JP2017157661A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device in which a function of a semiconductor device is thoroughly changed without layout change of semiconductor elements.SOLUTION: A semiconductor device comprises in the following order: an insulation layer; a wiring layer having wiring buried in a surface of the insulation layer; and a Schottky barrier diode element. The Schottky barrier diode element is located on the wiring of the wiring layer; and the Schottky barrier diode element has a Schottky electrode, an ohmic electrode and an oxide semiconductor layer lying between the Schottky electrode and the ohmic electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device.

  A normal semiconductor device has a configuration in which a transistor or the like is formed on a substrate of a semiconductor element, and a plurality of wiring layers are formed on the transistor. In such a semiconductor device, the layout formed on the substrate of the semiconductor element is designed based on functions required for the semiconductor device.

  In recent years, as described in Non-Patent Documents 1 to 6, it has been studied to form a thin film transistor using a compound semiconductor layer.

Patent Document 1 proposes a semiconductor device in which a thin film transistor (TFT) is provided as an element having a new function in a wiring layer of a semiconductor device.
Patent Document 2 proposes a CMOS circuit in which an n-type oxide semiconductor layer and a p-type oxide semiconductor layer are provided in the same plane wiring layer as a new functional element.
Patent Document 3 proposes that an oxide semiconductor element having a structure in which a channel portion between a source and a drain and a gate electrode are separated from each other when viewed from above is formed in a wiring layer.
In these, an oxide semiconductor TFT having mainly a new function is formed in a wiring layer, and a CMOS circuit or the like is installed.

JP 2010-141230 A JP 2014-045209 A JP 2014-0775570 A

"Control of p- and n-type conductivity in putter of deposition of undoped ZnO", Gang Xiong et al., App. Phys. Lett. , Vol. 80, no. 7,18 February 2002 “High mobility bottom gate InGaZnO thin film transistors with SiOx etch stopper”, Minlyu Kim et al., App. Phys. Lett. , Vol. 90, 212114 (2007) “High mobility thin-film transducers with InGaZnO channel fabricated by room temperature rf-magnetron sputtering”, Hisato Yabuta et al., 8 names. Phys. Lett. , Vol. 89, 112123 (2006) "Highly Stable Ga2O3-In2O3-ZnO TFT for Active-Matrix Organic Light-Emitting 1D eItE e6, IdE eM eD, eI eD e e e n e i e e d e e e i e e e i e d e e e i e e i e e e d e e i e e e e e e e e e d e e e i e e e e d e e e i "Integrated circuits based on amorphous, indium-gallium-zinc-oxide-channel thin-film transistors", M.M. Ofuji and 8 others, ECS Transactions, 3 (8) 293-300 (2006) “Wide-bandgap high-mobility ZnO thin-film transducers produced at room temperature”, Elvira M. et al. C. Fortunato and 6 others, App. Phys. Lett. , Vol. 85, no. 13, 27 September 2004

Conventionally, only wiring, capacitive elements, fuses, and the like have been formed in the wiring layer on the semiconductor element, so there was a certain limit to changing the function of the semiconductor device only by changing the configuration of the wiring layer. . Accordingly, an object of the present invention is to provide a semiconductor device in which the function of the semiconductor device is significantly changed without changing the layout of the semiconductor element.
If the function of the semiconductor device can be changed without changing the layout of the semiconductor element on the substrate, the manufacturing cost of the semiconductor device can be reduced.

According to the present invention,
A semiconductor element;
A wiring layer having an insulating layer and a wiring embedded in a surface of the insulating layer;
Schottky barrier diode element
In this order,
The Schottky barrier diode element is located on the wiring of the wiring layer;
The Schottky barrier diode element can provide a semiconductor device having a Schottky electrode, an ohmic electrode, and an oxide semiconductor layer between the Schottky electrode and the ohmic electrode.

  In the semiconductor device of the present invention, a Schottky barrier diode element is provided in contact with the wiring of the wiring layer. As a result, the function of the semiconductor device can be changed without changing the layout of the semiconductor element.

  In the semiconductor device, preferably, a relationship between a work function (φs) of the Schottky electrode and a work function (φox) of the oxide semiconductor layer is φs> φox.

If the above relationship is established, it is preferable because the barrier height can be increased. A larger work function of the Schottky electrode is advantageous. For example, the work function is 4.3 eV or more, preferably 4.5 eV or more, and more preferably 4.7 eV or more. The work function of the oxide semiconductor is advantageously smaller, for example, less than 4.3, preferably less than 4.2 eV, more preferably less than 4.1 eV, and even more preferably 4. It is less than 1 eV.
The work function can be measured by photoelectron spectroscopy.

  In the semiconductor device, preferably, a height of a buyer height formed by the Schottky electrode and the oxide semiconductor is 0.2 eV or more.

If the height of the barrier height is high, the performance of the Schottky barrier diode element is enhanced. The height of the barrier height is more preferably 0.3 eV or more, further preferably 0.4 eV or more, and particularly preferably 0.5 eV or more.
The height of the barrier height includes a method of analyzing leakage current by reverse IV measurement of a Schottky barrier diode element and a method of analyzing forward IV measurement by the Chang method, etc. It can be measured by analyzing the leakage current by IV measurement.

  In the semiconductor device, preferably, the ohmic electrode includes, in order from the oxide semiconductor layer side, an electrode having conductivity even when oxidized, an antioxidant electrode, and a resistance-reducing electrode, Even if oxidized, it can also serve as a conductive electrode or the resistance-reducing electrode.

  The ohmic electrode has a function for making ohmic contact between the wiring and the oxide semiconductor layer. Preferably, the electrode has conductivity even when oxidized between the wiring and the oxide semiconductor layer, an oxidation preventing electrode, and a resistance reduction. Consists of electrodes.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device which changed the function of the semiconductor device significantly can be provided, without changing the layout of a semiconductor element.

1 is a cross-sectional view showing a configuration of a semiconductor device according to a first embodiment of the present invention. It is sectional drawing which shows the structure of a part of semiconductor device which concerns on the 2nd Embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
Since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description, it is not restricted to these aspects.

FIG. 1 is a cross-sectional view showing a configuration of a semiconductor device according to the first embodiment of the present invention.
As shown in FIG. 1, the semiconductor device 1 includes a semiconductor element 100, a first wiring layer 200, and a Schottky barrier diode element 300 in this order.

  In the semiconductor element 100, a MOS transistor is formed on the semiconductor substrate 110. The semiconductor element 100 functions as a transistor or a capacitor element, and includes a gate insulating layer 112, a gate electrode 114, and impurity regions 116 that are a source and a drain. The element region where the semiconductor element 100 is formed is isolated by an element isolation film 102. The semiconductor element 100 overlaps at least partly with the oxide semiconductor layer 320 in plan view (see the plan view line 10).

  The first wiring layer 200 includes an insulating layer 220 formed above the semiconductor element 100 and first wirings 212 and 214 embedded in the surface of the insulating layer 220. The film thickness of the first wiring layer 200 is usually 0.5 μm to 5 μm.

  The first wirings 212 and 214 are, for example, copper wirings and are embedded in the insulating layer 220 using a damascene method. The width of the first wiring 212 is, for example, not less than 50 nm and not more than 5000 nm.

  As the insulating layer 220, for example, a low dielectric constant insulating layer having a dielectric constant lower than that of silicon oxide and a relative dielectric constant of 2.7 or less is suitably used. As the low dielectric constant insulating layer, for example, SiLK (registered trademark), SiOC (H) film, hydrogen silsesquioxane (HSQ) film, methylated hydrogen silsesquioxane (MHSQ) film, methyl silsesquioxane ( MSQ) membranes and porous membranes thereof.

The Schottky barrier diode element 300 is located on the first wiring 212 and is connected to the first wiring 212.
The Schottky barrier diode element 300 includes a Schottky electrode 310 or 330, an ohmic electrode 310 or 330, and an oxide semiconductor layer 320 between the opposing electrodes 310 and 330. The electrode 310 may be a Schottky electrode and the electrode 330 may be an ohmic electrode, and the electrode 330 may be a Schottky electrode and the electrode 310 may be an ohmic electrode.

The oxide semiconductor layer 320 includes an amorphous oxide semiconductor such as Ga ₂ O ₃ (GO), InGaZnOx (IGZO), InSnZnOx (ITZO), InGaMgOx (IGMO), InAlZnOx (IAZO), InAlMgOx (IAGO), InGaOx, and the like. It can be composed of a crystalline oxide semiconductor such as (IGO), InAlOx (IAO), InMgOx (IMO), InAlYOx (IAYO). The oxide semiconductor layer 320 may be formed by introducing oxygen vacancies or introducing impurities. The oxide semiconductor layer 320 may have a single-layer structure of these oxides or a stacked structure of two layers or multiple layers.
The oxide semiconductor layer 320 typically has a thickness of 500 nm to 10,000 nm.

The Schottky electrode may be composed of one or more metals (including alloys) selected from Au, Pt, Pd, Ni, Ru, Mo, and Ti, or a laminate of the metal and its metal oxide. it can. Preferred metals are those with higher work functions. In the case of an expensive metal, it may be used very thinly on the surface in contact with the oxide semiconductor layer, and another metal may be stacked. Ni, Ru, Mo, Ti and the like are preferably used.
The thickness of the Schottky electrode is usually 2 nm to 500 nm.

The material of the ohmic electrode is not particularly limited as long as the ohmic electrode can be satisfactorily connected to the oxide semiconductor layer, but preferably one or more metals selected from Ti, Mo, Ag, In, Al, W, Co, and Ni, or The compound (oxide etc.), more preferably one or more metals selected from Mo, Ti, Au, Ag and Al, or a compound thereof. The ohmic electrode can be composed of a plurality of layers.
The thickness of the ohmic electrode is usually 10 nm to 5 μm.

  An insulating layer 700 is formed on the Schottky barrier diode element 300. As the insulating layer 700, the above-described low dielectric constant insulating layer can be preferably used. A wiring 800 is embedded in the insulating layer 700. It is electrically drawn by a wiring 800 formed on the Schottky barrier diode element 300.

A contact layer 400 and a second wiring layer 500 are formed between the first wiring layer 200 and the semiconductor substrate 110 from the semiconductor substrate 110 side. The second wiring layer 500 is located on the contact layer 400. The second wiring layer 500 is provided for wiring of the semiconductor element 100, and the contact layer 400 is provided for electrodes for electrically contacting the semiconductor element 100 for extracting signals from the semiconductor element 100 and the second wiring 510.
The contact layer 400 includes an insulating layer 420 and a contact electrode 410. The second wiring layer 500 includes an insulating layer 520 and a second wiring 510.
The second wiring 510 is connected to the semiconductor element 100 through the contact electrode 410. The second wiring 510 is connected to the first wiring 214 through a via 230 embedded in the insulating layer 220.

  The insulating layers 420 and 520 can be formed of the low dielectric constant layer described above. The insulating layer can also be formed of a silicon oxide layer. Further, a diffusion prevention film 600 such as a SiCN film is formed between the second wiring layer 500 and the first wiring layer 200. The diffusion prevention film 600 prevents the metal ions of the oxide semiconductor from diffusing into the semiconductor element 100 when the first wiring layer 200 and the Schottky barrier diode element 300 are formed, and causing the performance of the semiconductor element 100 to deteriorate. Provided for. The oxide semiconductor layer 320 is electrically connected to the semiconductor element 100 through the via 230.

  In the present embodiment, a semiconductor substrate 110, a gate insulating film 112, and a gate electrode 114 are provided in the semiconductor element 100. This element functions as, for example, a transistor (switching element) or a storage element. Therefore, the Schottky barrier diode element 300 having a new Schottky function can be provided in contact with the first wiring 212 of the wiring layer 200. As a result, without changing the layout (configuration) of the semiconductor element 100, The function of the semiconductor device 1 can be significantly changed.

  FIG. 2 is a cross-sectional view showing a partial configuration of a semiconductor device according to the second embodiment of the present invention. The semiconductor device 2 of this embodiment is different from the semiconductor device 1 of the first embodiment in that the Schottky electrode 310, the oxide semiconductor layer 320, and the ohmic electrode 330 have a multilayer configuration.

  When the Schottky electrode 310 is formed on the first wiring layer 200, as illustrated in FIG. 2, the Schottky electrode 310 includes a resistance reduction electrode 312 that reduces contact resistance with the first wiring 212, and a resistance reduction electrode 312. It is possible to form a laminate of an anti-oxidation electrode 314 that suppresses oxidation of the barrier electrode 316 and a barrier electrode 316 that forms a Schottky barrier.

  The antioxidant electrode 314 can also serve as the resistance reducing electrode 312 and can also serve as the barrier electrode 316. Therefore, the anti-oxidation electrode 314 (cum-resistance reducing electrode 312) and the barrier electrode 316 may be laminated, or the resistance-reducing electrode 312 and the anti-oxidation electrode 314 (barrier electrode 316) may be laminated (two-layer laminate).

For the resistance reduction electrode 312, a metal having a small contact resistance with copper wiring or the like can be used, and Ti, Mo, Au, Ag, Al, or the like can be used. Preferably, Ti, Mo, Ag, and Al.
For the oxidation preventing electrode 314, one or more metals (including alloys) selected from Mo, Ti, Zn, In, Sn, InSn alloy, Pt, Pd, and Ru can be used.
As the barrier electrode 316, one or more metals selected from Au, Pt, Pd, Ni, Ru, Mo, and Ti, or metal oxides thereof can be used. A laminate of a metal layer and a metal oxide layer can be suitably used.

  The thickness of each of the resistance reducing electrode 312, the antioxidant electrode 314, and the barrier electrode 316 is usually 1 nm to 50 nm. If the thickness is less than 1 nm, the function may not be exhibited. If the thickness exceeds 50 nm, the resistance value of the electrode itself may be too large. Preferably it is 3-30 nm, More preferably, it is 5-20 nm.

  In this embodiment, the oxide semiconductor layer 320 is a stacked body in which an oxide semiconductor layer 322 having a high barrier height and an oxide semiconductor layer 324 having a high withstand voltage are stacked from the Schottky electrode 310 side.

  The oxide semiconductor layer having a high barrier height is preferably made of an oxide having a large band gap and a small work function. Suitable oxides include oxides containing light elements such as gallium oxide, magnesium oxide, and aluminum oxide. Specifically, materials having a high band gap such as indium gallium zinc oxide (IGZO), indium gallium magnesium oxide (IGMO), indium aluminum zinc oxide (IAZO), indium aluminum magnesium oxide (IAMO), and the like can be given. . The higher the band gap, the higher the voltage resistance, which is preferable. For example, it is 3.2 eV or more, preferably 3.4 eV or more, more preferably 3.5 eV or more.

The carrier density of the oxide semiconductor layer 322 having a high barrier height is preferably 1 × 10 ¹⁶ cm ⁻³ or less, 1 × 10 ¹⁵ cm ⁻³ or less, and 1 × 10 ¹⁴ cm ⁻³ or less. If it is 1 × 10 ¹³ cm ⁻³ or less, the behavior as an insulator may appear. An oxide having a carrier density exceeding 1 × 10 ¹⁹ cm ⁻³ may have a reduced voltage resistance.

In addition, the oxide semiconductor layer 324 with high withstand voltage is preferably formed using an oxide having a low state density of impurity levels at a deep level in the band gap. As such an oxide, an oxide with high crystallinity or an oxide with few oxygen vacancies and a low deep state density is preferable. For example, indium gallium oxide (IGO), indium aluminum oxide (IAO), indium magnesium oxide (IMO), indium aluminum yttrium oxide (IAYO), or the like can be preferably used. The carrier density of the oxide having high withstand voltage is preferably 1 × 10 ¹⁸ cm ⁻³ or less, 1 × 10 ¹⁷ cm ⁻³ or less, and 1 × 10 ¹⁵ cm ⁻³ or less. If it is 1 × 10 ¹⁴ cm ⁻³ or less, it may behave as an insulator and it may be difficult to make ohmic contact.

  The thickness of the oxide semiconductor layer 320 is usually 500 nm or more and 10,000 nm or less. The ratio between the thickness and thickness of the oxide semiconductor layer 322 having a high barrier height and the oxide semiconductor layer 324 having a high withstand voltage is selected from the desired withstand voltage and the forward resistance value as long as it is within the above range. it can. The thickness of the oxide semiconductor layer 322 having a high barrier height is smaller than that of the oxide semiconductor layer 324 having a high positive withstand voltage, and the resistance value in the forward direction is low with a high withstand voltage.

  As shown in FIG. 2, the ohmic electrode 330 can have a stacked structure of an electrode 332 that has conductivity even when oxidized, an oxidation preventing electrode 334 that prevents oxidation due to oxygen diffusion, and a resistance reduction electrode 336.

  The oxidation preventing electrode 334 can also serve as the conductive electrode 332 or the resistance reduction electrode 336 even when oxidized. Therefore, the anti-oxidation electrode 334 (also used as the electrode 332 having conductivity even when oxidized) and the resistance-reducing electrode 336 may be stacked to form a two-layer structure, or the electrode 332 having conductivity even when oxidized and the anti-oxidation. The electrode 334 (also used as the resistance reduction electrode 336) may be stacked to have a two-layer structure.

The electrode 332 having conductivity even when oxidized includes Zn, In, Sn, InSn alloy, Mo, Ti, ZnO, In ₂ O ₃ , SnO ₂ , MoO ₂ , TiO ₂ , indium tin oxide (ITO), Indium zinc oxide or the like can be used. Among them, In, Sn, InSn alloy, ITO, and indium zinc oxide are preferable.

  As the antioxidant electrode 334 of the Schottky electrode 310, Mo, Ti, Zn, In, Sn, InSn alloy, Pt, Pd, Ru, or the like can be used as the antioxidant electrode 334.

  Ti, Mo, Au, Ag, Al, or the like can be used for the contact reduction electrode 336, as in the resistance reduction layer 312 of the Schottky electrode 310. Preferably, Ti, Mo, Ag, and Al.

The oxidized electrode 332, the oxidation-preventing electrode 334, and the contact reducing electrode 336 may be made of the same metal even when oxidized, but not a complete oxide layer in order to function as a contact reducing electrode. It preferably has a function as a semioxide layer or metal layer having a function of inhibiting oxidation.
Preferably, a metal indium layer can be used for these electrodes 332, 334, 336. Mo metal, Ti metal, or the like as a wiring material may be used for the contact reduction electrode 336.

  The film thicknesses of the electrode 332, the anti-oxidation electrode 334, and the resistance reduction electrode 336 that have conductivity even when oxidized are usually 1 nm to 50 nm, respectively. If the thickness is less than 1 nm, the function may not be exhibited. If the thickness exceeds 50 nm, the resistance value of the electrode itself may be too large. Preferably they are 3 nm-30 nm, More preferably, they are 5 nm-20 nm.

  As a method for forming the layer or electrode, a sputtering method, an ion plating method, an EB vapor deposition method, or the like can be used. A sputtering method using a sputtering target is preferred. When an oxide film is desired to be formed, an oxide-based sputtering target may be used, or a metal target may be used for reactive sputtering with oxygen.

  The first wiring 212 is copper, the resistance reduction electrode 312 is Mo (thickness: 10 nm), the oxidation preventing electrode 314 is Pt (thickness: 10 nm), the barrier electrode 316 is PtO (thickness: 10 nm), and the barrier height is high. Gallium oxide (thickness: 25 nm) for the oxide semiconductor layer 322, indium gallium oxide (thickness: 175 nm) for the oxide semiconductor layer 324 having high withstand voltage, and In (thickness) for the electrode 332 that has conductivity even when oxidized. When the Schottky barrier diode 300 is configured with Mo (thickness: 20 nm) for the anti-oxidation electrode 334 and the resistance reduction electrode 336 and Al (thickness: 1 μm) for the wiring 800, a breakdown voltage of 63 V (withstand voltage) When a forward current of 1 V was applied at a voltage of 3.15 MV / cm), a current of 50 A was observed.

  Although the embodiments and examples of the present invention have been described above, those skilled in the art can easily make many changes to the illustrated embodiments and examples without substantially departing from the features of the present invention. is there. These modifications are included in the scope of the present invention.

1, 2 Semiconductor device 10 Plane view line

DESCRIPTION OF SYMBOLS 100 Semiconductor element 102 Element isolation film 110 Semiconductor substrate 112 Gate insulating layer 114 Gate electrode 116 Impurity region

200 First wiring layer 212, 214 First wiring 220 Insulating layer 230 Via

DESCRIPTION OF SYMBOLS 300 Schottky barrier diode element 310 Schottky electrode or ohmic electrode 312 Resistance reduction electrode 314 Antioxidation electrode 316 Barrier electrode 320 Oxide semiconductor layer 322 Oxide semiconductor layer 324 with high barrier height 330 Oxide semiconductor layer with high voltage resistance 330 Ohmic Electrode or Schottky electrode 332 Electrode having conductivity even when oxidized 334 Antioxidation electrode 336 Resistance reduction electrode

400 Contact layer 410 Contact electrode 420 Insulating layer

500 Second wiring layer 510 Second wiring 520 Insulating layer

600 Diffusion prevention layer 700 Insulating layer 800 Wiring

Claims (4)

A semiconductor element;
A wiring layer having an insulating layer and a wiring embedded in a surface of the insulating layer;
Schottky barrier diode element
In this order,
The Schottky barrier diode element is located on the wiring of the wiring layer;
The Schottky barrier diode element has a Schottky electrode, an ohmic electrode, and an oxide semiconductor layer between the Schottky electrode and the ohmic electrode.   The semiconductor device according to claim 1, wherein a relationship between a work function (φs) of the Schottky electrode and a work function (φox) of the oxide semiconductor layer is φs> φox.   3. The semiconductor device according to claim 1, wherein a height of a barrier height formed by the Schottky electrode and the oxide semiconductor layer is 0.2 eV or more. The ohmic electrode is sequentially from the oxide semiconductor layer side,
An electrode that is conductive even when oxidized,
Including an antioxidant electrode, and a resistance-reducing electrode,
4. The semiconductor device according to claim 1, wherein the oxidation preventing electrode can also serve as a conductive electrode or the resistance reduction electrode even if the oxidation is performed. 5.

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