The invention discloses a side wall 
etching method for reducing 
heat current carrier injection damage. 
Ion injection is carried out on a side wall deposition layer by using neutral ions, and the 
ion injection direction forms an included angle with the direction vertical to a substrate and is inclined towards the source 
electrode direction, so the 
etching speed on the side wall above a source 
electrode region is higher than the 
etching speed on the side wall above a drain 
electrode region in the side wall etching process, after etching, the cross section width of the side wall of a source electrode is relatively reduced, and the cross section width of the side wall of a drain electrode is relatively increased. After 
voltage is applied on a grid electrode, the intensity of a longitudinal 
electric field generated at the drain terminal is weakened, so 
electron hole pairs are generated through the collision of current carriers accelerated by a transverse 
electric field, and the injection into the grid electrode can be realized by holes under the effect of the weak longitudinal 
electric field, so the grid current formed because of the hot current carrier injection is reduced, and the hot current carrier injection damage of a 
semiconductor device is reduced.