KR20180015052A - Copper etching composition and method for fabricating copper interconnection using the same - Google Patents

Abstract

Provided is a copper etching composition which is composed of: an oxidative metal ion; organic acid or inorganic acid; a glycol ether-based compound as a substance to form hydrophobic coating films; and water. Moreover, provided is a copper wiring formation method using the copper etching composition. According to the present invention, the etching composition is capable of preventing side etching on copper wiring.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a copper etching composition and a method for forming copper wiring using the copper etching composition.

The techniques disclosed herein relate to copper etching compositions and methods of forming copper interconnects using them. More particularly, the techniques disclosed herein relate to copper etching compositions that can minimize side etching in copper wiring formation and methods of forming copper wiring using the same.

In the case of forming a copper wiring by a photoetching method in the manufacture of a printed circuit board, that is, a PCB (Printed Circuit Board), an iron chloride based etching solution, a copper chloride based etching solution, an alkaline etching solution and the like are used as an etching solution. When these etchants are used, side etching by isotropic etching occurs. This is a phenomenon in which copper under the photoresist is etched from the side of the wiring pattern. That is, in the portion covered with the photoresist, an unwanted portion (that is, a copper wiring portion) originally etched is removed by the etching solution, and a phenomenon occurs in which the width tapers from the bottom portion to the top portion of the copper wiring do. Particularly, in the case where the copper wiring pattern is fine and the wiring thickness is thick, such a side etching phenomenon becomes remarkable. This phenomenon is likely to cause chip drop due to insufficient junction area during signal transmission or component mounting due to reduction in the circuit width at the top (top) part when forming a fine pattern. In order to prevent this, There is a possibility of causing a short failure between adjacent circuits at the bottom portion. To this end, an etching composition for preventing side etching, a semi additive process (SAP), a modified semi additive process (MSAP) process, and the like have been proposed. However, in the case of the etching composition for preventing the side etching, the etch factor which is a measure thereof is still insufficient (see FIG. 1). In addition, the SAP and MSAP processes require more processing units than the tenting process, which is costly and costly, and the yield is inefficient.

In order to improve the side etching phenomenon of the copper wiring as described above, the Korean Intellectual Property Office 10-2015-0103056 (published September 9, 2015) discloses a 5 to 7 membered aliphatic hetero ring having nitrogen only as a hetero atom constituting the ring Discloses a method of forming an insoluble salt in the form of a protective coating on a side portion of a copper wiring by using a ring compound to lower the side etching. However, there is a problem that an etch factor of 6 or more is not realized, and a process of removing the insoluble salt in the form of a protective film after the formation thereof is required. This can lead to increased process steps and increased process costs and solution stability problems due to impurity formation in the solution. If the protective coating type salt cleaning is incomplete, it may cause voids in the subsequent process, which may cause the yield of the whole process to be lowered.

As another technique for improving the side etching phenomenon, an organic solvent having a viscosity of 0.8 cP or lower and a boiling point of 80 ° C or higher was used in Korean Patent Publication No. 10-2015-0109932 (published on October 2, 2015). Thus, there is a method of suppressing the side etching by decreasing the size of the etchant particles injected from the nozzles and decreasing the side etching rate, and adding weakly coordinated bonds to the metal surface by adding azole compounds containing nitrogen atoms capable of providing electrons Lt; / RTI > This method is also difficult to implement with etch factor 6 or more.

An object of the present invention is to provide an etching composition and a pattern forming method capable of realizing a high etching factor while minimizing side etching of a copper wiring by a tenting method in order to form an efficient fine pattern.

According to an aspect of the present invention, An organic acid or an inorganic acid; a glycol ether-based compound as a hydrophobic film-forming substance; And water.

In one embodiment, the oxidizing metal ion may be selected from a cupric ion or a ferric ion.

In one embodiment, the organic or inorganic acid may be at least one selected from the group consisting of formic acid, acetic acid, oxalic acid, maleic acid, benzoic acid, glycolic acid, sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid.

In one embodiment, the glycol ether compound may be a compound represented by the following formula (1).

[Chemical Formula 1]

Wherein R ₁ is alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, aryl having 6 to 10 carbon atoms or arylalkyl having 7 to 10 carbon atoms, R ₂ is hydrogen or methyl, n is 1 to 100 It is an integer.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: providing a copper metal layer patterned with a resist; Etching the portion of the copper metal layer that is not covered with the resist with a copper etching composition; And forming a copper wiring having an etching factor of 5.5 or more by the etching, wherein the copper etching composition comprises an oxidizing metal ion, an organic acid or an inorganic acid, a glycol ether compound as a hydrophobic film forming material, A wiring forming method is provided.

In one embodiment, the etching with the copper etching composition may be performed by spray spraying.

In the present invention, 'copper' may be made of copper or may be made of a copper alloy. Accordingly, " copper " referred to in this specification refers to copper or a copper alloy.

According to the present invention, it is possible to have a high etching factor and a wide top (circuit) circuit width in realizing a fine pattern of 50 to 80 pitch with an etching composition capable of suppressing the side etching of the copper wiring. Accordingly, it is possible to realize a fine pattern by a tentnig method while reducing a defect rate by short and open.

1 shows a definition of an etching factor value as a parameter indicating a deviation between a bottom portion and a top portion due to the side etching.
FIG. 2 is a schematic view showing the hydrophobic film behavior during etching using the copper etching composition according to an embodiment of the present invention.
FIG. 3 illustrates a 50-pitch copper wiring formed using a copper etching solution according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. The copper etching composition of the present invention is an aqueous solution containing at least one acid and an oxidizing metal ion and a glycol ether compound. The glycol ether compound is used as a hydrophobic film-forming material for suppressing the side etching of the copper wiring.

FIG. 2 is a schematic view showing the hydrophobic film behavior during etching using the copper etching composition according to an embodiment of the present invention. Referring to FIG. 2, in the metal copper layered with the patterned dry film photoresist (DFR), the first hydrophobic coating material forms a film on the copper surface to be etched and is destroyed by the force of the etchant sprayed from the nozzle. This is like a moment when the film is destroyed and re-formed when an impact is applied to the hydrophobic film formed on the water. The etchant permeating through the film thus broken oxidizes the exposed metal copper to form a copper wiring. At this time, since the side portion of the copper wiring is not exposed to the front side of the etching liquid sprayed from the nozzle, the film due to the hydrophobic material is not destroyed, and the side etching is minimized.

Therefore, when forming the copper wiring using the etching composition of the present invention, it is possible to maintain a relatively large top (circuit) width while having a high etching factor. For example, the preferred etch factor may be at least 5.5, preferably at least 6.0, more preferably at least 8.0, even more preferably at least 10.0.

FIG. 3 illustrates a 50-pitch copper wiring formed using a copper etching solution according to an embodiment of the present invention. In (a) without the hydrophobic substance, a circuit width variation between the bottom part and the top part is large, which indicates a low etching factor, and in case (b) including a hydrophobic substance, a high etching factor.

The glycol ether compound used as a hydrophobic film-forming material in the present invention can be represented by the following formula (1).

[Chemical Formula 1]

In the above formula, R ₁ is alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, aryl having 6 to 10 carbon atoms, or arylalkyl having 7 to 10 carbon atoms. Preferably R < ₁ > may be methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, phenyl or benzyl. R ₂ is hydrogen or methyl. And n is an integer of 1 to 100. Typically, n is from 1 to 5.

Specific examples of the glycol ether compound include methyl glycol, methyldiglycol, methyltriglycol, methylpolyglycol, ethylglycol, ethyldiglycol, ethyltriglycol, ethylpolyglycol, butylglycol, butyldiglycol, butyltriglycol, Butyl polyglycol, hexyl diglycol, 2-ethylhexyl glycol, 2-ethylhexyl di (meth) acrylate, It may be at least one member selected from the group consisting of glycol, allyl glycol, phenyl glycol, phenyldiglycol, benzyl glycol, benzyldiglycol, propylpropyleneglycol, propyleneglycol diglycol, butylpropyleneglycol and butylpropyleneglycol.

In a preferred embodiment, the glycol ether compound is selected from the group consisting of methyl glycol, methyldiglycol, methyltriglycol, methylpolyglycol, ethylglycol, ethyldiglycol, ethyltriglycol, ethylpolyglycol, butylglycol, butyldiglycol, Butylene glycol, hexyl diglycol, 2-ethylhexyl glycol, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate, It may be at least two selected from the group consisting of hexyl diglycol, allyl glycol, phenyl glycol, phenyl diglycol, benzyl glycol, benzyl diglycol, propyl propyl diglycol, propyl propyl diglycol, butyl propyl glycol and butyl propyl diglycol. For example, in the case where hexyl diglycol among the above glycol ether compounds is used in combination with other glycol ether compounds such as methyldiglycol, ethyldiglycol, butyldiglycol or butyltriglycol, the etching factor may be further increased. When hexyl diglycol is used alone, the compatibility with the etchant is very low, so that layer separation occurs, so that only a part of the hexyl diglycol prescribed in the composition acts on the hydrophobic film and the effect of increasing the etching factor may be insufficient. On the other hand, when hexyl diglycol is used in combination with other glycol ether compounds such as methyldiglycol, ethyldiglycol, butyldiglycol or butyltriglycol, hexyldiglycol in the etchant is uniformly dispersed in emulsion form without layer separation Any amount prescribed in the composition can act as a hydrophobic coating and contribute to an increase in etch factor.

In the glycol ether compound, a compound having a molecular weight of 90 to 220 g / mol is preferable, and a compound having a molecular weight of 110 to 220 g / mol is preferable from the viewpoint of reduction of side etching. The concentration of the glycol ether compound is preferably 0.1 to 50 g / L, more preferably 0.1 to 40 g / L. When the concentration of the glycol ether compound is less than 0.1 g / L, the hydrophobic film is not sufficiently formed and the side etching suppressing effect may be insufficient. When the concentration is more than 50 g / L, the etching speed is remarkably increased due to the formation of the thick hydrophobic film It can fall.

The acid used in the etching solution of the present invention can be appropriately selected from inorganic acids and organic acids. Specific examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. Specific examples of the organic acid include formic acid (formic acid), acetic acid (acetic acid), oxalic acid, maleic acid, benzoic acid, and glycolic acid. Of these acids, hydrochloric acid is preferable from the viewpoints of the stability of the etching rate and the dissolution stability of copper. The concentration of the acid is preferably 5 to 250 g / L, and more preferably 7 to 230 g / L. When the concentration of the acid is less than 5 g / L, the etching rate is slowed, so that it is impossible to rapidly etch copper, resulting in deterioration of the etching factor as well as mass productivity. When the acid concentration is more than 250 g / L, the working environment may deteriorate and the economy may be lowered. It is preferable that the organic acid or inorganic acid is used in a smaller amount than the oxidizing metal ion because the specific gravity of the etchant is important for forming a hydrophobic coating by using the composition and for instantly etching the coating by spraying force to induce etching in anisotropic manner. The concentration of the oxidizing metal ion having a higher specific gravity is higher than that of the organic acid or inorganic acid having a lower specific gravity, so that a synergistic effect of etching the metal through the hydrophobic film is obtained when the etching solution having a high specific gravity is sprayed by spraying to be.

The oxidizing metal ion used in the etching solution of the present invention is a metal ion capable of oxidizing metal copper, for example, a cupric ion or a ferric ion. From the viewpoint of suppressing the side etching and the stability of the etching rate, it is preferable to use the cupric ion as the oxidizing metal ion. The oxidizing metal ion can be contained in an etching solution as a compound containing an oxidizing metal ion source. For example, when a cupric ion source is used as the oxidizing metal ion source, there may be mentioned copper chloride, copper sulfate, copper bromide, copper salt of organic acid, copper hydroxide and the like. On the other hand, when ferric ions are used as the oxidizing metal ion source, iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, and iron salts of organic acids can be mentioned. The concentration of the oxidizing ions is preferably 10 to 250 g / L, more preferably 10 to 200 g / L. When the concentration of the oxidizing metal ion is less than 10 g / L, the specific gravity of the etching solution is low, so that rapid etching of copper may be difficult due to a decrease in the spraying force. On the other hand, when the concentration of oxidizing metal ions exceeds 250 g / L, precipitation due to supersaturation of copper ions in the etchant may occur, resulting in failure due to substrate reattachment.

According to one embodiment of the present invention, there is provided a copper wiring formation method using the above copper etching composition. The copper wiring forming method may be used when etching a portion of the copper layer not covered with a resist. It is preferable that the etching solution is sprayed by the spraying method when the copper etching composition is etched. This is because the hydrophobic coating on the portion not coated with the resist is broken by the pressure of the etching liquid sprayed from the nozzle as described above, so that the exposed copper metal is etched and the side etching can be minimized while maintaining the hydrophobic coating on the side surface of the copper wiring .

In this case, the nozzle used for spraying is not particularly limited, but a flat type nozzle, a cone type nozzle, or the like can be used. It is also preferable than the spray pressure is 1kg _f or more is preferable, and more than 1.5kg when _f spray etching. If the spray pressure of 1kg _f over contact sufficiently to destroy the hydrophobic film and etching the exposed metal copper can properly form a copper wiring.

Hereinafter, examples of the present invention will be described together with comparative examples. However, the present invention is explained in more detail by the following examples, but the technical idea of the present invention is not limited to the following examples.

[ Example ]

Each of the etching solutions having the compositions shown in Tables 1, 2 and 3 was prepared and evaluated by an evaluation method described later.

First, the sample to be evaluated had a DFR thickness of 20 占 퐉 and a copper thickness of 16 占 퐉, which had been completely developed. The pattern of the sample used was a mixture of several pitches, but the most intricate line / space = 32 占 퐉 / 18 占 퐉 was focused on.

The etching was carried out using a fan type nozzle at a horizontal type spray pressure of 1.8 kgf and a treatment temperature of 50 캜. The etching processing time was set at the time when the width of the bottom of the wiring reached 25 mu m at the pattern L / S = 32 mu m / 18 mu m. Water washing after etching, peeling of the resist, washing with water, and drying.

The side etching amount was measured by cutting a part of the substrate subjected to the etching treatment and observing a cross section of a pattern L / S = 32 mu m / 18 mu m through an optical microscope through molding and polishing. At this time, the etching factor is set to be H / ((W ₂ -W ₁ ) / 2) by using the value of the bottom W ₂ of the wiring, the W ₁ of the wiring, . The results are shown in Tables 1 and 2.

Furtherance Amount of blending Processing
time
(second) Top
Circuit width etching
Factor Example 1 Cupric chloride 450g / L
(170 g / L as cupric ion) 40 19.5 6.1 Hydrochloric acid 200g / L Butyl diglycol 10 g / L Example 2 Cupric chloride 450g / L
(170 g / L as cupric ion) 40 19.7 6.0 Hydrochloric acid 200g / L Butyltriglycol 10 g / L Example 3 Cupric chloride 450g / L
(170 g / L as cupric ion) 50 20.0 6.4 Hydrochloric acid 200g / L Hexyl glycol 10 g / L Example 4 Cupric chloride 450g / L
(170 g / L as cupric ion) 50 20.1 6.6 Hydrochloric acid 200g / L Hexyl diglycol 10 g / L Example 5 Cupric chloride 450g / L
(170 g / L as cupric ion) 40 19.7 6.1 Hydrochloric acid 200g / L Phenylglycol 10 g / L Example 6 Cupric chloride 450g / L
(170 g / L as cupric ion) 40 20.0 6.4 Hydrochloric acid 200g / L Phenyldiglycol 10 g / L

Furtherance Amount of blending Processing
time
(second) Top
Circuit width etching
Factor Comparative Example 1 Ferric chloride 200g / L
(68 g / L in ferric iron) 35 12.2 2.5 Hydrochloric acid 50g / L Comparative Example 2 Ferric chloride 250g / L
(85 g / L in ferric iron) 30 13.9 2.9 Hydrochloric acid 50g / L Comparative Example 3 Cupric chloride 450g / L
(170 g / L as cupric ion) 30 15.0 3.2 Hydrochloric acid 200g / L Comparative Example 4 Cupric chloride 450g / L
(170 g / L as cupric ion) 70 19.0 5.4 Hydrochloric acid 200g / L 1-methylpiperazine 10 g / L Comparative Example 5 Cupric chloride 450g / L
(170 g / L as cupric ion) 45 18.0 4.6 Hydrochloric acid 200g / L 3-aminopyrrolidine 10 g / L Comparative Example 6 Cupric chloride 450g / L
(170 g / L as cupric ion) 45 18.7 5.1 Hydrochloric acid 200g / L 1-methyl homopiperazine 10 g / L

As shown in Table 1, according to the embodiment of the present invention, a relatively wide top (top) circuit width and a high etching factor can be obtained when the above-mentioned glycol ether compound is compounded.

On the other hand, Comparative Examples 4 to 6 were evaluated using a compound known to be effective for suppressing the side etching. As can be seen from the evaluation items, inferior results are obtained compared with the embodiment.

Further, another kind of glycol ether compound was added to the composition of Example 4, and evaluation was carried out by the same method. The results are shown in Table 3 below.

Furtherance Amount of blending Processing
time
(second) Top
Circuit width etching
Factor Example 7 Cupric chloride 200g / L
(68 g / L as cupric ion) 35 21.2 8.4 Hydrochloric acid 50g / L Hexyl diglycol 10 g / L Methyl diglycol 10 g / L Example 8 Cupric chloride 250g / L
(85 g / L as cupric ion) 30 22.1 over 10 Hydrochloric acid 50g / L Hexyl diglycol 10 g / L Ethyl diglycol 10 g / L Example 9 Cupric chloride 250g / L
(85 g / L as cupric ion) 40 21.6 9.4 Hydrochloric acid 200g / L Hexyl diglycol 10 g / L Butyl glycol 10 g / L Example 10 Cupric chloride 250g / L
(85 g / L as cupric ion) 40 21.4 8.9 Hydrochloric acid 200g / L Hexyl diglycol 10 g / L Butyl diglycol 10 g / L Example 11 Cupric chloride 250g / L
(85 g / L as cupric ion) 40 22.0 over 10 Hydrochloric acid 200g / L Hexyl diglycol 10 g / L Butyltriglycol 10 g / L

As shown in Table 3, when two kinds of glycol ether compounds were applied, a broader top circuit width and a higher etching factor were obtained than Example 4. This can maximize the effect of the hydrophobic coating by using two or more kinds of glycol ether compounds having different compatibility with the etching solution. From this result, it is possible to use two or more kinds of glycol ether compounds The side etching can be effectively suppressed.

Claims (9)

Oxidizing metal ions;
Organic or inorganic acids;
Glycol ether-based compounds as hydrophobic film-forming substances; And
Water. ≪ / RTI > The method according to claim 1,
Wherein the oxidizing metal ion is selected from a cupric ion or a ferric ion. The method according to claim 1,
Wherein the organic acid or inorganic acid is at least one selected from the group consisting of formic acid, acetic acid, oxalic acid, maleic acid, benzoic acid, glycolic acid, sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid. The method according to claim 1,
Wherein the glycol ether compound is a compound represented by the following Formula 1:
[Chemical Formula 1]

Wherein R ₁ is alkyl having 1 to 10 carbon atoms, alkenyl having 1 to 10 carbon atoms, aryl having 6 to 10 carbon atoms or arylalkyl having 7 to 10 carbon atoms, R ₂ is hydrogen or methyl, and n is 1 to 100 . The method according to claim 1,
Wherein the glycol ether compound is selected from the group consisting of methyl glycol, methyldiglycol, methyltriglycol, methylpolyglycol, ethylglycol, ethyldiglycol, ethyltriglycol, ethylpolyglycol, butylglycol, butyldiglycol, butyltriglycol, Butylene glycol, 2-ethylhexyl diglycol, 2-ethylhexyl diglycol, 2-ethylhexyl diglycol, isopentyl glycol, isobutyl diglycol, hexyl glycol, hexyl diglycol, Wherein at least one selected from the group consisting of glycol, phenylglycol, phenyldiglycol, benzylglycol, benzyldiglycol, propylpropyleneglycol, propylpropyleneglycol, butylpropyleneglycol and butylpropyleneglycol. The method according to claim 1,
Wherein the glycol ether compound has a molecular weight of 90 to 220 g / mol. The method according to claim 1,
Wherein the concentration of the oxidizing metal ion is 10 to 200 g / L, the organic acid or inorganic acid is 7 to 230 g / L, and the concentration of the glycol ether compound is 0.1 to 50 g / L. Providing a layer of copper metal patterned with a resist;
Etching the portion of the copper metal layer that is not covered with the resist with a copper etching composition; And
And forming a copper wiring having an etching factor of 5.5 or more by the etching,
Wherein the copper etching composition comprises an oxidizing metal ion, an organic acid or an inorganic acid, a glycol ether compound as a hydrophobic film forming material, and water. The method according to claim 1,
Wherein the etching with the copper etching composition is performed by spray spraying.

Images