Cleaning solution for simultaneously removing photoresist residue and etch stop layer, and method for manufacturing semiconductor circuit element using same

Abstract

According to the present invention, it is possible to provide a cleaning solution for simultaneously removing a photoresist film or residue generated after a photoresist ashing process and aluminum oxide, which is an etch stop layer, in a process for forming metal traces on a board, the cleaning solution containing at least one organic alkali selected from the group consisting of amines or quaternary ammonium hydroxides, and at least one organic solvent (except dimethyl sulfoxide), in which the concentration of the amines is between 0.1% and 25% by mass of the total mass of the cleaning solution or the concentration of the quaternary ammonium hydroxides is between 0.05% and 0.5% by mass of the total mass of the cleaning solution.

Description

Cleaning solution for simultaneously removing photoresist residue and etching stopper layer and method for manufacturing semiconductor circuit element using the same

[0001] The present invention relates to a cleaning solution that simultaneously removes a photoresist film or residues generated after ashing of the photoresist, and aluminum oxide, which serves as a dry etching stopper layer, in a process for forming metal wiring on a substrate, and a method for manufacturing a semiconductor circuit element using the same.

[0002] Dry etching is a process used in the manufacturing of semiconductor substrates, and involves selectively removing certain materials from other materials. During this process, dry etching residues, such as undissolved etching residues and metal shavings, remain on the surface after the etching process, and cleaning solutions are used to remove these.

[0003] Semiconductor substrates often contain a dry etching stopper layer, such as aluminum oxide, to prevent damage to the wiring material caused by dry etching. Cleaning technology is needed to remove dry etching residues and the dry etching stopper layer while protecting the substrate's wiring material and interlayer insulating film. Furthermore, it is necessary to suppress side etching of the dry etching stopper layer, such as aluminum oxide, which is an undesirable phenomenon in the film formation process after cleaning.

[0004] Oxidizing and reducing agents are sometimes used in cleaning solutions to weaken dry etching residues. However, these agents can cause performance degradation due to component decomposition in the cleaning solution and can also cause changes in the material properties of the substrate surface. Anticorrosive agents are also sometimes used to prevent damage to the wiring material, but any anticorrosive agents adsorbed on the wiring material surface must be removed to prevent problems in the film formation process after cleaning.

[0005] In this situation, Patent Document 1 describes a resist stripping composition containing tetramethylammonium hydroxide, acetonitrile, dimethyl sulfoxide, and water. Dimethyl sulfoxide is the most frequently used solvent, but it is not satisfactory in terms of removability of photoresist films or residues generated after ashing of photoresists.

[0006] JP 2008-3291 A

[0007] The problem to be solved by the present invention is to provide a cleaning solution that can prevent corrosion of metal wiring and interlayer insulating films and simultaneously remove photoresist films or residues and etching stopper layers generated after ashing of photoresists, which have been difficult to achieve with conventional methods, and a method for manufacturing semiconductor circuit elements using the same.

[0008] As a result of extensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a cleaning solution containing specific amounts of at least one organic alkali selected from the group consisting of amines and quaternary ammonium hydroxides, and at least one organic solvent (excluding dimethyl sulfoxide).

[0009] <1> A cleaning solution for simultaneously removing a photoresist film or a residue generated after ashing of the photoresist, and an aluminum oxide etching stopper layer, in a step of forming metal wiring on a substrate, the cleaning solution comprising at least one organic alkali selected from the group consisting of amines and quaternary ammonium hydroxides, and at least one organic solvent (excluding dimethyl sulfoxide), wherein the concentration of the amines is 0.1% by mass to 25% by mass, relative to the total mass of the cleaning solution, or the concentration of the quaternary ammonium hydroxide is 0.05% by mass to 0.5% by mass, relative to the total mass of the cleaning solution. <2> The cleaning solution according to <1> above, wherein the amine or the quaternary ammonium hydroxide is one or more selected from the group consisting of 2-(methylamino)ethanol, 2-(ethylamino)ethanol, N,N-bis(3-aminopropyl)ethylenediamine, 3,3-diaminodipropylamine, ethylenediamine, diethylenetriamine, 4-amino-1-butanol, 6-amino-1-hexanol, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. <3> The cleaning solution according to <1> or <2> above, wherein the organic solvent is one or more selected from the group consisting of glycol ethers, acetonitrile, and acetone. <4> The cleaning solution according to <3> above, wherein the glycol ether is one or more selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, and diethylene glycol monohexyl ether. <5> The cleaning solution according to any one of <1> to <4> above, wherein the concentration of the amines is 0.3% by mass to 10% by mass, or the concentration of the quaternary ammonium hydroxide is 0.1% by mass to 0.4% by mass, relative to the total mass of the cleaning solution. <6> The cleaning solution according to any one of <1> to <5> above, wherein the concentration of the organic solvent is 45% by mass to 85% by mass, relative to the total mass of the cleaning solution. <7> The cleaning solution according to any one of <1> to <6> above, wherein the pH of the cleaning solution is in the range of 8 to 13.<8> A method for producing a semiconductor circuit element, comprising the step of removing photoresist or photoresist residues after ashing using the cleaning solution according to any one of <1> to <7> above.

[0010] According to the present invention, it is possible to provide a cleaning solution capable of simultaneously removing a photoresist film or residues generated after ashing of the photoresist, and aluminum oxide, which serves as an etching stopper layer, in a process of forming metal wiring on a substrate, and a method for manufacturing a semiconductor circuit element using the same.

[0011] 1 is a schematic diagram showing the simultaneous removal of a photoresist film and aluminum oxide, which is an etching stopper layer, using the cleaning solution of the present invention, and FIG. 2 is a schematic diagram showing the simultaneous removal of residues generated after ashing of the photoresist and aluminum oxide, which is an etching stopper layer, using the cleaning solution of the present invention.

[0012] The cleaning solution of the present invention simultaneously removes a photoresist film or photoresist residue generated after ashing and an aluminum oxide etching stopper layer during the process of forming metal wiring on a substrate. FIG. 1 shows the simultaneous removal of a photoresist film 20A and an exposed AlOx etching stopper layer 30 by the cleaning solution of the present invention. FIG. 2 shows the simultaneous removal of a photoresist residue 20B after ashing and an exposed AlOx etching stopper layer 30 by the cleaning solution of the present invention. Meanwhile, as shown in FIGS. 1 and 2, the cleaning solution of the present invention does not damage the interlayer insulating film 40, the AlOx etching stopper layer 30 sandwiched between the interlayer insulating films 40, or the metal wiring 10. The cleaning solution of the present invention contains at least one organic alkali selected from the group consisting of amines or quaternary ammonium hydroxides, and at least one organic solvent (excluding dimethyl sulfoxide). A detailed description is provided below.

[0013] [Amines or Quaternary Ammonium Hydroxides] The amines or quaternary ammonium hydroxides used in the present invention are not particularly limited as long as they can simultaneously remove the photoresist film or residues generated after ashing of the photoresist, and the aluminum oxide etching stopper layer. However, they are preferably one or more selected from the group consisting of 2-(methylamino)ethanol, 2-(ethylamino)ethanol, N,N-bis(3-aminopropyl)ethylenediamine, 3,3-diaminodipropylamine, ethylenediamine, diethylenetriamine, 4-amino-1-butanol, 6-amino-1-hexanol, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. 2-(methylamino)ethanol, 2-(ethylamino)ethanol, and tetramethylammonium hydroxide are more preferred, and 2-(methylamino)ethanol is particularly preferred. These organic alkalis may be used alone or in combination of two or more. These organic alkalis are readily available commercially and can be used advantageously.

[0014] The concentration of the amines is 0.1% by mass to 25% by mass, preferably 0.2% by mass to 20% by mass, and more preferably 0.3% by mass to 10% by mass, based on the total mass of the cleaning solution. The concentration of the quaternary ammonium hydroxide is 0.05% by mass to 0.5% by mass, preferably 0.08% by mass to 0.45% by mass, and more preferably 0.1% by mass to 0.4% by mass, based on the total mass of the cleaning solution. By using the organic alkali in these ranges, both the removability of the residue generated after the ashing process of the photoresist film or photoresist and the removability of the aluminum oxide-containing etching stopper layer can be achieved. If the amount of organic alkali used is too high, the removability of the aluminum oxide-containing etching stopper layer increases, resulting in increased side etching of the aluminum oxide-containing etching stopper layer. On the other hand, if the amount of organic alkali used is too low, the removability of the residue generated after the ashing process of the photoresist film or photoresist and the aluminum oxide-containing etching stopper layer will be insufficient.

[0015] [Organic Solvent] The organic solvent used in the present invention is not particularly limited as long as it can remove the photoresist film or residues generated after the ashing treatment of the photoresist while suppressing the removal of the aluminum oxide etching stopper layer (excluding dimethyl sulfoxide), but is preferably at least one selected from the group consisting of glycol ethers, acetonitrile, and acetone. Specifically, the glycol ether is preferably at least one selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, and diethylene glycol monohexyl ether, with diethylene glycol monobutyl ether being particularly preferred. These organic solvents may be used alone or in combination of two or more. These organic solvents are readily available commercially and can be used suitably.

[0016] The concentration of the organic solvent is preferably 45% by mass to 85% by mass, more preferably 50% by mass to 80% by mass, and particularly preferably 55% by mass to 75% by mass, based on the total mass of the cleaning solution. If the amount of organic solvent used is too small, the removability of the etching stopper layer containing aluminum oxide may increase, resulting in increased side etching of the etching stopper layer containing aluminum oxide. Furthermore, the corrosion resistance of the metal wiring may also be insufficient. On the other hand, if the amount of organic solvent used is too large, the removability of the etching stopper layer containing aluminum oxide may decrease, resulting in a longer cleaning time.

[0017] [Water] The cleaning solution of the present invention contains water in addition to the amines or quaternary ammonium hydroxide and the organic solvent. The water used in the present invention is not particularly limited and may be tap water, industrial water, groundwater, distilled water, ion-exchanged water, or ultrapure water, but is preferably ion-exchanged water, and more preferably ultrapure water. The water content in the cleaning solution is preferably in the range of 10 to 70% by mass, and more preferably in the range of 15 to 60% by mass.

[0018] [Cleaning Solution] The cleaning solution of the present invention can be prepared by uniformly stirring amines or quaternary ammonium hydroxide, an organic solvent, and water using a conventional method. The cleaning solution of the present invention may contain other components in addition to those described above, such as a metal wiring anticorrosion agent. Anticorrosion agents are not particularly limited, but azoles are preferred. The pH of the cleaning solution is preferably 8 to 13, more preferably 9 to 12. If the pH is too low, the removability of the aluminum oxide-containing etching stopper layer and the corrosion protection of the metal wiring may decrease. If the pH is too high, the removability of the aluminum oxide-containing etching stopper layer may increase, resulting in increased side etching of the aluminum oxide-containing etching stopper layer. The pH may be adjusted solely by the content of amines or quaternary ammonium hydroxide, or an acid may be added within a range that does not impair the objectives of the present invention.

[0019] [Semiconductor Circuit Element] A semiconductor circuit element for which the cleaning solution of the present invention is used preferably has metal wiring, an interlayer insulating film, and an etching stopper layer, and has a photoresist film or photoresist residue after ashing on the interlayer insulating film. The interlayer insulating film may also contain a low-dielectric constant film (Low-k film). The etching stopper layer preferably contains aluminum oxide.

[0020] [Method for Manufacturing Semiconductor Circuit Element] The method for manufacturing a semiconductor circuit element of the present invention includes a step of removing photoresist residues after ashing using the cleaning solution of the present invention. For example, the cleaning solution of the present invention can be used for immersion treatment or single-wafer treatment on semiconductor circuit elements after etching treatment. The treatment temperature is usually 20 to 80°C, preferably 30 to 65°C. The treatment time is usually 0.5 to 5 minutes, preferably 1 to 3 minutes. As a rinse solution after using the cleaning solution of the present invention, rinsing with water is often sufficient, but organic solvents such as alcohol or aqueous ammonia may also be used.

[0021] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples in any way.

[0022] [Examples 1 to 26 and Comparative Examples 1 to 4] Cleaning solutions were prepared with the compositions shown in Tables 1 and 2 below. The balance was water. The concentrations in Tables 1 and 2 are expressed in mass %.

[0023]

[0024]

[0025] For each blanket wafer, AlOx (PVD sputtering deposition, film thickness 3,000 Å), positive resist (novolac resist, film thickness 7,500 Å), and negative resist (acrylic resist, film thickness 7,500 Å) were each cut into 1 cm squares, and these coupons were immersed in 10 g of each of the above cleaning solutions at 60°C while stirring with a stirrer. The immersion time was 2 minutes for AlOx and 9 seconds for each resist. After immersion, the coupons were rinsed twice by moving them in approximately 100 g of ultrapure water (UPW) at room temperature for 10 seconds, and then rinsed with N ２ The coupon was blow dried.

[0026] <Assessment of AlOx Removal Ability> The Al ion concentration in the cleaning solution in which the AlOx coupon was immersed was measured using an ICP-OES (5110 manufactured by Agilent). The film thickness (Å) of the dissolved AlOx was calculated from the concentration, and the etching rate (Å / min) was calculated by dividing this by the coupon treatment time of 2 minutes. An etching rate in the range of 6 to 40 Å / min was rated as "good," and an etching rate greater than 40 Å / min was rated as "excessive." The results are shown in Tables 1 and 2.

[0027] <Judgment of Resist Removability> The coupons after 9 seconds of treatment were visually inspected, and if 95% or more of the base was visible on the coupon area, the removability was rated as "good," and if not, the removability was rated as "poor." The results are shown in Tables 1 and 2.

[0028] <pH Measurement of Cleaning Solutions> A FiveEasy pH meter FE20 manufactured by Mettler Toledo was used as the pH meter, and an LE409 pH electrode manufactured by the same company was used. After calibration using standard samples of pH 7 and pH 10, the pH of each cleaning solution was measured. The results are shown in Tables 1 and 2.

[0029] 10: Metal wiring 20A: Photoresist film 20B: Photoresist residue after ashing 30: AlOx etching stopper layer 40: Interlayer insulating film

Claims

1. A cleaning solution for simultaneously removing a photoresist film or a residue generated after ashing of the photoresist, and an aluminum oxide etching stopper layer, in a process for forming metal wiring on a substrate, the cleaning solution containing at least one organic alkali selected from the group consisting of amines or quaternary ammonium hydroxides, and at least one organic solvent (excluding dimethylsulfoxide), the concentration of the amines being 0.1% by mass to 25% by mass relative to the total mass of the cleaning solution, or the concentration of the quaternary ammonium hydroxide being 0.05% by mass to 0.5% by mass relative to the total mass of the cleaning solution.

2. The cleaning solution according to claim 1, wherein the amines or the quaternary ammonium hydroxide are one or more selected from the group consisting of 2-(methylamino)ethanol, 2-(ethylamino)ethanol, N,N-bis(3-aminopropyl)ethylenediamine, 3,3-diaminodipropylamine, ethylenediamine, diethylenetriamine, 4-amino-1-butanol, 6-amino-1-hexanol, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

3. The cleaning solution according to claim 1 or 2, wherein the organic solvent is at least one selected from the group consisting of glycol ethers, acetonitrile, and acetone.

4. The cleaning solution according to claim 3, wherein the glycol ether is at least one selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, and diethylene glycol monohexyl ether.

5. The cleaning solution according to any one of claims 1 to 4, wherein a concentration of the amines is 0.3 mass % to 10 mass % relative to the total mass of the cleaning solution, or a concentration of the quaternary ammonium hydroxide is 0.1 mass % to 0.4 mass % relative to the total mass of the cleaning solution.

6. A cleaning solution according to any one of claims 1 to 5, wherein the concentration of the organic solvent is 45% by mass to 85% by mass based on the total mass of the cleaning solution.

7. The cleaning solution according to any one of claims 1 to 6, wherein the pH of the cleaning solution is in the range of 8 to 13.

8. A method for manufacturing a semiconductor circuit element, comprising the step of removing photoresist or photoresist residues after ashing using the cleaning solution according to any one of claims 1 to 7.