Preparation method of high-density fine-grain easy-to-form W target material

Abstract

The invention discloses a preparation method of a high-density fine-grain easy-to-form W target material, which belongs to the technical field of magnetron sputtering target material manufacturing. The W target material is preformed in a cold pressing mode to obtain a preformed W target blank, and the relative density of the preformed W target blank is 60%-70%; then the preformed W target blank issubjected to hot isostatic presssure sintering densification to obtain a densified W target blank, and the relative density of the densified W target blank ranges from 93% to 96%; and finally, the Wtarget material is subjected to sheath-free secondary hot isostatic pressure sintering densification, the density of the prepared W target material is greater than 99%, the average grain size is lessthan 20 microns, and the yield is greater than 95%. The W target material is low in forming cracking probability, high in yield, simple in process and easy to operate, secondary hot isostatic pressuresintering densification is achieved, the sintering temperature in the hot isostatic pressure process can be reduced, and the tungsten target material with fine grains is obtained.

Description

technical field [0001] The invention belongs to the technical field of magnetron sputtering target manufacture, and in particular relates to a preparation method of a high-density, fine-grained and easy-to-form W target. Background technique [0002] Tungsten target has high melting point (3410°C), high density (19.3g / cm 3 ), high thermal conductivity (165W / (m K)), high strength, low expansion coefficient (4.6×10 -6 mm -1 ), high corrosion resistance and other characteristics, are widely used in the manufacturing process of advanced storage. The tungsten target deposits the W / WN film in the gate metal stack layer to maintain a low gate stack resistivity and prevent the reaction between W and polysilicon. Therefore, high-purity tungsten targets are the key materials for the production of storage devices, and the preparation of high-density, fine-grained high-purity W targets has become a key technology for achieving excellent coatings. Among them, due to the characteristi...

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Problems solved by technology

[0004] (1) After hot pressing (HP) of tungsten powder, hot isostatic pressing (HIP) without sheath is carried out. The tungsten powder is pressed by hot pressing. In order to increase the density, high temperature is required to make up for the short plate of low hot pressing pressure. High temperature It will promote the grain growth in the tungsten target, which is not conducive to the acquisition of fine-grained tungsten targets;

[0005] (2) Preforming of tungsten powder (which can be carried out by hot pressing, cold isostatic pressing (CIP), and hot isostatic pressing) reaches a density of 70% to 90% and then carries out hot isostatic pressing and sintering with a jacket, but the preparation In the process, niobium and tantalum materials need to be used for sheathing, which are expensive and difficult to process, seal and weld, and the process is difficult to implement and the yield rate is low;

[0006] (3) Pressureless sintering in hydrogen atmosphere after cold isostatic pressing of tungsten powder, and finally hot isostatic pressing without jacket, but the temperature required for pressureless sintering in hydrogen atmosphere during the preparation process is high (>1900°C), It is easy to cause coarse grains inside the W target, which will affect the subsequent magnetron sputtering coating process;

[0007] (4) After cold isostatic pressing of tungsten powder, pressureless sintering in hydrogen atmosphere is carried out, and finally hot rolling is carried out to increase the density, but the hot rolling process is easy to produce banded structure and preferred orientation, resulting in coarse product structure;

[0008] (5) The spark plasma sintering (SPS) process of tungsten powder is only suitable for sample preparation in the laboratory stage, and cannot be applied to the preparation of large-size tungsten target blanks in industrial production

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