Crystal‐Orientation Dependent Etch Rates and a Trench Model for Dry Etching

Petti, C.; McVittie, J.P.

doi:10.1149/1.2096045

Cited by 33 publications

(26 citation statements)

References 6 publications

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“…It should be pointed out that passivation due to the redeposition of etched products may also lead to trench sidewall tapering, ultimately limiting the maximum depth obtainable. Similar experimental observations, reported by Ulacia et al (13), show that the axial etching stops as the concentration of the passivant is continually increased during the trench etching.…”

Section: Resultssupporting

confidence: 88%

“…Many different passivants have been used in trench etching, including hydrogen, oxygen, hydrocarbons, and SIC14. Inert carbon-based compounds, such as methane, generate deposits from the plasma and decrease the etching rate during silicon trench etching; however, the residue left can damage the surface properties of the silicon (13). Boron trichloride has been employed as an etchant for silicon trench etching, because it generates boron and a polymer containing silicon on the sidewalls (7).…”

Section: Resultsmentioning

confidence: 99%

“…Boron trichloride has been employed as an etchant for silicon trench etching, because it generates boron and a polymer containing silicon on the sidewalls (7). Carbon-containing fluorine or chlorine compounds have been often used in trench etching to inhibit the sidewall etching (6,13). SIC14 has been chosen to passivate the sidewall during silicon trench etching by C12 plasma, and it appears to be a logical choice since the etched products are also silicon chloride species (16).…”

Section: Resultsmentioning

confidence: 99%

“…1, have been formed often by reactive ion etching. An undercut on the sidewall is created by divergent ions scattered by ionmolecule collisions in the sheath (13), while another mechanism involves the scattering of ions from the edge of the mask (15). A combination of these mechanisms may cause bowing on the sidewalls of the trench.…”

mentioning

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Redeposition during Deep Trench Etching

Lii

Jorné

1990

J. Electrochem. Soc.

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In reactive ion etching, redeposited materials from the plasma and the trench can significantly alter the trench profile. A simple model, which takes into account simultaneous ion-assisted etching and redeposition mechanisms, is presented. Using this model, a computer simulation, based on the string-point model, is performed on the evolution of a deep trench profile. The redeposited materials from the plasma and the trench region, coupled with a moving boundary scheme, allow the shape evolution of the etching profile to be computed. The computer simulation shows that defected ions, polymer deposition, and polymer sputtering are important factors in determining the etching profile of silicon trench. Under significant bombardment of deflected ion on the sidewalls of the trench, the redeposited material from the trench is found to be more effective in blocking the etching of the sidewalls during trench etching.Trench formation by dry etching processes is attracting much attention because of the continuously increasing density of circuits and the trend toward three-dimensional devices. The most popular applications are circuit and transistor isolation (1, 2), and high density DRAM storage capacitor (3). However, some problems exist in the deep trench etching processes, notably, an undesirable etching shape, a decrease in the etching rate, and surface contamination (4).Although the technique of plasma etching is widely used in semiconductor fabrication, the control of the process outputs is largely empirical. In spite of many attempts to describe trends in plasma etching and because of its complexity, the precise nature of plasma etching ~s not fully understood. The difficulty in investigating plasma etching lies in its many variables and the high degree of nonlinearity. In brief, the etching of a surface consists of five fundamental steps: (i) reactants transport to the surface, (ii) reactants adsorption on the surface, (iii) surface reactions, (iv)

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Redeposition during Deep Trench Etching

Lii

Jorné

1990

J. Electrochem. Soc.

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“…The faceting was observed before in a high pressure fluorocarbon inhibitor dominated reactive ion etch ͑RIE͒ process. 8 The other mode is the well-known ion-enhanced process.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and crystal orientation dependence in high aspect ratio silicon dry etching

Blauw

Zijlstra

Bakker

et al. 2000

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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High density fluorocarbon etching of silicon in an inductively coupled plasma: Mechanism of etching through a thick steady state fluorocarbon layer A quantitative study of dry etch behavior in deep silicon trenches in high density plasmas ͑electron cyclotron resonance, inductively coupled plasma͒ at low temperatures ͑160-210 K͒ is presented. The quantitative approach implies etch behavior being studied in relation to the relevant particle fluxes ͑atomic F and O and ions͒ as measured by in situ diagnostics. Two etch modes are observed. In one mode faceting shows up as due to crystallographic orientation preference, i.e., Si͗111͘ being etched slower than Si͗100͘. In the other mode the normal anisotropic ion-induced behavior is observed. Controlled switch from one mode to the other is studied under influence of process parameters like pressure, ion energy, and substrate temperature. The second part of this study deals with aspect ratio dependent etching ͑ARDE͒. Both vertical and horizontal trenches have been taken into account as to distinguish between radical and ion-induced effects. The flux of radical species into the deep trench is governed by Knudsen transport, with a reaction probability of atomic fluorine of about 0.5. As a consequence depletion of the fluorine content at the bottom is the main reason for ARDE. With the bottleneck identified, the plasma process has been readily tuned to the aspect ratio independent etch regime. This regime coincides with the crystallographic preference mode where surface reaction kinetics form the rate limiting step. Detailed surface analysis studies by x-ray photoelectron spectroscopy, in situ ellipsometry, and transmission electron microscopy have been used to characterize the surface reaction process.

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Modeling for Manufacturing Diagnostics

Sharma

1993

Microelectronics Manufacturing Diagnostics Handbook

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Crystal‐Orientation Dependent Etch Rates and a Trench Model for Dry Etching

Cited by 33 publications

References 6 publications

Redeposition during Deep Trench Etching

Redeposition during Deep Trench Etching

Kinetics and crystal orientation dependence in high aspect ratio silicon dry etching

Modeling for Manufacturing Diagnostics

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