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US 2003/0151053 A1Published application
Processing a memory link with a set of at least two laser pulses
AssigneeElectro Scientific Industries, Inc.
InventorsYunlong Sun, Edward J. Swenson, Richard S. Harris
Life of this patent
Estimating the term…
Abstract
A set (50) of laser pulses (52) is employed to sever a conductive link (22) in a memory or other IC chip. The duration of the set (50) is preferably shorter than 1,000 ns; and the pulse width of each laser pulse (52) within the set (50) is preferably within a range of about 0.1 ps to 30 ns. The set (50) can be treated as a single “pulse” by conventional laser positioning systems (62) to perform on-the-fly link removal without stopping whenever the laser system (60) fires a set (50) of laser pulses (52) at each link (22). Conventional IR wavelengths or their harmonics can be employed.
Claims75
A method of selectively severing electrically conductive redundant memory or integrated circuit links having associated link structures, each link having a link width and being positioned between an associated pair of electrically conductive contacts in a circuit fabricated on a substrate, the substrate and an optional underlying passivation layer between the electrically conductive link and the substrate as associated with the link structures being characterized by energy damage thresholds and a peak power damage thresholds, comprising:
- providing to a beam positioner beam positioning data representing one or more locations of the selected electrically conductive links, the beam positioner in response to the beam positioning data imparting relative movement of a laser spot position to the substrate;
- generating for each selected link structure a set of two or more time-displaced laser output pulses, each of the laser output pulses in the set characterized by a laser spot having a spot size, an energy, and peak power at the laser spot position, the spot size being larger than the link width and the energy and peak power being less than the respective damage thresholds of any underlying passivation layer and the substrate;
- and
- coordinating laser output pulse generation and the relative movement imparted by the beam positioner such that the relative movement is substantially continuous while the laser output pulses in the set sequentially strike the selected link structure so that the spot of each laser output pulse in the set encompasses the link width and the set severs the electrically conductive link between its associated pair of electrically conductive contacts without causing damage to any underlying passivation layer and the substrate.
1 more element
A method of severing electrically conductive redundant memory or integrated circuit links positioned between respective pairs of electrically conductive contacts in a circuit fabricated on a substrate, each link having a link width, comprising:
- providing to a beam positioner beam positioning data representing one or more locations of electrically conductive links in the circuit, the beam positioner coordinating relative movement between a laser spot position and the substrate;
- generating, from a first laser, at least one first laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during a first time interval that is shorter than about 1,000 nanoseconds, the first laser output pulse also having a first laser spot with a spot size that is greater than the link width;
- directing, in accordance with the beam positioning data, the first laser output pulse so that the first laser spot impinges a first location of a first electrically conductive link between first contacts;
- generating, from a second laser, at least one second laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during the first time interval, the second laser output pulse also having a second laser spot with a spot size that is greater than the link width;
- directing, in accordance with the beam positioning data, the second laser output pulse so that the second laser spot impinges the first location of the first electrically conductive link such that the first and second laser spots substantially overlap and the first and second laser output pulses contribute to the removal of the first electrically conductive link;
- generating, from the first laser, at least one third laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during a second time interval that is shorter than 1,000 nanoseconds and time-displaced from the first time interval, the third laser output pulse also having a third laser spot with a spot size that is greater than the link width;
- directing, in accordance with the beam positioning data, the third laser output pulse so that the third laser spot impinges a second location of a second electrically conductive link between second contacts that is distinct from the first location;
- generating, from the second laser, at least one fourth laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during the second time interval, the fourth laser output pulse also having a fourth laser spot with a spot size that is greater than the link width;
- and
- directing, in accordance with the beam positioning data, the fourth laser output pulse to impinge the second location of the second electrically conductive link such that the third and fourth laser spots substantially overlap and the third and fourth laser output pulses contribute to the removal of the second electrically conductive link.
7 more elements
A method of severing electrically conductive redundant memory or integrated circuit links positioned between respective pairs of electrically conductive contacts in a circuit fabricated on a substrate, each link having a link width, comprising:
- providing to a beam positioner beam positioning data representing one or more locations of electrically conductive links in the circuit, the beam positioner coordinating relative movement between a laser spot position and the substrate;
- generating from a laser at least one first laser pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during a first time interval that is shorter than 1,000 nanoseconds;
- propagating the first laser pulse along a first optical path;
- splitting the first laser pulse into first and second laser output pulses such that the first laser output pulse propagates along the first optical path and such that the second laser output pulse propagates along a second optical path, the first and second laser output pulses also having respective first and second laser spots having spot sizes that are greater than the link width;
- directing, in accordance with the beam positioning data, the first laser output pulse so that the first laser spot impinges a first location of a first electrically conductive link between first contacts during the first time interval;
- directing the second laser output pulse so that the second laser spot impinges the first location of the first electrically conductive link during the first time interval such that the first and second laser spots substantially overlap and the first and second laser output pulses contribute to the removal of the first conductive link, the second optical path having a characteristic that causes the second laser pulse to reach the first electrically conductive link after the first laser pulse reaches the first electrically conductive link;
- generating from the laser at least one second laser pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during a second time interval that is shorter than 1,000 nanoseconds;
- propagating the second laser pulse along the first optical path;
- splitting the second laser pulse into third and fourth laser output pulses such that the third laser output pulse propagates along the first optical path and such that the fourth laser output pulse propagates along the second optical path, the third and fourth laser output pulses also having respective third and fourth laser spots having spot sizes that are greater than the link width;
- directing, in accordance with the beam positioning data, the third laser output pulse so that the third laser spot impinges a second location of a second electrically conductive link between second contacts during the second time interval;
- and
- directing the fourth laser output pulse so that the fourth laser spot impinges the second location of the second electrically conductive link during the second time interval such that the third and fourth laser spots substantially overlap and the third and fourth laser output pulses contribute to the removal of the second electrically conductive link, the second optical path having a characteristic that causes the fourth laser pulse to reach the second conductive link after the third laser pulse reaches the second electrically conductive link.
9 more elements
A method of severing electrically conductive redundant memory or integrated circuit links positioned between respective pairs of electrically conductive contacts in a circuit fabricated on a substrate, each link having a link width, comprising:
- providing to a beam positioner beam positioning data representing one or more locations of electrically conductive links in the circuit, the beam positioner coordinating relative movement between a laser spot position and the substrate;
- reducing an RF signal to a Q-switch from a high RF level to an intermediate RF level to generate from a laser at least one first laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during a first time interval that is shorter than 1,000 nanoseconds, the first laser output pulse also having a first laser spot with a spot size that is greater than the link width;
- directing, in accordance with the beam positioning data, the first laser output pulse so that the first laser spot impinges a first location of a first electrically conductive link between first contacts;
- reducing the RF signal to the Q-switch from the intermediate RF level to a smaller RF level to generate at least one second laser output pulse having a pulse width of between about 25 picoseconds and 30 nanoseconds during the first time interval, the second laser output pulse also having a second laser spot with a spot size that is greater than the link width;
- directing the second laser output pulse so that the second laser spot impinges the first location of the first electrically conductive link such that the first and second laser spots substantially overlap and the first and second laser output pulses contribute to the removal of the first electrically conductive link;
- increasing the RF signal to the Q-switch from the smaller RF level to the high RF level;
- reducing the RF signal to the Q-switch from the high RF level to the intermediate RF level to generate from the laser at least one third laser output pulse having a pulse width duration of between about 25 picoseconds and 30 nanoseconds during a second time interval having a set width duration of shorter than 1,000 nanoseconds, the third laser output pulse also having a third laser spot with a spot size that is greater than the link width;
- directing, in accordance with the beam positioning data, the third laser output pulse so that the third laser spot impinges a second location of a second electrically conductive link between second contacts;
- reducing the RF signal to the Q-switch from the intermediate RF level to the smaller RF level to generate at least one fourth laser output pulse having a pulse width duration of between about 25 picoseconds and 30 nanoseconds during the second time interval, the fourth laser output pulse also having a fourth laser spot with a spot size that is greater than the link width;
- and
- directing the fourth laser output pulse so that the fourth laser spot impinges the second location of the second electrically conductive link such that the third and fourth laser spots substantially overlap and the third and fourth laser output pulses contribute to the removal of the second electrically conductive link.
8 more elements
A laser system for employing laser output to sever electrically conductive redundant memory or integrated circuit links of associated link structures, each link having a link width and being positioned between an associated pair of electrically conductive contacts in a circuit fabricated on a substrate, the substrate associated with the link structures being characterized by an energy damage threshold and a peak power damage threshold, comprising:
- a pumping source for providing pumping light;
- a laser resonator adapted to receive the pumping light and emit laser output pulses each having a pulse width that is shorter than 25 picoseconds;
- a mode locking device for mode locking the laser resonator;
- a burst gating device to separate laser output pulses into discrete bursts of laser output such that each burst includes at least two time-displaced laser output pulses and has a burst width that is shorter than 1,000 nanoseconds, each of the laser output pulses in the burst characterized by a laser spot having a spot size, an energy, and peak power at a laser spot position, the spot size being larger than the link width and the energy and peak power being less than the respective damage thresholds of the substrate;
- a beam positioning system for imparting relative movement of the laser spot position to the substrate in response to beam positioning data representing one or more locations of selected electrically conductive links;
- and
- a laser system controller for coordinating operation of the burst gating device and the relative movement imparted by the beam positioner such that the relative movement is substantially continuous while the laser output pulses in the burst sequentially strike the selected link structure so that the spot of each laser output pulse in the burst encompasses the link width and the burst severs the electrically conductive link between its associated pair of electrically conductive contacts without causing damage to the substrate.
4 more elements
Dependencies are inferred from the claim text.