KR20020097348A - Etching solution for copper titanium layer and etching method thereof - Google Patents

Abstract

PURPOSE: An etching solution for copper titanium layer is provided, which has excellent taper profile against copper layer while etching copper layer and titanium layer at the same time, and has decreased attack against glass substrate and lower silicon layer, thus it is applicable to TFT LCD manufacture process. CONSTITUTION: The etching solution comprises 0.1 to 5 wt.% of inorganic oxidizers selected from the group consisting of CuCl2, Cu(NO3)2, CuSO4, Al(NO3)3, Al2(SO4)3, FeCl3, Fe2(SO4)3 and Fe(Cl4)3; 0.5 to 10 wt.% of inorganic acid or their salts; 0.05 to 0.5 wt.% of fluorine; and a balance of deionized water, and optionally 0.005 wt.% or more of additives selected from the group consisting of pyrrolidine, pyrrolin, pyrrol, indole, pyrazol, imidazol, pyrimidine, purine, pyrimidine and their derivatives.

Description

Etching solution of copper titanium film and its etching method {ETCHING SOLUTION FOR COPPER TITANIUM LAYER AND ETCHING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching solution used for wet etching a metal film in a semiconductor device and an etching method thereof, and more particularly to an etching solution for etching a copper titanium metal film in a semiconductor device and an etching method thereof.

The process of forming the metal wiring on the substrate in the semiconductor device is generally composed of a metal film forming process by sputtering or the like, a photoresist forming process in a selective region by photoresist coating, exposure and development, and an etching process. And washing processes before and after individual unit processes. The etching process refers to a process of leaving a metal film in a selective region using a photoresist as a mask, and typically, dry etching using plasma or wet etching using an etching solution is used.

In such semiconductor devices, the resistance of metallization has recently emerged as a major concern. Since resistance is a major factor in causing RC signal delay, especially for TFT LCD (thin film transistor liquid crystal display), it is important to increase panel size and high resolution.

Therefore, in order to realize the reduction of RC signal delay, which is essential for the large-sized TFT LCD, low-resistance material development is essential and chromium (Cr resistivity: 12.7 × 10 ^-8 Ωm) and molybdenum (Mo Resistivity: 5 x 10 ^-8 mm, aluminum (Al resistivity: 2.65 x 10 ^-8 mm) and alloys thereof are difficult to use for gate and data wiring used in large-sized TFT LCDs.

Under such a background, there is a high interest in a copper film, which is one of the new low resistance metal films. This is because the copper film is known to have an advantage that the resistance is significantly lower than that of the aluminum film or the chromium film, and there is no big problem in the environment. However, many difficulties have been found in the process of coating and patterning a photoresist of copper, and a problem of deterioration in adhesion with a silicon insulating film has been found.

On the other hand, the research on the multi-metal film to compensate for the shortcomings of the low-resistance copper single layer is in progress, and among them, the material which is in the spotlight is a copper titanium film. There is an etching solution known in the art for this copper titanium double layer.

According to Korean Patent Publication No. 2001-11390, a gate electrode is formed by sequentially depositing a copper film and a titanium film on a substrate, and simultaneously etching the copper film as the first gate metal and the titanium film as the second gate metal according to a predetermined pattern. Disclosed is a method of forming a gate electrode of a thin film transistor comprising the step of forming the same, and the etchant used in the etching process is a mixture of HF and HNO ₃ + CH ₃ COOH.

However, in the case of the etching solution in which the etching solution of the known copper film and the etching solution of the titanium film are mixed, the tape profile is poor, and there are many difficulties in the subsequent process, and in particular, the fluorine used for etching the titanium film ( F) Since ions attack the glass substrate and the silicon layer, they are not actually suitable for use in the process.

Therefore, in order to solve the above-mentioned problems, the tape profile for the copper film is good while simultaneously etching the copper and titanium films and the attack on the glass substrate and the silicon layer under the surface is minimized, thereby being applied to an LCD manufacturing process. Provide an etching solution without any difficulty and its etching method.

In addition, as in the case of chromium and the like, by using a substance specified as an environmentally harmful substance by using copper, it provides a low-resistance metal wiring and an etching solution and an etching method for manufacturing an environmentally friendly semiconductor device.

1A to 1F illustrate an etching process according to an embodiment of the present invention.

2 is a view showing an example of an etching profile of a copper titanium double layer which is an embodiment according to the present invention.

3 is a view showing an example of an etching profile of a copper film according to the prior art.

4 is a view showing an etching rate with respect to the weight% of each composition in the etching of copper titanium double layer which is an embodiment according to the present invention.

※ Description of the main parts of the drawings

10 glass substrate 12 titanium film

14 copper film 16 photoresist

As a means for realizing the object of the present invention, there is provided an etching solution of a copper titanium film containing an inorganic salt oxidant, an inorganic acid or a salt thereof, a fluorine-source, and deionized water. More specifically, a copper titanium film comprising 0.1 to 5% by weight of an inorganic salt oxidizing agent, 0.5 to 10% by weight of an inorganic acid or salt thereof, 0.05 to 0.5% by weight of a fluorine-source, and deionized water. Provide an etching solution. In addition, if necessary, the etching solution of the copper titanium film further comprises an additive of 0.005% by weight or more in the above-described etching solution.

The limitation of such a composition ratio is better understood through the following examples. For example, the above-described etching solution may include 0.5 wt% of inorganic salt oxidizing agent, 1 wt% of inorganic acid or salt thereof, and 0.2 wt% of fluorine-. Source, and 0.02% by weight of additive, the balance being diluted with deionized water.

Copper titanium film includes a double film of "titanium / copper film" having a copper film as a bottom film and a titanium film as a top film, and a "copper / titanium film" having a titanium film as a bottom film and a copper film as a top film. For example, it also includes the case of the multiple metal film more than the triple metal film which alternately laminates a titanium film, a copper film, and a titanium film. Accordingly, the copper titanium film means a plurality of multiple films in which a copper film and a titanium film are alternately arranged. The copper titanium film may determine the structure of the multilayer by considering a material or adhesion of the film disposed below the copper titanium film or the film disposed above. In addition, the copper film and the titanium film are not limited in thickness to each other, and various combinations are possible. For example, the thickness of the copper film may be greater than the thickness of the titanium film, or may be formed small, and more particularly, may include a case formed only of the copper film.

Inorganic salt oxidizing agents, inorganic acids or salts thereof, fluorine sources and additives can be prepared by conventionally known methods, and preferably have a purity for semiconductor processing, deionized water is preferably used for semiconductor processing. Use water of MΩ / cm or more. In addition, other additives usually used may be used for the etching solution.

The inorganic salt oxidizing agent, and the inorganic acid or its salt are the main components to etch the copper film, and the inorganic salt oxidizing agent refers to an oxidizing agent containing an inorganic salt, and various kinds are possible, and preferably CuCl ₂ , Cu (NO ₃ ) ₂ , CuSO ₄ , Al (NO ₃ ) ₃ , Al ₂ (SO ₄ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Fe (Cl ₄ ) _3, and the like. Various kinds are possible without particular limitation, and preferably include AcOH, H ₂ SO ₄ , HNO ₃ , H ₃ PO ₄ , HClO ₄ , or salts derived from the respective acids.

Fluorine-source refers to all compounds containing fluorine ions as a main component for etching titanium, and is not particularly limited and can be various kinds, preferably HF, KF, NaF, H ₂ SiF ₆ , NH ₄ F.HF or a mixture of two or more thereof can be used.

Preferably, additives may be added to the above-mentioned composition as needed. This additive is not a component for determining whether to etch, but serves to improve the tape profile of the copper film and to reduce the attack on the glass substrate or the semiconductor layer. In some cases, when such an additive is not added, a pattern of cdromide of 1 μm or more or a silicon layer may be etched, a tape profile may be poor, and a tape angle of 60 degrees or more may occur. Can cause serious problems in subsequent processes. The additive is not particularly limited and various types are possible, and preferably pyrrolidine, pyrroline, pyrrole, indole, pyrazole, imidazole, Pyrimidine, Purine, Pyridine and the like and derivatives thereof may be used.

Another means for realizing the object of the present invention is to use a first step of depositing a copper titanium film on the substrate, a second step of selectively leaving a photoresist on the copper titanium film, and using an etching solution of the above-described composition range It provides an etching method of a copper titanium film comprising a third step of etching the copper titanium film.

Preferably, a semiconductor structure is formed between the substrate and the copper film or between the substrate and the titanium film. Such semiconductor structures include semiconductor structures for display devices such as LCDs and PDPs, such as dielectric films by chemical vapor deposition, conductive materials by sputtering, and silicon films such as amorphous or polycrystalline silicon films. It means a structure manufactured by a photo process, an etching process, etc. including one or more films.

Preferably, the above-described copper titanium film can form source / drain wirings constituting a data line of the TFT-LCD. Since the source / drain wiring of the TFT-LCD is a wiring whose resistance is a problem in particular, it is possible to use a copper titanium film and easily etch it with the etching solution according to the present invention, thereby enabling the enlargement of the TFT LCD.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

However, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the film thickness and the like in the drawings are exaggerated to emphasize the clear explanation. Also, if a film is described as "on" another film or substrate, the film may be present in direct contact with the other film or substrate, or a third film may be interposed therebetween.

(Example 1)

1A to 1F, an embodiment of an etching process according to the present invention will be described. The substrate 10 described above continuously deposits the titanium film 12 and the copper film 14 on a glass substrate by chemical vapor deposition known to those skilled in the art, and the thickness of the titanium film 14 is approximately 200 GPa and the copper film is Approximately 1500 mW (FIG. 1A). A display device structure (not shown) may be added between the glass substrate 10 and the titanium film 12. The structure for a display device is formed by forming a pattern on various oxide films such as silicon oxide film and silicon nitride film, or semiconductor films such as amorphous silicon and polysilicon, or conductive layers such as doped amorphous doped polysilicon and various metal films. It means a structure formed by overlapping at least two. In addition, on the substrate 10, the copper film, the titanium film, and the like, a conventional cleaning process as known to those skilled in the art is performed.

Next, in order to form a copper titanium double layer at an optional site, a photoresist is applied (FIG. 1B), selectively exposed using a mask and partially removed by the developer (FIG. 1C). In this case, the photoresist may be a cathode or an anode reactant, and in the case of the anode photoresist, the exposed portion is developed, and the cathode photoresist is developed in that the unexposed portion is developed. In addition, a process such as ashing, heat treatment, and the like, which are commonly performed, may be added to the process.

Thereafter, a copper titanium double layer etching process is performed using an etching solution composed of 0.5 wt% of an inorganic salt oxidizing agent, 1 wt% of an inorganic acid, 0.2 wt% of a fluorine-source, 0.01 wt% of an additive, and 98.29 wt% of deionized water. . 1D shows a situation in which the copper film is first etched. Subsequently, the titanium film is etched by the same etching solution (FIG. 1E). Fig. 1E is a diagram showing an exaggerated actual film thickness and the like. The etching process of such a copper titanium double layer may be carried out according to a method well known in the art, it may be exemplified immersion, spray, etc., and preferably using an immersion method. During the etching process, the temperature of the etching solution is around 30 ℃, and the proper temperature can be changed as necessary due to other process conditions and other factors. The etching time may vary depending on the etching temperature, but usually proceeds about 50 to 150 seconds. Finally, the photoresist is removed from the front to form the shape shown in FIG. 1F. In the drawings, it is shown with a predetermined tape angle for ease of understanding.

The profile of the copper titanium bilayer etched by this process was examined using a cross-sectional SEM (Model S-4200, manufactured by Hitachi). The measured etch rate is about 16.4 dl / sec, and FIG. 2 shows the etch profile of the copper titanium bilayer described above. Here, the excellent tape profile and etching rate of the copper titanium double layer are shown.

For comparison, an etching photograph of a conventional copper single layer is shown in FIG. 3. In the case of the comparative example consisting of only a copper film, it is difficult to directly compare it with the case of Example 1, which is actually made of a copper titanium double layer structure, but in Example 1, the lower film is about 200 Å and the upper film is a copper film. Since it is about 1500 mW, an indirect comparison can be made. As shown in FIG. 2, it can be seen that the etching profile of Example 1 shows a remarkably excellent characteristic when compared except for a portion where a titanium film, which is a relatively thin lower layer, is formed.

On the other hand, as a result, it can be seen that even when the above-described etching solution is applied to the copper single layer, a predetermined effect can be assisted.

(Examples 2 to 13)

In a similar manner as in Example 1, only the composition ratio of the etching solution was changed to perform the cleaning process in the same manner. Detailed process progress is not described again for the sake of brevity. Table 1 shows the composition ratio of Examples 2 to 13 and the etching rate accordingly.

Example Composition (% by weight) Etching Speed (Å / sec) Inorganic salt oxidizer Inorganic acids or salts thereof Fluorine-Source additive 2 0.1 0.5 0.05 0.005 9.1 3 0.2 0.5 0.1 0.005 11.2 4 0.5 0.5 0.1 0.005 13.6 5 One 2 0.2 0.02 23.4 6 One 3 0.2 0.05 25.5 7 One 3 0.4 0.01 30.3 8 2 2 0.2 0.1 28.6 9 3 5 0.4 0.01 28.7 10 3 10 0.2 0.1 30.0 11 4 5 0.4 0.2 30.1 12 4 10 0.2 0.2 34.5 13 5 2 0.2 0.5 33.3

As shown in Table 1, it can be seen that the etching rate is determined according to the amount of the inorganic salt oxidizing agent and the inorganic acid or salt thereof. The correlation between the weight percent of each composition and the etching rate is shown in FIG. 4.

Hereinafter, the characteristics of the copper titanium double film etching solution prepared outside the preferred composition ranges of Examples 1 to 13 will be described.

First, when the inorganic salt oxidant is 5 wt% or more, the CD profile is large, and the tape profile is deteriorated due to the difference in etching rates between the titanium film and the copper film. Process advantages are eliminated, and there is a risk of damaging the glass substrate by etching for a long time. Therefore, the composition range of the inorganic salt oxidizing agent is preferably 0.1 to 5% by weight.

Secondly, the inorganic acid or its salt, together with the inorganic salt oxidizing agent, is a component that facilitates etching of the copper film, and when it is 10% by weight or more, the CDOS of the copper film is large and the tape profile is deteriorated. The damage to the substrate is very severe and can not be used in the process. In addition, when less than 0.5% by weight, the copper film is hardly etched, or even if etched, the etching rate is significantly low, there is no advantage to apply in the process. Therefore, the composition range of the inorganic acid or its salt is preferably 0.5 to 10% by weight.

Third, the fluorine-source is a main component for etching the titanium film and may damage the glass substrate. Therefore, when the amount is high, the glass substrate is severely damaged, and thus, the implementation of a stable process is not easy. When the fluorine-source is more than 0.5% by weight, the glass substrate is etched like a wave pattern after etching, and when the fluorine-source is less than 0.05% by weight, the etching rate of the titanium film is too low, so there is no advantage in process application. On the other hand, since the etching time becomes long, damage to the glass substrate cannot be avoided. Therefore, the composition range of the fluorine-source is preferably 0.05 to 0.5% by weight.

Fourth, the additive added to the etching solution as needed is an important component to reduce the damage of the glass substrate caused by the fluorine-source, and to improve the tape profile of the copper film. It can be expected to increase. However, the content of the additive was judged to have saturation with a certain threshold, which was determined to be approximately 0.5% by weight. On the other hand, when the additive is less than 0.005% by weight, damage to the glass substrate may be reduced, and the role of improving the tape profile may not be sufficiently performed. Therefore, the composition range of the additive which can be administered as needed is preferably 0.005% by weight or more, and more preferably 0.005% by weight or more and 0.5% by weight.

In another embodiment of the present invention, the display device structure of the above-described embodiments 1 to 13 is a structure including a TFT LCD gate wiring, an insulating film, a semiconductor layer, and the like, and the copper titanium film is a source / drain wiring.

After forming a buffer layer made of a transparent insulating material on the glass substrate or performing a cleaning process without forming such a buffer layer, a first conductive layer corresponding to the gate electrode and the wiring is formed, and then the gate insulating film, Therefore, the insulating film which forms a storage capacitor is formed.

A semiconductor layer, such as amorphous silicon (a-Si) or polysilicon (poly-si), which becomes an active region on the insulating film is formed to pattern a predetermined region to form a channel region of the transistor element. There are a source / drain electrode ohmicly connected to the semiconductor layer forming the channel region, and a second conductive layer forming the data wiring. Then, an insulating layer is usually formed on the second conductive layer.

In such a structure, a copper titanium double film is usually used as the second conductive layer which requires a lower resistance. In addition, the above-described etching solution and the etching method may be applied to pattern the copper titanium multilayer. However, the present invention is not necessarily limited thereto, and it is obvious that the present invention can be used for the above-described first conductive layer (gate wiring).

In addition, in the present embodiment, only the copper titanium double layer is mainly mentioned, but in the case of triple layer or more consisting of copper and titanium, the etching process may be performed with the above-described etching solution, and the copper or titanium film may be formed by chemical vapor deposition. It is customizable in the art.

In particular, even in the case of a copper film without a titanium film among the copper titanium film, a predetermined effect can be obtained by such an etching solution and an etching method.

While specific embodiments of the invention have been described and illustrated above, it will be apparent that the invention may be embodied in various modifications by those skilled in the art.

Accordingly, various modifications, equivalents, and the like may be made without departing from the spirit or scope of the claims of the present invention, and thus, such things should be regarded as within the claims of the present invention.

As described above, using the etching solution and the etching method according to the present invention has a good tape profile, it is possible to minimize the attack on the glass substrate and the lower semiconductor layer to stabilize the subsequent process. In addition, the low-resistance metal wiring and the environmentally friendly semiconductor device can be produced.

Claims (13)

0.1 to 5% by weight of inorganic salt oxidizer relative to the total weight of the composition; 0.5 to 10% by weight of an inorganic acid or salt thereof based on the total weight of the composition; 0.05 to 0.5 weight percent fluorine-source relative to the total weight of the composition; And Etching solution of a copper titanium film comprising deionized water to the total weight of the total composition is 100% by weight. The etching solution of claim 1, further comprising at least 0.005% by weight of an additive based on the total weight of the total composition. The method of claim 2, wherein the additive is selected from the group consisting of pyrrolidine, pyrroline, pyrrole, indole, pyrazole, imidazole, pyrimidine, purine, pyridine and derivatives thereof. solution. The copper titanium film etching solution according to claim 1 or 2, wherein the copper titanium film is a double film in which a copper film is formed on the titanium film. The copper titanium film etching solution of claim 4, wherein the copper film has a thickness greater than that of the titanium film. The method according to claim 1 or 2, wherein the inorganic salt oxidizing agent is CuCl ₂ , Cu (NO ₃ ) ₂ , CuSO ₄ , Al (NO ₃ ) ₃ , Al ₂ (SO ₄ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , Fe (Cl ₄ ) _{3 The} etching solution of the copper titanium film, characterized in that selected from the group consisting of. Depositing a copper titanium film on the substrate; A second step of selectively leaving photoresist on the copper titanium film; And The etching method of the copper titanium film, characterized in that it comprises a third step of etching the copper titanium film using an etching solution according to claim 1. 8. The method of claim 7, wherein the copper titanium film is a double film in which a copper film is formed on the titanium film. The method of claim 8, wherein the copper film has a thickness greater than that of the titanium film. 8. The etching method according to claim 7, wherein the additive is selected from the group consisting of pyrrolidine, pyrroline, pyrrole, indole, pyrazole, imidazole, pyrimidine, purine, pyridine and derivatives thereof. Way. The method of claim 7, wherein the inorganic salt oxidizing agent is CuCl ₂ , Cu (NO ₃ ) ₂ , CuSO ₄ , Al (NO ₃ ) ₃ , Al ₂ (SO ₄ ) ₃ , FeCl ₃ , Fe ₂ (SO ₄ ) ₃ , An etching method of copper titanium film, which is selected from the group consisting of Fe (Cl ₄ ) ₃ . 8. The method of claim 7, wherein the substrate is a glass substrate for a TFT LCD. 8. The method of claim 7, wherein the copper film is source / drain wiring.