Trench epitaxy filling method

Abstract

The invention discloses a trench epitaxy filling method. The method comprises: forming a hard mask layer formed by stacking a first oxide layer, a second nitration layer and a third oxide layer; carrying out first-time comprehensive ion implantation to destroy a molecular bond of the third oxide layer; carrying out photoetching to define a forming region of a trench; removing a hard mask layer inthe forming region of the trench; etching a semiconductor substrate to form a trench; carrying out a first-time wet etching process to remove the third oxide layer; forming a sacrificial oxide layer;carrying out second-time comprehensive ion implantation to destroy a molecular bond of the sacrificial oxide layer; carrying out second-time wet etching process to remove the sacrificial oxide layer;removing the second nitration layer; and carrying out epitaxial growth to form a trench epitaxy layer to fill the trench. Therefore, the horizontally etched amount of the first oxide layer is reduced;and occurrence of extending of the epitaxial layer between adjacent trenches out of the trench and combination generation can be prevented or reduced and thus the stress is eliminated or reduced anddislocation is avoided, so that the performances of the device are improved.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit manufacturing method, in particular to a trench epitaxy filling method. Background technique [0002] Such as Figure 1A to Figure 1G As shown, it is a schematic diagram of the device structure in each step of the filling method of the existing trench epitaxy; the epitaxial filling of the trench of the super junction structure is taken as an example for illustration, and the existing filling method of the trench epitaxy includes the following steps: [0003] Such as Figure 1A As shown, a semiconductor substrate such as a silicon substrate 101 is provided, an N-type epitaxial layer 102 is formed on the surface of the silicon substrate 101, and an oxide layer 103, a nitride layer 104 and an oxide layer are sequentially formed on the surface of the N-type epitaxial layer 102 105 and superimposed to form a hard mask layer; photolithography opens the formation area of ​​the trench, and sequential...

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Problems solved by technology

Since the epitaxial growth process is selected to grow on the surface of the epitaxial layer, and not to grow on the surface of the oxide layer, during the epitaxial growth process, the P-type epitaxial layer 106 will be formed on the side surface and bottom surface of the trench 201 and the undeveloped area outside the trench 201 at the same time. The surface of the N-type epitaxial layer 102 covered by the oxide layer 103 grows simultaneously, and the thickness of the P-type epitaxial layer 106 formed on the surface of the N-type epitaxial layer 102 not covered by the oxide layer 103 outside the trench 201 is greater than the thickness of the oxide layer 103. It will extend to the surface of the oxide layer 103 and grow laterally at the same time, finally making the P-type epitaxial layer 106 in the adjacent trenches 201 easily extend to each other on the surface of the oxide layer 103 between the trenches 201 to contact and merge to form an integral structure , the P-type epitaxial layer 106 formed on the oxide layer 103 and laterally contacting and merging with each other tends to generate stress and form dislocations (dislocation), which will eventually affect the performance of the device

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