Taiwan Semiconductor Manufacturing Comp. Ltd.

L C Chen

Mei-Yen Li

Y J Mii

M Y Li

The present invention discloses a method for forming a DRAM capacitor that has improved charge capacitance which can be carried out by first depositing an oxide layer on a semiconducting substrate, forming an uneven surface on the oxide layer, forming a capacitor node in the oxide layer to expose the substrate, depositing a polysilicon layer on top of the oxide layer and in the node such that the uneven surface on the oxide layer is substantially reproduced in a top surface of the polysilicon layer, depositing a dielectric layer and a second polysilicon layer sequentially on top of the first polysilicon layer to reproduce the uneven surface on the oxide layer, and then defining the DRAM capacitor.

Method for forming a DRAM capacitor having improved capacitance and

The present invention discloses a method for forming a DRAM capacitor that has improved charge capacity and a DRAM capacitor formed by such method. The method can be carried out by first depositing an oxide layer on a lower polysilicon electrode layer on a semiconductor structure, then polishing the top surface of the oxide layer to form an uneven surface which provides increased surface area, and then anisotropically etching away the oxide layer while reproducing the uneven surface of the oxide layer onto the lower polysilicon electrode layer such that an increased charge capacity can be realized. The anisotropic etch chemistry should be selected such that the etchant etches away both the oxide layer and the polysilicon layer, and preferably, the etchant should have a higher selectivity toward polysilicon and a lower selectivity toward oxide such that the oxide layer can be completely removed while only a portion of the polysilicon layer is removed to form the uneven surface.

Method for improving capacitance in DRAM capacitors and devices formed

The present invention discloses a method for increasing capacitance in DRAM capacitors by the operating steps of first providing a cavity in a semiconductor substrate, then depositing a first polysilicon layer in the cavity, and a metal layer on top of the polysilicon layer to form a silicide layer. The semiconductor substrate is then heat treated in a rapid thermal processing method so that the metal silicide layer forms an island structure on top of the first polysilicon layer. The first polysilicon layer can then be isotropically etched by using the metal silicide island structure as a mask to form an island structure in the first polysilicon layer. Additional dielectric layer and polysilicon layers are then deposited to form the insulating layer and the upper electrode for the capacitor. The increased surface area, i.e., approximately two times, of the lower electrode polysilicon layer greatly increases its storage area for the capacitor and therefore greatly improves its capacitance.

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Hsin-Chu, Taiwan

L C Chen