Method and apparatus for laser trimming of resistors using ultrafast laser pulse from ultrafast laser oscillator operating in picosecond and femtosecond pulse widths
First Claim
1. A laser maching method for trimming a resistor film from an intial value to a desired value using ultrafast laser pulse from ultrafast laser oscillator comprising the step of;
- placing a resistor film on a substrate;
emitting a pulsed laser beam from ultrafast laser oscillator;
modulating the laser pulse, in order to minimize the cumulative heating effect and improve the machining quality;
expanding or reducing the beam to vary the diameter of the laser beam in one or two axis and hence the diameter of the focused spot size;
converting the polarization of the laser beam;
improving beam quality;
scanning the laser beam in two axes; and
focusinng the pulsed laser beam on to the resistor film on the substrate;
wherein the resistor film material is ablated within the target area of the resistor to change its initial value to the desired value.
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Accused Products
Abstract
The present invention relates to a method and apparatus for laser trimming of resistors in semiconductor applications using ultrafast laser pulse from diode pumped or CW pumped solid state mode locked ultrafast pulse laser oscillator without amplification. The invention disclosed has a means to avoid/reduce the cumulative heating effect to avoid machine quality degrading in multi shot ablation. The disclosed invention provides a cost effective and stable system for high volume manufacturing application. The disclosed invention is used for thick and thin film trimming. Ultrafast laser oscillator can be a called as femtosecond laser oscillator or a picosecond laser oscillator depending on the pulse with of the laser beam generated.
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Citations
68 Claims
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1. A laser maching method for trimming a resistor film from an intial value to a desired value using ultrafast laser pulse from ultrafast laser oscillator comprising the step of;
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placing a resistor film on a substrate;
emitting a pulsed laser beam from ultrafast laser oscillator;
modulating the laser pulse, in order to minimize the cumulative heating effect and improve the machining quality;
expanding or reducing the beam to vary the diameter of the laser beam in one or two axis and hence the diameter of the focused spot size;
converting the polarization of the laser beam;
improving beam quality;
scanning the laser beam in two axes; and
focusinng the pulsed laser beam on to the resistor film on the substrate;
wherein the resistor film material is ablated within the target area of the resistor to change its initial value to the desired value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A laser maching apparatus for trimming a resistor film from an intial value to a desired value using ultrafast laser pulse from ultrafast laser oscillator comprising the step of;
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a resistor film on a substrate;
a laser source that emits a pulsed laser beam from ultrafast laser oscillator;
modulating means for controlling the laser pulse, minimize the cumulative heating effect and improve the machining quality;
bam expanding or reducing means for varying the diameter of the laser beam in one or two axis and hence the diameter of the focused spot size;
means for polarization conversion;
means for improving beam quality;
scanning means for scanning the laser beam in two axes; and
focusing means for focusing the pulsed laser beam on to the resistor film on the substrate;
wherein the resistor film material is ablated within the target area of the resistor to change its initial value to the desired value. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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52. An apparatus for ablating a feature smaller then the focused spot size of the pulsed laser beam from an ultrfast laser oscillator of a pulse repetition rate of 1 MHZ to 400 MHZ, comprising;
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means for controlling the laser threshold fluence slightly above the ablation threshold of the material;
means for controlling the number of pulses and the duration between the pulses for minimizing or eliminating the cumulative heating effect, using pulse modulation means; and
wherein a spatial machining resolution of less than one-twentieth of a cross-sectional diameter of the pulsed laser beam in a focused state at the surface of the work piece is obtained.
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Specification