CN108517497A - A kind of method that centrifugal forming prepares NiPt alloy target - Google Patents

Abstract

The invention discloses a kind of methods that centrifugal forming prepares NiPt alloy target, it is related to preparing sheet member NiPt alloy target using centrifugal forming casting process, implement damaging influence caused by stress processing to avoid to ingot casting, simplify production process, ensure product material purity, greatly improves finished product rate.When NiPt alloy composition proportion enters the section of 40 90wt.%Pt, ordering transition can occur for system, and the stress processing performance of alloy can be weakened significantly by being formed by ordered structure.It is cast by using rotary heating platform and specially designed mold, make ingot casting shape almost shape of product, it is follow-up to can reach final size by simple machining, qualified products are made, high scrappage when successfully solving the problems, such as the ingredient section product to be processed using traditional stress processing method.

Description

A kind of method that centrifugal forming prepares NiPt alloy target

Technical field

The present invention be directed to the special preparation methods that 40-90wt.%Pt ingredients section NiPt alloy target is proposed, to keep away Exempt to process caused high rejection rate using stress, simplifies production technology, ensure purity, improve the quality and finished product of target Rate.

Background technology

Currently, semiconductor integrated circuit (IC) industry enters after 65nm and 45nm technology nodes, due to line width effect Limitation, the NiPt- silicides contact institute that Titanium silicide, cobalt silicide (90nm or more) have been prepared by nickel and nickel alloy target Substitution, becomes most common silicide；Have using NiPt alloy as nickel silicide prepared by the sputtering technology of target wireless Wide benefit and bridging phenomenon, film resistor and leakage current is small, process annealing can be such that less silicon atom migrates are residual in film The advantages that residue stress is small is applied to Schottky diode (SBD), complementary mos device (CMOS), field effect Answer the fields such as transistor (FET) and integrated circuit.Addition Pt, which can be reduced or eliminated, during forming NiSi occupies defect, Ni-5at.%Pt has been applied successfully to 65nm technologies, and Ni-10at.%Pt is applied to 45nm technologies, with semiconductor devices line Wide is further reduced, then needs the NiPt of higher Pt contents to prepare Ni (Pt) Si and contact film；Meanwhile Pt is as non magnetic Element, in target the raising of Pt contents be conducive to the raising of its magnetic spectroscopy susceptibility (PTF), increase sputtering yield.It is public in document [1-7] Opened a large amount of preparation methods of NiPt targets, involved by Ni, Pt element proportioning covered entire 1-99wt.% ranges, close Also all it is that traditional cool thermoplastic becomes shaped like rolling and forging in its processing method.However the present inventor is in practical NiPt alloy target It is found in the manufacture course of work of material, when the content of Pt is in (40-90wt.%) in a certain particular range, alloy Processability can be deteriorated and even disappear completely suddenly, as long as the strain for applying very little will make entire ingot blank discrepitate even entirety Similar situation is then encountered outside this composition range in avalanche；This phenomenon is different from the fracture of hard brittle matrix, because right Ingot blank carries out finding that it has good plasticity and low-down hardness (this and nickel in local a small range when micro-hardness testing The fundamental property of platinum coincide).Further investigation shows that bianry alloy thermodynamical equilibrium phasor is shown, when the content of Pt is located at~40- When within the scope of 90wt.%, ingredient separation occurs for system under middle low temperature, generates Ni₃Two kinds of ordered structures of Pt and NiPt；Practical feelings It was found that these ordered phases can be germinated to habit in grain boundaries and are distributed along crystal boundary in the form of fine particle in condition, this Kind state tempestuously weakens the combination between crystal boundary and crystal boundary；When ingot blank is by smaller stress from some direction, The plastic deformation of matrix even has little time to start (or not up to yield stress), and grain boundaries will be sliped off and be cracked quickly, Crackle runs through rapidly entire ingot blank along the crystal boundary Quick Extended of reduction.Nickel alloy is easily oxidized, and when system aoxidizes When, grain boundaries are also the places of preferential oxidation, and at this moment oxide further weakens the combination between crystal boundary along crystal boundary distribution, this It also explains in real work and ingot blank anneal so that the reason of its processability further deteriorates under air.It is used now NiPt target products be thin sheet form part, thickness is differed according to different demands in about 2-8mm, and width dimensions are up to About 600mm, such shape Regular casting methods cannot achieve, and in actual production work, in above-mentioned document The manufacturing process such as the conventional rolling or forging that refer to are to being located at the alloy product ingot blank in (40-90wt.%Pt) composition range When being processed, high rejection rate is up to 95% or more；Simultaneously as grain boundaries easy to produce crackle, and fresh cracks are also It is aoxidized first and by the position that gaseous impurity is stained, causes the internal flaw of target product to be increased sharply, purity substantially reduces.

The problem of for NiPt target products within the scope of mentioned component, the present invention devise a kind of special thin Plate casting method makes every effort to reduce stress process to the greatest extent, reduces product rejection rate, avoid the heat treatment for being easy to bring oxidation Process improves purity.

Invention content

The present invention for the NiPt alloy of (ordered structure limited proportionality) in (40-90wt.%Pt) composition range it is unstressed plus The characteristics of work, and it is an object of the present invention to provide a kind of special casting method, relates generally to the design of casting die and casting method, makes Ingot casting reduces stress process closer to final products shape, and heat treatment is avoided to bring re-oxidation, improves the production of nickel platinum target Product yield rate.

The typical composition of nickel platinum alloy target according to the present invention is~40-90wt.%Pt, in this section, alloy Ordering pransition will occur in system, and the stress processing performance of alloy can significantly be weakened by being formed by ordered structure, so passing through Fusion-casting process is controlled, ingehious design casting die and centrifugal forming casting method so that cast shape is close to product shape Shape reduces stress manufacturing procedure to the greatest extent and for its matched heat-treatment of annealing process, simplifies production technology, substantially increase Finished product rate and purity, details are provided below：

Using nickel and platinum raw material, dispensing, composition range 40-90wt.%Pt are carried out according to product demand；

Using vacuum intermediate-frequency sense melt furnace, furnace chamber is first evacuated to high vacuum, then backfilled with argon, then be evacuated to high vacuum, held Melting is carried out under protection of argon gas after the multiple ar purging of row.

Based on the characteristic of alloy in the composition range, see from bianry alloy thermodynamic equilibrium state figure, although being in Ordering transition section, but alloy has very narrow crystallization range within this range, i.e., between its liquidus curve and solidus Temperature difference very little, two lines, which overlap, especially at~55wt%Pt becomes lowest total of the melting point, this feature imparts alloy The excellent mobile performance under liquid phase state becomes the theoretical foundation that the sheet member casting technique that the present invention is implemented is realized.

Casting method designed by the present invention is centrifugal molding process, including heatable rotating platform and special graphite Casting die includes the design of running channel and insulated feeder.

It is circle to heat rotating platform, and diameter can be adjusted according to demand, and material is to be not susceptible to thermal deformation Metal (heat-resistance stainless steel but unlimited) or graphite (unlimited) etc., can in vacuum and protective atmosphere environment temperature in use to 800 DEG C, It is required that surfacing, thickness is to ensure that rigidity and heat transfer efficiency consider formulation；Heater is arranged in platform lower, and electricity can be used Forms, the heating power such as stove silk or heating rod (unlimited) are adjusted according to demand, can be used single group or multigroup form there is no harm in Platform is hindered to rotate to be purport, heating power supply is set to outside furnace body, can be arranged as required to or be not provided with temperature measuring equipment；Motor and tune Fast mechanism is set to outside furnace body, is sealed using vacuum operating bearing between furnace shell and power arm, and platform rotating speed is 0-300r/ Min is adjustable.

Casting die is made of three high graphite (high-purity, high-strength, high density), is upper and lower parting mold.Lower die is circle Plate-like, thickness consider setting to take into account heat transfer efficiency and heat insulating ability, and bottom is smooth to be close to rotating platform, and diameter is according to requiring to set Fixed, it is 10-15mm (unlimited) that, which there are Pan Bi, the high wall thickness of wall in edge, and interior to survey there are 1-2mm (unlimited) chamfering, circle centre position digs arc-shaped Holding hole, diameter 30-50mm, depth 5-10mm increase heat preservation and the mold-filling capacity of mold；Upper mold is consistent with lower die shape, Two-half die is designed as to facilitate die sinking, closing can be assemblied in be whole on the inside of lower die, and fit-up gap to be without shaking and no leakage Purport is highly adjusted with product thickness demand, and inner surface is smooth, circle centre position digging back taper (up-small and down-big) cast gate, under face Mould keep hole, osculum diameter 35-45mm (unlimited), big mouth diameter be more than osculum, at (osculum) suitable for reading there are boss so as to pour Road is assembled, and upper mold includes the venthole (through-hole) that side wall makes diameter 0.3-0.5mm, and venthole is along center in fan-shaped point Cloth, the distance between Kong Yukong are to spread all over entire upper mold no more than 10mm；Running channel and riser are three high graphite integral manufacturings, if Two-half die is calculated as to facilitate die sinking, running channel that can be assembled with upper mold boss, internal diameter is identical as upper mold osculum, running channel length 30- 40mm (unlimited), upper end are directly connected to riser, and riser is taper, and osculum is both running channel internal diameter, the big a diameter of osculum diameter of mouth Twice (unlimited), bores a height of 30mm (unlimited), and the upper ends great Kou connect straight wall, height 30-40mm (unlimited), running channel and riser wall thickness For 10-15mm (unlimited), fastened from outside using particular jig.

Mold includes that running channel and riser inner surface are polished or spray releasing agent processing according to conveniently stripped principle, is pressed Mold is fixed on rotating platform after assembling using special fixtures by design, needs to wrap in outside when in use at riser and running channel Wrap up in thermal insulation material (such as zirconium oxide cotton but unlimited).Mold is heated simultaneously during alloy melting, reaches institute It needs temperature, when casting, so that mold is rotated, set to required rotating speed, alloy liquid stream is poured into running channel with certain rate stabilization, Finally ensure to pour at riser full, completion founding.

Beneficial effects of the present invention are：For the nothing in actual production in special component section present in NiPt alloy target Method carries out the problem of stress processing, according to the characteristic of the alloy, devises a whole set of sheet member centrifugal forming casting technique, makes casting Part shape almost shape of product, it is ingenious to avoid stress processing and required heat treatment procedure, it ensure that product purity, significantly Improve finished product rate.

Specific implementation mode

Below by embodiment, the present invention will be further described, but not limited to the examples.

Embodiment 1

The NiPt target products of the xxx trades mark are produced, thickness 2.5-3mm, circular strip is cambered, diameter 450mm, composition proportion For Ni-60wt.%Pt.It uses nickel of the purity not less than 99.95% and platinum to stock up for raw material, is incuded using vacuum intermediate-frequency molten Stove, with melting under protection of argon gas after the multiple prepurging of argon gas；It using diameter 450mm*4mm molds, assembles, adds before casting as required Heat is arranged rotating speed 120-150r/min, is wrapped up running channel and riser using zirconium oxide cotton, by melt temperature to 450-500 DEG C Degree does not stop at the uniform velocity after improving about 100 DEG C and pours into mold, until riser pours completely, constantly heating and rotation, waits for half an hour therebetween Stop heating and rotation afterwards.Be fully cooled rear blow-on and take out mold, Filling Processes of Castings is good, and shape is complete, cut after riser by Plane milling reaches product required thickness, then forms cambered surface through rotary press modelling, and final products surface quality is good, flawless, through visiting Wound test is internal without hole is mingled with, and carries out chemical composition and impurity content analysis, as a result meets the requirements, PTF detections are qualified, reach Shipment standard is primary qualified.

Embodiment 2

Produce the NiPt target products of the xx trades mark, thickness 6.0-6.5mm, rectangular, size 400-420mm*120- 125mm, composition proportion Ni-76wt.%Pt.Using smelting technology in the same manner as in Example 1, diameter 450mm*7mm is used Mold, casting process and mold assembly are same as Example 1.Cast shape is complete, and riser cutting is carried out after taking-up, uses shear Machine uses facing cut and plane milling to reach final products size after cutting out to general shape, and final products surface quality is good, and nothing is split As a result line meets the requirements, PTF detections are closed through without hole is mingled with, carrying out chemical composition and impurity content analysis inside test of flaw detection Lattice reach shipment standard, primary qualified.

Bibliography：

[1] Chinese patent CN101353732A

[2] Chinese patent CN104018120B

[3] Chinese patent CN104018128A

[4] Chinese patent CN104178739A

[5] Chinese patent CN104726829A

[6] Chinese patent CN105986138A

[7] European patent EP 2025768A1

Claims (7)

1. a kind of method preparing NiPt alloy target, involved ingredient section is 40-90wt.%Pt, it is characterised in that：It adopts With casting die and casting process so that cast shape is shape of product.

2. the method for preparing NiPt alloy target according to claim 1, it is characterised in that：Involved casting process be from Heart moulding process.

3. the method for preparing NiPt alloy target according to claim 2, it is characterized in that：The centrifugal molding process uses can For the rotating platform of heating as the pedestal for placing mold, heating temperature is adjustable, and highest is not less than 600 DEG C, and rotating speed is adjustable, and highest is not Less than 300r/min.

4. the method for preparing NiPt alloy target according to claim 2, it is characterized in that：The centrifugal molding process uses three High graphite makes discoid mold and running channel and riser, and mold is upper and lower two halves make-up, and lower die is big, and circle centre position setting is kept Hole；Casting thickness is controlled by upper mold, and upper mold uses split cavity, and entire upper mold includes that side wall beats diameter 0.3-0.5mm ventholes, hole Spacing is no more than 10mm；Running channel and riser use split cavity.

5. the method for preparing NiPt alloy target according to claim 3, it is characterized in that：Mould inner surface may include but unlimited Releasing agent processing is polished or sprayed so that ingot casting demoulds, first heats mold before casting, using including but unlimited heat preservation Cotton etc. wraps up running channel and riser, and rotary speed is set according to casting size, is finally poured with stablizing not disconnection state Casting pours riser completely, keep mold heating and rotate 10 minutes or more.

6. the method for preparing NiPt alloy target according to claim 4, it is characterized in that：Final products are compared in casting thickness setting Thickness thickness about 0.5-1mm, mould inner surface may include but it is unlimited be polished or spray releasing agent processing in favor of ingot casting demould, First mold is heated before casting, using including but unlimited heat-preservation cotton etc. wraps up running channel and riser being set according to casting size Determine rotary speed, finally cast with stablizing not disconnection state, riser is poured it is full, keep mold heating and rotation 10 minutes with On.

7. a kind of method preparing NiPt alloy target, involved ingredient section is 40-90wt.%Pt, it is characterised in that packet Containing following processing step：

Nickel of the purity not less than 99.95% and platinum is used to stock up for raw material, composition proportion Ni-60wt.%Pt, using true Aerial frequency sense melt furnace, with melting under protection of argon gas after the multiple prepurging of argon gas；Using diameter 450mm*4mm molds, as required Assembly is heated to 450-500 DEG C before casting, rotating speed 120-150r/min is arranged, and is carried out running channel and riser using zirconium oxide cotton Package does not stop at the uniform velocity after melt temperature is improved about 100 DEG C and pours into mold, until riser pours full, constantly heating and rotation therebetween Turn, stop heating and rotation after waiting for half an hour, is fully cooled rear blow-on and takes out mold, Filling Processes of Castings is good, and shape is complete, cuts It cuts and reaches product required thickness by plane milling after riser, then cambered surface is formed through rotary press modelling, final products surface quality is good, As a result flawless meets the requirements, PTF is examined through without hole is mingled with, carrying out chemical composition and impurity content analysis inside test of flaw detection It is qualified to survey, and reaches shipment standard, and primary qualified, the NiPt target products of production, thickness 2.5-3mm, circular strip is cambered, diameter 450mm。