A deep trench filling method

Abstract

The invention discloses a deep trench filling method, in which deep grooves are filled with epitaxial layers until the epitaxial layers on the side walls of the trenches gather up at the bottom portions, and non-conductive mediums are used to fill the residual gaps in the trenches until the trenches are full. According to the deep trench filling method of the invention, the epitaxial filling is stopped after the bottom portions of the epitaxial layers gather up and before the top portions of the expixial layers gather up, and the epitaxial volumes of the bottom portions and the top portions of the epitaxial layers are kept to be approximate to each other. Since the impurity levels in the filling epitaxial layers are proportional to the volumes, the filling method can reduce the difference in the amount of impurities in the bottom and upper portions of the deep trenches and improve the uniformity of depletion regions so that the differences in the depletion degrees of the trenches at different depths are slight, thereby raising the overpressure resistant efficiency of the depletion regions and improving the overpressure resistant capability of products.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a deep trench filling method. Background technique [0002] For existing deep trench super junction products, the deep trench etching and epitaxial filling method is used to process the PN structure of the super junction products. However, the epitaxial filling rate of deep trench products is slow, and it takes a long time for epitaxial growth to completely fill the trenches, occupying the production capacity of epitaxial equipment, which is not conducive to mass production. [0003] The sidewall of the deep groove processing will have a certain angle, such as figure 1 As shown, the cross section of the groove is an inverted trapezoid, and the width of the edge of the groove is greater than the width of the bottom of the groove. The filling is done as figure 2 As shown, after epitaxial filling, the PN volume ratio at the top and bottom is inconsistent, that is, the ...

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Problems solved by technology

The filling is done as figure 2 As shown, after epitaxial filling, the PN volume ratio at the top and bottom is inconsistent, that is, the condition of the PN depletion region along the different depths of the deep trench changes. If the middle part of the trench is completely depleted, the upper part of the trench Holes will remain when depleted, and electrons will remain in the lower part of the trench when depleted, reducing the withstand voltage capability of the depleted region

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