The present invention discloses a semiconductor photoetching method and comprises the following steps: firstly, silicon nitride is generated on semiconductor silicon, secondly, silicon nitride is coated with photoresist and then photoetching is conducted to generate a groove, thirdly, photoresist is removed and the surface of the device is plated with silicon dioxide; multiple regularly spread point-shaped auxiliary marks are filled in the area of two sides of the groove of the silicon dioxide and then according to the position of the auxiliary mark, the silicon nitride layer, the silicon dioxide layer and the auxiliary mark can be removed with corrosion and chemical and mechanical polishing; at last, photoresist can be coated between grooves and later technique can be conducted. By adding the auxiliary mark, the invention greatly reduces influence of CMP technique on nesting measurement and ensures accuracy of nesting measurement; therefore, the rate of finished product of the chip is increased.