Percent backsputtering as a control parameter for metallization

Details Percent backsputtering as a control parameter for metallization Percent backsputtering as a control parameter for metallization

2000-09-21

2002-11-05

Oda, Christine K. (Department: 2858)

Electricity: measuring and testing

Impedance, admittance or other quantities representative of...

Lumped type parameters

C324S719000, C324S765010, C438S761000, C438S762000, C438S763000

Reexamination Certificate

active

06476623

ABSTRACT:

FIELD OF THE INVENTION
The present invention is related to the field of semiconductor fabrication and more particularly to a method of monitoring and controlling metallization using percent backsputtering as a control parameter to achieve low contact resistance and interface void-free metal layer.
RELATED ART
In the field of semiconductor fabrication, the use of copper metallization for high speed semiconductor devices is becoming increasingly prevalent. In a typical copper metallization process, a barrier layer is deposited over an underlying first copper layer using a physical vapor deposition (PVD) process. Referring to
FIG. 1
, a diagram of a metal sputtering tool
100
(also referred to herein as metal sputtering chamber
100
) is presented.
In the depicted embodiment, sputtering tool
100
includes a chassis
102
that defines a chamber
101
and encloses a sputter target
104
that is comprised at least partially of a material to be deposited on a wafer surface. Sputter target
104
may include tantalum, tantalum nitride, titanium, titanium nitride, copper, or other metal elements suitable for use in a semiconductor interconnect structure.
The depicted embodiment of sputtering tool
100
is characteristic of commercially distributed ionized metal plasma deposition tools such as the Endura® line of sputtering tools from Applied Materials, Inc. A DC power supply
106
provides a bias to sputtering target
104
while a rotating magnetic assembly
116
provides a magnetic field within chamber
101
of sputtering tool
100
. In addition, a radio frequency (RF) power supply
108
energizes a coil
109
within chamber
101
. A platform
112
within chamber
101
is connected to an AC power supply
110
. In one embodiment, RF power supply
108
operates at a frequency of approximately 2 MHz and an AC power supply
110
operates at a frequency of approximately 13.56 MHz.
As depicted in
FIG. 1
, a wafer
120
is placed within chamber
101
. In one embodiment, wafer
120
is displaced above pedestal
112
by one or more electrically insulating buttons
114
typically comprised of a ceramic material. In other embodiments, wafer
120
may rest directly upon platform
112
.
In the depicted embodiment, a gas inlet
116
provides means for introducing one or more source gases
118
into chamber
101
during deposition. Suitable source gasses
118
may include inert species such as argon, xenon, or helium as well as other source gases including nitrogen.
As an inert species such as argon is released into chamber
101
, RF power source
108
generates a plasma that includes charged argon particles which are attracted to the target
104
by DC bias
106
. As the relatively heavy argon particles strike target
104
, target particles are released into chamber
101
where a certain percentage of the particles are charged in the plasma generated by RF source
108
. These charged particles (as well as a certain percentage of uncharged target particles) traverse chamber
101
and are deposited on wafer
120
.
The power used for DC power supply
106
and RF power supply
108
are typically in excess of 1000 W and can result in the generation of highly energetic particles. In addition, the plasma itself is generally sustained at a temperature of approximately 300° C. The combination of the highly energetic particles and plasma thermal energy can result in significant localized heating of the wafer where the sputter material is deposited. In the case of sputter depositing a barrier material such as tantalum over a metal such as copper, it is theorized that the localized heating may result in recrystallization of the copper or thermal expansion and subsequent contraction of the copper thereby resulting in the formation of voids beneath the tantalum layer.
Attempts at correlating the occurrence of such voids to conventional parameters such as the AC power applied during tantalum deposition have been generally unsuccessful in eliminating the formation of voids. It would therefore be desirable to correlate the occurrence of voids during a biased metallization process to a quantifiable parameter and to implement a method of characterizing and qualifying a sputtering tool
100
based on the determined parameter. It would be further desirable if implemented solution did not significantly increase the cost and complexity of the metallization process.


REFERENCES:
patent: 3926747 (1975-12-01), Newby et al.
patent: 4886765 (1989-12-01), Chen et al.
patent: 4933304 (1990-06-01), Chen et al.
patent: 5421976 (1995-06-01), Holmquist
patent: 5675310 (1997-10-01), Wojnarowski et al.
patent: 5737177 (1998-04-01), Mett et al.
patent: 5812361 (1998-09-01), Jones et al.
patent: 5942889 (1999-08-01), Loewenhardt et al.
patent: 5989349 (1999-11-01), Ke et al.
patent: 6258466 (2000-01-01), McTeer
patent: 6169027 (2001-01-01), Dobson
patent: 6193855 (2001-02-01), Gopalraja et al.
patent: 6200911 (2001-03-01), Narwqankar et al.

Affiliated with

Also associated with

Rating

Percent backsputtering as a control parameter for metallization does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Percent backsputtering as a control parameter for metallization, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Percent backsputtering as a control parameter for metallization will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2927218