The phase-shifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite. Destructive interference between waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution with which such patterns can be projected. A simple theory predicts a near doubling of resolution for illumination with partial incoherence σ < 0.3, and substantial improvements in resolution for σ < 0.7. Initial results obtained with a phase-shifting mask patterned with typical device structures by electron-beam lithography and exposed using a Mann 4800 10× tool reveals a 40-percent increase in usuable resolution with some structures printed at a resolution of 1000 lines/mm. Phase-shifting mask structures can be used to facilitate proximity printing with larger gaps between mask and wafer. Theory indicates that the increase in resolution is accompanied by a minimal decrease in depth of focus. Thus the phase-shifting mask may be the most desirable device for enhancing optical lithography resolution in the VLSI/VHSIC era.

Improving resolution in photolithography with a phase-shifting mask

With the increasing requirements for microelectromechanical systems (MEMS) regarding stability, miniaturization and integration, novel materials such as wide band gap semiconductors are attracting more attention. Polycrystalline SiC has first been implemented into Si micromachining techniques, mainly as etch stop and protective layers. However, the outstanding properties of wide band gap semiconductors offer many more possibilities for the implementation of new functionalities. Now, a variety of technologies for SiC and group III nitrides exist to fabricate fully wide band gap semiconductor based MEMS. In this paper we first review the basic technology (deposition and etching) for group III nitrides and SiC with a special focus on the fabrication of three-dimensional microstructures relevant for MEMS. The basic operation principle for MEMS with wide band gap semiconductors is described. Finally, the first applications of SiC based MEMS are demonstrated, and innovative MEMS and NEMS devices are reviewed.

http://iopscience.iop.org/article/10.1088/0022-3727/40/20/S19/pdf

Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications

A SAW filter comprising a piezoelectric substrate and at least two filter tracks formed on the substrate, each having at least two IDT electrodes for input and output. The two filter tracks have substantially the same phase within a pass band, while it is substantially inverse-phased outside the pass band. For realizing the above-described conditions, input IDT electrode of one filter track is connected in parallel with input IDT electrode of the other filter track, while output IDT electrode of one filter track is connected in parallel with output IDT electrode of the other filter track. Furthermore, frequency values of said two filter tracks substantially coincide at a point 3dB lower from the peak transfer function value. Thus the above-configured SAW filter of the present invention is smaller in the overall size and offers a broad pass band and a steep attenuation characteristic.

Surface-acoustic-wave filter

An enhanced backscatter RF-ID tag reader system and multiprotocol RF tag reader system is provided. In a multiprotocol mode, the system emits a non-stationary interrogation signal, and decodes a phase modulated backscatter signal by detecting a stronger phase component from quadrature phase representations or determining phase transition edges in a phase of a received signal. The RF tag reader system predicts or follows the phase of the backscatter signal, thereby avoiding interference from nulls in the received signal waveform due to the non-stationary interrogation signal, relative movement or environmental effects. An acoustic RF-ID tag detection system detects the reradiated signal corresponding to respective transformation of a signal in the tag. Detection of either type of RF-ID tags therefore is possible, and the absence of any tag or absence of any valid tag also determined.

Dual mode transmitter-receiver and decoder for RF transponder tags

A dual-band antenna matching system and a method for dual-band impedance matching are provided. The method comprises: accepting a frequency-dependent impedance from an antenna; and, selectively supplying a conjugate impedance match for the antenna at either a first and a second communication band, or a third and a fourth communication band. More specifically, the method comprises: tuning a first tuning circuit to a first frequency; and, simultaneously tuning a second tuning circuit to a second frequency. In response, a conjugate match is supplied to the antenna in the first communication band in response to the first frequency. Simultaneously, the antenna is matched in the second communication band in response to the second frequency. When the first tuning circuit is tuned to a third frequency, and the second tuning circuit is tuned to a fourth frequency, then conjugate matches are supplied for the third and fourth communication bands, responsive to the third and fourth frequencies, respectively.

System and method for dual-band antenna matching

A radio frequency filter that can be miniaturized is provided. The radio frequency filter has a ladder-type resonator filter, a first terminal, a second terminal, a serial capacitance, a parallel capacitance, a serial inductance, and a parallel inductance. In the ladder-type resonator filter, a plurality of first surface acoustic wave resonators or first film bulk acoustic resonators are connected in a ladder circuit configuration. The serial inductance and the parallel capacitance are connected between the ladder-type resonator filter and the first terminal. The serial capacitance and the parallel inductance are connected between the ladder-type resonator filter and the second terminal.

Radio frequency filter, radio frequency circuit, antenna duplexer and radio terminal

A high frequency module is disclosed which comprises a high frequency device in a package, a circuit formed on a flexible substrate in the package, the circuit, the high frequency device and input/output terminals of the package being connected electrically.

High frequency module including a flexible substrate

In a high frequency circuit device, inductive circuit elements constituting a matching circuit are constructed of so-called helical coils having fine metal wires wound in a hollow solenoid form, which are disposed inside a package in which a high frequency circuit element such as a surface acoustic wave element or the like is mounted The high frequency circuit device may be utilized in equipment such as wireless communication equipment for reducing the size as well as providing good high frequency characteristics

High-frequency circuit device

In order to reduce the size of a duplex radio communication transceiver such as a mobile telephone, this transceiver is constructed of a transmitting and receiving duplexer, a filter to be coupled to the duplexer, an amplifier for amplifying a signal received, and a filter to be connected with the output of the amplifier. All the filters are made of acoustic surface wave filters, and all the circuits are mounted on a single metallic substrate and sealed by means of a metallic casing into a module. The transceiver thus constructed has a volume which is one tenth as small as that of the device of the same kind according to the prior art.

Duplex radio communication transceiver

A surface acoustic wave device is disclosed for use in a communication apparatus where the surface acoustic wave device has a multiple of surface acoustic wave elements with different filter characteristics formed on mutually distinct piezoelectric substrates. The different filter characteristics combine to form filters having desired filter characteristics.

Mitsutaka Hikita

Papers

Radio frequency filter, radio frequency circuit, antenna duplexer and radio terminal

High frequency module including a flexible substrate

High-frequency circuit device

Duplex radio communication transceiver

Surface acoustic wave filter device formed on a plurality of piezoelectric substrates