Filling method for groove epitaxial layers

Abstract

The invention discloses a filling method of groove epitaxial layers. The filling method comprises the following steps: forming a hard mask layer superimposed by a first oxidation layer, a second nitridation layer and a third oxidation layer; photoetching to define a forming area of the grooves and etching the hard mask layer; carrying out etching on a semiconductor substrate to form the grooves bytaking the hard mask layer as a mask; adopting a wet etching technology to remove the third oxidation layer; forming a sacrificed oxidation layer and carrying out wet removal; and carrying out epitaxial growth to from the grooves filled with the groove epitaxial layers. By using the characteristic that the second nitridation layer is not etched in the process of removing the third oxidation layerand the sacrificed oxidation layer, the top of the semiconductor substrate between the grooves is covered with the second nitridation layer, and the groove epitaxial layers of every two adjacent grooves are prevented from extending to the surface of the second nitridation layer and are merged with each other, so that the stress of the groove epitaxial layers is reduced, the dislocation generatedby the stress can be avoided, and the performance of the device is 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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