Post-cleaning method of a via etching process

Details Post-cleaning method of a via etching process Post-cleaning method of a via etching process

2001-04-11

2002-12-31

Whitehead, Jr., Carl (Department: 2822)

Semiconductor device manufacturing: process

Chemical etching

Vapor phase etching

C438S637000, C438S672000, C438S704000, C438S710000, C438S711000, C438S906000

Reexamination Certificate

active

06500766

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a cleaning method, in particular, the present invention relates to a post-cleaning method of a via etching process.
2. Description of the Related Art
In the semiconductor processing for pursuing the goal of minute line width and high integration, the product yield is greatly concerned with particles. In particular, during a via etching process, the residues remaining in the via will cause the electrical-connecting property between metal layers to deteriorate.
Please refer to FIG.
1
and FIG.
2
.
FIG. 1
is a cross-sectional schematic diagram of a via according to the prior art.
FIG. 2
is a flow chart of a post-cleaning method of a via etching process according to the prior art. A wafer
10
comprises a substrate
12
, a metal layer
14
formed on the substrate
12
, an oxide layer
16
covered on the metal layer
14
, and a photoresist layer
18
coated on the oxide layer
16
. By using a dry etching process, a via
20
is patterned to pass through the photoresist layer
18
and the oxide layer
16
till exposing a predetermined area of the metal layer
14
. In a post-cleaning method of the via etching process, the step
22
of a photoresist strip process is firstly performed to remove the photoresist layer
18
by a dry etching process in a plasma reactor, wherein the hydrocarbon inside the photoresist layer
18
is reacted with oxygen plasma to be stripped off and the produced gas, such as CO, CO
2
and H
2
O is pumped by a vacuum system. However, the photoresist strip process also produces polymer residues and which mostly remain in the via
20
. For this reason, the step
24
of a wet cleaning process is performed for cleaning off the polymer residues. In general, the wafer
10
is dipped into a sink filled with a specific etching solution, such as ACT, EKC or other alkaline compounds, on an appropriate condition of dipping time, temperature and solution concentration so as to make the polymer residues react with the etching solution to be removed off. Finally, at the step
26
of a water-rinsing process, the wafer
10
is turned vertically to ensure the fringe of the wafer
10
being cleaned off, and then the wafer
10
is dipped into deionized water to clean off the remaining etching solution.
Nevertheless, the wet cleaning method that utilizes the chemicals such as ACT and EKC with high waste volume encounters problems such as increasing cost of the chemicals and a shortage of chemical resources. It does not conform to expectations for the cost considerations of mass production. Also, since dipping the wafer
10
into the etching solution consumes a period time to make the polymer residues completely react with the etching solution, the overall via etching process period is increased.
SUMMARY OF THE INVENTION
Therefore, the present invention provides a post-cleaning method of a via etching process, which substitutes a dry cleaning process for the wet cleaning process to solve the above-mentioned problems.
A post-cleaning method of a via etching process for cleaning a wafer, the wafer comprising a tungsten (W) layer, an oxide layer covered on the tungsten layer, a photoresist layer patterned on the oxide layer, and a via passing through the photoresist layer and the oxide layer till exposing a predetermined area of the tungsten layer, the cleaning method comprises the steps of: (a) performing a photoresist strip process to remove the photoresist layer; (b) performing a dry cleaning process which uses CF
4
and N
2
H
2
as the main reactive gas; and (c) performing a water-rinsing process.
It is an advantage of the present invention that since the dry cleaning process substitutes the wet cleaning process to remove the polymer residues without using costly and rare alkaline compounds, the production cost is substantially decreased. Also, the dry cleaning process can quickly remove the polymer residues and the wafer needs not to be turned vertically before dipping into deionized water, so the overall post-clean process becomes more efficient. Furthermore, the photoresist strip process and the dry cleaning process can be performed in-situ; therefore this will facilitate the post-clean process.
This and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.


REFERENCES:
patent: 5756401 (1998-05-01), Iizuka
patent: 5795831 (1998-08-01), Nakayama et al.
patent: 5882489 (1999-03-01), Bersin et al.
patent: 6030901 (2000-02-01), Hopper
patent: 6180518 (2001-01-01), Layadi et al.
patent: 6277733 (2001-08-01), Smith

Affiliated with

Also associated with

Rating

Post-cleaning method of a via etching process does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Post-cleaning method of a via etching process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Post-cleaning method of a via etching process will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2998048