Conductive in2se3 target and method for manufacturing the same

Abstract

The application belongs to the field of semiconductors, and particularly relates to a preparation method of a conductive In2Se3 target material, which comprises the following steps: step 1: mixing Cu2Se powder and In2Se3 powder to obtain mixed powder; step 2: performing die pressing on the mixed powder to obtain a target blank; step 3: in a vacuum furnace, heating to 700-800 DEG C under a vacuum state, then under the vacuum state, heat preservation for 30-60 min; then increasing the pressure in the furnace to 35-40 MPa, heat preservation for 60-90 min; after the heat preservation is completed, pressure reduction and heating stop to obtain the target material; the Cu2Se powder accounts for 2-10% of the total weight of the Cu2Se powder and the In2Se3 powder. The method can obtain a product with a relative density greater than 96%, preferably greater than 97%, a resistance less than 1250 KΩ / cm, and preferably less than 900 KΩ / cm by controlling the doping amount of Cu2Se and through the variable-pressure constant-temperature mode. In addition, the application further provides a conductive In2Se3 target material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductors, in particular to a conductive In2Se3 target material and a preparation method thereof. BACKGROUND

[0002] At present, copper indium gallium selenide (CIGS) thin film solar cells have the characteristics of low production cost, small pollution, no degradation, good weak light performance and other remarkable features. The photoelectric conversion efficiency of CIGS thin film solar cells is the highest among various thin film solar cells, close to that of crystalline silicon solar cells, but the cost is only one third of that of crystalline silicon solar cells, which is a new type of thin film solar cell with great market potential. The buffer layer of CIGS thin film solar cells forms a transition between the low-bandgap CIGS absorber layer and the high-bandgap ZnO window layer, reduces the lattice mismatch and bandgap mismatch of the two, and can prevent damage to the CIGS absorber layer during sputtering of the ZnO window layer, which plays an important role in improving the efficiency of CIGS thin film solar cells. Selenium and indium in the absorber layer are mainly obtained by magnetron sputtering target material. The performance of the absorber film layer is directly related to the density, purity and resistivity of the target material. Conversely, the performance of the target material is most directly related to the particle size distribution, purity and preparation process of the powder. The indium selenide target material prepared by conventional hot pressing process can only make the density of the indium selenide target material reach about 92%, and the resistance is very large, 5-20 MΩ / cm, which causes the performance of the indium selenide film layer formed subsequently to be poor, thereby reflecting a low photoelectric conversion efficiency.

[0003] Chinese patent CN 110256080 A, although the indium selenide target material prepared by the hot isostatic pressing equipment has high density and low resistance, the cost is very expensive, the processing is complicated, the raw material utilization rate is low, and it is not suitable for mass production.

[0004] Chinese patent CN 115741938 A has improved production compared to patent CN 110256080, but still uses hot isostatic pressing, which is expensive and complicated to operate, and also requires high flatness for each layer, which can easily cause the product to break and is not suitable for mass production.

[0005] CN101333645A discloses a process for preparing a copper indium selenide sputtering target material, wherein Cu2Se and In2Se3 powders are mixed in a mass ratio of 1:2.25-1:3 and cold-pressed at a pressure of 200-600 MPa for 1-3 min.

[0006] This scheme does not disclose the conductivity of the target material, and static pressure forming process is required.

[0007] The technical problem to be solved by the present application is how to obtain an indium selenide target material without hot / cold isostatic pressing process and with improved electrical conductivity. SUMMARY

[0008] One of the purposes of the present application is to provide a preparation method of conductive In2Se3 target material; the method can obtain a product with relative density greater than 96%, preferably greater than 97%, resistivity less than 1250KΩ / cm, preferably less than 900KΩ / cm by controlling the doping amount of Cu2Se and through pressure-constant temperature mode.

[0009] In addition, the present application also provides a conductive In2Se3 target material.

[0010] To achieve the above-mentioned purposes, the present application provides a preparation method of conductive In2Se3 target material, characterized in that it comprises the following method:

[0011] Step 1: mixing Cu2Se powder and In2Se3 powder to obtain mixed powder;

[0012] Step 2: molding the mixed powder to obtain a target blank;

[0013] Step 3: heating to 700-800℃ in a vacuum furnace under vacuum state, then keeping vacuum state for 30-60min, then increasing the pressure in the furnace to 35-40MPa and keeping for 60-90min, then reducing the pressure and stopping heating to obtain the target material;

[0014] The Cu2Se powder accounts for 2-10% of the total weight of Cu2Se powder and In2Se3 powder.

[0015] In some embodiments of the present application, the Cu2Se powder accounts for 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the total weight of Cu2Se powder and In2Se3 powder.

[0016] In some embodiments of the present application, the temperature is increased to 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃ under vacuum state.

[0017] In some embodiments of the present application, the holding time under vacuum state is 30min, 35min, 40min, 45min, 50min, 55min, 60min.

[0018] In some embodiments of the present application, the holding time under 35-40MPa is 60min, 65min, 70min, 75min, 80min, 85min, 90min.

[0019] In some embodiments of the present application, the pressure of the pressure-keeping heat preservation is 35 MPa, 36 MPa, 37 MPa, 38 MPa, 39 MPa, 40 MPa.

[0020] In the preparation method of the conductive In2Se3 target material, the size of the Cu2Se powder is: D10 less than 2 microns, D50 less than 5 microns, and D90 less than 10 microns.

[0021] The size of the In2Se3 powder is: D10 less than 5 microns, D50 less than 10 microns, and D90 less than 25 microns.

[0022] Preferably, the size of the Cu2Se powder is: D10: 1.44-1.68 microns; D50: 4.15-3.83 microns; and D90: 8.12-8.39 microns.

[0023] The size of the In2Se3 powder is: D10: 3.46-2.38 microns; D50: 6.47-7.85 microns; and D90: 22.58-20.5 microns.

[0024] It can be seen that the overall particle size of the Cu2Se powder is smaller than that of the In2Se3 powder, which facilitates the embedding of the Cu2Se powder into the voids of the In2Se3 powder, thereby improving the relative density and the uniformity between the two.

[0025] In the preparation method of the conductive In2Se3 target material, the oxygen content of the Cu2Se powder and the In2Se3 powder is less than 700 ppm.

[0026] It should be noted that the particle size of the Cu2Se powder cannot be too small, otherwise it will not be easy to mix with the In2Se3 powder and will cause stratification; the particle size of the Cu2Se powder cannot be too large, otherwise it will be equal to or larger than the In2Se3 powder, which is not conducive to uniform mixing and also not conducive to improving the relative density.

[0027] In the preparation method of the conductive In2Se3 target material, the Cu2Se powder accounts for 5-10% of the total weight of the Cu2Se powder and the In2Se3 powder.

[0028] In the preparation method of the conductive In2Se3 target material, in step 3, the temperature is raised to 700-800°C at a temperature rising rate of 5-10°C / min under vacuum.

[0029] In the preparation method of the conductive In2Se3 target material, in step 2, the pressing pressure is 5-10 MPa.

[0030] The purpose of the pressing pressure is to completely remove the air in the target blank and improve the relative density.

[0031] In the above-mentioned method for preparing conductive In2Se3 target material, the mixing method in step 1 is as follows: Cu2Se powder and In2Se3 powder are first homogenized in a dual-motion mixer, and then homogenized in a three-dimensional homogenizer.

[0032] By combining dual-motion and three-dimensional homogenizers, Cu2Se and In2Se3 can be mixed uniformly and the detection value of Cu2Se in the target material can be controlled within 0.3wt%.

[0033] In the above-mentioned method for preparing conductive In2Se3 target material, the processing technology of the dual-motion mixer is as follows: the rotation speed of the material barrel is set to 15-25 rpm / min, the rotation speed of the spiral blades inside the material barrel is set to 50-70 rpm, and the homogenization time is 1-2 hours.

[0034] In the above-mentioned method for preparing conductive In2Se3 target material, the processing technology of the three-dimensional homogenizer is as follows: the set frequency of the three-dimensional homogenizer is 30-50Hz, and the homogenization time is 1-2h.

[0035] In the above-mentioned method for preparing conductive In2Se3 target material, after step 3, step 4 is performed: the target material obtained in step 3 is ground, tested, and then processed to the specified size according to the drawing to obtain conductive In2Se3 target material.

[0036] Finally, the present invention also discloses a conductive In2Se3 target material, which is prepared by any of the methods described above.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention achieves a product with a relative density greater than 97% and a resistivity less than 900 KΩ / cm by controlling the amount of Cu2Se doping and using a variable pressure isothermal method.

[0039] Verification has shown that if the Cu2Se doping amount is too high, the resistivity cannot be controlled by the method of this invention; if the process is carried out by direct high-pressure isothermal method, the resistivity will be too high.

[0040] The conductive In2Se3 target of this invention has high density, low resistivity, and low hot-pressing temperature, which saves energy costs and achieves good economic benefits. It is suitable for semiconductor coating, reduces costs, and can also meet the needs of mass production, making it worthy of promotion. Detailed Implementation

[0041] The technical solution of the present invention will be further described in detail below, but this does not constitute any limitation on the present invention.

[0042] Example 1

[0043] Step 1: Prepare indium selenide powder and cuprous selenide powder with a purity of 4N5 or higher. Weigh the cuprous selenide powder and indium selenide powder using an electronic balance with an accuracy of 0.1g. Add the cuprous selenide powder to the indium selenide powder.

[0044] The specifications for indium selenide powder are: purity 4N5; D10: 3.46 micrometers, D50: 6.47 micrometers, D90: 20.50 micrometers;

[0045] The specifications of the copper selenide powder are: purity 4N5; D10: 1.44 microns, D50: 3.83 microns, D90: 8.12 microns;

[0046] The cuprous selenide powder comprises 10% of the total weight of the cuprous selenide powder and the indium selenide powder;

[0047] Step 2: The material from Step 1 is placed in a dual-motion mixer - JHTS 5L for homogenization once. The rotation speed of the material tank is set to 25 rpm / min, the rotation speed of the spiral blades inside the material tank is set to 60 rpm, and the homogenization time is 2 hours to complete the first homogenization.

[0048] Then, the material after the first homogenization is placed in a three-dimensional homogenizer - SYH-5, the frequency is set to 40Hz, and a second homogenization is performed for 2 hours;

[0049] Both the first and second homogenizations were carried out in a vacuum environment, with a vacuum level of less than 100 Pa, to eliminate oxygen and moisture from the air.

[0050] Step 3: Place a 0.38mm thick graphite paper into a graphite mold, then spread the homogenized material evenly into the graphite mold with the graphite paper, and then use a tamping hammer to compact the powder to ensure that the initial powder height is as uniform as possible.

[0051] Next, the graphite mold is placed flat and stably into the vacuum hot press furnace using a lifting platform, so that the pressure column and the center of the mold are aligned. First, the descent rate of the pressure head is controlled at 0.05-0.1 mm / s to achieve a pre-pressure of 5-10 MPa to remove air from the graphite mold. After holding for 10-30 minutes, the pressure is released to obtain the indium selenide doped blank.

[0052] Step 4: Close the furnace door and evacuate the furnace until the vacuum level reaches 5-10 Pa. Then, start heating and raise the temperature to 800°C at a rate of 5°C / min. Hold the temperature for 150 min. The specific steps of the holding process are as follows: after holding for 60 min, start pressurizing and then hold the temperature and pressure at 45 MPa for 90 min. After the holding and pressure process is completed, slowly reduce the pressure to 10 MPa and allow the furnace to cool. Open the furnace door and demold to obtain the indium selenide doped blank.

[0053] Step 5: Grind the blank target material and test its density, composition and purity to obtain a doped indium selenide target material with uniform composition and purity greater than 4N5.

[0054] Example 2

[0055] Step 1: Prepare indium selenide powder and cuprous selenide powder with a purity of 4N5 or higher. Weigh the cuprous selenide powder and indium selenide powder using an electronic balance with an accuracy of 0.1g. Add the cuprous selenide powder to the indium selenide powder.

[0056] The specifications of indium selenide powder are: purity 4N5; D10: 2.38 micrometers, D50: 7.85 micrometers, D90: 21.62 micrometers;

[0057] The specifications of cuprous selenide powder are: purity 4N5; D10: 1.66 microns, D50: 4.02 microns, D90: 8.32 microns;

[0058] The cuprous selenide powder comprises 5% of the total weight of the cuprous selenide powder and the indium selenide powder;

[0059] Step 2: The material from Step 1 is placed in a dual-motion mixer - JHTS5L for homogenization once. The rotation speed of the material tank is set to 15 rpm / min, the rotation speed of the spiral blades inside the material tank is set to 50 rpm, and the homogenization time is 1.5 hours to complete the first homogenization.

[0060] Then, the material after the first homogenization was placed in a three-dimensional homogenizer - SYH-5, and the frequency was set to 30Hz for a second homogenization, which lasted for 1.5 hours.

[0061] Both the first and second homogenizations were carried out in a vacuum environment, with a vacuum level of less than 100 Pa, to eliminate oxygen and moisture from the air.

[0062] Step 3: Place a 0.38mm thick graphite paper into a graphite mold, then spread the homogenized material evenly into the graphite mold with the graphite paper, and then use a tamping hammer to compact the powder to ensure that the initial powder height is as uniform as possible.

[0063] Next, the graphite mold is placed flat and stably into the vacuum hot press furnace using a lifting platform, so that the pressure column and the center of the mold are aligned. First, the descent rate of the pressure head is controlled at 0.05-0.1 mm / s to achieve a pre-pressure of 5-10 MPa to remove air from the graphite mold. After holding for 10-30 minutes, the pressure is released to obtain the indium selenide doped blank.

[0064] Step 4: Close the furnace door and evacuate the furnace until the vacuum level reaches 5-10 Pa. Then, start heating at 10℃ / min to 750℃ and hold for 130 min. The specific steps of the holding process are as follows: after holding for 60 min, start pressurizing and then hold for 42 MPa for 70 min. After holding for 70 min, slowly reduce the pressure to 10 MPa and allow the furnace to cool. Open the furnace door and demold to obtain the indium selenide doped blank.

[0065] Step 5: Grind the blank target material and test its density, composition and purity to obtain a doped indium selenide target material with uniform composition and purity greater than 4N5.

[0066] Example 3

[0067] Step 1: Prepare indium selenide powder and cuprous selenide powder with a purity of 4N5 or higher. Weigh the cuprous selenide powder and indium selenide powder using an electronic balance with an accuracy of 0.1g. Add the cuprous selenide powder to the indium selenide powder.

[0068] The specifications for indium selenide powder are: purity 4N5; D10: 3.12 micrometers, D50: 7.24 micrometers, D90: 22.58 micrometers;

[0069] The specifications of cuprous selenide powder are: purity 4N5; D10: 1.68 microns, D50: 4.15 microns, D90: 8.39 microns;

[0070] The cuprous selenide powder comprises 2% of the total weight of the cuprous selenide powder and the indium selenide powder;

[0071] Step 2: The material from Step 1 is placed in a dual-motion mixer - JHTS5L for homogenization once. The rotation speed of the material barrel is set to 15 rpm / min, the rotation speed of the spiral blades inside the material barrel is set to 50 rpm, and the homogenization time is 1 hour to complete the first homogenization.

[0072] Then, the material after the first homogenization is placed in a three-dimensional homogenizer - SYH-5, the frequency is set to 50Hz, and a second homogenization is performed for 1 hour;

[0073] Both the first and second homogenizations were carried out in a vacuum environment, with a vacuum level of less than 100 Pa, to eliminate oxygen and moisture from the air.

[0074] Step 3: Place a 0.38mm thick graphite paper into a graphite mold, then spread the homogenized material evenly into the graphite mold with the graphite paper, and then use a tamping hammer to compact the powder to ensure that the initial powder height is as uniform as possible.

[0075] Next, the graphite mold is placed flat and stably into the vacuum hot press furnace using a lifting platform, so that the pressure column and the center of the mold are aligned. First, the descent rate of the pressure head is controlled at 0.05-0.1 mm / s to achieve a pre-pressure of 5-10 MPa to remove air from the graphite mold. After holding for 10-30 minutes, the pressure is released to obtain the indium selenide doped blank.

[0076] Step 4: Close the furnace door and evacuate the furnace until the vacuum level reaches 5-10 Pa. Then, start heating at 10℃ / min to 700℃ and hold for 120 minutes. The specific steps of the holding process are as follows: after holding for 60 minutes, start pressurizing and then hold for 40 MPa for 60 minutes. After the holding is completed, slowly reduce the pressure to 10 MPa and allow the furnace to cool. Open the furnace door and demold to obtain the indium selenide doped blank.

[0077] Step 5: Grind the blank target material and test its density, composition and purity to obtain a doped indium selenide target material with uniform composition and purity greater than 4N5.

[0078] Example 4

[0079] Generally the same as Example 1, except that:

[0080] Step 2: The material from Step 1 is placed in a dual-motion mixer - JHTS5L for homogenization once. The rotation speed of the material barrel is set to 25 rpm / min, the rotation speed of the spiral blades inside the material barrel is set to 60 rpm, and the homogenization time is 2 hours to complete the homogenization.

[0081] No three-dimensional homogenization is performed.

[0082] Homogenization is carried out in a vacuum environment, with a vacuum level of less than 100 Pa, to eliminate oxygen and moisture from the air.

[0083] Example 5

[0084] Generally the same as Example 1, except that:

[0085] Step 2: Place the material from Step 1 into a 3D homogenizer - SYH-5, set the frequency to 40Hz, and homogenize for 2 hours;

[0086] Homogenization is not performed using a dual-motion mixer.

[0087] Homogenization is carried out in a vacuum environment, with a vacuum level of less than 100 Pa, to eliminate oxygen and moisture from the air.

[0088] Example 6

[0089] Indium selenide powder and cuprous selenide powder have similar specifications, namely: purity 4N5; D10: 1.7±0.2 microns, D50: 4.2±0.5 microns, and D90: 8.5±1 microns.

[0090] Comparative Example 1

[0091] Generally the same as Example 1, except that:

[0092] Step 4: Close the furnace door and evacuate the furnace until the vacuum level reaches 5-10 Pa. Start heating and raise the temperature to 800℃ at 5℃ / min. Hold the temperature and pressure for 150 min. The furnace pressure is 45 MPa. After the holding and pressure is completed, slowly reduce the pressure to 10 MPa and allow the furnace to cool. Open the furnace door and demold to obtain the indium selenide doped blank.

[0093] Comparative Example 2

[0094] Generally the same as Example 1, except that:

[0095] Step 4: Close the furnace door and evacuate the furnace until the vacuum level inside the furnace reaches 5-10 Pa. Start heating and raise the temperature to 800℃ at a rate of 5℃ / min. Hold the temperature for 150 minutes under vacuum. After the holding period, slowly increase the pressure to atmospheric pressure and allow the furnace to cool. Open the furnace door and demold to obtain the indium selenide doped blank.

[0096] Comparative Example 3

[0097] Generally the same as Example 3, except that:

[0098] The cuprous selenide powder accounts for 1% of the total weight of the cuprous selenide powder and indium selenide powder.

[0099] Performance testing

[0100] Test item 1: Density; Test method: Detection using Archimedes' principle.

[0101] Test item 2: Resistance; Test method: Use a multimeter for testing.

[0102] Test item 3: Purity, Test method: ICP-OES (inductively coupled plasma-optical mission spectroscopy) instrument is used for testing;

[0103] Test item 4: Oxygen content; Test method: Oxygen analyzer (model LECO RO600) was used for testing.

[0104] The test results are shown in Tables 1 and 2 below;

[0105] Table 1 Test Results

[0106] Relative density Resistance KΩ / cm O ppm Example 1 97.1％ 875 640 Example 2 97.4％ 786 623 Example 3 97.6％ 813 597 Example 4 96.8％ 1123 652 Example 5 96.2％ 1232 639 Example 6 96.1％ 987 645 Comparative Example 1 97.2％ 1002 652 Comparative Example 2 78.5％ 3485 663 Comparative Example 3 97.2％ 1056 673

[0107] Table 2 Test Results

[0108]

[0109] Results analysis:

[0110] 1. As can be seen from the comparison of Examples 1-3 and Comparative Example 3, the content of cuprous selenide powder has no significant effect on the relative density, but has a more significant effect on the resistivity. The content of cuprous selenide powder in Examples 1-3 and Comparative Example 3 gradually decreased, and the resistivity first decreased and then increased. Therefore, the optimal content of cuprous selenide powder is in the range of 2-5%.

[0111] 2. As can be seen from the comparison of Examples 1, 4 and 5, two mixing and homogenization is an important means of reducing resistivity. In other words, thorough mixing is beneficial to the control of resistivity.

[0112] 3. As can be seen from the comparison of Examples 1 and 6, the particle size of indium selenide powder is preferably larger than that of cuprous selenide powder. When the particle sizes of the two are similar, it is not conducive to the control of resistivity or the improvement of relative density.

[0113] 4. As can be seen from the comparison of Example 1, Comparative Example 1 and Comparative Example 2, vacuum heat preservation for a period of time followed by pressure during sintering has a significant contribution to reducing the resistivity of the product.

[0114] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method of producing an electrically conductive In2Se3 target material, characterized by, The method comprises the following steps: Step 1: mixing Cu2Se powder and In2Se3 powder to obtain mixed powder; Step 2: performing die pressing on the mixed powder to obtain a target blank; Step 3: in a vacuum furnace, heating to 700-800℃ under vacuum, then under vacuum, maintaining for 30-60min; then increasing the pressure in the furnace to 35-40MPa, maintaining for 60-90min; after the maintaining, decreasing the pressure and stopping heating to obtain the target material; The Cu2Se powder accounts for 2-10% of the total weight of the Cu2Se powder and the In2Se3 powder; The mixing method in step 1 is: first homogenizing the Cu2Se powder and the In2Se3 powder in a double-motion mixer, and then homogenizing in a three-dimensional homogenizer; In step 3, heating to 700-800℃ at a heating rate of 5-10℃ / min under vacuum; The specification of the Cu2Se powder is: D10 less than 2 microns, D50 less than 5 microns, and D90 less than 10 microns; The specification of the In2Se3 powder is: D10 less than 5 microns, D50 less than 10 microns, and D90 less than 25 microns; The oxygen content of the Cu2Se powder and the In2Se3 powder is less than 700ppm; The relative density of the conductive In2Se3 target material is greater than 97%, and the resistivity is less than 900kΩ / cm.

2. The method of claim 1, wherein the method further comprises: The Cu2Se powder accounts for 5-10% of the total weight of the Cu2Se powder and the In2Se3 powder.

3. The method of claim 1, wherein the method further comprises: In step 2, the die pressing pressure is 5-10MPa.

4. The method of claim 1, wherein the method further comprises: The processing technology of the double-motion mixer is: the rotation speed of the material barrel is set to 15-25rpm, the rotation speed of the screw blade inside the material barrel is set to 50-70rpm, and the homogenizing time is 1-2h.

5. The method of claim 1, wherein the method further comprises: The processing technology of the three-dimensional homogenizer is: the set frequency of the three-dimensional homogenizer is 30-50Hz, and the homogenizing time is 1-2h.

6. The method of claim 1, wherein the method further comprises: After step 3, step 4 is further performed: grinding the target material obtained in step 3, performing detection, and then processing to the specified size according to the drawing to obtain the conductive In2Se3 target material.

7. A conductive In2Se3 target material, characterized by, The conductive In2Se3 target material is prepared by the method according to any one of claims 1-6.

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