John R. McNeil's research while affiliated with University of New Mexico and other places

Publications (62)

Article
In the work reported here, we discuss the measurement precision of two scatterometry techniques, the variable angle and the variable wavelength techniques. The issue of interest is the measurement precision of the sample parameters. This is determined by both the sensitivity of the diffraction measurable to changes in sample parameters and the prec...
Article
Phase-modulation scatterometry is a metrology technique for determining the parameters of gratings using as a key device a phase modulator. For measurement purposes the phase modulator requires a complicated calibration procedure that is analyzed here in detail. The main source of error to be dealt with are the fluctuations of the phase modulation...
Article
Full-text available
In the work reported here, we discuss the measurement precision of two scatterometry techniques, the variable angle and the variable wavelength techniques. The issue of interest is the measurement precision of the sample parameters. This is determined by both the sensitivity of the diffraction measurable to changes in sample parameters and the prec...
Article
Zero-order diffraction efficiencies, in reflection, of short-pitch (pitch less than the incident wavelength), narrow-linewidth, photoresist gratings exhibit significant variations with angle of incidence. The intent of our effort was to explain these variations, which are characterized as resonance anomalies. At resonance we also have observed enha...
Article
The sensitivity analysis of fitting (SAF) is a formalism that determines the type of measurements that yields optimum determination precision. SAF is applied to ellipsometric- scatterometry of surface relief gratings and for the optimum measurement configuration predicts a significant improvement compared to the conventional scatterometry measureme...
Article
The sensitivity analysis of fitting (SAF) is a formalism that determines the type of measurements that yields optimum determination precision. SAF is applied to ellipsometric- scatterometry of surface relief gratings and for the optimum measurement configuration predicts a significant improvement compared to the conventional scatterometry measureme...
Article
The zeroth-order cross-reflection coefficients of a surface-relief grating are shown to be equal from experimental evidence and numerical evidence by use of rigorous coupled-wave analysis simulations. This result is valid for any range of grating parameters as well as for anisotropic media that have the optic axis in the surface plane. This result...
Article
The intensity of radiation diffracted from periodic structures is extremely sensitive to slight variations in the geometry and composition of the diffracting structure. Rigorous diffraction theory provides a mechanism for accurate analysis of the scattered waves. Scatterometry is a metrology technique that combines the sensitivity of diffraction fr...
Article
Scatterometry, the analysis of light diffraction from periodic structures, is shown to be a versatile metrology technique applicable to a number of processes involved in the production of microelectronic devices, flat panel displays, and other technologies which involve precise dimensional control of micron and sub-micron features. This paper revie...
Article
We describe a modification to our existing scatterometry technique for extracting the relative phase and amplitude of the electric field diffracted from a grating. This modification represents a novel combination of aspects of ellipsometry and scatterometry to provide improved sensitivity to small variations in the linewidth of subwavelength gratin...
Conference Paper
We have shown the applicability of optical scatterometry to provide a metrology technique that satisfies many, and sometimes all, of the requirements needed. Scatterometry is a two-step process in which a sample having periodic structure is illuminated. The diffraction characteristics are extremely sensitive to the dimensional and optical structure...
Article
Conventional scatterometry measures the intensity of a diffraction order from a periodic structure as one or more measurement parameters is changed. We have previously demonstrated conventional techniques to characterize developed photoresist linewidths as small as approximately 0.15 micrometer, with scatterometer results agreeing well with measure...
Article
The effort discussed here addresses the use of shorter incident wavelengths for characterizing sub-0.1 μm linewidths and the corresponding influence on scatterometry measurement sensitivity to linewidth variations. A sensitivity metric, based on the variance statistic, was developed using well-characterized, large-pitch (0.80 μm) photoresist gratin...
Article
The silylation step in the top surface imaging process has been difficult to monitor and characterize for lack of appropriate metrology tools. Utilizing scatterometry to measure silylated wafers, we report successful monitoring of processing effects. Wafers were manufactured under nominally identical processing conditions. Applying scatterometry, w...
Article
Optical diffraction tomography (ODT) attempts to reconstruct the complex refractive index profile of an object by inverting its backscattered and/or transmitted fields. Owing to its integral formulation of the diffracted plane, the inverse scattering problem in ODT, i.e., reconstructing the object from its diffracted field, can be linearized via th...
Article
In previous applications scatterometry has shown promise as a metrology for several process measurements. The linewidths of both resist and etched features, and the thicknesses of several underlying film layers, have been accurately characterized using the technique(1). Up until recently these results have been obtained by assuming the features bei...
Article
Scatterometry, the analysis of light diffraction from periodic structures, is shown to be a versatile metrology technique applicable to a number of processes involved in the production of microelectronic devices. We have demonstrated that the scatterometer measurement technique is robust to changes in the thickness of underlying films. Indeed, ther...
Article
In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer. This is done by ascertaining the intensities for...
Article
Scatterometry, the characterization of periodic structures via diffracted light analysis, is shown to be a versatile metrology technique applicable to several processes involved in microlithography. Unlike contemporary inspection technologies, such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), scatterometry is rapid, no...
Article
Scatterometry, the characterization of periodic structures via diffracted light analysis, has been shown to be a versatile technique for measuring critical dimensions in photoresist as small as 0.160 micrometer. Rapid, non-destructive and inexpensive, scatterometry has the potential to be applied to other microlithographic features as well. This pa...
Article
Scatterometry, defined as the angle resolved characterization of light scattered from a surface, is an attractive tool for the metrology of semiconductor devices. It is simple, rapid, non destructive, relatively inexpensive and can be used in-situ. This paper illustrates the use of scatterometry to characterize fine pitch gratings having linewidths...
Article
A scatterometric sensor measures the intensity of light diffracted from a periodic structure. When applied in-situ to the post exposure bake (PEB) process for chemically amplified resists, a scatterometric sensor can monitor the formation of a latent image. Sturtevant, et al and Miller, et al have shown that this application of scatterometry is via...
Article
Scatterometry, the characterization of periodic structures via diffracted light analysis, is shown to be a versatile metrology technique applicable to several processes involved in microlithography. Unlike contemporary inspection technologies, such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), scatterometry is rapid, no...
Article
Scatterometry, the characterization of periodic structures via diffracted light analysis, has been shown to be a versatile technique for measuring critical dimensions in photoresist as small as 0.160 micrometer. Rapid, non-destructive and inexpensive, scatterometry has the potential to be applied to other microlithographic features as well. This pa...
Article
A precise and accurate technique for the characterization of periodic line/space gratings is presented. The technique, known as scatterometry, derives its sensitivity and robustness from the wealth of information present in diffracted optical radiation. Scatterometry is capable of determining width, height, and overall shape of sub-half micron line...
Article
Scatterometry, the analysis of light scaattered by diffraction from periodic structures, is shown to be a versatile metrology technique applicable to a number of processes involved in microelectronic manufacturing. Contemporary inspection technologies such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), apart from being s...
Article
Scatterometry, the analysis of light scaattered by diffraction from periodic structures, is shown to be a versatile metrology technique applicable to a number of processes involved in microelectronic manufacturing. Contemporary inspection technologies such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), apart from being s...
Article
The widths and overall profiles of dielectric grating lines can be determined by measuring the intensity of diffracted laser light from the sample over a specified range of incident beam angles. This technique, known as 2‐Θ scatterometry, is able to accurately and precisely measure photoresist structures in the subhalf micron regime. Moreover, a 2‐...
Article
Metrology of etched quartz and chrome embedded phase shift gratingsusing scatterometrySusan M. Gaspar Wilson, S. Sohail H. Naqvi, John R. McNeilCenter for High Technology MaterialsThe University of New MexicoAlbuquerque, New Mexico 87131Herschel M. MarchmanAT&T Bell LabsMurray Hills, New Jersey 07974Blame JohsJ.A. Woollam Co., Inc.650 J. Street, Su...
Article
Scatterometry, the characterization of periodic structures via diffracted light analysis, is shown to be a viable and versatile metrology for critical dimensions as small as 0.24 micrometers . Scatterometry is rapid, nondestructive, inexpensive, and potentially useful for on- line control during several microlithographic processing steps. This pape...
Article
Advances in memory IC technology for dynamic random access memory (DRAM) devices have come about from a reduction in individual cell thickness with a corresponding increase in cell depth in order to maintain the same stored capacitance value. As the memory size on DRAM devices rises, memory cells must get deeper making the process of measuring dept...
Article
Increased level of integration on dynamic random access memory (DRAM) devices has been achieved by augmenting the number of vertical memory cells used for energy storage. Current methods of implementation include reducing the cell's thickness, while increasing its depth in order to maintain the same capacitance of stored electrical charges. We disc...
Article
Diffraction‐based techniques have been shown to provide convenient, nondestructive, rapid metrology for lithography steps during semiconductor fabrication. Monitoring diffraction from latent images provides the capability to determine exposure tool focus to an absolute accuracy of 0.1 μm. Exposure dose and subsequently post‐exposure bake have also...
Article
Scatterometry is presented as an optical metrology technique potentially capable of determining the critical parameters of a phase etched diffraction grating test structure (sidewall profile, etch depth, and linewidth). The technique is noncontact, rapid and nondestructive. The test grating structure is illuminated by a laser beam and the intensiti...
Article
Scatterometry, the analysis of light scattered by diffraction from periodic structures, is shown to be a versatile process control and metrology technique for use in microelectronics manufacturing. Contemporary inspection technologies, such as scanning force microscopy (SFM) and scanning electron microscopy (SEM), in general cannot be performed in-...
Article
Scatterometry is shown to be a viable alternative to current methods of post-developed line shape metrology. Five wafers with focus-exposure matrices of line-space grating patterns in chemically amplified resist were generated. The gratings were illuminated with a He-Ne laser and, utilizing only the specular reflected order measured as a function o...
Article
We have initiated an effort to develop metrology tools that isolate the effect of each process step. Light scattered from diffracting structures is analyzed to determine characteristics of the structure. The technique is rapid, non-destructive, and extremely sensitive to variations in the samples that were examined. Through our technical collaborat...
Article
The trend towards smaller design geometries for microelectronics devices places unprecedented demands on the measurement of these small structures. Two sample problems are considered. In the first case we predict the shape of developed photoresist gratings from diffraction data obtained from an angle scanning scatterometer in which a detector track...
Article
Quantitative methods are developed to use optical scatter to measure the critical dimensions of gratings etched into bulk Si and developed photoresist patterns on silicon substrates. Previous work either classified microstructures qualitatively or employed a 'chi-by-eye' method to find that structures were similar or dissimilar. A single detector s...
Article
In this paper we discuss an optical metrology technique for the determination of optimum lithography parameters through an interrogation of the latent image. This technique, called the Lithography Process Monitor (LPM), involves illuminating a latent image grating with a laser beam. The intensity of the orders diffracted from the grating has been s...
Article
We present a novel technique for the rapid, nondestructive evaluation of the contrast of the latent image in photoresist. Measurements are made of the intensity of light diffracted from a grating pattern in exposed, undeveloped photoresist, the so‐called latent image. Optimum exposure tool parameters such as exposure tool dose and focus can be dete...
Article
Quantitative methods are developed to use optical scatter to measure the critical dimensions of gratings etched into bulk Si and developed photoresist patterns on silicon substrates. Previous work either classified microstructures qualitatively or employed a 'chi-by-eye' method to find that structures were similar or dissimilar. A single detector s...
Article
We describe an experiment in which the etch depth of a diffraction grating is measured. A simulated experiment is used to develop and calibrate the measurement technique. A scatterometer was used to measure the diffraction patterns of a set of 5 wafers at 14 die locations. The estimator already developed is then used to find the etch depths at the...
Article
Laser scatterometry is a noncontact, rapid method of collecting and analyzing light scattered from a structure. We have applied optical scatter techniques to measure the surface roughness as well as the etch depth of phase shifting masks (PSMs). Experimental results and theoretical modeling are discussed.
Article
The hollow cathode cylindrical magnetron is demonstrated to be capable of depositing uniform coatings on heavy metal fluoride fibers while maintaining the fiber temperature below 150°C. Pure metal coatings were deposited at typically 3000 Å/min, while oxynitride coatings were deposited at roughly 300 Å/min. We also demonstrated the hermeticity of A...
Article
As the microelectronics industry strives to achieve smaller device design geometries, control of linewidth, or critical dimension (CD), becomes increasingly important. Currently, CD uniformity is controlled by exposing large numbers of samples for a fixed exposure time which is determined in advance by calibration techniques. This type of control d...
Article
We have applied optical scatter techniques to improve several aspects of microelectronic manufacturing. One technique involves characterizing light scattered from two dimensional device structures, such as those from VLSI circuitry etched on a wafer, using a frosted dome which is imaged by a CCD camera. Previously, limited dynamic range available f...
Article
The attempt to eliminate subsurface damage in polished materials is a major objective in optical and semiconductor fabrication. The level of subsurface damage in optical components is proportional to the surface scatter and related to the laser damage threshold of the optic. The float polishing process has been shown to produce surfaces with low su...
Article
The attempt to eliminate subsurface damage in polished materials is a major objective in optical and semiconductor fabrication. The level of subsurface damage in optical components is proportional to the surface scatter and related to the laser damage threshold of the optic. The float polishing process has been shown to produce surfaces with low su...
Article
We discuss the use of light scattered from a latent image to control photoresist exposure dose and focus conditions which results in improved control of the critical dimension (CD) of the developed photoresist. A laser at a non-exposing wavelength is used to illuminate a latent image grating. The light diffracted from the grating is directly relate...
Article
The formation of resist lines having submicron critical dimensions (CDs) is a complex multistep process, requiring precise control of each processing step. Optimization of parameters for each processing step may be accomplished through theoretical modeling techniques and/or the use of send-ahead wafers followed by scanning electron microscope measu...
Article
A novel laser scatterometer linewidth measurement tool has been developed for critical dimension metrology of photomasks. Calculation of the linewidth is based on a rigorous theoretical model, thus eliminating the need for calibrations. In addition the effect of the glass substrate on which the photomask grating is placed is explicitly taken into a...
Article
Identification of dimensional parameters of an arbitrarily shaped grating using scatter characteristics is presented. A rigorous diffraction model is used to predict the scatter from a known grating structure, and utilizing this information we perform the inverse problem of predicting line shape from a measurement of the scatter.
Conference Paper
Ion beam figuring has been demonstrated to be a deterministic efficient flexible technique for removing material from optical surfaces. Recent interest in using this process to produce high quality optical components has driven the need to fully characterize the resulting surfaces. We have performed a polishing parameter matrix investigation to opt...
Conference Paper
Photoacoustic spectrososcopy is used to characterize the surface absorption of polished fused silica substrates and thin films deposited on fused silica substrates. The extreme sensitivity of this technique allows measurement of surface absorptions of a few tenths of a part per million. Characterization of samples with surfaces finished using a var...
Article
Several techniques are available for characterizing the surface microstructure of smooth components. Often it is necessary to compare the results from two or more of these techniques. This can lead to problems unless it is understood that all measurement techniques are bandwidth limited, and each technique has a characteristic transfer function. We...
Conference Paper
The effects of coatings on the optical scatter and related surface microroughness of coated surfaces are examined. Experimental results indicate that coated surfaces, in some cases, are smoother than the bare substrate. A model for smoothing process is presented. The role of deposition mechanism and substrate morphology are discussed.
Article
Heavy metal fluoride glass materials are attractive for optical applications in the near UV through IR wavelength regions. However, many compositions are relatively soft and hygroscopic and possess low softening temperature (250–300°C). We have applied ion assisted deposition (IAD) techniques to deposit MgF2, SiO2, and A12O3/SiO2 thin film structur...
Article
Deposition of 0.2–0.5-µm thick Cu thin films onto a polished Cu substrate causes a reduction of scatter due to high spatial frequency microroughness by as much as a factor of 10 and a reduction in total integrated scattering by as much as a factor of 4.
Article
TiOâ and SiOâ films deposited using ion assisted deposition are investigated as a function of ion energy and current density. Optical constants, possible ion source contaminants, and optical scatter are examined for samples deposited at ambient (approx.75°C) and elevated (approx.250°C) substrate temperatures.
Article
Oxygen ion-assisted deposition of SiO//2 and TiO//2 has been investigated as a function of ion energy (30-500 ev) and current density (0. 300 mu A/cm**2) at the optic. It is shown that both low and high energy ion bombardment improve SiO//2 film stoichiometry, although slightly greater improvement is realized for the low energy case. For TiO//2 fil...

Citations

... Due to its its advantages of non-contact nature, no load force, low surface and subsurface damage, and low edge effects, it has been applied for the finishing of ultra-precision X-ray optics and lithography systems. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In an IBF process, as shown in Fig. 1, the Clear Aperture (CA) is defined as the useful area of an optical surface. Since IBF has no overhang issue, CA is usually enclosed in a larger Dwell Grid (DG). ...
... In contrast, an adequate metrology technique for the aforementioned task is optical scatterometry because it allows the characterization of periodic structures via analysis of the light diffracted from illuminated samples. 5 The unknown structure parameters are reconstructed by the comparison of intensity measurements and simulations of the diffraction process with the samples. Reconstructed values can be geometrical dimensions as well as intrinsic functions like the refractive index dispersion, for example. ...
... La scattérométrie est une métrologie optique indirecte, fondée sur l'analyse de la lumière diffractée sur une structure de test (Figure 3.1). D'un point de vue matériel un scattéromètre est généralement une association de trois éléments : un éllipsomètre, un simulateur électromagnétique de la réponse scattérométrique et des modules de calculs très avancés [68]. La structure de test mesurée forme un réseau périodique de motifs (lignes, tranchées, etc.) permettant d'extraire le profile moyen de la dimension critique par diffraction. ...
... Scatterometry is an attractive inline metrology approach due to the measurement speed and precision [12,13]. ...
... The inverse problem in optical scatterometry has attracted much attention and is considered essential to characterizing the linewidth of L/S patterns. The library search method has been proposed to solve the inverse problem [25], [26]. However, the library search method is limited by the time-consuming nature of its computation, because the method requires numerous theoretical signatures to complete the accuracy measurement [27]- [29]. ...
... Elle n'est autre que l'inverse de la variance du paramètre étudié, pour le bruit considéré dans les simulations. Elle est donnée par l'équation suivante [67,66] : ...
... [2,3] In recent years, there have been a number of studies that have investigated how scatterometry used for overlay error measurement. [4][5][6] It is a non-contact and non-destructive metrology and it has the advantages of higher optical resolution than the image-based optical microscopy. This technology is based on the analysis of light scattered from a geometrical patterns. ...
... Critical elements of these small structures, such as the Critical Dimension (CD), the reproducibility and the uniformity of the structures are areas of concern. Contact metrologies such as Atomic Force Microscopy (AFM), and non-contact metrologies such as scanning electron microscopy (SEM) and scatterometry123456789101112 were developed to fulfil this need. Among these techniques, scatterometry has the advantages of being non-contact, non-destructive and not requiring special environmental conditions such as vacuum. ...
... Modeling has proven itself a valuable and accurate tool for predicting the printability of defects [25,26]. Modeling has also been used to understand metrology of lithographic structures [27][28][29][30] and continues to find new application in virtually every aspect of lithographic research. In fact, modeling has proven an indispensable tool for predicting future lithographic performance and evaluating the theoretical capabilities and limitations of extensions for optical lithography far into the future. ...
... The SBIL is very complex incorporating many high-accuracy control techniques; the phase synthesis technique is simpler, using only several reference gratings for phase alignment. Two years ago, we made an optical mosaic grating by consecutive exposures using diffraction from the latent grating (exposed but undeveloped grating in photoresist) [6,7] rather than from reference gratings as in [5] for alignment. The use of a separate red laser to generate phase alignment beams does not harm the latent grating, but suffers from having different phase drifts between the exposure beams and the alignment beams, which tends to result in additional mosaic errors. ...