JP2001053024A - Al alloy electrode film and sputtering target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al alloy electrode film and a sputtering target used for forming the same which has an excellent dry-etching property. SOLUTION: This electrode film is composed of a composition in which 1-5 atom % of at least one or more elements elected from B, C, 4a group, 5a group, 6a group, Fe, Co, Ni, Ru, Rh, Pd and Pt are contained in total, 100 weight ppm or less of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba are contained and the rest is Al. The pattern thereof is formed by dry etching. This electrode film is obtained by a sputtering target corresponding to the above composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al alloy electrode film used for an electrode film of a semiconductor integrated circuit, a liquid crystal or the like, and a sputtering target used for forming the same.

[0002]

2. Description of the Related Art Among flat panel displays, TFT-LCD (Thin Film Trans) is particularly preferred.
istor Liquid Crystal Disp
lay), the width of the electrode film for driving the pixel is reduced with the increase in the definition of the pixel and the aperture ratio, and the specific resistance of a conventionally used film of Cr, Ta, Mo alloy, or the like is low. Because of high signal delay, Al-based electrode films having a lower specific resistance than these materials have recently been adopted.

Since the Al electrode film is inferior in heat resistance, there is a problem in a semiconductor integrated circuit that a disconnection occurs due to stress migration caused by film stress or electromigration caused by Joule heat caused by a drive current. Further, in the manufacturing process of the TFT, after the electrode film is formed, the CVD is performed.
(Chemical Vapor Deposition
When heating at 200 to 600 ° C. in the step of forming an insulating film according to n), there is a problem that a projection called a hillock is generated and the electrode is short-circuited. For this reason, improvement of heat resistance by alloying is being studied, and the following alloys are disclosed.

[0004] IBM J. M. Res. Developer. ,
461-463 (1970) shows that Cu is added to Al-Si alloy.
It is disclosed that the electromigration resistance is improved by the addition of. J. Vac. Sc
i. Technol. A8 (3), 1480-1483
(1990) discloses Al-S doped with rare earth element Sm.
It is disclosed that the m alloy film has heat resistance and hillock resistance. Vac. Sci. Technol. B9,
2542 (1991) discloses that an Al-Y alloy film to which a rare earth element Y is added has high hillock resistance. Japanese Patent Application Laid-Open No. 7-55555 discloses F
It is disclosed that an Al alloy film to which e, Co, Ni, Ru, Rh, Ir, and a rare earth element are added has excellent hillock resistance. In particular, recently, A to which Nd which is a rare earth element is added is used.
The l-Nd alloy film has been widely put into practical use as an electrode film of a TFT-LCD.

[0005]

At present, TFT-LCD
In the etching process, wet etching is the mainstream, but the cost of the chemical solution used is high, waste liquid treatment is complicated, and there is a concern about the effect on the environment,
The shift to dry etching which does not have these problems and is excellent in etching controllability is being studied. For dry etching of an Al-based film, Cl ₂ gas, BC
applying a high frequency electric field to generate a chloride cathode, between the anode with l ₃ gas, a method of etching by utilizing the volatility is the mainstream. However, in the case of the Al-rare earth element alloy film represented by the Al-Nd alloy, the chloride of the rare earth element is non-volatile and an etching residue is generated.
It is extremely difficult to apply dry etching. Also, A
The l-based film has a problem called after-corrosion in which the film is corroded after dry etching.

The above problem is a major problem that hinders dry etching in the patterning step of the Al-based electrode film. The present invention has been made in view of the above problems, and has as its object to provide an Al alloy electrode film having excellent dry etching properties and a sputtering target used for forming the same.

[0007]

The present inventor has conducted intensive studies to solve the above-mentioned problems, and as a result, has found that B, C, 4a and 5
a group, 6a group, Fe, Co, Ni, Ru, Rh, Pd,
Addition of elements selected from Pt and Li, Na, K, Rb,
The present inventors have found that an Al alloy electrode film having excellent dry etching properties can be obtained by reducing Cs, Be, Mg, Ca, Sr, and Ba, and reached the present invention. That is, the electrode film of the present invention is composed of B, C, 4a group, 5a group, 6a group, Fe, Co, Ni,
It contains at least one element of at least one element selected from Ru, Rh, Pd, and Pt in a total amount of 0.1 to 5 atomic%, and contains Li, Na, K, Rb, Cs, Be, Mg, Ca,
It is characterized in that the content of Sr and Ba is not more than 100 ppm by weight, and the balance is substantially made of Al, and the pattern is formed by dry etching.

Further, the sputtering target of the present invention comprises B, C, 4a, 5a, 6a, Fe, Co, N
i, Ru, Rh, Pd, Pt, at least one element selected from the group consisting of 0.1 to 5 atomic% in total.
Containing, Li, Na, K, Rb, Cs, Be, Mg, C
The total content of a, Sr, and Ba is 100 ppm by weight or less, and the balance is substantially composed of Al.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the important features of the Al alloy electrode film of the present invention is that B, C, 4a group, 5a group,
At least one element selected from the group consisting of Group 6a, Fe, Co, Ni, Ru, Rh, Pd, and Pt is used as a metal.
1 to 5 atomic%. B, C, 4a, 5a, 6a, Fe, C added to the electrode film of the present invention
Although o, Ni, Ru, Rh, Pd, and Pt are in a solid solution state in a matrix as they are formed by sputtering, part or all of them typically precipitate at grain boundaries in a heating step, and hillocks and migrations are prevented. It has an effect of improving heat resistance to prevent generation, and is characterized by being hardly left as it is removed as a volatile product during dry etching using a chlorine-based gas.

[0010] The reason that the content of the above-mentioned additional element is set to 0.1 to 5 atomic% is that the heat resistance is insufficient when the total addition amount is less than 0.1 atomic%, and when the total addition amount exceeds 5%, the ratio of the film increases. This is because the resistance increases. The selection of the additional elements and the setting of the total amount are preferably performed in consideration of the required heat resistance and specific resistance.
Incidentally, by selecting an appropriate element from the above-described additive element group, it is possible to impart corrosion resistance to an atmosphere to which the electrode film is exposed during the manufacture of the product or an atmosphere in which the product is used. For example, among the above-mentioned additional elements, Cr, Ta, T
Since i is an element forming a passive body, it has an effect of improving oxidation resistance. Since Ru, Rh, Pd, and Pt are electrochemically noble elements, they have an effect of increasing an electrode potential by being added. For example, in a structure in which ITO and an Al alloy electrode are laminated, an alkaline developer is used. This has the effect of preventing conduction failure due to oxidation and reduction reactions of the lamination interface that occurs when used.

In the present invention, Li, Na, K, Rb, C
The total content of elements selected from s, Be, Mg, Ca, Sr, and Ba is set to 100 ppm by weight or less, because if the content exceeds 100 ppm by weight, the occurrence of after-corrosion becomes remarkable. . The mechanism by which these elements cause after-corrosion is not clear, but because they are relatively stable chloride-generating elements, increasing their content increases the chlorides of these elements generated on the film surface, It is thought that it reacts with moisture and the like contained in the air when it is released to the atmosphere and corrodes the film. Li, N
Since a, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba cause a reduction in the conductivity of the electrode film, the content should be reduced as much as possible for the purpose of reducing the specific resistance. preferable. Li, Na, K, Rb, Cs, Be, M
g, Ca, Sr, Ba content is preferably 50 wt p
pm or less, more preferably 10 ppm by weight or less. In addition, elements that can be unavoidably mixed other than those described above do not affect the dry etching property, but affect the conductivity. Therefore, the total content is preferably 1,000 ppm by weight or less, more preferably 500 ppm or less.

The above-mentioned electrode film of the present invention comprises B, C, 4a
Group, 5a group, 6a group, Fe, Co, Ni, Ru, Rh,
The total content of Pd and Pt is in the range of 0.1 to 5 atomic%, and Li, Na, K, Rb, Cs, Be, Mg, Ca,
It can be formed by sputtering using the sputtering target of the present invention which has a total content of Sr and Ba of not more than 100 ppm by weight and a balance substantially consisting of Al.

The sputtering target of the present invention comprises:
An Al material obtained by applying a purification method such as a Zone Melting method, a three-layer electrolytic method, a Ziegler method, and an AlCl ₃ bath electrolytic refining method is used. Using a refined product, melt casting, powder metallurgy, spray forming, Liquid Dyn
It can be obtained by applying a technique such as amic Compaction. The dry etching method of the Al alloy film of the present invention is not particularly limited, but can be etched by a known technique such as plasma etching and reactive ion etching.

[0014]

EXAMPLE Purity 99.9 Purified by Three-Layer Electrolysis
A 9% Al raw material was weighed so as to have a desired composition, melted in vacuum, and machined into an ingot of φ100 × 4t to produce sputtering targets having the respective compositions shown in Table 1.
Further, as a comparative example, a sputtering target manufactured in the same manner as in the above-described present invention example was manufactured using a regenerated lump having a purity of 99% or more as an Al raw material.

[0015]

[Table 1]

These sputtering targets were mounted on a sputtering apparatus, and 25 × 50 × 1.1 mm, 100 × 1 using Ar gas by DC magnetron sputtering.
A 2000 mm thick thin film was formed on a # 7059 glass manufactured by Corning Co., Ltd. having a size of 00 x 1.1 mm. 25 × 50 × 1.
The sample having a size of 1 mm was heat-treated at 250, 350, and 450 ° C. for 30 minutes while evacuating to 10 ⁻¹ Pa or less, and then the specific resistance was measured by a direct current four-probe method. In addition, the surface of the sample subjected to heat treatment at 450 ° C. was evaluated by SEM observation as hillock resistance evaluation. The sample of 100 × 100 × 1.1mm size is made by Tokyo Ohka Kogyo Co., Ltd.
PR was coated at 2 μm, a strip pattern having a width of 20 μm was exposed, and developed using NMD-3, a developer of Tokyo Oka Kogyo Co., Ltd. to form a resist pattern. Next, these were subjected to BCl ₃ : Cl using a parallel plate dry etching apparatus.
₂ = 2: 1, pressure 10 mTorr, RF power 1500 W
After performing reactive ion etching under the conditions described above and removing the resist with a resist stripper, the surface state of the etched portion was observed by SEM.

(Surface Condition after Etching) As a result of SEM observation after dry etching, no residue on the etched surface of the Al alloy film of the present invention and no corrosion marks on the film surface due to after-corrosion were observed, and the dry etching property was excellent. It was judged. In addition, the main component content is the same as these, and Li, N
In the Al alloy film of the comparative example having a large content of a, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, a residue on the etched portion surface was not found, but a corrosion mark due to after-corrosion was seen. . The Al—Nd alloy film of the comparative example is N
A composition having a small d content did not show any etching residue, whereas a composition having a large Nd content showed etching residue and corrosion marks on the film surface due to after-corrosion.
It is assumed that this after-corrosion was caused by chlorine contained in the etching residue.

(Heat resistance) No hillocks were observed in the Al alloy film of the present invention. The Al—Nd alloy film of the comparative example is Nd
Hillock was not observed in the composition having a high content. Nd
Hillock was observed in the composition having a low content.

(Specific Resistance) Both the Al alloy film of the present invention and the Al alloy film of the comparative example tended to have a lower specific resistance as the heat treatment temperature was higher. Comparing the specific resistance of the film of the present invention and the film of the comparative example having the same main component content, Li, Na, K,
The specific resistance of the Al alloy film of the present invention having a small content of Rb, Cs, Be, Mg, Ca, Sr, and Ba is lower. Among the additional elements of the present invention, in particular, B and C have low specific resistances over the entire heat treatment temperature range, and then tend to have low Co and Ni. In the region where the heat treatment temperature is low, the group 4a element has a higher specific resistance than that of the element, but the heat treatment temperature is 450 ° C.
In this case, it decreased to a level next to the above-mentioned elements. Table showing the above results
See Figure 2.

[0020]

[Table 2]

Since the Al-Nd alloy film of the comparative example cannot reduce the etching residue while maintaining the heat resistance, it is not suitable for an electrode film requiring heat resistance and dry etching properties. On the other hand, it can be seen that the Al alloy electrode film of the present invention has excellent properties that achieve both heat resistance and dry etching properties.

[0022]

According to the present invention, an Al alloy film having both heat resistance and dry etching properties can be obtained, which is an indispensable technique for forming a high-definition Al alloy electrode film.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 KA16 KA18 MA05 MA14 MA15 MA16 MA18 MA19 NA18 NA25 NA27 NA28 4K029 AA09 BA23 BD02 CA05 DC04 DC08 4M104 BB02 BB39 DD40 DD65 GG20 HH14 HH20 5F004 AA08 BA04 BB29 DB11 DB11

Claims (2)

[Claims] 1. B, C, 4a, 5a, 6a, F
e, at least one element selected from the group consisting of elements selected from Co, Ni, Ru, Rh, Pd, and Pt.
Li, Na, K, Rb, Cs, B
An Al alloy electrode film, wherein the total content of elements selected from e, Mg, Ca, Sr, and Ba is 100 ppm by weight or less, and the balance is substantially Al, and the pattern is formed by dry etching. 2. B, C, 4a, 5a, 6a, F
e, at least one element selected from the group consisting of elements selected from Co, Ni, Ru, Rh, Pd, and Pt.
Li, Na, K, Rb, Cs, B
A sputtering target, wherein the total content of elements selected from e, Mg, Ca, Sr, and Ba is 100 ppm by weight or less, and the balance substantially consists of Al.