Faceted three-dimensional (3D) AlGaN/AlN multiple quantum wells (MQWs) with semipolar {1 ̄101} and polar (0001)
planes are fabricated by a regrowth technique based on metalorganic vapor phase epitaxy (MOVPE) on trench-patterned
AlN templates. Similar 3D microfacet structures with different height are formed on top of and at the bottom of the AlN
trench. Cathodoluminescence (CL) spectra are separately acquired at semipolar and (0001) facet QWs at room
temperature (RT). The peak energies of {1 ̄101} facet QWs and (0001) facet QWs on higher 3D structures are 5.42 and
5.43 eV, respectively, while that of (0001) facet QWs on lower 3D structures is 5.23eV. Through structural analyses
using transmission electron microscopy (TEM), the peak energy difference between the {1 ̄101} QWs and the lower
(0001) QWs is ascribed mainly to suppressed internal electric fields in the {1 ̄101} facet QWs. Furthermore, Al spatial
distribution causes the peak energy difference between the (0001) facet QWs.
Etching characteristics of various resins by a vacuum ultraviolet (VUV, λ=172 nm) light have been examined under
conditions of exposure time, substrate temperature, radiation distance and ambient oxygen concentration. The VUV light
have used to clean the imprinted molds which are contaminated by organic substances such as ultraviolet-resins through
many times of imprinting processes, and it has revealed that the VUV light has effectively regenerated the contaminated
molds manufactured by quartz, silicon-carbide and nickel.
Numerous alternate processes are under industry-wide evaluation as simplifications to current double patterning
methods. Reduction in process complexity and cost may be achieved by use of photoresist stabilization methods that
eliminate one etch step by allowing a second resist to be patterned over the first resist pattern. Examples of stabilization
methods using numerous curing processes have been reported. At least some resist shrinkage during stabilization
appears to be generally observed for these methods. We evaluate the link between volumetric shrinkage and threedimensional
pattern distortion for a variety of resist geometries using experimental and simulation-based methods.
Experimental resists designed for double patterning using 172 nm UV resist curing were evaluated and showed
shrinkage of less than 10 percent. Several simplified metrology approaches for measuring shrinkage as well as inferring
shrinkage distortions were assessed. For top-down SEM measurements, elbow inner corner rounding measurements
appear to be a usefully robust method for estimating shrinkage distortion. Finite element analysis of resist structures
yields shrinkage distortions that are in good qualitative and quantitative agreement with experiments, and thus appears to
provide a provisionally general and useful method for predicting pattern distortions that arise during cure-based resist
stabilization methods used in double imaging.
Many processes are under evaluation as simplifications to current double patterning methods. Reduction in process complexity and cost may be achieved by use of track-based photoresist stabilization methods that eliminate one etch step by allowing a second resist to be patterned over a first resist. Examples of stabilization methods using numerous curing processes have been reported. At least some resist shrinkage during stabilization appears to be generally observed for these methods. We evaluate the link between shrinkage and three-dimensional pattern distortions at line ends and elbow corners using experimental and simulation-based methods. A 172-nm UV resist curing process was used to produce controlled shrinkage ranging from 5% to 30%: shrinkage was correlated with resist distortions. At cure dose sufficient to stabilize the resist, shrinkage of approximately 23% results in measured line-end pullback and elbow displacement of approximately 16% and 13% of nominal linewidth respectively, when measured at resist half-height. Finite element analysis of resist beam structures produces shrinkage distortions that are in good qualitative and semiquantitative agreement with these measurements and thus appears to provide a provisionally general and useful method for predicting pattern distortions that arise during cure-based resist stabilization methods used in double imaging.
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