Stock material or miscellaneous articles – Composite
Reexamination Certificate
2002-05-23
2004-12-28
Zacharia, Ramsey (Department: 1773)
Stock material or miscellaneous articles
Composite
C428S474400, C524S190000, C524S553000, C524S555000, C427S346000, C427S368000, C427S385500, C427S422000
Reexamination Certificate
active
06835456
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
Patterning in photolithography is carried out by exposing compounds known as photoresists and then developing them. During exposure, reflections from layers beneath the photoresist may significantly impair pattern quality and the faithfulness of the patterns to be reproduced. Antireflective layers are normally used in order to reduce the pattern quality deterioration due to light reflections.
Antireflective layers or coatings (ARC) have the function of absorbing light of the wavelength used to expose the photoresist. They are required to be highly compatible with the photoresist and must be able to be applied uniformly in the desired layer thickness. Compatibility between the antireflective layer and the photoresist comprehends the photoresist and the antireflective layer being able to be coated over one another without any detachment of the layers from one another or the formation of an undefined or even insoluble boundary between the two layers.
For resists of the kind known as chemical amplification resists (CAR) it would be deleterious were the antireflective layer to contain or release components which impair the performance of the CAR. Chemical amplification resists operate, for example, in accordance with the principle of acid catalysis, a strong acid being formed in the course of exposure. For chemical amplification resists, accordingly, the antireflective layer should not give a basic reaction and neutralize the acid.
In photolithography it is normal for different wavelengths to be used for exposing a resist. Consequently it is of advantage to produce antireflective layers that are suitable for use at different wavelengths.
It is prior art to produce a resist from a bottom resist and a top resist. In this case the bottom resist is applied first to the substrate and the top resist is then disposed on it. In the case of a multi-layer system the bottom resist is the lower or lowermost resist layer. Normally, the bottom resist is not photoreactive itself. Where, for example, a resist is formed from two layers, the top resist is exposed and gives a photoreactive reaction, so that it can subsequently be developed. The pattern thus produced in the top resist is normally transferred thereafter into the underlying bottom resist by appropriate process steps. This can be done, for example, using reactive ion etching with oxygen plasma, provided the top resist is stable to the plasma and the bottom resist can be etched with the plasma. Where the top resist contains silicon, for example, reactive ion etching can be carried out in an oxygen-containing plasma for the patterning of the bottom resist.
Where the bottom resist and/or the antireflective layer remains on the substrate, it must exhibit a high level of temperature stability which is able to withstand at least subsequent deposition of silicon oxide or silicon nitride to passivate a semiconductor substrate.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an antireflective, a layer-forming composition, a layer configuration containing the antireflective layer, and a process for producing the antireflective layer which overcome the above-mentioned disadvantages of the prior art methods, compositions, and devices of this general type, in which the antireflective layer is adjustable in its absorption wavelength and is stable to temperatures above 400° C. In the context of the invention, antireflective compositions and antireflective layers relate to compositions and layers that absorb light of the wavelength used to expose the photoresist.
With the foregoing and other objects in view there is provided, in accordance with the invention, a layer-forming antireflective composition. The layer-forming antiflective composition of the invention contains the following components:
a) a base polymer containing a poly(hydroxyamide) and/or a polybenzoxazole; and
b) a dye component selected from the following dye classes: methine dyes, methine derivatives, azomethine dyes and their derivatives, coumarin dyes and their derivatives, triphenylmethane dyes and their derivatives, and azo dyes and their derivatives.
For the purposes of the invention, derivatives of the individual dye classes are dyes that, with the same chromophoric group present, e.g., the azo group, possess different substituents on the chromophoric group.
Poly(hydroxyamides) are polymers with peptide linkages between their monomer units. The monomers of the poly(hydroxyamides) have the following general formulae C) and D):
where n is an integer between 2 and about 100 and m is 0 or 1.
I) The group R is selected from the following aromatic and heteroaromatic groups:
where m is 0 or 1 and X is selected from the following groups:
Groups suitable as the groups Y, Z, Z
1
and Z
2
listed under X include the following:
1) Y is selected from the following groups:
—(CH
2
)
0
— where 0=2 to 10 and
where p=0 or 1.
where Z is selected from the groups specified below under 2) and E is selected from the following groups:
in which q is from 2 to 14 and r is from 2 to 18 and Z
1
is a group 3) mentioned below and Z
2
is a group 4) mentioned below.
2) Z is selected from the following groups:
H and C1 to C6 alkyl groups;
3) Z
1
is selected from the following groups:
C1 to C10 alkyl groups and aryl;
4) Z
2
is selected from aryl and heteroaryl groups.
II) The group R
1
in the above-mentioned general formulae C) and D) is selected from the following groups:
where X represents the groups indicated above and m is 0 or 1 and q is from 2 to 14 and r is from 2 to 18.
The dye component absorbs the light used to expose the photoresist, with the consequence that the layer-forming composition is antireflective. From the dye classes mentioned above, the following dyes are preferred in each case.
From the class of the azo dyes: chrysophenine, Direct Yellow 50 (Aldrich Chemie), Direct Yellow 27 (Aldrich Chemie), Cibacron brilliant yellow, methyl orange, and para red.
From the class of the methine dyes: 3-ethyl5-[2-(3-methylthiazolidin-2-ylidene)ethylidene]-2-thioxooxazoliding-4-one and 5-(4-dimethylaminobenzylidene)rhodanine.
From the class of the azomethine dyes: phenol blue, N-(4-ethyloxybenzylidene)-4-butylaniline, and N,N-terephthalylidenebis(4-butylaniline).
From the class of the coumarin dyes: coumarin 6, coumarin 7, and coumarin 152.
From the class of the triphenylmethane dyes: crystal violet, crystal ponceau 6R, malachite green, fuchsin, and benzaurin.
In these systems, the poly(hydroxyamide) and/or polybenzoxazole serves as the base polymer, embedded within which there is at least one of the afore-mentioned dyes. The dyes are lodged in the polymer matrix without being connected to it by chemical bonds. This has the advantage of particularly simple preparation of the antireflective composition of the invention without the need for additional reactive groups for linking the dyes to the base polymer. The base polymers have the advantage of possessing stability to temperatures above 450° C. and, preferably above 480° C. The inclusion of at least one of the dyes allows a high level of absorption of light in a very broad wavelength range below 450 nm.
The invention further provides an antireflective configuration of layers in which disposed on a substrate there is an antireflective layer which contains one of the above-mentioned antireflective compositions of the invention. Disposed on the antireflective layer is a photoresist layer.
The antireflective layer of the invention has a dielectric constant of, for example, less than 3, whereby electrical coupling through the antireflective layer is relatively low. When the antireflective layer of the invention is coated with a photoresist, an advantageous and surprising result is that no interlayer is formed at the boundary between the photoresist and the antireflective layer.
In comparison, the coating of a simple poly(hydroxyamide) might result in the formation of an interlayer. The interlayer is formed when, for example, the photoresist react
Sezi Recai
Walter Andreas
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Stemer Werner H.
Zacharia Ramsey
LandOfFree
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