Laser etching of a substrate (28) in a liquid (12) is accomplished by laser induced sonic cavitation at the substrate surface. The preferred substrate (28) is laser (22) energy absorbing and has a finite melting temperature. The preferred liquid (12) is an organic or inorganic inert liquid which does not chemically react with the substrate (28) at room temperature. The laser (22) is preferably a copper vapor laser but a chopped beam cw argon ion laser or a YAG laser adjusted to a low power output sufficient to avoid the formation of a recast layer can also be used. The laser (22) parameters are adjusted for causing the growth and collapse of bubbles at the substrate surface. The laser etching has particular application in the fabrication of rails (46) in magnetic head sliders and dicing of Al₂O₃-TiC, TiC, SiC, Si/SiO₂, and laser energy absorbing metal and metal oxides.

Laser etching of materials in liquids

A thin film transistor is connected to a picture element displaying electrode formed on an insulating base plate so that a voltage is applied to the electrode. The thin film transistor comprises a gate electrode, one or more drain electrodes connected to the picture element displaying electrode and a source bus line which -applies a voltage to one or more source electrodes connected thereto, the source bus line functioning by itself as a source electrode, wherein the one drain electrode is formed between the source bus line and one of the one source electrode connected to the source bus line, or between the source electrodes adjacent to each other.

Thin film transistor, method of repairing the thin film transistor and displaying apparatus having the thin film transistor

In an interconnection film cutting method and apparatus therefor according to the present invention, a laser beam having a pulse width of 10 -9 second or less is illuminated on a desired portion of the interconnection pattern of a semiconductor device, such as a link used for redundant operation of a defective bit in, for example, a LSI memory, or on a desired portion of the interconnection pattern of a large-scaled interconnection substrate through a transmission type liquid crystal mask in the form of a desired pattern so as to cut the interconnection pattern without damaging a layer disposed below the interconnection pattern.

Method of cutting interconnection pattern with laser and apparatus thereof

An integrated circuit device including a link point for electrically connecting a plurality of metal layers, comprising a first metal layer, a link insulating layer, a second metal layer and diffusion barrier layers between the link insulator layer and each of the first metal layer and the second metal layer. The metal layers are connected by exposing the link point to a low-power laser for a relatively long pulse width.

Method of making a conductive path in multi-layer metal structures by low power laser beam

Methods and apparatus for an analog-to-digital converter (ADC) with reduced comparator-hysteresis effects One embodiment uses a charge-redistribution ADC One method performs an initial coarse analog-to-digital conversion to avoid overdriving an analog voltage comparator One such method includes a redundant capacitor in an array of charge-redistribution capacitors used in the ADC for sample-and-hold and successive-approximation functions Another method performs a traditional initial successive-approximation analog-to-digital conversion, and then performs an additional conversion-step test based on the least-significant bit of the initial result to correct for comparator errors in the initial conversion

Charge-redistribution analog-to-digital converter with reduced comparator-hysteresis effects

An element of an integrated circuit, such as an ion implanted region or a metal layer, may be laser trimmed without exposing P-N junctions or other circuit elements not to be trimmed to damage by the laser through use of the present protection process and structure. In the process, an oxide through which the laser trimming is carried out is formed over a selected portion of the circuit to be trimmed by the laser. A bare layer of a metal reflective to the laser radiant energy beam, such as aluminum, gold or silver, is formed surrounding the selected portion of the circuit. The selected portion of the integrated circuit is then trimmed with the laser. The oxide promotes trimming in the selected area by absorbing the laser radiant energy beam. The bare metal layer protects the portion of the integrated circuit underlying it by reflecting most of its energy.

Laser trim protection process

Laser trim protection process and structure

An expanded analog-to-digital converter includes a first digital-to-analog converter for converting the most significant bits of digital output signal having a given number of bits to a first analog reference signal having a value that is proportional to the value of the most significant bits minus one-half the least significant bit of the digital output signal whenever the value of the most significant bits is other than zero; and a second digital-to-analog converter for converting the least significant bits of the digital output signal to a second analog reference signal. A successive approximation register successively provides the bits of a digital output signal in accordance with a comparison of an analog input signal with the sum of the analog reference signals. A logic circuit coupled to the successive approximation register for providing an indication of whether the value of the most significant bits is other than zero, causes the second analog reference signal to have a value that is proportional to the value of the least significant bits whenever the value of the most significant bits is other than zero, and a value that is proportional to the value of the least significant bits minus one-half the least significant bit of the digital output signal whenever the value of the most significant bits is zero.

Expanded analog-to-digital converter having one-half LSB shift

A base junction transistor inverter circuit will be driven into the saturation region if the drive current is large enough. In such circumstances, the collector voltage can go below the base voltage and approaches the emitter voltage. A circuit is provided to keep the transistor out of saturation and is comprised of a p-channel field effect transistor (JFET) connected between the base and collector of the junction transistor. The JFET is connected such that when the drive current increases and the junction transistor approaches saturation, the drive current is diverted through the JFET and into the substrate. The same clamp can be implemented by using a pnp junction transistor in combination with an n-channel JFET.

JFET base junction transistor clamp

An integrated circuit includes a plurality of circuit elements interconnected to operate as a circuit and formed in a common semiconductor substrate. The substrate is mounted on a supporting package, resulting in a mechanical stress in the substrate which is symmetrical about at least one given axis. At least the circuit elements with operating characteristics which are altered by the mechanical stress and which have a critical matching or ratio relationship are arranged symmetrically about the stress axis of symmetry. In a preferred form, the integrated circuit is a linear circuit, such as an operational amplifier employing junction field effect transistors (JFETs) for its input stage and bipolar transistors for its amplifier stage. Providing device symmetry about an axis of mechanical stress symmetry enables shifts in input offset voltage for such operational amplifiers to be reduced up to a factor of about 10.

Daniel D. Culmer

Papers

Laser trim protection process

Laser trim protection process and structure

Expanded analog-to-digital converter having one-half LSB shift

JFET base junction transistor clamp

Stress insensitive integrated circuit