Spatial profiles of neutral, ion, and etch uniformity in a large-area high-density plasma reactor

Abstract

Spatial profiles of neutral density, ion density, and etch rate have been measured in a large-area high-density plasma reactor. Blanket photoresist films on 200 mm wafers are etched by oxygen plasmas in a magnetized inductively coupled plasma reactor. Ion density and relative neutral density are measured by a scanning Langmuir probe and optical probe, respectively. Spatially resolved atomic oxygen density is then measured by optical emission spectroscopy and spatially resolved actinometry. The etch rate is calculated from film thickness measurements taken before and after the wafer is exposed to the oxygen plasma. Ion energy and wafer surface temperature were also measured. The mechanism linking neutral density, ion density, and etching rate is discussed.

Two-dimensional calculation of spatial distribution of neutral atoms for a planar inductively coupled oxygen discharge

“…The neutral atom in an oxygen discharge has a behavior different from that in the monatomic feed gas case like argon. The calculated radial distributions of oxygen atoms are in agreement with the experimental results [1,4]. The profile of oxygen atom is parabolic (peaked in the plasma center) or hollow, depending on the gas pressure.…”

“…Thus, the mechanisms that determine the uniformity of chemically reactive neutrals are of interest. Process uniformity depends strongly on the spatial distribution of both charged and neutral particle densities and velocities, as well as potentials [1,2]. Process uniformity is a key requirement to enable large wafers or flat panels to be processed by plasma.…”

“…Especially spatial distributions of density and flux of atomic oxygen are studied since atomic oxygen plays an important role in various plasma processes like surface modification of synthetics, surface cleaning, growth of silicon oxide films, and etching [1,3,4].…”

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

“…[2][3][4][5][6][7] It has been shown that there is a strong correlation between the radial variation of radical concentration and the yield of a plasma process. 8 Measurements of the relative spatial distributions of radical densities have been constructed using various optical measurement techniques, such as laser induced fluorescence, 9,10 optical emission spectroscopy ͑OES͒, and absorption spectroscopy. 11 OES, which measures the optical emission of species in the plasma, is the most popular semiconductor plasma process diagnostic technique because of its simplicity, high sensitivity, and wide applicability.…”

“…3,[11][12][13] Otherwise, a movable electro-optical probe is inserted into the plasma to directly detect spatial variations in species concentration by collecting the emission of the molecules in front of the probe. 8,14,15 In the present work, we designed an OES that is capable of detecting spatial variations in plasma density, and we constructed this OES with a series of lenses, apertures, and a pinhole as a spatial filter to enhance the spatial resolution. We theoretically verified the spatial resolution capability of the OES, and the results of the calculation were compared with experiments.…”