Large-sized indium zinc oxide target and method for manufacturing the same

Abstract

The application belongs to the technical field of semiconductors, and discloses a preparation method of a large-size indium zinc oxide target material, which comprises the following steps: step 1, sintering an indium zinc oxide target blank at 600-800 DEG C; step 2, placing two or more indium zinc oxide target blanks treated in step 1 side by side, with a gap between the two adjacent indium zinc oxide target blanks; step 3, injecting a thermoplastic slurry into the gap, wherein the slurry contains indium zinc oxide powder; and step 4, sintering at 1500-1600 DEG C to obtain the indium zinc oxide target material. The method uses a thermoplastic slurry as a bonding material, and the target blank is sintered at a low temperature before bonding, so that the target material particles can be preliminarily combined to prevent the target material from collapsing, and the target material can be sintered at a high temperature after bonding to obtain a large-size indium zinc oxide target material with a high qualification rate. Meanwhile, the application also provides the large-size indium zinc oxide target material.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to a large-size indium zinc oxide target and its preparation method. Background Technology

[0002] Sputtering targets are fundamental consumables in the magnetron sputtering process, used in large quantities, and their quality plays a crucial role in determining the performance of thin films. Targets have a wide range of applications, including optical targets, display thin film targets, semiconductor targets, recording media targets, and superconducting targets. Among these, semiconductor, display, and recording media targets are the three most widely used. To improve the thin film preparation rate and ensure the growth quality of the thin film, sputtering targets must meet certain performance requirements. In recent years, flat panel display technologies such as liquid crystal displays, active organic light-emitting diode displays, and flexible displays have developed rapidly, making the importance of thin film transistors (TFTs) as core components self-evident. Among these, oxide semiconductor-based TFTs have attracted widespread attention due to their advantages such as high mobility, good electrical uniformity, high visible light transmittance, low preparation temperature, and low cost.

[0003] Small-sized indium zinc oxide (IZO) sputtering targets are relatively easy to manufacture, while large-sized IZO sputtering targets are more difficult to manufacture. This is because large-sized IZO sputtering targets are subject to greater stress during sintering, which can cause the edges to warp.

[0004] Large-sized indium zinc oxide (IZO) sputtering targets offer certain processing advantages. In existing technologies, IZO sputtering typically involves placing multiple small IZO targets side-by-side for sputtering operations. However, this method has drawbacks: air and impurities may remain at the seams, leading to blackening and nodulation. Therefore, the preparation of large-sized IZO targets is urgently needed.

[0005] Using multiple small-sized targets to form a large-sized target is an option. Specifically, CN112624785A discloses a method for preparing large-sized oxide targets by splicing oxide slurry and secondary sintering. This method involves bonding smaller-sized oxide targets with oxide slurry, pressing and drying them, and then sintering them a second time to prepare large-sized targets.

[0006] More specifically, it includes the following steps:

[0007] 1) Preparation of high-quality oxide slurry;

[0008] 2) Based on the requirements, different splicing schemes for different shaped targets are designed to splice small target pieces, and then the oxide slurry is bonded.

[0009] 3) Press and fix the bonding joints of the target material and dry them;

[0010] 4) Further sinter the bonded large-size oxide target material;

[0011] 5) After processing and polishing, a large-sized oxide target material is obtained.

[0012] It further describes: the bonded large-size oxide target material is further sintered: first, the oxide slurry is degreased by holding it at 500℃ for 4-10 hours, then it is sintered at 1400-1600℃ under normal pressure in an oxygen environment for 5-8 hours, and then cooled down to room temperature with the furnace. The binder used is polyvinyl alcohol binder, which is a thermoplastic material.

[0013] It is evident that the sintering process takes place after the splicing.

[0014] This operation has the following problems: using slurry for bonding may cause the edges of the target material used for splicing to fall apart, resulting in a decrease in density at the splice joints of the target material.

[0015] At the same time, the jointing mortar used in this case had a low concentration and was not suitable for forming a proper joint.

[0016] Therefore, the technical problem to be solved in this case is: how to obtain large-size indium zinc oxide sputtering targets with a high yield rate. Summary of the Invention

[0017] One of the objectives of this invention is to provide a method for preparing large-size indium zinc oxide targets. This method uses a thermoplastic slurry as a binder. Before bonding, the target blank is sintered at low temperature, which allows the target particles to be initially bonded and prevents the target from collapsing. After bonding, high-temperature sintering is performed to obtain large-size indium zinc oxide targets with a high yield.

[0018] Meanwhile, the present invention also provides this large-size indium zinc oxide target.

[0019] Unless otherwise specified in this invention, M stands for mol / L and % stands for mass percentage.

[0020] To achieve the above objectives, the present invention provides a method for preparing a large-size indium zinc oxide target, comprising the following steps:

[0021] Step 1: Sinter the indium zinc oxide target blank at 600-800℃;

[0022] Step 2: Place two or more indium zinc oxide target blanks obtained in Step 1 side by side, with a gap between adjacent indium zinc oxide target blanks;

[0023] Step 3: Inject a thermoplastic slurry containing indium zinc oxide powder into the gap;

[0024] Step 4: Sinter at 1500-1600℃ to obtain indium zinc oxide target material.

[0025] In the above-described method for preparing large-size indium zinc oxide targets, the amount of thermoplastic binder added is 35% to 55% of the total mass of indium zinc oxide powder.

[0026] In the above-described method for preparing large-size indium zinc oxide targets, the remaining component in the slurry is a thermoplastic binder.

[0027] In the above-mentioned method for preparing large-size indium zinc oxide targets, the thermoplastic binder is one or two of high-density polyethylene, polyvinyl acetal, and ethylene-vinyl acetate copolymer resin.

[0028] In the above-described method for preparing large-size indium zinc oxide targets, the gap is 0.5–2 cm.

[0029] And / or, the indium zinc oxide target blank has a size of 50*50mm to 300*500mm.

[0030] In the above-mentioned method for preparing large-size indium zinc oxide targets, the sintering time in step 1 is 6 to 12 hours.

[0031] And / or, the heating rate in step 1 is 1 to 3 °C / min.

[0032] In the above-described method for preparing large-size indium zinc oxide targets, the sintering time in step 4 is 8 to 10 hours.

[0033] And / or, the heating rate in step 4 is 1 to 3 °C / min.

[0034] In the above-mentioned method for preparing large-size indium zinc oxide targets, the mass ratio of indium oxide to zinc oxide in the indium zinc oxide target blank and indium zinc oxide powder is 77.5-93.2:6.8-22.5.

[0035] In the above-described method for preparing large-size indium zinc oxide targets, the raw materials used for the indium zinc oxide target blank and the indium zinc oxide powder are all prepared by the following method:

[0036] Step a: Weigh out a certain amount of indium oxide powder and zinc oxide powder;

[0037] Step b: Add pure water to the slurry tank, and add the weighed zinc oxide powder and the first dispersant from step a to the mixing tank for pre-dispersion. The pre-dispersion time is 20-40 minutes, and the dispersion speed is 60-200 rpm. The first dispersant accounts for 1-5% of the total mass of the added zinc oxide powder, pure water, and first dispersant. The first dispersant is polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, or sodium hexadecylbenzenesulfonate.

[0038] Step c: The slurry obtained in step b is pumped into a sand mill by a pneumatic diaphragm pump for grinding. The grinding time is 10-22 hours, the grinding speed is 1200-1800 r / min, and the solid content in the slurry is between 60-70%, to obtain slurry one.

[0039] Step d: Add indium oxide powder and a second dispersant to the slurry obtained in step c. The pre-dispersion time is 20-40 min and the rotation speed is 60-200 rpm. The obtained slurry is then pumped into a sand mill using a pneumatic diaphragm pump for grinding. After grinding for 8-15 h, slurry two is obtained. The second dispersant accounts for 1-15% of the total mass of the added indium oxide powder and the second dispersant. The grinding speed is 1200-1800 r / min. The solid content in the slurry is between 60-70%. The second dispersant is polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, or sodium hexadecylbenzenesulfonate.

[0040] Step e: After adding the binder to slurry two obtained in step d, pre-dispersion is performed for 20–40 min at a dispersion speed of 60–200 rpm. The resulting slurry is then pumped into a sand mill using a pneumatic diaphragm pump for grinding. After grinding for 2–4 h, slurry three is obtained. The grinding speed is 1200–1800 r / min, and the binder accounts for 5–15% of the total mass of the added powder and binder. The binder is one or two of the following: a mixture of polyvinyl alcohol and polyethylene glycol, polyvinyl alcohol, or polyvinyl butyral.

[0041] Step f: The slurry obtained in step e is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain indium zinc oxide mixed powder; wherein, the outlet air temperature is 70-85℃ and the atomizer frequency is 120Hz.

[0042] The preparation method of the indium zinc oxide target blank is as follows: the indium zinc oxide mixed powder is molded and cold isostatically pressed to obtain the indium zinc oxide target blank.

[0043] Meanwhile, the present invention also discloses a large-size indium zinc oxide target material, which is prepared by any of the methods described above; the size of the large-size indium zinc oxide target material is 50*100mm~300*500mm.

[0044] Beneficial effects

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] This invention uses a thermoplastic slurry as a bonding material. The target blank is sintered at low temperature before bonding, which can make the target particles initially bonded and prevent the target from collapsing. After bonding, high temperature sintering can be performed to obtain large-size indium zinc oxide targets with a high yield rate, while the appearance of the joints is not significantly different. Detailed Implementation

[0047] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0048] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

[0049] Example 1

[0050] Step 1: Weigh out indium oxide and zinc oxide powders according to a mass ratio of 77.5:22.5 and set aside.

[0051] Step 2: Add a certain amount of pure water to the slurry tank, and add the zinc oxide powder and PVP weighed in step (1) to the slurry tank for pre-dispersion. The dispersion time is 30 min and the dispersion speed is 100 rpm. PVP accounts for 4% of the total mass of zinc oxide powder, pure water and PVP added.

[0052] Step 3: The slurry obtained in Step 2 is pumped into a sand mill using a pneumatic diaphragm pump for grinding. The grinding time is 12 hours and the grinding speed is 1500 r / min, to obtain slurry one.

[0053] Step 4: Add indium oxide powder and PVP to the slurry obtained in Step 3 and disperse for 30 minutes at a speed of 100 rpm. Then, use a pneumatic diaphragm pump to feed the resulting slurry into a sand mill for grinding for 8 hours at a speed of 1500 rpm to obtain slurry two. PVP accounts for 4% of the total mass of the added indium oxide powder and PVP.

[0054] Step 5: PVA is added to slurry two obtained in step 4, and then pre-dispersed for 30 minutes at a dispersion speed of 100 rpm. The slurry is then pumped into a sand mill using a pneumatic diaphragm pump for grinding for 2 hours at a grinding speed of 1500 rpm, yielding slurry three. The binder constitutes 10% of the total mass of the added indium oxide powder, zinc oxide, and binder.

[0055] Step 6: The slurry obtained in Step 5 is fed into a spray drying tower for spray granulation, followed by mixing and sieving to obtain indium aluminum oxide mixed powder. The outlet air temperature is 75℃, and the atomizer frequency is 120Hz.

[0056] Step 7: The mixed powder obtained in step (6) is molded and cold isostatically pressed to obtain indium zinc oxide target blank.

[0057] The molding process is as follows: after filling the 50*300mm mold with mixed powder, it is placed in a hydraulic press and hydraulically pressed at a pressure of 50Mpa. After demolding, indium zinc oxide target blanks are obtained.

[0058] The process parameters for cold isostatic pressing are as follows: the obtained indium zinc oxide target blank is placed in a soft packaging film, which is generally made of PE plastic bag. The sealed bag is placed in a cold isostatic press and immersed in a liquid pressure medium. The high-pressure liquid injected by the high-pressure pump is used for pressing, and the pressure is 360MPa to obtain the indium zinc oxide target blank.

[0059] Step 8: Place the target blank obtained in step (7) into a sintering furnace for low-temperature sintering. The heating rate is 3℃ / min. Heat to 800℃ and hold for 8 hours. Then cool down to room temperature to obtain the target material.

[0060] Step 9: After cooling the target material obtained in step (8), use a mold to splice the target material together, with a gap width of 1mm;

[0061] Step 10: Take out a portion of the indium zinc oxide mixed powder obtained in step (6), add a binder to it, the binder is thermoplastic high-density polyethylene; disperse it for 30 min at a speed of 100 rpm to obtain a mixture;

[0062] The weight ratio of the binder and zinc indium oxide powder is 1:2;

[0063] Step 11: After the mixture obtained in step (10) is mixed evenly, it is added to the mixer of the powder injection molding machine. It is heated into a rheological plastic material in the injection barrel of the injection machine at a heating temperature of 150°C, and then sprayed out through the nozzle at a temperature of 200°C. After the seam is filled, the injection is stopped, and after waiting for 10 minutes, the large-size indium zinc oxide target is demolded.

[0064] Step 12: Sinter the target blank obtained in step (11) at a temperature of 1600℃ (holding time 10 hours, heating rate 3℃ / min), and obtain the target material after cooling.

[0065] The target material was free of cracks after being taken out of the furnace. After processing and polishing, a large-sized indium zinc oxide target material with a specification of 50*600mm was obtained.

[0066] Example 2

[0067] It is largely the same as Example 1, except that the ratio of indium oxide to zinc oxide is 93.2:6.8.

[0068] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0069] Example 3

[0070] It is largely the same as Example 1, except that the ratio of indium oxide to zinc oxide is 95:15.

[0071] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0072] Example 4

[0073] The process is largely the same as in Example 1, except that in step 10, the weight ratio of the binder and zinc indium oxide mixed powder in the slurry is 2:5.

[0074] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0075] Example 5

[0076] The process is largely the same as in Example 1, except that in step 10, the weight ratio of the binder and zinc indium oxide mixed powder in the slurry is 11:20.

[0077] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0078] Example 6

[0079] The method is largely the same as in Example 1, except that in step 9, the width of the gap is 2 mm.

[0080] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0081] Example 7

[0082] The method is largely the same as in Example 1, except that in step 9, the width of the gap is 1.5 mm.

[0083] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0084] Example 8

[0085] The general structure is the same as in Example 1, except that the indium zinc oxide target blank has a size of 300*400mm.

[0086] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0087] Example 9

[0088] The process is largely the same as in Example 1, except that the indium zinc oxide target blank has a size of 300*300mm.

[0089] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0090] Example 10

[0091] The process is largely the same as in Example 1, except that the sintering temperature in step 8 is 700°C and the sintering time is 12 hours; the heating rate in step 8 is 2°C / min.

[0092] The sintering temperature in step 12 is 1500℃, the holding time is 8 hours, and the heating rate is 1℃ / min.

[0093] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0094] Example 11

[0095] The process is largely the same as in Example 1, except that the sintering temperature in step 8 is 600°C and the sintering time is 6 hours; the heating rate in step 8 is 1°C / min.

[0096] The sintering temperature in step 12 is 1550℃, the holding time is 9 hours, and the heating rate is 2℃ / min.

[0097] The target material after being taken out of the furnace is free of cracks. After processing and polishing, a large-size indium zinc oxide target material is obtained.

[0098] Comparative Example 1

[0099] The process is largely the same as in Example 1, except that step 8 is omitted and the indium zinc oxide target blank obtained in step 6 directly enters step 9, where a mold is used to splice the indium zinc oxide target blank.

[0100] In step 12, the temperature is first increased to 800℃ at a rate of 3℃ / min and held for 8 hours, and then increased to 1600℃ at a rate of 3℃ / min and held for 10 hours.

[0101] The edges of the target blank at the joint after it comes out of the furnace are uneven and warped, and there are cracks at the joint.

[0102] This indicates that low-temperature sintering is necessary before injecting slurry into the gaps, as it can preliminarily shape the target and prevent subsequent deformation of the target edge due to heating and extrusion of the slurry.

[0103] This further demonstrates that the method of the present invention can achieve crack-free target material after high-temperature sintering.

[0104] Comparative Example 2

[0105] It is largely the same as Example 1, except that the sintering temperature in step 8 is 1000°C.

[0106] A sintering temperature of 1000℃ will cause the target blank to begin to shrink. If splicing is then carried out, the target material will be missized, and the shrinkage of the target blank and the joint will be asynchronous.

[0107] This indicates that the temperature of low-temperature sintering cannot be too high. If the temperature is too high, the target material will not be able to be spliced ​​flat.

[0108] Comparative Example 3

[0109] It is largely the same as Example 1, except that the sintering temperature in step 8 is 400°C.

[0110] The edges of the target blank at the joint after it comes out of the furnace are uneven and warped, and there are cracks at the joint.

[0111] This indicates that the temperature of low-temperature sintering cannot be too low. If the temperature is too low, it will lead to poor initial shaping. Subsequently, the deformation of the target edge caused by the slurry will squeeze the target blank, resulting in warping.

[0112] Meanwhile, we have tested that when the binder content is less than 35% (equivalent to the total mass of indium zinc oxide powder), it cannot effectively disperse the indium zinc oxide mixed powder, resulting in unstable connection between adjacent target blanks.

[0113] If the amount of binder is higher than 55% (equivalent to the total mass of indium zinc oxide powder), the amount of powder after sintering will be too small to fill the gaps and form a stable bond.

[0114] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A method for preparing a large-size indium zinc oxide target, characterized in that, The method comprises the following steps: Step 1: sintering the indium zinc oxide target blank at 600-800℃; Step 2: placing two or more indium zinc oxide target blanks treated in step 1 side by side with a gap between adjacent indium zinc oxide target blanks; Step 3: injecting a thermoplastic slurry into the gap, wherein the slurry is composed of indium zinc oxide powder and a thermoplastic binder; Step 4: sintering at 1500-1600℃ to obtain an indium zinc oxide target material; The amount of the thermoplastic binder added is 35%-55% of the total mass of the indium zinc oxide powder; the mass ratio of indium oxide and zinc oxide in the indium zinc oxide target blank and the indium zinc oxide powder is 77.5-93.2:6.8-22.

5.

2. The method of producing a large-sized indium zinc oxide target according to claim 1, wherein The thermoplastic binder is one or two of high-density polyethylene, polyvinyl acetal and ethylene-vinyl acetate copolymer resin.

3. The method of producing a large-sized indium zinc oxide target according to claim 1, wherein The gap is 0.5-2cm; And / or, the size of the indium zinc oxide target blank is 50*50mm-300*500mm.

4. The method of producing a large-sized indium zinc oxide target according to claim 1, wherein The sintering time of step 1 is 6-12h; And / or, the temperature rising speed of step 1 is 1-3℃ / min.

5. The method of producing a large-sized indium zinc oxide target according to claim 1, wherein The sintering time of step 4 is 8-10h; And / or, the temperature rising speed of step 4 is 1-3℃ / min.

6. The method of producing a large-sized indium zinc oxide target according to claim 1, wherein The raw materials used in the indium zinc oxide target blank and the indium zinc oxide powder are prepared by the following method: Step a: weighing a certain amount of indium oxide powder and zinc oxide powder; Step b: adding pure water into a slurry barrel, and then adding the weighed zinc oxide powder and a first dispersant into a mixing barrel for pre-dispersion; the pre-dispersion time is 20-40min, and the dispersion rotation speed is 60-200rpm; the first dispersant accounts for 1-5% of the total mass of the added zinc oxide powder, pure water and the first dispersant; the first dispersant is polyvinylpyrrolidone, sodium dodecylbenzenesulfonate or sodium hexadecylbenzenesulfonate; Step c: grinding the slurry obtained in step b into a sand mill by a pneumatic diaphragm pump to obtain slurry one; the grinding time is 10-22h, wherein the grinding rotation speed is 1200-1800r / min, and the solid content in the slurry is between 60-70%; Step d: adding indium oxide powder and a second dispersant to the slurry one obtained in step c for pre-dispersion; the pre-dispersion time is 20-40min, and the rotation speed is 60-200rpm; grinding the obtained slurry into a sand mill by a pneumatic diaphragm pump to obtain slurry two after grinding for 8-15h; wherein the second dispersant accounts for 1-15% of the total mass of the added indium oxide powder and the second dispersant; the grinding rotation speed is 1200-1800r / min; the solid content in the slurry is between 60-70%; the second dispersant is polyvinylpyrrolidone, sodium dodecylbenzenesulfonate or sodium hexadecylbenzenesulfonate; and slurry two is obtained. Step e: after adding the binder to the slurry two obtained in step d, pre-dispersing is performed, the pre-dispersing time is 20-40 min, and the dispersing rotation speed is 60-200 rpm; the obtained slurry is pumped into a sand mill by a pneumatic diaphragm pump to perform grinding, and the slurry three is obtained after grinding for 2-4 h; wherein the grinding rotation speed is 1200-1800 r / min, the binder accounts for 5-15% of the total mass of the added powder and the binder, and the binder is one or both of a mixture of polyvinyl alcohol and polyethylene glycol, polyvinyl alcohol, or polyvinyl butyral; Step f: the slurry three obtained in step e is pumped into a spray drying tower to perform spray granulation, and then mixing and screening are performed to obtain the indium zinc oxide mixed powder; wherein the air outlet temperature is 70-85℃, and the atomizer frequency is 120 Hz; The preparation method of the indium zinc oxide target blank is as follows: the indium zinc oxide mixed powder is subjected to die pressing and cold isostatic pressing to obtain the indium zinc oxide target blank.

7. A large-sized indium zinc oxide target material, characterized by comprising: an indium zinc oxide target material having a diameter of 550 mm or more and a thickness of 5 mm or more. The large-size indium zinc oxide target material is prepared by the method according to any one of claims 1-6; and the specification of the large-size indium zinc oxide target material is 50*100 mm-300*500 mm.