are fluctuations of amplitude in the powers however there is no disconnection in the power on the other hand when the modulation index u201c m u201d has a relative high value the minimum amplitude u201c b u201d of fig5 becomes a substantially zero such that the power is not transferred namely when the modulation index u201c m u201d has a relative high value there are much fluctuations of amplitude in the powers accordingly in the present invention the modulation index u201c m u201d has a value greater than 0 5 to have much fluctuations of the amplitude and much variance in acceleration of the ions hereinafter a method of gap filling in a high density plasma chemical vapor disposition hdpcvd device according to the present invention with reference to fig3 and 7 fig7 is a flow chart showing a method of gap filling first in a first step u201c st 110 u201d a substrate u201c w u201d on which a plurality of gap is formed is loaded on a susceptor 120 in a chamber 110 next in a second step u201c st 120 u201d an inert gas such as argon ar helium he and hydrogen h2 is inject into the chamber 110 to stabilize.