Mechanism of Radical Control in Capacitive RF Plasma for ULSI Processing

Abstract

The radicals of capacitive plasmas actually used in mass production were analyzed using various measurement systems. The composition of radicals in bulk plasma depends on the gas chemistry, the dissociation process, and interaction with the wall. It is revealed that parent gas (C4F8) is dissociated by multiple collision with electrons according to τ·n e<σv>, where τ is the residence time, n e is the electron density, σ is the dissociation collision cross section and v is the electron velocity. A high-performance etching process, which can realize 0.09 µmφ contact holes with aspect ratio of 11, was achieved using a short residence time to suppress the excess dissociation and the control of deposition species through the addition of O2 to C4F8/Ar plasma as well as the reduction of the density of F radicals through the reaction with the Si wall.

Optical emission diagnostics of etching of low-k dielectrics in a two frequency inductively coupled plasma

“…ICPs for etching of organic dielectrics have to satisfy additional requirements such as to operate in a stable pulsed regime [25][26][27][28] in order to avoid charging of high aspect ratio nano-structures [29,30] or to control the excessive dissociation [31]. In particular it would be advantageous to find a mode similar to the standard H mode in argon plasmas.…”

Study for plasma etching of dielectric film in semiconductor device manufacturing. Review of ASET research project

“…The CF and CF 2 radicals decreased with the increase of O 2 . On the other hand, the absolute density of F was not changed because of the reaction between the Si top electrode and the radicals [20].…”

“…Based on our understanding of the key parameters in etching reactions, some monitoring tools and a simulation were proposed to control and predict the etching process. Table 1 describes the five etch reactors [2][3][4][5][6]. These tools each have specific processes that can form SiO 2 contact holes less than 200 nm in diameter, the aspect ratio (hole depth/hole opening) more than 10 with a 200-mm-diameter wafer.…”

“…C 4 F 8 suffers a multiple collisions while it travels in the plasma until it is pumped out. The total number of collisions ξ can be ξ = τ n e <σv> (2) where the residence time τ is defined by the volume of plasma V, gas flow rate Q, and pressure P.…”

Production of high-density capacitively coupled radio-frequency discharge plasma by high-secondary-electron-emission oxide

“…Among these plasma sources, capacitively coupled radio-frequency (rf) plasma (CCP) sources are the most widely used because the geometry of CCP is very simple and CCP is easily discharged even in the case of dielectric material electrodes. 2 However, CCP has a serious problem of low plasma density that hinders high productivity. That is, without a magnetic field, when a driving frequency f is fixed at a conventional permitted frequency of 13.56 MHz, CCP cannot generate a high density of more than 10 10 cm −3 , whereas the density is proportional to the square of f at fixed applied voltage.…”