Plasma etching residue removal

Details Plasma etching residue removal Plasma etching residue removal

2000-02-25

2002-11-05

Webb, Gregory E. (Department: 1751)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

For cleaning a specific substrate or removing a specific...

C510S176000, C510S177000, C510S178000, C430S256000, C438S694000, C438S745000

Reexamination Certificate

active

06475966

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 treated 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. During manufacture of such electronic devices, the polymeric material is subjected to conditions that make the removal of such polymeric material difficult.
For example, modern 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 resist residues between patterned lines can have deleterious effects on subsequent processes, such as metallization, or cause undesirable surface states and charges.
Known photoresist removal or stripping formulations are typically contain strong alkaline solutions, organic polar solvents or strong acids and oxidizing agents. Typical organic polar solvents include pyrolidones such N-methyl pyrrolidone, N-ethyl pyrrolidone, N-hydroxyethyl pyrrolidone and N-cyclohexyl pyrrolidone; amides including dimethylacetamide or dimethylformamided; phenols and derivatives thereof. Such solvents have been used in combination with amines or other alkaline material. For example, U.S. Pat. No. 5,334,332 (Lee) discloses a composition for removing etching residue containing 5 to 50% hydroxylamine, 10 to 80% of at least one alkanolamine, and water. U.S. Pat. No. 4,401,747 (Ward et al.) discloses a stripping composition containing 30 to 90% 2-pyrrolidinone and 10 to 70% dialkyl sulfone.
Within the last 5 years, technology for storage media has grown exponentially and has driven magnetoresistive read-write device performance through miniaturization and higher area density which today exceeds 20 Gb/in
2
. In order to keep pace with next generation technology, read-write head manufacturers are utilizing advanced photoresists and multi component ion etch recipes to achieve desired thin film stack patterns. To successfully integrate multiple film stacks into sub-micron features with the correct magnetic and signal sensitivity, each layer within such devices must be clean from polymer, ionic and other forms of organic/inorganic contamination or residue. Such undesired residue will adversely affect the performance and reliability of the device.
Plasma etching, reactive ion etching and ion milling are required as the geometry of features get smaller and pattern density increases. 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-methyl pyrrolidinone 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 need manual “swabbing”, or brushing, to remove tenacious “rabbit ear”-type polymeric residue from the fine features.
For example, WO 98/10050 (Honda et al.) discloses compositions for the removal of plasma etching residues including a water, at least one hydroxylammonium compound and at least one basic compound selected from amines and quaternary ammonium hydroxides and having a pH of 2 to 6.
In addition, known stripping compositions have numerous other 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.
There is thus a continuing need for strippers that effectively remove plasma etching polymeric residue, are more environmentally compatible, and do not cause corrosion of the substrate.
SUMMARY OF THE INVENTION
It has been surprisingly found that plasma etching polymeric residue may be easily and cleanly removed from substrates using an alkaline system. Such plasma etching polymeric residue may be effectively removed according to the present invention without corrosion of underlying metal layers.
In one aspect, the present invention provides a composition for the removal of plasma etching polymeric residue from a substrate including one or more polar aprotic solvents, one or more first polymer dissolution enhancing bases selected from tetra(C
1
-C
6
)alkylammonium hydroxide, tetra(C
1
-C
6
)alkylammonium carbonate, tetra(C
1
-C
6
)alkylammonium acetate, tetra(C
1
-C
6
)alkylammonium citrate or choline hydroxide, one or more second polymer dissolution enhancing bases selected from hydroxylamine, hydroxylamine formate or hydroxylamine buffered with carboxylic acid.
In a second aspect, the present invention provides a method of removing plasma etching polymeric residue from a substrate including the step of contacting a substrate containing plasma etching polymeric residue to be removed with the composition described above.
DETAILED DESCRIPTION OF THE INVENTION
As used throughout this specification, the following abbreviations shall have the following meanings unless the context clearly indicates otherwise: DMSO=dimethyl sulfoxide; TMAH=tetramethylammonium hydroxide; DI=deionized; %wt=percent by weight; g=gram; ° C.=degrees Centigrade; and min=minute. All percents are by weight. All numerical ranges are inclusive.
The terms “stripping” and “removing” are used interchangeably throughout this specification. Likewise, the terms “stripper” and “remover” are used interchangeably. “Alkyl” refers to linear, branched and cyclic alkyl. As used throughout this specification, the term “aprotic” refers to compounds that do not accept or yield a proton. The term “side wall polymer” refers to the organometallic polymeric residue remaining after plasma etching.
The compositions of the present invention include one or more polar aprotic solvents, one or more first polymer dissolution enhancing bases selected from tetra(C
1
-C
6
)alkylammonium hydroxide, tetra(C
1
-C
6
)alkylammonium carbonate, tetra(C
1
-C
6
)alkylammonium acetate, tetra(C
1
-C
6
)alkylammonium citrate or choline hydroxide, one or more second polymer dissolution enhancing bases selected from hydroxylamine, hydroxylamine formate or hydroxylamine buffered with carboxylic acid, and optionally one or more organic additives.
The polar aprotic solvents suitable for use in the present invention include, but are not limited to, dimethyl sulfoxide, sulfolane, dimethyl sulfurdioxide, and the like. It is preferred that the polar aprotic solvent is dimethyl sulfoxide or sulfolane. Typically, the amount of polar aprotic solvent is in t

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