摘要:
An optical system may include an objective having at least four mirrors including an outermost mirror with aspect ratio 0.7, central obscuration 0.7 and field of view >0.8 mm. An optical imaging system may comprise an objective and two or more imaging paths. The imaging paths may provide two or more simultaneous broadband images of a sample in two or more modes. The modes may have different illumination and/or collection pupil apertures or different pixel sizes at the sample.
摘要:
A dark field diffraction based overlay metrology device illuminates an overlay target that has at least three pads for an axis, the three pads having different programmed offsets. The overlay target may be illuminated using two obliquely incident beams of light from opposite azimuth angles or using normally incident light. Two dark field images of the overlay target are collected using ±1st diffraction orders to produce at least six independent signals. For example, the +1st diffraction order may be collected from one obliquely incident beam of light and the −1st diffraction order may be collected from the other obliquely incident beam of light. Alternatively, the ±1st diffraction orders may be separately detected from the normally incident light to produce the two dark field images of the overlay target. The six independent signals from the overlay target are used to determine an overlay error for the sample along the axis.
摘要:
An optical system may include an objective having at least four mirrors including an outermost mirror with aspect ratio 0.7, central obscuration 0.7 and field of view >0.8 mm. An optical imaging system may comprise an objective and two or more imaging paths. The imaging paths may provide two or more simultaneous broadband images of a sample in two or more modes. The modes may have different illumination and/or collection pupil apertures or different pixel sizes at the sample.
摘要:
Systems configured to provide illumination of a specimen during inspection are provided. One system includes catoptric elements configured to direct light from a light source to a line across the specimen at an oblique angle of incidence. The catoptric elements include positive and negative elements configured such that pupil distortions of the positive and negative elements are substantially canceled. Another system includes a dioptric element and a catoptric element. The dioptric element and the catoptric element are configured to direct light from a light source to a line across the specimen at an oblique angle of incidence. The dioptric and catoptric elements are also configured such that pupil distortions of the dioptric and catoptric elements are substantially canceled.
摘要:
A WDM demultiplexer/multiplexer comprising a plurality of narrow band reflective filters linearly disposed along an optical axis, each narrow band reflective filter reflecting a single channel or group of channels and transmitting the remaining channels, is described. In a demultiplexing mode, an optical signal initially carrying channels at &lgr;1&lgr;2 . . . &lgr;N travels along the optical axis. Each narrow band reflective filter reflects a distinct channel and is tilted with respect to the optical axis such that it directs the reflected beam away from the optical axis to an output. Each narrow band reflective filter is substantially transparent to the remaining channels of the optical signal, such that the remainder of the optical signal proceeds along the optical axis substantially undisturbed. Advantageously, the device is highly robust against tilt variations or other mechanical variations in the narrow band reflective filters, because such variations are not compounded as the optical signal travels through the device. When many channels “N” require multiplexing/demultiplexing, the incoming beam may be split into “m” separate beams and sent to “m” separate narrowband reflective filter arrays, each comprising about N/m narrowband reflective filters. An optimal number of beams “m” for best energy efficiency may be computed based on specified system parameters.
摘要:
An optical system to project an image from an illuminated object to an image plane with a selected magnification factor. This system includes a lens system having a fixed magnification factor and at least one flat plate that is optically compatible with the lens system and which when bent into a cylindrical shape varies the fixed magnification factor of the lens system along one axis of the image. This variable magnification technique is applicable to all lens system types, including a Wynne Dyson type projection system. In addition, a Wynne Dyson optical projection system that includes an optical block in place of the usual fold prism is discussed. The optical block reduces changes in distortion caused by heat transferred from the reticle. The block permits the inclusion of a dichroic beamsplitter diagonally through the optical block which presents minimal attenuation of the exposure illumination. The beamsplitter reflects a portion of the light returning from the image plane to a conjugate focal plane where alignment between the image and the pattern on the substrate can be viewed with a microscope. Illumination projected through the conjugate image plane permits the pattern on the substrate to be viewed directly without interference from the object pattern.
摘要:
An illumination system for use in a unit magnification optical projection system (such as a Half-Field Dyson system) is provided. In a Half-Field Dyson system, a reticle and a wafer are parallel to each other with a window being provided on the reticle to allow for projection of the reticle pattern onto the wafer. The present invention provides uniform bright illumination over the reticle pattern with little or no spill over through the reticle window.