Tungsten layer etching method

The invention discloses a tungsten layer etching method, which comprises the steps of S1, providing a substrate, forming a plurality of deep grooves in the surface of the substrate, forming oxide layers in the deep grooves and on the surface of a device, and covering the oxide layers with tungsten layers; s2, under the condition of first bias power, etching the tungsten layer by using first mixed gas at a first etching rate; s3, under the condition of second bias power, second mixed gas is used for etching the remaining tungsten layer, and the second bias power is smaller than the first bias power; s4, under the condition of S3, third gas is introduced to deposit a polymer in the deep trench, and the polymer is used for reducing the etched rate of the tungsten layer in the deep trench; and the step S3 and the step S4 are executed circularly until etching is completed. According to the scheme, the problems that in the prior art, etching of the groove dense region and the groove sparse region is not uniform, an