The invention relates to an etching method for forming contact holes with different depths. According to the etching method of the invention, backfilling is performed on partially etched contact holestructures; with ion implantation photomasks at contact hole portions with larger depths adopted, secondary photo-etching is performed, and etching is performed by a certain depth, and thereafter, etching is performed. With the method adopted, the problem of contact hole failure caused by excessively large etching quantity of contact holes with small depths under the condition of simultaneous etching of contact holes with different depths can be solved.