A semiconductor substrate manufacturing method and a semiconductor substrate. The manufacturing method includes: forming a first semiconductor layer on the base substrate at a first temperature with a first oxide semiconductor material; forming the second semiconductor layer directly on the first semiconductor layer with a second oxide semiconductor material; and performing a patterning process such that the first semiconductor layer and the second semiconductor layer are respectively patterned into a seed layer and a first channel layer. Both the first oxide semiconductor material and the second oxide semiconductor material are capable of forming crystalline phases at a second temperature, the second temperature is less than or equal to 40° C., and the first temperature is greater than or equal to 100° C.