摘要:

We describe the first commercial etching system based on a helicon ion source and characterize it for etching organic films in an oxygen plasma. This single wafer etching system achieves a throughput of at least 30 fully processed 5 in. wafers per hour, which is comparable to the throughput of batch reactors. The etching chamber is equipped with a 13.56‐MHz 2500‐W helicon source, four low‐field magnets to shape the plasma and support the helicon wave mode, and a 600‐W radio‐frequency chuck with He backside heat exchange and a temperature range from −50 to +125 °C. Etching rates and uniformity were measured on unpatterned resist‐coated wafers, while trilayer resist patterns were used to study pattern transfer effects. Under nearly optimum conditions we obtain an etching rate of 1.31 μm/min, a throughput ≥30 wafers/h, nonuniformity ≤± 3%, selectivity ≊70 relative to SiO2and nearly vertical etching profiles for all types of features having dimensions down to 0.25 μm. We describe the effect of process variables on etching rate, uniformity, selectivity, and etching profiles. We present a model based on multicomponent adsorption kinetics that fits the observed dependence of etching rate on the process variables. This etching system is being applied to several advanced lithographic schemes including dry‐developed resists, bilayer lithography, and pattern transfer through organic antireflective coatings and planarizing layers.  

ISSN:1071-1023    

DOI:10.1116/1.586054

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

In this article we present a novel acid catalyzed chemically amplified resist and the associated silicon‐dioxide etch process that was developed using that resist. The 200 nm wide and 250 nm deep trenches in the silicon dioxide are part of a multilevel fully planar metallization scheme, where copper lines are fully imbedded in the interlevel dielectric. Conventional resist materials are not sensitive enough to be used in high‐throughput production and in many cases their selectivity versus silicon dioxide reactive ion etching is low. Resist materials based on acid catalyzed chemical amplification show very desirable properties with respect to their sensitivity, flexibility in design, and resolution capability. The resolution capability extends down to 200 nm for 290 nm thick resist presented in this report. Moreover, as such resists meet the requirements of deep UV, x‐ray, and e‐beam exposure tools, it is expected that they will replace the ‘‘standard’’ novolac resists in many applications. A process window for silicon dioxide etching using a single layer resist based on poly(4‐hydroxy styrene‐co‐4‐acetoxymethyl styrene) has been developed. Lithographic sensitivity, resolution, contrast as well as etching characteristics of this resist were evaluated. The resist demonstrated a sensitivity of 2–2.5 μC/cm2for 50 keV e‐beam exposure by the JEOL 5DIIU system. A contrast value of 5.1 was obtained using a postexposure bake of 130 °C for 2 min. The resist selectivity with respect to thermal oxide in CHF3plasma reactive ion etching (RIE) was about 1–3. Using this resist and CHF3RIE we were able to etch 0.25 μm deep and 0.2 μm wide trenches with vertical sidewalls in SiO2. These results showed that the resist system is very feasible for future single layer resist e‐beam pattern definition, and it also has a very promising prospects for deep UV and x‐ray lithographies.

ISSN:1071-1023    

DOI:10.1116/1.586325

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A high‐contrast resist process using polysilynes has been developed for 193‐nm excimer laser lithography. Copolymerization allows for control of both polymer molecular weight and the net polymer solubility parameter. Optimal formulations yield sensitivities of 35–60 mJ/cm2and line‐edge roughness of ≤20 nm. Addition of sensitizers into the resist further improves sensitivity and values from 5 to 30 mJ/cm2have been demonstrated. Use of high‐density, low‐bias etching sources for the oxygen‐plasma pattern transfer improves process windows. For example, etch rate selectivities of 80:1 for the planarizing layer versus the polysilyne imaging layer have been observed even when the planarizing layer etch rate exceeds 1 μm/min. Under these conditions, the exposure latitude is 40% fork1=0.57 and the development latitude is 100% (20±10 s) for 10% linewidth control.

ISSN:1071-1023    

DOI:10.1116/1.586326

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Defect detection equipment and procedures to qualify resist systems with regard to defects have been investigated. An analysis was carried out for two bilayer resist systems which were compared to a single layer resist. One of the bilayer resists was developed for the mid‐UV exposure range, the other for deep‐UV. It showed that the pinhole‐limited yield measured by metal–oxide–semiconductor test structures is approximately 10% lower for one of the bilayer resists compared to a single layer resist. The other bilayer resist scheme was compared to a single layer resist with regard to particulates. Here the dry‐developed bilayer resist scheme showed approximately four times higher additive defect densities than the wet‐developed single layer resist. A short dry etch process for opening an anti reflective coating underneath a single layer resist increased the defect densities. Water rinse steps are capable of reducing these defect levels substantially. The dry‐developed resist schemes had higher defect densities, but it is certainly possible to reduce these to the densities of single layer resists.

ISSN:1071-1023    

DOI:10.1116/1.586327

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A closed‐form, accurate, and easy to fit model for crosslinking of chemically amplified acid‐hardened resist (Shipley SNR‐248) is presented and used to compare effects of e‐beam and optical exposure. In this model, the saturation of the acid‐catalyzed crosslinking reaction during the postexposure bake is assumed to be caused by the ‘‘cage‐effect’’ mechanism–restriction of segmental diffusion of the polymer chains as the reaction progress. [D. Seligson, S. Das, H. Gaw, and P. Pianetta, J. Vac. Sci. Technol. B6, 2303 (1988)]. To model this cage effect, the rate coefficient in the rate equation is assumed to be a linearly decreasing function of the extent of the crosslinking with the asymptotic saturation level of the crosslinking as a parameter. According to this cage‐effect model, the order of the acid catalyst in the crosslinking reaction of e‐beam exposed SNR‐248 resistsmis 1.37, which is similar to that of the deep‐ultraviolet (DUV) exposed resists (1.42). However, in e‐beam exposed resists, some crosslinking is induced by the electrons during exposure. As a result, this initial crosslinking might contribute to a slightly higher activation energy (0.866 versus 0.694 eV). The equilibrium conversions of the melamine crosslinking sites are also different between the two exposure types. The power of the acid concentrationnin the expression for the equilibrium conversion for e‐beam exposed resists is ∼0.49 whereas in DUV exposed resists,nis 1.1. There is also a difference in the activation energies of the equilibrium constants which suggested the cage effect might have a stronger influence on the backward reaction in e‐beam exposed resists.  

ISSN:1071-1023    

DOI:10.1116/1.586328

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

In this article we will discuss a new high‐resolution aqueous base developable negative tonei‐line photoresist system that has demonstrated subhalf‐micron resolution with commerically availablei‐line exposure systems. The photoresist system consists of a novolak resin, an aminoplast crosslinker, triphenyl sulfonium triflate as the photoacid generator, and 9‐anthracene methanol, a commercially available aromatic energy transfer compound. Using statistical experimental design, data will be presented showing the experimentation required to optimize the formulation and the process in 2.38% TMAH developer (0.263 N). We will report linewidth, dose, and focus latitude data, energy transfer compound effects on contrast, background dissolution along with linewidth tolerance to changes in postexposure bake temperature. Additionally, we will briefly discuss initial phase‐shift mask work that is currently in progress.

ISSN:1071-1023    

DOI:10.1116/1.586329

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

0.35 μm design rule device patterns were fabricated using high absorption‐type positive and negative photoresist with a KrF excimer laser stepper. The main reason for using high absorption‐type photoresist was to minimize the thin film interference effect caused by high reflectivity of the substrate in the deep ultraviolet region. The positive photoresist was FH‐EX1 (Fuji‐Hunt) and negative photoresist was SAL601. Both contain novolac resin as the base polymer. The positive photoresist was mainly used for poly‐Si and W–Si layer pattern fabrication and the negative photoresist was used for the contact hole pattern fabrication. In the contact hole fabrication a surface image transfer technique was used. This technique relies on the direct transfer of the surface negative photoresist image to the insulating layer with highly anisotropic etching and is completely different from the so‐called ‘‘surface imaging technique’’ using gas phase silylation and successive dry resist development (O2reactive ion etching). Although the process was a tentative one, critical dimension controllability of this approach satisfied research and development level device fabrication requirements.

ISSN:1071-1023    

DOI:10.1116/1.586330

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A new model of polymer silylation is proposed. This model takes into account the reaction of the silylating agent with the hydroxyl groups of the polymer and the relaxation rate of the polymer after reaction. The diffusion coefficient of the silylating agent is supposed to be a function of the expansion of the polymer matrix. At the interface between the silylating agent and the polymer, it is assumed that sorption driven by the pressure of the silylating agent, and desorption driven by the concentration of the silylating agent can occur. The resulting differential equations are solved using a finite element technique and the influence of the main parameters, namely, the reaction rate, the relaxation rate, and the diffusion coefficients is studied.

ISSN:1071-1023    

DOI:10.1116/1.586331

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

We present a novel method of using an electron beam to both functionalize and cross‐link poly(3‐octylthiophene) (P3OT) in a single step to produce submicron scale polymer structures carrying functionalized groups. We have shown P3OT to be a negative electron‐beam resist with a sensitivity of 15–30 μC cm−2. The electrical conductivity of doped P3OT wire structures was measured at room temperature and was found to be in the range 4.0–5.9 Ω−1 cm−1. Electron‐beam exposure of P3OT films containing 7 wt % ofN‐hydroxysuccinimide (NHS) functionalized perfluorophenyl azide 2 resulted in the incorporation of the NHS functional groups in the polymer, as well as cross‐linking. The functionalized submicron structures were found to be weakly fluorescent under fluorescein excitation (450–490 nm), but after treatment with a solution of 5‐(aminoacetamido)fluorescein in ethanol the structures became strongly fluorescent.

ISSN:1071-1023    

DOI:10.1116/1.586332

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Sensitivity, lithographic performance, photoabsorption, and photodesorption of chemically amplified novolac‐based resists have been studied at an exposure wavelength of 140 Å and are compared to poly(methylmethacrylate) (PMMA). Monochromatic exposures of the resists AZ PF514, AZ PN114, and SAL 601 yieldedD0.9values of 2.5–3 mJ/cm2for 0.25 μm thick films. Contrast values ranged from 3 for AZ PN114 to 5 for SAL 601. Photoabsorption measurements of supported AZ PN114 films at 140 Å yield an absorption coefficient of 4.4±0.1 μm−1. Photodesorption of fragment ions induced by 140 Å radiation has been studied in PMMA and AZ PN114 using time‐of‐flight mass spectrometry. It is found that H+, CH2+, CH3+, H2O+, CHO+, C3H5+, and COOCH3+dominate the ion mass spectra photodesorbed from PMMA, while H+, CH3+, H2O+, and CHO+dominate the ion mass spectra for AZ PN114. The mass‐integrated ion desorption yield from AZ PN114 is three times less than that measured for PMMA per photon or 90 times less when expressed per exposure. Lithographic performance of AZ PF514 and SAL 601 has been characterized using a multilayer‐coated 20× Schwarzschild objective and a transmissive Ge/Si mask illuminated by a laser plasma source.

ISSN:1071-1023    

DOI:10.1116/1.586333

出版商:American Vacuum Society    

年代:1992

数据来源: AIP