Apparatus and method for measuring a property of a layer in a multilayered structure
First Claim
1. A method for determining a property of a portion of a structure having a first layer and at least one underlying layer in contact with the first layer, the method comprising:
- heating a region of the first layer using power modulated at a frequency that is predetermined to be sufficiently low to ensure that temperature of said region varies substantially linearly relative to said modulated power;
wherein the first layer comprises at least one crystalline phase from among a plurality of crystalline phases of a compound of a material comprised in said underlying layer, said crystalline phase depending on at least one process condition used in forming the first layer by annealing; and
wherein the first layer partially absorbs and partially transmits the power;
measuring a signal indicative of a change in reflectivity of said first layer due to a corresponding temperature change in the first layer caused by said heating;
using said measured signal to determine an electrical conductive property of said first layer, said electrical conductive property depending on crystalline phase.
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Accused Products
Abstract
An apparatus measures a property of a layer (such as the sheet resistance of a conductive layer) by performing the following method: (1) focusing the heating beam on the heated a region (also called “heated region”) of the conductive layer (2) modulating the power of the heating beam at a predetermined frequency that is selected to be sufficiently low to ensure that at any time the temperature of the optically absorbing layer is approximately equal to (e.g., within 90% of) a temperature of the optically absorbing layer when heated by an unmodulated beam, and (3) measuring the power of another beam that is (a) reflected by the heated region, and (b) modulated in phase with modulation of the heating beam. The measurement in act (3) can be used directly as a measure of the resistance (per unit area) of a conductive pad formed by patterning the conductive layer. Acts (1)-(3) can be repeated during fabrication of a semiconductor wafer, at each of a number of regions on a conductive layer, and any change in measurement indicates a corresponding change in resistance of the layer. When the measurement changes by more than a predetermined amount (e.g., by 10%), a process parameter that controls the fabrication process is changed to return the measurement to normal in the next wafer.
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Citations
34 Claims
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1. A method for determining a property of a portion of a structure having a first layer and at least one underlying layer in contact with the first layer, the method comprising:
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heating a region of the first layer using power modulated at a frequency that is predetermined to be sufficiently low to ensure that temperature of said region varies substantially linearly relative to said modulated power;
wherein the first layer comprises at least one crystalline phase from among a plurality of crystalline phases of a compound of a material comprised in said underlying layer, said crystalline phase depending on at least one process condition used in forming the first layer by annealing; and
wherein the first layer partially absorbs and partially transmits the power;
measuring a signal indicative of a change in reflectivity of said first layer due to a corresponding temperature change in the first layer caused by said heating;
using said measured signal to determine an electrical conductive property of said first layer, said electrical conductive property depending on crystalline phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An apparatus for evaluating an annealed structure, said annealed structure comprising a partially transmissive electrically conductive layer, said layer comprising at least one suicide among a plurality of silicides, said apparatus having a first line to be coupled to an annealing apparatus and a second line to be coupled to a metal formation apparatus, said apparatus comprising:
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a first source of a first beam of photons having a first power modulated at a frequency sufficiently low to ensure transfer of a majority of heat from a region of said layer illuminated by said first beam by diffusion;
a second source of a second beam of photons having a second power sufficiently low to ensure that an instantaneous temperature in said region is approximately equal to another temperature obtained in said region by heating with an unmodulated beam having power of an instantaneous value of said first power; and
a photosensitive element located in a path of a portion of said second beam after reflection from said region, said portion being modulated at said frequency of modulation of said first beam; and
a computer coupled to said photosensitive element and programmed to determine if power of said portion of said second beam reflected by said region is at least greater than a predetermined power and if so the computer driving a signal active on the first line to the annealing apparatus or on the second line to the metal formation apparatus or both.
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26. A method for evaluating a wafer, the method comprising:
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focusing a beam on a partially transmissive electrically conductive layer in said wafer, the partially transmissive electrically conductive layer comprising at least one silicide among a plurality of silicides, whose roughness is a function of crystal phase, and wherein said one silicide is formed by annealing;
measuring reflectance of said beam from said layer; and
correlating said reflectance from said layer to a previously determined value said previously determined value having been obtained from a previous reflectance measurement on a reference wafer. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34)
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Specification