Pseudo buried layer and manufacturing method of the same, deep hole contact and bipolar transistor

A pseudo buried layer, which is formed at the bottom of a shallow trench in a silicon substrate, comprising a phosphorus impurity region and an arsenic impurity region;

• wherein, the phosphorus impurity region has a larger coverage area than the arsenic impurity region;
• the arsenic impurity region is formed at the bottom of the shallow trench;
• the phosphorus impurity region extends laterally into an active region and vertically into the silicon substrate away from the bottom of the shallow trench;
• and the concentration of the arsenic impurity region is larger than that of the phosphorus impurity region.

A deep hole contact, comprising a metal formed in a deep hole and contacting with a pseudo buried layer, wherein, the deep hole is formed in a shallow trench field oxide on the top of the pseudo buried layer;

• the pseudo buried layer is formed at the bottom of a shallow trench in a silicon substrate and comprises a phosphorus impurity region and an arsenic impurity region;
• the phosphorus impurity region has a larger coverage area than the arsenic impurity region;
• the arsenic impurity region is formed at the bottom of the shallow trench;
• the phosphorus impurity region extends laterally into an active region and vertically into the silicon substrate away from the bottom of the shallow trench;
• the concentration of the arsenic impurity region is larger than that of the phosphorus impurity region;
• an ohmic contact is formed between the metal in the deep hole and the arsenic impurity region.

A bipolar transistor, whose N-type region is formed in an active region in a silicon substrate and connects to pseudo buried layers and is picked up through deep hole contacts, wherein, the pseudo buried layers are formed in the silicon substrate at the bottom of shallow trenches adjacent to the active region and each comprises a phosphorus impurity region and an arsenic impurity region;

• the coverage area of the phosphorus impurity region is larger than that of the arsenic impurity region;
• the arsenic impurity region is formed at the bottom of the respective shallow trench;
• the phosphorus impurity region extends laterally into the active region and vertically into the silicon substrate away from the bottom of the respective shallow trench;
• the concentration of the arsenic impurity region is larger than that of the phosphorus impurity region;
• the N-type region is connected with the phosphorus impurity regions;
• each of the deep hole contacts comprises a metal in a deep hole formed in a shallow trench isolation on the top of the respective pseudo buried layer, the metal in the deep hole contacts with the respective pseudo buried layer, and the metal forms an ohmic contact with the respective arsenic impurity region.