TWI388678B - A method for manufacturing a high purity aluminum target for a liquid crystal display - Google Patents

Description

Method for manufacturing high-purity aluminum target for liquid crystal display

The present invention relates to a method for producing a target, and more particularly to a method for producing a high-purity aluminum target for a liquid crystal display.

5N (99.999%) or higher high-purity aluminum target is widely used in thin film transistor liquid crystal display (TFT-LCD) as electrode wire material because it has low resistivity and good thermal conductivity, that is, gate and source for transmitting scanning and signal. Extreme and bungee jumping. The application of aluminum target in liquid crystal display is mainly by DC magnetron sputtering. The argon ion ionized by the plasma is bombarded into the film material (ie, the sputtering target), so that the atom of the target is bombarded from the surface and deposited. A glass substrate is formed on the glass substrate to form a conductive film. In order to ensure that the film has a low electrical resistivity, it is necessary to form a film of a certain thickness. In general, the film thickness becomes thicker as the sputtering power and time increase. However, an increase in sputtering time reduces yield, increases production costs, and reduces product competitiveness. Therefore, if the sputtering rate of the target can be increased, the sputtering time can be reduced and the yield can be increased. Among them, the sputtering rate of the target is related to the microstructure and texture of the target in addition to the sputtering conditions.

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. The size of the 5N high-purity aluminum target for TFT-LCD is at least 980*890*16 mm (length*width) *Thickness), so cooling the aluminum blank to a low temperature of -50 °C requires a very large cooling bath and takes a long time. 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.

Japanese Patent No. Sho 63-312975 discloses that the manufacturing technique of a 5N aluminum target for an IC is subjected to recrystallization heat treatment after forging or rolling an aluminum blank, so that a (220)/(200) texture strength ratio <1.0 can be obtained. Sputter target. This patent does not disclose a detailed production technique, which should be cold rolled and then heat treated to produce a target, and thus is identical to the manufacturing technique of US Patent Publication No. 00103A1, both of which are applicable to small-sized targets. It is not suitable for large-size high-purity aluminum targets used in the TFT-LCD industry.

In addition, the aluminum target preparation technique disclosed in Japanese Patent Laid-Open No. 2007-63621 is that the aluminum ingot is subjected to hot rolling, and then subjected to a temperature rolling at 250 ° C, a cutting amount of 50%, or cold rolling, and then at 350 ° C for 2 hours. Annealing treatment, thus obtaining a completely recrystallized and fine-grained sputtering target. The technology disclosed in the patent includes three steps of hot rolling, cold rolling and recrystallization annealing, thereby greatly increasing the production cost and reducing the competitiveness of the product.

Therefore, it is necessary to provide an innovative and progressive manufacturing method for a high-purity aluminum target for a liquid crystal display to solve the above problems.

The invention provides a method for manufacturing a high-purity aluminum target for a liquid crystal display, comprising the steps of: (a) pre-heating an aluminum embryo having a purity greater than 99.999% (5N) at a temperature above 500 ° C; After hot rolling the preheating The aluminum embryo is hot rolled at a temperature of 200 ° C to 400 ° C to form an aluminum target substrate; and (c) a controlled cooling step is performed to cool the aluminum target substrate to form a high purity aluminum target.

The invention can be obtained by controlling the temperature and time of the pre-heat treatment, the rolling temperature, and a controlled cooling step (accelerated cooling) to obtain a microstructure with fine crystal grains and complete recrystallization in a specific direction. Sputter targets have excellent sputter properties. In addition, since the invention is directly produced by means of hot rolling, it is not necessary to adopt a heat treatment method after cold rolling, thereby greatly increasing the yield and saving equipment investment cost, thereby improving the competitiveness of the product.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart showing a method of manufacturing a high purity aluminum target for a liquid crystal display of the present invention. The manufacturing method of the present invention can be applied to various forms of liquid crystal displays (for example, a thin film sputtering process of the thin film transistor liquid crystal display (TFT-LCD) industry). First, referring to step S11, the aluminum embryo having a purity greater than 99.999% (5N) is preheated at a temperature above 500 ° C for a preheat treatment time. In the present embodiment, aluminum preform pre-heat treatment is performed at 500 ° C to 570 ° C in step S11, and preferably, the pre-heat treatment time is 2 to 8 hours. Wherein, the pre-heat treatment step can be carried out in an atmospheric furnace or an atmosphere furnace filled with hydrogen or argon.

Referring to step S12, the preheated aluminum blank is hot rolled and hot rolled at a temperature of 200 ° C to 400 ° C to form an aluminum target substrate. In this embodiment, in step S12, the preheated aluminum embryo is hot-rolled at a cutting amount of 30% to 65%, and the hot rolling is completed when the temperature of the aluminum blank is controlled to be 200 ° C to 400 ° C. . Wherein, the rolling temperature of the aluminum target substrate can be selected by thermocouple mode Or infrared measurement.

Referring to step S13, a controlled cooling step is performed to cool the aluminum target substrate to form a high purity aluminum target. In this embodiment, the controlled cooling mode in step S13 may be air cooling, air cooling or liquid cooling. Preferably, the air cooling method is fan cooling, and the air cooling method is preferably forced cooling by nitrogen or an inert gas (for example, argon (Ar)), and the liquid cooling method is preferably water cooling.

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

Example:

In the following examples, a 5N high-purity aluminum embryo of 160*200*100 mm (width x length x thickness) was subjected to hot rolling treatment after preheating at 530 ° C for 4 hours, in which each of the hot rolling was cut. The rate is 30%, the finishing temperature is 150-450 °C, after the hot rolling, the target is treated by water spray cooling and air cooling, and the prepared target is sputtered with a sputtering power of 500W. 2 shows a schematic diagram of the microstructure of the target obtained by the water-cooling and air-cooling treatment of the aluminum embryo of the present invention after pre-heat treatment and hot-rolling treatment at different finish rolling temperatures; FIG. 3 shows the target of the present invention. The texture analysis of the Orientation Distribution Function (ODF) of the material crystal structure; Table 1 shows the effect of the rolling temperature and the cooling mode after the rolling on the sputtering rate of the 5N aluminum target.

Example 1:

After the rolling temperature is 150 ° C, and the water-cooled target after the rolling is not completely recrystallized, the rolled band structure can be observed in a local area (as shown in the dotted circle of Figure 2 (a)); In addition, the Goss unrolled texture can also be observed from the texture analysis (as shown in Fig. 3(a)). This incompletely recrystallized target is affected by the thermal energy of the sputtering during the sputtering process, and the phenomenon that the unrecrystallized structure is sputtered on one side causes the sputtering operation to become unstable, resulting in a sputtering rate. Reduce (27.57 Å/s, refer to Table 1).

Example 2:

After the rolling temperature is 300 °C, and the water-cooled target after rolling, the grain structure is fine and uniform, showing a state of complete recrystallization (as shown in Fig. 2(b)), and a typical structure can be observed from the texture analysis. The {100}<001> cubic texture (as shown in Figure 3(b)), so the target has the highest sputtering rate (29.75Å/s, see Table 1).

Example 3:

The rolling temperature is the same as 300 ° C, but after the rolling, the natural cooling (air cooling) target, because the cooling rate is slow, the target is in a high temperature for a long time, forming a mixed crystal phenomenon of coarse crystal and fine crystal (such as Figure 2 (c)), and from the texture analysis can also be observed that it has only {110} <112> grains, but not the typical {100} <001> cubic texture (Figure 3 (c )))). Due to the purity of the 5N aluminum target Very high degree, no impurities or tiny precipitates can inhibit the growth of crystal grains. Therefore, if the target material is exposed to high temperature for a long time after rolling, it will inevitably cause the growth of crystal grains, resulting in a decrease in sputtering rate (27.53 Å/s, Refer to Table 1).

Example 4:

After the rolling temperature is 450 °C, although the water is cooled and cooled after the rolling, the grain is obviously roughened due to the too high rolling temperature (as shown in Fig. 2(d)), and {100}<001> is not formed. The cubic texture (as shown in Figure 3(d)), so the sputtering rate is greatly reduced (27.46 Å / s, refer to Table 1).

In summary, the present invention can obtain a microstructure which is fine and uniform in crystal grains and has complete recrystallization in a specific direction by controlling the temperature and time of the pre-heat treatment, the rolling temperature, and a controlled cooling step (accelerated cooling). Therefore, the sputter target produced has excellent sputtering properties, and the prepared grain size is below 300 μm, with {100}<001> recrystallized cubic texture, and the sputtering rate is higher than 29Å/s. . In addition, since the invention is directly produced by means of hot rolling, it is not necessary to adopt a method of heat treatment after cold rolling, so that the productivity is greatly improved, the equipment investment cost is saved, and the competitiveness of the product is improved.

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.

1 is a flow chart showing a method for manufacturing a high-purity aluminum target for a liquid crystal display according to the present invention; and FIG. 2 is a view showing that the aluminum embryo of the present invention is subjected to pre-heat treatment and hot-rolling treatment, respectively. Schematic diagram of the microstructure of the target prepared by water spray cooling and air cooling treatment at different finishing temperatures; and FIG. 3 shows a texture analysis diagram of the crystal structure direction distribution function of the target of the present invention.

(no component symbol description)

Claims (10)

A method for manufacturing a high-purity aluminum target for a liquid crystal display, comprising the steps of: (a) preheating an aluminum embryo having a purity greater than 99.999% (5N) at a temperature above 500 ° C; and (b) hot rolling The preheated aluminum embryo is hot rolled at a temperature of 200 ° C to 400 ° C to form an aluminum target substrate; and (c) a controlled cooling step is performed to cool the aluminum target substrate to form a high purity Aluminum target. The method of claim 1, wherein the aluminum embryo preheat treatment is performed at 500 ° C to 570 ° C in the step (a). The manufacturing method of claim 1, wherein the preheating time in the step (a) is 2 to 8 hours. The manufacturing method of claim 1, wherein the preheating treatment is carried out in an atmosphere furnace or an atmosphere furnace filled with hydrogen or argon in the step (a). The manufacturing method of claim 1, wherein in the step (b), the preheated aluminum embryo is hot-rolled at a cutting amount of 30% to 65% per pass. The manufacturing method of claim 1, wherein in step (b), the rolling temperature of the aluminum target substrate is measured by a thermocouple method or an infrared method. The manufacturing method of claim 1, wherein the controlled cooling mode in the step (c) is air cooling, air cooling or liquid cooling. The manufacturing method of claim 7, wherein the air cooling method is fan cooling, and the air cooling method is forced cooling by nitrogen gas or an inert gas, and the liquid cooling method is water cooling. The manufacturing method of claim 8, wherein the air cooling method is forced cooling with argon (Ar). The manufacturing method of claim 1, which is applied to a thin film sputtering process of the thin film transistor liquid crystal display (TFT-LCD) industry.