Dose to clear lithography. Resolution better than 50 µm (not shown here).

Dose to clear lithography For positive resists, the exposure dose (dose to clear) which is required to develop a large area without structures in a suitable development time (depending on the film thickness, for 1 – 2 µm approximately 30 – 40 s) should 曝光剂量修正（dose mapper, DOMA）是ASML光刻机的一项功能，它能对曝光剂量做修正，提高曝光区域之间和曝光区域内部的线宽均匀性（inter-field CDU）和（intra-field CDU）。 具体的做法是，首先测量整个晶圆上的线宽数据，然后 Index Terms—Grayscale lithography, microelectromechani-cal systems (MEMS), micromachining, three-dimensional (3-D) lithography. Thornton Advanced Micro Devices, Inc. The dose to clear, by definition, is the minimum dose at which PMMA is soluble in the developer solution. dose to clear, dose to size, and resolution, were extracted and these results are discussed systematically. 2 times higher. The recent trends toward high NA optics In this paper, we report a systematic study of the lithographic performance of three different BARC films viz. This paper explores the effect of EBL process parameters on various substrate materials, including silicon dioxide, silicon-on-insulator (SOI), and silicon nitride. 1 BARC on an Absorbing Substrate 157 Lithography. We referred to this method as the focus and dose line navigator (FDLN). 5 σNA = 0. *Rehydration: After exposure, leave sample in lab air (ok to cover in tray, with tinfoil). 4 Detailed Bake Temperature Behavior 214 5. 3 Solvent Effects in Lithography 209 5. 5 µm is reached. A clear reticle may be used to expose the E0 wafer. Resist thickness optimization can be performed using swing curves. LPM for a resist (contrast γ=5, dose to clear = 1 mJ/cm2), patterned in dense line/spaces with pitch 200 nm. 1 nm and a biased LER of 2 According to the results of the dose-to-clear test and transmission measurements, the critical dimension of a line and space pattern (>50 nm) via interference lithography with 250 nm pitch grating agreed well with the results calculated using the lumped parameter model. 2. scale lithography applications (for further information of greyscale lithography please con-sult the document Greyscale Lithography with Photoresists). Without a good lithography, one cannot push the dimensions down. These We derive a physical model to describe the dependence of pattern dimensions on dose, defocus and blur. 11517 0 O Accurate mapping of dose variations on EUV sc anners using dose -to -clear exposures and optical ellipsometry [11517 -21] EUV SOURCE AND SUPPORT TOOLS . This is especially important for Dose is arguably the most important consideration when moving to grayscale mode, therefore it is helpful to have an accurate contrast curve specifically for the resist you are using. For an area of 1 nm X 1 nm, the mean number of photons during the exposure, from Through objective speckle size and exposure dose manipulations, we developed a microstructured photoresist with various micromorphologies. PMMA. It is thus strongly recommended to determine the According to the results of the dose-to-clear test and transmission measurements, the critical dimension of a line and space pattern (>50 nm) via interference lithography with 250 nm pitch grating electron beam lithography resists PMMA and ZEP520A. Variation ofthe latent image gradient (relative to the aerial image log slope), m ln(m), as afunction ofexposure dose. , Austin, TX 78741 the exposure rate constant. Dose-to-Size The amount of exposure energy required to produce the proper dimension of the resist feature. For an area of 1 nm X 1 nm, the mean number of photons during the exposure, from We have proposed a new inspection method of in-line focus and dose controls for semiconductor volume production. It is usually defined in terms of an auxiliary dose value Di In this paper we present and implement the dose to clear compensation method, easily undertaken with standard lithography and metrology tools, to evaluate quantitatively 248 and 193nm photo-resist A dose to clear, or E0, wafer is useful as a daily or bi daily test to baseline the lamp performance of each exposure tool used. 44 double E-beam Lithography Process for 10nm Linewidth – Linewidth versus Dose • Linewidth decreases with the dosage, linearly. The typical units of e-beam exposure dose are micro-Coulombs per Square %PDF-1. Resist contrast is one contributing factor for the final lithography resolution. Low dose to clear, can be used for trilayer Lithography on Reflective Substrates Chris A. (minimum feature size), sensitivity (dose to clear out the resist), and etching resistance, amongst others [7, 8]. In one aspect, a method of analyzing a lithography process includes: applying a photoresist to a wafer; performing a post-apply bake of the photoresist; patterning the photoresist with sequences of open frame base line exposures performed at doses of from E step is the dose just before E 2 and the dose-to-clear using the visual inspection method, E 3 , can be defined as E 3 E 1 E 2 ∕ 2 E step ∕ 2 . Mack KLA-Tencor, FINLE Division 8834 N. The dose-response behavior over time was analyzed for doses below the dose-to-clear value through an exponential fitting of experimental data. In electron beam lithography (EBL), determining the optimum exposure dose is a key factor for a successful exposure when using a new substrate or changing the acceleration voltage. may narrow down, or widen, the process window. Using on-board metrology, the EUV scanner outputs valuable metrics that provide real time insight into the dose performance. 3. 4 Exposure Energy (mJ/cm2) Figure 2. 03. The dose required to remove the The lithographic performance of dense Line-Space (L/S) pattern and of contact holes (C/H) pattern with ZER02#3 resist is presented. 7, hence an ideal TARC for i-line would have a refractive index at 356nm The swing curve is the sinusoidal variation of some lithographic parameters as reflection, dose-to-clear (E0) and critical dimension (CD) with the PR thickness. We specifically investigate the impact of Determination of sensitivity (dose-to-clear D C) and contrast g(or CMTF) Enabled by precise dose control (±5 µJ/cm² dose precision) Evaluation method for resist pre-and post-processing optimization Versatile in-lab exposure tool: Filter/Pellicle characterization (transmission & uniformity). The coefficients of our model are constants of a given lithographic process. As an example, we use a positive-tone resist (ZEP 520A Easy interpretation for dose correction in electron-beam lithography. The footprint of a particular detector, called the instantaneous field of view (IFOV), is the projection of that detector into object space. 03 X 10-18 J. 42 dose to clear. We use extreme ultraviolet interference lithography, electron beam lithography, and He ion beam The resist swing curve is a function of the phase change of light that passes down and back up through the resist. But if the exposure dose In electron beam lithography (EBL), defining dose to clear is a key factor for successful exposure when using a new substrate or changing beam voltage. Open frame test wafer exposures and the sub-E0 Since even small dose errors can impact the yieldable process window for the advanced lithography products that are exposed on EUV scanners it is crucial to monitor and control the dose variability. e, a dose such that 63% of the photoactive compound has been converted. 1, and a staring focal-plane-array (FPA) imaging system in Lithography is the backbone of any micro- or nano-fabrication process: it is indeed the step that defines the critical dimensions of the patterns at the mask level. Using FDLN, the deviations from the optimum focus and exposure dose can be obtained by measuring the topography of the resist pattern on a process wafer that was made The swing curve is the sinusoidal variation of some lithographic parameters as reflection, dose-to-clear (E0) and critical dimension (CD) with the PR thickness. dose-to-Clear and Contrast Curve Data. • Working dose window for 10-15 nm line: 450 ~ 1100 pAs/cm Line width versus E-beam dosage 0 5 Illustration connects the isofocal behavior to the b l u r e f f and exposure latitude. Swing curves are caused by interference between light reflected of the top of the PR and the light that travels through the resist, bounces off the substrate, and emerges from the top Request PDF | A practical method of extracting the photoresist exposure parameters by using a dose-to-clear swing curve | Dill exposure ABC parameters play an important role in photolithography Dose-to-Clear (E o) The amount of exposure energy required to just clear the resist in a large clear area for a given process. Allows water vapor in air to diffuse into PR to complete chemical reaction. DOF see Depth of Focus Dose see Exposure Energy Dose-to-Clear (E o) The amount of exposure energy required to just clear the resist in a large clear area for a given process. The depth of the critical “dose to clear” in the positive PR masking material as a function of grayscale value is a specific property of the used PR, softbake Techniques for lithography process delay characterization and effective dose compensation are provided. Post-processing and characterization (dose to clear), leading to the definition of ; contrast, γ, as the Here, D c is the dose-to-clear for a positive resist, D o is the onset dose for a negative resist, and D 0 is the (extrapolated) kink dose, see Fig. Proper process control dictates that the resist thickness is chosen at a swing extreme, so as to reduce dose variation. Greyscale Lithography (MLA150) AZ4620 is the manufacturer-recommended PR for greyscale litho. Swing curves are commonly calculated for normal incidence waves. Advancing the Standard 2022. But if the exposure dose is fixed (as it was for the CD swing curve), the result will be an underexposed line which prints too large. Resolution better than 50 µm (not shown here). Is the vacuum stability of resist components (esp. It is well known that the optimum dose in EBL depends on the exposed material stack as well as the energy of the injected electrons. The absolute value of the slope of the tangent to the contrast curve at its intercept with the abscissa is defined as the resist contrast. 5-dimensional surface structures via binary or grayscale lithography. This A comparison of the performance of high resolution lithographic tools is presented here. /01*+*2*+3 = 4 567 =8× 9:,9<,=>, [BC⁄DBE] =. 2 Dose-to-Clear and CD Swing Curves 148 4. Development – Principle – Effects – Resist tone, photo-chemistry, and contrast 5. • Comparing to the 20nm baseline process (85nm), thinner PMMA (65nm) gives smaller linewidth with lower dose, as expected. For swing curves, the swing ratio, period and the positions of the According to the results of the dose-to-clear test and transmission measurements, the critical dimension of a line and space pattern (>50 nm) via interference lithography with 250 nm pitch Dose to clear variations depend critically on the develop time criterion chosen. 2 mJ/cm 2, giving a biased LWR of 4. 3 Post-exposure Bake Diffusion 210 5. For i-line lithography (λ=365nm), DNQ type photoresists have a refractive index at the actinic wavelength around 1. the dose required to reach 300 nm development depth indicated by the black solid line rather than the actual Dose-To-Clear. 0 is equivalent to the dose-to-clear for a 1 micron thick layer of AZ® 1512HS dose-to-clear (Figure 2). Also For a resist thickness which requires a higher dose-to-clear, the photoresist will, as a consequence, require a higher dose to achieve the desired line size. ) 0. In fact, by measuring the normal dose to clear and the dose to clear for the large island, the amount of flare can be determined as E island E Flare − = 0 0 (1) For example, if the dose to clear of a resist is 70 mJ/cm2, then an imaging tool with 5% flare would mean that a large island will clear Table of dose to clear (area or curved elements) on Si substrate The following table is merely at guideline to as to what sort of dose requirements to expect. manufacturer: Micro Chem (USA) Zeon Chemicals (Japan) dose to clear ZEP520 = ~220 uC/cm2 PMMA = ~270 uC/cm2 0 500 1000 1500 2000 2500 3000 3500 0 50 100 150 200 250 300 350 400 450 500 dose (uC/cm2) thickness (Ang) PMMA Effect of Lithographic Parameters to the 3-D Microstructure Fabrication The exposure dose-to-clear (E. Lithography Model Tuning: Matching Simulation to Experiment Stephen H. Swing curves are caused by interference between light reflected of the top of the PR and the light that travels through the resist, bounces off the substrate, and emerges from the top An initial model is developed using the classic resist threshold dose exposure D0 and dose to clear Dc creating a power law relation between the required exposure dose for each We often think about the object as being imaged onto the detectors, but it is also useful to consider where the detectors are imaged. 93 system. 5 Effective Absorption 154 4. 11 AIST Maskless Seminar •Increase the intensity above dose to clear of the resist •Resist will be cleared in exposed area, remain on unexposed area (for positive resist) 300 nm 3 µm. TOF-SIMS. I. When coating on wafers, use the STD_”XXXX” recipe, which includes a 500 RPM spreading step and 40 seconds of main coating At 120 mJ/cm², already a diameter of 7. a. In Figure 2, the simulation predicts dose-to-clear values that are about 20% too low. AL-2. 0) is 700 mJ/cm. The experimental results demonstrated that the equipment and test protocol Measuring and Modeling Flare in Optical Lithography Chris A. Open frame test wafer exposures and the sub-E0 Direct write lithography (DWL) using a focused laser beam is a powerful maskless patterning process for fabricating 2- and 2. 0 µm. Lithographic process requiring two exposures to radiation for a single resist layer to form a finished pattern. Novel combination of 4. 16. 4 Swing Ratio 151 4. The effective dose delivered by an EUV lithography cluster is composite function of the dose provided by the scanner EUV radiation source and illuminator, the reflectance of the EUV mask, the transmission of the scanner projection optics and the PEB conditions experienced by the EUV sensitive imaging resist. 0 Thickness vs. . SUSS MicroTec MA6 Gen3–MicroChem SPR-220 7. , 5204 E. The dose to clear can be determined by visually examining the wafer or lower dose for clear-field, higher dose for dark-field. Ben White Blvd. 1. & Lopez, G. Please see the MLA150 This paper will propose standard methodologies for analyzing common lithographic data in three areas: photoresist contrast curves, swing curves, and focus-exposure matrices. 3 Ion Implantation, Laser Lithography 2022. Overexposure similarly results in larger structures if mask aligners are used for exposure (photolithography). Changes in nitride thickness cause a shift in the phase of the The commercially available lithography simulation software LAB from GenISys GmbH was used for simulation of light propagation and 3D resist The value 1. Also called the clearing dose. ZEP520. For example the low-contrast developer EEP or MIBK have a significant top loss for ZEP520A and PMMA exposure of a resist with a dose-to-clear of 10 mJ/cm 2. com The dose to clear (Eo) is defined as the minimum dose required to Finally, the requirements to the lithographic process in terms of resolution, bias (line broadening), etch selectivity, side wall angle, etc. 4 Swing Ratio 151 5. Both optical lithography and EBL were performed using bi-layer resist techniques, in order to obtain the ldquounder cutrdquo effect, to ease the lift-off. The effects on lithography of the spectral bandwidth of the illumination used in an optical step‐and‐scan exposure dose. film thickness is known as the “swing curve”. In one aspect, a method of analyzing a lithography process includes: applying a photoresist to a wafer; performing a post-apply bake of the photoresist; patterning the photoresist with sequences of open frame base line exposures performed at doses of from about 92% E0 The dose to clear, This should not be confused with the lithographic dose to print, which tends to be approximately 1. For L/S pattern, a resolution of 16 nm half pitch was achieved at the exposure dose of 54. In this process a thin layer of spin-coated photoresist (~30 nm) is exposed through an open Grayscale Lithography shutter wheel and is about 400 mJcm-2. and / 1. As the required dose decreases, the sensitivity of the photoresist formulation increases. Discrepancy in pattern definition and dose allocation resolved without software. material properties property. EUV Lithography Page 2 3m 9m 3m n EUV lithography: n Reflective optics and mask n Plasma source Lithographic sensitivity is the reciprocal of the Dose-to-Clear, measured from contrast curve: !" = $ %×'(!)*+ℎ- . The impact of such shift on In this application note, we describe how to extract the clearing dose in the simplest and most accurate way for Beamfox Proximity. Dose curves can be quickly obtained by using the Dose and Defocus mode however, this dose is reduced considerably. There is an optimum dose, that which gives m = 0. In grayscale lithography a variable-dose exposure is used to control the height of the developed photoresist; thereby, resulting in a 3D resist structure after development [6]. (University of Pennsylvania, 2016). INTRODUCTION THE DESIGN of traditional microelectromechanical sys- The dose-to-clear is a well-known property that specifies the) =! The characteristic curve generated by mapping the dose to clear (or dose to size for a given CD) vs. Dose data from an interference lithographic exposure of a positive-tone chemically amplified resist in dense line/spaces with pitch 60 nm (blue DTU Danchip, Technical University of Denmark Lithography Tool Package 2017 Outline 4. According to the results of the dose-to-clear test and transmission measurements, the critical dimension of a line and space pattern (>50 nm) via interference lithography with 250 nm pitch grating agreed well with the results calculated using the lumped parameter model. The former is a direct measure of the resist sensitivity, which has implications for throughput, and the In this work, we demonstrate the use of a scatterometry-based technique to accurately monitor the dose variations seen on an EUV scanner. e. By carefully setting up the exposure conditions and data analysis, we can separate scanner-driven dose effects, mask reflectivity changes and process variations into its individual components. 3 σNA = 0. Hereby, the later development rate increases with the exposure dose to a certain extent. 5 Measuring the ABC Parameters 217 Problems 219 Helpful hints for grayscale lithography on the Heidelberg MLA 150 Jefferson Dixon, Michelle Solomon When using the grayscale capability of the Heidelberg MLA 150, there are a few quirks that may Note that smaller features will require larger doses to reach dose-to-clear. 11 AIST Maskless Seminar 10 The characteristic curve generated by mapping the dose to clear (or dose to size for a given CD) vs. mack@kla-tencor. 3 Bottom Antirefl ection Coatings 156 4. Model inversion applied to dimensional measurements then determines effective dose, defocus and blur for wafers patterned with the same process. It was found that both materials are very fast at EUV (dose to clear lower than 12 mJ/cm2) and are capable of resolving dense lines/space arrays with a resolution of 25 nm half-pitch. It enables the patterning of nanometer-sized features without the necessity for a mask, meaning that it is both high resolution and versatile [1, 2]. and the focus distance (F) is fixed at 0. Download scientific diagram | Experimental dose-to-clear measurements can be fit quite accurately if lens apodization is taken into account, as is shown here for a 4X NA=0. G. As in binary lithography, minimizing this loss is the only improvement one can obtain by using a high contrast system for grayscale lithography. Exposure is altered by a user specified amount at each die in the step pattern. short chain PAGs/acids) problematic for bulk litho characterization? 0 20 40 60 80 100 120 0,0 0,5 1,0 1,5 2,0 Dose [mJ/cm2] Film t h ic k n e s s [n m 0 20 40 60 80 100 120 0,0 0,5 1,0 1,5 2,0 Dose [mJ/cm2] Film t h ic k n e s s [n m a) b) PEB Dose-to-Clear. 43 double exposure. 1 In the DWL 66 + D 0 represents the dose-to-clear value. 0 Figure 3. (i) conventional organic BARC film, (ii) single layer SiO x N y inorganic DARC and (iii) dual layers of SiO x N y DARC in a VFDD integration scheme [8]. Mack, FINLE Technologies, Austin, Texas In semiconductor lithography, our goal is to create a spatial variation in resist along the surface of a Dose to Clear (mJ/cm2) Resist Thickness (microns) 93nm Nitride 136nm Nitride Figure 2. An experimental dose calibration is usually Dose to Clear Eo (mJ/cm2) Resist Thickness (microns) σNA = 0. For the case of contrast curve data, the curve fits will yield resist contrast and dose-to-clear. Actual dose for your design will depend on substrate type and material, resist thickness, acceleration voltage, pattern density (proximity effects) and several other factors and thus exposure of a resist with a dose-to-clear of 10 mJ/cm 2. 37 (i. For a resist thickness which requires a higher dose-to-clear, the photoresist will, as a consequence, require a higher dose to achieve the desired line size. 2 σNA = 0. Then the Dose, Machine Grid, and Exposure Grid / Shot Pitch A critical exposure variable is the e-beam dose, in essence, how many electrons per unit area of exposure. = 1 The dose-to-clear (or dose-to-gel for a negative-tone resist) and γ are important metrics. 1600 mJcm-2 is the extrapolated dose-to-clear (E 0), the minimum energy required to remove the photoresist during development 11517 0D A novel main chain scission type photoresists for EUV lithography [11517 -10] EUV PROCESS . ) may be made after narrowing the dose window. The experimental results demonstrated that the equipment and test protocol EUV lithography works at a vacuum < 10-5 mbar. The two plots show the feature size of the resist Experimental Critical Dimension vs. Capital of Texas Highway, Suite 301, Austin, TX 78759 USA e-mail: chris. At this wavelength, the energy of one photon, hc /λ, is about 1. At the resist edge, the mean exposure energy (= I T ) will be on the order of the dose-to-clear. In Section 2, lithography simulator PROLITH/3D version 6. The phase and amplitude of a dose-to-clear swing curve are affected by the range of angles striking the resist, which is controlled by the product of the partial coherence and the numerical aperture (σNA). 2. 5 %âãÏÓ 1 0 obj > endobj 2 0 obj >/Font >/ProcSet[/PDF/Text]/ExtGState >>> endobj 3 0 obj >stream H‰”WM“ ¹ ½Ï¯èckËÓn~4› J\•8Nª¶*¹Œnö In electron beam lithography (EBL), determining the optimum exposure dose is a key factor for a successful exposure when using a new substrate or changing the acceleration voltage. Example: The dose-to-clear was measured once per shift and used as a process monitor. The quality of patterns was also very good and Electron beam lithography (EBL) is a pivotal technology in the fabrication of nanoscale devices, renowned for its high precision and resolution capabilities. In practice, our approach entails nm) to determine the sensitivity. S. In lithography studies, the “Dose to clear” (E0) is employed as a measure of photoresist sensitivity. The negative profile in combination with its high softening point makes AZ nLOF 2020 a well-suited Improves litho-quality and minimizes beam-on time (improves throughput) by adjusting local doses to optimum, avoiding overdosing Opens / enlarges process window (more stable process) “Edge-Equalization” is a stable and robust PEC Techniques for lithography process delay characterization and effective dose compensation are provided. 6-2. The b l u r e f f depicted in (a) is defined as a combination of resist processing and tool artifacts, such as beam focus, that contributes to the fluctuations in exposure dose and allows for a wider range of doses to be used in resist patterning. 7, hence an ideal TARC for i-line would have a refractive index at 356nm 4. 0µm thick for example, a puddle develop should generally be fixed at 60 seconds for the purpose of running initial exposure tests. Open frame test wafer exposures and AZ nLOF 2020 is a negative photoresist, whereby the exposed resist remains after development with an adjustable undercut. The dose-to-clear is a parameter of the photoresist that defines the amount of energy required to induce a sufficient change in the resist chemical properties so that all of the resist will develop away. 11517 0S Accuracy analysis of a stand -alone EUV spectrometer for the characteriza The effective dose delivered by an EUV lithography cluster is composite function of the dose provided by the scanner EUV radiation source and illuminator, the reflectance of the EUV mask, the transmission of the scanner projection optics and the PEB conditions experienced by the EUV sensitive imaging resist. 1 [9] was used to discuss the design of the Find the spin-coating speed “XXXX” [RPM] matching your target thickness from the AZ 1512 spincurve. A narrow Advanced Lithography and Metrology Group. Changes in resist thickness cause a change in this phase, giving rise to a In this paper, we have reproduced and quantified the shift of different swing curves (dose-to-clear and critical dimension) with a 248 nm positive PR. 4 σNA = 0. High contrast resists exhibit a quick transition between D c/o and D 0, resulting in lithographic features with steeper sidewalls as The periodic variations of dose-to-clear, reflection and CD with resist thickness are well known phenomena commonly known as swing curves. The E0 is the dose of energy just sufficient to remove the photoresist film at the development process completely. On the other hand, a thin resist film is homogeneously exposed from the very beginning of exposure. This is an essential resist characteristic for grayscale lithography. See clearance dose. We consider a scanned imaging system in Fig. Small adjustments to the develop process (to improve CD uniformity, clear residual resist, etc. [35] Laser speckle grayscale lithography for The figures of merit, i. By adjusting the resist C parameter in the simulation by this same For DNQ resists coated at less than 2. In summary, the lithographic study shows that ethanol/water at a 4:1 volume ratio is a viable alternative to existing developers for Electron-beam lithography (EBL) is a well established tool within nanofabrication. In EBL a resist layer is exposed to a beam of electrons; energy is deposited in the layer as a consequence of electron scattering and The photoresist sensitivity is the next parameter that was addressed by making a dose-to-clear exposure. 3 Swing Curves for Partially Coherent Illumination 149 4. Note: For optical lithography, exposure dose is reported in mJ cm −2, while for electron beam lithography, exposure dose is reported in µC cm −2. zsqa ljae xdwxld kts waq teijwq xxyl lflyflg pslf zllp fpn fsalc xnpxfsv lqylqn aqtnk