Method of cleaning a dual damascene structure

Details Method of cleaning a dual damascene structure Method of cleaning a dual damascene structure

2001-02-20

2003-10-21

Zarabian, Amir (Department: 2822)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S622000, C438S638000, C438S629000, C438S672000, C438S675000, C438S687000

Reexamination Certificate

active

06635565

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor cleaning method. More particularly, the present invention relates to a method of cleaning a dual damascene structure.
2. Description of the Related Art
A multiple interconnection process employs dual damascene structures. Thus, the reliability of the devices is increased. In addition, the process window is also increased. As the integration of the integrated circuit increases, dual damascene technology has become a main technology in the semiconductor industry.
In a Very Large Scale Integrated (VLSI) semiconductor process, a cleaning step performed in each fabrication stage is an important factor for obtaining high-quality devices. The wafer pollution includes particulates and film contaminates. Any particle that appears on the chip surface is called a particulate, which can come from the operation workers or the operation machines, such as the quartz pipes of a high-temperature furnace, a polished film or photoresist particles, and even the particles or bacteria from the deionized wafer. In addition, the film contamination is caused by a layer of contaminates that come from the outside deposited on the wafer. The layer of contaminates that come from outside include solvent residues, the residues of the developing solvent, etc.
FIG. 1A
is a schematic, cross-sectional view showing a substrate after forming and cleaning a dual damascene opening in a conventional dual damascene process.
In
FIG. 1A
, a substrate
100
has a copper layer
102
therein. A dielectric layer
104
is formed over the substrate
100
. A dual damascene opening
120
is formed in the dielectric layer
104
. Usually, after the dual damascene opening
120
is formed, a cleaning step is performed with a dilute hydrogen fluoride (HF) solution. However, polymer residues
108
cannot be completely removed after the cleaning step is performed. In addition, the HF cleaning solution overly corrodes the copper layer
102
, and thus resulting in a recess surface in the copper layer
102
.
FIG. 1B
is a schematic, cross-sectional view showing a substrate after performing a chemical mechanical polishing and a cleaning step in the conventional dual damascene process.
In
FIG. 1B
, a copper layer (not shown) is formed over the substrate
100
to fill the dual damascene opening
120
. A chemical mechanical polishing (CMP) step is performed to remove the copper layer on the outside of the dual damascene opening
120
. A dual damascene structure
122
thus is formed. Thereafter, a cleaning step is performed using an amine-containing solution, such as an ESC780 solution. However, as shown in
FIG. 1B
, hydrocarbon particulates
109
, which are generated from the reaction between the dielectric layer
104
and the CMP slurry, and slurry residues
110
still remain on the surface of the dual damascene structure
122
after the cleaning step is performed.
Therefore, the disadvantage of the conventional method is that the polymer residues cannot be completely removed by the HF solution. In addition, the cleaning step performed after the CMP step cannot remove the hydrocarbon particles and the slurry residues. This, in turn, causes a rough surface forming in a wafer. Consequently, a subsequent photolithography process fails.
SUMMARY OF THE INVENTION
The invention provides a method of cleaning a dual damascene structure. A first conductive layer is formed in a substrate. A dielectric layer is formed over the substrate. A dual damascene opening is formed in the dielectric layer to expose the first conductive layer. A H
2
O
2
based aqueous solution is used to remove polymer residues in the dual damascene opening. A temperature of the H
2
O
2
based aqueous solution is controlled so that the first conductive layer is not corroded. A diluted HF solution or a diluted HF and HCl solution is used to remove the polymer residues. A second conductive layer is formed over the substrate to fill the dual damascene opening. A chemical mechanical polishing process is performed with the dielectric layer serving as a polishing stop to remove the second conductive layer outside the dual damascene opening. A H
2
O
2
based aqueous solution is used to clean the hydrocarbon particulates from the chemical mechanically polishing step. A diluted HF solution or a diluted HF and HCl solution is used to remove the slurry residues, such as silicon oxide of the slurry, from the chemical mechanical polishing step.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.


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Miyamato et al. “Wet Chemical Cleaning for Damged Layer Removal Inside theDeep Sub-micron Contact Hole”, IEEE, pp. 327-331.

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