JP2017076803A - Semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor element hardly generating noise.SOLUTION: In a semiconductor element 1, an n-type drift layer 11 as a second semiconductor layer is provided on an n-type drain layer 10 as a first semiconductor layer. In an element region 90, a p-type base layer 12 as a third semiconductor layer is selectively provided on a surface of the n-type drift layer. On a surface of the p-type base layer, an n-type source layer 13 as a fourth semiconductor layer is selectively provided. Along the outermost periphery of the element region, a p-type layer 12a is provided on a surface of the n-type drift layer. A first gate insulating film 30 as a first insulating film is provided on the n-type drift layer, the p-type base layer, the n-type source layer, and the p-type layer.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a semiconductor device.

To reduce the size of a power supply circuit such as a switching power supply, it is effective to increase the switching frequency and reduce passive elements such as inductance and capacitance in the power supply circuit. However, when switching frequency is increased, MOSFET (Metal Oxide Semiconductor Fiel
The switching loss of switching elements such as d Effect Transistor and IGBT (Insulated Gate Bipolar Transistor) increases, and the power efficiency of the switching power supply decreases. For this reason, for miniaturization of a power supply circuit such as a switching power supply, it is indispensable to reduce the switching loss while increasing the speed of the switching element.

In MOS gate elements such as MOSFETs and IGBTs used as switching elements, the gate capacity is reduced by shortening the gate length to increase the speed.
However, when the gate capacitance is reduced and the speed is increased, resonance occurs between the parasitic inductance included in the wiring and the switching element capacitance. For this reason, the MO
High frequency noise is generated from the S gate element.

As an example of solving this problem, p under the gate electrode of the MOS gate elements ^- there is a structure in which a shape layer. According to such a structure, the capacitance between the gate and the drain when a high voltage is applied is increased, and the temporal change (dV / dt) of the drain voltage is reduced. This reduces switching noise. However, p under the gate electrode ^- manufacturing process of forming the shape layer is complex. Therefore, there is a lower limit to the cost reduction of the MOS gate element.

Japanese Patent Laid-Open No. 2004-006598

  Embodiments of the present invention provide a semiconductor device that is less susceptible to noise.

The semiconductor device of the embodiment is selectively provided on a surface of the first semiconductor layer of the first conductivity type, the second semiconductor layer of the first conductivity type provided on the first semiconductor layer, and the surface of the second semiconductor layer. Second provided in
A third semiconductor layer of conductivity type, a fourth semiconductor layer of first conductivity type selectively provided on a surface of the third semiconductor layer, the first semiconductor layer, the third semiconductor layer, and the fourth semiconductor layer; A semiconductor layer and a first
A first control electrode opposed via an insulating film, and the second semiconductor in a second region different from the first region electrically connected to the first control electrode and provided with the first control electrode A lead electrode provided on the layer, and a second control electrode and a third control electrode electrically connected to the lead electrode and facing the second semiconductor layer via a second insulating film under the lead electrode When,
The second semiconductor layer, comprising: a first main electrode connected to the first semiconductor layer; and a second main electrode connected to the third semiconductor layer and the fourth semiconductor layer. The third semiconductor layer is not provided on the surface of the second control electrode, and at least a part of the second control electrode,
At least a part of the control electrode is provided below the extraction electrode, and the electrical resistance of the second control electrode is higher than the electrical resistance of the third control electrode.

It is a figure explaining the outline | summary of the semiconductor element which concerns on embodiment. It is a figure explaining the semiconductor element which concerns on a reference example, (a) is principal part sectional drawing of the semiconductor element which concerns on a reference example, (b) is an equivalent circuit schematic of the semiconductor element which concerns on a reference example. It is a figure explaining the effect of the semiconductor element which concerns on embodiment, (a) is principal part sectional drawing of the semiconductor element which concerns on embodiment, (b) is an equivalent circuit schematic of the semiconductor element which concerns on embodiment. It is a principal part top view of the semiconductor element which concerns on a 1st specific example. 4A and 4B are cross-sectional views of main parts of a semiconductor element according to a first specific example, where FIG. 4A is a cross-sectional view taken along the line XX ′ in FIG. 4, FIG. FIG. 5 is a ZZ ′ cross-sectional view of FIG. 4. It is a principal part top view of the semiconductor element which concerns on the 1st modification of a 1st specific example. FIG. 7 is a cross-sectional view of a principal part of a semiconductor element according to a first modification of the first specific example, where (a) is a cross-sectional view taken along line XX ′ of FIG. 6 and (b) is a cross-sectional view taken along line YY ′ of FIG. It is. It is a principal part top view of the semiconductor element which concerns on the 2nd modification of a 1st specific example. FIGS. 9A and 9B are cross-sectional views of main parts of a semiconductor element according to a second modification of the first specific example, where FIG. 8A is a cross-sectional view taken along the line XX ′ in FIG. 8 and FIG. It is. It is a principal part top view of the semiconductor element which concerns on the 3rd modification of a 1st specific example. 10A and 10B are cross-sectional views of main parts of a semiconductor element according to a third modification of the first specific example, where FIG. 10A is a cross-sectional view taken along the line XX ′ of FIG. It is. It is principal part sectional drawing of the semiconductor element which concerns on the 4th modification of a 1st specific example. It is a principal part top view of the semiconductor element which concerns on a 2nd example. FIGS. 14A and 14B are cross-sectional views of main parts of a semiconductor element according to a second specific example, where FIG. 13A is a cross-sectional view taken along the line XX ′ in FIG. 13, FIG. FIG. 14 is a ZZ ′ sectional view of FIG. 13. It is principal part sectional drawing of the semiconductor element which concerns on the 1st modification of a 2nd specific example. It is a principal part top view of the semiconductor element which concerns on the 2nd modification of a 2nd specific example. It is a principal part top view of the semiconductor element which concerns on the 3rd modification of a 2nd specific example. It is principal part sectional drawing of the semiconductor element which concerns on a 3rd example. It is principal part sectional drawing of the semiconductor element which concerns on the 1st modification of a 3rd example. It is principal part sectional drawing of the semiconductor element which concerns on the 2nd modification of a 3rd example.

Hereinafter, embodiments will be described with reference to the drawings. In the embodiment, the same members are denoted by the same reference numerals, and the description of the members having the same reference numerals is omitted as appropriate.

(Outline of the embodiment)
FIG. 1 is a diagram for explaining the outline of the semiconductor element according to the embodiment. FIG. 1 shows a cross section of a semiconductor device 1 according to the embodiment. In semiconductor element 1, cell units including element region 90 and gate pad region 91 shown in FIG. 1 are periodically arranged. Element region 9
0 may be the first region, and the gate pad region 91 may be the second region.

The semiconductor element 1 includes a MOSFET having an upper and lower electrode structure. In the semiconductor element 1, an n-type drift layer 11 as a second semiconductor layer is provided on an n ⁺ -type drain layer 10 as a first semiconductor layer.

In an element region 90 corresponding to the element central portion of the semiconductor element 1, a p-type base layer 12 as a third semiconductor layer is selectively provided on the surface of the n-type drift layer 11. p-type base layer 12
Are selectively provided with an n ^{+ -type} source layer 13 as a fourth semiconductor layer. A p-type layer 12 a is provided on the surface of the n-type drift layer 11 at the outermost periphery of the element region 90. A first gate insulating film 30 as a first insulating film is provided on the n-type drift layer 11, the p-type base layer 12, the n ^{+ -type} source layer 13, and the p-type layer 12a.

Further, in a direction substantially parallel to the principal surface of the ^{n +} -type drain layer 10, ^{n +} -type source layer 1
A first gate electrode 31 as a first control electrode is provided from a part of 3 to a part of the n-type drift layer 11 through a p-type base layer 12 adjacent to the part 3. The first gate insulating film 30 includes the first gate electrode 31, the n ^{+ -type} source layer 13, the p-type base layer 12, and the n-type source layer 13.
And the drift layer 11. That is, the first gate electrode 31 is n
It faces the drift layer 11, the p-type base layer 12, and the n ^{+ -type} source layer 13 via the first gate insulating film 30.

A drain electrode 60 as a first main electrode is connected to the n ⁺ -type drain layer 10.
A contact layer 61 is connected to the n ^{+ -type} source layer 13 and the p-type base layer 12.
A contact layer 62 is connected to the p-type layer 12a. The contact layers 61 and 62 include
A source electrode 63 as a second main electrode is connected. That is, the source electrode 63 is electrically connected to the n ^{+ -type} source layer 13 and the p-type base layer 12 through the contact layers 61 and 62. Source electrode 63 and contact layers 61 and 62, and first gate insulating film 3
A first gate insulating film 30 is provided between 0 and 0.

In the gate pad region 91, a second gate insulating film 40 as a second insulating film is provided on the n-type drift layer 11 and the p-type layer 12a. Furthermore, a gate electrode 41 including a second control electrode and a third control electrode is provided in a direction substantially parallel to the main surface of the n ⁺ -type drain layer 10. As will be described later, at least a part of the second control electrode;
The entire third control electrode is provided under the gate pad electrode 43. Gate electrode 41
The second gate insulating film 40 is interposed between the gate pad electrode 43 and the n-type drift layer 11.
Is provided. The gate electrode 41 is provided under the gate pad electrode 43. The gate electrode 41 is opposed to the drain electrode 60 with the second gate insulating film 40 interposed therebetween.

A contact layer 42 is connected to the gate electrode 41. A gate pad electrode 43 is connected to the contact layer 42. A second gate insulating film 40 is provided between the gate pad electrode 43 and the gate electrode 41 and the contact layer 62.

The gate pad electrode 43 is provided on the n-type drift layer 11 outside the element region 90 in which the first gate electrode 31 is provided. The gate pad electrode 43 is provided on the n-type drift layer 11 in a region different from the region where the first gate electrode 31 is provided. The gate pad electrode 43 is, for example, an extraction electrode for extracting the first gate electrode 31 to the outside of the semiconductor element 1. Under the gate pad electrode 43, the p-type base layer 12 is not provided. That is, the gate electrode 41 is in contact with the n-type drift layer 11 via the second gate insulating film 40.

In the semiconductor element 1, the gate pad electrode 43 is electrically connected to the first gate electrode 31. The gate electrode 41 is electrically connected to the gate pad electrode 43.

With such a structure, the gate-drain capacitance of the semiconductor element 1 is increased, and switching noise is suppressed.

n ⁺ -type drain layer 10, n-type drift layer 11, p-type base layer 12, n ^{+ -type} source layer 13
, And the main component of the p-type layer 12a, for example, contains silicon (Si) as a main component.

The main component of the first gate insulating film 30 is, for example, silicon oxide (SiO ₂ ). The main components of the second gate insulating film 40 are, for example, silicon oxide (SiO ₂ ), silicon nitride (Si ₃ ).
N ₄ ) and the like.

  The main component of the first gate electrode 31 and the gate electrode 41 is, for example, polysilicon.

The main components of the drain electrode 60, the source electrode 63, and the contact layers 42, 61, and 62 are conductive materials such as copper (Cu), tungsten (W), aluminum (Al), and polysilicon doped with impurities. .

  Next, the effect of the semiconductor element 1 will be described.

Before describing the effects of the semiconductor element 1, a semiconductor element 100 according to a reference example will be described.

2A and 2B are diagrams illustrating a semiconductor element according to a reference example. FIG. 2A is a cross-sectional view of a main part of the semiconductor element according to the reference example, and FIG. 2B is an equivalent circuit diagram of the semiconductor element according to the reference example. is there.

The semiconductor element 100 according to the reference example is not provided with the gate electrode 41 described above. In the semiconductor element 100, the gate pad electrode 43 is disposed in the gate pad region 91.
The gate pad electrode 43 is electrically connected to the first gate electrode 31. An insulating film 400 is provided between the gate pad electrode 43 and the n-type drift layer 11. Further, a p-type layer 110 is provided under the gate pad electrode 43. The structure of the semiconductor element 100 other than those described above is the same as that of the semiconductor element 1.

FIG. 2B shows a source electrode 63 (S) and a drain electrode 60 (D) of the semiconductor element 100.
The connection relationship between the first gate electrode 31 (G) and the gate pad electrode 43 (GP) is shown. An external gate resistor Rg is connected to the gate pad electrode 43. The external gate resistance Rg is, for example, a resistance for adjusting the charge / discharge time between the gate and the drain. For example, the higher the external gate resistance Rg is set, the longer the charge / discharge time between the gate and the drain can be made.

As the semiconductor element becomes smaller, the gate length tends to become shorter. Along with this, the facing area between the gate electrode and the drain electrode is reduced, and the gate-drain capacitance (Cgd
) Is smaller. Along with the miniaturization of the semiconductor element, the switching speed is increased.

However, the gate-drain capacitance (Cgd) compared to the drain-source capacitance (Cds).
) Becomes too small, the switching time is determined by the drain-source charge / discharge time, and the gate controllability at the time of switching deteriorates. Thereby, switching noise is likely to be generated from the semiconductor element 100. For example, the temporal change (dVds / dt) of the drain-source voltage cannot be controlled by the internal gate resistance (
Vds: drain-source voltage).

Further, when the gate-drain capacitance (Cgd) is remarkably reduced and switching is performed at high speed, the parasitic inductance included in the wiring outside the element and the switching elements such as the gate-source, gate-drain, drain-source, etc. Resonance may occur between the capacitance. As a result, high-frequency noise may be generated from the semiconductor element 100 during switching.

A method for suppressing the high frequency noise by setting the charge / discharge time between the gate and the drain longer by adjusting the external gate resistance Rg is also conceivable. However, the gate-drain capacitance (Cgd
) Becomes too small, the method of simply adjusting the external gate resistance Rg limits the gate controllability.

3A and 3B are diagrams for explaining the effect of the semiconductor element according to the embodiment. FIG. 3A is a cross-sectional view of a main part of the semiconductor element according to the embodiment. FIG. 3B is an equivalent circuit of the semiconductor element according to the embodiment. FIG.

In the semiconductor element 1, in addition to the first gate electrode 31, a gate electrode 41 is provided below the gate pad electrode 43. A second gate insulating film 40 is provided between the gate electrode 41 and the drain electrode 60. Alternatively, a depletion layer is formed in the semiconductor layer between the gate electrode 41 and the drain electrode 60. Therefore, in the semiconductor element 1, the gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60 in addition to the gate-drain capacitance (Cgd).

Further, in the semiconductor element 1, a high internal gate resistance is generated by electrically connecting the gate electrode 41 that is a planar pattern and the gate pad electrode 43 that is a planar pattern. For example, the gate pad electrode 43 and the gate electrode 41 are not in contact with the entire region where they face each other. The gate pad electrode 43 and the gate electrode 41 are electrically connected through a thin contact layer 42.

The gate electrode 41 includes a second control electrode and a third control electrode. At least a part of the second control electrode and the entire third control electrode are provided below the gate pad electrode 43.
The electric resistance of the second control electrode may be set higher than the electric resistance of the third control electrode. For example, the line width of the second control electrode is made smaller than the width of the third control electrode. As a result, the gate electrode 4
1 has a high internal gate resistance rg.

Thus, in the semiconductor element 1, in addition to the gate-drain capacitance (Cgd),
An internal gate resistance rg corresponding to the amount of the gate electrode 41 and a gate-drain capacitance (Cgd ′) connected to the internal gate resistance rg are applied in parallel between the gate pad electrode 43 and the drain electrode 60. As a result, the time constant between the gate and the drain of the semiconductor element 1 is larger than that of the semiconductor element 100. As a result, the switching noise of the semiconductor element 1 is suppressed as compared with the semiconductor element 100.

In addition, according to the semiconductor element 1, the gate-drain capacitance increases without increasing the pitch of the first gate electrodes 31. Therefore, in the semiconductor element 1, the channel density per unit area in the element region 90 does not decrease, and the on-resistance per unit area does not increase. Further, the gate electrode 41 is disposed under the gate pad electrode 43. Therefore, the element area of the semiconductor element 1 does not increase.

Regarding the gate-drain capacitance (Cgd ′) under the gate pad electrode 43, Cgd ′ can be appropriately adjusted by changing the contact area between the gate electrode 41 and the second gate insulating film 40. Therefore, the degree of freedom in designing the gate-drain capacitance in the semiconductor element 1 is increased as compared with the semiconductor element 100.

Moreover, in the semiconductor element 1, the manufacturing process which forms a p < ^- > type layer under the gate electrode mentioned above is not required. The patterning of the gate electrode 41 can be performed in the same manufacturing process as the patterning of the first gate electrode 31. For example, by using a mask that combines the pattern shape of the first gate electrode 31 and the pattern shape of the gate electrode 41, the first gate electrode 31 and the gate electrode 41 can be manufactured in the same manufacturing process. Thereby, the manufacturing process of the semiconductor element 1 is simplified and the manufacturing cost is reduced.

Further, the sheet resistance of the gate electrode 41 in the gate pad region 91 may be set higher than the sheet resistance (Ω / square) of the first gate electrode 31 in the element region 90. Thereby, the internal gate resistance rg can be further increased. For example, when the material of the first gate electrode 31 and the gate electrode 41 is polysilicon, a difference can be provided in the sheet resistance by changing the impurity concentration thereof.

  Thus, the semiconductor element 1 has high reliability and can be realized at low cost.

  Subsequently, a specific example of the planar shape of the gate electrode 41 will be described.

(First example)
FIG. 4 is a plan view of a principal part of the semiconductor element according to the first specific example.

FIG. 5 is a cross-sectional view of a principal part of the semiconductor element according to the first specific example, and FIG.
Sectional drawing, (b) is a YY 'sectional view of FIG. 4, (c) is a ZZ' sectional view of FIG.

In the semiconductor element 1A according to the first specific example, the gate electrode 41 includes a second gate electrode 41B as a second control electrode and a second gate electrode 41A as a third control electrode. At least a part of the second gate electrode 41 </ b> B and the entire third gate electrode 41 </ b> A are provided under the gate pad electrode 43. When viewed from the direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the planar shape of the third gate electrode 41A is rectangular. The second gate electrode 41B has a line shape. That is, the second gate electrode 41B is thinner than the third gate electrode 41A. For example, in the direction in which the gate electrodes 31 are periodically arranged, the width of the second gate electrode 41B is
It is narrower than the width of the third gate electrode portion 41A. Thereby, the electrical resistance of the second gate electrode 41B is higher than the electrical resistance of the third gate electrode 41A.

In the semiconductor element 1A, the gate pad electrode 43 is connected to the connection portion 31a of the first gate electrode 31 through the contact layer 42A. The connection part 31a is connected to the first gate electrode 3
Part of 1. A second gate electrode 41B is connected to the first gate electrode 31.

Thus, in the semiconductor element 1A, in addition to the first gate electrode 31, the gate electrode 41
Is provided under the gate pad electrode 43. A second gate insulating film 40 is provided between the gate electrode 41 and the drain electrode 60. Accordingly, in the semiconductor element 1A, in addition to the gate-drain capacitance (Cgd), the gate-drain capacitance (Cgd ′)
) Occurs between the gate pad electrode 43 and the drain electrode 60.

The gate pad electrode 43 and the gate electrode 41 are not in contact with each other in the entire region facing each other, but are electrically connected through a contact layer 42A provided in a part of the gate pad region 91. The gate electrode 41 includes a thin second gate electrode portion 41B. As a result, a high internal gate resistance rg is generated in the gate electrode 41.

Therefore, the time constant between the gate and the drain of the semiconductor element 1A is larger than that of the semiconductor element 100. As a result, the switching noise of the semiconductor element 1 </ b> A is suppressed as compared with the semiconductor element 100.

Note that the position of the contact layer is not necessarily limited to the corner of the gate pad region 91. Specific examples are shown below.

(First modification of the first specific example)
FIG. 6 is a main part plan view of a semiconductor element according to a first modification of the first specific example.

7 is a cross-sectional view of a principal part of a semiconductor device according to a first modification of the first specific example, (a) is a cross-sectional view taken along the line XX ′ of FIG. 6, and (b) is a cross-sectional view of FIG. It is Y 'sectional drawing.

In the semiconductor element 1B according to the first modification of the first specific example, the gate electrode 41 includes a third gate electrode 41C and a second gate electrode 41D. When viewed from a direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the planar shape of the third gate electrode 41 ^</ b ^> C is rectangular. However, the third
A thin line-like second gate electrode 41D enters from the end of the gate electrode 41C toward the center. The third gate electrode 41C has a shape in which a part of the third gate electrode 41C is divided by the second gate electrode 41D.

In the semiconductor element 1B, a part of the gate electrode 41 is narrowed. For example, the width of the second gate electrode 41D is narrower than the width of the third gate electrode 41C in the direction in which the gate electrodes 31 are periodically arranged. The width of the third gate electrode 41C is the divided third gate electrode 41.
The width may be C or the width of the third gate electrode 41C that is not divided. Thereby, the electrical resistance of the second gate electrode 41D is higher than the electrical resistance of the third gate electrode 41C.

In the semiconductor element 1B, the gate pad electrode 43 is connected to the connection portion 31b of the first gate electrode 31 through the contact layer 42B. The contact layer 42B is located near the center of the two corners of the gate pad region 91. The connection part 31b is connected to the first gate electrode 31.
Is part of. The gate pad electrode 43 is connected to the second gate electrode 41D through the contact layer 42B. The second gate electrode 41D is connected to the third gate electrode 41C.

In the semiconductor element 1 </ b> B, in addition to the first gate electrode 31, a gate electrode 41 is provided under the gate pad electrode 43. A second gate insulating film 40 is provided between the gate electrode 41 and the drain electrode 60. N-type drift layer 1 of gate pad region 91
The p-type base layer 12 is not provided on the surface of the n-type drift layer 1 in the element region 90.
A p-type base layer 12 is selectively provided on one surface.

Therefore, in the semiconductor element 1B, in addition to the gate-drain capacitance (Cgd), the gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60.

The gate pad electrode 43 and the gate electrode 41 are not in contact with each other in the entire region facing each other, but are electrically connected through a contact layer 42 </ b> B provided in a part of the gate pad region 91. The gate electrode 41 includes a thin second gate electrode 41D. As a result, a high internal gate resistance rg is generated in the gate electrode 41.

Therefore, the time constant between the gate and the drain of the semiconductor element 1B is larger than that of the semiconductor element 100. As a result, the switching noise of the semiconductor element 1B is suppressed as compared with the semiconductor element 100.

(Second modification of the first specific example)
FIG. 8 is a plan view of a principal part of a semiconductor element according to a second modification of the first specific example.

9 is a cross-sectional view of a principal part of a semiconductor device according to a second modification of the first specific example, (a) is a cross-sectional view taken along line XX ′ of FIG. 8, and (b) is a cross-sectional view of FIG. It is Y 'sectional drawing.

In the semiconductor element 1C according to the second modification of the first specific example, the gate electrode 41 includes a third gate electrode 41E, a second gate electrode 41F, a third gate electrode 41G, a second gate electrode 41H, including. When viewed from a direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the planar shape of the third gate electrodes 41E and 41G is rectangular.

However, a thin line-shaped second gate electrode 41F enters from the end of the third gate electrode 41E toward the center. The third gate electrode 41E has a shape in which a part of the third gate electrode 41E is divided by the second gate electrode 41F. Furthermore, a thin line-shaped second gate electrode 41H enters from the end of the third gate electrode 41G toward the center. In the third gate electrode 41G, a part of the third gate electrode 41G is divided by the second gate electrode 41H.

In the semiconductor element 1C, a part of the gate electrode 41 is narrowed. For example, in the direction in which the gate electrodes 31 are periodically arranged, the widths of the second gate electrodes 41F and 41H are narrower than the widths of the third gate electrodes 41E and 41G. The widths of the third gate electrodes 41E and 41G are the widths of the divided third gate electrodes 41E and 41G. Thereby, the second gate electrode 41F,
The electric resistance of 41H is higher than the electric resistances of the third gate electrodes 41E and 41G.

In the semiconductor element 1C, the gate pad electrode 43 is connected to the second gate electrode 41F and the second gate electrode 41H through the contact layer 42C. Contact layer 42C
Is located near the center of the gate pad region 91. The second gate electrode 41F is connected to the third gate electrode 41E. The second gate electrode 41H is connected to the third gate electrode 41G. The third gate electrode 41E is a connection portion 31b that is a part of the first gate electrode 31.
It is connected to the. Even in such a structure, the same effects as those of the semiconductor element 1B are obtained.

(Third modification of the first specific example)
FIG. 10 is a fragmentary plan view of a semiconductor element according to a third modification of the first specific example.

FIG. 11: is principal part sectional drawing of the semiconductor element which concerns on the 3rd modification of a 1st specific example, (a) is
XX 'sectional view of FIG. 10, (b) is a YY' sectional view of FIG.

In the semiconductor element 1D according to the third modification of the first specific example, the gate electrode 41 includes a third gate electrode 41I and a second gate electrode 41J. When viewed from the direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the planar shape of the third gate electrode 41I is rectangular. However, the third
A thin line-shaped second gate electrode 41J enters from the end of the gate electrode 41I toward the center. The third gate electrode 41I has a shape in which a part of the third gate electrode 41I is divided by the second gate electrode 41J.

In the semiconductor element 1D, a part of the gate electrode 41 is narrowed. For example, the width of the second gate electrode 41J is narrower than the width of the third gate electrode 41I in the direction in which the gate electrodes 31 are periodically arranged. The width of the third gate electrode 41I refers to the divided third gate electrode 41.
It may be the width of I or the width of the third gate electrode 41I that is not divided. Thereby, the electrical resistance of the second gate electrode 41J is higher than the electrical resistance of the third gate electrode 41I.

In the semiconductor element 1D, the gate pad electrode 43 is connected to the connection portion 31a that is a part of the first gate electrode 31 through the contact layer 42A. The gate pad electrode 43 is connected to the second gate electrode 41J through the contact layer 42B. The second gate electrode 41J is connected to the third gate electrode 41I.

As described above, in the semiconductor element 1D, the first location (contact layer 42A) that connects the gate pad electrode 43 serving as the lead electrode and the first gate electrode 31, the gate pad electrode 43 serving as the lead electrode, A second location (contact layer 42B) for connecting the gate electrode 41 is provided.

Even in such a structure, a gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60 in addition to the gate-drain capacitance (Cgd).

The gate pad electrode 43 and the gate electrode 41 are not in contact with each other in the entire region facing each other, but are electrically connected through a contact layer 42 </ b> B provided in a part of the gate pad region 91. The gate electrode 41 includes a thin second gate electrode 41J. As a result, a high internal gate resistance rg is generated in the gate electrode 41.

Therefore, the time constant between the gate and the drain of the semiconductor element 1D is larger than that of the semiconductor element 100. As a result, the switching noise of the semiconductor element 1D is suppressed compared to the semiconductor element 100.

(Fourth modification of the first specific example)
FIG. 12 is a fragmentary cross-sectional view of a semiconductor element according to a fourth modification of the first specific example.

In the semiconductor element 1E according to the fourth modification of the first specific example, the thickness of the second gate insulating film 40A under the gate electrode 41 is larger than the thickness of the first gate insulating film 30 under the first gate electrode 31. Is getting thicker.

According to such a structure, when a high voltage is applied between the drain and the source, avalanche breakdown under the gate pad electrode 43 hardly occurs. That is, in the semiconductor element 1E, a decrease in breakdown voltage and a decrease in avalanche resistance are suppressed.

(Second specific example)
FIG. 13 is a plan view of relevant parts of a semiconductor device according to a second specific example.

FIG. 14 is a cross-sectional view of a principal part of a semiconductor element according to a second specific example, and FIG.
X 'sectional drawing, (b) is YY' sectional drawing of FIG. 13, (c) is ZZ 'sectional drawing of FIG.

In the semiconductor element 1 </ b> F according to the second specific example, the gate electrode 41 is the third gate electrode 41.
K and the second gate electrode 41L. When viewed from the direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the gate electrode 41 has a comb shape. That is, the third gate electrode 41K and the second
The pattern formed by the gate electrode 41L has a comb shape. Line-shaped thin second
A plurality of line-shaped third gate electrodes 41K are connected to the gate electrode 41L. The second gate electrode 41L and the third gate electrode 41K are substantially orthogonal. Third gate electrode 41K
Are periodically arranged in the direction in which the second gate electrodes 41L extend.

In the semiconductor element 1F, a part of the gate electrode 41 is narrowed. For example, the width of the second gate electrode 41L in a direction substantially perpendicular to the direction in which the gate electrodes 31 are periodically arranged is narrower than the width of the third gate electrode 41K in the direction in which the gate electrodes 31 are periodically arranged. Thereby, the electrical resistance of the second gate electrode 41L becomes higher than the electrical resistance of the third gate electrode 41K.

In the semiconductor element 1F, the gate pad electrode 43 is connected to the connection portion 31b which is a part of the first gate electrode 31 through the contact layer 42B. Moreover, the connection part 31b is
It is connected to the second gate electrode 41L.

Even in such a structure, a gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60 in addition to the gate-drain capacitance (Cgd).

The gate pad electrode 43 and the gate electrode 41 are electrically connected through a contact layer 42B provided in a part of the gate pad region 91. The gate electrode 41 includes a thin second gate electrode 41L. Thereby, the gate electrode 41 has a high internal gate resistance r.
g is generated.

In the semiconductor element 1F, as viewed from a direction perpendicular to the main surface of the n ⁺ -type drain layer 10,
The gate electrode 41 is formed in a comb shape instead of a planar shape. Thus, by changing the pattern of the gate electrode 41 from the planar pattern to the line pattern, the magnitude of the gate-drain capacitance (Cgd ′) can be adjusted as appropriate.

Therefore, the time constant between the gate and the drain of the semiconductor element 1 </ b> F is larger than that of the semiconductor element 100. As a result, the switching noise of the semiconductor element 1 </ b> F is suppressed as compared with the semiconductor element 100.

In the semiconductor element 1F, a p-type guard ring layer 12b is selectively provided on the surface of the n-type drift layer 11 between the adjacent third gate electrodes 41K. The p-type guard ring layer 12 b is formed in the same manufacturing process as the p-type base layer 12. That is, the p-type guard ring layer 12 b is formed simultaneously with the p-type base layer 12.

By providing the p-type guard ring layer 12b, electric field concentration on the gate electrode 41 is suppressed, and a decrease in breakdown voltage under the gate pad electrode 43 is suppressed. Thereby, in the semiconductor element 1 </ b> F, a decrease in the avalanche resistance is suppressed.

(First modification of the second specific example)
FIG. 15 is a fragmentary cross-sectional view of a semiconductor element according to a first modification of the second specific example. FIG.
) Corresponds to the XX ′ section in FIG. 13, FIG. 15B corresponds to the YY ′ section in FIG. 13, and FIG. 15C corresponds to the ZZ ′ section in FIG. 13.

In the semiconductor element 1G according to the first modification of the second specific example, the adjacent p-type base layer 12 is used.
And a high-concentration n-type layer 11a as a fifth semiconductor layer is selectively provided on the surface of the n-type drift layer 11 between the adjacent p-type guard ring layers 12b. The impurity concentration of the high concentration n-type layer 11 a is higher than the impurity concentration of the n-type drift layer 11.

The on-resistance in the element region 90 is reduced by the arrangement of the high concentration n-type layer 11a. Furthermore, the charging effect on the high-concentration n-type layer 11a is enhanced, and the gate-drain capacitance (Cgd ′) under the gate pad electrode 43 can be further increased.

(Second modification of the second specific example)
FIG. 16 is a plan view of relevant parts of a semiconductor element according to a second modification of the second specific example.

In the semiconductor element 1H according to the second modification of the second specific example, the gate electrode 41 includes a third gate electrode 41M, a second gate electrode 41N, a second gate electrode 41P, a second gate electrode 41R, Second gate electrode 41Q. When viewed from a direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the gate electrode 41 has a lattice shape.

That is, a plurality of line-shaped third gate electrodes 41M are connected to the line-shaped thin second gate electrodes 41Q and 41R. The third gate electrode 41M and the second gate electrodes 41Q, 4
1R is substantially orthogonal. The third gate electrode 41M is periodically arranged in the direction in which the second gate electrodes 41Q and 41R extend. The second gate electrodes 41Q and 41R are arranged substantially in parallel.

In the semiconductor element 1H, a part of the gate electrode portion 41 is narrowed. For example, in the direction in which the gate electrodes 31 are periodically arranged, the widths of the second gate electrodes 41N and 41P are third.
It is narrower than the width of the gate electrode 41M. Thereby, the electrical resistances of the second gate electrodes 41N and 41P are higher than the electrical resistance of the third gate electrode 41M.

In the semiconductor element 1H, the gate pad electrode 43 is connected to the second gate electrode 41N and the second gate electrode 41P through the contact layer 42C. Second gate electrode 4
1N is connected to the second gate electrode 41Q. The second gate electrode 41P is connected to the second gate electrode 41R. The second gate electrode 41Q is connected to a connection portion 31b that is a part of the first gate electrode 31.

In the semiconductor element 1H, similarly to the semiconductor element 1F, a p-type guard ring layer 12b may be selectively provided on the surface of the n-type drift layer 11 between the adjacent third gate electrodes 41M.

Even in such a structure, a gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60 in addition to the gate-drain capacitance (Cgd). Further, a high internal gate resistance is generated in the gate electrode 41. Therefore, the semiconductor element 1H has the same effect as the semiconductor element 1F.

(Third Modification of Second Specific Example)
FIG. 17 is a plan view of relevant parts of a semiconductor device according to a third modification of the second specific example.

In the semiconductor element 1J according to the third modification of the second specific example shown in FIG. 17A, the gate electrode 41 includes a third gate electrode 41S. When viewed from a direction perpendicular to the main surface of the n ⁺ -type drain layer 10, the gate electrode 41 has a spiral shape.

That is, the thin line-shaped third gate electrode 41 </ b> S forms a spiral along the outer periphery of the rectangular gate pad electrode 43.

In the semiconductor element 1J, the gate pad electrode 43 is connected to the connection portion 31a which is a part of the first gate electrode 31 through the contact layer 42A. Further, the gate pad electrode 43 is connected to the third gate electrode 41S through the contact layer 42A.

Even in such a structure, a gate-drain capacitance (Cgd ′) is generated between the gate pad electrode 43 and the drain electrode 60 in addition to the gate-drain capacitance (Cgd). Further, by making the gate electrode 41 spiral, a high internal gate resistance is generated in the gate electrode 41. In the semiconductor element 1J, similarly to the semiconductor element 1F, the p-type guard ring layer 12 is formed on the surface of the n-type drift layer 11 between the adjacent third gate electrodes 41S.
b may be selectively provided. Therefore, the semiconductor element 1J has the same effect as the semiconductor element 1F.

As shown in FIG. 17B, the gate electrode 41 may include a third gate electrode 41Sa and a second gate electrode 41Sb. The line width of the second gate electrode 41Sb is narrower than the line width of the third gate electrode 41Sa. Thereby, the electrical resistance of the second gate electrode 41Sb becomes higher than the electrical resistance of the third gate electrode 41Sa. With such a structure, the internal gate resistance in the gate electrode 41 further increases.

In the embodiment, the semiconductor layer may have a super junction structure. A semiconductor device having a super junction structure will be described below with reference to schematic diagrams.

(Third example)
FIG. 18 is a cross-sectional view of main parts of a semiconductor device according to a third specific example.

In the semiconductor element 1 ^</ b ^> K according to the third specific example, the n-type drift layer 11 is provided on the n ⁺ -type drain layer 10 in the element region 90.

In the element region 90, the p-type base layer 12 is selectively provided on the surface of the n-type drift layer 11. An n ^{+ -type} source layer 13 is selectively provided on the surface of the p-type base layer 12. A p-type layer 12 a is provided on the surface of the n-type drift layer 11 at the outermost periphery of the element region 90. In the n-type drift layer 11, a p-type pillar layer 12 p as a sixth semiconductor layer connected to the p-type base layer 12 is periodically provided in a direction substantially parallel to the main surface of the n ⁺ -type drain layer 10. It has been.

That is, in the element region 90, a super junction structure including the p-type pillar layer 12p and the n-type pillar layer 11n is formed in the n-type drift layer 11. The n-type pillar layers 11 n and the p-type pillar layers 12 p are alternately arranged in a direction substantially parallel to the main surface of the n ⁺ -type drain layer 10. The upper end of the p-type pillar layer 12 p is connected to the p-type base layer 12.

In the gate pad region 91, an n-type drift layer having a lower concentration than the n-type pillar layer 11 n in the element region 90 is provided on the n ⁺ -type drain layer 10. This low-concentration n-type drift layer is hereinafter referred to as “n ⁻ -type layer 15”. The gate pad region 91 has p
The n-type drift layer in the gate pad region 91 is not provided,
That is, the impurity concentration of the n ⁻ -type layer 15 is lower than the impurity concentration of the n-type drift layer 11 in the element region 90. The impurity concentration of the n ⁻ -type layer 15 is desirably 1/10 or less of the n-type pillar layer 11 n (or the n-type drift layer 11). The n ⁻ -type layer 15 is in contact with the second gate insulating film 40. In the gate pad region 91, a super junction structure is not formed.

According to such a structure, the impurity concentration of the n-type pillar layer 11n can be set higher than the impurity concentration of the n-type drift layer 11. Thereby, the on-resistance of the semiconductor element 1K is further reduced.

However, in the MOSFET of the upper and lower electrode structure having the super junction structure, the drain-source capacitance (C) is obtained by the junction of the n-type pillar layer 11n and the p-type pillar layer 12p.
ds) becomes large. A large drain-source capacitance means a relatively small gate-drain capacitance. Therefore, it is considered that switching noise is generated from such a MOSFET. For example, there is a concern that the temporal change (dVds / dt) of the drain-source voltage cannot be controlled by the internal gate resistance (Vds: drain-source voltage).

However, in the semiconductor element 1K, the p-type base layer 12 and the super junction structure are not provided under the gate pad electrode 43. Thereby, the gate pad electrode 4
3, no drain-source capacitance (Cds) is generated. That is, the semiconductor element 1K
Also, the gate-drain capacitance is high. Thereby, in the semiconductor element 1K, the temporal change (dV) of the drain-source voltage (Vds) is caused by the internal gate resistance.
ds / dt) can be controlled well. As a result, switching noise is reduced.

Further, in the semiconductor element 1K, the low concentration n ⁻ -type layer 1 is formed under the gate pad electrode 43.
5 is provided. Therefore, when a high voltage is applied between the drain and source, the n ⁻ -type layer 1
5 is easily depleted, and avalanche breakdown under the gate pad electrode 43 is suppressed. Thereby, the semiconductor element 1K maintains a high breakdown voltage. Note that, even if a low-concentration p ⁻ -type layer is disposed in the n ⁻ -type layer 15 instead of the n ⁻ -type layer 15, the semiconductor element 1K maintains a high breakdown voltage.

(First Modification of Third Specific Example)
FIG. 19 is a fragmentary cross-sectional view of a semiconductor element according to a first modification of the third specific example.

In the semiconductor element 1L according to the first modification of the third specific example, a super junction structure is formed in the gate pad region 91 in addition to the element region 90. In the gate pad region 91, the n-type pillar layers 15 n and the p-type pillar layers 15 p are alternately arranged in a direction substantially parallel to the main surface of the n ⁺ -type drain layer 10.

The impurity concentration of n-type pillar layer 15n and p-type pillar layer 15p in gate pad region 91 is lower than the impurity concentration of n-type pillar layer 11n and p-type pillar layer 12p in element region 90. As a result, the drain-source capacitance in the gate pad region 91 does not increase. Further, in order to suppress the increase in drain-source capacitance, the p-type pillar layer 15p
Is preferably not connected to the p-type base layer 12.

Further, since the impurity concentration of the n-type pillar layer 15n and the p-type pillar layer 15p is low, the super junction structure in the gate pad region 91 is easily depleted. As described above, since the super junction structure in the gate pad region 91 is easily depleted, avalanche breakdown under the gate pad electrode 43 is difficult to occur. As a result, the breakdown voltage of the semiconductor element 1L is improved.

(Second modification of the third specific example)
FIG. 20 is a cross-sectional view of main parts of a semiconductor element according to a second modification of the third specific example.

In the semiconductor element 1M according to the second modification of the third specific example, a super junction structure is formed in the gate pad region 91 in addition to the element region 90. In the gate pad region 91, the n-type pillar layer 15n and the p-type pillar layer 15p are alternately arranged in a period in which the n-type pillar layer 11n and the p-type pillar layer 12p are alternately arranged in the element region 90. The cycle is shorter than the arrangement cycle.

Thereby, the super junction structure in the gate pad region 91 is more easily depleted. As a result, avalanche breakdown under the gate pad electrode 43 is difficult to occur.
As a result, the breakdown voltage of the semiconductor element 1M is improved. In order to further promote depletion of the super junction structure in the gate pad region 91, the impurity concentration of the n-type pillar layer 15n and the p-type pillar layer 15p in the gate pad region 91 is set to the n-type pillar layer 11n in the element region 90. Alternatively, it may be set lower than the impurity concentration of the p-type pillar layer 12p.

In the super junction structure, the p-type pillar layer may be the sixth semiconductor layer. Further, as a result of forming the p-type pillar layer in the n-type drift layer, an n-type pillar layer is formed between the p-type pillar layers. Therefore, the n-type pillar layer is referred to as an n-type drift layer or a second semiconductor layer. May be.

As described above, the embodiment is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the embodiment.

For example, in the embodiment, the first conductivity type is described as n-type and the second conductivity type is defined as p-type. However, the first conductivity type may be defined as p-type and the second conductivity type may be defined as n-type.

Although the planar gate structure has been described, the same effect can be obtained by using the same design under the gate pad even if the trench gate type gate structure is used.

In addition, although the plane pattern is not particularly described, the embodiment is not limited to the plane pattern of the MOS gate structure or the super junction structure, and any pattern such as a stripe shape, a mesh shape, a staggered shape, or a honeycomb shape may be used. Good.

The present invention is not limited to the opening position of the gate contact hole or the number of holes, and can be implemented at one place or a plurality of places of two or more places.

Further, a uniform p ^{+ -type} layer may be provided between the n ⁺ -type drain layer 10 and the n-type drift layer 11, and the semiconductor element may be an IGBT element. A part of the p ^{+ type} layer may be selectively opened to form a reverse conduction type IGBT element.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J, 1K, 1L, 1M, 1
00 semiconductor element, 10 n ^{+ type} drain layer, 11 n type drift layer, 11a high concentration n type layer, 11n n type pillar layer, 12 p type base layer, 12a p type layer, 1
2b p-type guard ring layer, 12p p-type pillar layer, 13 n ^{+ type} source layer, 15
the n ^- type layer, 15n n-type pillar layer, 15p p-type pillar layer, 30 a first gate insulating film, 31 a first gate electrode, 31a, 31b connecting portion, 40, 40A second gate insulating film, 41 gate electrode, 41B 41D, 41F, 41H, 41J, 41L,
41N, 41P, 41Q, 41R, 41S, 41Sb Second gate electrode, 41A, 41
C, 41E, 41G, 41I, 41K, 41M, 41Sa Third gate electrode, 42, 4
2A, 42B, 42C contact layer, 43 gate pad electrode, 60 drain electrode, 61, 62 contact layer, 63 source electrode, 90 element region, 91 gate pad region, 400 insulating film, Rg external gate resistance, rg internal gate resistance

Claims (10)

A first semiconductor layer of a first conductivity type;
A second semiconductor layer of a first conductivity type provided on the first semiconductor layer;
A third semiconductor layer of a second conductivity type selectively provided on the surface of the second semiconductor layer;
A fourth semiconductor layer of a first conductivity type selectively provided on a surface of the third semiconductor layer;
A first control electrode facing the first semiconductor layer, the third semiconductor layer, and the fourth semiconductor layer via a first insulating film;
An extraction electrode electrically connected to the first control electrode and provided on the second semiconductor layer in a second region different from the first region in which the first control electrode is provided;
A second control electrode and a third control electrode that are electrically connected to the lead electrode and are opposed to the second semiconductor layer via a second insulating film under the lead electrode;
A first main electrode connected to the first semiconductor layer;
A second main electrode connected to the third semiconductor layer and the fourth semiconductor layer;
With
The third semiconductor layer is not provided on the surface of the second semiconductor layer under the lead electrode,
At least a part of the second control electrode and at least a part of the third control electrode are provided under the extraction electrode,
The semiconductor element according to claim 1, wherein an electrical resistance of the second control electrode is higher than an electrical resistance of the third control electrode. The extraction electrode and the first control electrode are connected via a first contact layer,
2. The semiconductor element according to claim 1, wherein the lead electrode, the second control electrode, and the third control electrode are connected through a second contact layer. 3. The semiconductor device according to claim 1, wherein a sheet resistance of the second control electrode or the third control electrode is higher than a sheet resistance of the first control electrode. A fifth semiconductor layer of the first conductivity type having an impurity concentration higher than the impurity concentration of the second semiconductor layer is further provided on the surface of the second semiconductor layer between the adjacent third semiconductor layers. The semiconductor element according to any one of claims 1 to 3. The pattern formed from the second control electrode and the third control electrode as viewed from a direction perpendicular to the main surface of the first semiconductor layer has a comb shape. The semiconductor element as described in one. When viewed from a direction perpendicular to the main surface of the first semiconductor layer, the pattern of the third control electrode is:
The semiconductor element according to claim 1, wherein the semiconductor element has a spiral shape. A second conductivity type sixth semiconductor layer connected to the third semiconductor layer is further provided in the second semiconductor layer;
The semiconductor element according to claim 1, wherein the sixth semiconductor layer is periodically provided in a direction substantially parallel to the main surface of the first semiconductor layer. The sixth semiconductor layer is not provided in the second region,
The semiconductor element according to claim 7, wherein an impurity concentration of the second semiconductor layer in the second region is lower than an impurity concentration of the second semiconductor layer in the first region. 8. The impurity concentration of the second semiconductor layer and the sixth semiconductor layer in the second region is lower than the impurity concentration of the second semiconductor layer and the sixth semiconductor layer in the first region. The semiconductor element as described. The period in which the second semiconductor layer and the sixth semiconductor layer are alternately arranged in the second region is such that the second semiconductor layer and the sixth semiconductor layer are alternately arranged in the first region. The semiconductor element according to claim 7, wherein the semiconductor element has a period shorter than that of the semiconductor element.

Images