Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-04-18
2003-09-30
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S326000, C430S905000, C430S910000
Reexamination Certificate
active
06627379
ABSTRACT:
BACKGROUND
1. Field of the Disclosure
The present invention relates to photoresist compositions and process using the photoresist compositions. In particular, the present invention relates to photoresist compositions comprising a plurality of polymers, and methods for using the same.
2. Description of the Related Art
Resist flow processes are used in variety of industrial applications including the production of semiconductor devices. Resist flow processes are often used in the production of semiconductor devices to form a fine contact hole pattern. The resist flow process can be used to produce a contact hole pattern which exceeds the resolution of the exposing device. Typically, a resist flow process is used after a pattern is formed on a substrate using a photolithography process. The photolithography process generally involves both an exposure process and a development process. The photolithography process forms a photoresist contact hole pattern having a maximum resolution equal to that of the exposing device. In the resist flow process, this initially formed pattern is then heated to a temperature higher than the glass transition temperature of the photoresist resin which causes the photoresist resin to flow. This flow of photoresist resin reduces the size of contact hole until a fine contact hole necessary for the integration process is obtained (see FIG.
1
).
Thus, the resist flow process makes it possible to obtain contact holes smaller than the resolution of an exposing device. Unfortunately, the resist flow process can result in a sudden or excessive photoresist resin flow (i.e., “overflow”) which may result in a bent or collapsed contact hole pattern profile. This problem occurs typically at a temperature higher than the glass transition temperature of the photoresist resin.
The overflow can occur due to several factors including photoresist's sensitivity to heat, imprecise temperature control, and imprecise control of the flow time. In result of the overflow, contact hole pattern is collapsed.
Attempts to solve the overflow problem by improving control of the baking process, such as maintaining a uniform baking temperature and/or controlling the precise baking time, have been mostly unsuccessful.
SUMMARY OF THE DISCLOSURE
A solution to the above problems is provided by a photoresist composition that comprises a photoresist resin, a photoacid generator and an organic solvent. The photoresist resin comprises a first copolymer comprising a compound of Formula 1:
wherein
R
1
is H, a (C
1
-C
10
) alkyl or a (C
1
-C
10
) aryl, and
a second copolymer comprising a compound of the Formula 2:
wherein R
2
is an acid labile protecting group.
In a refinement of the photoresist composition, a mol % ratio of a:b ranges from about 20:80 to about 80:20.
In a further refinement of the above photoresist composition, a mol % ratio of c:d:e is such that c ranges from about 30 mol % to about 70 mol %, d ranges from about 28 mol % to about 50 mol % and e ranges from about 2 mol % to about 15 mol %.
In a further refinement, a photoresist composition is used in a photoresist flow process.
In a further refinement, the acid labile protecting group is selected from the group consisting of tert-butyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl, 1-tert-butoxyethyl, 1-isobutoxyethyl and 2-acetylmenth-1-yl.
In another refinement, R
1
is a methyl group and R
2
is a butyl.
In a further refinement, a weight % ratio of the first copolymer to the second copolymer ranges from about 20:80 to about 80:20.
In another refinement, the photoacid generator is selected from the group consisting of diphenyl iodide hexafluorophosphate, diphenyl iodide hexafluoroarsenate, diphenyl iodide hexafluoroantimonate, diphenyl p-methoxyphenyl triflate, diphenyl p-toluenyl triflate, diphenyl p-isobutylphenyl triflate, diphenyl p-tert-butylphenyl triflate, triphenylsulfonium hexafluororphosphate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, and mixtures thereof.
In another refinement, the photoacid generator is present in an amount ranging from about 0.05% to about 0.3% by weight of the photoresist resin.
In another refinement, the organic solvent is selected from the group consisting of propylene glycol methyl ether acetate, ethyl lactate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate and cyclohexanone and mixtures thereof.
In a further refinement, the organic solvent is present in an amount ranging from about 400% to about 800% by weight of the photoresist resin.
Another solution to the aforenoted problems is provided by a process for forming a photoresist pattern that comprises the steps of coating the photoresist composition of claim 1 on a substrate of a semiconductor element to form a photoresist film, forming a first photoresist pattern using a lithography process and producing a second photoresist pattern from said first photoresist pattern using a resist flow process.
In a refinement of the above process, the resist flow process comprises heating the first photoresist pattern to a temperature ranging from about 140° C. to about 170° C.
In another refinement, the first and second photoresist patterns comprise a contact hole pattern. A semiconductor element manufactured in accordance with the above process is also disclosed.
REFERENCES:
patent: 5962180 (1999-10-01), Iwanaga et al.
patent: 5976759 (1999-11-01), Urano et al.
patent: 6280900 (2001-08-01), Chiba et al.
patent: 2000-137329 (2000-05-01), None
Adams, US 2001/0053496 A1, Dec. 20, 2001, patent application publication of Ser. No. 09/825,070.*
U.K. Search Report dated Jul. 27, 2001.
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