Abstract: Provided is a semiconductor super junction power device. The semiconductor super junction power device includes an MOSFET cell array composed of multiple super junction MOSFET cells. Each of multiple MOSFET cells includes a p-type body region located at the top of an n-type drift region, a p-type columnar doping region located below the p-type body region, an n-type source region located in the p-type body region, a gate dielectric layer located above the p-type body region, a gate electrode located above the p-type body region, an n-type floating gate located above the p-type body region and an opening located in the gate dielectric layer, where in a lateral direction, the gate electrode is located on one side close to the n-type source region; an opening located in the gate dielectric layer, where the n-type floating gate contacts the p-type body region through the opening to form a p-n junction diode.

Abstract: A method for manufacturing a semiconductor device includes forming a first vertical transistor on a semiconductor substrate, and forming a second vertical transistor stacked on the first vertical transistor. In the method, an isolation layer is formed between the first and second vertical transistors. The isolation layer includes a rare earth oxide.

Abstract: The present disclosure relates to a method of forming an integrated chip. The method includes forming a plurality of isolation structures within a substrate. The substrate is selectively etched to form a gate base recess within the substrate. The plurality of isolation structures are selectively etched to form a plurality of gate extension trenches extending outward from the gate base recess; forming a conductive material within the gate base recess and the plurality of gate extension trenches to form a gate electrode; and forming a source region and a drain region on opposing sides of the gate electrode.

Abstract: A device comprises source/drain regions over a substrate and spaced apart along a first direction, a first gate structure between the source/drain regions, and a first channel structure surrounded by the first gate structure. The first channel structure comprises alternately stacking first semiconductor layers and second semiconductor layers. When viewed in a cross section taken along a second direction perpendicular to the first direction, central axes of the second semiconductor layers are laterally offset from central axes of the first semiconductor layers.

Abstract: A semiconductor device includes source and drain regions, a channel region between the source and drain regions, and a gate structure over the channel region. The gate structure includes a gate dielectric over the channel region, a work function metal layer over the gate dielectric and comprising iodine, and a fill metal over the work function metal layer.

Abstract: A method of making a deformable electronic device comprises forming a multilayer device structure comprising functional layers on a flexible substrate. At least one, some or all of the functional layers comprises a stack of 2D monolayers, and a number or proportion of misaligned interfaces within each stack of 2D monolayers is controlled to obtain a predetermined bending stiffness. Each of the misaligned interfaces comprises a twist angle and/or lattice mismatch between adjacent 2D monolayers. The functional layers may include electronically active layers and other layers having a dielectric, insulating, and/or protective function.

Abstract: An electrostatic discharge protection device includes: an emitter region disposed on a semiconductor substrate; a base region surrounding the emitter region; a first collector region surrounding the base region; a second collector region surrounding the first collector region; a second conductivity-type drift region below the emitter region, and being deeper than the base region; a second conductivity-type well region disposed below the base region, and having a junction interface with the second conductivity-type drift region; and a plurality of isolation portions disposed between the emitter region, the base region, and the first collector region and the second collector region.

Abstract: The present disclosure provides a method that includes receiving a semiconductor substrate that includes an integrated circuit (IC) cell and a well tap cell surrounding the IC cell; forming first fin active regions in the well tap cell and second fin active regions in the IC cell; forming a hard mask within the well tap cell, wherein the hard mask includes openings that define first source/drain (S/D) regions on the first fin active region of the well tap cell; forming gate stacks on the second fin active regions within the IC cell and absent from the well tap cell, wherein the gate stacks define second S/D regions on the second fin active regions; epitaxially growing first S/D features in the first S/D regions using the hard mask to constrain the epitaxially growing; and forming contacts landing on the first S/D features within the well tap cell.

Abstract: Among multiple drain regions, a contact surface area between second contacts and a drain region most proximal to a central portion of an element region in a second direction is less than a contact surface area between second contacts and a drain region disposed on an outermost side of the element region in the second direction. The multiple drain regions are arranged in the second direction.

Abstract: Embodiments of the disclosure provide a lateral bipolar transistor with a base layer of varying horizontal thickness, and related methods to form the same. A lateral bipolar transistor may include an emitter/collector (E/C) layer on a semiconductor layer. A first base layer is on the semiconductor layer and horizontally adjacent the E/C layer. The first base layer has a lower portion having a first horizontal width from the E/C layer. The first base layer also has an upper portion on the lower portion, with a second horizontal width from the E/C layer greater than the first horizontal width. A second base layer is on the first base layer and adjacent a spacer. The upper portion of the first base layer separates a lower surface of the second base layer from the E/C layer.

Abstract: A semiconductor metal-oxide-semiconductor field effect transistor (MOSFET) transistor with increased on-state current obtained through intrinsic bipolar junction transistor (BJT) of MOSFET has been described. Methods of operating the MOS transistor are provided.

Abstract: The present disclosure relates to an integrated chip. The integrated chip includes a substrate having a first semiconductor material. A second semiconductor material is disposed on the first semiconductor material. The second semiconductor material is a group IV semiconductor or a group III-V compound semiconductor. A passivation layer is disposed on the second semiconductor material. The passivation layer includes the first semiconductor material. A first doped region and a second doped region extend through the passivation layer and into the second semiconductor material.

Abstract: A varactor may include a gate electrode; a graphene layer; and a ferroelectric layer between the gate electrode and the graphene layer.

Abstract: Provided is a group III nitride laminate for improving device characteristics, including: an underlying substrate; a first layer that is formed on the underlying substrate and is made of aluminum nitride; and a second layer that is formed on the first layer and is made of gallium nitride, wherein the first layer has a thickness of more than 100 nm and 1 ?m or less, a full width at half maximum of (0002) diffraction determined through X-ray rocking curve analysis is 250 seconds or less, and a full width at half maximum of (10-12) diffraction determined through X-ray rocking curve analysis is 500 seconds or less.

Abstract: A method of fabricating a semiconductor structure includes selective use of a cladding layer during the fabrication process to provide critical dimension uniformity. The cladding layer can be formed before forming a recess in an active channel structure or can be formed after filling a recess in an active channel structure with dielectric material. These techniques can be used in semiconductor structures such as gate-all-around (GAA) transistor structures implemented in an integrated circuit.

Abstract: A semiconductor device includes: a semiconductor substrate having opposing first and second main surfaces; a plurality of transistor cells each including a source region, a drift zone, a body region separating the source region from the drift zone, a field plate trench extending into the drift zone and including a field plate, and a planar gate on the first main surface and configured to control current through a channel of the body region; a drain region at the second main surface; and a diffusion barrier structure including alternating layers of Si and oxygen-doped Si and a Si capping layer on the alternating layers of Si and oxygen-doped Si. The diffusion barrier structure may be interposed between body regions of adjacent transistor cells and/or extend along the channel of each transistor cell and/or vertically extend in the semiconductor substrate between adjacent field plate trenches.

Abstract: Various embodiments of the present disclosure are directed towards a method for forming a semiconductor structure, the method includes forming a buffer layer over a substrate. An active layer is formed on the buffer layer. A top electrode is formed on the active layer. An etch process is performed on the buffer layer and the substrate to define a plurality of pillar structures. The plurality of pillar structures include a first pillar structure laterally offset from a second pillar structure. At least portions of the first and second pillar structures are spaced laterally between sidewalls of the top electrode.

Abstract: A semiconductor structure and a fabrication method of the semiconductor structure are provided. The method includes providing a substrate, forming a first dielectric layer and a plurality of gate structures, forming source-drain doped regions, and forming a source-drain plug. The first dielectric layer covers surfaces of the gate structure, the source-drain doped region and the source-drain plug. The method also includes forming a first plug in the first dielectric layer, and forming a second dielectric layer on the first dielectric layer. The first plug is in contact with a top surface of one of the source-drain plug and the gate structure. The second dielectric layer covers the first plug. Further, the method includes forming a second plug material film in the first and second dielectric layers. The second plug material film is in contact with the top surface of one of the source-drain plug and the gate structure.

Abstract: An embodiment of the invention may include a Vertical Field Effect Transistor (VFET) structure, and method of making that structure, having a first VFET and a second VFET. The first VFET may include a single liner between a first source/drain epi and a contact. The second VFET may include two liners between a second source/drain epi and a contact. This may enable proper contact liner matching for differing VFET devices.

Abstract: A semiconductor device includes a substrate. The device includes a stacked film that includes a plurality of first electrode layers provided over the substrate and separated from each other in a first direction perpendicular to a front surface of the substrate and a plurality of second electrode layers provided over the first electrode layer and separated from each other in the first direction. The device further includes a first insulating film and a second insulating film that penetrate the plurality of first electrode layers and the plurality of second electrode layers in the first direction. The stacked film further includes a first gap portion including a first portion provided between the substrate and a lowermost layer of the plurality of first electrode layers and a second portion connected to the first portion, penetrating the plurality of first electrode layers in the first direction, between the first insulating film and the second insulating film.

Abstract: A semiconductor may include an active region, an epitaxial source/drain formed in and extending above the active region, and a first dielectric layer formed over a portion of the active region. The semiconductor may include a first metal gate and a second metal gate formed in the first dielectric layer, a second dielectric layer formed over the first dielectric layer and the second metal gate, and a titanium layer, without an intervening fluorine residual layer, formed on the metal gate and the epitaxial source/drain. The semiconductor may include a first metal layer formed on top of the titanium on the first metal gate, a second metal layer formed on top of the titanium layer on the epitaxial source/drain, and a third dielectric layer formed on the second dielectric layer. The semiconductor may include first and second vias formed in the third dielectric layer.

Abstract: Methods and devices that provide a first fin structure, a second fin structure, and a third fin structure disposed over a substrate. A dielectric fin is formed between the first fin structure and the second fin structure, and a conductive line is formed between the second fin structure and the third fin structure.

Abstract: A device is disclosed. The device includes a source contact in a source contact trench and a drain contact in a drain contact trench, a channel under the source contact and the drain contact, a first spacing layer on a bottom of the source contact trench and a second spacing layer on a bottom of the drain contact trench. The first spacing layer and the second spacing layer are on the surface of the channel. The device also includes a gate electrode below the channel and a dielectric above the gate electrode and underneath the channel.

Abstract: A semiconductor device includes: a first electrode; a first semiconductor layer; a first insulating film extending downward from an upper surface of the first semiconductor layer, the first insulating film being columnar; a second electrode located in the first insulating film, the second electrode extending in a vertical direction, the second electrode being columnar; a second semiconductor layer partially provided in an upper layer portion of the first semiconductor layer, the second semiconductor layer being next to the first insulating film with the first semiconductor layer interposed; a third semiconductor layer partially provided in an upper layer portion of the second semiconductor layer; and a third electrode located higher than the upper surface of the first semiconductor layer, the third electrode overlapping a portion of the first insulating film, a portion of the first semiconductor layer, and a portion of the second semiconductor layer when viewed from above.

Abstract: A semiconductor device is disclosed. The semiconductor device includes a transistor including a source contact, a drain contact, and a channel region including an oxide semiconductor material as the channel material. At least one of the drain contact or the source contact includes a conductive material, such as ruthenium, to reduce the Schottky effects at the interface with the channel material.

Abstract: Methods for forming a semiconductor structure and semiconductor structures are described. The method comprises patterning a substrate to form a first opening and a second opening, the substrate comprising an n transistor and a p transistor, the first opening over the n transistor and the second opening over the p transistor; pre-cleaning the substrate; depositing a titanium silicide (TiSi) layer on the n transistor and on the p transistor by plasma-enhanced chemical vapor deposition (PECVD); optionally depositing a first barrier layer on the titanium silicide (TiSi) layer and selectively removing the first barrier layer from the p transistor; selectively forming a molybdenum silicide (MoSi) layer on the titanium silicide (TiSi) layer on the n transistor and the p transistor; forming a second barrier layer on the molybdenum silicide (MoSi) layer; and annealing the semiconductor structure. The method may be performed in a processing chamber without breaking vacuum.

Abstract: A semiconductor device includes a gate structure disposed over a channel region and a source/drain region. The gate structure includes a gate dielectric layer over the channel region, one or more work function adjustment material layers over the gate dielectric layer, and a metal gate electrode layer over the one or more work function adjustment material layers. The one or more work function adjustment layers includes an aluminum containing layer, and a diffusion barrier layer is disposed at at least one of a bottom portion and a top portion of the aluminum containing layer. The diffusion barrier layer is one or more of a Ti-rich layer, a Ti-doped layer, a Ta-rich layer, a Ta-doped layer and a Si-doped layer.

Abstract: A high voltage semiconductor device includes a semiconductor region of a first conductivity type having a first region and a second region, a first insulation pattern disposed over the first region of the semiconductor region to have a first thickness, a second insulation pattern disposed over the second region of the semiconductor region to have a second thickness greater than the first thickness, and a gate electrode disposed over the first and second insulation patterns to have a step structure over a boundary region between the first and second regions. The gate electrode has a doping profile that a position of a maximum projection range of impurity ions distributed in the gate electrode over the first region is located at substantially the same level as a position of a maximum projection range of impurity ions distributed in the gate electrode over the second region.

Abstract: The present disclosure generally relates to semiconductor structures and, more particularly, to gate structures and methods of manufacture. The method includes: forming a first gate structure and a second gate structure with gate materials; etching the gate materials within the second gate structure to form a trench; and depositing a conductive material within the trench so that the second gate structure has a metal composition different than the first gate structure.

Abstract: Provided are electronic devices and methods of manufacturing the same. An electronic device may include a substrate, a gate electrode on the substrate, a ferroelectric layer between the substrate and the gate electrode, and a carbon layer between the substrate and the ferroelectric layer. The carbon layer may have an sp2 bonding structure.

Abstract: A method of manufacturing a semiconductor device includes forming a fin structure in which first semiconductor layers and second semiconductor layers are alternatively stacked; forming a sacrificial gate structure over the fin structure; etching a source/drain (S/D) region of the fin structure, which is not covered by the sacrificial gate structure, thereby forming an S/D space; laterally etching the first semiconductor layers through the S/D space, thereby forming recesses; forming a first insulating layer, in the recesses, on the etched first semiconductor layers; after the first insulating layer is formed, forming a second insulating layer, in the recesses, on the first insulating layer, wherein a dielectric constant of the second insulating layer is less than that of the first insulating layer; and forming an S/D epitaxial layer in the S/D space, wherein the second insulating layer is in contact with the S/D epitaxial layer.

Abstract: A method of forming a semiconductor device includes: forming a fin protruding above a substrate; forming isolation regions on opposing sides of the fin; forming a dummy gate electrode over the fin; removing lower portions of the dummy gate electrode proximate to the isolation regions, where after removing the lower portions, there is a gap between the isolation regions and a lower surface of the dummy gate electrode facing the isolation regions; filling the gap with a gate fill material; after filling the gap, forming gate spacers along sidewalls of the dummy gate electrode and along sidewalls of the gate fill material; and replacing the dummy gate electrode and the gate fill material with a metal gate.

Abstract: The present disclosure is directed to method for the fabrication of spacer structures between source/drain (S/D) epitaxial structures and metal gate structures in nanostructure transistors. The method includes forming a fin structure with alternating first and second nanostructure elements on a substrate. The method also includes etching edge portions of the first nanostructure elements in the fin structure to form cavities. Further, depositing a spacer material on the fin structure to fill the cavities and removing a portion of the spacer material in the cavities to form an opening in the spacer material. In addition, the method includes forming S/D epitaxial structures on the substrate to abut the fin structure and the spacer material so that sidewall portions of the S/D epitaxial structures seal the opening in the spacer material to form an air gap in the spacer material.

Abstract: A semiconductor structure includes a substrate, a first epitaxial layer, a second epitaxial layer, and a transistor. The substrate includes a first pyramid protrusion, a second pyramid protrusion, a third pyramid protrusion, and a fourth pyramid protrusion. The first and second pyramid protrusions are arranged along a first direction, the second and fourth pyramid protrusions are arranged along the first direction, and the first and third pyramid protrusions are arranged along a second direction crossing the first direction. The first epitaxial layer is over the substrate and in contact with the first, second, third, and fourth pyramid protrusions. The second epitaxial layer is over the first epitaxial layer. The transistor is over the second epitaxial layer.

Abstract: A semiconductor includes a semiconductor substrate having a bottom source/drain region and a vertical semiconductor fin having a bottom end that contacts the semiconductor substrate. The semiconductor device further includes a top source/drain region on a top end of the vertical semiconductor. The top source/drain region is separated from the semiconductor substrate by the vertical semiconductor fin. The semiconductor device further includes an electrically conductive cap on an outer surface of the top source/drain region.

Abstract: A semiconductor device includes a base substrate. A first thin-film transistor is disposed on the base substrate. The first thin-film transistor includes a first input electrode, a first output electrode, a first semiconductor pattern disposed below a first insulating layer, and a first control electrode disposed on the first insulating layer and below a second insulating layer. A second thin-film transistor includes a second input electrode, a second output electrode, a second semiconductor pattern disposed on the second insulating layer, and a second control electrode disposed on an insulating pattern formed on the second semiconductor pattern and exposes a portion of the second semiconductor pattern. The first semiconductor pattern includes a crystalline semiconductor. The second semiconductor pattern incudes an oxide semiconductor. The first semiconductor pattern, the first control electrode, the second semiconductor pattern, and the second control electrode are overlapped.

Abstract: A semiconductor device includes a first electrode, a second electrode, a first semiconductor region, a second semiconductor region, a third semiconductor region, a fourth semiconductor region, a fifth semiconductor region, a first gate electrode, and a second gate electrode. The first gate electrode faces the second semiconductor region via a first insulating film. The second gate electrode faces the second semiconductor region via a second insulating film and faces the second electrode via a third insulating film contacting the second insulating film. The fifth semiconductor region includes a boundary portion that electrically contacts the second electrode. A distance between an upper surface of the fourth semiconductor region and the first electrode is greater than a distance between the boundary portion and the first electrode.

Abstract: The present invention relates to a method for assembling molecules on the surface of a two-dimensional material formed on a substrate, the method comprises: forming a spacer layer comprising at least one of an electrically insulating compound or a semiconductor compound on the surface of the two-dimensional material, depositing molecules on the spacer layer, annealing the substrate with spacer layer and the molecules at an elevated temperature for an annealing time duration, wherein the temperature and annealing time are such that at least a portion of the molecules are allowed to diffuse through the spacer layer towards the surface of the two-dimensional material to assemble on the surface of the two-dimensional material. The invention also relates to an electronic device.

Abstract: A nitride semiconductor device 1 includes a first nitride semiconductor layer 13 that constitutes an electron transit layer, a second nitride semiconductor layer 14 that is formed on the first nitride semiconductor layer and constitutes an electron supply layer, a nitride semiconductor gate layer 15 that is disposed on the second nitride semiconductor layer, has a ridge portion 15A at least at a portion thereof, and contains an acceptor type impurity, a gate electrode 4 that is disposed at least on the ridge portion of the nitride semiconductor gate layer, a source electrode 3 that is disposed on the second nitride semiconductor layer and has a source principal electrode portion 3A parallel to the ridge portion, and a drain electrode 5 that is disposed on the second nitride semiconductor layer and has a drain principal electrode portion 5A parallel to the ridge portion.

Abstract: A semiconductor device includes: a semiconductor substrate; a first gate trench and a second gate trench both extending from a first main surface of the semiconductor substrate into the semiconductor substrate; a semiconductor mesa delimited by the first and second gate trenches; and a field plate trench extending from the first main surface through the semiconductor mesa. The field plate trench includes a field plate separated from each sidewall and a bottom of the field plate trench by an air gap. The field plate is anchored to the semiconductor substrate at the bottom of the field plate trench by an electrically insulative material that occupies a space in a central part of the field plate, the electrically insulative material spanning the air gap to contact the semiconductor substrate at the bottom of the field plate trench. Methods of producing the semiconductor device are also described.

Abstract: A semiconductor device having an active portion and a gate pad portion on a semiconductor substrate includes: a first semiconductor layer of a first conductivity type; and a second semiconductor layer of a second conductivity type. The active portion has: first semiconductor regions of the first conductivity type; a first electrode provided on the first semiconductor regions; and first trenches. The gate pad portion has: a gate electrode pad provided above the second semiconductor layer; second trenches provided beneath the gate electrode pad; and second semiconductor regions of the second conductivity type, each provided in the first semiconductor layer so as to be in contact with a respective one of bottoms of the second trenches. Each of the second trenches is continuous with a respective one of the first trenches. The second semiconductor layer is continuous from the active portion to the gate pad portion.

Abstract: Structures for a laterally-diffused metal-oxide-semiconductor device and methods of forming a structure for a laterally-diffused metal-oxide-semiconductor device. The structure includes a drift well in a semiconductor substrate, source and drain regions in the semiconductor substrate, a gate dielectric layer on the semiconductor substrate, and a buffer dielectric layer on the semiconductor substrate over the drift well. The buffer dielectric layer includes a first side edge adjacent to the drain region, a second side edge adjacent to the gate dielectric layer, a first section extending from the second side edge to the first side edge, and a plurality of second sections extending from the second side edge toward the first side edge. The first section has a first thickness, and the second sections have a second thickness less than the first thickness. A gate electrode includes respective portions that overlap with the buffer dielectric layer and with the gate dielectric layer.

Abstract: Provided is a monolithic metal-insulator transition device. The monolithic metal-insulator transition device includes a substrate including a driving region and a switching region, first and second source/drain regions on the driving region, a gate electrode between the first and second source/drain regions, an inlet well region formed adjacent to an upper surface of the substrate on the switching region, a control well region having a different conductivity type from the inlet well region between the inlet well region and a lower surface of the substrate, a first wiring electrically connecting the first source/drain region and the control well region, and a second wiring electrically connecting the second source/drain region and the inlet well region.

Abstract: An apparatus includes at least one vertical transistor having a channel region. The channel region includes an upper region having a first width and a lower region below the upper region and having a second width smaller than the first width. The upper region defines at least one overhang portion extending laterally beyond the lower region. The at least one vertical transistor further includes gate electrodes at least partially vertically beneath the at least one overhang portion of the upper region of the channel region. Additional apparatuses and related systems and methods are also disclosed.

Abstract: A metal-oxide-semiconductor field-effect transistor (MOSFET) device is described herein. The MOSFET device comprises a unit cell on a silicon carbide (SiC) substrate. The unit cell comprises: a source region; a well region; and a source attachment region. The source attachment region is in contact with the source region. The source attachment region is doped using first conductivity type ions. In an embodiment, the source attachment region is doped using second conductivity type ions. The source attachment region comprises a depth shallower than a depth of source region. In an embodiment, the source attachment region comprises a depth equal to a depth of the source region. The source attachment region comprises a doping concentration lower than a doping concentration of the source region. In an embodiment, the source attachment region comprises a doping concentration equal to a doping concentration of the source region.

Abstract: Embodiments of the present invention describe a epitaxial region on a semiconductor device. In one embodiment, the epitaxial region is deposited onto a substrate via cyclical deposition-etch process. Cavities created underneath the spacer during the cyclical deposition-etch process are backfilled by an epitaxial cap layer. The epitaxial region and epitaxial cap layer improves electron mobility at the channel region, reduces short channel effects and decreases parasitic resistance.

Abstract: The present invention provides a single-gate field effect transistor device and a method for modulating the drive current thereof. The field effect transistor comprises an active layer, a source region and a drain region formed at two sides of the active layer, and a channel region located between the source region and the drain region. The field effect transistor device is configured as follows: when the transistor is turned off, a second channel of depletion-mode spontaneously forms in the channel region, and the second channel does not connect the source region and the drain region; when the transistor is turned on, the second channel and a first channel of the same polarity as the second channel are formed in the channel region; at least one of the first channel and the second channel injects carriers into the other channel so that current conduction occurs between the source and the drain and the carriers of the second channel contribute to the on-state current of the transistor.

Abstract: A ferroelectric field effect transistor (FeFET) having a double-gate structure includes a first gate electrode, a first ferroelectric material layer over the first gate electrode, a semiconductor channel layer over the first ferroelectric material layer, source and drain electrodes contacting the semiconductor channel layer, a second ferroelectric material layer over the semiconductor channel layer, and a second gate electrode over the second ferroelectric material layer.

Abstract: Vertical transport field-effect transistors are formed on active regions wherein the active regions each include a wrap-around metal silicide contact on vertically extending side walls of the active region. Such wrap-around contacts form self-aligned and reliable strapping for SRAM bottom nFET and pFET source/drain regions. Buried contacts of SRAM cells may be used to strap the wrap-around metal silicide contacts with the gates of inverters thereof. Wrap-around metal silicide contacts provide additional contacts for logic FETs and reduce parasitic bottom source/drain resistance.

Abstract: A substrate processing liquid is used to etch a substrate in which at least either a bottom wall or a side wall forming a trench structure is an etched layer made of metal or a metal compound. The substrate processing liquid includes a chemical liquid containing H2O2 molecules or HO2? functioning as an etchant for etching the metal, and a complex forming agent containing NH4+ and forming a complex with ions of the metal and is adjusted to a pH of 5 or more.