Substrate transfer method

The invention provides a substrate transfer method, which includes defining a plurality of substrates stored in a substrate storage area as working substrates and temporary storage substrates. A robotic arm takes out one of the working substrates from the substrate storage area, transfers the working substrate to an alignment unit for alignment, and transfers the aligned working substrate to a load-lock chamber. The robotic arm takes out one of the temporary storage substrates from the substrate storage area, transfers the temporary storage substrate to the alignment unit for alignment, and transfers the aligned temporary storage substrate to a nitrogen buffer chamber. The method of the present invention can avoid forming an oxide layer on the temporary storage substrate, or prevent the photoresist disposed on the temporary storage substrate from absorbing water and deforming, thereby affecting the precision of the line width and line spacing defined by the photoresist.