AVS 45th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS-ThP

Paper PS-ThP13
CF@sub 2@, CF Radical Behaviors in a Magnetized Inductively Coupled Plasma and the Correlation with Oxide Etch Characteristics

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Plasma Science and Technology Division Poster Session
Presenter: J.H. Kim, Seoul National University, South Korea
Authors: J.H. Kim, Seoul National University, South Korea
H.J. Lee, Seoul National University, South Korea
K.W. Whang, Seoul National University, South Korea
J.H. Joo, Kunsan National University, South Korea
Correspondent: Click to Email
Fluorine-based plasma has been used to etch SiO@sub 2@ layer in LSI circuit fabrications, and the low-pressure high-density plasma sources are being studied for ultra-fine structure fabrication. It has been known that the high density plasma has low etch selectivity over Si, but recent studies show that the highly selective SiO@sub 2@ etching is possible in the restricted area. However, the etching mechanism was not revealed clearly until now. A key parameter governing the selectivity is believed to be the ratio of (CF@sub x@) density to fluorine atom density and of radical density to ion density. Here, we report the CF@sub 2@ and CF radical behaviors based on appearance mass spectrometry(AMS), actinometry and laser induced fluorescence(LIF), along with the correlation between other species and the etch characteristics in the magnetized inductively coupled plasma which was reported for the highly selective SiO@sub 2@ etching. A 13.56MHz RF power up to 2.5kW was coupled to the 4 turn antenna and generated a CF@sub 4@ or C@sub 4@F@sub 8@ plasma at the operating pressure of 1-10mTorr. The CF@sub 2@ radical increased with the operating pressure and decreased with the main RF power, which were well coincident with the global model simulation. But the rates of increase were somewhat different according to the diagnostics tools. The increase rate measured with AMS was about 1.5 times greater than those measured with LIF or actinometry. This was caused by the plasma perturbation in using the AMS technique, the quartz contamination while LIF or actinometry and so on. We will discuss the CF@sub 2@ and CF radical behaviors with the various plasma process parameters and their correlation between other species and etch characteristics. Especially, we will present the effect of bias power on the plasma chemistry near the substrate.