JP2000265057A - Heat-resistant resin precursor composition, production of heat-resistant resin, and heat-resistant resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having a low permittivity and excellent heat resistance by including a heat-resistant resin precursor which forms a heat-resistant resin when heated and a solvent having a boiling point higher than the temperature at which the precursor reacts to form a heat-resistant resin and lower than the glass transition temperature of the heat-resistant resin. SOLUTION: This composition comprises a heat-resistant resin precursor which reacts to form a heat-resistant resin when heated and a solvent (e.g. 2-phenoxyethanol) having a boiling point higher than the temperature at which the heat-resistant resin precursor reacts to form a heat-resistant resin and lower than the glass transition temperature of the heat-resistant resin as essential components and contains, in addition, a fine inorganic filter (e.g. silicon oxide). The composition is reacted at a temperature lower than the boiling point of the solvent to form a heat-resistant resin and is heat-treated at a temperature lower than the glass transition temperature of the heat-resistant resin to obtain microvoid-containing heat-resistant resin. The heat-resistant resin precursor is exemplified by a polyimide precursor such as a polyamic acid or a polybenzoxazole such as polyhydroxamide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant resin, and more particularly, to a heat-resistant resin precursor composition having excellent characteristics for use in electric / electronic equipment and semiconductor devices, and a method for producing a heat-resistant resin. And heat-resistant resins.

[0002]

2. Description of the Related Art Among the characteristics required for materials for electric / electronic devices and semiconductor devices, electric characteristics and heat resistance are the most important characteristics. In particular, in recent years, with miniaturization of circuits and speeding up of signals, an insulating material having a low dielectric constant has been required. A heat-resistant resin is expected as a material for satisfying these two characteristics. For example, conventionally used inorganic insulating materials such as silicon dioxide exhibit high heat resistance, but have a high dielectric constant, and at the same time, the required characteristics are becoming more sophisticated. A heat-resistant resin represented by a polyimide resin is excellent in electric properties and heat resistance and can achieve both of the two properties, and is actually used for a solder resist, a coverlay, a passivation film, and the like.

[0003] However, with the recent advancement of functions and performance of semiconductors, remarkable improvements in electrical characteristics and heat resistance have been required, so that higher performance resins have been required. In particular, a low dielectric constant material having a dielectric constant of less than 2.5 is expected, and does not reach the characteristics required by conventional heat-resistant resins. Until now, in the case of polyimide, the resin composition contains a thermally decomposable resin other than the polyimide, and the heating step decomposes the thermally decomposable resin to form voids, thereby forming a dielectric constant of the heat resistant resin formed product. However, in semiconductor applications, since the heating step is usually performed in an oxygen-free state, the carbonized pyrolyzable resin remains, and the insulating property becomes a problem. .

[0004]

SUMMARY OF THE INVENTION The present invention provides a heat-resistant resin precursor composition, a method for producing a heat-resistant resin, and a heat-resistant resin, which exhibit an extremely low dielectric constant, good insulation properties and excellent heat resistance. The purpose is to do.

[0005]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned conventional problems, and as a result, completed the present invention by the following means.

That is, 1. A heat-resistant resin precursor (A) that generates a heat-resistant resin by a reaction by heating; and a glass transition of the heat-resistant resin having a boiling point higher than a temperature at which the heat-resistant resin precursor reacts to form a heat-resistant resin. A heat-resistant resin precursor composition containing a solvent (B) lower than the temperature as an essential component,

[0007] 2. The heat-resistant resin is polyimide,
Heat-resistant resin precursor composition,

[0008] 3. The heat-resistant resin precursor composition according to 1, wherein the heat-resistant resin is polybenzoxazole,

4. The heat-resistant resin precursor composition according to the above 2 or 3, wherein the heat-resistant resin has a fluorine or fluoroalkyl group,

[0010] 5. After reacting the heat-resistant resin precursor composition according to any one of the above 1 to 4 at a temperature lower than the boiling point of the solvent (B) in the above 1 to form a heat-resistant resin, the solvent (B A) a method for producing a heat-resistant resin having a step of heat-treating at a temperature higher than the boiling point and lower than the glass transition temperature of the heat-resistant resin;

6. A heat-resistant resin produced by the production method of the above item 5.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-resistant resin precursor composition of the present invention is obtained by reacting the heat-resistant resin precursor (A), which produces a heat-resistant resin by a reaction by heating, with the heat-resistant resin precursor having a boiling point. And a solvent (B) which is higher than the temperature at which the heat-resistant resin is formed and lower than the glass transition temperature of the heat-resistant resin, and is reacted at a temperature lower than the boiling point of the solvent (B) to form a heat-resistant resin. After the resin is formed, a heat-resistant resin having a low dielectric constant is obtained by a heat treatment at a temperature higher than the boiling point of the solvent (B) and lower than the glass transition temperature of the heat-resistant resin.

In this method, after the heat-resistant resin precursor (A) is reacted by heating to form a heat-resistant resin, the remaining solvent (B) is volatilized at a temperature lower than the glass transition temperature of the heat-resistant resin. In this way, minute voids are formed, or the density of the heat-resistant resin is reduced, thereby reducing the dielectric constant of the entire heat-resistant resin formed product.

The minute voids formed to reduce the dielectric constant of the heat-resistant resin of the present invention have a diameter of 50 nm or less, preferably 10 nm or less.
The ratio of the minute voids is preferably 5 to 90 vol% based on the entire heat-resistant resin formed product.

In the present method, a non-volatile heat-decomposable resin component is not used, so that good insulating properties can be obtained without leaving carbides.

Further, the heat-resistant resin precursor used in the present invention is insoluble or has a very low solubility in the solvent (B) after being converted into a heat-resistant resin by a reaction by heating, and Since the glass transition temperature at which the molecular chain starts to move is higher than the boiling point of the solvent, it is possible to prevent the minute voids from being crushed or the resin from aggregating and increasing the density when the solvent component volatilizes. .

Examples of the heat-resistant resin precursor (A) which produces a heat-resistant resin by a reaction by heating in the present invention include polyimide precursors such as polyamic acid, polyamic acid ester and polyisoimide; Examples include, but are not limited to, polybenzoxazole precursors such as hydroxyamide esters, polybenzothiazole precursors such as polymercaptoamide, bismaleimide, bisnadiimide, and the like. Of these,
Since polyimide and polybenzoxazole are excellent in characteristics required for electronic devices and semiconductor devices such as low impurity concentration in addition to heat resistance, it is particularly preferable to use these precursors. Further, it is preferable that these heat-resistant resins have a fluorine or fluoroalkyl group in the resin chemical structure, since the dielectric constant can be particularly reduced.

In the present invention, the solvent (B) having a boiling point higher than the temperature at which the heat-resistant resin precursor reacts to form a heat-resistant resin and lower than the glass transition temperature of the heat-resistant resin is
Depending on the type of heat-resistant resin to be combined, the temperature at which the polyimide precursor reacts to form a polyimide is 200 ° C. or higher in a polyimide having a general chemical structure, and the other heat-resistant resin precursors listed above are used. Since the reaction temperature is higher than this, it is essential that the boiling point be 200 ° C. or higher, and preferably the boiling point is 220 ° C. or higher.

On the other hand, the glass transition temperature of the heat-resistant resin in the present invention is set to 20 due to the chemical structure of the molecular chain of polyimide or the like.
Although there are many types from about 0 ° C. to 400 ° C. or higher, it is generally preferable to be 300 ° C. or higher because it is necessary to have heat resistance required for a semiconductor device. The higher the glass transition temperature, the better.

That is, the upper limit of the boiling point of the solvent (B) of the present invention is preferably 300 ° C. or lower, but when the glass transition temperature of the heat-resistant resin is higher, the boiling point is within the range. It may be higher temperature. Examples of such solvents include 2-phenoxyethanol,
Triethylene glycol monobutyl ether, tetraethylene glycol, tetraethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether acetate, tetraethylene glycol dimethyl ether, tetrapropylene glycol monomethyl ether, tetrapropylene glycol monomethyl ether acetate, tetrapropylene glycol dimethyl ether, etc. It is not limited to.

The heat-resistant resin precursor composition of the present invention is in the form of a liquid or paste, and is applied and heated to obtain a solid resin formed product. For this reason, in the heat-resistant resin precursor composition of the present invention, the above-mentioned for the purpose of obtaining the storage stability and applicability of the heat-resistant resin precursor composition and for controlling the thickness and porosity of the formed resin. In addition to the solvent, a solvent having a boiling point equal to or lower than the temperature at which the heat-resistant resin precursor reacts can be used. Preferred examples of such a solvent include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, and propylene glycol monomethyl. Examples thereof include, but are not limited to, ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and the like. Further, two or more of these may be used at the same time.

The heat-resistant resin precursor composition of the present invention can be used in the form of a paste containing a fine inorganic filler. Preferred examples of the inorganic filler include silicon oxide, aluminum oxide, titanium oxide, aluminum hydroxide, and the like, but are not limited thereto.

Using the heat-resistant resin precursor composition of the present invention,
A heat-resistant resin having a low dielectric constant can be formed by heat-curing according to the above-described manufacturing method. The heat curing is preferably performed in an oven that can exhaust the volatilized components, and is preferably performed in an inert gas atmosphere to avoid an increase in the dielectric constant due to oxidation of the heat-resistant resin.

[0024]

EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 (1) Synthesis of Polyimide Precursor In a separable flask equipped with a stirrer, a nitrogen inlet tube, and a raw material inlet, 2,2, -bis (4- (4,4′-amino) Phenoxy) phenyl) hexafluoropropane 5.1
8 g (0.01 mol) and 9.60 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl
(0.03 mol) is dissolved in 200 g of dried N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP). The solution was cooled to 10 ° C. under dry nitrogen, and pyromellitic dianhydride 6.54 (0.03 mol) and hexafluoroisopropylidene-2,2-bis (phthalic anhydride) 4.44 g.
(0.01 mol). Five hours after the introduction, the temperature was returned to room temperature, and the mixture was stirred at room temperature for 2 hours to obtain a solution of polyamic acid as a polyimide precursor. This solution was dropped into 20 times the volume of water to collect the precipitate, and dried under vacuum at 25 ° C. for 72 hours to obtain a solid of polyamic acid.

(2) Measurement of the temperature at which the resin is formed from the precursor and the glass transition temperature of the resin The temperature at which the polyamic acid synthesized as described above reacts with the polyimide was measured by a differential thermobalance to be about 220.
° C. 5.0 g of this polyamic acid was added to NMP.
After dissolving in 15.0 g and applying it on a glass substrate subjected to mold release treatment, it was kept in an oven at 120 ° C. for 30 minutes and then at 230 ° C. for 9 minutes.
Hold for 0 minutes to form a film, and after removing the film from the substrate,
Heating was performed at 00 ° C. for 90 minutes to obtain a polyimide film as a heat-resistant resin. The glass transition temperature of this polyimide was 345 ° C. as measured by dynamic viscoelasticity measurement.

(3) Preparation of Precursor Composition and Production of Heat-Resistant Resin 10.0 g of the polyamic acid synthesized above was added to NMP4
After dissolving in 0.0 g, 6.0 g of 2-phenoxyethanol (boiling point: 245 ° C.) was added and stirred to obtain a heat-resistant resin precursor composition. This heat-resistant resin precursor composition was spin-coated on a silicon wafer on which a chromium film having a thickness of 100 nm was formed, and then cured by heating in an oven in a nitrogen atmosphere. In the case of heat curing, after holding at 120 ° C. for 30 minutes, 230
After holding at 120 ° C. for 120 minutes, holding at 320 ° C. for 180 minutes, raising the temperature to 345 ° C., and gradually returning the temperature to room temperature over 90 minutes. 0.8 μm thick
A heat resistant resin film was obtained. An area of 1 cm ² on this film
Was formed by vapor deposition, and the capacitance between the electrode and chromium on the substrate was measured by an LCR meter.
The dielectric constant of the heat-resistant resin calculated from the film thickness, the electrode area, and the capacitance was 2.4.

Example 2 (1) Synthesis of Polyimide Precursor 2, 2 used in the synthesis of the polyimide precursor of Example 1
5.18 g of 2, -bis (4- (4,4′-aminophenoxy) phenyl) hexafluoropropane (0.01 m
ol) and 9.60 g (0.03 mol) of 3,3′-dimethyl-4,4′-diaminobiphenyl, 8.01 g (0.04 mol) of 4,4′-diaminodiphenyl ether.
In addition, pyromellitic dianhydride 6.54 (0.03 mol
Example 1 except that l) and 4.44 g (0.01 mol) of hexafluoroisopropylidene-2,2-bis (phthalic anhydride) were changed to 8.72 (0.04 mol) of pyromellitic dianhydride. In the same manner as in 1, a solution of polyamic acid as a polyimide precursor was obtained. This solution was dropped into 20 times the volume of water to collect the precipitate, and dried under vacuum at 25 ° C. for 72 hours to obtain a solid of polyamic acid.

(2) Measurement of the temperature at which the resin is formed from the precursor and the glass transition temperature of the resin The temperature at which the polyamic acid synthesized as described above reacts with the polyimide was measured using a differential thermobalance.
° C. 5.0 g of this polyamic acid was added to NMP.
Dissolved in 20.0 g, coated on a glass substrate subjected to mold release treatment, kept in an oven at 120 ° C. for 30 minutes, and then heated at 250 ° C. for 9 minutes.
Hold for 0 minutes to form a film, and after removing the film from the substrate,
Heating was performed at 50 ° C. for 90 minutes to obtain a polyimide film as a heat-resistant resin. The glass transition temperature of this polyimide measured by dynamic viscoelasticity measurement was 419 ° C.

(3) Preparation of Precursor Composition and Production of Heat-Resistant Resin 10.0 g of the polyamic acid synthesized above was added to NMP4
After dissolving in 0.0 g, 12.0 g of tetraethylene glycol dimethyl ether (boiling point: 275 ° C.) was added and stirred to obtain a heat-resistant resin precursor composition. 100nm thickness
This heat-resistant resin precursor composition was spin-coated on a silicon wafer on which chromium was formed, and then cured by heating in an oven under a nitrogen atmosphere. In the case of heat curing, after holding at 120 ° C. for 30 minutes and then at 260 ° C. for 120 minutes, 400
The temperature was maintained at 90 ° C. for 90 minutes, and gradually returned to room temperature over 120 minutes. Thus, a 0.7 μm-thick heat-resistant resin film was obtained. The dielectric constant of this heat-resistant resin was measured in the same manner as in Example 1 and found to be 2.4.

Example 3 (1) Synthesis of polybenzoxazole precursor 25 g of 4,4′-hexafluoroisopropylidenediphenyl-1,1 ′ dicarboxylic acid, 45 ml of thionyl chloride
And 0.5 ml of dry DMF was put in a reaction vessel and reacted at 60 ° C. for 2 hours. After completion of the reaction, excess thionyl chloride was distilled off by heating and reduced pressure. The precipitate was recrystallized using hexane to obtain 4,4'-hexafluoroisopropylidenediphenyl-1,1'dicarboxylic acid chloride. 7.32 g of 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane in a separable flask equipped with a stirrer, nitrogen inlet tube, and dropping funnel.
(0.02 mol) dried dimethylacetamide 1
Of pyridine and 3.96 g of pyridine (0.05 mol).
After addition of 1), 8.58 g (0.02 mol) of 4,4′-hexafluoroisopropylidenediphenyl-1,1′-dicarboxylic acid chloride synthesized above was added to 50 g of dimethylacetamide at −15 ° C. under dry nitrogen introduction. Was dissolved and dropped over 30 minutes. After completion of the dropwise addition, the mixture was returned to room temperature and stirred at room temperature for 5 hours. Thereafter, the reaction solution was added dropwise to 1000 ml of water, and the precipitate was collected.
By vacuum drying for a period of time, a solid substance of polyhydroxyamide, which is a polybenzoxazole precursor, was obtained.

(2) Measurement of the temperature at which the resin is formed from the precursor and the glass transition temperature of the resin The temperature at which the polyhydroxyamide synthesized as described above reacts with the polybenzoxazole was examined using a differential thermobalance. there were. Also, 5.0 g of this polyhydroxyamide was dissolved in 20.0 g of NMP, applied on a glass substrate subjected to mold release treatment, and then placed in an oven.
After holding at 240 ° C. for 30 minutes, forming a film by holding at 240 ° C. for 90 minutes, peeling the film from the substrate, and further heating at 400 ° C. for 90 minutes,
A film of polybenzoxazole, which is a heat-resistant resin, was used. The glass transition temperature of this polybenzoxazole was 362 ° C. as measured by dynamic viscoelasticity measurement.

(3) Preparation of Precursor Composition and Production of Heat Resistant Resin 10.0 g of the polyhydroxyamide synthesized as described above was dissolved in 50.0 g of NMP, and then 6.0 g of triethylene glycol monobutyl ether (boiling point: 271 ° C.) Was added and stirred to obtain a heat-resistant resin precursor composition. Thickness 10
This heat-resistant resin precursor composition was spin-coated on a silicon wafer on which a 0-nm chromium film was formed, and then cured by heating in an oven in a nitrogen atmosphere. In the case of heat curing, 12
After holding at 0 ° C. for 30 minutes and holding at 260 ° C. for 120 minutes,
The temperature was maintained at 340 ° C. for 180 minutes, and after raising the temperature to 360 ° C., the temperature was gradually returned to room temperature over 100 minutes. Thus, a heat-resistant resin film having a thickness of 0.8 μm was obtained.
The dielectric constant of this heat-resistant resin was measured in the same manner as in Example 1 and was 2.2.

Comparative Example 1 The procedure of Example 2 was repeated except that 12.0 g of tetraethylene glycol dimethyl ether (boiling point: 275 ° C.) used in preparing the polyimide precursor composition of Example 2 was not added. The dielectric constant of the obtained heat-resistant resin was 3.5.

Comparative Example 2 The procedure of Example 2 was repeated except that 12.0 g of tetraethylene glycol dimethyl ether (boiling point: 275 ° C.) used in preparing the polyimide precursor composition was changed to 12.0 g of 2-phenoxyethanol (boiling point: 245 ° C.). All were performed in the same manner as in Example 2. The dielectric constant of the obtained heat-resistant resin was 3.5.

[Comparative Example 3] In the heat-resistant resin production process of Example 2, after heat-curing in an oven under a nitrogen atmosphere, the film was held at 120 ° C for 30 minutes, then at 300 ° C for 120 minutes, and then heated at 400 ° C. The procedure was the same as in Example 2 except that the temperature was kept at 90 ° C. for 90 minutes and the temperature was gradually returned to room temperature over 120 minutes. The dielectric constant of the heat-resistant resin was 3.5.

Comparative Example 4 (1) Synthesis of Polyimide Precursor 2, 2 used in the synthesis of the polyimide precursor of Example 1
5.18 g of 2, -bis (4- (4,4′-aminophenoxy) phenyl) hexafluoropropane (0.01 m
ol) and 9.60 g (0.03 mol) of 3,3'-dimethyl-4,4'-diaminobiphenyl in 11.69 g of 1,3-bis (3-aminophenoxy) benzene (0.
04mol) and pyromellitic dianhydride 6.54
(0.03 mol) and 4.44 g of hexafluoroisopropylidene-2,2-bis (phthalic anhydride) (0.04 mol).
1 mol) and 4,4'-oxydiphthalic anhydride 1
A polyamic acid solution as a polyimide precursor was obtained in the same manner as in Example 1, except that the solution was changed to 2.41 (0.04 mol). This solution was dropped into 20 times the volume of water to collect the precipitate, and dried under vacuum at 25 ° C. for 72 hours to obtain a solid of polyamic acid.

(2) Measurement of the temperature at which the resin is formed from the precursor and the glass transition temperature of the resin The temperature at which the polyamic acid synthesized as described above reacts with the polyimide was measured by a differential thermobalance to be about 220.
° C. 5.0 g of this polyamic acid was added to NMP.
Dissolved in 20.0 g, coated on a glass substrate subjected to mold release treatment, kept in an oven at 120 ° C. for 30 minutes, and then heated at 250 ° C. for 9 minutes.
Hold for 0 minutes to form a film, and after peeling off the film from the substrate,
Heating was performed at 00 ° C. for 90 minutes to obtain a polyimide film as a heat-resistant resin. The glass transition temperature of this polyimide was 189 ° C. as measured by dynamic viscoelasticity measurement.

(3) Preparation of Precursor Composition and Production of Heat Resistant Resin 10.0 g of the polyamic acid synthesized as described above was added to NMP4
After dissolving in 0.0 g, 12.0 g of 2-phenoxyethanol (boiling point: 245 ° C.) was added and stirred to obtain a heat-resistant resin precursor composition. This heat-resistant resin precursor composition was spin-coated on a silicon wafer on which a chromium film having a thickness of 100 nm was formed, and then cured by heating in an oven in a nitrogen atmosphere. In the case of heat curing, 25 minutes after holding at 120 ° C. for 30 minutes
After maintaining at 0 ° C. for 120 minutes, the temperature was maintained at 300 ° C. for 90 minutes, and gradually returned to room temperature over 120 minutes. Thus, a 0.7 μm-thick heat-resistant resin film was obtained. Thereafter, the dielectric constant of this heat-resistant resin was measured in the same manner as in Example 1, and it was 3.2.

In Examples 1 to 3, the dielectric constant was 2.5
The following very low heat-resistant resin could be obtained. Particularly, in Examples 1 and 3, a lower dielectric constant could be obtained because the heat-resistant resin had a fluorine or fluoroalkyl group.

In Comparative Example 1, since a solvent having a boiling point higher than the temperature at which the heat-resistant resin precursor reacts to form a heat-resistant resin and lower than the glass transition temperature of the heat-resistant resin was not contained, the dielectric constant was low. Could not be reduced.

In Comparative Example 2, the dielectric constant could not be reduced because the boiling points of the solvents used were all lower than the temperature at which the heat-resistant resin precursor reacted to form a heat-resistant resin.

In Comparative Example 3, the dielectric constant could not be reduced because the step of forming a heat-resistant resin by reacting at a temperature lower than the boiling point of the solvent was not performed.

In Comparative Example 4, the dielectric constant could not be reduced because the solvent used had a boiling point higher than the glass transition temperature of the resin.

[0045]

The heat-resistant resin precursor composition, the method for producing the heat-resistant resin and the heat-resistant resin of the present invention are excellent in electric properties and heat resistance, and are used in various fields where these properties are required. For example, it is a synthetic resin useful as an interlayer insulating film for semiconductors, an interlayer insulating film for multilayer circuits, and the like.

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Claims (6)

[Claims] 1. A heat-resistant resin precursor (A) that generates a heat-resistant resin by a reaction caused by heating, and a heat-resistant resin having a boiling point higher than a temperature at which the heat-resistant resin precursor reacts to form a heat-resistant resin. A heat-resistant resin precursor composition comprising, as an essential component, a solvent (B) lower than the glass transition temperature of the conductive resin. 2. The heat-resistant resin is a polyimide.
The heat-resistant resin precursor composition according to the above. 3. The heat-resistant resin precursor composition according to claim 1, wherein the heat-resistant resin is polybenzoxazole. 4. The heat-resistant resin precursor composition according to claim 2, wherein the heat-resistant resin has a fluorine or fluoroalkyl group. 5. After reacting the heat-resistant resin precursor composition according to any one of claims 1 to 4 at a temperature lower than the boiling point of the solvent (B) in claim 1, to form a heat-resistant resin, A method for producing a heat-resistant resin, comprising a step of performing a heat treatment at a temperature higher than the boiling point of the solvent (B) in claim 1 and lower than the glass transition temperature of the heat-resistant resin. 6. A heat-resistant resin produced by the production method according to claim 5.