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This paper presents a temperature sensor core implemented in standard 0.6µm BiCMOS technology. Due to its intrinsic linearity, the sensor is capable of achieving an inaccuracy of −0.065°C / +0.035°C (3σ) over -40°C to 125°C temperature range after calibration in oil bath at two temperatures. The low output resistance of the core, 5Ω typical value, makes its voltage output signal suitable to be processed by a wide range of analogue-to-digital converters. It also allows multiple instances of the core to be stacked providing a trade-off between noise, supply voltage and silicon area

Finely-focused ion beams can be applied for advanced lithography, which provides some advantages over the conventional direct-write electron beam technology. In the focused ion beam technology, however, the ion penetration depth is limited, thus requiring the use of extremely thin resist layers or higher ion acceleration energies. These requirements are often undesirable for the current IC manufacturing processes. One solution to this problem is to exploit the top surface imaging (TSI) technique for dry developed FIB lithography schemes. In this paper, we investigated the novel lithography process, which combines focused Ga^+ ion beam (Ga^+ FIB) exposure, silylation and oxygen dry etching. The negative resist image by dry etching (NERIME) is a TSI scheme for DNQ/novolak based resists and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. The mechanism of the negative image formation in the NERIME was studied by TEM, and found to be mainly due to the creation of a thin gallium oxide layer during the oxygen dry development. The energy dispersive X-ray spectrometry microanalysis has found that gallium was implanted into the SPR660 resist to a depth of 50nm and the oxidised gallium layer has a thickness of approximately 15nm. It is also shown that the NERIME process can resolve nanometer resist patterns down to 65nm and yet maintaining a high aspect ratio. The NERIME process could be a useful nanofabrication method alternative to the current lithography processes.

A focused-ion-beam (FIB) machine is a versatile tool used extensively in the integrated circuit (IC) industry for conducting failure analysis, prototype fabrication, and device repair. Lithography can also be performed using FIB for direct patterning of photoresists without using a mask. The FIB technique has several advantages over other maskless processes, such as direct-write e-beam lithography; ion-beam patterning of the photoresist offers higher resist sensitivity and lesser backscattering/proximity effects than the e-beam patterning. In this paper, we investigated a new FIB lithography process, called NERIME (negative resist image by dry etching). The NERIME process is a single-layer resist scheme, which implements a Ga+ FIB exposure of DNQ/novolak-based resists, followed by a near-ultraviolet (NUV) flood exposure, silylation, and oxygen dry etching. The NERIME process could not only yield both positive and negative images, but also achieve a nanometer resolution down to 65 nm and a high aspect ratio for the processed patterns. The principle of the negative image formation was also investigated by TEM and found to be due to the creation of a thin gallium oxide mask layer during etching. The NERIME process could be utilized for specific CMOS processing steps for the next generation technology nodes, such as high-resolution lithography over topographical surfaces.

PRIME process with I-line Shipley SPR505A resist was investigated using both simulations and experiments. Modelling of the PRIME process steps for 50-nm lines/spaces grating and 30-nm single line is shown. The liquid-phase silylation step in PRIME with SPR505A resist was experimentally characterised using FT-IR spectroscopy, UV spectroscopy and SIM spectrometry. The silylation agent used was hexamethylcyclotrisiloxane. The results show case II diffusion behaviour of the silicon incorporation in the SPR505A resist. The silylation contrast of the process as determined by the ratio of the silicon uptake in the near UV exposed over e-beam crosslinked regions was found to be 5 to 1.

This paper investigates the effect of various process parameters on the variation in forward current gain lifetime caused by hot carrier generation of BiCMOS bipolar transistors. Statistical process control and statistical designed experiments were used in this evaluation. The device lifetime in reverse bias operation was calculated from the forward current gain. Various process parameters were examined in this work, i.e., the intrinsic base implant dose and energy, selective collector implant dose, collector plug dose, spacer etch ratio, overetch thickness of nitride spacer and emitter poly etch time. It was deduced that high current gain lifetime can be obtained with high base implant doses, high base implant energies, long bulk nitride etch times and short emitter poly etch times.

The electrical properties of fired thick film piezoresistive gauges based on composites of bismuth, indium, cerium and ruthenium oxides are presented. Various material characteristics are analysed, including DC and AC characteristics. The conduction mechanism before and after electroforming is also examined. Structural studies of the fired resistor layers, before and after high field application, are carried out, where evidence of filament growth within the thick film cermet materials is observed. The DC biasing of the MRM device into the negative resistance region shows the ability to produce spontaneous damped oscillations at frequencies up to 3 MHz using a suitable RCL network.

In this paper, Statistical Process Control (SPC) and statistically designed experiments will be used to optimise a recently developed resist schemes i.e., PRIME ( Positive Resist Image by dry Etching ). Orthogonal experiments are designed and conducted in order to produce 0.2 μm lines repeatably in PLASMASK 302U resist. Design rules of 0.1 μm are used due to proximity effects. The data is then explored and analysed using surface plots, boxplots, analysis of variance (ANOVA) and linear regression. It was deduced that e-beam dose and 2nd step etch time were the most significant parameters in the process. Linewidth of 0.2 gm and below were achieved with low values of e-beam dose (250–350μC/cm 2 ) and high values of silylation temperature (205–215°C). The optimum range for NUV flood dose was easily found.

In this paper, simulation of topography effects in photolithography is examined using the two‐dimensional PC based simulator called SLITS (Simulation of Lithography on Topographic Substrates). This program uses FEA software (in‐house written) to solve wave propagation in a photoresist layer and a modified String Algorithm for photoresist development. The simulated results illustrates the effect of topography on the latent and relief images.

The application of software tools in the development of new processes and novel device structures has become a dominant feature in the microelectronics industry. The use of these tools enables technologists to advance optical lithography to submicron levels of IC fabrication, i.e. 64 Mbit DRAMs. In this work, 2D modelling and simulation of optical microlithography on topographic substrates is investigated. A new program called SLITS (simulation lithography on topographic.substrates) has been developed which calculates 2D latent and relief images. The latent image is calculated by solving the Helmholtz equation using finite element analysis. To generate the relief images, new boundary detection and air/resist movement algorithms, which are not features of any traditional lithographic simulator have been designed and implemented. Relief images produced by SLITS and an earlier program ANKAN for a resist on planar substrate are compared and analysed. We also have investigated notching effects in a ph...

Focused ion beams (FIB) have been widely used as a patterning lithography technique for advanced ICs and optical masks fabrication. FIB lithography has certain advantages over the direct-write electron beam lithography in terms of resist sensitivity, backscattering and proximity effects. However, combining the FIB exposure with both Top Surface Imaging (TSI) and dry etching will further extend its advantages towards anisotropic processing of thicker resist layers in comparison to those used by the conventional lithography processes. The newly developed NERIME (Negative Resist Image by Dry Etching) process combines these advantages by the incorporation of focused Ga+ ion beam (Ga+ FIB) exposure, near UV exposure, silylation and dry etching. The work described here follows our investigations into the NERIME process for nanostructure applications and outlines a simplified (two-step) process incorporating FIB exposure and oxygen dry development. The two-step modified NERIME process is a negative working TSI system for DNQ/novolak based resists. Results show that Ga+ ion beam dose higher than 800μC/cm2 at 30keV can modify the exposed resist areas as to withstand the subsequent oxygen plasma etching, thus giving formation of negative resist image. In this study, nanometer resist patterns as small as 30nm with high aspect ratio of up to 15 were successfully resolved due to the high resolution ion beam exposure and anisotropic dry development. The proposed two-step lithography scheme could be utilized for the fabrication of critical CMOS process steps, such as sub-100nm gate formations and lithography over substantial topography.

Focused Ion beam (FIB) lithography has significant advantages over the electron beam counterpart in terms of resist sensitivity, backscattering and proximity effects. However, combining the FIB lithography with Top Surface Imaging (TSI) will extend its advantages by allowing anisotropic processing of thicker resist layers. This paper reports the development of novel single layer lithography process by combining focused Ga + ion beam (Ga + FIB) lithography, silylation and oxygen dry etching. The Negative Resist Image by Dry Etching (NERIME) is a TSI scheme for DNQ/novolak based resists and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. Results show that Ga + ion beam dose in the range of 1μC/cm 2 to 50μC/cm 2 at 30keV can successfully prevent silylation of the resist, thus resulting in the formation of positive image after the dry etching. A negative image can be formed by using a second Ga + ion beam exposure with a dose higher than 900 μC/cm 2 at 30keV to pattern lines into the original exposed resist area. It was observed that resist regions exposed to such high doses can effectively withstand oxygen dry development, thus giving formation of negative resist image. In this study, nanometer resist patterns with high aspect ratio up to 15 were successfully resolved due to the ion beam exposure and anisotropic dry development. This novel TSI scheme for ion beam lithography could be utilized for the fabrication of critical CMOS process steps, such as deep isolation trench formation and lithography over substantial topography.

In this work, the authors explore the application of tetramethylammonium hydroxide (TMAH) developer chemical as a staining agent to enhance the top-down contrast of a silylated pattern to optical detection. When examining a silylated latent image top-down, the topographical differences generated due to the swelling of the silylated region are relied upon to identify pattern details. However, for lower exposure energy or shorter silylation times, there may not be sufficient silicon incorporation to allow clear identification of specific structures for cleaving. The authors have used the TMAH staining technique proposed by La Tulipe et al. to enhance the relief top-down, thereby facilitating analysis of even mildly silylated samples. Results will be presented illustrating the contrast enhancement after staining. Cross-sections of film profiles after aqueous silylation of an I-line photoresist with a solution of hexamethylcyclotrisilazane will also be generated.

Top Surface Imaging (TSI) is a well-established technique used to improve resolution for optical, ultraviolet and electron-beam lithography. The Positive Resist Image by Dry Etching (PRIME) is an advanced lithographic process incorporating electron beam exposure, near UV flood exposure, silylation and dry development. In this paper, the liquid-phase silylation process step in PRIME with Shipley SPR500A-series resists has been experimentally investigated as the most critical part of the process. FT-IR spectroscopy, UV spectroscopy, SIM spectrometry and cross-sectional SEM and TEM were used to characterise the silylation process. Electron-beam exposure with dose in the range of 25-100μC/cm2 at 30KeV was used to crosslinks the resist. Results show that an e-beam dose of 50µC/cm2 was sufficient to prevent silylation in the crosslinked areas. Two bifunctional silylating agents, the cyclic Hexamethylcyclotrisilazane (HMCTS) and the linear Bis[Dimethylamino] dimethylsilane (B[DMA]DMS), were examined and found that they silylate SPR505A much more efficiently than the previously reported Hexamethylcyclotrisiloxane (HMCTSx). The silylation contrast of the PRIME process using HMCTS silylating agent and SPR505A resist was found to be 11:1. The obtained silylated profiles of 1mm lines/spaces gratings for Shipley SPR510A resist have almost vertical sidewalls resulting in very high contrast between the silylated and unsilylated parts of the resist.

Top Surface Imaging (TSI) is a well-established technique to improve resolution for optical, ultraviolet (UV) and e-beam lithography. The Positive Resist Image by Dry Etching (PRIME) process is a high resolution single layer lithography system incorporating electron beam exposure, silylation and dry development. In this paper, modeling of nanostructures down to 30nm using PRIME with 0.5micrometers thick Shipley SPR505A resist are presented. The simulated profiles have been found to correlate closely with the published experimental data. Moreover, the liquid-phase silylation process step in PRIME has been experimentally characterised using FT-IR spectroscopy, UV spectroscopy, SIM spectrometry as well as cross-sectional SEM and TEM. The impact of different silylating agents on SPR505A is presented for both the UV exposed and e-beam crosslinked regions of the resist. Results show that an e-beam dose of 50(mu) C/cm 2 at 30KeV is sufficient to crosslink the resist and prevent silylation. The silylation contrast using Hexamethylcyclotrisilazane (HMCTS) was found to be the highest (11:1) in comparison with other two silylating agents. It was found that the silicon incorporation in SPR505A resist follows Case II diffusion mechanisms.

In this work, a new 2D resist silylation simulator called STIL II has been developed. This simulator extends the 1D methodologies used in the STIL simulator to two dimensions. The silylation process is modeled asa 2D initial boundary value problem, using Fick's Diffusion Equation to describe the diffusion of the silylating agent, which is then solved using in-house written Finite Element Analysis code. This model comprehends the balance of diffusion and reaction rates in the silylation process due to swelling of the resist film. The swelling effect itself, is modeled as a boundary movement problem with the boundaries, and therefore size, of each 2D element being modified in proportion to the silicon concentration in that region. The output of the STIL II simulator is then applied to previously published experimental dat. STIL II predictions agree well with mask center and mask edge silylation thickness experimental results for an I-line scheme. Silylation contrast has ben sued as an indicator to demonstrate the robustness of silylation processing to defocus effects.

In this work, a new resist silylation simulator called STIL has been developed. This simulator models the silylation process as a 1D Initial Boundary Value problem which is then solved using in-house developed Finite Element Analysis code. In this model, the silylating agent diffusion and reaction rates are recalculate dafter each silylating time- step, (delta) t. The swelling mechanism is modeled as a Boundary Movement problem whereby the swelling in each element is a function of the local silicon concentration in that element. By solution of this system across the exposed area, a 2D profile of the silicon concentration is determined over an exposed linewidth. the simulations from this model are compared to published experimental data.

The physical, electrical, and temperature dependent properties of thick film polymeric materials are presented. It has been shown that the sensitivity of the planar polymer piezoresistive gauges is comparable to that of the metal-foil gauges. Whereas the sandwich (MRM-metal resistor metal) configurations exhibit similar characteristics to those of cermet thick film MRM gauges, The electrical tests were carried out on films in the MRM configuration and have shown the existence of electroforming at voltages exceeding the forming voltage. Further increasing the applied voltage is shown to produce both s-type and N-type negative resistance within the films, depending on the region of operation within the V- I characteristic.

In this paper, a new method to calculate the silylation profile in the PRIME process is presented. New software modules have been added to the 2D simulator SLITS in order to simulate the silylation and dry developed profiles in the PRIME process. The silylation and dry developed profiles for the PRIME process are simulated and compared to experimental results. Simulations were carried out for both e-beam and DUV exposures. Under e-beam exposure, the maximum percentage error between the simulated and experimental results was 13%. Under DUV exposure, the silylation depth at the mask edge can be reduced by increasing the dose thus effectively controlling the resist linewidth. The depth of focus was found to be 0.4 micrometers .

DESIM is an exclusive simulator for the DESIRE process. It can model all the three unit processes i.e. surface imaging (projection/contact, conventional/phase-shifted mask), silylation (positive/negative tone, gas/liquid phase, pre-silylation baking), dry development (single and two step). This paper discusses some of the models and then evaluates the performance of the simulator by comparing the simulated results.

Focused ion beam (FIB) lithography has significant advantages over the electron beam counterpart in terms of resist sensitivity, backscattering, and proximity effects. However, combining the FIB lithography with top surface imaging (TSI) will extend its advantages by allowing anisotropic processing of thicker resist layers. This article reports the development of novel single layer lithography process by combining focused Ga+ ion beam (Ga+ FIB) lithography, silylation, and oxygen dry etching. The negative resist image by dry etching is a TSI scheme for DNQ/novolak based resists and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. Results show that the Ga+ ion beam dose in the range of 1–50 μC/cm2 at 30 keV can successfully prevent silylation of the resist, thus resulting in the formation of a positive image after the dry etching. A negative image can be formed by using a second Ga+ ion beam exposure with a dose higher than 900 μC/cm2 at 30 keV ...

A focused-ion-beam (FIB) machine is a versatile tool used extensively in the IC industry for conducting failure analysis, prototype fabrication, and device repair. Lithography can also be performed by the FIB technique for direct patterning of photoresists, followed by wet or dry development. We studied how the property of resist regions changes during oxygen dry development in the NERIME (the negative-resist-image-by-dry-etching) process after subjecting to FIB-assisted gallium implantation. The NERIME process is a single-layer scheme, in which DNQ/Novolak-based resists are exposed by gallium ions with FIB, followed by near-ultraviolet flood exposure, silylation, and oxygen dry etching. This process can yield both positive and negative resist images. In addition, the NERIME technique can achieve a nanometer resolution down to 80nm and a high aspect ratio for the processed patterns. A scanning-transmission-electron-microscope (STEM) analysis of the resist regions FIB-implanted with gallium ions has reveal...

The positive resist image by dry etching (PRIME) process is a high-resolution positive resist system incorporating deep-UV (DUV)/e- beam exposure, silylation (gas/liquid phase), and dry development. A new method to calculate the silylation profile in the PRIME process is presented. New software modules have been added to the 2-D simulator SLITS (simulation of lithography on topographic substrates) to simulate the silylation and dry-developed profiles in the PRIME process. The si- Iylation and dry-developed profiles for the PRIME process are simulated and compared to experimental results. Simulations were carried out for both e-beam and DUV exposures. Under e-beam exposure, the maxi- mum percentage error between the simulated and experimental results was 137.. Under DUV exposure, the silylation depth at the mask edge can be reduced by increasing the dose thus effectively controlling the resist linewidth. Subject terms: PRIME process; lithography modeling; nanolithography; silylation; dry development.