CN101002308A - Method and equipment for forming oxide film - Google Patents

Abstract

Oxide film forming equipment is provided with a reactor (10) wherein a heater unit (14) holding a substrate (100) is stored; a piping (11) provided with a material gas introducing valve (V1) for introducing a material gas containing organic silicon or organic metal into the reactor (10); a piping (12) provided with an ozone containing gas introducing valve (V2) for introducing an ozone containing gas into the reactor (10); and a piping (13) provided with an exhaustion valve (V3) for exhausting a gas in the reactor (10). When the material gas introducing valve (V1), the ozone containing gas introducing valve (V2) and the exhaustion valve (V3) perform opening/closing operation so as to alternately supply the material gas and the ozone containing gas into the reactor (10), the ozone containing gas introducing valve (V2) operates so as to have the ozone concentration of the ozone containing gas at 0.1-100 vol.%, and a heater unit (14) adjusts the temperature of the substrate (100) within a range of a room temperature to 400 DEG C.

Description

Be used to form the method and apparatus of oxidation film

Technical field

[0001] the present invention relates to prepare at low temperatures the technology of high-quality dielectric film, described dielectric film is such as thin-film transistor (TFT), the core of devices such as silicon device on organic substrate, and this device is because the heat resisting temperature of base material temperature and processing temperature is limited to some extent.

Background technology

[0002] in recent years, the LCD device of TFT system has been widely used as display device.The LCD device has glass baseplate, and TFT on this base material (thin-film transistor) forms matrix form, and this TFT drives the liquid crystal that is in the TFT vertical direction.TFT is film formed by the dielectric film or the polysilicon that are laminated on the glass baseplate.As glass baseplate, used the soda-lime glass cheap than quartz glass.Soda-lime glass is compared with quartz glass has about 500 ℃ low softening point.In addition, contained sodium can diffusion under hot environment in the soda-lime glass.Therefore, need be 400 ℃ or the film technique under the low temperature more.In addition, require the film quality of the film that forms like this to have the approaching high-quality of film quality with formed film under higher temperature.And, in recent years, be representative with flexible information terminal (flexible PC, portable phone), the technology that goes up the preparation silicon device at organic (flexibility) base material such as plastics (polyimides) etc. becomes very important.In this case, from the heat resisting temperature of polyimides etc., technological temperature is 250 ℃ or lower.

[0003], mainly uses silicon dioxide film for these dielectric films.Film build method mainly comprises such technology, wherein SiO ₂Film is deposited on by hot CVD or plasma CVD method and goes up on the polysilicon (for example, film thickness is 50nm) of preparation at glass (or organic material).Under the situation of using hot CVD, mainly use SiH ₄+ O ₂But, notice like this and can bring many problems that for example contain a large amount of impurity or moisture at 300 ℃ or the dielectric film that more prepares under the low temperature, tightness is low, has many apertures and particle, and has low insulation withstand voltage and high leakage current.

[0004] thereby, in order to address these problems, use the plasma CVD method.For example, according to non-patent literature 1 (J.Vac.Sci.Technol.A21,728 (2003)), use SiH ₄+ O ₂Gas has successfully been prepared such dielectric film by CVD in ECR (electron cyclotron resonace) plasma reaction heating furnace, it is under 100 ℃ base material temperature, have the high-quality insulation withstand voltage of 4MV/cm, interface level (interfa celevel) density is 10 ¹²[eV ^-1Cm ^-2], and stable state charge density is 10 ¹¹[cm ^-2].

[0005] still, if use the plasma CVD method, following problem can appear.Owing to be the reaction of gas phase ionic medium body, find many particles, step coverage rate is low, is the film density (2.2g/cm that realizes ideal ³) and form that (Si: O=1: 2) required process window (film-forming temperature, gas pressure, and electrode of opposite spacing etc.) is narrow.Because the existence of many particles must usually purify film forming room.

[0006] in order to alleviate problem mentioned above, as the reacting gas that can use high safety, can set membrance casting condition at an easy rate, and can suppress described granuloplastic film build method at an easy rate, someone has proposed hot CVD technology, and this technology is comprising that the organosilicon material with Si-O key and Si-H key is (than SiH ₄More easy to operate) with the mist of ozone under carry out.Utilized the oxidability of ozone gas to the height of organic substance.

[0007] according to patent documentation 1 (Japanese Laid-Open Patent Application (tokkai) No.Heisei8-31815), successfully obtained the SiO that has the deposition of good step coverage rate at 400 ℃ ₂Film, this is owing under atmospheric pressure use TMS (trimethoxy silane), TES (triethoxysilane), TEOS (positive tetraethyl orthosilicate) and ozone gas carry out hot CVD.Notice that ozone is a kind of like this gas, it can carry out the quality that thermal decomposition and certain density ozone gas can influence film widely.Therefore, by using nitrogen to be diluted to enough low concentration (ozone gas can stably exist under this concentration) as carrier gas and with ozone gas, can realize the effective supply of ozone gas, at the uniform deposition that carries out CVD reaction and realization film near the substrate surface place equably.

[0008] on the other hand, (Japanese Laid-Open Patent Application (tokkai) No.Heisei 5-259155) is known according to patent documentation 2, when the concentration of use ozone gas becomes higher, be present in the impurity in the film such as the concentration of hydro carbons and can become lower, thereby anti-moisture-absorption characteristics becomes favourable, it is favourable that insulation characterisitic becomes, and leakage current diminishes.That is, using under the situation of ozone gas, between the high-quality of the uniformity (film thickness and film quality) of cvd film and film, having equilibrium relation.Although utilized the high oxidative capacity of ozone gas, still can't realize the technology of wherein using high-concentrated ozone gas that reaction rate is controlled to organic substance.

[0009] in addition, in being equal to or less than 300 ℃ low temperature process, even use the CVD that contains ozone gas, still can not definitely eliminate owing to organic substance gas in the gas phase enters the pollution that brings in the film by C series organic substance and the water (and hydrogen or OH) that the accessory substance that is decomposed to form causes.For example, as what reported in the non-patent literature 2 (J.Vac.Sci.Technol.B8,533 (1990)), the film of deposition is a porous, this can be confirmed by the following fact, and promptly the film after the deposition demonstrates in hydrofluoric acid cushioning liquid than fast ten times of thermal oxide film or etch-rate faster.If after deposition, carry out RTA (rapid thermal annealing), then can obtain highdensity film (showing as the reduction of film etch-rate).But, must be at about 1000 ℃ of following heating films to obtain density film near thermal oxide film.Such heat technology can not be used for aforesaid film-forming process on glass or organic substrate.

Non-patent literature 1:J.Vac.Sci.Technol.A21,728 (2003)

Patent documentation 1: Japanese Laid-Open Patent Application No.Heisei 8-31815

Patent documentation 2: Japanese Laid-Open Patent Application No.Heisei 5-259155

Non-patent literature 2:J.Vac.Sci.Technol.B8,533 (1990)

Summary of the invention

[0010] considers the above situation, purpose of the present invention provides the method and apparatus that forms oxidation film, it can prepare even and high-quality dielectric film, effectively utilize simultaneously high-concentrated ozone gas to the capacity of decomposition of organic substance and, particularly, can be only prepare high-quality dielectric film by the low temperature process that is equal to or less than 300 ℃.

[0011] method and apparatus according to formation oxidation film of the present invention can form high-quality silicon dioxide film (SiO to cause the CVD reaction thereon by alternately containing organosilicon or organometallic unstrpped gas and contain ozone gas to the base material supply ₂And even can be only be equal to or less than the high-quality dielectric film of preparation under 300 ℃ the low temperature film).

[0012] method according to formation oxidation film of the present invention is the silicon dioxide film film build method, wherein, on substrate surface, form silicon dioxide film by alternately comprising the organosilicon of (silicon)-O (oxygen) key that has Si or Si (silicon)-C (carbon) key or have the organometallic unstrpped gas of metallic element-oxygen key or metallic element-carbon bond and contain ozone gas to the base material supply.In the method, regulate base material temperature in the scope of room temperature to 400 ℃, and regulate and contain the ozone concentration of ozone gas in the scope of 0.1 volume % to 100 volume %.

[0013] in addition, according to oxidation film forming device of the present invention, wherein alternately contain the organosilicon of (silicon)-O (oxygen) key that has Si or Si (silicon)-C (carbon) key or have the organometallic unstrpped gas of metallic element-oxygen key or metallic element-carbon bond and contain ozone gas to the base material supply, on substrate surface, to form oxidation film, comprise: a reactor, design this reactor with the unit heater that is used to hold base material of packing into; One is equipped with the pipeline that is used for unstrpped gas is introduced the unstrpped gas introducing valve of reactor; Another is equipped with and is used for introducing the pipeline that ozone gas is introduced valve that contains of reactor with containing ozone gas; And another is equipped with the pipeline that is used for the vent valve of the discharge of the gas in the reactor, when unstrpped gas introduce valve, contain that ozone gas is introduced valve and vent valve is opened-shutoff operation is with unstrpped gas with when containing ozone gas and alternately being supplied in the reactor, contain ozone gas and introduce the ozone concentration that valve will contain ozone gas and be adjusted to 0.1 volume % in 100 volume % scopes, and unit heater is adjusted to base material temperature in room temperature to the 400 ℃ scope.

[0014] in the method for above-mentioned formation oxidation film, can control unstrpped gas introduces the opening of valve and vent valve-shutoff operation and is alternately supplying raw material gas and containing in the circulation of ozone gas so that make, comprise in unstrpped gas under the situation of a silicon atom, the introducing pressure of unstrpped gas is in the scope of 0.1Pa to 100Pa, and comprise in unstrpped gas under the situation of n silicon atom, the introducing pressure of unstrpped gas can have a upper limit, and it is the 1/n of above-mentioned pressure limit.

[0015] at this moment, in above-mentioned oxidation film forming device, for example, can control unstrpped gas introduces the opening of valve and vent valve-shutoff operation and is alternately supplying raw material gas and containing in the circulation of ozone gas so that make, comprise in unstrpped gas under the situation of a silicon atom, the introducing pressure of unstrpped gas is in the scope of 0.1Pa to 100Pa, and comprise in unstrpped gas under the situation of n silicon atom, the introducing pressure of unstrpped gas can have a upper limit, and it is the 1/n of above-mentioned pressure limit.

[0016] in addition, in the method for above-mentioned formation oxidation film, can in unstrpped gas, supply and contain ozone gas being included in stoichiometric supply that organosilicon in the unstrpped gas or organic metal all be oxidized to silicon dioxide or metal oxide at least being equivalent to.At this moment, in above-mentioned oxidation film forming device, can control ozone gas and introduce the opening of valve-shutoff operation and contain ozone gas with supply, its supply is equivalent to and will be included in the chemical equivalent that organosilicon in the unstrpped gas all is oxidized to silicon dioxide at least.

[0017] more specifically, in the method for above-mentioned formation oxidation film, the supply that contains ozone gas can be set at the amount that reaches following degree: supplied contain ozone gas after, raise and can determine owing to being present in base material, unstrpped gas and containing the pressure that the thermal decomposition of the ozone in the capping system of ozone gas causes.At this moment, in above-mentioned oxidation film forming device, for example, can control and contain opening-shutoff operation of ozone gas introducing valve, be set at the amount that reaches following degree so that contain the supply of ozone gas: supplied contain ozone gas after, raise and can determine owing to being present in base material, unstrpped gas and containing the pressure that the thermal decomposition of the ozone in the capping system of ozone gas causes.

[0018] in other words, the exposed amount that contains ozone gas of introducing can be set at such ratio, is about to estimate the organosilicon in chemical equation or organic metal oxidation formation silicon dioxide or metal oxide at least, thereby is oxidized to CO all ₂And H ₂The ratio that O is required.Ideal situation is that the supply that contains ozone gas should make, after supply contains ozone gas, is under the situation of closed system in reaction system, can determine because the pressure that extra ozone thermal decomposition causes after the reaction raises.

[0019] in addition, in the method for above-mentioned formation oxidation film, alternately supply raw material gas and contain ozone gas each the circulation in, the film forming speed of each circulation reduces with the reduction of base material temperature.At this moment, in above-mentioned oxidation film forming device, for example, alternately supplying raw material gas and containing in each circulation of ozone gas, can control unstrpped gas introduce valve, contain that ozone gas is introduced the opening of valve and vent valve-shutoff operation so that in each circulation film forming speed reduce with the reduction of base material temperature.

[0020] in the method and apparatus that forms oxidation film, base material temperature is under 200 ℃, and film forming speed can be in 0.2nm/ be circulated to the 1.0nm/ range of DO.In addition, base material temperature is under 300 ℃, and film forming speed can be in 0.2nm/ be circulated to the 5.0nm/ range of DO.Notice, and will be as described in hereinafter, in the process of using ultraviolet light, film forming speed can be increased to the value that is equal to or higher than following situation, promptly when base material temperature is instantaneous when bringing up to the base material temperature value that only is equal to or higher than when just applying instantaneous heating in supply ozone process those values.But film forming speed depends on the brightness and the transient temperature of ultraviolet light.

[0021] in addition, in the method for above-mentioned formation oxidation film, ultraviolet light can alternately supply raw material gas and being radiated on the base material when containing ozone gas.

[0022] at this moment, in above-mentioned oxidation film forming device, reactor can, for example, the light source and the UV-irradiation window that are used for the UV-irradiation base material are housed, the ultraviolet light of irradiation is by the transmission of this window.Transmit if ultraviolet light passes described window, then the material of UV-irradiation window can be known material.

[0023] in addition, in the method for above-mentioned formation oxidation film, a reactor can be provided, in this reactor, by alternately supplying raw material gas and contain ozone gas and form oxidation film with the UV-irradiation base material on substrate surface simultaneously, the distance between the UV-irradiation window that base material is installed to the reactor can be adjusted to the absorption degree of depth (this distance is equivalent to the 1/e of incident intensity) that the ultraviolet light that is shorter than introducing is absorbed by ozone partial pressure.

[0024] at this moment, in the oxidation film forming device, unit heater can at random be adjusted to the position that may place base material, and unit heater is used to regulate the position of base material so that the distance of UV-irradiation light window and base material is shorter than the absorption degree of depth (this distance is equivalent to the 1/e of incident intensity) that the ultraviolet light of introducing is absorbed by ozone partial pressure.Unit heater can be the known unit heater that can at random regulate substrate location.

[0025] in addition, can adopt low pressure cold-wall type reactor or hot wall type reactor as the reactor in the method and apparatus that is used to form oxidation film mentioned above.

[0026] in addition, because, in the method and apparatus according to formation oxidation film of the present invention mentioned above, contain ozone gas and unstrpped gas is not supplied simultaneously, be such type promptly because of method and apparatus according to formation oxidation film of the present invention, promptly wherein containing ozone gas is introduced in the unstrpped gas that is present in the utmost point low-pressure (molecular density) in the reactor, the high-concentrated ozone gas that organic substance is had a high reactivity (for example, 100% ozone) can be used as oxidant, and need not to consider its danger as oxidant.

[0027] and, because unstrpped gas filled equably the space and, afterwards, fill abundant amount be enough to complete oxidation unstrpped gas contain ozone gas in a large number, therefore, can realize that the high uniformity of large scale base material is handled.Though,,, then can't avoid fluctuation (because of the space wave of unstrpped gas and ozone gas molecular density) in the VISCOUS FLOW pressure span by the caused steric course of air-flow if technology is carried out handling in the situation of base material by flowing gas.But aforesaid problem does not exist in the method and apparatus of formation oxidation film according to the present invention.

[0028] in addition, among the present invention alternate supplies unstrpped gas and contain the method for ozone gas and ALD (ald) method (ALD is such method, wherein pass through gas supply subsequently, transform being adsorbed on lip-deep molecular raw material gas, deposit the film of an atomic layer, and this step cycle ground repeats) to compare, the film that each circulation is deposited is thicker, and the ALD method is an important techniques in film in recent years, is the control method and the large-area deposition process of height.Therefore,, and can reduce the film forming required time, improve disposal ability for the required number of times that repeats to supply of the oxidation film that is fixed film thickness is minimized.Particularly, alternately supplying raw material gas and when containing ozone gas, use the UV-irradiation base material.Like this, just can realize film forming speed quickly in each circulation.

[0029] in addition, have high reactivity because contain ozone gas, therefore, with the H that up to the present in ALD technology, is used as oxidant sometimes ₂O compares, and has shortened the process time of each circulation.That is to say that because used ozone as dry gas, the steam of staying the water in the reactor when reaction finishes forces down, and be difficult to can not rest in the reactor by the gas that dry pump is discharged, faster thereby bleeding can become.

[0030] in addition, because the utilization ratio of ozone gas improves and the use amount of ozone gas reduces, to the load reduction of gas extraction system.In the production of ozone gas, main usually use high frequency electric source discharges.With regard to carrying capacity of environment, (need electric power in the production of ozone gas), wish to use less ozone gas as far as possible.Satisfied above-mentioned viewpoint according to silicon dioxide film build method of the present invention and equipment.

[0031] in addition, in the method and apparatus according to formation oxidation film of the present invention, base material temperature is set to room temperature when supplying raw material gas, and processing temperature by pulsed be set at the supply of ozone gas and conform to opportunity.Like this, just can make the reaction system temperature inside constant in room temperature.Realize easily uniformly (unstrpped gas and contain ozone gas) CONCENTRATION DISTRIBUTION, thereby can realize uniform processing.In this case, compare with the situation that base material is wherein heated continuously, high temperature can instantaneously be applied on the base material.Like this, not only improved the diffusion length (that is, can improve the film thickness that each circulation forms) of ozone, and, hydrogen and the water system impurity stayed easily in the oxidation film also can be eliminated effectively.

[0032] therefore, according to the method and apparatus of formation oxidation film of the present invention, when bringing into play the organic substance capacity of decomposition of high-concentrated ozone gas effectively, can prepare even and high-quality dielectric film.Therefore, only just can prepare high-quality dielectric film by the low temperature process that is equal to or less than 300 ℃.

[0033] in addition, in the method and apparatus of formation oxidation film according to the present invention, when base material is under the situation about making with the polysilicon series raw material, to base material alternate supplies unstrpped gas with contain ozone gas with before forming thermal oxide film on the base material, contain ozone gas can with constant flow supply and under constant base material temperature to the constant time of base material supply.Like this, even at low temperatures, also can grow into the thermal oxide film of more even and high-quality (high density) with density film thickness.That is to say, make the surface state of base material can obtain more uniform control thereby carry out the ozone thermal oxidation.

[0034] in addition, if UV-irradiation is on base material when forming thermal oxide film,, also can form (for example, more high-quality thermal oxide film 3nm) that has enough film thicknesses at short notice even under low temperature (for example, room temperature).

[0035] as mentioned above, can prepare even and high-quality dielectric film, particularly, can be only in being equal to or less than 300 ℃ low temperature process, form high-quality dielectric film according to the method and apparatus of formation oxidation film of the present invention.

The accompanying drawing summary

[0036] Fig. 1 is the schematic structure view of expression first preferred embodiment according to the present invention.

Fig. 2 is the process chart relevant with first preferred embodiment.

Fig. 3 is the characteristic pattern in ozone gas life-span in the expression gas phase.

Fig. 4 is the gas composition figure after introducing 2700Pa ozone gas and 2700Pa oxygen under the TEOS 300Pa air pressure.

Fig. 5 is the gas composition figure after introducing 2700Pa ozone gas and 2700Pa oxygen under the TMS 300Pa air pressure.

Fig. 6 is the characteristic pattern of expression admixture of gas ratio effect, represents particularly that with regard to the mass number 193 that is equivalent to raw material TEOS gas flow the ozone gas of the ozone gas of each mass number signal strength signal intensity is introduced correlation.

Fig. 7 is the figure of representation feature film forming speed.

Fig. 8 is the figure of representation feature FTIR spectrum.

Fig. 9 is the figure of expression electric field strength vs. leakage current density.

Figure 10 is the schematic structure view of expression second preferred embodiment according to the present invention.

Figure 11 is and the relevant process chart of the present invention's the 3rd preferred embodiment.

Implement best mode of the present invention

[0037] describes according to the preferred embodiments of the invention below with reference to accompanying drawing.

[0038] (first embodiment)

Fig. 1 is the topology view sketch of oxidation film forming device in first preferred embodiment.In addition, Fig. 2 illustrates the technological process relevant with first preferred embodiment.

[0039] in this embodiment, oxidation film forming device 1 comprises: reactor 10, wherein be equipped with the unit heater 14 that is used to hold base material 100; Pipeline 11 wherein is equipped with the unstrpped gas introducing valve V1 that is used for unstrpped gas is incorporated into reactor 10 inside; Pipeline 12 wherein is equipped with and is used for introducing valve V2 with containing the ozone gas that contains that ozone gas is incorporated into reactor 10 inside; With pipeline 13, the vent valve V3 that is used for the waste gas discharge of reactor 10 inside is housed wherein.Then, control unstrpped gas is introduced valve V1, is contained opening-shutoff operation of ozone gas introducing valve V2 and vent valve V3.Thus, on the surface of base material 100, form silicon dioxide film with containing ozone gas by the gas that alternately supplies raw material in reactor 10 inside.

[0040] as reactor 10, only can adopt can heated substrate 100 low pressure (employing reacting furnace) cold-wall type reactor.The exhaust pump (not shown) is connected on the pipeline 13, is used for only heated substrate 100.In addition, the installation form of base material 100 can adopt known longitudinal type or lateral type in the reactor 10.The material that is noted that reactor 10 can adopt the material that does not have reactivity for ozone.For example, can exemplify quartz, stainless steel, aluminium, titanium or the like.

[0041] unstrpped gas can be the organic substance with Si-C key or Si-O key.For example, TEOS (positive tetraethyl orthosilicate), HMDS (hexamethyldisiloxane (hexamethyldislazane) or the like.

[0042] heat the system of the hot device 141 of the life that is to use as shown in Figure 1 by 14 pairs of base materials 100 of unit heater, wherein base material 100 places bringing-up section 140.In addition, can adopt general well-known heating means, wherein be radiated on the INFRARED ABSORPTION section of holding described base material (for example, making) by sintered sic with Halogen lamp LED to the heating of base material 100.

[0043] for the exhaust of reactor 10 inside, can directly use the system that is used on traditional CVD stove.At this moment, need to discharge the device of harmful components, be equal to or less than the dry pump of about 1Pa as particle trap and final vacuum, for example, mechanical booster pump (for example, deflation rate is 1000 liters/minute).

[00441] Fig. 2 shows the technological process that forms silicon dioxide film.

[0045] this flow process that illustrates comprises the step of a circulation (for example, 1-10 second): (1) fills the pressure in unstrpped gas (2) the conditioned reaction device, and (3) introduce ozone gas, pressure in (4) conditioned reaction device and the exhaust in (5) gas reactor.Each valve (V1, V2 and V3) opened-shutoff operation (O: open C: close) during Fig. 2 showed and respectively goes on foot.Be noted that in Fig. 2 (P ₀) refer to back pressure (for example, 1Pa), (P ₁) refer to unstrpped gas stuffing pressure, (P ₂) guide the pressure behind the ozone.

[0046] the following summary that will explain the above-mentioned opening-shutoff operation of each valve.

[0047] 1) at first, opens valve (V1) gas that supplies raw material, thereby make unstrpped gas (for example, be filled into the inside of reactor 10 under 10Pa) in the constant voltage that is higher than exhaust-gas limits pressure.

[0048] 2) in this case, because according to unstrpped gas, the vapour pressure height (for example under the room temperature (cold wall temperature and the gas phase temperature that is enough to away from the area of heating surface), under the situation of TMS (tetramethylsilane), at 20 ℃ is 600 holders), so the pressure that exhaust will proceed in the reactor becomes till the above-mentioned pressure.At this moment, the introducing of unstrpped gas can realize (in addition, can adopt vertical heater or horizontal chamber furnace (oven)) by introducing from the side of reactor or above the shower nozzle of reactor.On the contrary, (for example, in the time of 10Pa), the temperature of OMTS (octamethylcy-clotetrasiloxane), supply line system and whole reactor is heated to and it be become equal the degree of the blowing pressure when the vapour pressure of unstrpped gas is lower than the blowing pressure.The life-span of ozone that is equal to or less than 100 ℃ is long as described as follows, thereby being enough to make to adopt hot wall type heating furnace (electric furnace).

[0049] 3) next, will contain ozone gas is incorporated in system's (process reactor 10).The constant flow rate that is introduced in that contains ozone gas is as carrying out under the constant mass flow.Perhaps, can adjuster valve (V2) open-shutoff operation is so that raise to become steady state value the pressure in the system.At this moment, as required, introduce on the valve (V2) soft start function is provided containing ozone gas, thereby can prevent that unexpected gas from introducing or the particle that accompanies forms and prevent that particle contamination is in silicon dioxide film.In addition, by the physical distance of maintenance, can avoid powder impurity to enter into base material 100 with wall.

[0050] the ozone concentration scope that contains ozone gas is 0.1% to 100%.Can use the gas by the manufacturing of general industrial ozone generator and from this oxygen-ozone gas mixture, remove the high-concentrated ozone of oxygen.

[0051] according to the difference of the Organic Ingredients gas that uses, it is different that required ozone is introduced dividing potential drop.Usually, unstrpped gas is oxidized to CO fully ₂And H ₂O.In addition, the silicon amount of filling is equal to or greater than by extra oxygen atom conversion silicon and enters into desirable oxidation state (SiO ₂) required quantity.For example, when such as use TEOS gas, as understanding, under 8 times TEOS pressure (an amount of material), prepared the wherein complete oxidized film of silicon from following chemical formula.Simultaneously, organic substance can be with CO from the substrate surface deposited film ₂And H ₂The form of O is discharged.Equally, under the situation of TMS, can accept 5.33 times pressure.

[0052] under the situation of TEOS:

Si(OC ₂H ₅) ₄+8O ₃→SiO ₂+8CO ₂+10H ₂O

Under the situation of TMS:

3Si(CH ₃) ₄+16O ₃→3SiO ₂+12CO ₂+18H ₂O

But, note, when base material temperature is equal to or higher than room temperature, for example, when being 300 ℃, because before ozone arrives at substrate surface, owing to feeling that from base material thermal decomposition takes place in thermal radiation, therefore, owing to causing the CVD in the gas phase, the reaction of the CVD on substrate surface reacts (promotion of surface reaction has allowed the correlation of base-material), thereby make that projection and pocket portion appear in raw material quality and the surface state because of base-material on the surface profile of the film that increases, and eliminated the variation (referring to Japanese Laid-Open Patent Application (tokkai) No.Heisei8-031814) of layer-growth rate, in this case, must introduce the ozone gas that quantity is equal to or greater than above-mentioned amount.The life-span of ozone gas is to calculate with the pyrolysis velocity constant of ozone in the gas phase.

[0053] Fig. 3 shows the characteristic pattern in ozone gas life-span in the expression gas phase.Temperature is the life-span (gas temperature is 300 ℃ zone) of the inner ozone of boundary layer on 300 ℃ the surface of base material, depress in 0.01 atmospheric pressure and 100 volume % ozone gas and to be shown as 0.1 second, under 1 atmospheric pressure and 1 volume % ozone air pressure (99 volume % oxygen), be shown as 0.01 second.In this way, ozone gas is than containing thermal decomposition under the time that ozone gas is filled into the filling time shorter (being 1 second or 10 seconds typically) in the reactor.That is to say that ozone gas does not arrive substrate surface, and transmission becomes the speed control factor.

[0054] when the ozone gas in the gas phase near substrate surface the locational life-span than time of ozone gas body source in short-term (for example, using 100% concentration of ozone gas to make that system pressure is 0.1 atmospheric pressure, base material temperature be 250 ℃ or when higher), must be introduced in the extra ozone gas outside the above-mentioned ozone gas.Abundant or the insufficient basis possibly of amount that contains ozone gas, whether the pressure when after the supply of ozone gas finishes heating furnace being sealed in the reactor raises and decides.That is to say, as shown in Figure 2, if organosilicon gas with contain after ozone gas reacts, have extra ozone, so because the thermal decomposition meeting of ozone gas on the high temperature substrate surface raises pressure.

[0055] Supply Method for ozone gas does not have special restriction.Perhaps adopt vertical stream,, perhaps adopt horizontal method of supplying from the top inflow of the base material on shower nozzle, with the direction supply parallel with base material, this dual mode all is an acceptable, and condition is, compare with the quantity that is used for the unstrpped gas reaction, it is enough that the ozone gas dividing potential drop is wanted.Under the uneven situation of film, be used for method in routine, can or use as improving the inhomogeneity mechanism of cvd film on the basis that base material is rotated with vertical stream, perhaps use with the level supply.

[0056] the following mass spectrum that will use is estimated the reactivity of material gas of gas phase Central Plains under the room temperature and ozone gas and needed ozone gas amount for the unstripped gas scale of construction.

[0057] (experimental technique) is pressure that the ozone gas of 2700Pa (unstrpped gas 9 times) is incorporated into the container that stuffing pressure is the silicon unstrpped gas of 300Pa (Maiba monocrystalline processing type) and compares with the mass spectral variation afterwards (gas composition in the gas phase) and the situation of amount of oxygen identical (2700Pa) wherein before.Measuring condition is, is 10 with stagnation pressure ^-2The gas of Pa is as sample and be incorporated into quality analysis and estimate in the container.

[0058] be under the situation of TEOS in unstrpped gas, when introducing the ozone gas of 9 times of voltage ratio unstripped gas heights, ozone gas almost completely is decomposed, and mass unit m/e ⁺=18, m/e ⁺=28, m/e ⁺=32, m/e ⁺=44 (correspond respectively to H ₂O, CO or SiO, O ₂And CO ₂) become the key component of gas.On the other hand, under situation about oxygen being incorporated in the container, the phenomenon of these lower-molecular-weight components appears no longer being decomposed into.

[0059] under the situation of TMS, has with composition shown in Figure 5 and estimate identical tendency.But, be noted that the ozone gas of 9 times of amounts of introducing makes ozone gas excessive because under the situation of TMS, therefore can determine that extra ozone gas is arranged (interruption of the signal of mass number 48) in gas phase.

[0060] in this respect, under the situation of TEOS, find that decomposition is inadequate when introducing the ozone gas of 3 times and 6 times amounts.That is to say that under the situation of TEOS, when the amount of the ozone gas of introducing, with respect to the pressure of the TEOS under the TEOS of constant gas pressure unstrpped gas atmosphere and opinion, when increasing by 3 times, 6 times and 9 times, discovery characteristic pattern as shown in Figure 6 is such, H ₂O, CO (SiO), O ₂, CO ₂Formation increased.That is to say, can think the decomposition reaction of having carried out more effective and better organic substance.

[0061] system's (reactor) is under the situation of sealing after gas is introduced, and pressure raises, and this shows have extra ozone gas to exist in internal system, if ozone gas additionally is present in the words of internal system.If it is not enough that the quantity of ozone gas becomes, then will reduce the quality of film as described as follows.Thus, desirable is to set a kind of condition, like this, just the pressure of system can be raise after the introducing of ozone gas finishes and be fixed up all the time.

[0062] next, relate to the air inflow ratio between ozone gas and the unstrpped gas, the introducing pressure limit of the unstrpped gas of each circulation can be quantified as certain condition,, makes that unstrpped gas can produce sufficient decomposition under the gas phase of determining that is.That is to say, estimate when feedstock gas pressures is higher that film thickness (that is the film thickness of a circulation time deposition) becomes thicker after ozone supplied subsequently.But, because the gas pressure that is incorporated in the reactor is very high, therefore estimate, the controllability of the chemical reaction of unstrpped gas and ozone gas and the amount of impurities (for example, the water of inadequate oxide and formation around film in the carbon series) that is received when deposition takes place the reaction caudacoria change.

[0063] following result of experiment shows, when base material temperature is low, must reduce the unstrpped gas supply pressure, and must reduce the SiO that each circulation is deposited ₂The thickness of film.The stowing pressure of unstrpped gas will be different along with gases used kind.But, under the situation that the film thickness that a circulation (unstrpped gas supply+ozone gas supply) forms can be regulated, the SiO of deposition ₂The thickness range of film is: be 0.2nm (SiO when base material temperature is 200 ℃ ₂An atomic layer) to the scope of 1nm, be 0.2nm (SiO when base material temperature is 300 ℃ ₂An atomic layer) to the scope of 5nm.When the silicon dioxide film that deposits is in any one above-mentioned scope, can deposit the high-quality film that obtains having high film density and have series of low-carbon impurity introducing degree.Therefore, as the SiO that under higher speed, forms deposition ₂During film, that is, when feedstock gas pressures increased, chemical reaction mainly occurred in unstrpped gas and arrives in the substrate surface gas phase before, does not find the reaction of substrate surface.This is that the byproduct of reaction such as the water that form under high relatively concentration are brought in the substrate surface because exist with relative high concentration in the process of unstrpped gas on being deposited on substrate surface.

The details of experimental result will be described [0064].

[0065] the supply dividing potential drop of (experimental technique) ozone is fixed on 2700Pa.In following experiment, HMDS is as unstrpped gas.Feedstock gas pressures is changed to 300Pa, 150Pa, 50Pa and 10Pa.Be under 200 ℃ the situation at base material temperature, find that with after the feedstock gas pressures repeated deposition of 300Pa, it is opaque that oxidation film becomes.That is to say that finding has a large amount of organic substances and reactive intermediate product (inadequate decomposition molecule) to be introduced in the oxidation film.This means that unstrpped gas is decomposed on the position that occurs in away from machined surface by ozone gas.In addition, when oxidation film when unstrpped gas is equal to or less than the 150Pa deposit, can high accuracy be suitable for such model, that is, suppose the body SiO of the oxidation film of deposition ₂Optical characteristics (refractive index and extinction coefficient).

[0066] Fig. 7 shows the result who studies film forming speed (through the optical film thickness of spectrum ellipsometric measurement instrument) with base material temperature, raw material dividing potential drop and alternate supplies number of times as parameter.If can from the characteristic pattern of Fig. 7 understand like that, can determine that along with the raising of feedstock gas pressures with along with the raising of the alternately gas supply number of times ratio that repeats, optical film thickness increases.That is to say that the two all can become the parameter that can be used for pinpoint accuracy ground control film forming speed the alternately gas supply number of times of feedstock gas pressures and repetition.Also showing in addition, is under 200 ℃ the situation at base material temperature, and particularly in the high high speed film forming procedure of feedstock gas pressures, film forming speed is high under 300 ℃ the situation than base material temperature.

[0067] in addition, when unstrpped gas when the HMD that wherein comprises two Si atoms molecule becomes the TMS that wherein comprises a Si atom in molecule, film forming speed reduces to 10nm, and (approximating feedstock gas pressures greatly is 10Pa, base material temperature is 300 ℃, half of the 18nm during ten circulation-supplied).That is to say that can determine, the silicon atom number changes pro rata in film forming speed and the unstrpped gas.

[0068] next, in order to study the tightness of these oxidation films, studied the wet etching speed of oxidation film.In etch process, use 200: 1 buffered hydrofluoric acid.As shown in table 1, as can be known, when base material temperature become higher, when feedstock gas pressures becomes lower, it is lower that etch-rate becomes, that is, it is finer and close that oxidation film becomes.

Etch-rate when [0069] table 1 deposited film (during deposition) that shows alternate supplies was with 200: 1 buffered hydrofluoric acid etch.

[0070] [table 1]

Base material temperature (℃)	300	300	300	200	200
						Feedstock gas pressures (Pa)	10	50	150	10	50
Etch-rate (nm/min)	37	41	43	50	62

[0071] in addition, find that estimate according to the following Fourier transform infrared of describing is absorbed, when forming the film thickness thickening of film and each cycling deposition at a lower temperature, the hydrogen that stays in the film (being caused by water) increases.

[0072] Fig. 8 shows the characteristic pattern of expression typical FTIR spectrum (Fourier transform infrared absorption spectrum) (200 ℃, 50Pa, 10 times).In Fig. 8, the feature of (1) expression Si-OH, the feature of (2) expression carbon dioxide, the dotted line of sign (3) is represented background, the feature of the Si-O-Si key that (4) expression stretches, the feature of (5) expression Si-OH, (6) feature of the feature of expression Si-OH distortion and (7) expression Si-OH vibration.In addition, table 2 shows the signal strength signal intensity ratio between the Si-OH signal peak and Si-O-Si signal under peak position, half-peak breadth value and each membrance casting condition of the stretch mode of Si-O-Si key under each membrance casting condition.To each sample, film thickness all is aligned to 18nm in optical thickness.

[0073] when having many protoxide in the film, the variation of the bond angle of Si-O-Si key just brings the Si-O-Si peak position to increase towards the displacement and the half-peak breadth value of low frequency one side.

[0074] table 2 shows the peak position of Si-O-Si stretch mode, half-peak breadth value, and Si-OH (95nm)/Si-O-Si peak signal strength ratio.

[0075] [table 2]

	Embodiment						Comparative Examples
									1	2	3	4	5	6	Thermal oxide film
Film-forming temperature (℃)	300	300	300	200	200	200
								HMDS feed pressure (Pa)	10	50	150	5	10	50
Peak position (cm -1)	1063	1065	1065	1066	1067	1067	1080
								Half-peak breadth (cm -1)	75	70	66	75	71	85	75
The Si-OH/Si-O-Si signal strength signal intensity	0	0.05	0.136	0.05	0.205	0.461	0

Comparative Examples is by obtaining in the thermal oxide film formation method described in the above-mentioned background technology.

[0076] that is to say (film forming thickness of each circulation: 1nm), estimate to have prepared the desirable Si-O-Si key that in oxidation film, has less hydrogen content under 10Pa, 300 ℃ process conditions.Even under 200 ℃ process conditions,, and make that the film thickness of each cyclic deposition is lower if reduce the dividing potential drop of unstrpped gas, also can be implemented in CVD reaction, and can prepare high-quality oxidation film near the substrate surface place.

[0077] next, will prepare on this structure deposition and obtain MIS (metal-insulator semiconductor) structure of Al (aluminium) electrode, and estimate it as the dielectric film characteristic.

The characteristic pattern of the electric field strength that the leakage current density on [0078] Fig. 9 shows expression and is applied to film is relevant.Estimate the film that forms down at 300 ℃ by IV mensuration (with the relevant electric field strength of leakage current density on being applied to film).Find, in feedstock gas pressures is to prepare the high quality oxide film that film thickness is the 1nm/ circulation under the 10Pa, it is that film thickness under the 50Pa is that the oxidation film of 5nm/ circulation is compared with feedstock gas pressures, leakage current is smaller slightly in low electric field application process, and, even under above two kinds of conditions, oxidation film is also because breakdown field strength is 8MV/cm and have sufficient characteristic as cvd film.

[0079] (second embodiment)

Figure 10 is the schematic structure view of the oxidation film forming device in second preferred embodiment.

Oxidation film forming device in [0080] second preferred embodiment is equipped with light source 15 in reactor 10 inside, is used for ultraviolet light (laser) is shone base material 100.Therefore, ultraviolet light is installed and introduces window 16 on reactor 10.Ultraviolet light is introduced window 16 and can be made with known material, if this material can be by its transmission ultraviolet light.Unit heater 14 can freely be regulated the installation site of base material 100.

[0081] wavelength of the oxygen atom of the excitation state that forms on ozone owing to rayed when being equal to or less than 8.3eV (Si-O bond energy) when luminous energy of the wavelength of ultraviolet light (laser) is corresponding, described luminous energy is greater than the bond energy (4.8eV) of O-H key, and this O-H key is a main component of staying oxidation film inside.As the light source of ultraviolet light (laser) of this wavelength of irradiation, for example can use Cooper-Hewitt lamp (wavelength=185nm), Xe ₂Excited quasi-molecular lampbulb (wavelength=172nm), etc.

[0082] said structure of this embodiment can form the condition of the following stated, that is, the Hydrogen Energy of staying silicon dioxide film inside under this condition is at an easy rate by desorb.In addition, the higher ultraviolet light brightness (energy density) of preferred generation.Higher brightness makes because the absorption ultraviolet light forms higher excited oxygen atomic concentration, and makes that the diffusion length of oxygen atom is longer in the oxidation film.That is to say that this is because increased the degree of depth that transforms (for example, thereby Si-C key and Si-H key be cut off the spatial depth that makes it possible to the Si-O key of inside is substituted onto the outside of film).

[0083] irradiation of ultraviolet light (laser) not only can be in containing the supply process of ozone gas (ozone conversion process as shown in Figure 2), and at any time in the process.In detail, in the gas process that supplies raw material irradiating ultraviolet light (laser) make c h bond, Si-C key and Si-H key (each all has low bond energy) in the chemical bond of unstrpped gas of supply before the ozone gas supply by early cut-off, although unstripped gas is known from experience the absorbing light quantum.These bond energys are less than 4.8eV.But, shown in the Figure 4 and 5 of first embodiment, these almost completely decomposition owing to be exposed to containing ozone gas under of abundant amount.Therefore, the irradiation of ultraviolet light is not necessary.

[0084] makes described film in the irradiation of ozone gas supply process medium ultraviolet light (laser), even under higher deposition rate, compares also have equivalent characteristic with those films that under the same terms of realizing first embodiment, form.Can think, this be because with the ground state oxygen atom relatively, the excited oxygen atom that forms owing to UV-irradiation has high degree of oxidation, and has under the silicon unstrpped gas atmosphere of substrate surface due to the diffusion length of growing staying.

[0085] as the restriction of equipment size, desirablely be to make that introducing window 16 from ultraviolet light is smaller than the representational absorption degree of depth (intensity of incident uv is 1/e) of the ultraviolet light that uses when being equivalent to supply ozone partial pressure to base material 100 surfaces apart from d.This makes can more effectively generate the excited oxygen atom at substrate surface, and realizes the CVD reaction and form high-quality oxidation film near substrate surface.

[0086] the following operation embodiment that will describe the oxidation film forming device in second embodiment.

[0087] under the situation of using HMDS, ultraviolet pulse laser (KrF excimer laser, wavelength: 248nm, power density: 200mJ/cm ², repetition rate: it is to form film together with HMDS under the condition of 4cm to the substrate surface distance that irradiation 100Hz) causes introduce window from irradiation.Can obtain having the film of low hydrogeneous (water) percentage, and the insulation characterisitic of this film identical with described in first embodiment, it is under 200 ℃ film-forming temperature situation, and growth rate circulates up to 2nm/, under 300 ℃ film-forming temperature situation, growth rate circulates up to 10nm/.

[0088] aforesaid this high speed film forming, that is, the film thickness increase that each circulation forms makes shorten process time, disposal ability increases.

[0089] (the 3rd embodiment)

Figure 11 shows the technological process relevant with the oxidation film forming device of the 3rd preferred embodiment.In Figure 11, (P ₀) refer to the pressure that exhaust arrives (for example, 1Pa), (P ₁) refer to unstrpped gas stuffing pressure, (P ₂) guide the pressure behind the ozone.Notice that a circulation will be set to, for example, 1 second to 10 seconds.

[0090] the oxidation film forming device in the 3rd embodiment, as shown in figure 11, in the process of gas that supplies raw material, the temperature of base material 100 is set in room temperature, after this, and according to the opportunity of supply ozone gas, be set to predetermined temperature (for example, 300 ℃) with the pulsation form.

[0091], finds to follow the organic substance key around silicon, as CO as described in the experimental result of first embodiment ₂And H ₂O, even at room temperature also can be decomposed owing to the gas-phase reaction between unstrpped gas and 100% ozone, if ozone gas divides pressure energy that enough pressure is provided.That is to say, if water (hydrogen) is melted in the film in the oxidation film conversion process, it just can be eliminated effectively so, and described film only remains on the condition of high temperature in supply contains the process of ozone gas, like this, just can prolong the oxidability of ozone and the diffusion length of oxygen atom.Therefore, can prepare high-quality dielectric film.In this case, can to improve or reduce the heating means of the temperature of base material 100 in the extremely short time be desirable in employing.Thus, make reactor (system) temperature inside can be set in stationary temperature at an easy rate.In addition, the temperature in the spatial distribution of near surface unstrpped gas also becomes and is easy to be in steady state value.Therefore, the concentration of unstrpped gas (the atom number of plies) become too be easy to be in constant.Therefore, the film thickness of silicon dioxide film demonstrates further high uniformity.

[0092] apparent from foregoing, according to each the oxidation film forming device in above-mentioned first, second and the 3rd embodiment, contain ozone gas and unstrpped gas because can't supply simultaneously, promptly, the feeding manner that adopts be with contain ozone gas guide into exist in the reactor (for example have utmost point low-pressure (molecular density), in unstrpped gas 10Pa), so the high-concentrated ozone gas that has a high reactivity for organic substance (for example, 100% ozone) can be used as oxidant gas, and not need to consider its danger as oxidant.

[0093] in addition because unstrpped gas filled equably the space and, afterwards, filled be enough to complete oxidation unstrpped gas contain ozone gas in a large number, even when machining large-sized base material, also can obtain the technology of high uniformity.Under the situation of carrying out gas flow process, can't avoid the fluctuation space wave of molecular density of unstrpped gas and ozone gas (result from) of the steric course that brings by air-flow.But aforesaid this problem does not exist in each the oxidation film forming device in first, second and the 3rd embodiment.

[0094] in addition, first, in each oxidation film forming device in the second and the 3rd embodiment, alternate supplies unstrpped gas and contain the method for ozone gas and the ALD method (ALD is a kind of like this method, wherein pass through gas supply subsequently, to being adsorbed on lip-deep molecular raw material gas and transforming to stop mode automatically, deposit the film of an atomic layer, and this step cycle ground repeats) compare, the film that each circulation is deposited is thicker, described ALD method is an important techniques of film in recent years, is the method for highly control and the method for large tracts of land deposition.Therefore, the film of each cyclic deposition can thickening.Like this, can reduce the number of times that is used to obtain the required repetition feed of constant oxidation film film thickness.So just can reduce film formation time and increase disposal ability.Particularly, according to the oxidation film forming device of second embodiment, can realize each film forming speed faster that circulates further.

[0095] in addition, with up to the present through being commonly used for the H of ALD technology oxidant ₂O etc. compare, owing to use ozone and because the high reaction activity of ozone, can shorten the process time of each circulation.That is to say that because the ozone that uses is dry gas, therefore, the vapour pressure such as the water that stay in the reaction post-reactor are very low, do not have the gas that is difficult to by the dry pump discharge, therefore, exhaust accelerates.

[0096] in addition, because the amount of the utilization ratio that ozone gas improves and its use is few, therefore, can reduce load for gas extraction system.Although the main high frequency power feed system of using is discharged in the manufacture process of ozone gas,, with regard to carrying capacity of environment, (in making ozone, need electric power), using ozone gas with minimum requirements is that everybody is desirable.Each oxidation film forming device in first, second and the 3rd embodiment all satisfies above-mentioned viewpoint.

[0097] in addition, according to the oxidation film forming device of the 3rd embodiment,, therefore, realize uniform CONCENTRATION DISTRIBUTION (unstrpped gas and contain ozone gas) easily because all temperature of internal system is all constant in room temperature.Like this, just might realize even processing.In addition, carry out to heating pulse.Therefore, compare, can instantaneously reach a high temperature with continuous heated substrate.Therefore, the diffusion length of ozone can not only obtain extending (that is to say, can increase each formed film thickness that circulates), and, can eliminate hydrogen and the water system impurity stayed easily in the silicon dioxide film effectively.

[0098] forms the method and apparatus of oxidation film according in first, second and the 3rd embodiment each, can prepare even and high-quality dielectric film, can also bring into play the capacity of decomposition of high-concentrated ozone gas effectively simultaneously organic substance.Therefore, even in being equal to or less than 300 ℃ low temperature process also can prepare high-quality dielectric film.

[0099] in addition, at base material with the polysilicon series raw material (for example is, polysilicon or amorphous silicon) under the situation about making, preferably before alternately supplying CVD unstrpped gas and containing ozone gas, (for example, the ozone gas that contains 100sccm) deposits one (for example, 1 minute constant period of cvd film with the constant flow rate supply in advance, surface temperature is the CVD film-forming temperature), thus in advance on substrate surface the preparation scope be the thermal oxide film of 0.2nm to 3nm.

[0100] below reason will be described.The step coverage rate of known cvd film and adhere to a great extent will be according to the surface state of deposition (for example, difference between hydrophily and the hydrophobicity, surface profile, roughness or the like) change (list of references: people such as Yoshie, TechnicalReport (Shingakugiho) of the Institute of Electronics, Information and Communication Engineers of Japan, SDM 94-150,71 pages (1994-11)).

[0101] for example, when the polysilicon base material was in the atmospheric environment, the natural oxide-film (film quality low) of thickness in the 0.2nm-0.6nm scope was the part growth.This substrate surface has the polysilicon plane and the silicon dioxide film of various crystal-plane-index.Therefore, do not wish it as the CVD deposition surface.For the deposition that realizes that uniformity is better, repeatability is high, the state of control substrate surface becomes extremely important.

[0102] therefore, verified is, when this substrate surface during by ozone oxidation, high-quality (height-density) silicon dioxide film that uniformity is better, film thickness density is higher obtains growth.That is to say that the thermal oxidation of ozone makes the substrate surface state obtain more uniform control.

[0103],, can prepare and have an atomic layer (for example, silicon dioxide film 0.2nm) as the thickness of thermal oxide film from the angle of control surface state.Angle from dielectric film, it is desirable to, the thickness that wherein straight tunnel current does not flow is that the thermal oxide film of 3nm is grown on the film of ozone thermal oxidation in advance, thereby plays the effect (just having improved adhering between cvd film and the base material like this) of interface resilient coating.Consider these contents, the preferred for preparation scope is the thermal oxide film of 0.2nm to 3nm.But, be noted that because of thermal oxide film for the 3nm that grows, process time is elongated, the disposal ability step-down, therefore, in fact, may preferred described film be processed effective process time (about ten minutes) under the ozone gas condition of 300 ℃, 1 atmospheric pressure and 10 volume % at base material temperature.Therefore, can form thermal oxide film in about 1nm to the 2nm scope of thickness.

[0104] in addition, when forming thermal oxide film, UV-irradiation even then under low temperature (for example, room temperature), also can form at short notice and has enough film thicknesses (for example, higher-quality thermal oxide film 3nm) on base material.In this case, because can form preferred thermal oxide film under low temperature such as room temperature, therefore, it is no longer necessary that the heating of base material may become.As the ultraviolet light that is used to shine, can use Cooper-Hewitt lamp (wavelength=185nm) or Xe ₂(wavelength=172nm), both luminous energy is equal to or is lower than 8.3eV excited quasi-molecular lampbulb, and the gross energy layer is greater than 4.8eV.

[0105] (the 4th embodiment)

In addition, not only in the preparation silicon dioxide film, and in the preparation metal oxide film, contain organometallic unstrpped gas and contain ozone gas and can alternately be supplied to base material.At this moment, the oxidation film forming device in this embodiment can adopt and first, second and the identical structure of each oxidation film forming device described in the 3rd embodiment.

[0106] application of metal oxide film is very wide, as the gate insulation film of LSI (capacitor) purposes, and ferroelectric film, the gate insulation film of TFT (thin-film transistor) purposes, and nesa coating.The thickness of these films greatly about about 1nm to about 100nm scope.Sputter or the like) and pulsed laser deposition according to its film thickness and film quality, suitably used ALD (ald), CVD (chemical vapour deposition:.For described film, in order to provide metal oxide film (comprising silicon dioxide film) (to have the film of the lattice constant mismatch of little degree with base material, for example, forming at the interface, be used between film and base material, producing higher adhering to), the multiple composition that further need have any film thickness at depth direction, for example, Ta ₂O ₅(tantalum pentoxide) and SiO ₂The laminated film of (silicon dioxide) or its Sr (strontium) _xBa (barium) _yO (oxygen) _zComposition x, y and z at the vicissitudinous film of depth direction.

[0107] ALD (ald) is a kind of method that forms film by the base material feed in reactor circularly.Circulation-supplied unstrpped gas and oxidizing gas cause functional group on the substrate surface by chemical reaction and replaced, and by controlling the formation that each atomic layer advances film.Be easy to obtain having the film of high film density and stoichiometric composition.But, be noted that because of the absorption of the speed of growing to be controlled owing to unstrpped gas, therefore, the problem that exists disposal ability (film forming speed) to reduce.

[0108] on the other hand, especially MOCVD (metallorganic CVD) method that is widely used as most the CVD method is a kind of like this method, wherein supply organic metal gas and oxidizing gas, make it flow on substrate surface with gaseous form, the metal remained oxidate gets off owing to the chemical reaction of two kinds of gases.Can realize that conformal film forms, the disposal ability of this technology is big, and projection and depression are seldom.But such as impurity, therefore the problem of staying easily on the metal oxide film as carbon, hydrogen etc. has but increased.

[0109] although replaces normally used water or oxygen molecule as oxidant by using such as the contour active gases of ozone, the reduction process ability of ALD is improved by shortening the required reaction time (replacing surperficial end group), but all will deposit for each atomic layer.Therefore, be difficult to be significantly improved.In order to remove impurity, can consider to use the method for ozone in the MOCVD method with high organic substance capacity of decomposition.But, when in the MOCVD method, using ozone with high concentration gas (being equal to or higher than several ppm), but be difficult to carry out the even processing of film quality and film thickness.Can think, because the high de-agglomeration ability of high-concentrated ozone gas, because the ozone concentration difference between gas upstream side and the downstream has produced the spatial coherence during CVD reacts.Yet, when using concentration of ozone gas to be equal to or less than the low concentration ozone gas of hundreds of ppm, can realize uniform processing technology.

[0110] in the 4th embodiment under low-pressure state alternate supplies ozone with high concentration gas solved the reduction process capability problems of ALD method, remove the low problem of ability of carbon elimination series impurity in low consistency problem between airflow MOCVD and the high-concentrated ozone gas and the MOCVD method.

[0111] known, the diffusion length of oxygen atom is different along with the difference of metal species in metal by the preparation of sputter or pulsed laser deposition or the metal oxide film, but in 10nm arrives the 20nm scope (for example, referring to Japanese Laid-Open Patent Application (tokkai) No.2004-137101).It is a very delicate thing that the growth that is equal to or less than an atomic layer by ALD utilizes the oxidability (diffusivity) of ozone fully.That is to say that if sufficiently high words of ozone concentration on the substrate surface after the organic substance gas reaction, even deposited maximum, promptly the metal oxide film of the about 10nm of each pulse also can form the oxidation film with insufficient oxide layer.The film forming speed of each pulse described in first embodiment is, under optimum condition, have covalent bond with and the oxygen atom SiO that is difficult to spread ₂Situation under and be that each pulse 0.2nm is to each pulse 5nm under 300 ℃ the situation at film-forming temperature.When the oxygen atom in metal oxide film can spread widelyr and require under higher speed the preparation thick film, for above-mentioned condition without any qualification.It is also noted that when gas pressure became higher, the CVD in this technology reacted on the position that occurs in away from substrate surface.Even can't form therein in the technology of non-homogeneous air-flow, film thickness and film quality also can change along with the distance between ozone gas inlet and the film.Therefore, consider the even processing of large scale base material, in fact may preferred above-mentioned condition.

[0112] in addition, compare with the MOCVD method, because atmosphere is the low-pressure state that does not use carrier gas and non-homogeneous air-flow does not take place, therefore, even thermal decomposition takes place hardly also under high-concentrated ozone gas, the life-span is long, and macroscopic air-flow phenomenon does not take place.Therefore, the distribution of film thickness and film quality appears not too easily.In addition, even thereby the preparation oxidation film makes under the situation that occurs the variation of oxidation film composition on the depth direction in layer structure, with in addition obtain at corresponding film thickness under the situation of strict control, unstrpped gas and contain ozone gas the two the pressure adjusting and the conversion that is used for each unstrpped gas mutually can deal with these situations.In addition, because be emptied completely, therefore, there be an advantage between pulse, not exist exactly and interfere with each other according to the gas that forms after each pulse of reaction.On the other hand, under the situation of MOCVD method, for the uniformity (not forming the situation of exhaust) that keeps technology, general measure is, the raw gas concentration of reactor downstream side is set in 99.9 volume % or higher.But this can reduce the utilization ratio of gas, and increases the load of gas extraction system.

[0113], can enumerate to comprise and wherein have metallic element-the organometallic gas of oxygen key or metallic element-carbon bond as preparation metal oxide film required unstrpped gas.For example, can adopt the organic metal unstrpped gas that is used for ALD method, MOCVD method etc.More particularly, be by TiO at oxidation film ₂Under the situation that (titanium dioxide) is made, can be TTIP (tetraisopropoxy titanium), TPT (tetra isopropyl titanate) etc.Forming by Al ₂O ₃Under the situation of the oxidation film that (aluminium oxide) made, can be Al (CH ₃) ₃(trimethyl aluminium) etc.In addition, when forming by HfO ₂During oxidation film that (hafnium oxide) made, can enumerate Hf (OC ₄H ₉) etc.

[0114] then, with with the same method of each embodiment as mentioned above, the ozone gas of alternate supplies organic metal unstrpped gas and high concentration (100%), make key between metallic element and the C (carbon), side chain C-H, and other organic keys can complete rupture, and make and to reduce the organic substance of staying in the film this is using traditional oxygen and water to show it is imperfect in as the ALD of oxidant and MOCVD method.It is also noted that, from the situation of the key of HMDS, because the bond energy of c h bond is 4.3eV, therefore, if the atom that combines with metallic atom (for example, C, H, N, or O) binding energy be equal to or less than this value, the then bond fission that can realize ideal and desirable oxidation.

[0115] in addition, in the process of preparation metal oxide film under the steam situation about forcing down, the well-known vaporizer that is used for introducing CVO unstrpped gas can the mode identical with the MOCVD method with traditional ALD use.All metals that feasible organic metal unstrpped gas with stable vapour pressure exists all can be used to prepare metal oxide.In this case, feed can be as SiO to the ozone gas pressure or the ozone partial pressure of corresponding metal in the process of introducing ozone gas ideally ₂Such under the situation, by being equivalent to make unstrpped gas introduce (metal oxide+CO with the pressure of the required amount of chemical equivalent form complete oxidation ₂+ H ₂O+ (NO ₂: under the situation comprising the N atom)).

[0116], can enumerate Al as the metal oxide film that forms in this embodiment ₂O ₃(pellumina), Zr ₂O ₅(zirconium oxide film), HfO ₂(hafnium oxide film), Ta ₂O ₃(tantalum-oxide film), TiO ₂(titanium dioxide film), ZnO (Zinc oxide film), or the like.

[0117] in addition, in this embodiment, when base material with the polysilicon series raw material (for example is, polysilicon or amorphous silicon) with the 3rd embodiment in same mode when making, in advance (for example contain ozone gas with constant flow rate, 100sccm) be supplied in the reactor one constant period of base material (for example, 1 minute, base material temperature is the CVD film-forming temperature), so that on substrate surface, be pre-formed the thermal oxide film of 0.2nm to 3nm, carry out the deposition of metal oxide film subsequently, afterwards alternate supplies unstrpped gas and contain ozone gas.

[0118] according to the method for the formation oxidation film of this embodiment, with first, second and the 3rd embodiment in same mode, can make the formation of film have the utilization ratio of raising and high disposal ability.In addition, compare with ALD, gas unnecessary in the gas phase is discharged by air purge rather than gas purging.Shortened the reaction time.In addition, compare, occur air-flow heterogeneous not too easily with MOCVD.Therefore, in the method for the use ozone gas of routine, because the difference of high temperature substrate surface gas upstream side and gas downstream ozone concentration, be difficult to guarantee the uniformity of film quality and film thickness.But, the method for the described formation oxidation film of each embodiment according to the present invention, because alternate supplies unstrpped gas and contain ozone gas, so it carries out under low-pressure state.Therefore, though the concentration of ozone gas height, thermal decomposition appears hardly, and the life-span is permanent, occurs macroscopic air-flow not too easily, and the distribution of film thickness and film quality also takes place simultaneously not too easily.Therefore, realized the preparation of even and high-quality oxidation film.

Claims (21)

1. method that forms oxidation film, described method comprises:

Alternately comprise the organosilicon of (silicon)-O (oxygen) key that has Si or Si (silicon)-C (carbon) key or have the organometallic unstrpped gas of metallic element-oxygen key or metallic element-carbon bond and contain ozone gas, on the surface of base material, to form oxidation film to the base material supply;

Regulate base material temperature in the scope of room temperature to 400 ℃; With

Adjusting contains the ozone concentration of ozone gas in the scope of 0.1 volume % to 100 volume %.

2. the method for the formation oxidation film of claim 1, wherein alternately supplying raw material gas and containing in the circulation of ozone gas, comprise in unstrpped gas under the situation of a silicon atom, the introducing pressure of unstrpped gas is in the scope of 0.1Pa to 100Pa, and comprise in unstrpped gas under the situation of n silicon atom, the 1/n scope of the introducing pressure of unstrpped gas is that unstrpped gas is introduced the upper limit of pressure value.

3. the method for claim 1 or 2 formation oxidation film is wherein supplied in unstrpped gas and is contained ozone gas being included in stoichiometric supply that organosilicon in the unstrpped gas or organic metal all be oxidized to silicon dioxide or metal oxide at least being equivalent to.

4. the method for the formation oxidation film of claim 3, the supply that wherein contains ozone gas is set at the amount that reaches following degree: supplied contain ozone gas after, be confirmable owing to being present in base material, unstrpped gas and containing that pressure that the thermal decomposition of the ozone in the capping system of ozone gas causes raises.

5. the method for each formation oxidation film among the aforementioned claim 1-4, wherein in each alternate supplies unstrpped gas and containing in the circulation of ozone gas, when the temperature of base material reduced, the film forming speed of each circulation reduced.

6. the method for the formation oxidation film of claim 5, wherein when base material temperature was 200 ℃, film forming speed was in 0.2nm/ is circulated to the scope of 1.0nm/ circulation.

7. the method for the formation oxidation film of claim 5, wherein when base material temperature was 300 ℃, film forming speed was in 0.2nm/ is circulated to the scope of 5.0nm/ circulation.

8. the method for each formation oxidation film among the aforementioned claim 1-7, wherein when alternately to supply raw material gas and when containing ozone gas of base material, with UV-irradiation on base material.

9. the method for the formation oxidation film of claim 8, reactor wherein is provided, in this reactor, when UV-irradiation is on base material, gas and contain ozone gas alternately supplies raw material, on substrate surface, forming oxidation film, and regulate the UV-irradiation window that is installed on the reactor and the distance between the base material, the absorption degree of depth that its ultraviolet light that is shorter than introducing is absorbed by ozone partial pressure.

10. the method for each formation oxidation film among the aforementioned claim 1-9, wherein reactor is low pressure cold-wall type or hot wall type.

11. the method for each formation oxidation film among the aforementioned claim 1-10, be under the situation about making wherein with the polysilicon series raw material at base material, to contain ozone gas and under constant base material temperature, be supplied to the constant time of base material with constant flow rate, on base material, to form thermal oxide film, afterwards again to alternately supply raw material gas and contain ozone gas of base material.

12. the method for the formation oxidation film of claim 11, wherein when forming thermal oxide film, UV-irradiation is on base material.

13. oxidation film forming device, wherein comprise and have Si (silicon)-organosilicon of O (oxygen) key or Si (silicon)-C (carbon) key or have the organometallic unstrpped gas of metallic element-oxygen key or metallic element-carbon bond and contain ozone gas and alternately be supplied to base material, on the surface of base material, to form oxidation film, described equipment comprises: a reactor, design this reactor with the unit heater that is used to hold base material of packing into; One is equipped with the pipeline that is used for unstrpped gas is introduced the unstrpped gas introducing valve of reactor; Another is equipped with and is used for introducing the pipeline that ozone gas is introduced valve that contains of reactor with containing ozone gas; And another is equipped with the pipeline that is used for the vent valve of the discharge of the gas in the reactor, when unstrpped gas introduce valve, contain that ozone gas is introduced valve and vent valve is opened-shutoff operation is with unstrpped gas with when containing ozone gas and alternately being supplied in the reactor, contain ozone gas and introduce the ozone concentration that valve will contain ozone gas and be adjusted to 0.1 volume % in 100 volume % scopes, and unit heater is adjusted to base material temperature in room temperature to the 400 ℃ scope.

14. the oxidation film forming device of claim 13, wherein unstrpped gas introducing valve and vent valve are opened-shutoff operation, alternately supplying raw material gas and containing in the circulation of ozone gas so that make, comprise in unstrpped gas under the situation of a silicon atom, the introducing pressure of unstrpped gas is in the scope of 0.1Pa to 100Pa, and comprise in unstrpped gas under the situation of n silicon atom, the 1/n scope of the introducing pressure of unstrpped gas is that unstrpped gas is introduced the upper limit of pressure value.

15. the oxidation film forming device of claim 13 or 14, the introducing valve that wherein contains ozone gas opens-and shutoff operation contains ozone gas with supply, and its supply is equivalent to and will be included in the chemical equivalent that organosilicon in the unstrpped gas or organic metal all are oxidized to silicon dioxide or metal oxide at least.

16. the oxidation film forming device of claim 15, wherein containing ozone gas introducing valve opens-shutoff operation, be set at the amount that reaches following degree so that will contain the supply of ozone gas: supplied contain ozone gas after, be confirmable owing to being present in base material, unstrpped gas and containing that pressure that the thermal decomposition of the ozone in the capping system of ozone gas causes raises.

17. each oxidation film forming device among the aforementioned claim 13-16, wherein unstrpped gas is introduced valve, is contained that ozone gas is introduced valve and vent valve is opened-shutoff operation, so that alternately supply raw material gas and contain ozone gas each the circulation in, when base material temperature reduced, the film forming speed of each circulation reduced.

18. the oxidation film forming device of claim 17, wherein when base material temperature was 200 ℃, film forming speed was in 0.2nm/ is circulated to the scope of 1.0nm/ circulation.

19. the oxidation film forming device of claim 17, wherein when base material temperature was 300 ℃, film forming speed was in 0.2nm/ is circulated to the scope of 5.0nm/ circulation.

20. each oxidation film forming device among the aforementioned claim 13-19 wherein is equipped with on the reactor and is used for the light source of UV-irradiation on base material and is used for UV-irradiation window by the ultraviolet light of its transmission irradiation.

21. the oxidation film forming device of claim 20, wherein unit heater is regulated the position of base material, the absorption degree of depth that the ultraviolet light that makes distance from the UV-irradiation window to base material be shorter than introducing is absorbed by ozone partial pressure.

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