Super-junction structure and method for manufacturing same

A method for manufacturing a super-junction structure, comprising the following steps:

• Step 1, providing a semiconductor substrate formed with an N-type epitaxial layer on a surface and defining formation areas of the super-junction trenches by photolithography process;
• Step 2, carrying out primary etching according to the photolithography process definition to form top trenches in the N-type epitaxial layer, wherein a side angle of each said top trench is smaller than 90°, a width of a bottom surface of each said top trench is smaller than that of a top surface of the top trench, each said top trench has a trapezoidal section, and the side angle of each said top trench is an apex angle of the trapezoidal section of the top trench;
• Step 3, carrying out secondary etching to form bottom trenches in portions, at bottoms of the top trenches, of the N-type epitaxial layer, and stacking the bottom trenches and the top trenches together to form the super junction trenches;
• wherein, a side angle of each said bottom trench is greater than 90°, a width of a bottom surface of each said bottom trench is greater than that of a top surface of the bottom trench, the bottom surface of each said top trench is the top surface of the corresponding bottom trench;
• each said bottom trench has a trapezoidal section, and the side angle of each said bottom trench is an apex angle of the trapezoidal section of the bottom trench;
• and
• Step 4, filling the super-junction structures with P-type materials, wherein P-pillars are formed by the P-type materials filled in the super-junction trenches, N-pillars are formed by portions, between the P-pillars, of the N-type epitaxial layer, and the N-pillars and the P-pillars are alternately arrayed to form a super-junction structure;
• wherein, the whole super-junction trenches are each of a waisted structure, and the bottom trenches increase a bottom width of the super-junction trenches and improve the depletion of bottoms of the N-pillars, thus, increasing the breakdown voltage of the super-junction structure.

A method for manufacturing a super-junction structure, comprising the following steps:

• Step 1, providing a semiconductor substrate formed with a first N-type epitaxial layer on a surface and defining formation areas of the super-junction trenches by photolithography process;
• Step 2, carrying out secondary etching according to the photolithography process definition to form bottom trenches in the first N-type epitaxial layer, wherein a side angle of each said bottom trench is greater than 90°, a width of each said bottom trench is greater than that of a top surface of the bottom trench, each said bottom trench has a trapezoidal section, and the side angle of each said bottom trench is an apex angle of the trapezoidal section of the bottom trench;
• Step 3, filling the bottom trenches with P-type materials;
• Step 4, forming a second N-type epitaxial layer through epitaxial growth on a surface of the first N-type epitaxial layer, and stacking the first N-type epitaxial layer and the second N-type epitaxial layer together to form an N-type epitaxial layer;
• Step 5, carrying out primary etching according to the photolithography process's definition to form top trenches in the second N-type epitaxial layer, wherein a side angle of each said top trench is smaller than 90°, a width of a bottom surface of each said top trench is smaller than that of a top surface of the top trench, each said top trench has a trapezoidal section, and the side angle of each said top trench is an apex angle of the trapezoidal section of the top trench;
• wherein, the bottom surface of each said top trench is the top surface of the corresponding bottom trench, and the bottom trenches and the top trenches are stacked to form the super-junction trenches;
• and
• Step 6, filling the top trenches with P-type materials, wherein P-pillars are formed by the P-type materials filled in the super-junction trenches, N-pillars are formed by portions, between the P-pillars, of the N-type epitaxial layer, and the N-pillars and the P-pillars are alternately arrayed to form a super-junction structure;
• wherein, the whole super-junction trenches are each of a waisted structure, and the bottom trenches increase a bottom width of the super-junction trenches and improve the depletion of bottoms of the N-pillars, thus, increasing the breakdown voltage of the super-junction structure.