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Different etching rates subjected to the poly-Si/W gate-stacks of state-of-the-art inner-gate-recessed-channel-array-transistor under HBr/O2 plasma environment result in the asymmetrical SiBrx deposition on the sidewalls of the gate-stacks, causing both the fluctuation of the critical dimension (CD) and the degradation of electrical properties as a consequence. If a HF cleaning process either cannot completely remove SiBrx or was postponed for a certain period of time after finishing the reactive ion etching of the gate-stacks, asymmetrically deposited SiBrx residue unexpectedly reacted with air to form the oxidized etching residue such as SiOxBry. The growth of SiOxBry film on the sidewalls can eventually affect the gate CD and the overlap capacitance, resulting in the degradation of both saturation current and propagation time (tPD). A simple model for the diffusion of the SiBrx by-product during the asymmetrical etching process and the growth of SiOxBry film as a function of time delay is suggested.