摘要:
An inspection apparatus measures a property of a substrate including a periodic structure. An illumination system provides a beam of radiation with an illumination profile including a plurality of illuminated portions. A radiation projector projects the beam of radiation onto the substrate. A detector detects radiation scattered from the periodic structure and separately detects first order diffracted radiation and at least one higher order of diffracted radiation of each of the illuminated portions. A processor determines the property of the substrate from the detected radiation. The plurality of illuminated portions are arranged such that first order diffracted radiation arising from one or more of the illuminated portions are not overlapped by zeroth order or first order diffracted radiation arising from any other of the illuminated portions. Furthermore, the plurality of illuminated portions are arranged such that first order diffracted radiation arising from the one or more of the illuminated portions are overlapped by at least one of the higher orders of diffracted radiation arising from any other of the illuminated portions.
摘要:
An inspection apparatus measures a property of a substrate including a periodic structure. An illumination system provides a beam of radiation with an illumination profile including a plurality of illuminated portions. A radiation projector projects the beam of radiation onto the substrate. A detector detects radiation scattered from the periodic structure and separately detects first order diffracted radiation and at least one higher order of diffracted radiation of each of the illuminated portions. A processor determines the property of the substrate from the detected radiation. The plurality of illuminated portions are arranged such that first order diffracted radiation arising from one or more of the illuminated portions are not overlapped by zeroth order or first order diffracted radiation arising from any other of the illuminated portions. Furthermore, the plurality of illuminated portions are arranged such that first order diffracted radiation arising from the one or more of the illuminated portions are overlapped by at least one of the higher orders of diffracted radiation arising from any other of the illuminated portions.
摘要:
A method of determining an overlay error. Measuring an overlay target having process-induced asymmetry. Constructing a model of the target. Modifying the model, e.g., by moving one of the structures to compensate for the asymmetry. Calculating an asymmetry-induced overlay error using the modified model. Determining an overlay error in a production target by subtracting the asymmetry-induced overlay error from a measured overlay error. In one example, the model is modified by varying asymmetry p(n′), p(n″) and the calculating an asymmetry-induced overlay error is repeated for a plurality of scatterometer measurement recipes and the step of determining an overlay error in a production target uses the calculated asymmetry-induced overlay errors to select an optimum scatterometer measurement recipe used to measure the production target.
摘要:
A method of determining an overlay error. Measuring an overlay target having process-induced asymmetry. Constructing a model of the target. Modifying the model, e.g., by moving one of the structures to compensate for the asymmetry. Calculating an asymmetry-induced overlay error using the modified model. Determining an overlay error in a production target by subtracting the asymmetry-induced overlay error from a measured overlay error. In one example, the model is modified by varying asymmetry p(n′), p(n″) and the calculating an asymmetry-induced overlay error is repeated for a plurality of scatterometer measurement recipes and the step of determining an overlay error in a production target uses the calculated asymmetry-induced overlay errors to select an optimum scatterometer measurement recipe used to measure the production target.
摘要:
An inspection system is arranged to measure an overlay error by projecting a plurality of radiation beams, differing in wavelength and/or polarization, onto two targets. A first radiation beam is projected onto a first target and the reflected radiation A1+ is detected. The first target comprises two gratings having a bias +d with respect to each other. The first radiation beam is also projected on to a second target, which comprises two gratings having a bias −d with respect to each other, and the reflected radiation A1− is detected. A second radiation beam, having a different wavelength and/or polarization from the first radiation beam, is projected onto the first target and reflected radiation A2+ is detected and projected onto the second target and reflected radiation A2− is detected. Detected radiations A1+, A1−, A2+, and A2− is used to determine the overlay error.
摘要:
An alignment sensor includes a spatially coherent radiation source that supplies a radiation beam to an angle-resolved scatterometer. Alignment is performed by detecting beats in the scatter spectrum during scanning of the substrate relative to the scatterometer.
摘要:
An overlay marker for use with a scatterometer includes two overlying two-dimensional gratings. The two gratings have the same pitch but the upper grating has a lower duty ratio. Cross-talk between X and Y overlay measurements can therefore be avoided. The gratings may be directly overlying or off set so as to be interleaved in one or two directions.
摘要:
According to an example, a first layer of a substrate comprises a plurality of gratings having a periodicity P. A second layer of the substrate comprises a plurality of gratings, overlapping with the first set of gratings, and having a periodicity of NP, where N is an integer greater than 2. A first set of gratings has a bias of +d and the second set of gratings has a bias of −d. A beam of radiation is projected onto the gratings and the angle resolved spectrum of the reflected radiation detected. The overlay error is then calculated using the angle resolved spectrum of the reflected radiation.
摘要:
An overlay marker for use with a scatterometer includes two overlying two-dimensional gratings. The two gratings have the same pitch but the upper grating has a lower duty ratio. Cross-talk between X and Y overlay measurements can therefore be avoided. The gratings may be directly overlying or off set so as to be interleaved in one or two directions.
摘要:
Both the 1st and 0th diffraction orders are detected in a scatterometer. The 1st diffraction orders are used to detect the overlay error. The 0th diffraction order is then used to flag if this is a false overlay error calculation of magnitude greater than the bias but smaller than the pitch of the grating.