摘要:

A 27 MHz/2 MHz Ar/CO/CFxrf capacitive discharge was used to selectively etch submicron SiO2/Si, SiO2/TiSi2and SiO2/TiN structures. The borophosphosilicate glass etch rate (∼1.0 μm/min) was observed to decrease with bottom electrode temperature, whereas etch selectivity to TiSi2(≳50:1) was found to increase with temperature, with a photoresist selectivity ≳50:1. Plasma emission of the dual frequency discharge indicated the presence of an abundant concentration of the CF2radical (249 nm) as compared to a lower frequency (400 kHz) rf discharge with low etch selectivity (<20:1). Langmuir probe measurement indicated an enhancement of ion density of an order of magnitude (∼5×1010cm−3) as compared to the low frequency (400 kHz) rf discharge. Particle‐in‐cell simulation was used to calculate plasma density as a function of excitation frequency. Plasma density scales with the square of the source frequency while it remains relatively independent of the substrate frequency.

ISSN:1071-1023    

DOI:10.1116/1.588820

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Insituoptical emission and ellipsometry are used to control the etching of titanium nitride/polysilicon gate stacks deposited on 70 Å gate oxide patterned with 0.25–0.35 μm design rules. Multistep recipes using various chemistries are developed and optimized with a low pressure, high plasma density helicon source in which the goal is to obtain stringent profile control, and high selectivity to the gate oxide. The characteristic real‐time optical emission and ellipsometry traces are used as a reference to evaluate reproducibility and to compare the etching rates as a function of the different processing conditions. Optical emission and ellipsometry appear crucial for the rapid development of a multistep etching sequence using various chemistries. Complementary post‐process diagnostics using a spectral reflectometer for film thickness measurements and scanning electron microscopy for quantification of profile control are also presented.

ISSN:1071-1023    

DOI:10.1116/1.588821

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Evolution of etched profiles has been numerically investigated during electron cyclotron resonance (ECR) Cl2/O2plasma etching of polycrystalline Si. The calculations included the processes of chemically enhanced ion etching and passivation layer formation, which are important in such low‐pressure, high‐density plasma etching environments. The sidewall passivation was modeled by taking account of the redeposition of etch products on sidewalls of etched features. In addition, the effect of surface oxidation was also included in the model. Etched profiles were then simulated to examine effects of the neutral‐to‐ion flux ratio onto the substrate, sticking coefficient of etch products, and additional incident fluxes of etch products and oxygen atoms. Numerical results indicated that in typical ECR plasma etching environments, where the gas pressure isP0≲1 mTorr and the ion current density isJi∼10 mA/cm2onto the substrate, the chlorinated surface coverage α is microscopically nonuniform on sidewalls and bottom surfaces of etched features: α≲0.3 at the bottom and α≊1 on the sidewalls. This microscopic nonuniformity in coverage was found to lead to inversely tapered etched profiles without any sidewall passivation. These profiles changed to vertical and further tapered, when simultaneous redeposition of etch products were taken into account with their sticking coefficientsSp≳0.1. Furthermore, it was shown that in the presence of oxidation, the sidewall surfaces are easily oxidized, and the lateral etching is effectively reduced during overetch.

ISSN:1071-1023    

DOI:10.1116/1.588822

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The process induced surface microroughness of both the silicon substrate and top surface of 15 nm gate oxide were investigated by atomic force microscopy. Varying degrees of surface microroughness on the Si and on the gate oxide were induced by timed wet silicon etch (750:1 HNO3:HF solution). TheRmsroughness of the initial silicon substrate was<0.2 nm, while the value increased to 0.65 nm after extended etch. For short etch times, the initial Si surface roughness was reproduced at the gate oxide surface. The average electrical field strength required to maintain a fixed current density of 1.5×10−5A/cm2was found to increase with decrease of the gate oxide surface roughness.

ISSN:1071-1023    

DOI:10.1116/1.588823

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

From a standpoint of physical, chemical, and electrical properties, silicon nitride films formed by synchrotron radiation‐excited chemical vapor deposition with SiH4+N2gas mixture are characterized. These properties are compared with the properties of films deposited by other low‐temperature processes. It is found that the present film has such features as lower hydrogen content (<4×1021cm−3), higher film density (2.9–3.05 g/cm3), lower etching rate against BHF (<10 nm/min), and potentially improved electrical properties considering that deposition was performed at substrate temperatures as low as 200 °C. Deposition kinetics, the effect of bias on film properties, and ways to improve the electrical properties are also discussed.

ISSN:1071-1023    

DOI:10.1116/1.588824

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A new theory for oxidation of silicon is derived which is based upon diffusion of molecular oxygen in stoichiometric silicon dioxide, consistent with the mass balance at the silicon‐silicon dioxide phase interface. The results are compared with the experimental data of Lieetal. and Adamsetal.

ISSN:1071-1023    

DOI:10.1116/1.588825

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The long term reproducibility of quantitative secondary ion mass spectroscopy (SIMS) analysis is assessed using three independent analytical procedures important to the microelectronics industry: the determination of oxygen, boron, and surface impurities in silicon. Thousands of measurements acquired from carefully selected statistical process control samples provide an excellent data base. The oxygen measurement yields a repeatability of +2% at a concentration of 28 ppma (instrumental background around 1.4 ppma). A relative standard deviation of 8.3% is achieved for the boron measurement. The boron concentration in the control sample is 5.8 ppba. Many different control samples have been monitored for surface SIMS contamination measurements, and the RSD ranges from 5% to over 100% depending on the element and magnitude of the areal densities. Our results indicate that SIMS is an excellent technique for long‐term process control when rigorous analytical protocols are adopted. The oxygen and boron measurements as well as the measurement of surface sodium, aluminum, and potassium on silicon have been accepted by ASTM as standard procedures. Our analytical protocols have been extended to depth profiling analysis, such as ion implanter dose matching which is an important measurement for the semiconductor industry.

ISSN:1071-1023    

DOI:10.1116/1.588530

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Development‐free vapor photolithography (DFVP) is a unique all‐dry pattern transfer technique, which is based on the reaction of SiO2with HF vapor under a polymer film in the presence of accelerators at a temperature above 100 °C. This article investigates the function of fluorine anions in DFVP. We found that the etching rate was affected not only by the concentration of fluorine anions formed with the help of accelerators, but also by the activity of fluorine anions. Based on this proposal, a novel and more effective accelerator was found. Now, it has been successfully applied to the power electronic device manufacture.

ISSN:1071-1023    

DOI:10.1116/1.588531

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A near‐surface imaging process using wet silylation and oxygen plasma development is described. New characterization techniques of films spun on wafers are presented for: (a) quantitative Si concentration determination using proton nuclear magnetic resonance spectroscopy (H), and (b) glass transition and/or flow temperature determination (Tg) of the silylated photoresist using thermomechanical analysis.H‐line,I‐line, and deep ultraviolet lithography (at 248 nm) results are presented, while extension to 193 nm lithography is discussed. Very anisotropic and high aspect ratio pattern transfer to Si, with fluorine‐only containing plasmas is demonstrated. Possible applications are discussed.

ISSN:1071-1023    

DOI:10.1116/1.588532

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Interferometric lithography, the use of interactions between coherent laser beams to define sub‐ wavelength patterns, is well adapted to the periodic nature of field‐emitter structures. Techniques to fabricate sparse (hole diameter to pitch ratio of 1:3 or larger) emitter arrays to improve reliability and lifetime are presented. These include: multiple exposures at two different pitches; integration of interferometric and optical imaging lithography; and various multiple beam techniques that both provide a sparse array and result in a two dimensional pattern in a single exposure. Moiré alignment techniques are demonstrated to provide a simple process for aligning multiple levels. Manufacturing related issues such as process latitude and photoresist profiles and their suitability for subsequent processing are also discussed. Exposure‐dose process control using latent image monitoring is demonstrated.

ISSN:1071-1023    

DOI:10.1116/1.588533

出版商:American Vacuum Society    

年代:1996

数据来源: AIP