR between the surface area that can freely set film 13 or trap, therefore by this surface area or the suitable selection of 13W at interval, can relax above-mentioned problem points.

The variation 1 of＜example 3 〉

The core of this variation is also to possess " among the district 1USWR, having the secondary trenches 12 of the bottom 12 of the part that is arranged in the Semiconductor substrate 1 under the film 13 (silicide film 13 or semiconductive thin film 13) between the trap of the 1st interarea 1US " this point.

Promptly, in the structure of Fig. 7, be not only the side diffusion district, and constitute the silicide film 13 of schottky junction or the electric field strength that constitutes in the semiconductive thin film 13 of shallow P-layer also raises, and, owing to constitute the silicide film 13 of schottky junction or constitute the work function of semiconductive thin film 13 of shallow P-layer smaller, therefore to compare with PN junction, the leak volume of charge carrier increases.Thereby, as shown in Figure 8, in the zone that forms schottky junction or shallow P-layer, form secondary trenches 12 as the 2nd groove with the form that extends in parallel with main line 6.Like this, the secondary trenches 12 of Fig. 8 is owing to be under the film 13 that forms schottky junction or shallow P-layer, and extend to N-floor 1 inside that is clipped in the middle by two side diffusion district 2SDR, 2SDR1, therefore pass through the existence of this secondary trenches 12, the electric field strength that is added on schottky junction or the shallow P-layer can be relaxed, reverse leakage current and withstand voltage reduction can be prevented effectively.In addition, in the interface of the upper surface of secondary trenches 12 and emitter electrode 10, there be alloy film (when film 13 forms silicide films) or shallow P-layer (when film 13 forms shallow P-layer) (not shown among Fig. 8) (this point also is appropriate to each groove 12 of Fig. 9 described later and Figure 10).Thereby, around the edge of secondary trenches 12, have film 13.

The variation 2 of＜example 3 〉

The main points of this variation are also to be provided with " between the trap of the 1st interarea 1US among the district 1USWR, has near a plurality of secondary trenches 12 of bottom 12B of the part of the Semiconductor substrate 1 being arranged under the film 13 (silicide film 13 or semiconductive thin film 13).」。

That is, shown in the sectional arrangement drawing of Fig. 9, can also make the illustrative secondary trenches 12 of Fig. 8 more than 2.In addition, at this moment make to form each secondary trenches 12, can also realize the further mitigation of electric field strength by a part that eliminates corresponding side diffusion district 2SDR1,2SDR.Particularly as shown in Figure 9, surround the silicide 13 that constitutes schottky junctions with the 2nd groove 12 or constitute the structure of semiconductive thin film 13 of shallow P-layer very effective for the leakage current that suppresses in the semiconductive thin film 13.

The variation 3 of＜example 3 〉

The main points of this variation are " center axle base d2, the d3 in the secondary trenches that adjoins each other in a plurality of secondary trenches 12 is set at than the littlest near the secondary trenches of the main line in the 1st semiconductor layer 6 and the center axle base d1 between this main line 6 in a plurality of secondary trenches 12 " (d2＜d1, d3＜d1).

Promptly, as shown in figure 10, to be set at the interval d1 of the 2nd groove 12 that is adjacent than the 1st groove 6 narrow for interval d2, the d3 (d2=d3 here) between the 2nd groove 12 that adjoins each other through the semiconductive thin film 13 of the silicide film 13 that constitutes schottky junction or shallow P-layer.By making such structure, can further relax as the silicide film 13 of the reason of leakage current or the electric field strength in the semiconductive thin film 13, can further improve the leakage current in schottky junction or the shallow P-layer.

The variation 4 of＜example 3 〉

The structure of this variation shown in the oblique view of Figure 11.This structure is that the distinctive structure of recording and narrating among Fig. 7 (silicide film 13 or semiconductive thin film 13 this point are set) is applied in example in the structure of Fig. 4, also can access the action effect same with the structure of Fig. 7 here.

(example 4)

This example is that the distinctive structure of recording and narrating in example 3 (silicide film 13 or semiconductive thin film 13 this point are set) is useful in situation in the structure of illustrative example 2 among Fig. 5 etc., also can access the action effect same with example 3 here.Below, be described in detail with reference to the accompanying drawings.

Figure 12 is the sectional arrangement drawing that near the structure the IGBT unit cell of this example is shown.The structure of Figure 12 is compared with the IGBT unit cell configuration of Fig. 7, on the 1st interarea 1US that in the flat region 2FR that is clipped in the middle by 2 main lines 6 in the P base layer 2 and by the emitter layer 3 of mutual aligning, is clipped in the middle, directly form emitter electrode 10, and, form side diffusion district 2SDR1,2SDR this point difference in the lateral parts of the P base layer 2 in each main line 6 opposite sides, other each point is identical with the structure of Fig. 7.Thereby this example also structure with Fig. 7 is identical, can control the carrier density under the P base layer.Thereby, by using the silicide film 13 that constitutes schottky junction or constituting the injection of semiconductive thin film 13 inhibition of shallow P-layer from the hole of P base layer, can reduce near the carrier density of anode, the recovery action of diode when conducting state changes to cut-off state, can further reduce restoring current.

In addition, in the structure of Figure 12, in diode area, only form side diffusion district 2SDR1, the 2SDR2 (2SDR) of the P base layer 2 of IGBT element.Therefore, when forming the P base layer of IGBT element, only partly form the P base layer and just can access this structure.

In addition, among side district 2SDR1, the 2SDR2 (2SDR) in Figure 12 structure, compare with the P base that spreads formation usually like that with planar bottom surface, owing to reduce the injection rate in hole extraordinarily, therefore near the carrier density the anode sharply descends, and the restoring current value of diode reduces.

In addition, as shown in figure 13, also a plurality of secondary trenches 12 can be set in the structure of Figure 12, in this case, carry out the control of withstand voltage reduction and leakage current as has been described like that.

In addition, in the structure of Figure 13, also in diode area, only form side diffusion district 2SDR1, the 2SDR2 (2SDR) of the P base layer 2 of IGBT element.Thereby, when forming the P base layer of IGBT element, only partly form the P base layer and just can access this structure.And, among side diffusion district 2SDR1 in the structure of Figure 13, the 2SDR2 (2SDR), compare with the P base that spreads formation usually like that with planar bottom surface, owing to reduce the injection rate in hole extraordinarily, therefore near the carrier density the anode sharply descends, and the restoring current value of diode reduces.

The variation 1 of＜example 4 〉

Figure 41 illustrates the structure of this variation.If the structure of Figure 41 is compared with the structure that becomes its basic Figure 12, then in this variation, near the main line 6 that regional 2FR is separated with the 1st side diffusion district 2SDR1, when resetting the secondary trenches 12 that connects P trap layer, its surface is whole to make that the regional 14FR of the P type in two grooves 6,12 that is clipped in is invalid by covering with dielectric film.

Promptly, secondary trenches 12 is separated the 1st major opposing side diffusion region 14 of the major part that constitutes diode with the 1st smooth dead space 14FR, form dielectric film on the bottom of secondary trenches 12 12B and side thereof whole, fillers such as polysilicon are through above-mentioned dielectric film filling secondary trenches 12.The bottom surface 14FRBS of the 1st dead space 14FR is more shallow than bottom 6B, the 12B of two grooves 6,12, and the surperficial 14FRUS that is positioned at this zone 14FR of the 1st interarea 1US covers with dielectric film (interlayer dielectric) 14IF on whole, with the 1st main electrode 10 electric insulations.In addition, dead space 14FR is not only in the 1st side diffusion district 2S,DR1 one side, and is arranged on the 2nd side diffusion district one side equally.In other words, left and right symmetrically is provided with secondary trenches 12 and dead space 14FR (the 1st and the 2nd major opposing side diffusion region, the 1st and the 2nd secondary trenches, the 1st and the 2nd dead space, the 1st and the 2nd interlayer dielectric) in a P type trap.

As described above, under the situation of the surperficial 14FRUS that integrally covers dead space 14FR with dielectric film and two side, dead space 14FR the earliest can not be as the run of diode, there is not part fully from the hole injection rate of dead space 14FR, reduce to the injection rate of Semiconductor substrate 1 in the hole, can reduce near the carrier density of anode, its result can make the restoring current of diode reduce.

In addition, in the structure of Figure 41, in diode area, only form the 1st and the 2nd major opposing side diffusion region 14 of the P base layer 2 of IGBT element.Thereby, when forming the P base layer of IGBT element, only partly form the P base layer and just can access this structure.

In addition, in the 1st and the 2nd major opposing side diffusion region 14 in the structure of Figure 41, compare with the P base that spreads formation usually like that with planar bottom surface, owing to reduce the injection rate in hole extraordinarily, therefore near the carrier density the anode sharply descends, and the restoring current value of diode reduces.

In addition, can also be useful in the distinctive inscape of the 1st and the 2nd major opposing side diffusion region the 14, the 1st shown in Figure 14 and the 2nd groove the 6, the 1st and the 2nd secondary trenches the 12, the 1st and the 2nd dead space 14FR, the 1st and the 2nd interlayer dielectric 14IF in the structure of Figure 13, at this moment, also can access described action effect for Figure 41.And, in such variation, in diode region, also only form the 1st and the 2nd major opposing side diffusion region 14 of the P base layer 2 of IGBT element.Therefore, when forming the P base layer of IGBT element, only partly form the P base layer and just can access this structure.And then, in the 1st and the 2nd major opposing side diffusion region 14 in the structure of this variation, compare with the P base that spreads formation usually like that with planar bottom surface, owing to reduce the injection rate in hole extraordinarily, therefore near the carrier density the anode sharply descends, and the restoring current value of diode reduces.

Below record and narrate manufacture method of the present invention.

(example 5)

Figure 14～Figure 22 is the sectional arrangement drawing of device configuration that each technology of the device that is used for shop drawings 1 is shown.In technology shown in Figure 14, at first, prepare to become the N type silicon substrate 1 of N-substrate or N-layer.Then, in technology shown in Figure 15, on the surface of N-layer 1, optionally form the P base layer 2 that each IGBT unit cell is used.At this moment, each P base layer 2 possesses flat region 2FR and the 1st and the 2nd side diffusion district 2SDR1,2SDR2.Then, in technology shown in Figure 16, with the central suitable flat region 2FR of P base layer 2 in, optionally form emitter region 3.Then, in technology shown in Figure 17, form the groove (main line) 6 that arrives N-substrate 1 from P+ emitter layer 3, whole ground forms dielectric film 7 in the inside of groove 6.Then, in technology shown in Figure 180, on the surface of N-substrate 1, form polysilicon layer, by polysilicon layer is corroded, form then the polysilicon 8 of whole filling in the groove 6 as conductive materials.Then, in technology shown in Figure 19, interlayer dielectric 9 is formed at the top of the groove 6 that forms on the surface from N+ emitter layer 3.Then, in technology shown in Figure 20, on the surface of N-substrate 1, form flat region 2FR and two emitter electrodes 10 that side diffusion district 2SDR1,2SDR2 are connected with P base layer 2.Then, in technology shown in Figure 21, on the 1LS of the back side of N-substrate 1, form negative electrode N+ layer 4.Then, in technology shown in Figure 22, on the 1LS of the back side of N-substrate 1, form collector region P+ layer 5.Then, by forming collector electrode (not shown) on the 1LS overleaf, can access the IGBT device of the diode-built-in haplotype of Fig. 1.

(example 6)

Figure 23～Figure 29 is the sectional arrangement drawing of device configuration that each technology of the IGBT device that is used for shop drawings 2 is shown.In technology shown in Figure 23, at first, prepare to become the N type silicon substrate 1 of N-substrate.Then, in technology shown in Figure 24, on the surface of N-layer 1, optionally form P base layer 2.Then, in technology shown in Figure 25, in the middle body of P base layer 2, optionally form emitter region 3.Then, in technology shown in Figure 26, formation arrives the 1st groove 6 of N-substrates 1 and the 2nd groove (secondary trenches) 12 that the P base layer 2 from the end in the side diffusion district of P base layer 2 arrives N-substrates 1 from N+ emitter layer 3, forms dielectric film 7 in the inside of two grooves 6,12.Then, in technology shown in Figure 27, form polysilicon film,, in two grooves 6,12, form polysilicon 8 by this film is corroded as conductive materials.Then, in technology shown in Figure 28, interlayer dielectric 9 is formed at the top of the main line 6 that forms on the surface from N+ emitter region 3.Then, in technology shown in Figure 29, form flat region and two emitter electrodes 10 that the side diffusion district is connected with each N+ emitter layer 3, each P base layer 2.Then, identical with example 5, go up overleaf on the basis that sequentially forms collector region P+ layer and negative electrode N+ layer, and then go up the formation collector electrode overleaf.

(example 7)

Figure 30～Figure 36 is the sectional arrangement drawing of device configuration that each technology of the IGBT device that is used for shop drawings 7 (example 3) is shown.In technology shown in Figure 30, at first, prepare to become the N type silicon substrate 1 of N-substrate.Then, in technology shown in Figure 31,, optionally form each P base layer 2 making on the surface of N-layer 1 that to be spaced from each other predetermined interval between the adjacent P base layer such.Then, in technology shown in Figure 32, optionally form emitter region 3 at the middle body of each P base layer 2.Then, in technology shown in Figure 33, form the main line 6 that arrives N-substrates 1 from N+ emitter layer 3, on the surface of the inside of groove 6 and N-layer 1, form dielectric film all sidedly.Then, in technology shown in Figure 34, on dielectric film, form polysilicon film,, only in groove 6, form polysilicon 8 by this polysilicon film corrosion as conductive materials.Then, in technology shown in Figure 35, remove on the surface that is positioned at N-layer 1 and the lip-deep dielectric film of P base layer 2, form interlayer dielectric 9 on the top of groove 6.On this basis, by from the surface of the N-floor 1 that exposes that is clipped in the middle by adjacent side diffusion district the conductive materials of formation schottky junctions such as platinum being imported in the N-floor 1 under this surface, form by the silicide film 13 of this conductive materials with the silicon atom generation.This silicide film 13 and under the interface of N-layer 1 constitute schottky junction.Perhaps, by surface from the N-floor 1 that exposes that is clipped in the middle by adjacent side diffusion district, inject boron with low-doped amount in the N-layer 1 under this surface, carry out the heat treatment about 400 ℃ then, form the extremely thin P-layer 13 of low concentration in the N-layer 1 under this surface.This shallow P-layer 13 and under the interface of N-layer 1 also constitute and the similar PN junction face of schottky junction.On this basis, then, in technology shown in Figure 36, form the emitter electrode 10 that is connected with the various piece of N+ emitter layer 3, film 13 and P base layer 2 with aluminium.Then, identical with example 5, on the back side of N-layer 1, sequentially form collector region P+ layer and negative electrode N+ layer, on this basis, on the back side of N-layer 1, form collector electrode.

In the example 5～6 of above-mentioned manufacture method, on the basis of initial formation collector region P+ layer on the back side of N-layer 1, then, form negative electrode N+ layer, and,, also can access same structure and action effect even form arbitrary layer at first for two-layer formation order.

And then, in above-mentioned manufacture method, after the formation of the emitter electrode 10 of a surperficial side, go up overleaf and form collector region P+ layer and negative electrode N+ layer, otherwise and also can before forming emitter electrode 10, form collector region P+ layer and negative electrode N+ layer overleaf, also can access same structure and action effect certainly in this case.

(example 8)

If characteristic point with reference to this example of Figure 42 diagrammatic illustration, then its core is to possess (1) and forms in Semiconductor substrate 1 and have with the 1st interarea 1US almost parallel and constitute the 1st semiconductor layer (P base layer) 2 of the 2nd conduction type (being the P type) of the 1st bottom surface 2BS of general planar face here from the 1st interarea 1US of Semiconductor substrate 1, (2) the 1st interarea 1US from Semiconductor substrate 1 forms in Semiconductor substrate 1, when having with the 1st interarea 1US almost parallel and formation general planar face, shallow the 2nd bottom surface 14BS than the 1st bottom surface 2BS (owing to being that therefore the 2nd bottom surface 14BS is inevitable superficial for low concentration), and, the 5th semiconductor layer (the P-layer of diode-built-in unit) 14 with the 2nd conduction type of the 1st main electrode (emitter electrode) 14 conductings, (3) form in Semiconductor substrate 1 from the 1st interarea 1US, and when the 1st semiconductor layer 2 and the 5th semiconductor layer 14 be separated from each other, has the main line 6 of the bottom 6B more shallow than the 1st bottom surface 2BS.And, its core is that the 2nd bottom surface 14BS of (4) the 5th semiconductor layers 14 is relative with the 4th semiconductor layer (N+) 4 through Semiconductor substrate 1, when 3 layers 14,1,4 constituted the PIN diode of non-internally-arranged type, the impurity concentration of the 5th semiconductor layer 14 (P-) was lower than the impurity concentration (impurity concentration of＜the 3 semiconductor layer (P+) 5) of the 1st semiconductor layer (P) 2.Among Figure 42, the various piece key element of the structure of illustrative IGBT unit does not change among other each point and Fig. 5 for example.

As shown in figure 42, the anode P-layer 14 of the insulated gate of IGBT unit structure part and even MOS structure part (the mainly zone that is made of inscape 2,3,7,8) and internally-arranged type diode is physically separated mutually by main line 6 in the 1st interarea 1US.Promptly, the MOS structure part of IGBT is formed in the mesa region of the Semiconductor substrate 1 that is clipped in the middle by main line 6, on the other hand, the anode P-layer 14 of internally-arranged type diode is formed on two main lines 6 is present between the inner mutual adjacent mesa region.And the impurity concentration of anode P-layer 14 is set at lower than the impurity concentration (P) of the P base layer 2 of the MOS structure part of IGBT.

As mentioned above, in this example, the MOS structure part of IGBT is separated from each other through main line 6 with the anode P-layer 14 of internally-arranged type diode, and the anode P-layer 14 of internally-arranged type diode is compared with the P base layer 2 of MOS structure part and is set at low concentration layer.Therefore, the structure in the past of concentration (P) that is equal to the P base layer 2 of MOS structure part with the concentration of the anode layer of diode is compared, diode region when the inhibition diode is in conducting from the internally-arranged type diode, that is, and the injection rate in the hole of anode P-layer 14.Thereby, by such according to the hole that suppressed injection rate injection and even the diffusion of comparing with structure in the past of impurity concentration difference to N-layer 1, near the anode of diode in the district carrier density also reduces than structure in the past, its as a result the restoring current of diode also reduce (advantage 1) than structure in the past.If repeated description, then because the hole is low to the injection efficiency of the Semiconductor substrate 1 of diode, therefore the quantity from the 5th semiconductor layer 14 injected holes reduces when diode action, has improved recovery characteristics.

In addition, in the 1st interarea 1US, can freely set the area ratio that MOS constructs partly and the diode region of diode is occupied respectively of IGBT according to the formation position of main line 6.Therefore, can set best area ratio (advantage 2).

And then, as has been described, owing to MOS structure part is separated with diode region 14, so in the part of the Semiconductor substrate 1 of the 1st interarea 1US one side, can separate the action of IGBT element and the action of diode corresponding with it with main line 6.Such separation is configured in the course of action of diode and is applying on the gate electrode 8 under the situation of conducting voltage, also brings the such advantage (advantage 3) of misoperation that can prevent device.

(example 9)

If characteristic point with reference to Figure 43 narration this example different with two kinds of structures of Fig. 5 and Figure 42, then possessing (1) as its core forms by the inside of the 1st semiconductor layer 2 towards Semiconductor substrate 1 from the 1st interarea 1US, the 1st side diffusion district 2SDR1 and the flat region 2FR of the 1st semiconductor layer 2 are separated from each other, main line 6 with bottom 6B darker than the 1st bottom surface 2BS, (2) form in Semiconductor substrate 1 from the 1st interarea 1US, and other trap floor WL of 2nd conduction type (here be P type) relative with the 1st side diffusion district 2SDR1, (3) in the 1st interarea 1US, the regional 1USS that is clipped in the middle from the side diffusion district 2SDR2 by the 1st side diffusion district 2SDR1 and adjacent trap floor WL forms in Semiconductor substrate 1, combine with the 1st interarea side part of the side diffusion district 2SDR2 of the 1st interarea side part of the 1st side diffusion district 2SDR1 and trap floor WL, have with the 1st interarea 1US almost parallel and when constituting the general planar face time than shallow the 2nd bottom surface 14BS of the 1st bottom surface 2BS, also with the 5th semiconductor layer (P-) 14 of upper surface the 2nd conduction type of the 1st main electrode 10 conductings, and, the 2nd bottom surface 14BS of (4) the 5th semiconductor layers 14 is relative with the 3rd semiconductor layer (N+) 4 through the body portion of Semiconductor substrate 1, and the impurity concentration of the 5th semiconductor layer 14 (P-) is lower than the impurity concentration (P) of the 1st semiconductor layer 2.Among Figure 43, other each point for example with Fig. 5 in each inscape of structure of illustrative IGBT unit do not change.

As shown in figure 43, in this example, extend to the table section of diode at the 1st side diffusion district 2SDR1 that has separated with flat region 2FR with main line 6, its result, the 1st interarea side part and the 5th semiconductor layer 14 physical bond (its result, this layer 14,2SDR1 conduct mutually) that are set at than flat region 2FR and the 1st side diffusion district 2SDR1 low concentration P-of this zone 2SDR1.Even this point with adjacent cells in the relation in side diffusion district of well region WL in also identical.

According to above structure, this example (1) not only plays the action effect identical with the example that exists for cause 8 of the 5th semiconductor layer 14, (2) still reduce corresponding from the 1st side diffusion district 2SDR1 in the diode region to the injection rate of Semiconductor substrate 1 with the hole, near the carrier density in anode region is reduced, seek the further reduction of restoring current, thus, can more be difficult to cause oppositely withstand voltage reduction, and, (3) owing to compare with the structure of Figure 42, two space segments of the side diffusion district 2SDR2 of the 1st side diffusion district 2SDR1 in the ratio minimizing diode region that the 5th semiconductor layer 14 occupies in diode region and adjacent well region WL thereof, therefore the hole also has to the minimizing of its occupied area relatively also reduce to the injection rate of Semiconductor substrate 1 from the 5th semiconductor layer 14, thereby, can seek the further reduction of restoring current.In addition, this example (4) also plays following distinctive action effect.Promptly, in this example, as shown in figure 43, the structure division of the bottom surface 2BS1 of the 1st side diffusion district 2SDR1 from diode region and the side of main line 6 is to the distance of the bottom 6B of main line 6, that is, the overhang AP of the bottom 6B of main line 6 compares especially few with the situation of Figure 42.Thereby, have the withstand voltage advantage that is easier to stably keep diode than the situation of Figure 42.(5) and then, if according to this structure, then increased the 1st semiconductor layer 2 degree more than needed on making.

(example 10)

The insulated-gate semiconductor device of this example has improved the insulated-gate semiconductor device of the illustrative example 8 of Figure 42, its main points of improving point are as shown in figure 44, zone that is clipped in the middle by adjacent main line 6 in Figure 42 and the regional integration that is provided with the 1st semiconductor layer 2 are replaced into " by the 6th semiconductor layer 15 of the 1st conduction type (being the N type here) with impurity concentration (N) higher than the impurity concentration (N-) of Semiconductor substrate 1 and be arranged on the dual structure of the 1st semiconductor layer 2 formations of the 2nd conduction type (being the P type) directly over it here ".In other words, be characterised in that disposed have with the 1st bottom surface 2BS of the 1st semiconductor layer 2 and under the 6th semiconductor layer 15 this point of the 1st conduction type of the high impurity concentration (N) of the ratio substrate doping density (N-) of part interlayer of Semiconductor substrate 1.Other each structure and the corresponding structure in the example 8 do not change.Thereby, in two examples,, in Figure 44, quote corresponding reference symbol among Figure 42 and Fig. 5 for the reference symbol of common various piece.

Promptly, this device possesses (1) as its core and forms in Semiconductor substrate 1 from the 1st interarea 1US of Semiconductor substrate 1, has the 1st semiconductor layer 2 of the 2nd conduction type that constitutes the 1st bottom surface 2BS of general planar face with interarea 1US almost parallel, (2) form in Semiconductor substrate 1 from the 1st interarea 1US, when the 1st semiconductor layer 2 and the 6th following semiconductor layer 15 being clipped in the middle with each side, two main lines 6 with mutual aligning of the bottom 6B darker than the 3rd bottom surface 15BS of the 1st bottom surface 2BS and the 6th semiconductor layer 15, (3) have the 1st bottom surface 2BS of formation the 1st semiconductor layer 2 and the surface at interface, the 3rd relative with this interface and more shallow bottom surface 15BS than the bottom 6B of main line 6, the 6th semiconductor layer 15 of the 3rd side 15SS1 that is clipped in the middle by above-mentioned interface and the 3rd bottom surface 15BS and the 1st conduction type (N) of the 4th side 15SS2.And, the 1st side 3S1 of the 2nd semiconductor layer 3, combine with the above-mentioned side of main line 6 with each of the 3rd side 15SS1 of the side of the 1st semiconductor layer 2 of 3 lower surface 3BS combination on the 2nd semiconductor and the 6th semiconductor layer 15, and then, the impurity concentration of the 6th semiconductor layer 15 (N) is than impurity concentration (N-) height of Semiconductor substrate 1, and the impurity concentration (N+) of ratio the 4th semiconductor layer 4 is low.

In addition, different with the illustration of Figure 44, the 3rd bottom surface 15BS of the 6th semiconductor layer 15 also can be than the bottom 6B dark (degree of depth of the degree of depth of the 3rd bottom surface 15BS＞bottom 6B) of main line 6.In such variation, can access action effect described later too, thereby, confirmed experimentally that by inventors this variation is no problem technically.And the structure of the 3rd bottom surface 15BS among Figure 44 is an example, does not exist the 3rd bottom surface 15BS to be set in the certainty (this point is also set up) of the position more shallow than the bottom 6B of main line 6 in each variation described later.

New the 6th semiconductor layer (N+ layer) 15 that adds plays following two action effects in this example.The 1st is to contribute aspect the conducting voltage that reduces the IGBT element.Promptly, the 6th semiconductor layer that concentration ratio substrate concentration (N-) is high (N layer) 15 act as when the IGBT element is in conducting state, prevent that the 3rd semiconductor layer injected holes of one side from the back side from arriving the potential barrier of emitter electrode 10 through the P base layer 2 of IGBT element, its result, under the conducting state of IGBT element, the above-mentioned hole of being injected is stored in the 6th semiconductor layer (N layer) 15 under the 3rd bottom surface 2BS of P base layer 2.Follow the storage in this hole, the electron concentration in the 6th semiconductor layer under the conducting state of IGBT element (N layer) 15 also increases.Thereby the conducting resistance under the IGBT element conductive state reduces, and further reduces the conducting voltage of IGBT element.Its 2nd action effect (advantage) is by there is the 6th semiconductor layer (N+) 15 as potential barrier, under the conducting state of diode-built-in unit, with the 5th semiconductor layer 14, can suppress injection from the excess holes of the P base layer 2 of the IGBT element of P anode layer a part of effect of playing this diode.Be accompanied by the injection rate that suppresses this hole, can further promote the reduction of the restoring current of diode.In addition, even the 2nd advantage is to replace IGBT to use the advantage that also can set up under the situation of vertical MOS FET.

Such as has been described, in the unit structure of Figure 44, also identical with Figure 42, be provided with " forms towards Semiconductor substrate 1 in from the 1st interarea 1US of Semiconductor substrate 1; have main line 6 is clipped in the middle of it side 14S1 with the relative side in above-mentioned side of the 1st side 3S1 of the 2nd semiconductor layer 3 and the 1st semiconductor layer 2; possess the 2nd bottom surface 14BS more shallow in the time of with the 1st interarea 1US almost parallel formation general planar face than the 3rd bottom surface 15BS, the impurity concentration that the while combines with the 1st main electrode 10 in the 1st interarea 1US than the impurity concentration (P) of the 1st semiconductor layer 2 greatly " the 5th semiconductor layer 14 of the 2nd conduction type.Thereby, in this example, can access the action effect of narrating for the structure of Figure 42 too.Thereby the coincidence by the low concentration (P-) of the 5th semiconductor layer 14 is changed the action effect of having narrated of generation and passed through above-mentioned the 2nd advantage of configuration the 6th semiconductor layer 15 generations can reach the further reduction of the restoring current of diode.

(variation 1 of example 10)

Figure 45 illustrates the sectional arrangement drawing of the IGBT unit of this variation.As from the structure of Figure 45 clear and definite, the characteristic point of this variation is to add for the structure of the illustrative example 9 of Figure 43 the distinctive structure (disposing the 6th semiconductor layer 15) of the example of having narrated 10.

Thus, if according to this variation, the action effect of then can be equally in each of example 9 and example 10, having narrated to performance.

(variation 2 of example 10)

Figure 46 illustrates the sectional arrangement drawing of the IGBT unit of this variation.As from the structure of Figure 46 clear and definite, the characteristic point of this variation is to have added for the illustrative structure of the Fig. 5 in the example 2 the distinctive structure (disposing the 6th semiconductor layer 15) of the example of having narrated 10.

Thus, if according to this variation, then can bring into play the action effect of in each of example 2 and example 10, narrating simultaneously.

(variation 3 of example 10)

Figure 47 illustrates the sectional arrangement drawing of the IGBT unit of this variation.As from the structure of Figure 47 clear and definite, the characteristic point of this variation is to have added for the illustrative structure of Fig. 6 of example 2 the characteristic structure (disposing the 6th semiconductor layer (N) 15) of the example of having narrated 10.

As having narrated among Fig. 6 of example 2, secondary trenches 12 is the bound fraction of the bottom surface 2BS1 of the 1st side diffusion district 2SDR1 in the 1st interarea 1US with the bottom surface 2BS1 of the side diffusion district 2SDR1 of trap floor WL, prolongs the 1st side diffusion district 2SDR1 of formation and the side diffusion district 2SDR1 of trap floor WL is separated from each other in Semiconductor substrate 1 from the near zone of this bound fraction.

Thus, if according to this variation, the action effect of having narrated in Fig. 6 that then can bring into play jointly and each of example 10 at example 2.

(variation 4 of example 10)

Figure 48 illustrates the sectional arrangement drawing of the IGBT unit of this variation.As from the structure of Figure 48 clear and definite, the characteristic point of this variation is to be suitable for for the illustrative structure of the Fig. 7 in the example 3 the characteristic structure (disposing the 6th semiconductor layer (N) 15) of the example of having narrated 10.

Thus, if according to this variation, the action effect of having narrated in Fig. 7 that then can bring into play jointly and each of example 10 at example 3.

(variation 5 of example 10)

The characteristic point of this variation is for the structure of diagram 81 secondary trenches 12 to be set at least also.In other words, the characteristic point of this variation is as Figure 49 is illustrative, for Fig. 8 in the example 3 or the illustrative structure of Fig. 9, is suitable for the characteristic structure (the 6th semiconductor layer (N) 15 is set) of the example of having narrated 10.Each secondary trenches 12 among Figure 49 is extended from district between the 1st interarea 1US trap, possesses the bottom 12B of the part of the Semiconductor substrate 1 that is arranged in film 13 belows.

Thus, if according to this variation, the action effect of having narrated in each of Fig. 8 that then can bring into play jointly etc. and example 10 at example 3.

(variation 6 of example 10): Figure 50

The characteristic point of this variation is to be suitable for the structure of narrating for Figure 41 (dead space that is clipped in the middle by main line and secondary trenches is set) for the structure (variation 4) of diagram 8.Figure 50 illustrates an example of this suitable example.

Promptly, this IGBT unit possesses (1) at least as its distinctive inscape and forms in Semiconductor substrate 1 from the 1st interarea 1US, when having than the dark bottom 12B of the 3rd bottom surface 15BS, the secondary trenches 12 adjacent with main line 6, (2) dielectric film 7 of other that on the bottom of secondary trenches 12 12B and side thereof, whole forms, (3) be clipped in the middle by the side of the side of main line 6 and secondary trenches 12, upper surface 14FRUS with the 1st interarea 1US that is positioned at Semiconductor substrate 1, than the 1st bottom surface 2BS flat region 14FR dark and the 2nd conduction type (P type) of the 3rd shallow bottom surface 14FRBS than the 3rd bottom surface 15BS, (4) whole interlayer dielectric 14IF that ground forms on the upper surface 14FRUS of flat region 14FR, (5) side from the 1st interarea 1US along main line 12 forms towards the inside of Semiconductor substrate 1, it is relative with flat region 14FR to pass through secondary trenches 12 therebetween, and in the 1st interarea 1US, have the upper surface that combines with the 1st main electrode 10, and has the 1st side diffusion district 14 of the 2nd conduction type (P type) of deepening gradually smoothly and possessing the bottom surface 14BS of the depth capacity more shallow than the bottom 12B of secondary trenches 12.

Thus, if according to present embodiment, when then can similarly bring into play the action effect that the Figure 48 for example 3 narrated, can also obtain the action effect of narrating for the variation of Figure 41.If the latter is repeated to record and narrate, then because upper surface 14FRUS and the covering of two side of impurity range (flat region) 14FR of the P type that surrounds with two grooves 6,12 with all use whole of dielectric film 14IF, 7IF, be in the state with the 1st main electrode 10 electric insulations, therefore can not carry out all actions as the part of diode the earliest.That is, flat region 14FR watches the state that is in the dead spaceization from the viewpoint of the action of diode.Thereby the hole is fewer to the injection rate of Semiconductor substrate 1 inside from the p type island region of diode-built-in unit, and near the carrier density the anode descends, and the restoring current of diode can be lower.

(variation 7 of example 10): Figure 51

The correcting structure of relevant Figure 50 of this variation (variation 6) as shown in Figure 51 of one example, extends to form in the flat region 14FR that is clipped in the middle by two grooves 6,12 among Figure 50 as an end of the 6th semiconductor layer 15 of N type layer.That is, this variation is for the structure of variation 6, also possesses from the 7th semiconductor layer 15E of whole the 1st conduction type (N type) that forms towards the inside of flat region 14FR of the 4th bottom surface 14FRBS of the flat region 14FR of Figure 50.Thereby, the flat region 14FR of Figure 50 is shown in Figure 51, had from side one side of main line 6 towards the side of secondary trenches 12 side gradually and the 7th semiconductor layer of the thickness that reduces continuously (region of elongation of the 6th semiconductor layer 15) 15E by (1), (2) are made of the dead space 14SR of the 2nd conduction type (P type) that the 7th semiconductor layer 15E and the 1st interarea 1US are clipped in the middle.

Dispose the reasons are as follows of this 7th semiconductor layer 15E.That is, only in that being clipped in the middle, the 1st semiconductor layer 2 forms the 6th semiconductor layer 15 of N type between two main lines 6 mutually aiming at, on making and very difficult in the practicality.For this reason, produced the interior situation that forms the 6th semiconductor layer 15 in zone that main line 6 arrives the P type of crossing.This is because by form the N layer in plasma injection technology partly etc., then, and the N type diffusion of impurities of injecting by making, formation the 6th semiconductor layer 15 in the Semiconductor substrate 1 of N-.Thereby the importing position of N layer by the side diffusion phenomenon, not only at depth direction, also forms the N layer at transverse direction when making, and constitutes the 7th semiconductor layer 15E in the part of this transverse direction side diffusion.

Cross main line 6 by the 6th semiconductor layer 15 and be diffused into this 7th semiconductor layer 15E that the p type island region territory forms, when between emitter electrode 10-collector electrode 11, applying under the situation of collector voltage VCE, owing to improve the electric field strength of diode one side in the main line 6, therefore each the withstand voltage reduction that brings IGBT element and diode sometimes.Yet, in this variation, corresponding secondary trenches 12 is set energetically by the outside at main line 6, the existence zone of the 7th semiconductor layer 15E only is limited between two grooves 6,12.Thereby, in this variation, in the side diffusion district 14 of the major part that constitutes the diode-built-in unit, there is not the 7th semiconductor layer 15E at all, thereby compare with the situation of Figure 48 in main line (the 1st groove) 6 only is formed on P type well region, this variation has the advantage of the withstand voltage reduction of forward of the withstand voltage reduction that do not cause the IGBT element and diode.

In addition, if the N floor of the 6th semiconductor layer 15 is crossed secondary trenches (the 2nd groove) 12 and is formed in the side diffusion district 14, then because the main p type island region of diode leaves from the zone 15 that has partly formed the N layer, the concentration of therefore crossing the N floor 15E of concentration ratio between two grooves 6,12 that secondary trenches 12 is formed on the N layer segment in the side diffusion district 14 is low.Thereby, under these circumstances, compare with the situation of Figure 48 in main line (the 1st groove) 6 only is formed on P type well region, we can say also to be difficult to cause above-mentioned withstand voltage reduction.

(variation 8 of example 10): Figure 52

This variation is equivalent to the correction example of the structure of Figure 49 (variation 5), and Figure 52 illustrates an example of its structure.In this variation, under the part of the close main line 6 in the bottom surface 14BS in P type side diffusion district 14, along with the interface of bottom surface 14BS, in Semiconductor substrate 1, form the 8th semiconductor layer 15E of N type, the bottom surface 15EBS of this layer 15E is more shallow than the bottom 6B of main line 6.

In this variation, crossing that the 8th semiconductor layer 15E that main line 6 formed the N layer compares with N layer 15 is low concentration layer, and, on the part owing to the bottom surface 14BS that only is formed on side diffusion district 14, therefore we can say that the influence of the withstand voltage reduction that is caused by the 8th semiconductor layer 15E is smaller.

(example 11)

This example is applicable to the example of having narrated 2 (for example structure of Fig. 5 and Fig. 6), example 4 (for example structure of Figure 12, Figure 13 and Figure 41), example 8 (for example structure of Figure 42) is in each of example 9 (for example structure of Figure 43) and example 10 (for example structure of Figure 44 to Figure 52).

Here, each of Figure 53 and Figure 54 is near the vertical view the some relevant IGBT unit cell with above-mentioned each example.Promptly, 2 Figure 53, each of 54 illustrates the zone (being called the MOS tectonic province) 16 that (1) MOS structure on the 1st interarea 1US of Semiconductor substrate 1 occupies, (2) zone occupied of the main line 6 on the 1st interarea 1US of Semiconductor substrate 1 (is provided with under the situation of secondary trenches 12 in P type well region, be equivalent to main line 6, by two grooves 6, the 12 dead space 14FR that are clipped in the middle, the zone that 14SR and secondary trenches 12 are occupied) (being called trench area) 6R, the figure on the 1st interarea 1US of the Semiconductor substrate 1 that zone (the being called the diode district) 17R that (3) are occupied in diode-built-in unit on the 1st interarea 1US of Semiconductor substrate 1 constitutes.

Shown in Figure 53 and Figure 54, when MOS tectonic province 16R and diode region 17R clamp trench area 6R therebetween, arrange alternately along the extension of the 3rd direction D3 ribbon and along the 1st direction D1.

Like this, form two regional 16R, 17R by ribbon ground alternatively, this device is in the time spent of doing of playing insulated gate transistor or diode, and in Semiconductor substrate 1, each that can make insulated gate transistor and diode is moved almost evenly.

In addition, in Figure 53 and Figure 54, can all be set at arbitrary value to the area of the area of MOS tectonic province 16R and diode district 17R.

In addition, in order to promote the operating characteristics of insulated gate transistor (IGBT etc.), particularly promote the reduction of its turn-on voltage, it is effective reducing the area that the P type layer (anode region) of the diode on the 1st interarea 1US be formed on Semiconductor substrate 1 occupies on the 1st interarea 1US.In this case, the restoring current of diode also reduces.If consider such viewpoint, the structure that then forms film 13 below diode district 17R (for example, Figure 12, Figure 13, the illustrated structure of Figure 41, Figure 48-Figure 52) in, can adopt the area Figure 54 illustrative figure bigger of diode district 17R than the area of MOS tectonic province 16R, its result, owing to can set the area that the side diffusion district of P type occupies in the 1st interarea, therefore can make the operating characteristics of insulated gate transistor better littlelyr.In this sense, adopt the figure of Figure 54 enough synthetically to play favourable effect for improving performance.

(example 12)

This example is applicable to the example of having narrated 2 (for example structure of Fig. 5 and Fig. 6), example 4 (for example structure of Figure 12, Figure 13 and Figure 41), example 8 (for example structure of Figure 42) is in each of example 9 (for example structure of Figure 43) and example 10 (for example structure of Figure 44 to Figure 52).

Here, each of Figure 55 and Figure 56 is near the vertical view the some relevant IGBT unit cell with above-mentioned each example.In addition, in the figure of Figure 56, compare with the figure of Figure 55, the allocation position of MOS tectonic province 16R and diode district 17R is set on the contrary.Promptly, two Figure 55,56 each in, the either party of MOS tectonic province 16R and diode district 17R is square, trench area 62 is integrally surrounded its marginal portion, and then the opposing party of MOSFET channel region 16R and diode district 17R integrally surrounds the marginal portion of trench area 6R.

By adopting such graphical configuration, compare with the banded figure of Figure 53 and Figure 54, can dispose the raceway groove of insulated gate transistor two-dimensionally, can use this raceway groove effectively.

Wherein, when adopting each structure of Fig. 5 and Figure 56, shown in Figure 57, the connection with groove time that connects each groove on square is set, shown in Figure 58, each surface that need utilize above-mentioned connection groove to be provided for making in trench area to surround the above-mentioned side zone around it is the such connecting elements of for example polysilicon layer 18 of electrical connection mutually.

(example 13)

Figure 59 to Figure 66 is the sectional arrangement drawing of the device configuration in each operation stage when the semiconductor device of making example 8 (Figure 42) is shown.At first, in the technology of Figure 59, prepare to become the N type silicon substrate of N-substrate 1.In the technology of the Figure 60 that follows, on the surface of N-substrate 1, optionally form P base layer 2.In the technology of the Figure 61 that follows, on the surface of P base layer 2, optionally form N+ emitter region 3.In the technology of the Figure 62 that follows, on the surface of the N-substrate 1 between the adjacent P base layer 2, optionally form anode P-layer 14.In the technology of the Figure 63 that follows, form the groove (main line 6) of 3 arrival N-substrates 1 from the N+ emitter region.Whole ground forms dielectric film 7 in the inside of each groove 6.In the technology of the Figure 64 that follows, form polysilicon film as conductive material, then by corrosion, form the polysilicon electrode layer 8 of the inside of each groove 6 of filling.In the technology of the Figure 65 that follows, form interlayer dielectric 9 top of each groove 6 that forms on surface from N+ emitter region 3.In the technology of the Figure 66 that follows, form and N+ emitter region 3 emitter electrode 10 that P base layer 2 and anode P-layer 14 connect.Then, identical with example 5, by forming collector region P+ layer 5 on the back side of N-substrate 1, negative electrode N+ layer 4 and collector electrode 11 obtain having the semiconductor device of the structure of Figure 42.

(example 14)

Figure 67 to Figure 74 is the sectional arrangement drawing of the device configuration in each operation stage when the semiconductor device of the variation 4 (Figure 48) of making example 10 is shown.At first, in the technology of Figure 67, prepare to become the N type silicon substrate of N-substrate 1.In the technology of the Figure 68 that follows, on the surface of N-substrate 1, optionally form N layer 15.In the technology of the Figure 69 that follows, on the surface of N-substrate 1, optionally form the P base layer, make the N layer 15 that forms towards inside from the surface of N-substrate 1 surround.In the technology of the Figure 70 that follows, on the surface of P base layer, optionally form emission N+ layer 3.In the technology of the Figure 71 that follows, a part of removing emission N+ layer 3 is such, forms the groove (main line) 6 that arrives N-substrate 1 inside from emission N+ layer 3, and whole ground forms dielectric film 7 in the inside of groove 6.In the technology of the Figure 72 that follows, form polysilicon film as conductive material, then by corrosion, form the polysilicon electrode layer 8 of the inside of each groove 6 of filling.In the technology of the Figure 73 that follows, form interlayer dielectric 9 on the top of each groove 6.In the technology of the Figure 74 that follows, form the emitter electrode 10 that is connected with N+ emitter region 3, P base layer 2 and side diffusion district, P base 14.If before the formation of this electrode 10, form the material that platinum etc. constitutes schottky junction, then shown in Figure 74, can form schottky junction 13.Then, identical with example 5, by forming collector region P+ layer 5 on the back side of N-substrate 1, negative electrode N+ layer 4 and collector electrode 11 can obtain having the semiconductor device of the structure of Figure 48.

(the common variation in each example)

In addition, in the example in each example 1～14, recorded and narrated the IGBT device of N raceway groove, and, also can be suitable for the technical characterictic in each example 1～7 certainly for the IGBT device of P raceway groove.

In addition, such as has been described, in the vertical MOS FET of N raceway groove or P raceway groove device (trench MOSFET of diode internally-arranged type), also can be suitable for the technical characterictic in each example.In this case, do not need the 3rd semiconductor layer 5, whole ground forms the 4th semiconductor layer 4 on the 2nd interarea 1LS of Semiconductor substrate 1.Figure 75 and Figure 76 illustrate the present invention are useful in typical example in the vertical MOS FET device.

Below at length open and recorded and narrated example of the present invention, above record illustration can be suitable for situation of the present invention, but the present invention is not limited to these situations.That is, in the scope that does not break away from, can consider each kind correction or variation for situation about being recorded and narrated from the scope of the invention.

Power semiconductor of the present invention, that is, the insulated gate transistor of diode internally-arranged type can be utilized as power converter apparatus on industry, for example the FWD internally-arranged type switch element in the inverter circuit of drive motors even load.The block diagram of Figure 37 shows for the application examples of such three phase alternating current motor with inverter circuit.

Claims (3)

1. insulated gate transistor possesses:

Semiconductor substrate with the 1st conduction type of the 1st interarea and the 2nd interarea;

In above-mentioned Semiconductor substrate, form the 1st semiconductor layer of the 2nd conduction type of trap shape from above-mentioned the 1st interarea of above-mentioned Semiconductor substrate, the 1st semiconductor layer has the 1st side diffusion district, 2nd side diffusion district and the flat region above-mentioned 1st side diffusion district and above-mentioned 2nd side diffusion district between relative with above-mentioned the 1st side diffusion district, and above-mentioned flat region has the 1st bottom surface that constitutes with the tabular surface of above-mentioned the 1st main surface parallel;

From the main line that above-mentioned the 1st interarea forms towards the inside of above-mentioned Semiconductor substrate by above-mentioned the 1st semiconductor layer, this main line is separated from each other above-mentioned the 1st side diffusion district and has than dark bottom, above-mentioned the 1st bottom surface with above-mentioned flat region;

The dielectric film that on the whole above-mentioned bottom of above-mentioned main line and side, forms;

The whole face that the is formed on above-mentioned dielectric film control electrode of the above-mentioned main line of filling that comes up;

The 2nd semiconductor layer of above-mentioned the 1st conduction type that forms in above-mentioned the 1st semiconductor layer from above-mentioned the 1st interarea, the 2nd semiconductor layer have the upper surface that is positioned on above-mentioned the 1st interarea, relative with above-mentioned upper surface and constitute the lower surface of bottom and the 1st and the 2nd side that is clipped in the middle and is aimed at mutually by above-mentioned upper surface and above-mentioned lower surface;

In above-mentioned Semiconductor substrate, form and the trap floor of above-mentioned 2nd conduction type relative from above-mentioned the 1st interarea with above-mentioned the 1st side diffusion district;

From the 5th semiconductor layer of above-mentioned the 2nd conduction type that forms in above-mentioned Semiconductor substrate from the zone that is clipped in the middle by above-mentioned the 1st side diffusion district and the side diffusion district of above-mentioned trap floor in above-mentioned the 1st interarea, combine with the part in the above-mentioned side diffusion district of the part in above-mentioned the 1st side diffusion district and above-mentioned trap floor, the 5th semiconductor layer has formation and the tabular surface of above-mentioned the 1st main surface parallel and 2nd bottom surface more shallow than above-mentioned the 1st bottom surface;

The 4th semiconductor layer of above-mentioned the 1st conduction type that in above-mentioned Semiconductor substrate, forms from above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate;

Be formed on the above-mentioned upper surface of above-mentioned the 2nd semiconductor layer and the 1st main electrode on the upper surface of above-mentioned the 5th semiconductor layer;

The 2nd main electrode that is formed on above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate and conducts with above-mentioned the 4th semiconductor layer,

Above-mentioned the 1st side of above-mentioned the 2nd semiconductor layer combines with the above-mentioned side of above-mentioned main line,

Above-mentioned the 2nd bottom surface of above-mentioned the 5th semiconductor layer is relative with above-mentioned the 4th semiconductor layer across above-mentioned Semiconductor substrate,

The impurity concentration of above-mentioned the 5th semiconductor layer is lower than the impurity concentration of above-mentioned the 1st semiconductor layer.

2. insulated gate transistor according to claim 1 is characterized in that:

Ribbon ground is mutual to be formed MOS be configured in the diode district that the MOS tectonic province that occupies on above-mentioned the 1st interarea and diode occupy on above-mentioned the 1st interarea.

3. insulated gate transistor according to claim 1 is characterized in that:

Also possess form in above-mentioned Semiconductor substrate from above-mentioned the 2nd interarea of above-mentioned Semiconductor substrate, with above-mentioned the 4th semiconductor layer in abutting connection with and the 3rd semiconductor layer of above-mentioned the 2nd conduction type that conducts with above-mentioned the 2nd main electrode.

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