Abstract: Embodiments include methods of making semiconductor devices with low leakage Schottky contacts. An embodiment includes providing a partially completed semiconductor device including a substrate, a semiconductor on the substrate, and a passivation layer on the semiconductor, and using a first mask, locally etching the passivation layer to expose a portion of the semiconductor. Without removing the first mask, a Schottky contact is formed of a first material on the exposed portion of the semiconductor, and the mask is removed. Using a further mask, a step-gate conductor of a second material electrically coupled to the Schottky contact is formed overlying parts of the passivation layer adjacent to the Schottky contact. By minimizing the process steps between opening the Schottky contact window in the passivation layer and forming the Schottky contact material in this window, the gate leakage of a resulting field effect device having a Schottky gate may be substantially reduced.

Abstract: A low leakage current transistor (2) is provided which includes a GaN-containing substrate (11-14) covered by a passivation surface layer (17) in which a T-gate electrode with sidewall extensions (20) is formed and coated with a multi-level passivation layer (30-32) which includes an intermediate etch stop layer (31) which is used to define a continuous multi-region field plate (33) having multiple distances between the bottom surface of the field plate 33 and the semiconductor substrate in the gate-drain region of the transistor.

Abstract: In some embodiments, a metal insulator semiconductor heterostructure field effect transistor (MISHFET) is disclosed that has a source, a drain, an insulation layer, a gate dielectric, and a gate. The source and drain are on opposing sides of a channel region of a channel layer. The channel region is an upper portion of the channel layer. The channel layer comprises gallium nitride. The insulation layer is over the channel layer and has a first portion and a second portion. The first portion is nearer the drain than the source and has a first thickness. The second portion is nearer the source than drain and has the first thickness. The insulation layer has an opening through the insulation layer. The opening is between the first portion and the second portion.

Abstract: A semiconductor device includes a semiconductor substrate configured to include a channel, a gate supported by the semiconductor substrate to control current flow through the channel, a first dielectric layer supported by the semiconductor substrate and including an opening in which the gate is disposed, and a second dielectric layer disposed between the first dielectric layer and a surface of the semiconductor substrate in a first area over the channel. The second dielectric layer is patterned such that the first dielectric layer is disposed on the surface of the semiconductor substrate in a second area over the channel.

Abstract: A semiconductor device includes a semiconductor substrate configured to include a channel, first and second ohmic contacts supported by the semiconductor substrate, in ohmic contact with the semiconductor substrate, and spaced from one another for current flow between the first and second ohmic contacts through the channel, and first and second dielectric layers supported by the semiconductor substrate. At least one of the first and second ohmic contacts extends through respective openings in the first and second dielectric layers. The second dielectric layer is disposed between the first dielectric layer and a surface of the semiconductor substrate, and the second dielectric layer includes a wet etchable material having an etch selectivity to a dry etchant of the first dielectric layer.

Abstract: An electronic device having a conductive substrate via extending between a conductor on a rear face and a conductor over a front face of the substrate includes a multi-layered etch-stop beneath the front surface conductor. The etch-stop permits use of a single etchant to penetrate both the substrate and any overlying semiconductor and/or dielectric without attacking the overlying front surface conductor. This is especially important when the semiconductor and dielectric are so thin as to preclude changing etchants when these regions are reached during etching. The etch-stop is preferably a stack of N?2 pairs of sub-layers, where a first sub-layer comprises stress relieving and/or adhesion promoting material (e.g., Ti), and the second sub-layer comprises etch resistant material (e.g., Ni). In a further embodiment, where the device includes field effect transistors having feedback sensitive control gates, the etch-stop material is advantageously used to form gate shields.

Abstract: Embodiments include semiconductor devices with low leakage Schottky contacts. An embodiment is formed by providing a partially completed semiconductor device including a substrate, a semiconductor on the substrate, and a passivation layer on the semiconductor, and using a first mask, locally etching the passivation layer to expose a portion of the semiconductor. Without removing the first mask, a Schottky contact is formed of a first material on the exposed portion of the semiconductor, and the first mask is removed. Using a further mask, a step-gate conductor of a second material electrically coupled to the Schottky contact is formed overlying parts of the passivation layer adjacent to the Schottky contact. By minimizing the process steps between opening the Schottky contact window in the passivation layer and forming the Schottky contact material in this window, the gate leakage of a resulting field effect device having a Schottky gate may be substantially reduced.

Abstract: A low leakage current switch device (110) is provided which includes a GaN-on-Si substrate (11-13) covered by a passivation surface layer (43) in which a T-gate electrode with sidewall extensions (48) is formed and coated with a conformal passivation layer (49) so that the T-gate electrode sidewall extensions are spaced apart from the underlying passivation surface layer (43) by the conformal passivation layer (49).

Abstract: An electronic device having a conductive substrate via extending between a conductor on a rear face and a conductor over a front face of the substrate includes a multi-layered etch-stop beneath the front surface conductor. The etch-stop permits use of a single etchant to penetrate both the substrate and any overlying semiconductor and/or dielectric without attacking the overlying front surface conductor. This is especially important when the semiconductor and dielectric are so thin as to preclude changing etchants when these regions are reached during etching. The etch-stop is preferably a stack of N?2 pairs of sub-layers, where a first sub-layer comprises stress relieving and/or adhesion promoting material (e.g., Ti), and the second sub-layer comprises etch resistant material (e.g., Ni). In a further embodiment, where the device includes field effect transistors having feedback sensitive control gates, the etch-stop material is advantageously used to form gate shields.

Abstract: In some embodiments, a metal insulator semiconductor heterostructure field effect transistor (MISHFET) is disclosed that has a source, a drain, an insulation layer, a gate dielectric, and a gate. The source and drain are on opposing sides of a channel region of a channel layer. The channel region is an upper portion of the channel layer. The channel layer comprises gallium nitride. The insulation layer is over the channel layer and has a first portion and a second portion. The first portion is nearer the drain than the source and has a first thickness. The second portion is nearer the source than drain and has the first thickness. The insulation layer has an opening through the insulation layer. The opening is between the first portion and the second portion.

Abstract: An electronic device (50) having a conductive substrate via (70) extending between a conductor (39) on a rear face (22) and a conductor (58) over the front surface (23) of the substrate (21) includes a multi-layered etch-stop (56, 56-2) beneath the front surface conductor (58). The etch-stop (56, 56-2) permits use of a single etchant to penetrate both the substrate (21) and any overlying semiconductor (44) and/or dielectric (34) without attacking the overlying front surface conductor (58). This is especially important when the semiconductor (44) and dielectric (34) are so thin as to preclude changing etchants when these regions are reached during etching. The etch-stop (56) is preferably a stack (63, 73) of N?2 pairs (62-i) of sub-layers (62-i1, 62-i2) in either order, where a first sub-layer (62-i1) comprises stress relieving and/or adhesion promoting material (e.g., Ti), and the second sub-layer (62-i2) comprises etch resistant material (e.g., Ni).

Abstract: Semiconductor devices are provided with dual passivation layers. A semiconductor layer is formed on a substrate and covered by a first passivation layer (PL-1). PL-1 and part of the semiconductor layer are etched to form a device mesa. A second passivation layer (PL-2) is formed over PL-1 and exposed edges of the mesa. Vias are etched through PL-1 and PL-2 to the semiconductor layer where source, drain and gate are to be formed. Conductors are applied in the vias for ohmic contacts for the source-drain and a Schottky contact for the gate. Interconnections over the edges of the mesa couple other circuit elements. PL-1 avoids adverse surface states near the gate and PL-2 insulates edges of the mesa from overlying interconnections to avoid leakage currents. An opaque alignment mark is desirably formed at the same time as the device to facilitate alignment when using transparent semiconductors.

Abstract: A bulk GaN layer is on a first surface of a substrate, wherein the bulk GaN layer has a GaN transistor region and a bulk acoustic wave (BAW) device region. A source/drain layer is over a first surface of the bulk GaN layer in the GaN transistor region. A gate electrode is formed over the source/drain layer. A first BAW electrode is formed over the first surface of the bulk GaN layer in the BAW device region. An opening is formed in a second surface of the substrate, opposite the first surface of the substrate, which extends through the substrate and exposes a second surface of the bulk GaN layer, opposite the first surface of the bulk GaN layer. A second BAW electrode is formed within the opening over the second surface of the bulk GaN layer.

Abstract: An electronic device (50) having a conductive substrate via (70) extending between a conductor (39) on a rear face (22) and a conductor (58) over the front surface (23) of the substrate (21) includes a multi-layered etch-stop (56, 56-2) beneath the front surface conductor (58). The etch-stop (56, 56-2) permits use of a single etchant to penetrate both the substrate (21) and any overlying semiconductor (44) and/or dielectric (34) without attacking the overlying front surface conductor (58). This is especially important when the semiconductor (44) and dielectric (34) are so thin as to preclude changing etchants when these regions are reached during etching. The etch-stop (56) is preferably a stack (63, 73) of N?2 pairs (62-i) of sub-layers (62-i1, 62-i2) in either order, where a first sub-layer (62-i1) comprises stress relieving and/or adhesion promoting material (e.g., Ti), and the second sub-layer (62-i2) comprises etch resistant material (e.g., Ni).

Abstract: A dielectric layer for a gallium nitride transistor is disclosed. In one example, the dielectric layer has a hydrogen content of less than or equal to 10% by atomic percentage. In one example, both a dielectric layer formed before a conductive electrode of the transistor and a dielectric layer formed after the conductive elective electrode have a hydrogen content of less than or equal to 10% by atomic percentage. In one example, the dielectric layer formed before the conductive electrode is formed by a LPCVD process and the dielectric layer formed after the conductive electrode is formed by a sputtering process.

Abstract: Semiconductor devices (61) and methods (80-89, 100) are provided with dual passivation layers (56, 59). A semiconductor layer (34) is formed on a substrate (32) and covered by a first passivation layer (PL-1) (56). PL-1 (56) and part (341) of the semiconductor layer (34) are etched to form a device mesa (35). A second passivation layer (PL-2) (59) is formed over PL-1 (56) and exposed edges (44) of the mesa (35). Vias (90, 92, 93) are etched through PL-1 (56) and PL-2 (59) to the semiconductor layer (34) where source (40), drain (42) and gate are to be formed. Conductors (41, 43, 39) are applied in the vias (90, 92, 93) for ohmic contacts for the source-drain (40, 42) and a Schottky contact (39) for the gate. Interconnections (45, 47) over the edges (44) of the mesa (35) couple other circuit elements. PL-1 (56) avoids adverse surface states (52) near the gate and PL-2 (59) insulates edges (44) of the mesa (35) from overlying interconnections (45, 47) to avoid leakage currents (46).

Abstract: Embodiments include semiconductor devices with low leakage Schottky contacts. An embodiment is formed by providing a partially completed semiconductor device including a substrate, a semiconductor on the substrate, and a passivation layer on the semiconductor, and using a first mask, locally etching the passivation layer to expose a portion of the semiconductor. Without removing the first mask, a Schottky contact is formed of a first material on the exposed portion of the semiconductor, and the first mask is removed. Using a further mask, a step-gate conductor of a second material electrically coupled to the Schottky contact is formed overlying parts of the passivation layer adjacent to the Schottky contact. By minimizing the process steps between opening the Schottky contact window in the passivation layer and forming the Schottky contact material in this window, the gate leakage of a resulting field effect device having a Schottky gate may be substantially reduced.

Abstract: Methods and apparatus are described for semiconductor devices. A method comprises providing a partially completed semiconductor device including a substrate, a semiconductor on the substrate, and a passivation layer on the semiconductor, and using a first mask, locally etching the passivation layer to expose a portion of the semiconductor, and without removing the first mask, forming a Schottky contact of a first material on the exposed portion of the semiconductor, then removing the first mask, and using a further mask, forming a step-gate conductor of a second material electrically coupled to the Schottky contact and overlying parts of the passivation layer adjacent to the Schottky contact. By minimizing the process steps between opening the Schottky contact window in the passivation layer and forming the Schottky contact material in this window, the gate leakage of a resulting field effect device having a Schottky gate may be substantially reduced.

Abstract: A bulk GaN layer is on a first surface of a substrate, wherein the bulk GaN layer has a GaN transistor region and a bulk acoustic wave (BAW) device region. A source/drain layer is over a first surface of the bulk GaN layer in the GaN transistor region. A gate electrode is formed over the source/drain layer. A first BAW electrode is formed over the first surface of the bulk GaN layer in the BAW device region. An opening is formed in a second surface of the substrate, opposite the first surface of the substrate, which extends through the substrate and exposes a second surface of the bulk GaN layer, opposite the first surface of the bulk GaN layer. A second BAW electrode is formed within the opening over the second surface of the bulk GaN layer.

Abstract: A passivation layer of AlN is deposited on a GaN channel HFET using molecular beam epitaxy (MBE). Using MBE, many other surfaces may also be coated with AlN, including silicon devices, nitride devices, GaN based LEDs and lasers as well as other semiconductor systems. The deposition is performed at approximately 150° C. and uses alternating beams of aluminum and remote plasma RF nitrogen to produce an approximately 500 ? thick AlN layer.