A preparation method of an ITO planar target

Abstract

The present invention discloses a preparation method of an ITO planar target, belonging to the technical field of target preparation. By setting a special sliding structure and a heat insulation structure on the supporting plate of the sintering furnace during the sintering process of the target blank, this method can effectively suppress the warping problem of the generated ITO planar target without changing the heating method, and at the same time, no cracking phenomenon will occur.

Description

Technical Field

[0001] The present invention relates to the field of target preparation, and particularly to a silicon-aluminum target and a preparation method thereof. Background Art

[0002] During the sintering preparation process of ITO planar targets, obvious shrinkage phenomena will occur. To overcome the influence brought by this phenomenon, in the prior art, gaskets are laid on the supporting plates of the sintering furnace when sintering target blanks, then some high-temperature-resistant metal powders are placed on the gaskets, and finally the target blanks are placed for sintering. This method can effectively suppress the problem of unsmooth exhaust at the bottom of the target blank at high temperatures, thereby reducing the warping phenomenon of the target. However, due to the relatively large friction coefficient of the supporting plate itself, and the shrinkage degree of the target blank itself has not been reduced, the design of the gasket may instead cause the shrinkage of the target to be blocked, eventually cracking or even breaking; on the other hand, since the sintering furnace generally uses heating wires around the furnace to supply heat to the target blank in the center, a gradient temperature zone will inevitably be formed in the furnace during sintering, so it is very difficult to effectively solve the warping problem of the prepared ITO planar target. Summary of the Invention

[0003] Based on the defects existing in the prior art, the purpose of the present invention is to provide a preparation method of an ITO planar target. By setting a special sliding structure and a heat insulation structure on the supporting plate of the sintering furnace during the sintering process of the target blank, the warping problem of the generated ITO planar target can be effectively suppressed without changing the heating method, and at the same time, no cracking phenomenon will occur.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A preparation method of an ITO planar target, comprising the following steps:

[0006] (1) Place a first-level gasket on the supporting plate of the sintering furnace, then sprinkle a layer of ceramic particles, then place a second-level gasket, and finally sprinkle a layer of metal powder;

[0007] (2) Place the ITO target blank to be sintered on the metal powder, and then annularly place block-shaped alumina around the ITO target blank. The lowest vertical height of the block-shaped alumina is 15 - 20 mm higher than the highest vertical height of the ITO target blank, and the horizontal distance between the block-shaped alumina and the plane of the ITO target blank is 8 - 10 mm;

[0008] (3) Introduce oxygen into the sintering furnace and heat for a degreasing reaction, and then perform sintering to obtain the ITO planar target.

[0009] In the preparation method of the ITO planar target of the present invention, compared with the traditional sintering method of the ITO planar target, a sandwich bearing structure of gasket - ceramic particles - gasket is arranged on the supporting plate. This structure can not only effectively reduce the frictional force generated when the gasket contacts the supporting plate, thereby reducing the influence on the shrinkage of the target during sintering, so that the prepared target will not crack; at the same time, the setting of this structure also has a certain buffering property, so that even if the target blank undergoes a certain shrinkage during the sintering process, it will not cause a large relative displacement, resulting in uneven heating. In addition to the change in the bearing method, the present invention also arranges a ring of block-shaped alumina around the target blank. Alumina itself has a good effect of isolating heat radiation. Therefore, the setting of this block-shaped alumina is equivalent to setting a "protective suit" for the target blank, so that the heat generated by the heating wire in the sintering furnace will not directly heat the target blank in a radiation manner, but undergoes secondary heat conduction under the action of alumina. Such a conduction method can make the target blank evenly heated, so that the warping phenomenon caused by uneven heating and excessive local shrinkage of the target blank can be effectively solved.

[0010] However, the inventor found through experiments that there are certain limitations on the placement height and placement distance of the block-shaped alumina. If the placement height is too low or the placement distance is too far, it cannot form a good "surrounding furnace effect" on the target blank, and the improvement effect on the gradient temperature zone heating is not good; if the placement distance is too close, it may cause the target blank to be unable to exhaust gas effectively during the sintering process, affecting the product quality.

[0011] Preferably, the primary gasket and the secondary gasket are alumina gaskets, and the gap distance between the primary gasket and the secondary gasket is 8 - 10 mm.

[0012] When the bottom bearing gasket also uses the same alumina material as that around the target blank, the heat uniformity of the target blank can be higher. At the same time, when the set spacing is 8 - 10 mm (i.e., the longitudinal average size of the ceramic particle layer is 8 - 10 mm), the structure can be effectively ensured to have a lower frictional force and a higher buffering property.

[0013] Preferably, the metal powder is heat-treated at 1600 - 1800 °C and sieved through a 60 - 100 mesh sieve, and the spreading thickness of the metal powder on the secondary gasket is 1 - 2 mm.

[0014] More preferably, the metal powder is tin oxide powder.

[0015] The main function of this metal powder is to enable the bottom of the target blank to be evenly heated during the heating process and to discharge the reaction gas in a timely manner, without affecting the quality of the bottom part of the product.

[0016] Preferably, the block-shaped alumina is a cuboid.

[0017] Stacked and surrounded by regular block-shaped alumina, the corners and other parts of the target blank can also be evenly heated during the sintering process, so the warpage is lower.

[0018] Preferably, in the step (3), the oxygen inlet amount is 5-20 L / min.

[0019] By introducing oxygen appropriately, the sintering furnace can effectively discharge moisture and additives in the target blank during the degreasing stage, avoiding the influence of these components on the performance of the ITO planar target.

[0020] More preferably, the specific method of heating for the degreasing reaction in the step (3) is: heating at a heating rate of 0.6-2 °C / min to 100-140 °C, holding for 5-15 h in the first stage; then heating at a heating rate of 0.5-1.5 °C / min to 280-320 °C, holding for 10-20 h in the second stage; finally heating at a heating rate of 0.6-1 °C / min to 640-660 °C.

[0021] Through the segmented degreasing reaction, the target blank can remove water vapor and additives more fully. At the same time, the heating degree of the target blank in this process is relatively uniform and stable, and there will be no phenomenon of local overheating, shrinkage and warpage.

[0022] Preferably, in the (3), the specific method of sintering is: first heating the target blank after the degreasing reaction to 1540-1560 °C at a heating rate of 0.6-1 °C / min, and then adjusting the oxygen inlet amount to 20-45 L / min and holding for 10-30 h.

[0023] Another object of the present invention is to provide an ITO planar target prepared by the preparation method of the ITO planar target, and the density of the ITO planar target is 7.135-7.145 g / cm 3 , and the relative density ≥ 99.7%.

[0024] Under the specific sintering process of the present invention, the prepared ITO planar target product has a relatively high density, comparable to existing products. At the same time, it has a low corner warpage, good integrity, and no cracks or fractures.

[0025] The beneficial effect of the present invention is that the present invention provides a preparation method of an ITO planar target. By setting a special sliding structure and a heat insulation structure on the supporting plate of the sintering furnace during the sintering process of the target blank, the warpage problem of the generated ITO planar target can be effectively suppressed without changing the heating method, and there will be no cracking phenomenon at the same time. Detailed implementation mode

[0026] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. The purpose is to understand the content of the present invention in detail, rather than a limitation to the present invention. All other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention. The experimental reagents, raw materials and instruments designed in the embodiments and comparative examples of the present invention are all common ordinary reagents, raw materials and instruments unless otherwise specified.

[0027] The purity of the alumina gaskets used in each embodiment and comparative example of the present invention is ≥93%.

[0028] The target blanks sintered in each embodiment and comparative example of the present invention are obtained by die pressing and cold isostatic pressing of ITO powder in a ratio of 90:10.

[0029] The metal powders used in each embodiment and comparative example of the present invention are tin oxide powders heated at 1800 °C and sieved through a 60 - 100 mesh sieve.

[0030] In each embodiment of the present invention, the number of ITO planar target materials produced each time is 10 pieces, and in the comparative example, it is 5 pieces.

[0031] Example 1

[0032] An embodiment of the preparation method of the ITO planar target material of the present invention, the preparation method includes the following steps:

[0033] (1) Place a 5 - mm - thick first - grade alumina gasket on the supporting plate of the sintering furnace, then sprinkle a layer of ceramic particles with a diameter of 1 mm, then place a 5 - mm - thick second - grade alumina gasket. The gap between the two gaskets is 8 - 10 mm. Finally, sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm;

[0034] (2) Place the ITO target blank to be sintered (800 mm × 600 mm × 15 mm) on the metal powder. Then, place block - shaped alumina cuboids around the ITO target blank. The lowest vertical height of the block - shaped alumina is 15 mm higher than the highest vertical height of the ITO target blank, and the horizontal distance between the block - shaped alumina and the plane of the ITO target blank is 8 - 10 mm;

[0035] (3) Introduce oxygen into the sintering furnace at a flow rate of 10 L / min and heat it up at a heating rate of 1 °C / min to 120 °C, and keep it warm for 10 h in the first stage; then heat it up to 300 °C at a heating rate of 1 °C / min and keep it warm for 15 h in the second stage; finally, heat it up to 650 °C at a heating rate of 0.8 °C / min to complete the debinding reaction. Subsequently, heat the target blank after the debinding reaction to 1550 °C at a heating rate of 0.8 °C / min, then adjust the oxygen flow rate to 30 L / min and keep it warm for 20 h, and cool it down to 1000 °C and stop supplying oxygen to obtain the ITO planar target.

[0036] Example 2

[0037] An embodiment of the preparation method of the ITO planar target described in the present invention. The preparation method includes the following steps:

[0038] (1) Place a first-stage alumina gasket with a thickness of 5 mm on the supporting plate of the sintering furnace, then sprinkle a layer of ceramic particles with a diameter of 1 mm, and then place a second-stage alumina gasket with a thickness of 5 mm. The gap between the two gaskets is 8 - 10 mm. Finally, sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm.

[0039] (2) Place the ITO target blank to be sintered (800 mm × 600 mm × 10 mm) on the metal powder, and then annularly place block-shaped alumina cuboids around the ITO target blank. The lowest vertical height of the block-shaped alumina is 20 mm higher than the highest vertical height of the ITO target blank, and the horizontal distance between the block-shaped alumina and the plane of the ITO target blank is 8 - 10 mm.

[0040] (3) Introduce oxygen into the sintering furnace at a flow rate of 10 L / min and heat it up at a heating rate of 1 °C / min to 120 °C, and keep it warm for 10 h in the first stage; then heat it up to 300 °C at a heating rate of 1 °C / min and keep it warm for 15 h in the second stage; finally, heat it up to 650 °C at a heating rate of 0.8 °C / min to complete the debinding reaction. Subsequently, heat the target blank after the debinding reaction to 1550 °C at a heating rate of 0.8 °C / min, then adjust the oxygen flow rate to 30 L / min and keep it warm for 20 h, and cool it down to 1000 °C and stop supplying oxygen to obtain the ITO planar target.

[0041] Example 3

[0042] An embodiment of the preparation method of the ITO planar target described in the present invention. The preparation method includes the following steps:

[0043] (1) Place a first-grade alumina gasket with a thickness of 5 mm on the supporting plate of the sintering furnace. Subsequently, sprinkle a layer of ceramic particles with a diameter of 1 mm, then place a second-grade alumina gasket with a thickness of 5 mm. The gap between the two gaskets is 8 - 10 mm. Finally, sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm;

[0044] (2) Place the ITO target blank to be sintered (800 mm × 600 mm × 15 mm) on the metal powder. Subsequently, place cuboid-shaped alumina blocks annularly around the ITO target blank. The lowest vertical height of the cuboid-shaped alumina is 15 mm higher than the highest vertical height of the ITO target blank. The horizontal distance between the cuboid-shaped alumina and the ITO target blank is 8 - 10 mm;

[0045] (3) Introduce oxygen into the sintering furnace at a flow rate of 15 L / min and heat it up to 120 °C at a heating rate of 0.8 °C / min, and hold for 15 h in the first stage; subsequently, heat it up to 300 °C at a heating rate of 1.5 °C / min and hold for 20 h in the second stage; finally, heat it up to 650 °C at a heating rate of 0.6 °C / min to complete the debinding reaction. Subsequently, heat the target blank after the debinding reaction to 1550 °C at a heating rate of 1 °C / min. Then, adjust the oxygen input amount to 40 L / min and hold for 25 h. Cool down to 1000 °C and stop supplying oxygen to obtain the ITO planar target.

[0046] Comparative Example 1

[0047] A method for preparing an ITO planar target, the preparation method comprising the following steps:

[0048] (1) Place an alumina gasket with a thickness of 5 mm on the supporting plate of the sintering furnace, and then sprinkle a layer of metal powder with a thickness of 1 - 2 mm;

[0049] (2) The same as in Example 1;

[0050] (3) The same as in Example 1.

[0051] Comparative Example 2

[0052] A method for preparing an ITO planar target, the preparation method comprising the following steps:

[0053] (1) Place a first-grade alumina gasket with a thickness of 5 mm on the supporting plate of the sintering furnace. Subsequently, sprinkle a layer of ceramic particles with a diameter of 1 mm, then place a second-grade alumina gasket with a thickness of 5 mm. The gap between the two gaskets is 8 - 10 mm. Finally, sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm;

[0054] (2) Place the ITO target blank to be sintered (800 mm × 600 mm × 10 mm) on the tin oxide powder;

[0055] (3)Same as Example 1.

[0056] Comparative Example 3

[0057] A method for preparing an ITO planar target, the preparation method comprising the following steps:

[0058] (1) Place a primary alumina gasket with a thickness of 5 mm on the supporting plate of the sintering furnace, and then sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm;

[0059] (2) Place the ITO target blank to be sintered (800 mm × 600 mm × 10 mm) on the tin oxide powder;

[0060] (3)Same as Example 1.

[0061] Comparative Example 4

[0062] A method for preparing an ITO planar target, the preparation method comprising the following steps:

[0063] (1) Sprinkle a layer of ceramic particles with a diameter of 1 mm on the supporting plate of the sintering furnace, then place a secondary alumina gasket with a thickness of 5 mm, and finally sprinkle a layer of tin oxide powder with a thickness of 1 - 2 mm;

[0064] (2)Same as Example 1;

[0065] (3)Same as Example 1.

[0066] Comparative Example 5

[0067] A method for preparing an ITO planar target, which is only different from Example 1 in that the lowest vertical height of the massive alumina is equal to the highest vertical height of the ITO target blank.

[0068] Comparative Example 6

[0069] A method for preparing an ITO planar target, which is only different from Example 1 in that the horizontal distance between the massive alumina and the ITO target blank is 2 - 3 mm.

[0070] Comparative Example 7

[0071] A method for preparing an ITO planar target, which is only different from Example 1 in that the horizontal distance between the massive alumina and the ITO target blank is 15 - 16 mm.

[0072] Effect Example 1

[0073] To verify the quality of the products obtained by the preparation method of the present invention, the ITO planar targets obtained in each example and comparative example were tested for corner warping. An aluminum strip was used during the test, and then a feeler gauge was used to measure the warping of each area around the target. The measurement was taken about every 10 cm, and the maximum warping obtained was recorded. The density and relative density of the products were tested, and at the same time, it was observed whether there were cracks in each product produced, and the range value was statistically counted according to batches.

[0074] The results are shown in Table 1.

[0075] Table 1

[0076] Product Corner warpage (mm) <![CDATA[Density (g / cm 3 )]]> Relative density (%) Whether cracks appear Example 1 01～0.3 7.135～7.139 ＞99.7 No Example 2 0.1～0.3 7.140～7.145 ＞99.7 No Example 3 0.1～0.3 7.136-7.141 ＞99.7 No Comparative example 1 0.1～0.3 7.135～7.139 ＞99.7 Yes Comparative example 2 1～1.5 7.138～7.141 ＞99.7 No Comparative example 3 1～1.3 7.133～7.137 ＞99.7 Yes Comparative example 4 0.1～0.3 7.140～7.145 ＞99.7 Yes Comparative example 5 1.0-1.1 7.135～7.139 ＞99.7 Yes Comparative example 6 0.1～0.5 7.135～7.139 ＞99.6 No Comparative example 7 1～1.5 7.135～7.139 ＞99.7 Yes

[0077] It can be clearly seen from Table 1 that the preparation method of the ITO planar target described in this example produces products with small corner warping degrees, moderate density, large relative density, and no cracks at the same time, and is suitable for sintering target blanks of various heights and sizes. In contrast, the product described in Comparative Example 1 uses a common bearing structure during preparation. Due to the friction between the gasket and the supporting plate, although ring-shaped block alumina is provided, cracks appear in the finally prepared product; although the product of Comparative Example 2 uses the bearing structure described in the present invention, ring-shaped block alumina is not provided around the target blank, and the target blank is unevenly heated by thermal radiation, so the corner warping degree is large; while the product of Comparative Example 3 is completely prepared by the existing process, and the product not only has a large corner warping degree, but also cracks appear. The product of Comparative Example 4 does not introduce the bearing structure of gasket - ceramic particles - gasket. Since the friction coefficient of the supporting plate is much larger than that of the gasket, cracks still appear in the product. The height of the block alumina in the preparation process of the product of Comparative Example 5 is insufficient, and it cannot well improve the heat conduction mode in the furnace, and there is still obvious corner warping in the product; similarly, the product of Comparative Example 7 cannot improve the warping phenomenon. In the preparation process of the product of Comparative Example 6, due to the too tight fit between the block alumina and the target blank, the gas generated by the target blank cannot be discharged in time, resulting in a relatively high local warping degree of the target.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence of the technical solutions of the present invention.

Claims

1. A preparation method of an ITO planar target, characterized in that, It includes the following steps: (1) Place a first-level gasket on the supporting plate of the sintering furnace, then sprinkle a layer of ceramic particles, place a second-level gasket, and finally sprinkle a layer of tin oxide powder; (2) Place the ITO target blank to be sintered on the tin oxide powder, and then annularly place block-shaped alumina around the ITO target blank. The lowest vertical height of the block-shaped alumina is 15-20 mm higher than the highest vertical height of the ITO target blank, and the horizontal distance between the block-shaped alumina and the ITO target blank is 8-10 mm; (3) Pass oxygen into the sintering furnace and heat it to carry out a degreasing reaction, and then carry out sintering to obtain the ITO planar target.

2. The preparation method of the ITO planar target according to claim 1, wherein, The first-level gasket and the second-level gasket are alumina gaskets, and the gap distance between the first-level gasket and the second-level gasket is 8-10 mm.

3. The preparation method of the ITO planar target according to claim 1, characterized in that, The tin oxide powder is subjected to heat treatment at 1600-1800 °C and sieved through a 60-100 mesh sieve, and the spreading thickness of the tin oxide powder on the second-level gasket is 1-2 mm.

4. The preparation method of the ITO planar target as described in claim 1, characterized in that In the step (3), the oxygen input amount is 5-20 L / min.

5. The preparation method of the ITO planar target according to claim 4, characterized in that, The specific method of heating for the degreasing reaction in the step (3) is: heat up at a heating rate of 0.6-2 °C / min to 100-140 °C and keep it warm for 5-15 h in the first stage; then heat up at a heating rate of 0.5-1.5 °C / min to 280-320 °C and keep it warm for 10-20 h in the second stage; finally, heat up at a heating rate of 0.6-1 °C / min to 640-660 °C.

6. The preparation method of the ITO planar target according to claim 1, wherein, In the step (3), the specific sintering method is: first heat the target blank after the degreasing reaction to 1540-1560 °C at a heating rate of 0.6-1 °C / min, and then adjust the oxygen input amount to 20-45 L / min and keep it warm for 10-30 h.