Electron beam treatment of siloxane resins

Details Electron beam treatment of siloxane resins Electron beam treatment of siloxane resins

1999-01-06

2001-01-23

Seidleck, James J. (Department: 1711)

Coating processes

Direct application of electrical, magnetic, wave, or...

Polymerization of coating utilizing direct application of...

C427S510000, C427S516000, C427S508000, C522S099000, C522S148000, C522S172000, C528S031000, C438S099000

Reexamination Certificate

active

06177143

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cured siloxane dielectric films and to a process for their production by electron beam exposure. Such films are useful in the manufacture of integrated circuits (IC's).
2. Description of the Related Art
A continuing trend in the field of semiconductor technology is the formation of integrated circuit chips having more and faster circuits thereon. Such ultralarge scale integration has resulted in a continued shrinkage of feature sizes with the result that a large number of devices are available on a single chip. With a limited chip surface area, the interconnect density typically expands above the chip substrate in a multi-level arrangement and so the devices have to be interconnected across these multiple levels.
The interconnects must be electrically insulated from each other except where designed to make contact. Usually electrical insulation requires depositing dielectric films onto a surface. It is known in the art that siloxane resins are usefull in the electronic and semiconductor fields to provide a dielectric coating to silicon wafers and other components. Such coatings protect the surface of substrates and form dielectric layers between electric conductors on IC's. Such coatings can be used as protective layers, interlevel dielectric layers, doped dielectric layers to produce transistor like devices, capacitor and capacitor like devices, multilayer devices, 3-D devices, silicon on insulator devices, coatings for superconductors, and the like.
As mentioned above, semiconductor devices often have multiple arrays of patterned interconnect levels that serve to electrically couple individual circuit elements thus forming an integrated circuit. In the past, these interconnect levels have been separated by such insulating dielectric films as a silicon oxide film formed using chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD) techniques. However, as the size of circuit elements and the spaces between such elements decreases, the relatively high dielectric constant of such silicon oxide films has become a problem.
In order to provide a lower dielectric constant than that of silicon oxide, dielectric films formed from siloxane based resins are becoming widely used. The production of siloxane resins is well known in the art. In this regard, see U.S. Pat. Nos. 3,615,272; 4,756,977; 5,010,159 and 4,999,397. However, while such siloxane films do provide lower dielectric constants than CVD or PECVD silicon oxide films it has been found that typically the dielectric constants of such films are limited to approximately 3.0 or greater. The dielectric constant of such insulating films is an important factor where IC's with low power consumption, crosstalk, and signal delay are required. As IC dimensions continue to shrink, this factor increases in importance. As a result, siloxane based resin materials that can provide insulating films with dielectric constants below 3.0 are very desirable. In addition, it would be desirable to have a siloxane based resin which have a high resistance to cracking and low stress when formed in thicknesses of approximately 1.0 &mgr;m or greater. It has now been found that such crack resistant, low stress films can be produced when the particular organic siloxane resins of the present invention are cured using electron beam exposure.
Another problem with siloxane based resins is that they must be cured to be effective as a dielectric. Specifically, after a semiconductor wafer having metal lines is coated with the siloxane and cured, it must be resistant to oxygen plasmas in subsequent IC production operations. In the prior art, siloxane polymers have been thermally cured. Unfortunately, thermal curing leaves SiOH bonds in the siloxane polymer. When thermally cured siloxanes are then subjected to oxygen plasma, water is produced by the hydration of the SiOH bonds thus poisoning vias cut through the dielectric in a non-etchback process. It has now been unexpectedly found that electron beam curing changes the properties of the siloxane such that essentially no hydrogen remains after exposure. Thus water formation is avoided or significantly reduced. This results in a denser SiO-SiO structure, minimizing formation of a hydrated film and poisoned vias. In addition, electron beam exposure is much faster than thermal curing, thus increasing IC throughput.
SUMMARY OF THE INVENTION
The invention provides a process for forming a dielectric coating on a substrate which comprises
a) forming a dielectric composition film on a substrate, which dielectric composition comprises a polymer having a structure selected from the group consisting of I and II: I.
[H-SiO
1.5
]
n
[R-SiO
1.5
]
m
,
[H
0.5
-SiO
1.5-1.8
]
n
[R
0.5-1.0
-SiO
1.5-1.8
]
m
,
[H
0-1.0
-SiO
1.5
]
n
[R-SiO
1.5
]
m
,
[H-SiO
1.5
]
x
[R-SiO
1.5
]
y
[SiO
2
]
2
,
wherein the sum of n and m, or the sum or x, y and z is from about 8 to about 5000, and m and y are selected such that carbon containing substituents are present in an amount of less than about 40 Mole percent; II.
[HSiO
1.5
]
n
[RSiO
1.5
]
m
,
[H
0.5-1.0
SiO
1.5-1.8
]
n
[R
0.5-1.0
SiO
1.5-1.8
]
m
,
[H
0.5-1.0
SiO
1.5-2.0
][RSiO
1.5
]
m
,
wherein the sum of n and m is from about 8 to about 5000 and m is selected such that the carbon containing substituent is present in an amount of from about 40 Mole percent or greater; and
[HSiO
1.5
]
x
[RSiO
1.5
]
y
[SiO
2
]
x
;
wherein the sum of x, y and z is from about 8 to about 5000 and y is selected such that the carbon containing substituent is present in an amount of about 40 Mole % or greater; and wherein R is selected from substituted and unsubstituted straight chain and branched alkyl groups, cycloalkyl groups, substituted and unsubstituted aryl groups, and mixtures thereof;
b) optionally contacting the film with a surface modification composition;
c) optionally heating the film to evaporate solvents from the film;
d) exposing the film to electron beam radiation; and
e) optionally thermally annealing the exposed film.
The invention also provides a semiconductor device produced by the above process wherein the substrate is a semiconductor substrate.
DETAILED DESCRIPTION OF THE INVENTION
The first step in conducting the process of the present invention is to form a dielectric composition on a film which comprises one or more polymers having a structure I or II. Polymers having the structure I are of low organic content where the carbon containing substituents are present in an amount of less than about 40 mole percent. These polymers are described more filly in U.S. patent application Ser. No. 09/044,831, filed Mar. 20, 1998, which is incorporated herein by reference.
In accordance with the present invention, siloxane polymers having the structure I have the formulae:
[H-SiO
1.5
]
n
[R-SiO
1.5
m
,
[H0.5-SiO
1.5-1.8
]
n
[R
0.5-1.0
-SiO
1.5-1.8
]
m
,
[H
0.1-0
-SiO
1.5
]
n
[R-SiO
1.5
]
m
,
[H-SiO
1.5
]
x
[R-SiO
1.5
]
y
[SiO
2
]
x
,
wherein the sum of n and m, or the sum or x, y and z is from about 8 to about 5000, and m and y are selected such that carbon containing substituents are present in an amount of less than about 40 mole percent. R, is selected from substituted and unsubstituted straight chain and branched alkyl groups, cycloalkyl groups, substituted and unsubstituted aryl groups, and mixtures thereof The specific mole percent of carbon containing substituents is a function of the ratio of the amounts of starting materials. In a preferred embodiments the mole percent of carbon containing substituents is in the range of from about 15 mole percent to about 25 mole percent.
In another embodiment of the invention, one may use polymers having the structure II which are of high organic content where the carbon containing substituents are p

Affiliated with

Also associated with

Rating

Electron beam treatment of siloxane resins does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electron beam treatment of siloxane resins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electron beam treatment of siloxane resins will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2445893