TWI398529B - Method for manufacturing aluminum target with high sputtering rate - Google Patents

Description

High sputtering rate aluminum target manufacturing method for LCD

The present invention relates to a method of manufacturing a target, and more particularly to a method of manufacturing an aluminum target for a high sputter rate LCD.

A high-purity aluminum target manufacturing technique disclosed in U.S. Patent Publication No. 00103A1, which is characterized in that an aluminum blank is cooled in a low temperature bath at -50 ° C, followed by forging or rolling, followed by recrystallization at 200 ° C or lower. By heat treatment, a sputtering target having a recrystallization ratio of 99%, a grain size of 200 μm or less, and a (200) texture strength of more than 35% can be obtained. Since the size of the 5N high-purity aluminum target for TFT-LCD is at least 980*890*16 mm (length*width*thickness), cooling the aluminum blank to a low temperature of -50 °C requires a very large cooling bath and is time consuming. Very long. In addition, the recrystallization heat treatment after cold rolling also requires a very large heat treatment furnace, and the above equipment investment will increase the production cost of the target. Therefore, the technology disclosed in this patent is only suitable for small targets, and is not suitable for TFT-LCD. Manufacture of large-size, high-purity aluminum targets.

In addition, Japanese Patent Laid-Open No. 2007-63621 discloses that an aluminum ingot is subjected to hot rolling at a cutting temperature of 50% at 250 ° C, and then annealed at 350 ° C for 2 hours to obtain a completely recrystallized sputtering target. However, after the hot rolling is completed, the aluminum ingot obtained by the method is cooled to a normal temperature by air cooling. Since the high-purity aluminum target has few impurity atoms, a slight temperature causes grain growth, so the method disclosed in the Japanese patent cannot Avoid grain growth of the aluminum target during air cooling. In addition, since the microstructure of the aluminum target is closely related to the sputtering rate, the aluminum target produced by the method of the Japanese patent has a coarse grain size, and the sputtering rate is low, resulting in a thin aluminum film after sputtering. There is a problem that the resistance value is high.

Therefore, it is necessary to provide an innovative and progressive method for manufacturing an aluminum target for a high sputter rate LCD to solve the above problems.

The invention provides a method for manufacturing an aluminum target for a high sputter rate LCD, comprising the steps of: (a) heating an aluminum ingot to a first temperature and holding the temperature for a set time; (b) rough rolling the aluminum ingot to a first a thickness; (c) an aluminum ingot after the first water-cooling rough rolling to a second temperature; (d) an aluminum ingot after the first water-cooling after finishing rolling to a second thickness; (e) a second water-cooled finishing rolling The aluminum ingot is then brought to room temperature; and (f) the aluminum ingot after the second water cooling is heat treated to form an aluminum target.

The aluminum target produced by the manufacturing method of the present invention can refine the crystal grains of the aluminum target by the first water cooling and the second water cooling, and promote the recrystallization of the aluminum target by heat treatment, and eliminate the residual of the aluminum target after the hot rolling. The strain can therefore make the aluminum target have a higher sputtering rate, and can effectively avoid the problem that the film resistance is high due to insufficient thickness of the film after sputtering. Moreover, the manufacturing method of the present invention can shorten the time of cooling and cooling after hot rolling, and increase the yield of the aluminum target.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing the manufacturing method of the aluminum target for high sputter rate LCD of the present invention. The manufacturing method of the present invention can be applied to various forms of liquid crystal displays, such as a thin film sputtering process of the thin film transistor liquid crystal display (TFT-LCD) industry. First, referring to step S11, an aluminum ingot is heated to a first temperature and held for a set time. The purity of the aluminum ingot is higher than 99.99%. The step of heating the aluminum ingot can be carried out under the atmosphere or under a protective atmosphere. Preferably, in step S11, the first temperature system is 250 to 550 ° C, and the set time is 1 to 3 hours.

Referring to step S12, the aluminum ingot is roughly rolled to a first thickness. In the present embodiment, the cutting amount per pass of the rough rolling aluminum ingot is preferably 5 to 20%, and the temperature of the aluminum ingot after the rough rolling is preferably 300 to 550 °C.

Referring to step S13, the aluminum ingot after the first water-cooling rough rolling is brought to a second temperature. In this embodiment, the water temperature of the first water cooling is preferably 5 to 35 ° C, and the second temperature is 260 to 320 ° C.

Referring to step S14, the aluminum ingot after the first water cooling is finish rolled to a second thickness. In the present embodiment, the amount of cut per pass of the ingot is preferably 30 to 60%, and the temperature of the aluminum ingot after completion of the finish rolling is preferably 210 to 260 °C.

Referring to step S15, the aluminum ingot after the second water-cooled finish rolling to room temperature. In this embodiment, the water temperature of the second water cooling is preferably 5 to 35 °C.

Referring to step S16, the aluminum ingot after the second water cooling is heat treated to form an aluminum target. In the present embodiment, the heating temperature in the heat treatment step is preferably from 100 to 350 ° C, and the heating time is from 0.5 to 3 hours. In step S16, the heat treatment step is carried out under atmospheric or protective atmosphere.

In this embodiment, after step S16, a step S17 of cooling the aluminum target to room temperature is further included. In step S17, the cooling mode may be air cooling, forced air cooling, water cooling or liquid nitrogen cooling. Wherein, if the cooling method is water cooling, the water temperature is preferably 5 to 40 ° C; if the cooling method is forced air cooling, the cooling gas may be selected from nitrogen, argon or atmosphere.

The invention is illustrated by the following examples, which are not intended to be limited to the scope of the invention.

Example:

In the present example, an aluminum target is produced by using an aluminum ingot of high purity 5N (99.999%) or more as an example. First, in the heating step, an aluminum ingot having a purity higher than 99.999% is heated to 500 ° C (first temperature) in an oven and held at a temperature of 2 hours (set time). (Step S11)

Next, a rough rolling step is performed, and the heated high-purity aluminum ingot is subjected to rough rolling, and the thickness of the aluminum ingot is roughly rolled from 100 mm to 50 mm (first thickness) at a cutting amount of 10 mm per pass. The temperature of the aluminum ingot is about 460 °C. (Step S12)

Next, a process water cooling step (first water cooling step) is performed to cool the aluminum ingot spray water after the rough rolling, and the temperature of the aluminum ingot is rapidly lowered from 460 ° C to 280 ° C (second temperature). (Step S13)

Then, the finishing rolling step is further performed, and the aluminum ingot after the process water cooling is finished by two passes to 18 mm (second thickness). (Step S14)

Next, the rolling water cooling step (second water cooling step) is performed, and the aluminum ingot which has been subjected to the finish rolling is sprayed and cooled, and the aluminum ingot is rapidly cooled to room temperature. (Step S15)

Next, a heat treatment step is performed to cut the high-purity aluminum ingot which has been subjected to water-cooling (cutting is an optional step depending on the size of the desired aluminum target), and then placed in a furnace at 200 The temperature was held at ° C for 1 hour to form an aluminum target. (Step S16)

Finally, after the heat treatment is completed, the aluminum target is taken out and cooled in the air. (Step S17)

Figure 2(a)-2(d) shows that after hot rolling under the same hot rolling parameters, air cooling (air cooling), water cooling only, double water cooling (process water cooling + finish rolling water cooling) and double Water cooling + heat treatment (ie, the method of the present invention), the crystal phase microstructure of the obtained aluminum target; FIG. 3 (a) - 3 (d) shows that after hot rolling under the same hot rolling parameters, respectively A texture analysis diagram of the crystal structure direction distribution function of the aluminum target obtained by air cooling, only water cooling, double water cooling, and double water cooling + heat treatment.

Referring to FIG. 2 and FIG. 3, the aluminum target obtained by the process of the above example has a grain size of about 150 μm (as shown in FIG. 2(d)) and has {100}<001> cubic weave. Structure (as shown in Figure 3 (d)).

It can be clearly seen from Fig. 2(a)-2(d) that whether it is only applied to the cold-cooled aluminum target (refer to Fig. 2(b)), the double water-cooled aluminum target (refer to Fig. 2(c)) or The double-water-cooled + heat-treated aluminum target (refer to Figure 2(d)) has a microstructure that is more detailed than an air-cooled aluminum target (see Figure 2(a)).

It should be emphasized that the aluminum targets in Fig. 3(a)-3(c) which are air-cooled, only water-cooled and double-water-cooled but not heat-treated have no {100}<001> cubic texture; The aluminum target shown in Fig. 2(c) and Fig. 3(c), the double-water-cooled and heat-treated aluminum target shown in Fig. 2(d) and Fig. 3(d), the grain structure is only slightly enlarged, however The grain size distribution is more uniform and there is a significant {100}<001> cubic texture (refer to Figure 3(d)), which can increase the sputtering rate of the aluminum target.

Referring to Figure 4, there is shown the actual measurement of the sputtering rate of the aluminum target produced by the above four different conditions. The results in Figure 4 show that the air-cooled aluminum target has a sputtering rate of 27.53. /sec; After rolling water or double water cooling, the sputtering rate of the aluminum target is increased to 29.75 /sec and 30.33 /sec. The double-water-cooled and heat-treated aluminum target increases the sputtering rate to 32.05 /sec, the sputtering rate of the air cooled aluminum target 27.53 /sec, an increase of 16.41%.

The aluminum target produced by the manufacturing method of the invention can refine the crystal grains of the aluminum target by double water cooling (first water cooling + second water cooling), promote recrystallization of the aluminum target by heat treatment, and eliminate residual aluminum after hot rolling The strain inside the target can therefore make the aluminum target have a higher sputtering rate, and can effectively avoid the problem that the film resistance is high due to insufficient thickness of the film after sputtering. Moreover, the manufacturing method of the present invention can shorten the time of cooling and cooling after hot rolling, and increase the yield of the aluminum target.

The above embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The scope of the invention should be as set forth in the appended claims.

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1 is a flow chart showing a method of manufacturing an aluminum target for a high sputter rate LCD of the present invention;

2(a)-2(d) show the aluminum target produced by hot rolling after air rolling, air cooling only, double water cooling and double water cooling + heat treatment under the same hot rolling parameters. Crystal phase microstructure;

3(a)-3(d) show the aluminum target produced by hot rolling after air rolling, air cooling only, double water cooling and double water cooling + heat treatment under the same hot rolling parameters. Texture analysis of the crystal structure direction distribution function; and

Figure 4 shows the actual measurement results of the sputtering rate of the prepared aluminum target by air cooling, only water cooling, double water cooling, and double water cooling + heat treatment, respectively.

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Claims (16)

A method for manufacturing an aluminum target for a high sputter rate LCD, comprising the steps of: (a) heating an aluminum ingot to a first temperature and holding the temperature for a set time; (b) rough rolling the aluminum ingot to a first thickness; (c) the aluminum ingot after the first water-cooled rough rolling to a second temperature; (d) the aluminum ingot after the first water-cooling finish to a second thickness; (e) the aluminum after the second water-cooled finish rolling The ingot is brought to room temperature; and (f) the aluminum ingot after the second water cooling is heat treated to form an aluminum target. The manufacturing method of claim 1, wherein in the step (a), the purity of the aluminum ingot is higher than 99.99%. The manufacturing method of claim 1, wherein in the step (a), the first temperature system is 250 to 550 ° C, and the set time is 1 to 3 hours. The production method of claim 1, wherein the aluminum ingot is heated in the atmosphere (a) under a protective atmosphere in the step (a). The manufacturing method of claim 1, wherein in the step (b), the amount of cutting per pass of the rough-rolled aluminum ingot is 5 to 20%. The manufacturing method of claim 1, wherein in the step (b), the temperature of the aluminum ingot after the rough rolling is 300 to 550 °C. The manufacturing method of claim 1, wherein in the step (c), the water temperature of the first water cooling is 5 to 35 ° C, and the second temperature is 260 to 320 ° C. The manufacturing method of claim 1, wherein in the step (d), the amount of cut per pass of the aluminum ingot is 30 to 60%. The manufacturing method of claim 8, wherein the temperature of the aluminum ingot after completion of the finish rolling is 210 to 260 °C. The manufacturing method of claim 1, wherein in the step (e), the water temperature of the second water-cooling is 5 to 35 °C. The manufacturing method of claim 1, wherein in the step (f), the heating temperature in the heat treatment step is 100 to 350 °C. The manufacturing method of claim 11, wherein the heating time in the heat treatment step is 0.5 to 3 hours. The manufacturing method of claim 1, wherein the heat treatment step is carried out under the atmosphere or a protective atmosphere in the step (f). The manufacturing method of claim 1, wherein after the step (f), the step of cooling the aluminum target to room temperature is further performed by air cooling, forced air cooling, water cooling or liquid nitrogen cooling. The method of claim 14, wherein the water-cooled water temperature is 5 to 40 °C. The manufacturing method of claim 14, wherein the forced air cooling gas system is nitrogen gas, argon gas or atmosphere.