JP4918909B2 - Stripping composition and stripping method - Google Patents

Description

  The present invention relates to a peeling composition and a peeling method using the same.

In the electronics field, low dielectric constant insulating materials are being developed. In particular, a polyarylene resin has been proposed as a material excellent in application to an interlayer insulating film of a semiconductor element, a stress relaxation layer of a rewiring layer, and the like (see Patent Documents 1 to 3).
Further, a polyarylene resin having a high transparency and a low dielectric constant has been proposed as an embedding material for forming individual pixels in a TFT (thin film transistor) manufacturing process (see Patent Document 4). By applying a highly transparent low dielectric constant material, the response characteristics of the element can be improved and the numerical aperture can be increased.

Furthermore, a photocurable composition obtained by imparting photosensitivity to a polyarylene resin has been proposed (see Patent Documents 5 and 6). If it has photosensitivity, it can be finely processed by photolithography, for example, like a resist. Therefore, there is an advantage that a contact hole can be easily formed in an interlayer insulating film made of, for example, polyarylene resin.
The resist is a process material that is removed in a later step and does not remain in the final product, whereas a material that remains as a member that functions in the final product, such as an interlayer insulating film, is referred to as a direct material in the present invention.

By the way, generally, when a resist is processed by photolithography, a failure may occur from the exposure process to the development process, and a defective product may be manufactured. In this case, if the photocured cured product can be peeled and removed, the manufacturing cost can be reduced. A resist stripping composition has already been proposed (see Patent Document 7).
US Pat. No. 6,361,926 International Publication No. 03/8484 Pamphlet JP-A-10-74750 International Publication No. 2006/137327 Pamphlet JP 7-503740 International Publication No. 2007/119384 Pamphlet JP 2003-122028 A

However, a stripping composition for stripping a polyarylene resin photocured product is not yet known.
Further, since the direct material remains in the final product unlike the resist, high reliability and durability are required. Therefore, it is required that the adhesive force between the direct material and the substrate is high, and an adhesion promoter is used if necessary. For this reason, a direct material cannot be peeled with the peeling composition with weak peeling force. On the other hand, if the peeling force is too strong, not only the direct material but also its lower layer may be peeled off. Therefore, a suitable peeling composition that matches the state of the direct material is required.

  The present invention has been made in view of the above circumstances, and a stripping composition suitable for stripping a direct material obtained by photocuring a curable composition containing a polyarylene resin from a substrate, and this It aims at providing the peeling method using this.

In order to solve the above problems, the stripping composition of the present invention is a stripping composition for stripping a straight material obtained by photocuring a curable composition containing a polyarylene resin having a crosslinkable functional group. The main component is a solvent A composed of one or more selected from the following compound group X.
The compound group X consists of a cyclic ether compound having a dielectric constant of 7 or more, an acyclic ether alcohol compound having a dielectric constant of 7 or more, and an amide compound having a dielectric constant of 7 or more.
The polyarylene resin preferably has a fluorine atom.
The compound group X is preferably composed of tetrahydrofuran, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, propylene glycol monomethyl ether.

  Moreover, the peeling method of this invention peels the direct material obtained by photocuring the curable composition containing the polyarylene resin which has a crosslinkable functional group using the peeling composition of this invention from a base material. It is characterized by doing.

The stripping composition of the present invention can satisfactorily peel off a direct material obtained by photocuring a curable composition containing a polyarylene resin using the composition.
According to the peeling method of this invention, the direct material obtained by photocuring the curable composition containing polyarylene resin can be favorably peeled from a base material.

<Polyarylene resin>
In the present invention, the cured product to be peeled includes a cured product of polyarylene resin having a crosslinkable functional group. The polyarylene resin is a resin having a structure in which a plurality of aromatic rings are bonded via a single bond or a linking group. Examples of the linking group include an ether bond (—O—), a sulfide bond (—S—), a carbonyl group (—CO—), and a divalent group (—SO ₂ —) obtained by removing a hydroxyl group from a sulfonic acid group. It is done. Among the polyarylene resins, a resin having a structure in which aromatic rings are bonded with a linking group containing an ether bond (—O—) is referred to as a polyarylene ether resin. The “polyarylene resin” in the present invention is a concept including a polyarylene ether resin.
Specific examples of the linking group containing an ether bond include an ether bond (—O—) consisting only of an etheric oxygen atom, and an alkylene group containing an etheric oxygen atom in the carbon chain.

The polyarylene resin in the present invention has a crosslinkable functional group. At least a part of the crosslinkable functional group is a reactive functional group that causes a crosslinking reaction or a chain extension reaction by being irradiated with light in the presence of a photosensitizing agent to cure the polyarylene resin.
Specific examples of the crosslinkable functional group include vinyl group, allyl group, methacryloyl (oxy) group, acryloyl (oxy) group, vinyloxy group, trifluorovinyl group, trifluorovinyloxy group, ethynyl group, 1-oxocyclopenta Examples include -2,5-dien-3-yl group, cyano group, alkoxysilyl group, diarylhydroxymethyl group, hydroxyfluorenyl group, cyclobutalene ring, and oxirane ring. From the viewpoint of high reactivity and high crosslink density, a vinyl group, a methacryloyl (oxy) group, an acryloyl (oxy) group, a trifluorovinyloxy group, an ethynyl group, a cyclobutalene ring, and an oxirane ring are preferable. The vinyl group and the ethynyl group are the most preferable from the viewpoint of good heat resistance.
The methacryloyl (oxy) group means a methacryloyl group or a methacryloyloxy group. The same applies to the acryloyl (oxy) group.

Since the polyarylene resin has an aromatic ring, it has good heat resistance and, for example, high reliability can be obtained when it is used as a constituent member of a semiconductor element.
Among the polyarylene resins, in particular, the polyarylene ether resin is preferable in that it has an etheric oxygen atom and thus has a flexible molecular structure and good resin flexibility.
The polyarylene resin is preferably a fluorine-containing polyarylene resin having a fluorine atom. Since it has a fluorine atom, the dielectric constant and dielectric loss of the cured product of the resin are likely to be low, and thus is preferable as a resin for forming an insulating film. When the dielectric constant and dielectric loss of the insulating film are low, a delay in signal propagation speed can be suppressed, and an element having excellent electrical characteristics can be obtained.
In addition, when fluorine atoms are contained, the water absorption rate of the cured product of the resin is lowered, so that it is possible to suppress changes in the bonding state in the bonding electrode and the surrounding wiring portion, or metal deterioration (such as rust). It is excellent in terms of points and the like, and is highly effective in terms of improving the reliability of the element.

  Preferred examples of the fluorine-containing polyarylene resin include fluorine-containing aromatic compounds such as perfluoro (1,3,5-triphenylbenzene) and perfluorobiphenyl; 1,3,5-trihydroxybenzene, 1,1, Reacting a phenolic compound such as 1-tris (4-hydroxyphenyl) ethane with a crosslinkable compound such as pentafluorostyrene, acetoxystyrene, or chloromethylstyrene in the presence of a dehydrohalogenating agent such as potassium carbonate. And the resulting polymer.

<Curable composition>
The curable composition in this invention has photocurability. Specifically, it contains a polyarylene resin and a photosensitizer. Further, it preferably contains a solvent, and may contain additives such as an adhesion improver.
As the photosensitive agent, the solvent, and the additive, known photocurable compositions can be appropriately used.
Specific examples of the photosensitizer include IRGACURE 907 (α-aminoalkylphenone type), IRGACURE 369 (α-aminoalkylphenone type), DAROCUR TPO (acylphosphine oxide type), IRGACURE OXE01 (oxime ester derivative), IRGACURE OXE02 ( Oxime ester derivatives) (all manufactured by Ciba Specialty Chemicals). Of these, DAROCUR TPO, IRGACURE OXE01, and IRGACURE OXE02 are particularly preferable.
Specific examples of the solvent include propylene glycol monomethyl ether acetate (hereinafter also referred to as PEGMEA).
Examples of the adhesion improver include a silane coupling agent. It is preferable to include an adhesion improver in the curable composition because the adhesion between the photocured product (direct material) of the curable composition and the substrate is improved. In addition, the adhesiveness of a base material and a direct material can also be improved also by the method of apply | coating an adhesive improvement agent to a base material previously.

As a curable composition in the present invention, a composition containing an oligomerized cyclobutane described in Patent Document 5 and a photosensitizer, or a polyarylene resin described in Patent Documents 1, 4, and 6 above. A composition containing a photosensitizer can be used.
Furthermore, the curable composition containing the polyarylene resin described in the said patent documents 2 and 3 and a well-known photosensitizer can also be used.

<Direct materials>
The direct material in the present invention is a photocured product obtained by photocuring the curable composition. The straight material is formed on a substrate. The direct material is preferably a film obtained by applying the curable composition on a substrate and curing it by irradiating light.
A specific example of the direct material is an insulating film formed on a substrate such as a semiconductor directly or via a passivation film (made of silicon nitride, polyimide, or the like).
In addition, the base material in this invention is a target object which forms a direct material, for example, when forming an insulating film directly on a board | substrate, this board | substrate is a base material in this invention. When an insulating film is formed on a substrate via a passivation film, a laminate of the substrate and the passivation film is a base material in the present invention.

  In order to form an insulating film on a substrate, for example, first, a solution-like curable composition is applied on the substrate by a coating method such as a spin coating method, and then pre-baked and exposed as necessary. . Ultraviolet rays are often used for exposure. The exposed area is photocured and the unexposed area remains uncured. Development is performed after exposure to remove the curable composition in the unexposed areas. As the developer, the same one as the solvent of the curable composition can be used. Thereafter, heating is performed as necessary to cure the photocured resin (curing step). Thus, an insulating film (direct material) can be formed on the substrate. The thickness of the insulating film is preferably about 1 to 100 μm, and more preferably 3 to 50 μm. Further, a wiring layer is formed on the insulating film in accordance with the element design. Examples of the metal used for the wiring layer include copper, aluminum, titanium, and gold. The step of forming the insulating film and the step of forming the wiring layer are repeated a plurality of times as necessary.

  In this invention, the photocured material (direct material) peeled using the peeling composition is a thing before a curing process. Specifically, after the exposure or development described above, if a defective product is found, a photocured product (direct material) of the defective product is used by using a peeling composition before the curing step. It is preferable to peel and remove from the substrate.

<Peeling composition>
The stripping composition of the present invention contains solvent A as a main component. 50 mass% or more is preferable and, as for the content rate of the solvent A in a peeling composition, 80 mass% or more is more preferable. The upper limit of the content is 100% by mass, and the stripping composition may be a composition composed only of the solvent A.

The solvent A is composed of one or more selected from the compound group X. The compound group X consists of a cyclic ether compound having a dielectric constant of 7 or more, an acyclic ether alcohol compound having a dielectric constant of 7 or more, and an amide compound having a dielectric constant of 7 or more.
If the dielectric constant of the compound used as the solvent A is low, it is considered that the penetrating power into the cured resin (direct material) becomes insufficient. That is, when the dielectric constant of the compound used as the solvent A is less than 7, peeling of the photocured product (direct material) of the polyarylene resin may not proceed sufficiently. The dielectric constant is more preferably 10 or more. The upper limit is preferably 50 or less from the viewpoint of suppressing the influence on the substrate and the like.
Furthermore, as the solvent A, a specific compound is selected. That is, the solvent A has a predetermined dielectric constant and is selected from the group consisting of cyclic ether compounds, acyclic ether alcohol compounds, and amide compounds. Compounds other than these are considered to have insufficient penetration into the cured resin (direct material), and peeling of the photocured product (direct material) of the polyarylene resin may not proceed sufficiently.
The compound used as the solvent A may be liquid at the time of use, and is preferably liquid at 25 ° C.

A preferred example of the cyclic ether compound is tetrahydrofuran (dielectric constant ε = 7.5).
Preferable examples of the acyclic ether alcohol compound include propylene glycol monomethyl ether (ε = 12.3).
Preferable examples of the amide compound include N-methylpyrrolidone (ε = 32), dimethylformamide (ε = 37), dimethylacetamide (ε = 38) and the like.
Of these, amide compounds are more preferred because of their high permeability to the photocured product (direct material) of the fluorine-containing polyarylene resin and high peeling effect. Furthermore, dimethylformamide and / or dimethylacetamide are particularly preferred because of the ease of treatment after peeling.
The solvent A may be one type selected from the above compound group X, or may be used by mixing two or more types, and can be adjusted according to the material of the substrate and the required peeling force.

In addition to the solvent A, the peeling composition may contain other solvents. The content of the other solvent in the stripping composition is preferably 10% by mass or less, and more preferably 5% by mass or less. Zero is acceptable.
For example, when an acid or alkali is added as an additive to the stripping composition, the use of a polyhydric alcohol such as propylene glycol (PG) or glycerin as another solvent reduces the influence of the acid or alkali on the metal. Can do.

  Further, for example, water may be contained in the stripping composition as necessary, for example, to improve the solubility of the additive. The moisture content of the stripping composition is preferably 15% by mass or less, more preferably 10% by mass or less, and most preferably zero. If the water content is higher than 15% by mass, the peeling effect of the polyarylene resin on the photocured product (direct material) tends to be insufficient.

The stripping composition may further contain additives for improving the stripping force, anticorrosives, and the like.
The additive for improving the peeling force is preferably an acid or an alkali. In particular, when a direct material provided on a base material having a metal wiring on its surface is peeled off, it is preferable to use an acid or an alkali that does not contain any metal atom or metal ion. Metal atoms or metal ions can cause a reduction in the reliability of the substrate.
Specific examples of the acid include sulfuric acid, nitric acid, and dodecylbenzenesulfonic acid. Specific examples of the alkali include sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide (TMAH). In particular, the addition of TMAH is preferable in that the effect of improving the peeling force is great. The amount of the acid or alkali added as an additive for improving the peeling force is preferably 0.1 to 10% by mass of the peeling composition.

  When an anticorrosive agent is added to the stripping composition, an effect of protecting the metal constituting the wiring is obtained. In particular, when the stripping composition can come into contact with a metal and the stripping composition contains an acid or an alkali, it is preferable to add an anticorrosive. Examples of the anticorrosive include benzoic acid, ammonium benzoate, catechol, benzotriazole, sorbitol, adenine, gallic acid, glyoxysan, pyrogallol and the like. The addition amount of the anticorrosive is preferably 0.1 to 5% by mass of the stripping composition.

<Peeling method>
The peeling method of this invention peels and removes the photocured material (direct material) of the curable composition containing polyarylene resin formed on the base material using the peeling composition.
The peeling treatment is preferably performed by a method in which the base material on which the direct material is formed is immersed in the peeling composition. In the peeling composition, the substrate may be rocked, or the substrate may be irradiated with ultrasonic waves. The peeling process may be a single wafer process or a batch process. The immersion time is preferably 1 to 60 minutes, more preferably 5 to 20 minutes. The stripping composition can be used at room temperature, but may be heated below the boiling point. It is preferable to heat the peeling composition because the penetration force into the photocured product (direct material) is improved. The use temperature of the stripping composition is preferably 10 to 100 ° C, more preferably 50 to 90 ° C. A post-treatment such as rinsing may be performed after the peeling treatment. Thereafter, it is preferable to perform an appropriate drying treatment.

Although the polyarylene resin is soluble in a solvent, the photocured product cured by light irradiation becomes insoluble or hardly soluble, so that only uncured resin can be removed by development. The photocured product (direct material) remaining after development can be satisfactorily peeled from the substrate by performing a stripping treatment using the stripping composition of the present invention.
In addition, the fluorine-containing polyarylene resin tends to be more difficult to peel off the direct material than the polyarylene resin, but according to the peeling composition of the present invention, as shown in the examples described later, The photocured product of the polyarylene resin can be peeled well.
Further, when the direct material to be peeled is an insulating film formed on a passivation film made of silicon nitride or polyimide, the adhesive force between the passivation film and the direct material is likely to increase, and the direct material is peeled off. Although it tends to be difficult, the stripping composition of the present invention is a photocured material (direct material) on a substrate treated with silicon nitride or polyimide, as shown in Examples below. Can be peeled well.
Therefore, the curable composition in the present invention can be suitably used as a low dielectric constant material constituting a semiconductor element, when a failure occurs from the exposure step to the development step, and a defective product is produced, The photocured product can be peeled and removed. As a result, it is possible to reuse defective products, and the effects of reducing waste and manufacturing costs can be obtained.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
(Preparation Example 1)
A curable composition (I) containing a fluorinated polyarylene ether resin was prepared.
That is, IRGACURE as a photosensitizer is added to a PEGMEA solution containing a polymer obtained by reacting perfluorobiphenyl, 1,1,1-tris (4-hydroxyphenyl) ethane, and pentafluorostyrene in the presence of potassium carbonate. OXE01 (manufactured by Ciba Specialty Chemicals) was added, and a silane coupling agent was further added to obtain a curable composition (I).

(Peel test)
Photocured products of the curable composition (I) were respectively produced under the following three conditions (a) to (c).
(A) A silicon wafer (6 inches) subjected to silicon nitride treatment as a pretreatment and a silane coupling agent applied as an adhesion improver by spin coating is used as a base material, and photocured on the base material Formed.
(B) A silicon wafer (6 inches) subjected to polyimide treatment as a pretreatment and a silane coupling agent applied as an adhesion improver by a spin coating method is used as a base material and photocured on the base material. Formed.
(C) A silane coupling agent as an adhesion improver is applied by spin coating on a silicon wafer (6 inches) that is not subjected to pretreatment, and the curable composition (I) obtained in Preparation Example 1 is applied thereon. Was applied by a spin coating method, and was then photocured by irradiating the entire surface with ultraviolet rays. Thereafter, a photocured film (underlayer film) having a thickness of 7 μm formed by heat treatment at 200 ° C. for 1 hour in a nitrogen atmosphere is used as a base material. Formed.

The photocured product was formed by the following method.
First, the curable composition (I) obtained in Preparation Example 1 was applied onto a substrate by a spin coating method, and then heated at 80 ° C. for 90 seconds with a hot plate to form a coating film having a thickness of 7 μm. The coating film was exposed by irradiating with ultraviolet rays through a mask using an exposure machine UL-7000 (product name) manufactured by Quintel. The irradiation amount was 360 mJ / cm ² . Thereafter, PEGMEA was used as a developing solution, followed by paddle development, followed by drying and cutting the wafer into 2 cm squares.
Thus, a test piece was obtained in which a square-shaped homogeneous film (so-called solid part) having a side of 1 cm made of a photocured product of the curable composition (I) was formed on the substrate.

The test piece which peeled the photocured material on a base material with the following method using the following 11 types of peeling compositions (test No. 1-11) was done with respect to the obtained test piece.
That is, 20 mL of the stripping composition was put in a 100 mL beaker, placed on a hot plate heated to the heating temperature shown in Table 1, and after 5 minutes or longer, the test piece was immersed for 10 minutes and taken out.
Peeling was evaluated visually, and the photocured material (solid film with an area of 1 cm ² ) was peeled off, and among the photocured material (solid film with an area of 1 cm ² ), an area of 0.5 cm ² or more could be peeled off. A case where there was a peeling residue was indicated by Δ, and a case where peeling was not possible was indicated by ×. The results are shown in Table 1.

Test No. The stripping compositions 1 to 11 are as follows.
No. 1: Toluene, dielectric constant ε = 2.4.
No. 2: Propylene glycol monomethyl ether acetate (PGMEA), dielectric constant ε = 8.3.
No. 3: Acetone, dielectric constant ε = 21.
No. 4: Dimethyl sulfoxide (DMSO), dielectric constant ε = 49.
No. 5: Tetrahydrofuran (THF), dielectric constant ε = 7.6.
No. 6: Propylene glycol monomethyl ether (PGME), dielectric constant ε = 12.
No. 7: A mixture comprising 5% by mass of tetramethylammonium hydroxide (TMAH) as an alkali, 80% by mass of PGME, 10% by mass of propylene glycol (PG, dielectric constant ε = 32), and 5% by mass of water.
No. 8: Mixture of 50% by mass of PGME and 50% by mass of dimethylacetamide (DMAc).
No. 9: N-methylpyrrolidone (NMP), dielectric constant ε = 32.
No. 10: Dimethylformamide (DMF), dielectric constant ε = 37.
No. 11: DMAc, dielectric constant ε = 38.

  As shown in the results of Table 1, test No. using the stripping composition of the present invention. In Nos. 5 to 11, the photocured product of the fluorinated polyarylene ether resin could be peeled well even when the pretreatment with high adhesion was performed (conditions a and b). Further, even when a photocured product was formed on the lower layer film after the curing step (condition c), the photocured product of the fluorine-containing polyarylene ether resin could be peeled off satisfactorily, and the lower layer film was not affected.

Claims (4)

A peeling composition for peeling a direct material obtained by photocuring a curable composition containing a polyarylene resin having a crosslinkable functional group,
A stripping composition comprising a solvent A comprising at least one selected from the following compound group X as a main component.
The compound group X consists of a cyclic ether compound having a dielectric constant of 7 or more, an acyclic ether alcohol compound having a dielectric constant of 7 or more, and an amide compound having a dielectric constant of 7 or more.   The stripping composition according to claim 1, wherein the polyarylene resin has a fluorine atom.   The stripping composition according to claim 1 or 2, wherein the compound group X comprises tetrahydrofuran, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, and propylene glycol monomethyl ether.   A direct material obtained by photocuring a curable composition containing a polyarylene resin having a crosslinkable functional group using the peeling composition according to any one of claims 1 to 3, The peeling method characterized by peeling from.