Gold beryllium alloy evaporation material for semiconductor and preparation method thereof

Abstract

The application discloses a kind of gold beryllium alloy evaporation material for semiconductor and preparation method thereof, comprising the following steps: S1, preparing raw material Au and Be, the purity of raw material Au is ≥99.99%, the purity of raw material Be is ≥99.9%;S2, under non-vacuum condition, raw material Au is put into crucible and heated to smelt, after raw material Au is completely melted, heat preservation is carried out between 1080-1400 ℃, after the surface of gold liquid is stable, raw material Be is put into gold liquid, after setting time, the obtained gold beryllium alloy melt is formed, and gold beryllium alloy casting is obtained;S3, surface cleaning is carried out to the gold beryllium alloy casting obtained in step S2: first, pretreatment is carried out using alkaline solution, then, cleaning is carried out using acidic solution, finally, after cleaning using ultrasonic cleaning machine, drying is carried out, and gold beryllium alloy evaporation material for semiconductor is obtained.The gold beryllium alloy evaporation material for semiconductor prepared by the method of the application has uniform composition, low impurity content, smooth and beautiful surface, and meets the standard requirements of gold beryllium alloy evaporation material.

Description

Technical Field

[0001] The present invention relates to the technical field of nonferrous metal materials, and in particular to a gold-beryllium alloy evaporation material for semiconductors and a preparation method thereof. Background Art

[0002] In the semiconductor industry, to maximize the semiconductor performance of chips, metallization is required on the surface of the semiconductor substrate to achieve ohmic contact. This involves depositing a thin metal film on the semiconductor substrate. This process is accomplished through PVD (physical vapor deposition) or CVD (chemical vapor deposition). Vacuum evaporation coating is a type of PVD. This process heats the raw material in an evaporation vessel, creating a vapor stream that radiates onto the substrate surface, forming a thin film. The raw material used in the coating process is called the evaporating material.

[0003] Because gold-beryllium alloys can form special ohmic contacts with semiconductor substrate materials such as GaP and GaN, they are used in the preparation of semiconductor electrodes. With the rapid development of my country's semiconductor industry in recent years, the demand for gold-beryllium alloy evaporation materials has also greatly increased. In the semiconductor production process, the uniformity and stability of the gold-beryllium alloy determine the performance consistency of the semiconductor electrode. At the same time, the purity of the gold-beryllium alloy will also affect the quality of semiconductor products. Existing gold-beryllium alloy preparation mostly adopts the method of double smelting of gold-beryllium intermediate alloys, that is, the gold-beryllium intermediate alloy is first prepared, and then the intermediate alloy is put into gold liquid for secondary smelting. The smelting process has high requirements for vacuum sealing. The double smelting method is not only cumbersome, but also easily increases the probability of introduction of impurity elements and the instability of performance between batches. Therefore, it is necessary to develop a method for preparing gold-beryllium evaporation materials with simple process and convenient operation. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a gold-beryllium alloy evaporation material for semiconductors and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a gold-beryllium alloy evaporation material for semiconductors comprises the following steps:

[0007] S1. Prepare raw materials Au and Be, the purity of raw material Au is ≥99.99%, and the purity of raw material Be is ≥99.9%;

[0008] S2. Melting the raw materials Au and Be under non-vacuum conditions: Under non-vacuum conditions, the raw material Au is placed in a crucible and heated and melted. After the raw material Au is completely melted, the temperature is kept between 1080-1400°C. After the surface of the molten gold stabilizes, the raw material Be is added to the molten gold. After the temperature is kept for a set time, the obtained gold-beryllium alloy melt is formed to obtain a gold-beryllium alloy casting;

[0009] S3. Cleaning the surface of the gold-beryllium alloy casting obtained in step S2: first, pre-treating with an alkaline solution, then cleaning with an acidic solution, and finally cleaning with an ultrasonic cleaner and drying to obtain a gold-beryllium alloy evaporation material for semiconductors.

[0010] Furthermore, in step S1, a portion of the raw material Au is made into gold foil with a thickness of 0.01-0.1 mm; in step S2, another portion of the raw material Au is first placed in a crucible and heated and smelted to obtain gold liquid; before adding the raw material Be, the raw material Be is first wrapped with gold foil and compacted, and then placed into the gold liquid.

[0011] Furthermore, in step S1, the raw material Be is beryllium beads or beryllium grains, with an equivalent diameter of 1-3 mm.

[0012] Furthermore, in step S2, the crucible is a graphite crucible.

[0013] Furthermore, in step S3, the forming is specifically to pour the gold-beryllium alloy melt into a mold and cool it to form it or to use a continuous casting machine to cast it.

[0014] Furthermore, in step S2, the raw material Be is put into the gold liquid and the holding time is 10-60s.

[0015] Furthermore, in step S3, the mass content of Be element in the gold-beryllium alloy evaporation material for semiconductor is 0.3%-3%, the impurity elements are ≤0.02%, and the balance is Au.

[0016] Furthermore, in step S3, the mass content of Be element in the gold-beryllium alloy evaporation material for semiconductor is 0.3-2.5%, the impurity elements are ≤0.01%, and the balance is Au.

[0017] Furthermore, in step S3, during the pretreatment process, the alkaline solution has a mass concentration of 10-30%, a pretreatment temperature of 50-110° C., and a pretreatment time of 3-10 min; the acidic solution is hydrochloric acid, nitric acid or sulfuric acid solution, with a mass concentration of 10-30%.

[0018] The present invention also provides a gold-beryllium alloy evaporation material for semiconductors prepared by the above preparation method.

[0019] The beneficial effects of the present invention are:

[0020] 1) Compared with vacuum melting, the method of the present invention performs melting under non-vacuum conditions, which greatly lowers the production threshold of beryllium-containing alloys and reduces the difficulty of operation;

[0021] 2) Compared with the currently common secondary smelting method, the present invention adopts a single smelting method, which not only reduces the process flow and improves production efficiency, but also avoids the introduction of other impurities during the smelting process;

[0022] 3) During the smelting process, the method of the present invention uses gold foil to wrap the beryllium beads and uses a secondary charging method for smelting. This solves the problem of beryllium particles floating on the surface of the molten gold due to their low density and difficulty in melting. At the same time, because the beryllium particles sink into the molten gold in a timely manner, the formation of a dense oxide film on the surface of the beryllium particles that prevents them from fully melting is avoided. This allows the beryllium to fully fuse with the molten gold, and the resulting gold-beryllium alloy has a uniform composition.

[0023] 4) In the method of the present invention, the dense beryllium oxide film formed on the surface of the alloy melt in contact with the atmosphere can prevent the melt from further contacting the air, thereby significantly reducing the problems of beryllium volatilization, oxidation, and "hydrogen absorption".

[0024] The gold-beryllium alloy evaporation material for semiconductors prepared by the method of the present invention has uniform composition, low impurity content, smooth and beautiful surface, and meets the standard requirements of gold-beryllium alloy evaporation material. DETAILED DESCRIPTION

[0025] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0026] Example 1

[0027] The standard requirements for the semiconductor gold-beryllium alloy evaporation material to be prepared in this embodiment are: Be element content of 0.5wt%, impurity elements ≤0.01wt%, and the balance being Au element.

[0028] The purity of the raw material Au is 99.99%, and the purity of the raw material Be is 99.9%. In an atmospheric environment, a portion of 99.5g (±0.1g) of pure gold is made into a gold foil with a thickness of 0.05mm. The remaining portion is placed in a graphite crucible and heated using a high-frequency induction heating device. After the pure gold is melted, it is tested with an infrared thermometer and its temperature reaches 1200°C. The heat preservation begins, and the surface of the gold liquid rolls and exhausts. The above-mentioned 0.05mm thick gold foil is used to wrap and compact 0.5g (±0.05g) of beryllium particles (equivalent diameter 2mm). After the surface of the gold liquid stabilizes, the wrapped beryllium particles are placed in the gold liquid. After keeping the temperature for 20 seconds, the resulting gold-beryllium alloy melt is quickly poured into a pre-prepared square flat mold to cool. After the obtained gold-beryllium alloy ingot is cooled to room temperature, it is placed in a 20% NaOH solution at a temperature of 60° C. for pretreatment. After 5 minutes, it is taken out and soaked and cleaned with 10% dilute nitric acid for 10 minutes. After being taken out, it is cleaned with an ultrasonic cleaner and dried to obtain a gold-beryllium alloy evaporation material for semiconductors.

[0029] After ICP testing, the gold-beryllium alloy evaporation material for semiconductors has a Be content of 0.52% and an impurity content of ≤0.01%, which meets the standard requirements for the gold-beryllium alloy evaporation material for semiconductors to be prepared.

[0030] Example 2

[0031] The standard requirements for the semiconductor gold-beryllium alloy evaporation material to be prepared in this embodiment are: Be element content of 1 wt %, impurity elements ≤ 0.01 wt %, and the balance being Au element.

[0032] The purity of the raw material Au is 99.99%, and the purity of the raw material Be is 99.9%. In an atmospheric environment, a portion of 99g (±0.1g) of pure gold is made into a 0.1mm thick gold foil. The remaining portion is placed in a graphite crucible in a molten gold continuous casting furnace and heated. After the pure gold is melted, the continuous casting furnace thermocouple tests the temperature and starts to keep it warm when it reaches 1250°C. At this time, the surface of the molten gold rolls and exhausts. The 0.1mm thick gold foil is used to wrap and compact 1g (±0.1g) of beryllium particles (equivalent diameter 2mm). After the surface of the molten gold stabilizes, the wrapped beryllium particles are placed in the molten gold. After holding the temperature for 50 seconds, the temperature is lowered to 900°C and casting begins. The wire crystallization mold has a specification of 5mm, and a pull-stop process is used (casting speed 5mm / s, pull 5mm stop 0.5s). After the casting is completed, the wire is cut into 10 mm long segments by a cutting machine and placed in a 30% NaOH solution at a temperature of 110°C for pretreatment. After 3 minutes, it is taken out and soaked in 20% dilute sulfuric acid for 10 minutes. After being taken out, it is cleaned with an ultrasonic cleaner and dried to obtain a gold-beryllium alloy evaporation material for semiconductors.

[0033] The diameter of the gold-beryllium alloy evaporation material for semiconductors is 4.8 mm. After ICP testing, the Be content is 0.99% and the impurity content is ≤0.01%, which meets the standard requirements for the gold-beryllium alloy evaporation material for semiconductors to be prepared.

[0034] Those skilled in the art can make various corresponding changes and modifications based on the above technical solutions and concepts, and all of these changes and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a gold-beryllium alloy evaporation material for semiconductors, characterized in that: The steps include: S1. Prepare raw materials Au and Be. The purity of raw material Au should be ≥99.99% and the purity of raw material Be should be ≥99.9%; S2. Melting the raw materials Au and Be under non-vacuum conditions: Place the raw material Au in a crucible and heat and melt it in an atmospheric environment. After the raw material Au is completely melted, keep it warm between 1080-1400°C. After the surface of the molten gold stabilizes, add the raw material Be into the molten gold. After keeping warm for a set time, shape the resulting gold-beryllium alloy melt to obtain a gold-beryllium alloy casting. S3, cleaning the surface of the gold-beryllium alloy casting obtained in step S2: first, pre-treating it with an alkaline solution, then cleaning it with an acidic solution, and finally cleaning it with an ultrasonic cleaner and drying it to obtain a gold-beryllium alloy evaporation material for semiconductors; In step S1, a portion of the raw material Au is made into gold foil with a thickness of 0.01-0.1 mm; in step S2, another portion of the raw material Au is first placed in a crucible and heated and smelted to obtain gold liquid; before adding the raw material Be, the raw material Be is first wrapped with gold foil and compacted, and then placed into the gold liquid; In step S1, the raw material Be is beryllium beads or beryllium grains with an equivalent diameter of 1-3 mm; In step S2, the raw material Be is put into the gold liquid and the holding time is 10-60s.

2. The preparation method according to claim 1, characterized in that In step S2, a graphite crucible is used as the crucible.

3. The preparation method according to claim 1, characterized in that In step S2, the forming is specifically to pour the gold-beryllium alloy melt into a mold and cool it to form it or to use a continuous casting machine to cast it.

4. The preparation method according to claim 1, characterized in that In step S3, the mass content of Be element in the gold-beryllium alloy evaporation material for semiconductor is 0.3%-3%, the impurity elements are ≤0.02%, and the balance is Au.

5. The preparation method according to claim 4, characterized in that In step S3, the mass content of Be element in the gold-beryllium alloy evaporation material for semiconductor is 0.3-2.5%, the impurity elements are ≤0.01%, and the balance is Au.

6. The preparation method according to claim 1, characterized in that In step S3, during the pretreatment process, the alkaline solution has a mass concentration of 10-30%, a pretreatment temperature of 50-110°C, and a pretreatment time of 3-10 minutes; the acidic solution is hydrochloric acid, nitric acid, or sulfuric acid solution, with a mass concentration of 10-30%.

7. A gold-beryllium alloy evaporation material for semiconductors prepared by the preparation method according to any one of claims 1 to 6.