A support disk fixing apparatus which includes an upper surface to which a wafer is bonded, a lower surface, a cylindrical side surface between the upper surface and the lower surface, and a chamfered portion between the upper surface and the side surface, includes a base upon which the support disk is placed; and a fixture that is provided on the base, and that has a first surface that abuts against the side surface of the support disk and covers the side surface of the support disk, and a second surface that abuts against the chamfered portion of the support disk and covers the chamfered portion of the support disk.

A support structure for supporting a semiconductor device during a bonding operation is provided. The support structure comprises a body portion defining an upper surface configured to support a semiconductor device during a bonding operation. The upper surface defines a constraining feature for constraining at least a portion of the semiconductor device during the bonding operation.

A power semiconductor has power terminals arranged in a row at one side of the housing, with control terminals arranged in a row at the other side of the housing. The spacing between adjacent power terminals is greater than the spacing between adjacent control terminals.

An apparatus includes a first substrate having a first land and a second substrate having a second land. A first molding compound is disposed between the first substrate and the second substrate. A first semiconductor chip is disposed on the first substrate and in contact with the first molding portion. A first connector contacts the first land and a second connector contacts the second land. The second connector is disposed on the first connector. A volume of the second connector is greater than a volume of the first connector. A surface of the first semiconductor chip is exposed. The first molding compound is in contact with the second connector, and at least a portion of the second connector is surrounded by the first molding compound.

A semiconductor device effectively suppress the problem of mutual interaction occurring between an inductor element and wires positioned above the inductor element formed over the same chip. A semiconductor device includes a semiconductor substrate and a multi-wiring layer formed overlying that semiconductor substrate, and in which the multi-wiring layer includes: the inductor element and three successive wires and a fourth wire formed above the inductor element; and two shielded conductors at a fixed voltage potential and covering the inductor element as seen from a flat view, and formed between the inductor element and three successive wires and a fourth wire formed above the inductor element.

A power inverter includes a power semiconductor module that includes a power semiconductor device, a control circuit board that outputs a control signal used for controlling the power semiconductor device, a driver circuit board that outputs a driving signal used for driving the power semiconductor device, a conductive metal base plate arranged in a space between the driver circuit board and the control circuit board in which a fine and long opening portion is formed, wiring that connects the driver circuit board and the control circuit board through the opening portion and delivers the control signal to the driver circuit board, and an AC busbar that is arranged on a side opposite to the metal base plate through the driver circuit board and delivers an AC current output from the power semiconductor module to a drive motor. At least a portion of the AC busbar that faces the opening portion extends in a direction directly running in a longitudinal direction of the fine and long opening portion.

Reduction in cooling rate of a substrate having a lower temperature is suppressed because the substrate having a lower temperature is not affected by radiant heat of a substrate having a higher temperature while cooling a plurality of substrates in a cooling chamber. The substrate processing apparatus includes a load lock chamber configured to accommodate stacked substrates; a first transfer mechanism having a first transfer arm provided with a first end effector, and configured to transfer the substrates into/from the load lock chamber at a first side of the load lock chamber; a second transfer mechanism having a second transfer arm provided with a second end effector, and configured to transfer the substrates into/from the load lock chamber at a second side of the load lock chamber; a barrier installed between the substrates to be spaced apart from the substrates supported by a substrate support provided in the load lock chamber; and an auxiliary barrier unit installed between the substrate support and the barrier, wherein the auxiliary barrier unit is installed at places other than standby spaces of the end effectors.

According to one embodiment, a system for manufacturing a semiconductor device includes a spontaneous joining unit and a deformative joining unit. The spontaneous joining unit overlaps a first substrate and a second substrate and spontaneously joins mutual center portions of respective joint faces of the first substrate and the second substrate. The deformative joining unit deforms at least one peripheral portion of the respective joint faces of the first substrate and second substrate joined by the spontaneous joining unit toward the other peripheral portion and joins the mutual peripheral portions of the respective joint faces.

A mask for forming polysilicon has a first slit region where a plurality of horizontal slit patterns are arranged in the vertical direction while bearing the same width, a second slit region where a plurality of horizontal slit patterns are arranged in the vertical direction while bearing the same width, a third slit region where a plurality of horizontal slit patterns are arranged in the vertical direction while bearing the same width, and a fourth slit region where a plurality of horizontal slit patterns are arranged in the vertical direction while bearing the same width. The slit patterns arranged at the first to fourth slit regions are sequentially enlarged in width in the horizontal direction in multiple proportion to the width d of the slit pattern at the first slit region. The centers of the slit patterns arranged at the first to fourth slit regions in the horizontal direction are placed at the same line. The slit patterns arranged at the respective slit regions in the vertical direction are spaced from each other with a distance of 8*d. Alternatively, the first to fourth slit regions may be arranged in reverse order, or in the vertical direction.

A method of forming a polycrystalline silicon active layer for use in a thin film transistor is provided. The method includes forming a buffer layer over a substrate, forming an amorphous silicon layer over the buffer layer, applying a catalytic metal to a surface of the amorphous silicon layer, crystallizing the amorphous silicon layer having the catalytic metal thereon into a polycrystalline silicon layer, annealing the polycrystalline silicon layer in an N2 gas atmosphere to stabilize the polycrystalline silicon layer, etching a surface of the polycrystalline silicon layer using an etchant, and patterning the polycrystalline silicon layer to form an island-shaped active layer.

A D/A conversion circuit with a small area is provided. In the D/A conversion circuit, according to a digital signal transmitted from address lines of an address decoder, one of four gradation voltage lines is selected. A circuit including two N-channel TFTs is connected in series to a circuit including two P-channel TFT, and a circuit including the circuits connected in series to each other is connected in parallel to each of the gradation voltage lines. Further, an arrangement of the circuit including the two N-channel TFTs and the circuit including the two P-channel TFTs is reversed for every gradation voltage line. By this, the crossings of wiring lines in the D/A conversion circuit becomes small and the area can be made small.

A conduction cooled high power semiconductor laser and a method for fabricating the same are provided. The conduction cooled high power semiconductor laser comprises a heat sink (2) and one or more semiconductor laser units (1). The semiconductor laser unit consists of a laser chip (3), a substrate (4) bonded to the laser chip for heat dissipation and electrical connection, and an insulation plate (5) soldered to the substrate for insulation and heat dissipation. The semiconductor laser unit is soldered on the heat sink with the insulation plate therebetween. The semiconductor laser unit may be tested, aged, and screened in advance, and thereby the yield of the lasers can be improved and the manufacturing costs can be reduced. The laser has desirable heat dissipation performance, high reliability, and is applicable to high temperature and other complex and volatile environments.

A method of manufacturing an optical semiconductor device including: forming a mesa structure including a first conductivity type cladding layer, an active layer and a second conductivity type cladding layer in this order on a first conductivity type semiconductor substrate, an upper most surface of the mesa structure being constituted of an upper face of the second conductivity type cladding layer; growing a first burying layer burying both sides of the mesa structure at higher position than the active layer; forming an depressed face by etching both edges of the upper face of the second conductivity type cladding layer; and growing a second burying layer of the first conductivity type on the depressed face of the second conductivity type cladding layer and the first burying layer.

An intra-cavity frequency doubled OPS-laser includes a laser-resonator terminated by a plane mirror and a mirror-structure of an OPS-chip. The resonator is folded by three fold-mirrors. The fold-mirrors are supported on a vibration-isolation plate supported by isolation posts above a base-plate. The plane mirror and the mirror-structure of the OPS-chip are mounted back to back on opposite parallel surfaces of a mounting block. The mounting-block is supported on the base-plate and extends through an aperture in the vibration-isolation plate. Movement of the vibration-isolation plate with respect to the base-plate does not change the resonator length.

A method for quasi-synchronous tuning of wavelength or frequency of grating external-cavity semiconductor laser and a corresponding semiconductor laser are provided. A grating or mirror is rotated around a quasi-synchronous tuning point (Pq) as rotation center, so as to achieve the frequency selections by grating and resonance cavity in quasi-synchronous tuning, wherein the angle of the line between the quasi-synchronous tuning point (Pq) and a conventional synchronous tuning point (P0) with respect to the direction of light incident on the grating is determined according to the angle difference between the incidence angle and diffraction angle of light on the grating. According to present invention, approximately synchronous tuning of laser is achieved with a simple and flexible design.

A method for fabricating a group-III nitride semiconductor laser device stably supplies laser cavity mirrors having a low lasing threshold current through the use of a semi-polar plane. A blade 5g is forced down through a first region ER1 to keep the first region ER1 squeezed between a support member H2 and a movable member H1 together with a part of a protective sheet TF in contact with the first region ER1 while the tension generated in the area of the protective sheet TF in contact with the first region ER1 with the movable member H1 increases until the semi-polar principal surface SF at an end face EG1 of the first region ER1 tilts by a deflection angle THETA from the semi-polar principal surface SF of a second region ER2, and a force is thereby generated in the first region ER1 in a direction opposite to the direction of travel of the blade 5g toward the first region ER1. For example, an angle ALPHA is within the range of 71 degrees to 79 degrees, and the deflection angle THETA is within the range of 11 to 19.

Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.

A semiconductor laser includes a semiconductor nanowire of a first conductivity type provided over a substrate, a light emitting layer provided around the semiconductor nanowire and insulated at an upper end and a lower end thereof, a cladding layer of a second conductivity type different from the first conductivity type, the cladding layer being provided at an outer periphery of the light emitting layer, a first electrode electrically coupled to an end portion of the semiconductor nanowire, a second electrode electrically coupled to an outer periphery of the cladding layer, a first reflection mirror provided at a one-end portion side of the semiconductor nanowire, and a second reflection mirror provided at the other end portion side of the semiconductor nanowire.

A fiber coupled semiconductor device and a method of manufacturing of such a device are disclosed. The method provides an improved stability of optical coupling during assembly of the device, whereby a higher optical power levels and higher overall efficiency of the fiber coupled device can be achieved. The improvement is achieved by attaching the optical fiber to a vertical mounting surface of a fiber mount. The platform holding the semiconductor chip and the optical fiber can be mounted onto a spacer mounted on a base. The spacer has an area smaller than the area of the platform, for mechanical decoupling of thermally induced deformation of the base from a deformation of the platform of the semiconductor device. Optionally, attaching the fiber mount to a submount of the semiconductor chip further improves thermal stability of the packaged device.

A method to tune an emission wavelength of a laser diode (LD) finely is disclosed. The method first controls a temperature of the etalon filter in T1 or T2, where the transmittance of the etalon filter becomes 40 to 50%, assuming a height between the peak and the bottom of the periodic transmittance to be 100%, at the grid wavelength λ1 or λ2, respectively. Then, the temperature of the LD is adjusted such that the intensity of light emitted from the LD and transmitted through the etalon filter becomes 40 to 50%.

Novel methods and systems for miniaturized lasers are described. A photonic crystal is bonded to a silicon-on-insulator wafer. The photonic crystal includes air-holes and can include a waveguide which couples the laser output to a silicon waveguide.

A device including one or more layers with lateral regions configured to facilitate the transmission of radiation through the layer and lateral regions configured to facilitate current flow through the layer is provided. The layer can comprise a short period superlattice, which includes barriers alternating with wells. In this case, the barriers can include both transparent regions, which are configured to reduce an amount of radiation that is absorbed in the layer, and higher conductive regions, which are configured to keep the voltage drop across the layer within a desired range.

A semiconductor device that includes transistors having the same polarity consumes less power and can prevent a decrease in amplitude of a potential output. The semiconductor device includes a first wiring having a first potential, a second wiring having a second potential, a third wiring having a third potential, a first transistor and a second transistor having the same polarity, and a plurality of third transistors for selecting supply of the first potential to gates of the first transistor and the second transistor or supply of the third potential to the gates of the first transistor and the second transistor and for selecting whether to supply one potential to drain terminals of the first transistor and the second transistor. A source terminal of the first transistor is connected to the second wiring, and a source terminal of the second transistor is connected to the third wiring.

A semiconductor device which shifts a low-level signal is provided. In an example, a first transistor including a first terminal electrically connected to a first wiring and a second terminal electrically connected to a second wiring, a second transistor including a first terminal electrically connected to a third wiring and a second terminal electrically connected to the second wiring, a third transistor including a first terminal electrically connected to a fourth wiring and a second terminal electrically connected to a gate of the second transistor, a fourth transistor including a first terminal electrically connected to a fifth wiring, a second terminal electrically connected to a gate of the third transistor, and a gate electrically connected to a sixth wiring, and a first switch including a first terminal electrically connected to the third wiring and a second terminal electrically connected to a gate of the first transistor are included.

A semiconductor integrated circuit includes: a main-interconnect to which supply voltage or reference voltage is applied; a plurality of sub-interconnects; a plurality of circuit cells configured to be connected to the plurality of sub-interconnects; a power supply switch cell configured to control, in accordance with an input control signal, connection and disconnection between the main-interconnect and the sub-interconnect to which a predetermined one of the circuit cells is connected, of the plurality of sub-interconnects; and an auxiliary interconnect configured to connect the plurality of sub-interconnects to each other.

An isolator circuit capable of two-way electrical disconnection and a semiconductor device including the isolator circuit are provided. A data holding portion is provided in an isolator circuit without the need for additional provision of a data holding portion outside the isolator circuit, and data which is to be input to a logic circuit that is in an off state at this moment is stored in the data holding portion. The data holding portion may be formed using a transistor with small off-state current and a buffer. The buffer can include an inverter circuit and a clocked inverter circuit.

Disclosed herein is a device that includes first and second buffer circuits connected to a data terminal and a first control circuit controlling the first and second buffer circuits. The first control circuit receives n pairs of first and second internal data signals complementary to each other from 2n input signal lines and outputs a pair of third and fourth internal data signals complementary to each other to first and second output signal lines, where n is a natural number more than one. The first and second buffer circuits are controlled based on the third and fourth internal data signals such that one of the first and second buffer circuits turns on and the other of the first and second buffer circuits turns off.

A semiconductor device includes an internal circuit, a power supply control circuit which controls supply of a power supply to the internal circuit upon receipt of a first control signal, and a control signal generation circuit which outputs the first control signal upon receipt of a second control signal. The control signal generation circuit does not deactivate the first control signal when an inactive period of the second control signal is equal to or less than a first period and deactivates the first control signal when the inactive period of the second control signal is more than the first period.

An embodiment of this invention uses a massive parallel interconnect fabric (MPIF) at the flipped interface of a core die substrate (having the core logic blocks) and a context die (used for in circuit programming/context/customization of the core die substrate), to produce ASIC-like density and FPGA-like flexibility/programmability, while reducing the time and cost for development and going from prototyping to production, reducing cost per die, reducing or eliminating NRE, and increasing performance. Other embodiments of this invention enable debugging complex SoC through large contact points provided through the MPIF, provide for multi-platform functionality, and enable incorporating FGPA core in ASIC platform through the MPIF. Various examples are also given for different implementations.

A semiconductor integrated circuit including: a circuit block having an internal voltage line; an annular rail line forming a closed annular line around the circuit block and supplied with one of a power supply voltage and a reference voltage; and a plurality of switch blocks arranged around the circuit block along the annular rail line, the plurality of switch blocks each including a voltage line segment forming a part of the annular rail line and a switch for controlling connection and disconnection between the voltage line segment and the internal voltage line.

An integrated structure of compound semiconductor devices is disclosed. The integrated structure comprises from bottom to top a substrate, a first epitaxial layer, an etching-stop layer, a second epitaxial layer, a sub-collector layer, a collector layer, a base layer, and an emitter layer, in which the first epitaxial layer is a p-type doped layer, the second epitaxial layer is an n-type graded doping layer with a gradually increased or decreased doping concentration, and the sub-collector layer is an n-type doped layer. The integrated structure can be used to form an HBT, a varactor, or an MESFET.

A current output control device is provided that includes: a current cell array section including plural current cell circuits that are each connected in parallel between a first terminal (power source) and a second terminal (ground) that connect between the first terminal and the second terminal in by operation ON so as to increase control current flowing between the first terminal and the second terminal; and a code conversion section (decoder) that generates signals (row codes, column codes) to ON/OFF control current cells so as to change the number of current cells that connect the first terminal and the second terminal according to change in an externally input code and that inputs the generated signals to the current cell array section.

The present invention relates generally to a semiconductor device and, more specifically, to optimizing the creep-age distance of the power semiconductor device and a preparation method thereof. The power semiconductor device includes a chip mounting unit with a die paddle and a plurality of leads arranged side by side located close to one side edge of the die paddle in a non-equidistant manner, a semiconductor chip attached on the die paddle, and a plastic packaging body covering the die paddle, the semiconductor chip, where the plastic packing body includes a plastic extension portion covering at least a part of a lead shoulder of a lead to obtain better electrical safety distance between the terminals of the semiconductor device, thus voltage creep-age distance of the device is increased.

Some implementations provide a structure that includes a first package substrate, a first component, a second package substrate, a second component, and a third component. The first package substrate has a first area. The first component has a first height and is positioned on the first area. The second package substrate is coupled to the first package substrate. The second package substrate has second and third areas. The second area of the second package substrate vertically overlaps with the first area of the first package substrate The third area of the second package substrate is non-overlapping with the first area of the first package substrate. The second component has a second height and is positioned on the second area. The third component is positioned on the third area. The third component has a third height that is greater than each of the first and second heights.

The stack package includes a first semiconductor package and a second semiconductor package. The first semiconductor package includes a first substrate having a first modulus and at least one semiconductor chip mounted on the first substrate. The second semiconductor package stacked on the first semiconductor package and includes a second substrate having a second modulus and at least one semiconductor chip mounted on the second substrate. The second modulus is less than the first modulus. Even in the event that the first semiconductor package is under severe warpage due to a temperature change, the flexible second substrate, which includes e.g., polyimide or poly ethylene terephthalate, of the second semiconductor package may be less sensitive to the temperature change, thereby improving reliability of the stack package.

A through silicon via with sidewall roughness and methods of manufacturing the same are disclosed. The method includes forming a via in a substrate and roughening a sidewall of the via by depositing material within the via. The method further includes removing a backside of the substrate to form a through via with a roughened sidewall structure.

Systems, manufactures, methods and/or techniques for a merged fiducial for chip packages are described. According to some embodiments, an integrated circuit package may include a package substrate having a first side and a second side, a plurality of conductive traces coupled to the first side and a plurality of balls disposed on the second side. The balls may be adapted to electrically connect the laminate package to a circuit board. The integrated circuit package may include a plurality of ball pads disposed on the second side, the ball pads being adapted to electrically connect the plurality of balls to the plurality of conductive traces. One or more of the ball pads may be uniquely shaped when compared to the rest of the plurality of ball pads, optionally, to serve as a fiducial to designate an A1 pin or ball of the laminate package.

A base at least one principal plane of which is a nitride is prepared for use in epitaxial growth. The base is placed on a susceptor in an epitaxial growth reactor and heated to a predetermined temperature (step A). The heating is started with inactive, nitrogen gas being supplied into the reactor. Then, active, NH3 gas is supplied. Then, a growth step (step B) of a first nitride semiconductor layer is started without an intervening step of thermally cleaning the principal nitride plane of the base. In step B, the first nitride semiconductor layer is epitaxially grown on a principal nitride plane of a base without supply of an Si source material. Then, a relatively thick, second nitride semiconductor layer is epitaxially grown on the first nitride semiconductor layer by supplying an n-type dopant source material (step C).

In manufacturing an LSI, or semiconductor integrated circuit device, the step of assembling device (such as resin sealing step) is normally followed by a voltage-application test in an environment of high temperature (e.g., from 85 to 130° C.) and high humidity (e.g., about 80% RH). It has been found that separation of a titanium nitride anti-reflection film from an upper film and generation of cracks in the titanium nitride film at an upper surface edge part of the aluminum-based bonding pad applied with a positive voltage in the test is caused by an electrochemical reaction due to moisture incoming through the sealing resin and the like to generate oxidation and bulging of the titanium nitride film. These problems are addressed by removing the titanium nitride film over the pad in a ring or slit shape at peripheral area of the aluminum-based bonding pad.

A larger substrate can be used, and a transistor having a desirably high field-effect mobility can be manufactured through formation of an oxide semiconductor layer having a high degree of crystallinity, whereby a large-sized display device, a high-performance semiconductor device, or the like can be put into practical use. A first multi-component oxide semiconductor layer is formed over a substrate and a single-component oxide semiconductor layer is formed thereover; then, crystal growth is carried out from a surface to an inside by performing heat treatment at 500° C. to 1000° C. inclusive, preferably 550° C. to 750° C. inclusive so that a first multi-component oxide semiconductor layer including single crystal regions and a single-component oxide semiconductor layer including single crystal regions are formed; and a second multi-component oxide semiconductor layer including single crystal regions is stacked over the single-component oxide semiconductor layer including single crystal regions.

A first impurity region is formed by ion implantation through a first opening formed in a mask layer. By depositing a spacer layer on an etching stop layer on which the mask layer has been provided, a mask portion having the mask layer and the spacer layer is formed. By anisotropically etching the spacer layer, a second opening surrounded by a second sidewall is formed in the mask portion. A second impurity region is formed by ion implantation through the second opening. An angle of the second sidewall with respect to a surface is 90°±10° across a height as great as a second depth. Thus, accuracy in extension of an impurity region can be enhanced.

A semiconductor device has a semiconductor wafer with a plurality of contact pads. A first insulating layer is formed over the semiconductor wafer and contact pads. A portion of the first insulating layer is removed, exposing a first portion of the contact pads, while leaving a second portion of the contact pads covered. An under bump metallization layer and a plurality of bumps is formed over the contact pads and the first insulating layer. A second insulating layer is formed over the first insulating layer, a sidewall of the under bump metallization layer, sidewall of the bumps, and upper surface of the bumps. A portion of the second insulating layer covering the upper surface of the bumps is removed, but the second insulating layer is maintained over the sidewall of the bumps and the sidewall of the under bump metallization layer.

It is an object to provide a semiconductor device including a thin film transistor with favorable electric properties and high reliability, and a method for manufacturing the semiconductor device with high productivity. In an inverted staggered (bottom gate) thin film transistor, an oxide semiconductor film containing In, Ga, and Zn is used as a semiconductor layer, and a buffer layer formed using a metal oxide layer is provided between the semiconductor layer and a source and drain electrode layers. The metal oxide layer is intentionally provided as the buffer layer between the semiconductor layer and the source and drain electrode layers, whereby ohmic contact is obtained.

A process for preparing a semiconductor structure for mounting to a carrier is disclosed. The process involves causing a support material to substantially fill a void defined by surfaces formed in the semiconductor structure and causing the support material to solidify sufficiently to support the semiconductor structure when mounted to the carrier.

A III-N device is described with a III-N material layer, an insulator layer on a surface of the III-N material layer, an etch stop layer on an opposite side of the insulator layer from the III-N material layer, and an electrode defining layer on an opposite side of the etch stop layer from the insulator layer. A recess is formed in the electrode defining layer. An electrode is formed in the recess. The insulator can have a precisely controlled thickness, particularly between the electrode and III-N material layer.

The object of the invention is to provide a method for fabricating a semiconductor device having a peeled layer bonded to a base material with curvature. Particularly, the object is to provide a method for fabricating a display with curvature, more specifically, a light emitting device having an OLED bonded to a base material with curvature. An external force is applied to a support originally having curvature and elasticity, and the support is bonded to a peeled layer formed over a substrate. Then, when the substrate is peeled, the support returns into the original shape by the restoring force, and the peeled layer as well is curved along the shape of the support. Finally, a transfer object originally having curvature is bonded to the peeled layer, and then a device with a desired curvature is completed.

Disclosed is a semiconductor device including an oxide semiconductor film. A first oxide semiconductor film with a thickness of greater than or equal to 2 nm and less than or equal to 15 nm is formed over a gate insulating layer. First heat treatment is performed so that crystal growth from a surface of the first oxide semiconductor film to the inside thereof is caused, whereby a first crystal layer is formed. A second oxide semiconductor film with a thickness greater than that of the first oxide semiconductor film is formed over the first crystal layer. Second heat treatment is performed so that crystal growth from the first crystal layer to a surface of the second oxide semiconductor film is caused, whereby a second crystal layer is formed. Further, oxygen doping treatment is performed on the second crystal layer.

To provide a method by which a semiconductor device including a thin film transistor with excellent electric characteristics and high reliability is manufactured with a small number of steps. After a channel protective layer is formed over an oxide semiconductor film containing In, Ga, and Zn, a film having n-type conductivity and a conductive film are formed, and a resist mask is formed over the conductive film. The conductive film, the film having n-type conductivity, and the oxide semiconductor film containing In, Ga, and Zn are etched using the channel protective layer and gate insulating films as etching stoppers with the resist mask, so that source and drain electrode layers, a buffer layer, and a semiconductor layer are formed.

An object is to provide a thin film transistor and a method for manufacturing the thin film transistor including an oxide semiconductor with a controlled threshold voltage, high operation speed, a relatively easy manufacturing process, and sufficient reliability. An impurity having influence on carrier concentration in the oxide semiconductor layer, such as a hydrogen atom or a compound containing a hydrogen atom such as H2O, may be eliminated. An oxide insulating layer containing a large number of defects such as dangling bonds may be formed in contact with the oxide semiconductor layer, such that the impurity diffuses into the oxide insulating layer and the impurity concentration in the oxide semiconductor layer is reduced. The oxide semiconductor layer or the oxide insulating layer in contact with the oxide semiconductor layer may be formed in a deposition chamber which is evacuated with use of a cryopump whereby the impurity concentration is reduced.

A method for producing a Ga-containing group III nitride semiconductor having reduced threading dislocation is disclosed. A buffer layer in a polycrystal, amorphous or polycrystal/amorphous mixed state, comprising AlGaN is formed on a substrate. The substrate having the buffer layer formed thereon is heat-treated at a temperature higher than a temperature at which a single crystal of a Ga-containing group III nitride semiconductor grows on the buffer layer and at a temperature that the Ga-containing group III nitride semiconductor does not grow, to reduce crystal nucleus density of the buffer layer as compared with the density before the heat treatment. After the heat treatment, the temperature of the substrate is decreased to a temperature that the Ga-containing group III nitride semiconductor grows, the temperature is maintained, and the Ga-containing group III nitride semiconductor is grown on the buffer layer.