The manufacture method of the block raw material of a kind of alumina single crystal
Technical field
The invention belongs to the semi-conducting material production field, relate to the wherein initial feed of alumina single crystal (claiming sapphire, white stone again) finished product, be specifically related to the manufacture method of the block raw material of a kind of alumina single crystal.
Background technology
At present, the substrate material of semiconductor LED diode (claiming led chip again) has silicon (Si), carborundum (SiC), aluminium oxide (Al
2O
3)) three kinds.Because the alumina single crystal chemical stability is good, it is ripe relatively not absorb visible light, moderate cost, manufacturing technology, so be the main product on the market.
In theory, alumina powder can be directly used in the manufacturing alumina single crystal; But to vacuumize usually in the single crystal growing furnace growing single-crystal process and charge into inert protective gas, and fly upward along with gas flow can cause powder, cause gas inlet and outlet to stop up, cause equipment fault with dangerous.So, directly unworkable in practice with powder body material.At present, the preparation alumina single crystal, mostly adopting the sintered alumina blocks is raw material.
And the conventional preparation technology of sintered alumina blocks material is: to become proportion at thousands of degree high temperature sinterings after moulding be 3.0-3.3g/cm with alumina powder jointed
3About bulk, as the raw material of making alumina single crystal.Most ofly in this traditional handicraft adopt dry-pressing formed method, it at first will add the organic additive of assistant formation in alumina powder, as lubricant, binding agent and surfactant etc., in dry press by the particular manufacturing craft moulding; Thereafter need pass through the low temperature binder removal, high temperature sintering can be prepared the alumina block material.This technology manufacturing time is long, and energy consumption is big, thereby the cost height.
In addition, on the method for making block material, dry press adopts unidirectional pressurization or two-way pressurization also can mold block material by particular manufacturing craft, but because particle moves and particle is rearranged between the particle, produce frictional force between particle and the mold wall in pressing process, can hinder the transmission of pressure, the pressure that base substrate is subjected to away from the pressure surface is just little from adding, and whole blank density is inhomogeneous, should not directly be used as the alumina single crystal manufacturing, need to form bulk through thousands of degree high temperature sinterings and expect.
Summary of the invention
The object of the present invention is to provide the manufacture method of the block raw material of a kind of alumina single crystal, this method has technology and makes simply, with low cost, and does not need sintering, advantage that efficient is high.
The technical scheme that the present invention provides to achieve these goals comprises,
The manufacture method of the block raw material of a kind of alumina single crystal, its concrete steps are as follows:
(1) mould preparation: get rubber or macromolecule soft package material is made container;
(2) select for use particle diameter at 0.1 micron-1000 microns, purity is that 99.999% alumina powder is raw material, and alumina powder is put into the soft package container of material, the strict sealing of vessel port;
(3) the soft package container of material that alumina powder is housed with good seal in the previous step places cold isostatic press (this cold isostatic press transmits pressure by liquid medium);
(4) to the soft package container of material pressurization of alumina powder is housed, the pressurization scope is 10-800MPa to cold isostatic press by liquid medium; Be 5-60 minute pressing time;
(5) after pressure release reached normal pressure, the material that takes out in the container namely obtained the block material of raw material, puts into alpha-alumina crystals growth furnace crucible;
Be pressurised into the bulk material of 500 MPa preparation, resistance to compression and antioxygenic property just can meet the demands substantially.
Adopt little mould can obtain the bulk material of 20-80mm.
The block raw material that relates among the present invention in full refers to put into the single crystal growing furnace crucible, still not have to heat up to melt aluminium oxide with the bulk of crystal growth, and this bulk raw material is as the raw material of production alumina single crystal.
The purity of this bulk raw material is 99.999%, and resistance to compression parameter that should the bulk raw material is 0.1-50 MPa; After isostatic cool pressing is prepared into bulk, put into alpha-alumina crystals growth furnace crucible.
Static pressure method such as had to obtain the record of 300-400kg graphite crucible in the prior art.Because the isostatic cool pressing technical development is rapid, the weight and volume of product develops to the maximization direction, obtains the alumina block material of 20-80mm size, is easy to realize.
After the shelf life that relates among the present invention referred to storage through certain hour, the alumina block material was oxidized or accounted for more than 97% of weight ratio of total amount by the amount of contaminating impurity, and this elapsed time is exactly the shelf life.
The piece material that sintering is crossed when using (or the cutting material that cuts down melt down again) need carry out the chemical solvent washing, in order to remove oxide layer and pollute impurity, but this washing process also exist introduce new impurity may with danger; And the product of the present invention's preparation, well behaved block of material of the filling that obtains after the isostatic cool pressing running parameter is more than or equal to 150MPa almost can carry out chemical washing and impurity elimination again and handle.
If expect harder bulk product, after the isostatic cool pressing running parameter is more than or equal to 1000MPa, since very harsh to the requirement of equal pressing equipment, generally do not adopt.
Since to obtain the resistance to compression parameter more than or equal to the piece material of 70MPa, very harsh to the requirement of isostatic cool pressing equipment or other facilities, generally do not adopt yet.
Compared with prior art, the invention has the advantages that to have technology and make simply, with low cost, and do not need sintering, characteristics that efficient is high.
The specific embodiment
Embodiment 1, with purity be 99.999%, particle diameter is 0.1 micron alumina powder, when selecting to be pressurised into 100MPa; Be 30 minutes pressing time, be the piece material of 20mm through cold isostatic compaction after, put into the stove crucible of crystal growth, be used for the alumina single crystal growth, Here it is a kind ofly makes raw material prepares alumina single crystal in single crystal growing furnace application process with the alumina block material.
Embodiment 2, with purity be 99.999%, particle diameter is 0.5 micron alumina powder, when selecting to be pressurised into 120MPa; Be 40 minutes pressing time, be the piece material of 30mm through cold isostatic compaction after, put into the stove of crystal growth, be used for the alumina single crystal growth, Here it is a kind ofly makes raw material prepares alumina single crystal in single crystal growing furnace application process with the alumina block material.
Embodiment 3, with purity be 99.999%, particle diameter is 0.8 micron alumina powder, when selecting to be pressurised into 130MPa; Be 50 minutes pressing time, be the piece material of 40mm through cold isostatic compaction after, put into the stove of crystal growth, be used for the alumina single crystal growth, Here it is a kind ofly makes raw material prepares alumina single crystal in single crystal growing furnace application process with the alumina block material.
Embodiment 4, with purity be 99.999%, particle diameter is 1 micron alumina powder, when selecting to be pressurised into 140MPa; Be 55 minutes pressing time, after being the piece material of 50mm through cold isostatic compaction, become the piece material of 50mm through isostatic cool pressing after, put into the stove of crystal growth, be used for the alumina single crystal growth, Here it is a kind ofly makes raw material prepares alumina single crystal in single crystal growing furnace application process with the alumina block material.
Embodiment 5, with purity be 99.999%, particle diameter be chosen as 0.1 micron-1000 little between in alumina powder, when selecting to be pressurised into 150MPa; Be 60 minutes pressing time, be the piece material of 60-80mm through cold isostatic compaction after,, put into the stove of crystal growth, be used for the alumina single crystal growth, Here it is makes raw material prepares alumina single crystal in single crystal growing furnace application process with the alumina block material.
The alumina powder that employing the present invention relates to is prepared into the piece material through isostatic cool pressing, can significantly improve the various negative effects of the oxidized generation of alumina powder.The effect of improving is mainly reflected in alumina powder and can deposits after isostatic cool pressing becomes bulk more than half a year, can not influence the quality of backing material because of the generation of oxide-film.
If directly use alumina powder, because powder flies upward and easy oxidized reason, in single crystal growing furnace, be difficult to direct application.
Alumina powder provided by the invention is prepared into the piece material through isostatic cool pressing, though its density is lower than 3.3 grams/cubic centimetre slightly, but it has just had good density when the resistance to compression parameter equals 1Mpa, its inner structure is closely substantially, be enough to secluding air to interior oxidation, and the good raw material block material surface of compressive property is oxidized on a small quantity, and the backing material quality of final acquisition is not had tangible negative effect.
In order to investigate alumina powder of the present invention is processed into piece material raw material through isostatic cool pressing applicable cases, the present invention did following experiment: alumina powder of the present invention is pressed into piece material (getting material amount<1 0kg) through isostatic cool pressing puts into after single crystal growing furnace finishes the crystal growth that reaches week age, its performance is measured in the directed section of the alumina monocrystal that takes out back, all can satisfy the quality requirement of LED backing material, the alumina powder that relates in the technology of such alumina block material and the preamble needs the alumina block material technology of low temperature binder removal high temperature sintering to compare, and cost advantage is obvious.
Because the present invention relates to multinomial technology, in order to understand conveniently, it is as follows that we do relevant note especially:
Whether isostatic pressing technology is according to there being heater to be divided into two kinds of isostatic cool pressing and high temperature insostatic pressing (HIP)s in the equipment.
Isostatic cool pressing refers at normal temperatures material be applied each makes a kind of technology from its moulding to the pressure that equates.The characteristics of isostatic cool pressing technology maximum are to have each to uniformity by isostatic pressing machine by liquid or gas institute applied pressure, and the various overall performances from outward appearance to inner essence of resulting alumina block material are all very even, and particularly compressive property is good.
High temperature insostatic pressing (HIP) is on the basis of isostatic cool pressing technology, makes material forming by increasing heating apparatus heating and waiting to the method for pressurizeing.Owing to increased heating process, its effect is better than isostatic cool pressing technology; But its requirement to auxiliary equipment is very high, and the jacket problem that especially solves the powder body material parcel under the condition of high temperature is very difficult.When temperature was spent above 1300, prior art can't solve the sheath material problem both at home and abroad at present, so seldom use.
Be generally the piece material that obtains being easy to into piece, can add the organic bond of proper ratio, but add the negative effect that a certain proportion of organic bond can bring the impurity aspect for the semiconductor grade substrate slice of preparation, so finally also need to adopt suitable method to remove these adhesives.Can be in subsequent processes break away from (be convenient to load into crucible) the raw material block material that the present invention relates to because the volatilization of being heated is final owing to be fit to the organic bond of the trace of semiconductor applications, so do not influence the purity of this backing material.
Usually adopt the alumina block material of high temperature sintering to make the alumina single crystal raw material, for despumation, carry out pickling.Well behaved block of material of filling provided by the invention then solved the harsh difficult problem that requires in storage condition aspect, places the air condition of storage of normal temperature, normal pressure, and the shelf life is influenced hardly; Also reduced and carried out the chemical solvent washing deoxidation surperficial to it or removing chemical solvent consumption and the time that consumes in the process of polluting impurity.