CN100400721C

CN100400721C - Process for producing wafer

Info

Publication number: CN100400721C
Application number: CNB200480023198XA
Authority: CN
Inventors: 小林武史
Original assignee: Shin Etsu Handotai Co Ltd
Current assignee: Shin Etsu Handotai Co Ltd
Priority date: 2003-08-12
Filing date: 2004-08-04
Publication date: 2008-07-09
Anticipated expiration: 2024-08-04
Also published as: JP2005060168A; CN1836062A

Abstract

A process for producing a wafer, comprising at least the BMD formation step of subjecting a silicon single crystal having the form of an ingot to heat treatment to thereby form bulk microdefects (BMD) in the interior thereof, and the wafer machining step of machining the ingot furnished with the bulk microdefects (BMD) into a wafer. In this process for producing a wafer, the heat treatment for imparting IG capability in the wafer production can be shortened to thereby enable mass production of wafers of high IG capability. The process can further comprise the wafer heat treatment step of performing heat treatment of wafers after machining and the epitaxial growth step of forming an epitaxial layer on each of the wafers with the result that the productivity of, excelling in gettering effect, anneal wafers and epitaxial wafers can be enhanced.

Description

The manufacture method of wafer

Technical field

The present invention relates to the manufacture method of wafer, particularly a kind of can the low-cost method of making wafer, this wafer is (air-breathing in the body in order to give IG; Intrinsic Gettering) ability and generate aerobic precipitate and inner tiny flaw BMD (Bulk Micro Defect).

The invention still further relates to a kind of manufacture method of the wafer of annealing, the manufacture method of particularly relevant a kind of wafer of annealing is in order to form the DZ (nondefective zone of nondefective zone on the surface; Denuded Zone) layer, and make oxygen generate the thermal treatment of oxygen precipitate and inner tiny flaw BMD toward the thermal treatment of outside diffusion, in order to give the IG ability.

And, the invention still further relates to a kind of manufacture method of Jingjing of heap of stone circle, particularly relevant for a kind of can efficient make well have good gettering efficiency, the manufacture method of Jingjing circle of heap of stone that the epitaxial layer defective is few.

Background technology

As the silicon single crystal wafer of semiconductor integrated circuit module board, mainly by Czochralski method (Czochralski method; The CZ method) makes.So-called CZ method is meant in quartz crucible, and the kind crystallization of silicon single crystal is immersed in the silicon melt that forms with the high-temperature fusion more than 1420 ℃, and the limit makes quartz crucible rotate the limit pull-up crystal seed method of cultivating columned silicon single-crystal at leisure.At this moment, the quartz crucible melt surface that contacts with silicon melt, oxygen dissolves in the melted silicon, is taken in the crystallization in the cultivation.This Sauerstoffatom reaches in crystallization is cultivated and condenses in cooling, becomes oxygen and separates out nuclear.Therefore, if 700 ℃ to 1050 ℃ temperature range to Silicon Wafer (crystallization of directly taking to cultivate) when applying thermal treatment from this, this oxygen is separated out nuclear and can be grown up and form oxygen precipitate and BMD.This oxygen precipitate has the so-called useful task of catching the metallic pollution that is produced in long-pending circuit module manufacturing processed (assembly step) of serving as.In the so-called body air-breathing (IG).

The assembly step is the heavy metal contamination of representative because have with Fe, Ni, Cu at pyritous heat treatment step etc., these heavy metal contaminations are if when forming defective and level (electricallevel) near crystal column surface, the characteristic meeting variation of assembly, be necessary to be that various IG of employing or various EG are (air-breathing in the non-body from removing this heavy metal contamination near the crystal column surface in the past; Extrinsic Gettering) air-breathing method.Particularly assembly step from now on can be known and know and will advance towards the low temperatureization of Gao Jitiization and use high energy ion implantation step that at this moment, because step low temperatureization, prediction will become difficulty in the formation of BMD midway of assembly step.Thereby, in low temperature step,, be not easy to obtain sufficient IG effect with when high-temperature step compares.Again, even assembly step low temperatureization also can't be avoided the metallic pollution that produced in high energy ion implantation etc., air-breathing technology is necessary to consider.For the generation that suppresses to slide, be preferably and have highdensity BMD again.

The formation of common BMD is silicon single crystal have been carried out wafer processing back wafer is heat-treated.For example known have thermal treatments such as DZ-IG thermal treatment.It is by to carry out the pyroprocessing of about 1100 ℃ to 1200 ℃ of temperature through the finished mirror-like wafer of wafer, make near the oxygen of crystal column surface toward outside diffusion, reduce oxygen between the grid of the nuclear that becomes tiny flaw, form flawless DZ (Denuded Zone) layer in the assembly active zone.Subsequently, by 600 ℃ to 900 ℃ low-temperature heat treatment, carry out so-called two sections thermal treatments of high temperature+low temperature that in wafer table body, form BMD.Again, also have and at first carry out subzero treatment and form BMD fully, form the DZ layer on the wafer top layer by high-temperature heat treatment subsequently.Give the wafer that DZ layer or IG ability form by heat-treating, be called annealing wafer etc. at this kind wafer state.

On the other hand, cultivate the silicon single crystal form as described above, contain the aerobic impurity usually, when this kind state directly is used in the assembly manufacturing step, in step, has oversaturated oxygen and separate out by the CZ method.The oxygen precipitate can produce the distortion because of volumetric expansion, causes producing the situation of secondary transposition or lamination defective etc.Because these oxygen precipitates and secondary defect thereof can have influence on the characteristic of semiconductor subassembly gravely, if when this kind defective is arranged, have situations such as to cause that leakage current increases, oxide film is withstand voltage bad at crystal column surface and assembly active coating.

Again, be accompanied by Gao Jitiization, the miniaturization of assembly, growth (Grown-in) defective that was imported when in the past not being regarded as the CZ method silicon wafer single crystal pull-up of problem, because can make the remarkable variation of oxide film voltage endurance, so near the crystallinity the silicon single crystal the substrate well whether widely reliability of left and right sides assembly and productive rate.

Its countermeasure has the thermal treatment of applying to eliminate the technology of the defective of crystal column surface.(for example disclose a kind of wafer heat-treating methods, opening clear 60-231365 communique, spy with reference to the Japanese Patent spy opens clear 61-193456 number, spy and opens clear 61-193458 communique), be disclosed in and make wafer substrate under the hydrogen environment or hydrogen contains in the environment, with 5 minutes from 950 ℃ of temperature that are heated to 1200 ℃, promote oxygen to spread the method that forms the DZ layer toward the outside.

Again, in recent years, the nitrogen that mixes is also arranged in wafer (silicon wafer ingot), can make COP (CrystalOriginated Particle; The particulate of crystallization cause) etc. result from that the crystalline defective is eliminated easily and can easily obtain the method for oxygen precipitate.By this, can make annealing wafer effectively with wide nondefective zone.

And then known have a kind of crystallization, though be by the atom emptying aperture superfluous do not have that crystalline growth imports defective (crystal defects of COP etc.) though the district, and grid between Siliciumatom is superfluous does not have crystalline growth importing defect area and constituted.It is waited to control by crystalline pull-up speed and obtains, and can almost not had the wafer of crystal defect.Have though this kind atom emptying aperture is superfluous that crystalline growth imports defective (crystal defects of COP etc.) though the district, and grid between Siliciumatom superfluous but not having crystalline growth imports crystallization that defect area constitutes, be called quasi-full crystallization (Nearly perfect crystal), the situation that is called NPC is below arranged.The annealing wafer (for example, opening flat 11-199387 communique) that uses this kind crystallization to make effectively to have wide surperficial nondefective zone (DZ layer) with reference to the spy.Using the Jingjing circle of heap of stone of growing up on this kind crystalline wafer also can make high-quality wafer effectively again.

But, for example, be called the heat treated annealing of DZ-IG as above-mentioned, need carry out 2 sections thermal treatment because on wafer, forming the various objectives of DZ layer and formation BMD layer, so need the long duration.When particularly forming BMD to high-density, must heat-treat with low temperature and considerable time.

When being processed into the wafer state thermal treatment of Silicon Wafer, can use vertical heat processing apparatus 30 as shown in Figure 6, by the well heater 32 in the treatment chamber 31, heat the wafer W that is installed on the brilliant boat 40 of thermal treatment.Again, the installation of wafer is to use the brilliant boat 40 of thermal treatment shown in Figure 7, wafer W is remained in the wafer mounting portion 43 of groove shape, and this wafer mounting portion 43 is on the plural pillar 42 that is arranged on linking part 42 bindings.But the sheet number of the wafer that can install is limited to about 100 at the most.Therefore, in order to produce the annealing wafer in large quantities, must prepare many thermal treatment units or shorten annealing time.

But, along with the heavy caliberization of wafer, carry out this kind heat-treating apparatus and also maximize, and the brilliant boat of employed thermal treatment also maximizes, on equipment, very price apparatus must be arranged.Thereby desire has its limit when importing many devices on cost, and it is important using the thermal treatment unit of good efficiencies.

On the other hand, also use many Jingjings of heap of stone circles at present, this Jingjing circle of heap of stone is that the unijunction crystal layer of growing up from the teeth outwards forms.Jingjing circle of heap of stone has the good advantage of crystallinity of near surface.Again, because by the building crystal to grow technology, be easier to inner form precipitous impurity concentration gradient at wafer, form low concentration layer in the inside of high concentration layer, Jingjing circle of heap of stone is a necessary wafer when making bipolar transistor or Schottky gesture and changing diode (Schottky barrier diode).The formation of this kind epitaxial layer is to carry out with the high-temperature step more than 1000 ℃.

In this alleged high-temperature step more than 1000 ℃, the preceding pre-treatment of being carried out of building crystal to grow itself and building crystal to grow is arranged again.The building crystal to grow of silicon crystalline membrane is typically at H ₂Supply with the SiHCL of silicon compound gas in the environment ₃, SiHCl ₂, SiH ₄B Deng gas and impurity gas ₂H ₆Gas, PH ₃Deng gas, supply with 1000～1200 ℃ scope.

On the other hand, pre-treatment is the operation of removing at the surperficial existing natural oxide film of silicon single crystal substrate or particulate etc., particularly carry out building crystal to grow before, the surface that purifies the silicon single crystal substrate is indispensable processing.In order to remove natural oxide film or particulate, the normal method of using has at H ₂Or H ₂In/HCl the mixed-gas environment, substrate is heat-treated with near the high temperature 1100 ℃.In addition, near room temperature, can implement method, known have Wet-type etching, combination hydrogen fluoride gas and the water vapour, the Ar electricity slurry that use rare fluorspar acid solution to handle, but have at the oxide film of growing up again at once after the processing, on substrate, produce the problem of surface irregularity, corrosion treatment equipment etc., think present situation with aforesaid high-temperature heat treatment for the most suitable.

But, have the inadequate situation of inspiratory effects as above-mentioned Jingjing circle of heap of stone.This is because become the substrate of Jingjing circle of heap of stone, and through the high-temperature step more than 1000 ℃, oxygen is separated out nuclear or oxygen and gone out thing and almost destroy, and can't reach air-breathing function.Pre-treatment before the method in the past, building crystal to grow is not easy to remove fully natural oxide film in the temperature range less than 1000 ℃.Thereby, must carry out in the temperature range more than 1000 ℃ during pre-treatment, therefore method in the past can't exempt the reduction of Jingjing circle gettering efficiency of heap of stone.

To this kind substrate,, before or after forming epitaxial layer, must carry out needing considerable time in order to form the thermal treatment of BMD in order to obtain inspiratory effects.In particular for obtaining inspiratory effects and when forming necessary BMD, must be with low temperature and for a long time wafer is heat-treated.

Summary of the invention

First purpose of the present invention is to provide a kind of manufacture method of wafer, can shorten for the heat treatment time of giving the IG ability when making wafer and can produce high IG ability wafer in large quantities.

Second purpose of the present invention is to provide a kind of manufacture method of wafer, when making the annealing wafer, can heat-treat efficiently, increase the production sheet number of annealing wafer, this annealing wafer for the oxygen that forms aforesaid DZ layer toward outside DIFFUSION TREATMENT, for the thermal treatments such as thermal treatment of the generation BMD that gives the IG ability, essential considerable time and cost.

The 3rd purpose of the present invention is to provide a kind of manufacture method of Jingjing circle of heap of stone, making as above-mentioned Jingjing bowlder of heap of stone, can heat-treat efficiently, promotes the productivity of the Jingjing circle of heap of stone with good inspiratory effects.

In order to reach aforementioned first purpose, the manufacture method of wafer of the present invention, contain following step at least: silicon wafer ingot heat treatment step, the silicon single crystal of silicon wafer ingot state is heat-treated; And the wafer procedure of processing, the silicon wafer ingot that this is heat treated is processed into wafer.

So, give IG ability by the silicon single crystal of silicon wafer ingot state is heat-treated, can be the thermal treatment of carrying out behind the processing wafer in advance efficiently in the past, can promote productivity significantly.

At this moment, at aforesaid silicon wafer ingot heat treatment step, to form inner tiny flaw (BMD) at aforementioned silicon single crystal for good.

That is, a kind of manufacture method of wafer is provided, wherein have following step: BMD at least and form step, the silicon single crystal of silicon wafer ingot state is heat-treated, in order to form inner tiny flaw (BMD) in inside; And the wafer procedure of processing, the silicon wafer ingot that will be formed with aforementioned inner tiny flaw (BMD) is processed into wafer.

So, at silicon wafer ingot heat treatment step (situation that BMD forms step, first heat treatment step that is called being arranged) silicon single crystal of silicon wafer ingot state is heat-treated in advance in the present invention, in silicon wafer ingot procedure of processing, the silicon wafer ingot is processed into wafer, with the silicon single crystal of wafer state was applied the thermal treatment relatively time that forms BMD in the past, can efficient heat-treat well.Therefore, can efficient form BMD well, can produce the wafer of high IG ability in large quantities.Can just supply with the wafer of high IG ability from beginning to back steps such as assembly steps again.

Can also after aforementioned wafer procedure of processing, have the wafer heat treatment step that aforementioned wafer is heat-treated again.

In order to reach aforementioned second purpose, the manufacture method of annealing wafer of the present invention, contain following step at least: silicon wafer ingot heat treatment step, the silicon single crystal of silicon wafer ingot state is heat-treated; The wafer procedure of processing, the silicon wafer ingot that this is heat treated is processed into wafer; And the wafer heat treatment step, in order to aforementioned wafer is heat-treated (, the situation that is called second heat treatment step being arranged) in the present invention.

So, at silicon wafer ingot heat treatment step, silicon single crystal to silicon wafer ingot state is heat-treated in advance, in the wafer procedure of processing, after the silicon wafer ingot is processed into wafer,, this wafer is heat-treated at the wafer heat treatment step, with wafer was applied 2 sections heat-treating methods relatively the time in the past, can efficient heat-treat well.Because can shorten the thermal treatment of wafer state, can also reduce that wafer is produced metallic pollution again.

In aforementioned wafer procedure of processing, be good with the wafer that aforementioned heat treated silicon wafer ingot is processed into mirror-like.

In wafer procedure of processing so, by to be processed into the wafer of mirror-like at the heat treated silicon wafer ingot of silicon wafer ingot heat treatment step, after forming the wafer heat treatment step of DZ layer, because do not need to make the DZ layer to reduce the mirror ultrafinish of thickness, can make the field with directly be used in assembly at the resultant thicker DZ layer of wafer heat treatment step.

At this moment, after being processed into the wafer of aforementioned mirror-like, can also have the building crystal to grow step that on this wafer, forms epitaxial layer.

In order to reach aforementioned the 3rd purpose, the invention provides a kind of manufacture method of Jingjing circle of heap of stone, contain following step at least: silicon wafer ingot heat treatment step, the silicon single crystal of silicon wafer ingot state is heat-treated; The wafer procedure of processing is processed into the wafer of mirror-like with this through heat treated silicon wafer ingot; And the building crystal to grow step, in order on aforementioned wafer, to form epitaxial layer.

So, by silicon wafer ingot heat treatment step, in advance the silicon single crystal of silicon wafer ingot state is heat-treated, in the wafer procedure of processing, after the silicon wafer ingot is processed into wafer,, on this wafer, form epitaxial layer in the building crystal to grow step, with wafer was applied heat-treating methods relatively the time in the past, can efficient carry out the heat place well and bury.

Aforementioned silicon wafer ingot heat treatment step, the thermal treatment of carrying out more than 700 ℃ with the silicon single crystal to silicon wafer ingot state is good.

So, carry out thermal treatment more than 700 ℃, can form sufficient BMD in inside by silicon single crystal to silicon wafer ingot state.Again, aforementioned silicon wafer ingot heat treatment step is good to carry out more than 30 minutes 8 hours in the thermal treatment temp below 1100 ℃ with interior thermal treatment.

Heat-treat in the thermal treatment temp below 1100 ℃, can heat-treat in the mode that can not produce single crystal transposition or slip.Again, by more than 30 minutes 8 hours with interior thermal treatment, can give good IG ability.

Thereby aforementioned silicon wafer ingot heat treatment step is good to carry out more than 30 minutes 8 hours in the thermal treatment temp below 1100 ℃ more than 700 ℃ with interior thermal treatment.

Carry out silicon wafer ingot heat treatment step in temperature range like this, can not produce single crystal transposition or slip, can form sufficient BMD.Again, carry out silicon wafer ingot heat treatment step with the time like this, can give good IG ability.

Step Jingjing bowlder of heap of stone particularly, aforementioned silicon wafer ingot heat treatment step is good to carry out more than 30 minutes 8 hours in the thermal treatment temp below 900 ℃ more than 700 ℃ with interior thermal treatment.

Heat-treat in this temperature range, when forming epitaxial layer afterwards, can not produce the epitaxial layer defective, can form abundant BMD from the BMD that exposes the substrate wafer surface.Again, heat-treat step with the time like this, can give good IG ability.

The heat-up rate of aforementioned silicon wafer ingot heat treatment step is heat-treated to good with 0.5 ℃/minute～10 ℃/minute.

By heat-treating, can in the silicon wafer ingot, form stabile BMD at this heat-up rate.Again, in order to separate out BMD to high-density, BMD separates out the generation temperature region of nuclear, for example more than 500 ℃ the time, to heat up to good at leisure below 5 ℃/minute.When the zone low (less than 500 ℃), be treated to good with about 10 ℃/minute heat up comparatively at high speed than this temperature.

Aforementioned wafer heat treatment step is good to form nondefective zone (DZ layer) at aforementioned crystal column surface.

So,, form the DZ layer, can be manufactured near the formation of crystal column surface and have good crystalline DZ wafer at crystal column surface by the wafer heat treatment step.Silicon wafer ingot particularly of the present invention thermal treatment forms BMD because in advance the silicon wafer ingot single crystal of silicon wafer ingot state is heat-treated, and can heat-treat in the short period of time with simple program and form the DZ layer.

Aforementioned wafer heat treatment step is with more than 900 ℃ below 1300 ℃, and carrying out more than 5 minutes 16 hours is good with interior thermal treatment.

Heat treatment step by carrying out at this temperature range and heat treatment time can not produce the mode of slip with wafer, forms the DZ layer with abundant thickness.

Aforementioned wafer heat treatment step, heat-up rate is to heat up to good more than 5 ℃/minute.

So, because the present invention heat-treats the silicon single crystal of silicon wafer ingot state in advance at silicon wafer ingot heat treatment step, thus wafer is carried out the wafer heat treatment step, can be faster from the heat-up rate of beginning than method in the past, can the shortening heat treatment time.And, because carry out silicon wafer ingot heat treatment step, even can also obtain having the annealing wafer of sufficient bmd density and DZ layer with heat-up rate like this.

Aforesaid building crystal to grow step can be carried out building crystal to grow with the temperature more than 1000 ℃ after carrying out pre-treatment with the temperature more than 1000 ℃.

So, the present invention carries out building crystal to grow by after carrying out pre-treatment in the temperature more than 1000 ℃ in the temperature more than 1000 ℃, can remove natural oxide film fully in pre-treatment, can efficient carry out high-quality building crystal to grow well.Particularly because form the nuclear of separating out of BMD fully with silicon wafer ingot state, even, also can make the wafer that inspiratory effects can not reduce with good IG ability by high-temperature step formation epitaxial layer like this in beginning.

So, by to silicon single crystal doping nitrogen, can easily form DZ layer or BMD layer by thermal treatment.

Again, to silicon single crystal doping nitrogen, the defective of the epitaxial layer after the building crystal to grow step is less by so, can efficient makes the wafer of high IG effect well.

Aforementioned silicon single crystal is by Czochralski method (Czochralski method; The CZ method) makes the crystallization in quasi-full crystallization (NPC) district form.

So during crystallization, in for example later step during, can be used as that the DZ layer is thicker, the wafer of better quality as the annealing wafer.

Again, so crystallization is as Jingjing bowlder of heap of stone, the wafer that the defective of epitaxial layer is few, can be used as better quality.

The silicon single crystal of aforementioned silicon wafer ingot state is to use the silicon wafer ingot that cuts into the cylindric silicon wafer bulk state of crossing through skiving after the silicon wafer ingot of single crystal pull-up device pull-up state former state shape or the pull-up by Czochralski method.

The present invention can efficient form BMD at single crystal because of the silicon wafer ingot of silicon wafer bulk state like this being heat-treated and forming BMD in inside goodly.

The silicon wafer ingot of the so-called single crystal pull-up of the present invention device pull-up state former state shape, except passing through by the thing behind the firm pull-up single crystal of Czochralski method, also comprise after the pull-up from the silicon wafer ingot and cut off the thing that conus portion, terminal part form, or with its etc. cut into the thing that several silicon wafer pieces form.

During according to the manufacture method of wafer of the present invention,, can provide the wafer of high IG ability to back steps such as assembly steps because form BMD with silicon wafer ingot state beginning to heat-treat.Again,, can efficient carry out well, can shorten significantly, can promote the productivity that wafer is made by this in order to give the heat treatment time of IG ability by once forming the thermal treatment of BMD in large quantities.

During according to the manufacture method of annealing wafer of the present invention,, can efficient form the thermal treatment of BMD well because form BMD with silicon wafer ingot state beginning to heat-treat.By this, can promote the productivity of making the annealing wafer.And, because can shorten heat treatment time, can also reduce metallic pollution to wafer at wafer state.

And, during according to the manufacture method of annealing wafer of the present invention, because form BMD with silicon wafer ingot state, even form epitaxial layer in wafer processing back beginning to heat-treat, BMD also can not eliminate, and can make the Jingjing circle of heap of stone with high IG ability that highdensity BMD separates out.Again, be not under wafer state, to heat-treat because form the thermal treatment of BMD, but under silicon wafer ingot state, heat-treat, can a large amount of wafer (when being converted into wafer) of primary treatment, can promote productivity.

Description of drawings

Fig. 1 is the schema of an example of wafer manufacturing step of the present invention.

Fig. 2 is the schema of another example of wafer manufacturing step of the present invention.

Fig. 3 is the explanatory view of an example of the employed horizontal type heat treatment furnace of silicon wafer ingot heat treatment step of the present invention.

Fig. 4 is the explanatory view of an example of the employed vertical heat treatment furnace of silicon wafer ingot heat treatment step of the present invention.

Fig. 5 is for cutting into the silicon wafer ingot of the silicon single crystal of silicon wafer bulk state after the pull-up.

Fig. 6 is the explanatory view of an example of the employed vertical heat processing apparatus of wafer thermal treatment.

Fig. 7 is the explanatory view of an example of the brilliant boat of the employed thermal treatment of wafer thermal treatment.

Fig. 8 is the schema of an example of wafer procedure of processing of the present invention.

Fig. 9 is the step general flowchart of annealing wafer of the present invention.

Figure 10 is the step general flowchart of Jingjing circle of heap of stone of the present invention.

Figure 11 is the explanatory view of an example of Jingjing circle growth apparatuses of heap of stone.

[primary clustering nomenclature]

1 silicon wafer ingot, 2 conus portions

3 terminal parts, 4 silicon wafer pieces

10 heat treatment furnaces, 11 treatment chambers

12 well heaters, 13 support portions

21 treatment chambers, 22 well heaters

30 vertical heat treatment furnaces, 31 treatment chambers

W wafer 32 well heaters

33 gas introduction tubes, 34 gas exhaust pipes

Brilliant boat 41 linking parts of 40 thermal treatments

42 pillars, 43 mounting portions

50 building crystal to grow devices, 51 treatment chambers

The control of 52 infrared(ray)lamps, 53 mass rates

54 radiation thermometers

Embodiment

Below, describe the present invention in detail.

The present inventor learns when making the wafer of high IG ability, heat-treat at silicon wafer ingot state, formation can promote the BMD of IG effect, be wafer by being processed into, the wafer of can efficient making the high IG ability that is formed with BMD well, even the DZ layer subsequently forms or epitaxial layer forms step, can fully keep bmd density.

In the past, at the annealing of silicon wafer ingot state (following also have the silicon wafer of being called ingot annealed situation), based on the compound semiconductor technology that for example GaAs was carried out, carry out in order to improve electrical characteristic specially (for example, with reference to the spy open flat 6-196430 communique, the spy opens flat 6-31854 communique).The present invention is by at silicon wafer ingot state silicon single crystal being applied the thermal treatment that forms BMD, coming the short period of time to produce the wafer of high IG ability in large quantities with so thermal treatment is different.That is wafer manufacture method of the present invention is characterized by, and forms BMD in the silicon single crystal of silicon wafer ingot state, subsequently, carries out wafer processing.

The present invention is so by forming BMD at silicon wafer ingot state, it is carried out wafer processes to make and composes the wafer be added with the IG ability, for example when making the annealing wafer subsequently, can omit the heat-treat condition of giving this IG ability or oversimplified, can the shortening heat treatment time.For example make Jingjing bowlder of heap of stone, can be used as the high wafer of inspiratory effects by on this kind wafer, forming epitaxial layer.Again, because heat-treat at silicon wafer ingot state, with the thermal treatment that formed BMD at wafer state in the past relatively the time, because needn't be with the brilliant boat of wafer thermal treatment, once thermal treatment in large quantities (when being converted into wafer) can promote heat treatment efficiency significantly.

On concrete, the silicon single crystal of silicon wafer ingot state is carried out thermal treatment more than 700 ℃, carry out wafer processing subsequently.Particularly the silicon single crystal of silicon wafer ingot state is heat-treated, at the heat treatment step of the inner shape BMD of silicon wafer ingot, with more than 700 ℃ below 1100 ℃, carrying out more than 30 minutes 8 hours is good with interior thermal treatment.Again, heat-up rate is heat-treated with 0.5 ℃/minute～10 ℃/minute, can form stabile BMD.

By heat-treating, can prevent whole generation transposition of silicon wafer ingot or slip in the thermal treatment temp below 1100 ℃.Again,, sufficient BMD can be formed, and by in the heat-treated more than 700 ℃, the BMD that the later step annealing steps of wafer state (for example) can not be eliminated can be formed on by in the heat-treated more than 700 ℃.

In temperature range like this, the silicon wafer ingot is for example carried out more than 30 minutes keeping with interior constant temperature in 8 hours or the constant temperature in plural number stage is when keeping thermal treatment, can form when having abundant BMD,, can give good IG ability because residual on thereafter the step BMD ground that also can not disappear.Treatment time is not particularly limited, even this treatment time is longer also harmless, but from the time benefit and obtain good IG ability, serving as suitable about above-mentioned scope.At this moment, heat-up rate heats up to good with 0.5 ℃/minute～10 ℃/minute.

Again, the silicon wafer ingot is that the crystallization or the crystallization in NPC district that is doped with nitrogen at silicon single crystal is good.

When the silicon single crystal that particularly uses nitrogen to mix to form comes thermal treatment to form, obtain the oxygen precipitate easily, and crystallization cause defective such as COP becomes easily dissolved because of thermal treatment in crystallization inside.By using this kind silicon single crystal, when the step that for example will form the DZ layer is carried out afterwards, can make wafer effectively with wide nondefective zone, high IG effect.

Again, the crystallization in NPC district also similarly has wide nondefective zone to become, the wafer of high IG effect is good.The crystallization in NPC district is to grow up by crystallization control pull-up condition, though the atom emptying aperture superfluous do not have that crystalline growth imports defect area (the Nv district situation that is called is arranged) though the territory, and grid between the Siliciumatom surplus do not have the crystallization of crystalline growth importing defect area (the Ni district situation that is called is arranged).

Particularly known in the Nv and the Ni district in NPC district, oxygen is separated out the movement difference.When showing that the different oxygen of this kind are separated out movement, for example, be preferably by the low-temperature region from 300～500 ℃ in the silicon wafer ingot stage, with about 0.5～2 ℃/minute slow heat-up rate from the low temperature BMD that grows up that heats up at leisure, can make at the oxygen in Nv or Ni district and separate out the movement homogenizing, can in face, form stabile BMD in the mode that does not rely on Nv or Ni district.

Because productivity reduced significantly when wafer state carries out this kind thermal treatment in the past, can't implement on the reality.But,, also can once handle in large quantities during the stage at the silicon wafer ingot, can keep high productivity even carry out thermal treatment so slowly.

Again, the silicon single crystal of silicon wafer ingot state be meant shape after the firm pull-up of single crystal pull-up device silicon wafer ingot or cylinder grinding, cut into the silicon wafer ingot of silicon wafer bulk state.Single crystal by the pull-up of single crystal pull-up device is formed with so-called tapering and terminal part, with this kind silicon wafer ingot state (in addition, comprising the state that conus portion and terminal part form and the state that is divided into plural silicon wafer piece removed), can carry out the annealing of silicon wafer ingot.

Again, (before the section) is partitioned into plural silicon wafer piece with silicon wafer ingot cylinder grinding usually before the wafer processing, can also heat-treat through the silicon wafer bulk state that cylinder grinding forms by this kind.At this moment because on the top layer of silicon wafer piece because cylinder grinding can produce the metal dirt, be preferably use acid etching to remove about 100～500 microns on top layer after, heat-treat.

Again, the present inventor learns and can make a kind of annealing wafer, when making the annealing wafer, has the BMD that promotes the IG effect by silicon wafer ingot former state being heat-treated form, carry out wafer processing thereafter, and then heat-treat at wafer state, can efficient heat-treat, form fully BMD well, and can also form the DZ layer fully.

The manufacture method of annealing wafer of the present invention is characterised in that to have following steps: first heat treatment step, the silicon single crystal of silicon wafer ingot state is heat-treated; The wafer procedure of processing, the silicon wafer ingot that this is heat treated is processed into wafer; And second heat treatment step, wafer is heat-treated.Particularly first heat treatment step that the silicon single crystal of silicon wafer ingot state is heat-treated is the heat treatment step that forms BMD, and second heat treatment step of thermal treatment wafer is to form not have the heat treatment step that falls into district's (DZ floor) on crystal column surface.

When learning the silicon wafer ingot of the silicon single crystal that makes the annealing of this kind silicon wafer ingot be adapted to conduct annealing donor wafer, can obtain good annealing wafer.It is good particularly applying the BMD that the thermal treatment more than 700 ℃ forms with silicon wafer ingot state.

The present invention puts on 2 segmentation thermal treatments of wafer in the past in order to form DZ layer and BMD, form the thermal treatment of BMD in the silicon wafer ingot stage, the thermal treatment of last wafer state by omitting or oversimplifying the thermal treatment that forms BMD, is shortened the heat treatment time that puts on wafer.That is, by form the thermal treatment of BMD at silicon wafer ingot state place, because needn't use the brilliant boat of the employed wafer thermal treatment of previous methods, the several a when thermal treatment can be carried out wafer state to ten several batch-wise deals, can promote heat treated efficient in batches significantly.And, heat treatment time can be shortened to about 1/2nd time in the past by can omit or oversimplify the thermal treatment that forms BMD in the thermal treatment of wafer state, can promote the productivity of annealing wafer significantly.

In order to form of the annealing (second heat treatment step) of DZ layer, because be to oversimplify the thing that 2 segmentation thermal treatments in the past form, mainly to heat-treat to good for the condition that forms the DZ layer at wafer state.Being specially more than 900 ℃ heating below 1300 ℃ 16 hours heat-treats with interior.Particularly being good more than 1100 ℃.Heat treatment time can be according to width of desired DZ layer etc. and is suitably set.

So, by the silicon single crystal of heat-treating at silicon wafer ingot state being carried out wafer processing, and then heat-treat, can make effectively and have the wide nondefective zone or the annealing wafer of high IG effect at wafer state.

And then, the present inventor learns and is making Jingjing bowlder of heap of stone, by for example the BMD with lifting IG effect is heat-treated, formed fully to silicon wafer ingot former state, carry out wafer processing thereafter, and then form building crystal to grow in its surface, can efficient heat-treat well, can make the Jingjing circle of heap of stone that is formed with BMD fully efficiently with high inspiratory effects.

The manufacture method of Jingjing circle of heap of stone of the present invention has following steps: heat treatment step, the silicon single crystal of silicon wafer ingot state is heat-treated; The wafer procedure of processing is processed into the wafer of mirror-like with this through heat treated silicon wafer ingot; And the building crystal to grow step, in order on the wafer that forms through mirror ultrafinish, to form epitaxial layer.Particularly the heat treatment step that the silicon single crystal of silicon wafer ingot state is heat-treated is the heat treatment step that forms BMD.

When the present inventor learns the silicon wafer ingot of the silicon single crystal that makes the annealing of silicon wafer ingot be adapted to conduct Jingjing circle of heap of stone raw material, can obtain good Jingjing circle of heap of stone.In the past, before or after forming epitaxial layer, must carry out in order to form the thermal treatment of BMD.But, the brilliant boat of employed thermal treatment unit of wafer thermal treatment and wafer thermal treatment, once the wafer that can install is that thermal effectiveness is low about 100 at most.But by forming the thermal treatment of BMD at silicon wafer ingot state, because needn't use the employed brilliant boat of previous methods, the several a when thermal treatment can be carried out wafer state to ten several batch-wise deals, can promote heat treatment efficiency in batches significantly.

Particularly apply the thermal treatment below 900 ℃ more than 700 ℃ at silicon wafer ingot state, it is good forming BMD.By heat-treating below 900 ℃, can prevent whole generation transposition of silicon wafer ingot or slip, can prevent to expose BMD at crystal column surface, produce defective at epitaxial layer.By heat-treating, can prevent to eliminate in the building crystal to grow step at the BMD of silicon wafer ingot state formation in the temperature more than 700 again.

Thereby, apply the thermal treatment below 900 ℃ more than 700 ℃ by silicon single crystal to silicon wafer ingot state, when not producing the epitaxial layer defective, can be formed on the BMD of the suitable size that brilliant step of heap of stone can not eliminate fully in silicon wafer ingot inside.Be specially the thermal treatment temp below 900 ℃ more than 700 ℃, keep more than 30 minutes 8 hours with interior constant temperature, or the constant temperature that carries out the plural number section keeps thermal treatment, again, heat-treat with 0.5 ℃/minute～10 ℃/minute by heat-up rate, can form stabile BMD.

Again, the silicon wafer ingot is to be good with the crystallization or the crystallization in NPC district that are doped with nitrogen at silicon single crystal.

When the silicon single crystal that particularly uses the nitrogen doping to form came thermal treatment to form, crystallization cause defectives such as COP became easily dissolved and obtain the oxygen precipitate easily in crystallization inside because of thermal treatment.By using this kind silicon single crystal, can also make wafer effectively with wide nondefective zone, high IG effect in the building crystal to grow step.

Again, the crystallization in NPC district also similarly can obtain having the wafer of wide nondefective zone, high IG effect.

Form the method for epitaxial layer, particularly use method in the past also harmless, for example, be preferably the high-temperature step that has more than 1000 ℃ and handle before, subsequently, carry out building crystal to grow in the temperature more than 1000 ℃.On concrete, the building crystal to grow of silicon crystalline membrane is at H ₂Supply with the SiCl of silicon compound in the environment ₄, SiHCl ₃, SiH ₂Cl ₂, SiH ₄Deng gas, and the B of impurity gas ₂H ₆Gas or PH ₃Deng gas, carry out 1000～1300 ℃ temperature provinces.

On the other hand, the pre-treatment of before building crystal to grow, being carried out, this operation is particularly carried out before the building crystal to grow in order to remove natural oxide film and the particulate that is present in the silicon single crystal substrate surface, and the surface cleaning of silicon single crystal substrate is indispensable processing.For remove oxide film and particulate the normal method of using, at H ₂Or H ₂In the mixed-gas environment of/HCl, with 1000 ℃～1300 ℃, near the method that substrate is heat-treated of the high temperature 1100 ℃ particularly.

The silicon wafer ingot that can thermal treatment at the shape of like this silicon single crystal forms is carried out wafer processing, as the starting material of Jingjing circle of heap of stone, can efficient make well do not have defective, the Jingjing circle of heap of stone of high IG effect.

Following with reference to diagram, illustrate in greater detail the manufacture method of wafer of the present invention.Fig. 1 and Fig. 2 are the general flowcharts of wafer step of the present invention.

(cultivation of silicon wafer ingot)

At first, by the CZ method regulate oxygen concn (or nitrogen concentration), resistivity waits silicon single crystal silicon wafer ingot is grown up.This pull-up method is not particularly limited, the method that can use in the past to be carried out.Particularly with less conditions of crystallization cause defective such as COP, it is good carrying out pull-up silicon wafer ingot.

Particularly, can grow up and form the silicon single crystal of DZ layer, BMD easily by the nitrogen that in silicon single crystal, mixes.In the present invention, cultivate the silicon single crystal of doping nitrogen, passing through Czochralski method (Czochralski method; When the CZ method) cultivating silicon single crystal, add nitride in advance or add nitride in silicon melt, make environmental gas contain nitrogen etc. in quartz crucible, nitrogen can mix in silicon single crystal.At this moment, by adjusting amount or the concentration of oxide gas or the importing time etc. of nitride, the nitrogen doping in can crystallization control.

By using the silicon single crystal in quasi-full crystallization (NPC) district, can when annealing with wafer state subsequently, make the annealing wafer of thicker DZ layer again.When making the silicon single crystal of this quasi-full crystallizing field, for example, when cultivating silicon single crystal by Czochralski method, can the limit ratio V/G of control pull-up speed V and near the axial crystallization temperature gradient G of the pull-up the solid-liquid interface, the crystallization pull-up is carried out on the limit, can be comprehensive in the crystallization transverse section, the silicon single crystal of pull-up quasi-full crystallizing field (NPC).

(annealing of silicon wafer ingot: BMD forms step, first heat treatment step)

Then,, heat-treat, form BMD in inside with silicon wafer ingot shape attitude with so cultivating the silicon wafer ingot that forms.That is (before the wafer procedure of processing) heat-treats before the slicing step that is processed into the wafer shape.At this moment, heat-treat with the condition that forms BMD.At this moment, silicon wafer ingot annealing be by the silicon wafer ingot of the shape of single-crystal production apparatus (silicon wafer ingot pull-up device) pull-up just or pull-up after cylinder grinding, cut-out become the silicon wafer bulk state and carry out.That is, can before or after cylinder grinding silicon wafer ingot peripheral part, implement.

At first, illustrate that carrying out the silicon wafer ingot with firm pull-up shape silicon wafer ingot anneals the example of one of them (Fig. 1).

At this example, do not remove conus portion or terminal part by the silicon wafer ingot of single-crystal production apparatus pull-up, with the state that is not partitioned into plural silicon wafer piece the silicon wafer ingot is put into heat treatment furnace, form the thermal treatment of BMD.

At this moment, thermal treatment unit is not particularly limited, wherein heat-treating to good under the bulk state of this kind silicon wafer ingot.Horizontal type heat treatment furnace as shown in Figure 3 is good.Fig. 3 is a horizontal type heat treatment furnace summary, and this heat treatment furnace 10 has the treatment chamber 11 of quartz or SiC system, the state that is not partitioned into plural silicon wafer piece directly can be put into silicon wafer ingot 1, possesses having heaters 12 heat-treated members such as grade in its outside.This silicon wafer ingot 1 is to support (can also dispose the support portion at silicon wafer ingot central part according to necessity) by the support portion 13 that can support conus portion and terminal part.Use this kind device to heat-treat with the heat-treat condition that can form BMD.

When the silicon wafer ingot of the firm pull-up shape of this kind is heat-treated,, be preferable because can heat-treat few state such as polluting or can not form under the state such as distortion.Again, can once heat-treat, can handle very a large amount of wafer (when being converted into wafer) the silicon wafer ingot.

Then, the example that shows other form.Following example is not the shape of firm pull-up, but to pull-up after cylinder grinding, cut into the silicon wafer ingot of silicon wafer bulk state, carry out silicon wafer ingot annealed example (Fig. 2).

Cylinder grinding subsequently, as shown in Figure 5, cuts off the conus portion 2 and the terminal part 3 of silicon wafer ingot 1, and then cuts into the silicon wafer piece 4 of plural number in the side of the silicon wafer ingot of silicon wafer ingot incubation step institute pull-up, obtains the silicon wafer piece of crystal silicon ingot.

Subsequently, this blocky crystal silicon ingot is heat-treated.Again, carry out so round sample grinding, the silicon wafer piece adds man-hour, pollutes or the disruptive possibility because thermal treatment has to produce, and at first by etching solution, carries out hundreds of microns etching, remove attached to the metal impurity of silicon wafer ingot surface integral body etc.This etching solution for example can use, by HF/HNO ₃The acidic etching liquid that is constituted etc.

Subsequently, in silicon wafer bulk state former state, put into heat treatment furnace and heat-treat.Thermal treatment unit is not particularly limited, wherein can be with the silicon wafer piece of the silicon wafer ingot of this kind form, and with the example that block former state is heat-treated, thing as shown in Figure 4 is good.The heat treatment furnace 20 of Fig. 4 is devices that the silicon wafer piece 4 of silicon wafer ingot is heat-treated with vertical installation, wherein, with the silicon wafer piece 4 of silicon wafer ingot be dropped in heat treatment furnace 20 belows by in the processing to 21 that quartz or SiC constituted, by the form that well heater 22 heat-treated members such as grade that are disposed at its outside are heat-treated, also can be a kind of vertical heat treatment furnace.Use this kind heat treatment furnace to heat-treat with the heat-treat condition that can form BMD.Making this kind silicon single crystal become bulk and heat-treat, because heat treatment furnace can also miniaturization, is preferable.

So, when the silicon wafer bulk state that forms to pull-up after through the post grinding is heat-treated, because also needn't be with wafer with the brilliant boat of thermal treatment, can a large amount of silicon single crystal of primary treatment, be converted into when heat-treating with wafer state, once can thermal treatment unusual volume wafer.

Concrete heat-treat condition as above-mentioned silicon wafer ingot heat treatment step (BMD forms step, first heat treatment step), can suitably set according to desired specification, wherein, particularly, in the oxygen environment, when 700 ℃～1100 ℃ thermal treatments 30 minutes are to about 8 hours, can generate object BMD fully.In fact,, heat up, subsequently, fall slow heat-up rate with the high speed of about 10 ℃/minute of heat-up rates near the room temperature to 500 ℃, till the design temperature with about 0.5 ℃/minute～5 ℃/minute intensifications.Be warming up to design temperature (for example 1000 ℃) at leisure by this method, keep random time (for example 1 hour) at this design temperature.Subsequently, be cooled to 600 ℃ for good with about 5 ℃/minute cooling rate.So carry out, can form BMD on silicon wafer ingot middle-high density ground, this BMD heat-treats about 1000 ℃ with wafer state subsequently and forms the DZ layer or carry out building crystal to grow, also can not disappear.

(Silicon Wafer procedure of processing)

Then, will be processed into wafer through the silicon wafer ingot that silicon wafer ingot annealing like this forms.If in the time of accessing the wafer of high flat degree at least, its step is not particularly limited.This example after laminate (wafer) ((A) among Fig. 8), to this Silicon Wafer, is docile and obedient the section of single crystal silicon crystal ingot preface to implement oblique angle processing ((B) among Fig. 8), planarization (polishing as shown in Figure 8; Lapping), ((C) among Fig. 8), etching ((D) among Fig. 8), grind ((E) among Fig. 8) and wait each step, obtain the mirror ultrafinish wafer at last.Each step condition is not particularly limited, and wherein, slicing step ((A) among Fig. 8) is to use scroll saw to cut off, and planarisation step ((C) among Fig. 8) is to be undertaken by polishing (step) or smooth grinding (step).When for example polishing step, use the above free abrasive grain of #1500 to polish.Then, ((D) among Fig. 8 uses alkaline solution to carry out etching, and grinding steps ((E) among Fig. 8) can be implemented to make up the plural number section that grind on the two sides, the one side grinding forms and grind in etching step.Also implement the preceding uneven surface processing of planarization or the mirror-polishing (processing of minute surface oblique angle) of oblique angle portion etc. in oblique angle procedure of processing ((B) among Fig. 8) again.In addition, can also after the grinding or each step between washing step is set.

So, carry out silicon wafer ingot annealing after, can easily make the wafer of high IG ability.

The manufacturing of annealing wafer

Then, with reference to the manufacture method that illustrates annealing wafer of the present invention.Fig. 9 is the step general flowchart of annealing wafer of the present invention.

(cultivation of silicon wafer ingot, the annealing of silicon wafer ingot, wafer processing)

With the aforementioned silicon wafer ingot of similarly cultivating, carry out silicon wafer ingot annealing after, add the wafer that can easily make high IG ability man-hour at wafer.Again, improve the step of the crystal column surface state of mirror ultrafinish etc., can also behind second heat treatment step described later, carry out.

(silicon wafer ingot annealing: second heat treatment step)

Thermal treatment mirror ultrafinish wafer like this.Previous device can be directly used in the annealing of wafer.Can use vertical heat treatment furnace 30 as shown in Figure 6.This heat treatment furnace 30 is handled stove 31 32 pairs of treatment chamber internal heating of well heater on every side by being configured in, and from passivity gases such as gas introduction tube 33 importing argons, discharges unwanted gas from gas exhaust pipe 34 when thermal treatment.Object being treated plural pieces wafer W is configured in the treatment chamber 31 for being installed in the brilliant boat 40 of thermal treatment.The brilliant boat 40 of thermal treatment is as shown in Figure 7 thing.The brilliant boat 40 of this thermal treatment links these pillars by plural pillar 42, at the two ends of pillar linking part 41 is constituted.Pillar 42 is provided with the wafer mounting portion 43 of groove shape, wafer W can be installed, can keep wafer W.

The present invention can use than the simpler program of heat-treat condition in the past and implement thermal treatment because carry out the annealing of silicon wafer ingot by silicon wafer ingot heat treatment step (first heat treatment step).Therefore can shorten the time, make the good annealing wafer of productivity.

The heat-treat condition of wafer heat treatment step (second heat treatment step), its main purpose are to form nondefective zone (DZ layer) on crystal column surface, be preferably, more than 900 ℃ below 1300 ℃, thermal treatment more than 5 minutes 16 hours with the interior DZ layer of growing up.In the time of more than 900 ℃, can finish the formation of DZ layer in the short period of time, and can obtain sufficient DZ width.In the time of below 1300 ℃, be not easy to result from slips such as wafer distortion again.Again, heat treatment time, the width of DZ layer and suitably setting as requested.Setting-up time is long more, the easy more DZ width that obtains broad.

Particularly, DZ-IG thermal treatment in the past is to carry out high-temperature heat treatment after low-temperature heat treatment continuously, in order to form BMD and it can not eliminated, when annealing, wafer must heat up at leisure, yet, under the silicon wafer ingot state during, can implement apace in the intensification of this wafer annealing stage through thermal pretreatment as the present invention, even for example handle, can also obtain the bmd density wafer of annealing fully with the heat-up rate more than 5 ℃/minute.

By wafer step so, can efficient well the silicon wafer ingot be heat-treated, add the wafer annealed heating-up time is reduced significantly, can shorten the wafer annealing time.

And, the wafer annealing time more in short-term, metallic pollutions etc. also can reduce, can get wafer well.

The manufacturing of Jingjing circle of heap of stone

Then, with reference to the manufacture method that illustrates Jingjing circle of heap of stone of the present invention.Figure 10 is the step general flowchart of Jingjing circle of heap of stone of the present invention.

(cultivation of silicon wafer ingot)

At first, carry out the cultivation of silicon wafer ingot.Can cultivate silicon single crystal by the CZ method with above-mentioned same, at this moment,, can form BMD easily, can grow up and to reduce the silicon single crystal of epitaxial layer defective particularly by the nitrogen that in single crystal, mixes.

By silicon single crystal, can make the few Jingjing circle of heap of stone of epitaxial layer defective with quasi-full crystallization (NPC) district again.

(annealing of silicon wafer ingot)

The concrete heat-treat condition that goes up of silicon wafer ingot heat treatment step, specification and suitably setting as requested wherein, particularly in the oxygen environment, when 700 ℃～900 ℃ thermal treatments 30 minutes are to about 8 hours, can generate object BMD fully.In fact,, heat up, subsequently, fall slow heat-up rate with the high speed of about 10 ℃/minute of heat-up rates near the room temperature to 500 ℃, till the design temperature with about 0.5 ℃/minute～5 ℃/minute intensifications.Be warming up to design temperature (for example 800 ℃) at leisure by this method, keep random time (for example 4 hours) at this design temperature.Subsequently, be cooled to 600 ℃, then, be cooled to room temperature with the cooling rate about 2 ℃/minute with about 5 ℃/minute cooling rates.Can form highdensity BMD this moment, even the temperature about 1200 ℃, the thermal treatment that forms the short period of time of handling as epitaxial layer also can not disappear.

(wafer procedure of processing)

Then, to so carrying out wafer processing through the annealed silicon wafer ingot of silicon wafer ingot.Add man-hour to an interarea of wafer at least at wafer, apply mirror-polishing and grind, if can access the wafer of high flat degree, this step is not particularly limited.For example, as above-mentioned, can obtain the mirror ultrafinish wafer according to order shown in Figure 8.

(building crystal to grow step)

Form epitaxial layer on the surface of mirror ultrafinish wafer like this, the formation of epitaxial layer is surperficial existing natural oxide film or the particulate of removing at the silicon single crystal substrate in pre-treatment.At H ₂Or H ₂In/HCl the mixed-gas environment, substrate is heat-treated with near the high temperature 1100 ℃.

Then be the method that forms epitaxial layer, can use method in the past.For example at H ₂Supply with the SiCl of silicon compound in the environment ₄, SiHCl ₃, SiH ₂Cl ₂, SiH ₄Deng gas, and the B of impurity gas ₂H ₆Gas or PH ₃Deng gas, handle 1000～1300 ℃ temperature province.

Again, the employed device of building crystal to grow can use device in the past.For example, can use the building crystal to grow device in same treatment chamber, to carry out pre-treatment and building crystal to grow as shown in figure 11.This building crystal to grow device 50 is to accommodate wafer W in treatment chamber 51.Figure 11 still can also accommodate plural wafer for accommodating a wafer W.The gas that imports from an end of above-mentioned treatment chamber 51 is discharged gas from an other end of this treatment chamber 51 behind contact wafer W.Mobile above-mentioned gas in treatment chamber 51 is independent H ₂Gas, with H ₂The HF gas that gas dilution forms, with H ₂The HCl gas that gas dilution forms, with H ₂The SiHCl that gas dilution forms ₃Gas etc. are one of pre-treatment and the necessary gas of growth epitaxial layer, and each composition gas all is that the limit accurately imports in the treatment chamber 51 on the dominant discharge limit via mass flow controller 53.HF is a liquid at normal temperature, but because its vapour pressure is big, gasification easily, makes gasification composition and H ₂Mix and be supplied to treatment chamber 51.The outside handling 51 along the interarea of a side, disposes infrared(ray)lamp 52, can control the Heating temperature of wafer W according to the energising amount.Again,, dispose radiation thermometer 54, the wafer temperature in can monitoring step in the interarea side of the opposite side of treatment chamber 51.Certainly, pre-treatment portion can also be arranged to different treatment chambers with building crystal to grow portion.

As above-mentioned, by making Jingjing circle of heap of stone, can efficient make the Jingjing circle of heap of stone that the epitaxial layer defective is few, have highdensity BMD well, can promote productivity significantly.

Embodiment and comparative example below are described.

(embodiment 1)

(cultivation of silicon wafer ingot)

By the CZ method, the growth oxygen concn is 13～15 * 10 ¹⁷Atoms/cm ³[oldASTM], nitrogen concentration are 5～9 * 10 ¹²Atoms/cm ³Silicon single crystal silicon wafer ingot.This silicon wafer ingot of cylinder grinding, cut off and to become plural silicon wafer piece, obtaining diameter and be about 300 millimeters, length is about 30 centimeters silicon wafer ingot.

(annealing of silicon wafer ingot: BMD forms step)

To above-mentioned silicon wafer ingot, heat-treat with the state former state of silicon wafer ingot, carry out forming the BMD formation step of BMD in inside.At first, use by HF/HNO ₃The acidic etching liquid that is constituted carries out about 200 microns etchings, removes the metal impurity of contaminated surface.

Then,, put into heat treatment furnace shown in Figure 4, heat-treat in crystal silicon ingot state former state.

Thermal treatment is from room temperature to 500 ℃, with 10 ℃ of/minute intensifications of heat-up rate, subsequently, is warming up to 1000 ℃ with about 1 ℃/minute, keeps 2 hours at 1000 ℃.Subsequently, be cooled to 600 ℃, subsequently, with about 2 ℃/minute, be cooled to room temperature with about 5 ℃/minute cooling rates.What the environment during this thermal treatment used is oxygen.

By this, can implement thermal treatment once, when the thermal treatment amount is converted into wafer, be 4 minutes of the brilliant boat of common wafer thermal treatment in batches.

(wafer procedure of processing)

The wafer procedure of processing is for coming the silicon wafer ingot after treatments B MD forms step by step shown in Figure 8.Slicing step ((A) among Fig. 8) uses scroll saw to cut off, after the oblique angle procedure of processing ((B) among Fig. 8), planarisation step ((C) among Fig. 8) uses the above free abrasive grain of #1500 to polish, ((D) among Fig. 8, the alkaline solution of working concentration 50%NaOH carries out etching at etching step.Grinding steps subsequently ((E) among Fig. 8) is to carry out 3 sections grindings that grind on the two sides, one side is ground, one side is ground, and obtains the wafer of high flat degree and mirror-polishing.Subsequently, carry out after scouring.Can obtain the Silicon Wafer of 300 millimeters of about 300 diameters from above-mentioned 30 centimeters silicon wafer ingot.

Resulting wafer like this uses the infrared photography method to estimate the result of bmd density, is 3 * 10 ⁹Individual/cm ³, have sufficient bmd density.That is can obtain the wafer of high IG ability.Therefore, use this kind wafer, for example form the DZ layer in the back step and make annealing during wafer, because do not need to form the low-temperature heat treatment of BMD, only need be at wafer state in order to form the thermal treatment of DZ layer, shortening heat treatment time significantly.

(embodiment 2)

(cultivation of silicon wafer ingot)

By the CZ method, the growth oxygen concn is 13～15 * 10 ¹⁷Atoms/cm ³The silicon single crystal silicon wafer ingot of [oldASTM].This silicon single crystal is the grow up crystallization in NPC district of crystallization control growth rate.By with this silicon wafer ingot, cut off and to become plural silicon wafer piece, obtaining diameter and be about 300 millimeters, length is about 30 centimeters silicon wafer ingot.

Subsequently and embodiment 1 similarly, carry out BMD and form step, wafer processing system, obtain the Silicon Wafer of 300 millimeters of about 300 diameters.The wafer that so obtains uses the infrared photography method to estimate the result of bmd density, is 3 * 10 ⁹Individual/cm ³, have sufficient bmd density, can obtain the wafer of high IG ability.

(comparative example 1)

Identical with embodiment 1 and 2, make the silicon wafer ingot after, do not carry out heat-treating and carry out BMD and form step with silicon wafer ingot state, be processed into wafer separately, estimate bmd density with the foregoing description 1 and 2 the same terms.

Because by the wafer that above-mentioned silicon wafer ingot obtains, do not carry out heat-treating and not forming BMD with silicon wafer ingot state, also almost can't detect BMD even if carry out above-mentioned evaluation.Therefore, this wafer is used when for example annealing wafer, must form BMD and make the thermal treatment of its growth with wafer state.

(embodiment 3)

(cultivation of silicon wafer ingot)

(silicon wafer ingot annealing: first heat treatment step)

To above-mentioned silicon wafer ingot, carry out first thermal treatment with the state former state of silicon wafer ingot, at first, use by HF/HNO ₃The acidic etching liquid that is constituted carries out about 200 microns etchings, removes the metal impurity of contaminated surface.

By this, can implement thermal treatment once, when the thermal treatment amount is converted into wafer, be common 4 fens batches of the brilliant boat of wafer thermal treatment.

(wafer procedure of processing)

The wafer procedure of processing is handled for step as shown in Figure 8.Slicing step ((A) among Fig. 8) uses scroll saw to cut off, after the oblique angle procedure of processing ((B) among Fig. 8), planarisation step ((C) among Fig. 8) uses the above free abrasive grain of #1500 to polish, ((D) among Fig. 8, the alkaline solution of working concentration 50%NaOH carries out etching at etching step.Grinding steps subsequently ((E) among Fig. 8) obtains the wafer of high flat degree and mirror-polishing for carrying out 3 sections grindings that grind on the two sides, one side is ground, one side is ground.Subsequently, carry out after scouring.Can obtain the Silicon Wafer of 300 millimeters of about 300 diameters from above-mentioned 30 centimeters silicon wafer ingot.

(wafer annealing: second heat treatment step)

Be 75 with 1 heat-treats in batches.

Thermal treatment unit uses vertical heat treatment furnace shown in Figure 6, and above-mentioned wafer transfer in the brilliant boat of thermal treatment, is heat-treated.

Thermal treatment remains on for the brilliant boat of the thermal treatment that wafer will be installed transfers load in argon environment, in 700 ℃ of stoves, be warming up to 1000 ℃ with 5 ℃/minute slow speed.After 1000 ℃ with 2 ℃ of/minute intensifications, 1200 ℃ of thermal treatments 1 hour.Subsequently, be cooled to 1000 ℃ with 2 ℃/minute, with 4 ℃ of/minute coolings, in the time of 700 ℃, take out the brilliant boat (wafer) of thermal treatment below 1000 ℃ from heat treatment furnace.

Needed time of annealing is about 6.5 hours.

From resulting annealing wafer like this, extract 3 out, confirm DZ layer and bmd density.As a result, the DZ width is that average 10.4 microns, bmd density are average 5 * 10 ⁹Individual/cm ³Degree.

Again, a situation arises to confirm the slip transposition of these wafers with X line Photographic technique (XRT).Do not observed the slip transposition.

3 of wafers after the thermal treatment are measured the heavy metal degree of crystal column surface.The heavy metal degree is Fe:1 * 10 ⁹Atoms/cm ², Cu:9 * 10 ⁸Atoms/cm ², Ni:8 * 10 ⁸Atoms/cm ², the metallic pollution degree is low, and by shortening the heat treatment time under the wafer state, crystal column surface can keep lower metallic pollution.

(comparative example 2)

Behind the wafer state that becomes in the past, carry out forming the manufacture method of the annealing wafer of DZ layer and BMD by thermal treatment.

Wafer is the wafer via 300 millimeters of the diameters of the same wafer procedure of processing of embodiment 3.Oxygen concn or nitrogen concentration are also identical with embodiment 3.

Wafer be annealed into will be equipped with the brilliant boat of thermal treatment of wafer transfer load to and remain in argon environment, in 500 ℃ of stoves, be warming up to 1000 ℃ with 1 ℃/minute very slow speed and heat-treat, form BMD fully.Subsequently with 2 ℃ of/minute intensifications, in order to form the DZ layer 1200 ℃ of thermal treatments 1 hour.Subsequently, be cooled to 1000 ℃ with 2 ℃/minute, with 4 ℃ of/minute coolings, in the time of 700 ℃, take out the brilliant boat (wafer) of thermal treatment below 1000 ℃ from heat treatment furnace.

Needed time of annealing is about 14 hours.

From resulting annealing wafer like this, confirm DZ layer and bmd density.As a result, the DZ width is that average 9.5 microns, bmd density are average 2 * 10 ⁹Individual/cm ³Degree.

By condition like this, though can obtain the wafer quality of same level almost, need the heat treatment time of quite long wafer with embodiment 3, productivity is poor.Again, the heavy metal degree of crystal column surface is Fe:5 * 10 ⁹Atoms/cm ², Cu:1 * 10 ¹⁰Atoms/cm ², Ni:1 * 10 ⁹Atoms/cm ², the metallic pollution degree is poorer than embodiment 3.

The present invention can carry out the good thermal treatment of efficient and form BMD by in the annealing of silicon wafer ingot, adds and can shorten the wafer annealing time significantly, and when implementing with above-mentioned condition, the wafer heat treatment time can foreshorten to 6.5 hours from the past about 14 hours.By this, can promote productivity significantly.

(embodiment 4)

(cultivation of silicon wafer ingot)

(silicon wafer ingot annealing: heat treatment step)

To above-mentioned silicon wafer ingot, heat-treat with the state former state of silicon wafer ingot.At first, use by HF/HNO ³The acidic etching liquid that is constituted carries out about 200 microns etchings, removes the metal impurity of contaminated surface.

Thermal treatment is from room temperature to 500 ℃, with 10 ℃ of/minute intensifications of heat-up rate, subsequently, is warming up to 800 ℃ with about 1 ℃/minute, keeps 4 hours at 800 ℃.Subsequently, be cooled to 600 ℃, subsequently, with about 2 ℃/minute, be cooled to room temperature with about 5 ℃/minute cooling rates.What the environment during this thermal treatment used is oxygen.

By this, can make wafer in large quantities by implementing thermal treatment once as Jingjing physa plate of heap of stone.

(wafer procedure of processing)

The wafer procedure of processing is that step is handled as shown in Figure 8.Slicing step ((A) among Fig. 8) uses scroll saw to cut off, after the oblique angle procedure of processing ((B) among Fig. 8), planarisation step ((C) among Fig. 8) uses the above free abrasive grain of #1500 to polish, ((D) among Fig. 8, the alkaline solution of working concentration 50%NaOH carries out etching at etching step.Grinding steps subsequently ((E) among Fig. 8) obtains the wafer of high flat degree and mirror-polishing for carrying out 3 sections grindings that grind on the two sides, one side is ground, one side is ground.Subsequently, carry out after scouring.Can obtain the Silicon Wafer of 300 millimeters of about 300 diameters from above-mentioned 30 centimeters silicon wafer ingot.

(building crystal to grow)

Use of heap of stone brilliant device shown in Figure 11 on this wafer, to form epitaxial layer.At first, wafer is carried out pre-treatment.This wafer is positioned in is maintained in 23 ℃, 1 atmospheric treatment chamber, at first be 100 liters/minute and supply with and use H with flow ₂The 1%HF mixed gas that gas dilution forms 3 minutes is removed the natural oxide film of this crystal column surface.Then, the resistance heading furnace energising to the peripheral part that is arranged on treatment chamber makes the temperature of wafer be warming up to 1000 ℃.During temperature stabilization, feed with H for 100 liters/minute with flow ₂The 1%HCL mixed gas that gas dilution forms 1 minute is removed organic film.

Then, carry out building crystal to grow.Make and be H in the treatment chamber ₂Atmosphere surrounding is adjusted the energising amount of the infrared(ray)lamp be arranged on top, makes the temperature of wafer be warming up to 1100 ℃, behind the temperature stabilization, at once with the H that passes through of 100 liters/minute of flows ₂The 2%SiHCl that dilution forms ₃The mixed gas and the B of injector trace together ₂H ₆One minute.Obtaining by this growing up, thickness is arranged is that 3 microns, resistivity are that 15 Ω .cm, boron concentration are 1 * 10 ¹⁵/ cm ³The Jingjing of heap of stone circle of silicon single crystal film (epitaxial layer).

Confirm the bmd density of the substrate-side of the Jingjing circle of heap of stone that arrives like this.Bmd density is with 1000 ℃ of thermal treatments obviousization of BMD to be measured.The result who uses the infrared photography method to estimate obtains about 6 * 10 ⁹Atoms/cm ³High bmd density.Therefore, obtain by the inventive method, only Guan Wei carries out the thermal treatment of pyritous building crystal to grow, can also make the Jingjing circle of heap of stone that is formed with many BMD (can become suction location).

These wafers are carried out the observation of epitaxial layer defective again.Do not observe the epitaxial layer defective.

(comparative example 3)

Except silicon single crystal not being heat-treated, use usual method to make Jingjing circle of heap of stone in the silicon wafer ingot stage.Oxygen concn or nitrogen concentration carry out on sample ground mutually with embodiment, form silicon single crystal silicon wafer ingot after, carry out the same wafer procedure of processing of embodiment 4, make the wafer of 300 millimeters of about 300 diameters.Then, with the same building crystal to grow condition of embodiment 4, on wafer, form epitaxial layer.

With embodiment 4 similarly, confirm the bmd density of the substrate-side of the Jingjing of heap of stone circle that arrives like this.As a result, bmd density is average 1 * 10 ⁸Atoms/cm ³So, when annealing in the silicon wafer ingot stage, bmd density is a lot of less.Therefore, in order to obtain gettering ability fully, must be in its after-applied long thermal treatment, in order on wafer, to form BMD.

Again, the present invention does not limit above-mentioned example.Above-mentioned example only is exemplary, with the technological thought and the identical in fact formation of claims of the present invention record, reach the thing of same purpose effect, in any case be included in the technical scope of the present invention.

For example, the foregoing description is that the silicon wafer ingot is divided into plural silicon wafer piece, carries out the annealing of silicon wafer ingot with the state of silicon wafer piece, but can also not carry out this kind cut-out and handle with the silicon wafer ingot former state of pull-up state.When so carrying out, can the primary treatment few silicon wafer ingot that pollutes etc.

Claims

1. the manufacture method of a wafer, contain following step at least: silicon wafer ingot heat treatment step, the silicon single crystal that is doped with nitrogen of silicon wafer ingot state is heat-treated; And the wafer procedure of processing, the silicon wafer ingot that this is heat treated is processed into wafer.

2. the method for claim 1, wherein this silicon wafer ingot heat treatment step is to form inner tiny flaw at this silicon single crystal.

3. the method for claim 1 wherein after this wafer procedure of processing, has the wafer heat treatment step that this wafer is heat-treated.

4. method as claimed in claim 2 wherein after this wafer procedure of processing, has the wafer heat treatment step that this wafer is heat-treated.

5. as any described method in the claim 1 to 4, wherein after this wafer procedure of processing, silicon wafer ingot that can this is heat treated is processed into the wafer of mirror-like.

6. method as claimed in claim 5 wherein after being processed into the wafer of mirror-like, has the building crystal to grow step that forms epitaxial layer on this wafer.

7. the method for claim 1, this silicon wafer ingot heat treatment step wherein is that silicon single crystal to silicon wafer ingot state carries out the thermal treatment more than 700 ℃.

8. method as claimed in claim 7, wherein this silicon wafer ingot heat treatment step is to carry out more than 30 minutes 8 hours with interior thermal treatment in the thermal treatment temp below 1100 ℃.

9. method as claimed in claim 8, wherein this silicon wafer ingot heat treatment step is to carry out more than 30 minutes 8 hours with interior thermal treatment in the thermal treatment temp below 900 ℃ more than 700 ℃.

10. the method for claim 1, wherein make this silicon wafer ingot heat treatment step heat-up rate be 0.5 ℃/minute～10 ℃/minute and heat-treat.

11. as claim 3 or 4 described methods, wherein this wafer heat treatment step is to form nondefective zone at this crystal column surface.

12. as claim 3 or 4 described methods, wherein this wafer heat treatment step is more than 900 ℃ below 1300 ℃, carries out more than 5 minutes 16 hours with interior thermal treatment.

13. as claim 3 or 4 described methods, wherein this wafer heat treatment step is that heat-up rate is being heated up more than 5 ℃/minute.

14. method as claimed in claim 6, wherein this building crystal to grow step is after the temperature more than 1000 ℃ is carried out pre-treatment, carries out building crystal to grow with the temperature more than 1000 ℃.

15. as any described method of claim 1 to 4, wherein this silicon single crystal is the crystallization of the quasi-full crystallizing field that forms of the manufacturing by Czochralski method.

16. as any described method of claim 1 to 4, the silicon single crystal of this silicon wafer ingot state wherein is to use the silicon wafer ingot that cuts into the cylindric silicon wafer bulk state of crossing through skiving after the silicon wafer ingot of single crystal pull-up device pull-up state former state shape or the pull-up by Czochralski method.