The phase-shifting mask consists of a normal transmission mask that has been coated with a transparent layer patterned to ensure that the optical phases of nearest apertures are opposite. Destructive interference between waves from adjacent apertures cancels some diffraction effects and increases the spatial resolution with which such patterns can be projected. A simple theory predicts a near doubling of resolution for illumination with partial incoherence σ < 0.3, and substantial improvements in resolution for σ < 0.7. Initial results obtained with a phase-shifting mask patterned with typical device structures by electron-beam lithography and exposed using a Mann 4800 10× tool reveals a 40-percent increase in usuable resolution with some structures printed at a resolution of 1000 lines/mm. Phase-shifting mask structures can be used to facilitate proximity printing with larger gaps between mask and wafer. Theory indicates that the increase in resolution is accompanied by a minimal decrease in depth of focus. Thus the phase-shifting mask may be the most desirable device for enhancing optical lithography resolution in the VLSI/VHSIC era.

Improving resolution in photolithography with a phase-shifting mask

Process gas discharged from a bypass pipe to a gas exhaust system can be prevented from diffusing back to the inside of a process chamber without having to install a dedicated vacuum pump at the downstream side of the bypass pipe. The substrate processing apparatus includes a process chamber accommodating a substrate, a gas supply system supplying process gas from a process gas source to the process chamber for processing the substrate, a gas exhaust system configured to exhaust the process chamber, two or more vacuum pumps installed in series at the gas exhaust system, and a bypass pipe connected between the gas supply system and the gas exhaust system. The most upstream one of the vacuum pumps is a mechanical booster pump, and the bypass pipe is connected between the mechanical booster pump and the rest vacuum pumps located at a downstream side of the mechanical booster pump.

Substrate Processing Apparatus

Various methods and systems for utilizing design data in combination with inspection data are provided. One computer-implemented method for binning defects detected on a wafer includes comparing portions of design data proximate positions of the defects in design data space. The method also includes determining if the design data in the portions is at least similar based on results of the comparing step. In addition, the method includes binning the defects in groups such that the portions of the design data proximate the positions of the defects in each of the groups are at least similar. The method further includes storing results of the binning step in a storage medium.

Methods and systems for utilizing design data in combination with inspection data

Lithography is a field in which advances proceed at a swift pace. This book was written to address several needs, and the revisions for the second edition were made with those original objectives in mind. Many new topics have been included in this text commensurate with the progress that has taken place during the past few years, and several subjects are discussed in more detail. This book is intended to serve as an introduction to the science of microlithography for people who are unfamiliar with the subject. Topics directly related to the tools used to manufacture integrated circuits are addressed in depth, including such topics as overlay, the stages of exposure, tools, and light sources. This text also contains numerous references for students who want to investigate particular topics in more detail, and they provide the experienced lithographer with lists of references by topic as well. It is expected that the reader of this book will have a foundation in basic physics and chemistry. No topics will require knowledge of mathematics beyond elementary calculus.

Principles of Lithography

A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Lithographic apparatus, and device manufacturing method

A system and/or method are disclosed for measuring and/or controlling refractive index (n) and/or lithographic constant (k) of an immersion medium utilized in connection with immersion lithography. A known grating structure is built upon a substrate. A refractive index monitoring component facilitates measuring and/or controlling the immersion medium by utilizing detected light scattered from the known grating structure.

Refractive index system monitor and control for immersion lithography

An arrangement for optimizing a lithographic process forms a pattern on a silicon wafer using a photocluster cell system to simulate an actual processing condition for a semiconductor product. The resist pattern is then inspected using a wafer inspection system. An in-line low voltage scanning electron microscope (SEM) system reviews and classifies defect types, enabling generation of an alternative processing specification. The alternative processing specification can then be tested by forming patterns on different wafers, and then performing split-series testing to analyze the patterns on the different wafers for comparison with the existing lithographic process and qualification for production.

Apparatus and method for reducing defects in a semiconductor lithographic process

A method for new product mask evaluation is provided. Focus exposure matrices are printed at one or more layers (e.g., active gate) on full flow production wafers. The focus exposure matrices are then analyzed to produce data that facilitates detecting printed defects. The full flow production wafers are also subjected to end of line electrical testing to determine bit level errors. Print defects can be correlated with bit level errors to increase confidence in detected defects. The method includes a hierarchy of testing layers, each of which produce data that can be employed in detecting defects in a reticle and/or producing a yield analysis. The method involves scanning a reticle upon which the new product mask is etched and performing a printability simulation to determine what affect, if any, detected reticle defects will have on printing defects on a wafer. After the reticle is scanned, full flow production wafers printed from the pattern on the reticle can be scanned for defects, as can resist-on-silicon flat test wafers, where a higher signal to noise ratio facilitates detecting defects that may otherwise not be detected. The reticle scanning can include critical dimension measuring by scanning electron microscopy means and/or scatterometry means.

Full flow focus exposure matrix analysis and electrical testing for new product mask evaluation

A low cost technique for detecting defects in photolithography processes in a submicron integrated circuit manufacturing environment combines use of a reusable test wafer with in-line processing to monitor defects using a pattern comparator system. A reusable test wafer having an oxide layer overlying a silicon substrate and having a thickness corresponding to a minimum reflectance for an exposure wavelength used for photolithography is patterned using a prescribed photolithographic fabrication process to form a repetitive pattern according to a prescribed design product rule. The pattern is formed using a reticle having a repetitive pattern array with a similar design rule as the product to be developed by the lithography processes. The patterned test wafer is then inspected using image-based inspection techniques, where the image has high resolution pixels of preferably 0.25 microns per pixel. An optical review station and scanning electron microscope system are used to review defect and classify defect types. The test wafer can then be reused by cleaning the photolithographic pattern by removing the photoresist, and then removing polymer particles adhering to the oxide layer following removal of the photoresist.

Low cost application of oxide test wafer for defect monitor in photolithography process

A system and method are provided for detecting latent defects in a mask or reticle, which defects may vary as a function of radiation at exposure wavelengths. By way of example, the mask or reticle is inspected, exposed to radiation at a specified wavelength, and then reinspected. A correlation between the inspection results before and after exposure provides an indication of exposure-related defects, which may include defect growth and/or formation of defects caused by the exposure. By way of further illustration, the combination of inspection and exposure of a mask or reticle may be implemented with respect to a pellicized mask or reticle so as to detect additional defects related to use of the pellicle with the mask or reticle.

Khoi A. Phan

Papers

Refractive index system monitor and control for immersion lithography

Apparatus and method for reducing defects in a semiconductor lithographic process

Full flow focus exposure matrix analysis and electrical testing for new product mask evaluation

Low cost application of oxide test wafer for defect monitor in photolithography process

Defect detection in pellicized reticles via exposure at short wavelengths