Abstract: The present invention generally relates to optical lithography and more particularly relates to the fabrication of transparent or semitransparent phase shifting masks used in the manufacture of semiconductor devices. In particular, the present invention utilizes a light absorbing film in a conventional aaPSMs to balance the intensity of light through each opening of the photomask. The aaPSM of the present invention is used to make semiconductor devices or integrated circuits.

Abstract: A reticle has a transparent substrate, mask shapes on the substrate, a transparent material covering the mask shapes and an optional anti-reflective material over the transparent material.

Abstract: A method of modeling dose and focus response in lithographic imaging to simulate an optical critical dimension (OCD) metrology system creates simulated aerial images of the object pattern to be transferred to a resist film on the substrate at different focus settings of the metrology imaging system. The method then successively creates simulated images, at different exposure dose and focus settings of the metrology imaging system, of the latent and developed image of the object pattern in the resist film on the substrate, and the etched image of the object pattern in the substrate. The method converts the simulated images into polygons having more than four sides and determines the Fourier spectrum of the polygons simulating the images of the object pattern.

Abstract: The present invention generally relates to improved binary half tone (“BHT”) photomasks and microscopic three-dimensional structures (e.g., MEMS, micro-optics, photonics, micro-structures and other three-dimensional, microscopic devices) made from such BHT photomasks. More particularly, the present invention provides a method for designing a BHT photomask layout, transferring the layout to a BHT photomask and fabricating three-dimensional microscopic structures using the BHT photomask designed by the method of the present invention. In this regard, the method of designing a BHT photomask layout comprises the steps of generating at least two pixels, dividing each of the pixels into sub-pixels having a variable length in a first axis and fixed length in a second axis, and arraying the pixels to form a pattern for transmitting light through the pixels so as to form a continuous tone, aerial light image.

Abstract: The present invention generally relates to optical lithography and more particularly relates to the fabrication of transparent or semitransparent phase shifting masks used in the manufacture of semiconductor devices. In particular, the present invention utilizes a light absorbing film in a conventional aaPSMs to balance the intensity of light through each opening of the photomask. The aaPSM of the present invention is used to make semiconductor devices or integrated circuits.

Abstract: A method for inspecting masks used to project patterns in photolithographic imaging comprises initially providing a photolithographic mask having a pattern field thereon, where in normal production use the pattern is transferred by a reduction projector as a demagnified pattern on a production substrate, and providing a movable field-defining aperture adjacent the mask, the aperture having a field area less than, and capable of defining a pattern subfield comprising only a portion of the entire photolithographic mask pattern field. The method then includes aligning the field-defining aperture with a pattern subfield comprising only a portion of the entire photolithographic mask pattern field. Using an energy source, the method includes projecting the pattern subfield onto a test substrate and exposing onto the test substrate the pattern subfield at a size between that normally exposed on a production substrate and the actual size of the pattern subfield on the photolithographic mask.

Abstract: A reticle has a transparent substrate, mask shapes on the substrate, a transparent material covering the mask shapes and an optional anti-reflective material over the transparent material.

Abstract: The present invention generally relates to improved binary half tone (“BHT”) photomasks and microscopic three-dimensional structures (e.g., MEMS, micro-optics, photonics, micro-structures and other three-dimensional, microscopic devices) made from such BHT photomasks. More particularly, the present invention provides a method for designing a BHT photomask layout, transferring the layout to a BHT photomask and fabricating three-dimensional microscopic structures using the BHT photomask designed by the method of the present invention. In this regard, the method of designing a BHT photomask layout comprises the steps of generating at least two pixels, dividing each of the pixels into sub-pixels having a variable length in a first axis and fixed length in a second axis, and arraying the pixels to form a pattern for transmitting light through the pixels so as to form a continuous tone, aerial light image.

Abstract: A method for optically measuring lithographic process bias of a minimum feature formed by a lithographic process. The method comprises creating on a substrate an array of elements from which a darkfield optical image is generated and detected, electronic information corresponding to the image is generated and processed, and the difference between the created length versus the nominal length of the elements is calculated to determine lithographic process bias. The darkfield optical image may be a double-lobe optical image, and signal processing may comprise creating a normalized intensity profile to overcome film-thickness dependencies, to which one or more noise-rejecting, edge-detection methods is or are applied to calculate the created length of the elements. A method for using double-lobe darkfield imaging for general edge detection is also disclosed.

Abstract: A scanning method capable of reducing across chip linewidth variation and image placement error is disclosed, the method including a step whereby a reticle having a plurality of lines is scanned in a direction perpendicular to the lines. The scanning method includes a radiation source provided with an aperture with a slot. In this case, it is preferable that the radiation source keeps the rectangular slot in the direction that minimizes pattern distortions.

Abstract: A method for optically measuring lithographic process bias of a minimum feature formed by a lithographic process. The method comprises creating on a substrate an array of elements from which a darkfield optical image is generated and detected, electronic information corresponding to the image is generated and processed, and the difference between the created length versus the nominal length of the elements is calculated to determine lithographic process bias. The darkfield optical image may be a double-lobe optical image, and signal processing may comprise creating a normalized intensity profile to overcome film-thickness dependencies, to which one or more noise-rejecting, edge-detection methods is or are applied to calculate the created length of the elements. A method for using double-lobe darkfield imaging for general edge detection is also disclosed.

Abstract: A test photomask comprising a fresnel zone target (FZT) pattern may be used to verify the adjustment of a precision projector illumination system of an image projection system. The method comprises the steps of creating the FZT pattern on a photomask, projecting a pupil diagram onto an image plane using the FZT pattern, and evaluating the pupil diagram to determine the illumination system adjustment.

Abstract: Optical measurement of image shortening on a lithographically formed minimum feature is enhanced using crossed-polarizer imaging. The minimum feature, which is comprised of a nested array of lines having a width and space corresponding to the critical dimension of interest, is caused to maintain a preferred optical polarization axis due to the repeating nature of the nested pattern. The preferred optical polarization axis causes the transfer of some of the linearly polarized illumination into a new polarization orientation which is sympathetic with a crossed polarizer located in the detection channel of the optical imaging system. The crossed polarizer then allows the light reflected from the nested feature to pass to a detector, while extraneous (background) light is rejected. This results in a high contrast image of the nested feature that facilitates the determination of width, and that reduces measurement variability as a function of the optical properties of the nested feature.

Abstract: In a reverse darkfield (RDF) microlithography alignment system a confocal spatial filtering system discriminates against topographical features other than the alignment mark. A CCD detector array provides flexible confocal filtering via a pixel weighting matched to the optical system. The confocal filtering system employs empirical filter optimization accomplished by correlating stored images with resulting overlays. The empirical optimization of the filter reweights the CCD array and correlates back to measured overlay results. This not only enhances the proven process insensitivity of RDF systems, but combines it with the improved resolution and noise rejection of confocal imaging. Alternatively the means for confocal spatial filtering is comprised of a filter matched to the instantaneous image of an alignment target; for example, a double slit filter matched to the image of a single alignment mark edge.

Abstract: Alignment of two objects such as a mask and a wafer is achieved using crossed polarizer imaging and polarization sensitive targets to enhance signal contrast in proximity alignment. Two linearly polarized illumination beams with electric field polarization axes at oblique angles to each other illuminate and interact with mask and wafer marks. The marks are oriented to induce a partial depolarization of each incident illumination at each plane, i.e. the marks make some of the light visible upon passing through filters and a polarization analyzer. When marks are viewed through a polarization analyzer stray light is rejected and mark contrast greatly improved.