KR20110077734A - Etching solution composition and manufacturing method of semiconductor device using same - Google Patents

Abstract

The present invention relates to an etchant composition and a method for manufacturing a semiconductor device using the same, specifically, the etchant composition of the present invention is 0.5 to 2% by volume sulfuric acid; 0.5 to 5% by volume phosphoric acid; 0.1 to 1% by volume of weak acid having an acid dissociation constant (pKa) of 3.0 or more; 0.01 to 0.1 volume percent hydrogen peroxide; And the balance of pure water.

The etchant composition of the present invention can control the etching rate, improve the uniformity of the etching target layer, and can minimize the influence on the surrounding materials other than the etching target layer can be usefully used for wet etching during the semiconductor manufacturing process.

Etch, Acid Dissociation Constant, Etch Rate

Description

Etching solution composition and manufacturing method of semiconductor device using same

The present invention relates to an etching solution composition and a method for manufacturing a semiconductor device using the same, and specifically, the etching rate can be controlled, the uniformity of the etching target layer can be improved, and the influence on the surrounding materials other than the etching target layer can be minimized. The present invention relates to an etchant composition that can be used for wet etching in a semiconductor manufacturing process, and a method of manufacturing a semiconductor device using the same.

In general, a semiconductor device is formed by performing a series of processes such as a deposition process, a photo process, an etching process, and an ion implantation process. That is, a semiconductor device is formed by depositing a plurality of semiconductor thin films, such as a polycrystalline film, a silicide film, an oxide film, a nitride film and a metal film, on a wafer to form a pattern through a photo process and an etching process. Therefore, since the semiconductor device must form a pattern on various types of polycrystalline film, silicide film, oxide film, nitride film, and metal film, an etchant composition for effectively removing the films according to the various types is very important.

In addition, an etching process is also included in the wiring process, the removal of the seed metal layer, and the like during the semiconductor device manufacturing process, and an etching solution composition containing sulfuric acid or phosphoric acid and hydrogen peroxide is used.

In the wet etching process using the etchant composition, a single type of etching, a batch type etching, or a dip type etching method may be used. Among them, the dip type etching method is the best in terms of uniformity and cost. However, when the dip type etching is performed with an etching solution composition containing sulfuric acid or phosphoric acid, the etching rate is different depending on the flow direction of the etching solution, so that the etching does not occur uniformly. There is a problem appearing.

An object of the present invention to control the above problems, it is possible to control the etching rate, the etching speed is uniform in the entire etching layer to improve the uniformity of the etching layer, and to minimize the influence on the surrounding material other than the etching layer The present invention provides an etchant composition that can be used for wet etching in a semiconductor manufacturing process, and a method for manufacturing a semiconductor device using the same.

The present invention to achieve the above object,

Sulfuric acid 0.5-2% by volume;

0.5 to 5% by volume phosphoric acid;

0.1 to 1% by volume of weak acid having an acid dissociation constant (pKa) of 3.0 or more;

0.01 to 0.1 volume percent hydrogen peroxide; And

It provides an etchant composition comprising the remainder of the pure water.

The weak acid may be acetic acid.

The etchant composition may be used in a dip type etching process.

The present invention to achieve another object of the present invention,

A seed layer forming step of depositing a metal on one surface of the substrate;

A pattern forming step of coating a photoresist on the seed layer and forming a photoresist pattern through an exposure and development process;

A filler forming step of forming a pillar by injecting a metal into an upper surface of the exposed seed layer not coated with the photoresist;

A removal step of removing the photoresist except the filler; And

Etching step of removing the seed layer on the lower surface of the photoresist removed in the removal step except for the filler using the etching solution composition of the present invention A method for manufacturing a semiconductor device is provided.

The method may further include a solder layer forming step of forming a solder layer on an upper surface of the filler after the filler forming step.

The seed layer and the filler may be formed of copper.

The solder layer may be formed of lead, tin, or an alloy thereof.

The etching may be performed for 30 seconds to 90 seconds.

When using the etching solution composition of the present invention in the etching process it is possible to control the etching rate. Therefore, the variation of the etching speed according to the flow direction of the etchant in the etching layer can be reduced, so that the etching can be performed more uniformly over the entire etching layer.

The etchant composition of the present invention can minimize the influence on the peripheral region other than the etching layer.

In particular, in the process of removing the seed layer during the semiconductor device manufacturing process, there is no excessive dissolution of the filler, and only the seed layer is selectively etched and the solder layer is not dissolved, thereby obtaining a uniform etching profile.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily practice.

First, the etching liquid composition of this invention is demonstrated.

The etchant composition of the present invention comprises sulfuric acid (H ₂ SO ₄ ).

Sulfuric acid (H ₂ SO ₄ ) is the main component to perform the etching is accelerated by the sulfuric acid etching rate. The sulfuric acid is a strong acid present in a completely ionized state in an aqueous solution, and dissociates in the aqueous solution as in Scheme 1 below.

Scheme 1

^{_{H 2 SO 4 → 2H + +}} SO 4 2 -

The etching proceeds due to the reaction between the sulfate ion and the metal formed by the dissociation reaction of sulfuric acid.

The sulfuric acid may be included in 0.5 to 2% by volume based on the etching solution composition. When the sulfuric acid is included in less than 0.5% by volume, the etching rate is too slow, and uneven etching and damage to the filler may occur. Even when the sulfuric acid is contained in more than 2% by volume, the etching rate is too fast, so that etching is performed on the front of the wafer. May not occur uniformly across.

The etchant composition of the present invention comprises phosphoric acid (H ₃ PO ₄ ).

The phosphoric acid belongs to a strong acid, most of which is present in an ionized form in aqueous solution, but serves as a weak acid rather than the sulfuric acid to inhibit the strong reaction between sulfate and metal ions.

The phosphoric acid is dissociated in an aqueous solution as in Scheme 2 below, and the acid dissociation constant (pKa) of phosphoric acid is 2.16.

Scheme 2

H ₃ PO _{4 ^{→ H + + H 2 PO 4}} 2 -

The etching proceeds while the phosphate ions formed by the dissociation reaction of the phosphoric acid react with the metal.

The phosphoric acid may be included in an amount of 0.5 to 5% by volume based on the etching solution composition. If phosphoric acid is included in less than 0.5% by volume it may not be completely etched to the desired area, when contained in more than 5% by volume it may be difficult to uniformly etch the etching rate is fast.

The etchant composition of the present invention includes a weak acid having an acid dissociation constant (pKa) of 3.0 or more in addition to the sulfuric acid and phosphoric acid.

The weak acid is a weak acid having an acid dissociation constant greater than that of phosphoric acid. As the concentration of the acid decreases, the dissociation degree increases. The stronger acid is dissociated first, and the weaker acid is dissociated after strong acid dissociation, so that the weak acid is dissociated after dissociation of sulfuric acid or phosphoric acid, which is strong, so that the etching layer is uniformly etched, and the etching rate is prevented by preventing excessive etching at the initial stage of etching. It has a role to control.

The acid dissociation constant is the ionization equilibrium constant of the acid.It is a measure of the strength of the acid.For strong acids, the total acidity is completely ionized in aqueous solution, and for weak acids, it is only partially ionized. And the pKa value decreases. In addition, the degree of dissociation of the weak acid increases as the concentration decreases. Therefore, when the etching target layer is first divided into the first region, the second region, and the third region according to the flow direction of the etching composition, the sulfuric acid, which is a strong acid, is the highest in the first region of the etching layer. Dissociates to generate hydrogen ions, and in the second region, the concentration of sulfuric acid is diluted according to the flow direction of the etchant composition, so that dissociation of phosphoric acid, which is weaker than sulfuric acid, is increased, and phosphoric acid generates hydrogen ions, and acid dissociation in the third region. The dissociation degree of weak acid with a constant of 3.0 or higher is the highest, and the weak acid generates hydrogen ions.

Preferably, acetic acid may be used as the weak acid. The acetic acid is a weak acid which exists only in an ionized form in an aqueous phase, and is dissociated as in Scheme 3 below, and the acid dissociation constant is 4.76.

Scheme 3

^{_{CH 3 COOH → H + + CH}} 3 COO -

FIG. 1 shows the dissociation degree of sulfuric acid, phosphoric acid and acetic acid on the upper surface of the wafer according to the flow direction of the etching liquid in the etching liquid composition containing sulfuric acid, phosphoric acid and acetic acid. Referring to FIG. 1, the dissociation degree of sulfuric acid, which is a strong acid, is high in the first region of the upper surface of the wafer, and the dissociation degree of phosphoric acid, which is weaker than sulfuric acid, is increased in the second region, which is the middle region of the wafer, as the etching liquid composition flows. It can be seen that the dissociation degree of acetic acid, which is weaker than phosphoric acid, increases in the third region. This is expected to be due to the decrease in acid concentration in the composition as the etching proceeds according to the flow direction of the etchant composition, and as the concentration decreases, the dissociation degree of the weak acid increases. As shown in FIG. 1, the dissociated acid varies according to each region of the upper surface of the wafer, and when the sulfuric acid, phosphoric acid, and acetic acid are mixed, the concentration of hydrogen ions remains uniform and the etching is uniform. It can be seen that. In addition, the uniformity of the etching may be improved by preventing dissociation of all acids in the first region and excessively increasing the etching rate.

The weak acid having an acid dissociation constant of 3.0 or more may be included in an amount of 0.1 to 1% by volume based on the composition. When the weak acid is included in less than 0.1% by volume, the amount of the weak acid dissociated after dissociation of the strong acid may not occur uniformly, and when included in more than 1% by volume, the etching effect of sulfuric acid and phosphoric acid is reduced to reduce the etching. The uniformity of can be reduced.

The etchant composition of the present invention includes hydrogen peroxide (H ₂ O ₂ ) in addition to the acid.

The hydrogen peroxide is a component used as an oxidant, and serves to oxidize and etch an etching target layer.

The hydrogen peroxide may be included in an amount of 0.01 to 0.1% by volume based on the etching solution composition. When the hydrogen peroxide is included in less than 0.01% by volume, the etching rate may be lowered and may cause a poor etching profile. When the hydrogen peroxide is included in an amount exceeding 0.1% by volume, the etching may proceed excessively and may be etched to the surrounding area outside the etching layer. And the etching profile may not be uniform.

The etchant composition of the present invention contains the remainder of pure water (H ₂ O) in addition to the above components, in addition to the above-mentioned components in accordance with the needs of those skilled in the art within the scope of not impairing the object of the present invention, for example, surfactants It may further include a metal ion sequestrant and a corrosion inhibitor.

The etchant composition of the present invention can be used for dip type wet etching. The etchant composition may be applied to conventional wet etching known in the art, and preferably may be applied to a dip type etching process.

2 is a schematic diagram showing a dip type etching process and an etching rate according to an etchant flow direction at this time. According to FIG. 2, in the dip type etching process, the wafer is vertically introduced into the etching chamber, and etching is performed simultaneously with stirring. At this time, the etching proceeds at a high speed from a portion in contact with the inlet of the etchant composition, and the etching rate decreases as the etching proceeds according to the flow direction of the composition of the etchant. The etching rate in the dip type etching can be expressed by the following Equation 1:

[Equation 1]

Etch Rate = kNe ^{- hx}

(Where k is a function of temperature and activation energy, and h is a function of molar concentration and Gibbs energy of hydrogen ions.)

The etchant composition of the present invention maintains a relatively uniform concentration of hydrogen ions in the etched layer, thereby reducing the h, thereby obtaining a more uniform etching profile.

Hereinafter, the manufacturing method of the semiconductor device using the etching liquid composition of this invention is demonstrated.

FIG. 3 is a schematic diagram schematically illustrating a method of manufacturing a semiconductor device using the etchant composition according to an embodiment of the present invention according to a process sequence. FIG. Referring to FIG. 3, a method of manufacturing a semiconductor device of the present invention includes a seed layer forming step; Pattern forming step; Filler forming step; A removal step and an etching step. In addition, the method may further include forming a solder layer. Since the etching solution composition of the present invention is used in the etching step, the uniformity of the etching profile may be improved.

The seed layer forming step is to deposit a metal on one surface of the substrate.

The lamination method of the metal can be used without limitation methods known in the art such as vapor deposition, the metal may preferably be used copper. Copper has excellent electrical conductivity, is easy to deposit and etch, and has a high dielectric constant, which is widely used as a material for metal wiring during semiconductor manufacturing processes.

The pattern forming step is a step of forming a photoresist pattern by coating a photoresist on the top surface of the seed layer and through an exposure and development process.

Specifically, a desired photoresist pattern is formed through a lithography process in which a photoresist is coated on an upper surface of the seed layer using a method known in the art such as spin coating, a mask is arranged on an upper surface of the photoresist, and then exposed and developed. Forming.

The filler forming step is to form a metal pillar on the top surface of the exposed seed layer not coated with the photoresist.

The metal filler may be formed using a method known in the art, and preferably, may be formed by a deposition process or an electroplating process used in a semiconductor process, and may have a shape such as a cylinder or a square column having a predetermined height. Can be formed.

The metal filler may be formed of a metal having good electrical conductivity while having a certain strength, such as copper or a copper alloy, but is not limited thereto.

The solder layer forming step is a step in which a solder layer is coated to a predetermined thickness on an upper surface of the filler. The solder layer serves to facilitate adhesion of the metal filler to the LTCC substrate. The solder layer may be formed of a metal having a low melting point such as copper, tin, or an alloy thereof, but is not limited thereto.

The removing step is to remove the photoresist except the filler. Removal of the photoresist may be performed using a method known in the art, specifically, the photoresist may be removed by immersing in an organic solvent for photoresist etching at room temperature for 2 to 5 minutes. The organic solvent can be used without limitation those known in the art.

The etching step is to remove the seed layer located on the lower surface of the photoresist removed in the removal step except for the filler using the etching solution composition of the present invention. When using the etchant composition of the present invention in the etching step it is possible to obtain a uniform etching profile while minimizing the influence on the filler and solder layer already formed.

The etching may use a wet etching method known in the art, but may preferably use a dip type etching process. Specifically, after the wafer in which the filler is formed is placed in a chamber filled with the etchant composition of the present invention, only the seed layer except for the filler may be removed by stirring the wafer or the etchant. In addition, the etching may be performed for 30 seconds to 90 seconds, the same process may be repeated several times depending on the thickness of the seed layer. When etching is performed in less than 30 seconds, the seed layer may not be completely removed, and when the etching is performed in excess of 90 seconds, the seed layer may be etched up to the metal filler or the solder layer.

A semiconductor device may be manufactured through the above process, and specifically, a filler of the semiconductor device may be manufactured.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. This is for the purpose of illustrating the invention only, and thus the scope of the invention is not limited.

< Example  1 and 2 and Comparative example  1 to 2> Etchant  Preparation of the composition

To prepare an etchant composition by the method known in the art in the composition of Table 1. The units in Table 1 below are volume percent.

Furtherance Example 1 Example 2 Comparative Example 1 Comparative Example 2 Sulfuric acid (H ₂ SO ₄ ) 0.96 0.96 0.96 0.96 Phosphoric Acid (H ₃ PO ₄ ) 1.7 1.7 - 1.7 Acetic acid (CH ₃ COOH) 0.3 0.1 - - Hydrogen Peroxide (H ₂ O ₂ ) 0.03 0.03 0.03 0.03 Pure water (H ₂ O) 97.01 97.21 99.01 97.31

< Example  3> Example 1 of Etchant  Copper with the composition Of filler  Produce

Copper was coated on the upper surface of the silicon wafer to form a seed layer, and a photoresist pattern was formed on the upper surface of the copper seed layer by a lithography process, and then copper was injected by electroplating to form a copper filler. Subsequently, an alloy of tin and lead was coated on the upper surface of the copper filler to form a solder layer, and the photoresist was removed after forming the copper filler and the solder layer. In order to remove the copper seed layer coated on the upper surface of the wafer, the wafer was etched with the etchant composition of Example 1 for about 70 seconds using a deep etching apparatus as shown in FIG. 4.

< Example  4> Example 2 of Etchant  Copper with the composition Of filler  Produce

A copper filler was prepared in the same manner as in Example 1, except that the etching solution composition of Example 2 was etched for about 70 seconds.

< Comparative example  3> Comparative example 1 of Etchant  Copper with the composition Of filler  Produce

A copper filler was prepared in the same manner as in Example 3, except that the etching solution composition of Comparative Example 1 was etched for about 50 seconds.

< Comparative example  4> Comparative example 2 of Etchant  Copper with the composition Of filler  Produce

A copper filler was prepared in the same manner as in Example 3, except that the etching solution composition of Comparative Example 2 was etched for about 50 seconds.

< Experimental Example  1> Etched  Trend comparison

Copper was coated on the upper surface of the silicon wafer, and dip etching was performed for 40 seconds to 60 seconds using the etching solution compositions prepared in Examples 1 and Comparative Examples 1 to 2 to examine the tendency of etching. The result is shown in FIG.

Referring to FIG. 5, in the case of etching with the etchant compositions of Comparative Examples 1 and 2 not containing acetic acid, after 20 seconds, the first region, which first comes into contact with the etchant composition, is first etched, and the second and third regions are less etched with copper. It can be seen that the remaining phenomenon is observed. On the other hand, when using the etchant composition of the example was slower than the etching rate, it can be seen that the etching proceeds uniformly as a whole.

< Experimental Example  2> After etching  Copper Of filler  observe

After etching the copper fillers prepared in Examples 3 to 4 and Comparative Examples 3 to 4 were observed, the results are shown in FIG. 6.

6, the side of the copper filler was etched about 0.5 μm to 1 μm in Example 3 etched with the etchant composition of Example 1, but in Comparative Example 4 etched with the etchant composition of Comparative Example 2 It is etched about 1.0 ㎛ to 1.5 ㎛ it can be seen that the etching liquid composition of the comparative example has a greater effect on the copper filler than the composition of the example. In addition, in the case of the filler of Comparative Example 3 etched with the composition of Comparative Example 1, the filler of the top portion showed a tendency to be etched to the solder layer.

As a result, the filler of Examples 3 and 4 etched with the etchant compositions of Examples 1 and 2 had a small effect on the copper filler, but the copper of Comparative Examples 3 and 4 etched with the etchant compositions of Comparative Examples 1 and 2 In the case of the filler, the copper filler was etched to have a thinner thickness than that of the example, and the filler was etched up to the solder layer.

< Experimental Example  3> Etchant  Along the flow Etching  Measure of speed

When copper is coated on the silicon wafer and the etching process is performed with the etchant compositions of Example 1 and Comparative Examples 1 to 2, the etching rate is measured and the results are shown in FIG. 7.

Referring to FIG. 7, in the etching liquid composition of Comparative Example 1, the etching speed was high in the first region of the wafer contacting the etching solution, but the etching rate was decreased according to the flow direction of the etching solution, and the variation was large. On the other hand, in the case of the etchant composition of Example 1 it can be seen that the etching rate is more uniform than the etchant composition of the comparative example over the entire wafer.

As described above, the etching liquid composition of the present invention uses a mixture of acids having different acid dissociation constants at a predetermined ratio, so that the etching rate in the etching layer is uniform and the etching rate can be controlled to obtain a uniform etching profile. It can be seen that the effect on other parts besides the etching layer is minimized.

FIG. 1 shows the dissociation of sulfuric acid, phosphoric acid and acetic acid on the upper surface of the wafer along the flow direction of the etchant composition comprising sulfuric acid, phosphoric acid and acetic acid.

Figure 2 shows a schematic diagram showing a dip type etching process and the etching rate according to the flow direction of the etchant composition at this time.

FIG. 3 is a schematic diagram schematically illustrating a method of manufacturing a semiconductor device using the etchant composition according to an embodiment of the present invention according to a process sequence. FIG.

4 illustrates a dip etching apparatus used in an embodiment of the present invention.

Figure 5 shows the etching tendency after the deep etching on the copper-coated wafer with the compositions of Examples and Comparative Examples of the present invention.

6 shows a copper filler prepared by etching with the etchant composition of Examples and Comparative Examples of the present invention.

Figure 7 shows the etching rate when using the etching liquid composition of the Examples and Comparative Examples of the present invention.

Claims (8)

Sulfuric acid 0.5-2% by volume; 0.5 to 5% by volume phosphoric acid; 0.1 to 1% by volume of weak acid having an acid dissociation constant (pKa) of 3.0 or more; 0.01 to 0.1 volume percent hydrogen peroxide; And An etchant composition comprising the remainder of the pure water. The method of claim 1, Etching composition, characterized in that the weak acid is acetic acid. The method of claim 1, The etchant composition is characterized in that used in the dip type etching process. A seed layer forming step of depositing a metal on one surface of the substrate; A pattern forming step of coating a photoresist on the seed layer and forming a photoresist pattern through an exposure and development process; A filler forming step of forming a pillar by injecting a metal into an upper surface of the exposed seed layer not coated with the photoresist; A removal step of removing the photoresist except the filler; And A method for manufacturing a semiconductor device, comprising removing the seed layer on the bottom surface of the removed photoresist with the etchant composition according to any one of claims 1 to 3, except for the filler. 5. The method of claim 4, And a solder layer forming step of forming a solder layer on an upper surface of the filler after the filler forming step. 5. The method of claim 4, And the seed layer and the filler are formed of copper. The method of claim 5, And the solder layer is formed of lead, tin or an alloy thereof. 5. The method of claim 4, In the etching step, etching is performed for 30 seconds to 90 seconds.

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