Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-05-14
2003-09-23
Cao, Phat X. (Department: 2814)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S623000, C438S624000, C438S625000, C438S618000, C438S637000
Reexamination Certificate
active
06624061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device having a low dielectric constant film, and a method of manufacturing a semiconductor device with the low dielectric constant film. More specially, the present invention relates to a semiconductor device having a through hole and/or a groove (trench) while reducing deterioration of a low dielectric constant film in the manufacturing stage, and also to a method for manufacturing the semiconductor device having a low dielectric constant film. The through hole is employed to connect electrically wiring lines/patterns formed on and under the low dielectric constant film respectively. The groove is used to embed or bury the wiring lines/patterns into the low dielectric constant film.
2. Description of the Related Art
In general, electronic devices with using semiconductors require high-speed operations. More specifically, high-speed operation requirements are highly emphasized in logic devices.
Conventionally, as methods capable of operating semiconductor devices in high speeds, operating speeds of transistors are increased. On the other hand, while semiconductor devices are manufactured by realizing very fine structures, delays occurred in signals propagated through wiring lines/patterns would cause a serious problem, rather than delays occurred in signals due to parasitic capacitances of transistors.
In general, lengths of wiring lines employed in logic devices are made long. Under such a circumstance, it is usually required to suppress delays of signals propagated through wiring lines.
A speed of a signal propagated through a wiring line may be defined by multiplying a wiring line resistance (R) by a capacitance between wiring lines (C), namely a product (R×C). When the value of this product (R×C) is small, the speed of the signal propagated through the wiring line becomes fast, whereas when the value of this product (R×C) is large, the speed of the signal propagated through the wiring line becomes delay.
To suppress a delay contained in a signal propagation speed, al least one of a wiring line resistance (R) and a capacitance (C) between wiring lines is required to be reduced. Conventionally, aluminum wiring lines have been employed to reduce wiring resistances (R). Recently, copper wiring lines having a lower resistance than that of aluminum wiring lines are examined to be used for the same purpose. On the other hand, conventionally, silicon oxide films and silicon nitride films are examined to be employed to form interlayer films for reducing capacitance (C) between wiring lines. Recently, various sorts of low dielectric constant films are examined to be used. These low dielectric constant films are made of either organic materials or inorganic materials, the dielectric constant of which is lower than that of the silicon oxide film, or silicon nitride film.
Very recently, as the low dielectric constant films capable of reducing the capacitance (C) between wiring lines, an HSQ (hydrogen silsesquioxane) film corresponding to an inorganic coating film is desirably employed.
When a low dielectric constant film is formed in a semiconductor device having a multi-layer wiring structure, a plug is necessarily formed to connect wiring lines (patterns) electrically formed on an upper layer and a lower layer of this low dielectric constant film. To this end, a through hole must be formed in the low dielectric constant film.
FIGS. 1A
,
1
B, and
1
C are section views of schematically indicating one conventional forming step for forming a through hole in a low dielectric constant film.
First, as shown in
FIG. 1A
, a silicon oxide film
302
is formed on a semiconductor substrate
301
. Subsequently, a silicon nitride film
303
is formed on this silicon oxide film. Next, an aluminum wiring line (pattern)
304
functioning as a lower-layer (under-layer) wiring line is formed in a groove (trench) which is formed in both the silicon oxide film
302
and the silicon nitride film
303
. Thereafter, an HSQ (hydrogen silsesquioxane) film
305
functioning as an interlayer insulating film is formed on the entire portions of the silicon nitride film
303
and the aluminum wiring line
304
. Next, a resist mask
306
is formed on this HSQ film
305
. A dry etching treatment with this resist mask
306
is carried out for the HSQ film
305
to form a through hole
315
in this HSQ film
305
. At this time, the over etching treatment is sufficiently performed to expose completely the aluminum wiring line
304
formed on the bottom portion of the through hole
315
. As a result of the above manufacturing steps, the semiconductor structure shown as the section view of
FIG. 1A
is obtained.
There are many possibilities that the over-etched amount obtained by the above-described over-etching treatment becomes more than, or equal to 100 percents. At this time, a large number of deposited articles
311
made of aluminum compound are formed inside the through hole
315
. This condition is illustratively shown as the section view of FIG.
1
B.
Next, the resist mask
306
is stripped by employing oxygen plasma. Also, the deposited articles
311
formed inside the through hole
315
are removed by using organic solvent. Usually, the following organic solvent used in this removing process operation is used to remove the deposited articles
311
without melting metal aluminum, that is to say, solvent containing amine such as hidroxylamine. Thereafter, a conductive material made of copper is embedded within this through hole
315
to form a plug
307
. As a result of the above manufacturing steps, the semiconductor structure shown as the section view of
FIG. 1C
is obtained.
The silicon nitride film
303
formed on the lower layer of the HSQ film
305
may function as the etching stopper to the silicon oxide film
302
formed on the lower layer when a misalignment is produced to the aluminum wiring line
304
in the step of forming the through hole
315
. As a result, the silicon nitride film
303
can be used to prevent the silicon oxide film
302
from being etched away.
Although the above-described manufacturing steps are directed to forming of the plug
307
in the HSQ film
305
, similar manufacturing steps may be applied when the groove wiring line is formed in the HSQ film
305
. In particular, when the wiring line is made of copper, since the dry etching treatment can be hardly executed for the copper film, this groove wiring line may be used.
This HSQ film
305
is readily deteriorated in the case that this HSQ film
305
is reacted with the oxygen plasma or the organic solvent. Also as indicated in the above-explained manufacturing steps, the resist mask
306
is stripped by using the oxygen plasma, and the deposited articles
311
formed inside the through hole
315
are removed by using the organic solvent. While the above-described stripping process operation as well as removing process operation is carried out, since both the oxygen plasma and the organic solvent may give adverse influences to the surface of the HSQ film
305
. As a result, an HSQ damaged portion
312
is produced on this surface of the HSQ film
305
, and this HSQ film
305
would be deteriorated.
A concrete explanation will now be made of deterioration reaction of the above-explained HSQ film
305
.
First, an HSQ film owns an Si—H coupling. This Si—H coupling is changed into an Si—OH coupling when the HSQ film reacts with oxygen plasma and organic solvent. As a result, the HSQ film will be changed into such a film having a moisture absorption characteristic. In such a case that the HSQ film contains water, a leak amount of a current in the plug
307
and the groove wiring line will be increased, and also a dielectric constant owned by this HSQ film is increased. Furthermore, since the HSQ film can readily absorb water, this water may corrode the metal copper and the metal aluminum, which are made in contact with this HSQ film. As a result, there are possibilities that the circuit performance would be l
Cao Phat X.
Le Thao X.
NEC Electronics Corporation
Scully Scott Murphy & Presser
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