Double-sided cathode spiral ring gradual change type silicon drift detector and preparation method thereof

The invention discloses a double-sided cathode spiral ring gradual change type silicon drift detector and a preparation method thereof; the front surface of a gradual change type detector unit and theback surface of the gradual change type detector unit are positioned on two opposite planes of a high resistance silicon substrate; the front surface of the gradual change type detector unit comprises a first gradual change type P+ cathode spiral ring and an N+ collection anode embedded in the first gradual change type P+ cathode spiral ring, wherein the first gradual change type P+ cathode spiral ring is composed of a front circular region, a front gradual change region and a front square region; the back surface of the gradual change type detector unit comprises a second gradual change typeP+ cathode spiral ring, wherein the second gradual change type P+ cathode spiral ring is composed of a back circular area, a back surface gradual change region and a back surface square region; and amiddle electrode is arranged in the center of the second gradient type P+ cathode spiral ring. A silicon dioxide layer is generated on the surface of the N-type high-resistance silicon wafer througha gettering oxidation process, and the detector pattern is transferred to a silicon dioxide layer, and then etching and ion implantation and activation on each part are carried out; and finally the damage of the detector is repaired.