Air gap semiconductor structure and method of manufacture

Details Air gap semiconductor structure and method of manufacture Air gap semiconductor structure and method of manufacture

2000-12-29

2001-11-13

Elms, Richard (Department: 2824)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S780000, C438S781000, C438S421000, C438S422000

Reexamination Certificate

active

06316347

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 89127061, filed Dec. 18, 2000.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a metal-oxide-semiconductor structure and corresponding method of manufacture. More particularly, the present invention relates to an air gap semiconductor structure and corresponding method of manufacture.
2. Description of Related Art
Following the rapid reduction of semiconductor line width, the accompanied increase in resistor-capacitor (RC) time delay has greatly reduced the operating speed of integrated circuits. To reduce RC time delay, methods that can lower resistance is frequently adopted. The most common trend now is to replace conventional aluminum wires by copper wires.
A second way of reducing RC time delay is to reduce capacitance between conductive wires in a multi-layer design. Conventional silicon dioxide is no longer versatile enough for this purpose because silicon dioxide has a relatively high dielectric constant. In general, low dielectric constant organic or inorganic material is used to form inter-metal dielectric layers. However, a medium having the lowest dielectric constant is air (a dielectric constant of 1). Therefore, air is an ideal dielectric medium for lowering the capacitance of a capacitor.
Although air is the best dielectric material for lowering capacitance, overall mechanical strength of the device is reduced correspondingly. A weakened structure can have serious effects in various aspects of subsequent integrated circuit fabrication.
FIG. 1
is a schematic cross-sectional view showing a conventional semiconductor device that uses air as a dielectric medium. As shown in
FIG. 1
, the structure includes a metallic line
102
over a substrate
100
. A silicon dioxide layer
104
is attached to the upper surface of the metallic line
102
, thereby forming air pockets
106
and
108
that also serve as a dielectric layer.
In the aforementioned implementation, the metallic lines
102
are usually separated from each other by a distance. Air pockets such as
108
may destabilize the semiconductor structure leading to ultimate deformation. Moreover, the air pockets
106
and
108
are normally distributed all over the substrate
100
. Although capacitors have low capacitance when air is used as a dielectric medium layer, the poor heat conductivity of air often results in a rapid rise in temperature during operation.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an air gap semiconductor structure and corresponding method of manufacture. The method includes providing a substrate having metallic lines thereon. A high molecular weight sacrificial film is formed over the substrate. A portion of the high molecular weight sacrificial layer is removed to form spacers. A dielectric layer is formed over the substrate, the top surface of the metallic lines and the spacers. Finally, a thermal dissociation operation is conducted to remove the spacers, thereby forming an air pocket on each sidewall of the metallic lines.
In this invention, the air gaps in this invention only form on the sidewall of the metallic lines. Conventional dielectric material fills the other portions of the substrate. With this arrangement, resistor-capacitor delay is reduced and operating speed of the integrated circuit is increased. Yet, the substrate has sufficient mechanical strength to support other structures.
In addition, because only spacer-like air gaps are formed on the sidewalls of the metallic lines, heat generated by the device can easily be conducted away to the surroundings. Hence, heat dissipation problem is minimized.
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.


REFERENCES:
patent: 6165890 (2000-12-01), Kohl et al.

Affiliated with

Also associated with

Rating

Air gap semiconductor structure and method of manufacture does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Air gap semiconductor structure and method of manufacture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Air gap semiconductor structure and method of manufacture will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2603901