Resistor trimming with small uniform spot from solid-state UV laser
First Claim
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1. A method of laser trimming a film resistor to change from an initial value to a nominal value a parameter of the resistor that includes a film resistor material supported on a substrate, the film resistor material contributing to a determination of the initial value of the parameter, the method comprising:
- producing a Gaussian beam of at least one laser pulse of UV radiation having an energy density spatial profile of generally Gaussian shape;
propagating the Gaussian beam along an optical path through a beam shaping element to convert the Gaussian beam into a transformed beam having a more substantially uniform energy density spatial profile;
propagating a major portion of the transformed beam through an aperture to convert it into a target beam that forms a target spot with a substantially uniform energy density spatial profile;
directing the target beam onto a target area of the film resistor material to ablate the film resistor material within the target area of the resistor to change its initial value to the nominal value and penetrating the substrate to form a kerf through the film resistor material and uniformly expose a major portion of the substrate within the target area, the substantially uniform energy density spatial profile of the target spot having an effective energy density value that minimizes formations of microcracks in the substrate.
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Abstract
A uniform laser spot, such as from an imaged shaped Gaussian output (118) or a clipped Gaussian spot, that is less than 20 μm in diameter can be employed for both thin and thick film resistor trimming to substantially reduce microcracking. These spots can be generated in an ablative, nonthermal, UV laser wavelength to reduce the HAZ and/or shift in TCR.
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Citations
50 Claims
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1. A method of laser trimming a film resistor to change from an initial value to a nominal value a parameter of the resistor that includes a film resistor material supported on a substrate, the film resistor material contributing to a determination of the initial value of the parameter, the method comprising:
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producing a Gaussian beam of at least one laser pulse of UV radiation having an energy density spatial profile of generally Gaussian shape;
propagating the Gaussian beam along an optical path through a beam shaping element to convert the Gaussian beam into a transformed beam having a more substantially uniform energy density spatial profile;
propagating a major portion of the transformed beam through an aperture to convert it into a target beam that forms a target spot with a substantially uniform energy density spatial profile;
directing the target beam onto a target area of the film resistor material to ablate the film resistor material within the target area of the resistor to change its initial value to the nominal value and penetrating the substrate to form a kerf through the film resistor material and uniformly expose a major portion of the substrate within the target area, the substantially uniform energy density spatial profile of the target spot having an effective energy density value that minimizes formations of microcracks in the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
generating the Gaussian beam from a Q-switched, diode-pumped, solid-state laser.
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17. The method of claim 1 in which the Gaussian beam shaping element comprises a diffractive optical element.
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18. The method of claim 1 in which the Gaussian beam comprises a wavelength of about 355 nm, 349 nm, 266 nm, or 262 nm.
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19. The method of claim 1 in which the Gaussian beam has an energy and the target beam has an apertured shaped energy that is greater than 50% of the energy of the Gaussian beam.
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20. The method of claim 1 in which the aperture has a square shape.
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21. A method of changing from an initial value to a nominal value with longterm stability a parameter of a microelectronic circuit component that includes a region of film material supported on a substrate, the region defining a volumetric space that contributes to a determination of the initial value of the parameter, the method comprising:
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producing a laser beam having an energy density spatial profile of generally Gaussian shape;
converting the laser beam having a Gaussian energy density spatial profile into a target beam that forms a target spot with a substantially uniform energy density spatial profile; and
directing the target beam onto the region of film material to ablate a quantity of the film material to change its initial value to the nominal value, the substantially uniform energy density spatial profile of the target spot having an effective energy density value that minimizes in the substrate or the film material formations of microcracks of sizes and depths that cause spurious break line formations in the substrate. - View Dependent Claims (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)
generating Gaussian beam from a Q-switched, diode-pumped, solid-state laser.
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34. The method of claim 21 in which converting the Gaussian beam to the target beam includes passing the beam through an aperture mask for clipping a peripheral portion of the Gaussian beam.
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35. The method of claim 34 in which converting the laser beam to a target beam includes passing the laser beam through a beam shaping element, positioned up stream of the aperture mask, for shaping the laser beam.
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36. The method of claim 35 in which the beam shaping element comprises a diffractive optical element.
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37. The method of claim 36 in which converting the laser beam to a target beam includes passing the beam through a focusing element, positioned up stream of the aperture mask, for shaping the laser beam.
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38. The method of claim 21 in which the substantially uniform energy density spatial profile of the target spot has an effective energy density value that minimizes in the substrate or the film material formation of microcracks of sizes and depths that cause parameter value drift from the nominal value.
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39. The method of claim 21 in which the microelectronic component comprises a 0402 or 0201 chip resistor.
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40. The method of claim 21 in which the substrate is penetrated to a depth of less than 10 μ
- m.
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41. The method of claim 40 further comprising:
forming a kerf having a uniformly exposed substrate at the bottom of the kerf.
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42. The method of claim 21 in which the substrate is penetrated to a depth of at least 0.1 μ
- m.
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43. The method of claim 21 in which the substrate is penetrated to a depth of less than 5 μ
- m.
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44. The method of claim 21 in which converting the laser beam to a target beam includes passing the laser beam through a beam shaping element.
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45. The method of claim 21 in which laser beam comprises a UV wavelength.
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46. The method of claim 35 in which the laser beam comprises an IR wavelength.
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47. The method of claim 46 in which target spot comprises a wavelength of about 1.32 and the substrate comprises silicon.
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48. The method of claim 21 in which only a top quantity of the volumetric space of the film material is ablated such that the substrate remains unexposed.
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49. The method of claim 35 in which the laser beam comprises visible wavelength.
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50. The method of claim 21 in which the microelectronic component comprises a capacitor or an inductor.
Specification
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Current AssigneeElectro Scientific Industries Incorporated (MKS Instruments Incorporated)
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Original AssigneeElectro Scientific Industries Incorporated (MKS Instruments Incorporated)
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InventorsSun, Yunlong, Harris, Richard S., Swenson, Edward J.
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Primary Examiner(s)ELVE, MARIA ALEXANDRA
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Application NumberUS10/066,351Publication NumberTime in Patent Office411 DaysField of Search219/121.69, 219/121.6, 219/121.68, 219/121.83US Class Current219/121.69CPC Class CodesB23K 26/073 Shaping the laser spotH01C 17/242 by laser trimming by laser ...
