Transformer coupled plasma etch technology for the fabrication of subhalf micron structures

Abstract

A transformer coupled plasma (TCP) source has been integrated into a production tool and characterized for subhalf micron etching of thin films. A planar 13.56 MHz plasma is produced over a wide pressure range of 1–500 mTorr. Langmuir probe measurements below 10 mTorr show ion densities ≳1012 cm−3 and low plasma potentials. These properties are favorable for high etch rates and low damage to device structures. Radio-frequency power is also supplied to the wafer electrode for dc bias control. Separation of the plasma generation and dc bias functions allows the control of microloading effects upon the etch profiles of dense and isolated lines. Performance of the tool is described for the etching of polysilicon and tungsten polycide films on substrates up to 200 mm in size. The evaluated characteristics include etch rate, selectivity, and microloading. The TCP is shown to be an advanced source with the capability for meeting 64 megabit device requirements.

Notching characteristics of un-doped amorphous silicon in high density plasma etching

“…It was confirmed by actinometric OES (optical emission spectroscopy) that the density of Cl radicals varies proportionally with the pressure, a corresponding result [12] was previously reported. On the other hand, the etch rate monotonously decreases with pressure in undoped silicon etching.…”

“…It appears that the etch rate is not affected by Cl radical density but rather by another factor, since chemisorbed Cl atoms prevent incident Cl atoms from diffusing into un-doped silicon thus, the etch rate is not significantly affected by Cl radicals. Considering that a decrease in pressure results an enhanced bombardment effect [12], it can be understood that, rather than radical density, ion bombardment plays a predominant role in undoped silicon etching. This result can be explained by the evident effect of bias power as shown in Fig.…”

Studies of the low-pressure inductively-coupled plasma etching for a larger area wafer using plasma modeling and Langmuir probe

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] These works provide considerable understanding of ICP discharge used in plasma processing. This work is an extension of previous studies.…”

Profile evolution during polysilicon gate etching with low-pressure high-density Cl2/HBr/O2 plasma chemistries

“…1,2 In plasma etching, etch rates and profiles are often observed to depend on pattern feature size or aspect ratio, 2-19 e.g., slower etch rates for larger aspect-ratio features ͑reactive-ion-etching lag͒, [3][4][5][6][7][8][9][10][11][12][13] stronger sidewall tapering for smaller aspect-ratio features, [13][14][15][16][17] more thinning and breaking of gate oxides for smaller aspect-ratio features, 18,19 and vice versa. 1,2 In plasma etching, etch rates and profiles are often observed to depend on pattern feature size or aspect ratio, 2-19 e.g., slower etch rates for larger aspect-ratio features ͑reactive-ion-etching lag͒, [3][4][5][6][7][8][9][10][11][12][13] stronger sidewall tapering for smaller aspect-ratio features, [13][14][15][16][17] more thinning and breaking of gate oxides for smaller aspect-ratio features, 18,19 and vice versa.…”