Thermosetting anti-reflective coatings for full-fill dual...

Details Thermosetting anti-reflective coatings for full-fill dual... Thermosetting anti-reflective coatings for full-fill dual...

2001-01-08

2002-09-03

Dawson, Robert (Department: 1712)

Stock material or miscellaneous articles

Composite

Of epoxy ether

C430S271100, C430S935000, C523S436000, C525S510000, C525S514000, C525S523000, C525S533000

Reexamination Certificate

active

06444320

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is concerned with new polymers which can be used to form new anti-reflective or fill compositions for use in the manufacture of microelectronic devices. The polymers comprise an alicyclic moiety, with this moiety preferably forming the backbone of the polymer.
2. Description of the Prior Art
The damascene process, or the process of forming inlaid metal patterning in preformed grooves, is generally a preferred method of fabricating interconnections for integrated circuits. In its simplest form, the dual damascene process starts with an insulating layer which is first formed on a substrate and then planarized. Horizontal trenches and vertical holes (i.e., the contact and via holes) are then etched into the insulating layer corresponding to the required metal line pattern and hole locations, respectively, that will descend down through the insulating layer to the device regions (if through the first insulating layer, i.e., a contact hole) or to the next metal layer down (if through an upper insulating layer in the substrate structure, i.e., a via hole). Metal is next deposited over the substrate thereby filling the trenches and the holes, and thus forming the metal lines and the interconnect holes simultaneously. As a final step, the resulting surface is planarized using the known chemical-mechanical polish (CMP) technique, and readied to accept another dual damascene structure.
During the dual damascene process, the contact and via holes are typically etched to completion prior to the trench etching. Thus, the step of trench etching exposes the bottom and sidewalls (which are formed of the insulating or dielectric layer) of the contact or via holes to over-etch which can deteriorate the contact with the base layer. An organic material is therefore used to partially or completely fill the via or contact holes and to protect the bottom and sidewalls from further etch attack. These organic fill materials can also serve as a bottom anti-reflective coating to reduce or eliminate pattern degradation and linewidth variation in the patterning of the trench layer, provided the fill material covers the surface of the dielectric layer.
Fill materials have been used for the past several years which have high optical density at the typical exposure wavelengths. However, most prior art materials have limited fill properties. For example, when the prior art compositions are applied to the via or contact holes formed within the substrate and to the substrate surface, the films formed by the compositions tend to be quite thin on the substrate surface immediately adjacent the holes, thus leading to undesirable light reflection during subsequent exposure steps. Also, because the prior art compositions etch more slowly than the dielectric layer, the unetched fill compositions provide a wall on which the etch polymer will deposit. This etch polymer build-up then creates undesirable resistance within the metal interconnects of the final circuit.
There is a need in the art for contact or via hole fill materials which provide complete coverage at the top of via and contact holes. Furthermore, this material should provide adequate protection to the base of the via and contact holes during etching to prevent degradation of the barrier layer and damage to the underlying metal conductors.
SUMMARY Of THE INVENTION
The present invention is broadly concerned with new polymers for use in preparing anti-reflective or fill compositions and methods of using those compositions to protect substrates, and particularly contact and via holes formed therein, during circuit manufacturing.
In more detail, the polymers comprise a moiety according to the formula
wherein R comprises a light attenuating compound. Preferred light attenuating compounds are those selected from the group consisting of
wherein each X is individually selected from the group consisting of hydrogen, —OR
1
, —N(R
1
)
2
, and —SR
1
, and each R
1
is individually selected from the group consisting of hydrogen and branched and unbranched alkyl groups (preferably C
1
-C
20
, and more preferably C
1
-C
10
).
Preferably, the polymer further comprises monomers according to the formulas
wherein each Y is individually selected from the group consisting of hydrogen, —OH, —CH
3
, —Cl, —Br, —CN, and —COOR
2
, wherein each R
2
is individually selected from the group consisting of hydrogen and branched and unbranched alkyl groups (preferably C
1
-C
20
, and more preferably C
1
-C
10
). The polymer should comprise less than about 50% by weight, and preferably from about 1-30% by weight of these two monomers.
Even more preferably, the polymer comprises a moiety according to the formula
The polymer should comprise at least about 10% by weight, preferably from about 30-95% by weight, and more preferably from about 30-65% by weight of this moiety, based upon the total weight of the polymer taken as 100% by weight.
The weight average molecular weight of the polymer is preferably less than about 100,000 Daltons, more preferably from about 100-30,000 Daltons, and more preferably from about 1,000-5,000 Daltons. The molar ratio of x:y:z should be from about 0:0:0.2 to about 0.8:0.8:1, and more preferably from about 0.01:0.01:0.5 to about 0.5:0.5:1.
Optionally, the above-described monomers can be polymerized with other monomers to alter the properties (e.g., dry etching speed, reflectivity, etc.) of the polymer and of the final anti-reflective or fill composition including the polymer. Examples of such monomers include those set forth in Table 1.
TABLE 1
Monomer Type
Specific Example
acrylic acid esters
C
1
-C
10
alkyl acrylates
methacrylic acid
C
1
-C
10
alkyl methyacrylates
esters
acrylamides
N-alkylacrylamides, N-arylacrylamides, N,N-
dialkylacrylamides, N,N-arylacrylamides, N-methyl-N-
phenylacrylamide, N-hydroxyethyl-N-methylacryl-
amide, N-2-acetamideethyl-N-acetylacrylamide
methacrylamides
N-akylmethacrylamides, N-arylmethacrylamides, N,N-
dialkylmethacrylamides, N,N-diarylmethacrylamides,
N-hydroxyethyl-N-methylmethacrylamides, N-methyl-
N-phenylmethacrylamides,
N-ethyl-N-phenylmethacrylamides
vinyl ethers
alkyl vinyl ethers, vinyl aryl ethers
vinyl esters
vinyl butyrate, vinyl isobutyrate, vinyl trimethylacetate
styrenes
styrene, alkylstyrenes, alkoxystyrenes, halostyrenes,
hydroxystyrenes, carboxystyrenes
crotonic acid
alkyl crotonates (e.g., butyl crotonate, hexyl crotonate,
esters
glycerine monocrotonate)
allylic compounds
allyl acetates, allyl alcohols, allyl amides
The inventive polymers can be used to prepare anti-reflective and fill compositions by dissolving the polymer in a suitable solvent system. The solvent system should have a boiling point of from about 60-250° C., and preferably from about 100-200° C. The amount of polymer dissolved in the solvent system is from about 0.1-50% by weight polymer, preferably from about 0.1-20% by weight polymer, and more preferably from about 0.1-20% by weight polymer, based upon the total weight of the composition taken as 100% by weight. The solvent system should be utilized at a level of from about 50-99.9% by weight, preferably from about 80-99.9% by weight, and more preferably from about 90-99.9% by weight, based upon the total weight of the composition taken as 100% by weight.
Preferred solvent systems include a solvent selected from the group consisting of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellulose acetate, ethyl cellulose acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropianate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl aceta

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