Polymer remover

Details Polymer remover Polymer remover

2001-08-02

2003-04-29

Carrillo, Sharidan (Department: 1746)

Cleaning and liquid contact with solids

Processes

Using sequentially applied treating agents

C134S002000, C134S022170, C134S022190, C134S025400, C134S036000, C134S042000, C134S902000, C510S175000, C510S176000, C510S245000, C510S254000, C510S257000, C510S506000

Reexamination Certificate

active

06554912

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to the field of removal of polymeric materials from a substrate. In particular, the present invention relates to compositions and methods for the removal of plasma induced polymeric material from electronic devices.
Numerous materials containing polymers are used in the manufacture of electronic devices, such as circuits, disk drives, storage media devices and the like. Such polymeric materials are found in photoresists, solder masks, antireflective coatings, and the like. For example, modem technology utilizes positive-type resist materials for lithographically delineating patterns onto a substrate so that the patterns can be subsequently etched or otherwise defined into the substrate material. The resist material is deposited as a film and the desired pattern is defined by exposing the resist film to energetic radiation. Thereafter the exposed regions are subject to a dissolution by a suitable developer liquid. After the pattern has been thus defined in the substrate the resist material must be completely removed from the substrate to avoid adversely affecting or hindering subsequent operations or processing steps.
It is necessary in such a photolithographic process that the photoresist material, following pattern delineation, be evenly and completely removed from all unexposed areas so as to permit further lithographic operations. Even the partial remains of a resist in an area to be further patterned is undesirable. Also, undesired residue between patterned features can have deleterious effects on subsequent film depositions processes, such as metallization, or cause undesirable surface states and charges leading to reduced device performance.
The semiconductor industry is moving toward sub-quarter micron geometry features. As the geometry of the features gets smaller and pattern density increases, plasma etching, reactive ion etching, ion milling and the like are required for the lithographic process. During such plasma etching, reactive ion etching and ion milling processes, the polymeric material is subjected to conditions that make the removal of such polymeric material difficult. During the plasma etch process a photoresist film forms a hard to remove organometallic polymeric residue on the sidewalls of the various features being etched. Furthermore, the photoresist is extensively cross-linked due to the high vacuum and high temperature conditions in the etch chamber. Known cleaning processes do not acceptably remove such polymeric residue. For example, acetone or N-methylpyrrolidinone is currently used at extreme conditions, which include high temperature and extended cycle times. Such use conditions are often above the flashpoint of the solvent which raises certain environmental, health and safety issues regarding operator exposure. In addition, productivity and throughput are adversely affected by the extended process cycle times required. Even with such extreme stripping conditions, the devices may have to undergo wet strip followed by de-scum (O
2
plasma ash) and a subsequent wet clean for a wet-dry-wet strip process.
U.S. Pat. No. 5,320,709 (Bowden et al.) discloses compositions for the selective removal of organometallic residues remaining after plasma etching of materials having anhydrous ammonium fluoride salt selected from anhydrous ammonium fluoride or anhydrous ammonium bifluoride in a polyhydric alcohol, wherein the composition contains less than 4% by weight added water. The low level of water present in these compositions controls the etch rate and thus makes the compositions selective in the removal of organometallic material without adversely affecting materials such as silicon dioxide. FIG. 3 in this patent clearly shows the dramatic increase in the etch rate of silicon dioxide with increasing water content in the compositions. Such compositions have the drawback of requiring special handling and disposal requirements due to incompatibility with common solvent waste streams, as well as high viscosity which prohibits spray tool processes.
Certain compositions containing a (C
4
)alkanediol, ammonium bifluoride, dipropylene glycol mono-n-butyl ether, 2 to 3% wt water and 10% wt dimethylacetamide have been used as a glass etchant for flat panel displays. Such compositions have not been used to remove post-plasma etch polymeric residue.
U.S. Pat. No. 5,792,274 (Tanabe et al.) discloses a polymer removing composition containing a) a salt of hydrofluoric acid with a metal free base; b) water soluble organic solvent; and c) water. A long list of possible water soluble organic solvents is provided, however, the only solvent combination disclosed is ethylene glycol plus dimethyl sulfoxide (“DMSO”). No other solvent combinations are taught or suggested in this patent.
In addition, other known stripping compositions for post-plasma etch polymer removal applications have numerous drawbacks including, undesirable flammability, toxicity, volatility, odor, necessity for use at elevated temperatures such as up to 100° C., and high cost due to handling regulated materials. A particular problem with advanced next generation semiconductor devices is that known stripping compositions are incompatible with a variety of thin films in such devices, that is, such known stripping compositions cause corrosion of the thin films, specifically copper, and low-k dielectric material present in such advanced devices.
There is thus a continuing need for strippers and post etch polymer removers that effectively remove polymeric material, are more environmentally compatible, do not damage the features and geometries, do not cause corrosion of the substrate, particularly thin metal films, and do not etch dielectric layers in the substrate.
SUMMARY OF THE INVENTION
It has been surprisingly found that polymeric material may be easily and cleanly removed from substrates, particularly 100% copper substrates with dielectric materials. Such polymeric material may be removed according to the present invention without corrosion of underlying metal layers, specifically copper, and without etching of conventional dielectric materials, such as silicon dioxide and low dielectric constant (“low k”) materials, such as hydrogen silsesquioxane, polyarylene ethers, and SILK. It has been further surprisingly found that compositions containing water are effective in removing polymeric material without etching of dielectric materials.
In one aspect, the present invention provides a composition for the removal of polymeric material from a substrate including one or more polyol compounds selected from (C
3
-C
20
)alkanediols, substituted (C
3
-C
20
)alkanediols, (C
3
-C
20
)alkanetriols or substituted (C
3
-C
20
)alkanetriols, one or more glycol ethers, water, a fluoride salt selected from ammonium fluoride, ammonium bifluoride, ammonium-tetramethylammonium bifluoride or mixtures thereof, wherein the water is present in an amount of at least 5% wt based on the total weight of the composition.
In a second aspect, the present invention provides a method of removing polymeric material from a substrate including the step of contacting a substrate containing polymeric material to be removed with the composition described above.
In a third aspect, the present invention provides a composition for the removal of polymeric material from a substrate including one or more polyol compounds selected from (C
3
-C
20
)alkanediols, substituted (C
3
-C
20
)alkanediols, (C
3
-C
20
)alkanetriols or substituted (C
3
-C
20
)alkanetriols, one or more glycol ethers, water, a fluoride salt selected from ammonium fluoride, ammonium bifluoride, ammonium-tetramethylammonium bifluoride or mixtures thereof, one or more corrosion inhibitors, wherein the water is present in an amount of at least 5% wt based on the total weight of the composition.
In a fourth aspect, the present invention provides a composition for the removal of polymeric material from a substrate including one or more polyol compounds selected from (C
3
-C
20
)alkanediols, substituted (C
3
-C
20
)alkan

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