GB2061243A - Method of making semiconductor devices - Google Patents
Method of making semiconductor devices Download PDFInfo
- Publication number
- GB2061243A GB2061243A GB8029199A GB8029199A GB2061243A GB 2061243 A GB2061243 A GB 2061243A GB 8029199 A GB8029199 A GB 8029199A GB 8029199 A GB8029199 A GB 8029199A GB 2061243 A GB2061243 A GB 2061243A
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- United Kingdom
- Prior art keywords
- gas mixture
- silane
- silicon dioxide
- silicon
- temperature
- Prior art date
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 75
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 37
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 28
- WFPZPJSADLPSON-UHFFFAOYSA-N dinitrogen tetraoxide Chemical compound [O-][N+](=O)[N+]([O-])=O WFPZPJSADLPSON-UHFFFAOYSA-N 0.000 claims abstract description 27
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910000077 silane Inorganic materials 0.000 claims abstract description 23
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 239000000758 substrate Substances 0.000 claims abstract description 22
- 239000000203 mixture Substances 0.000 claims abstract description 19
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 17
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 claims abstract description 7
- 238000010438 heat treatment Methods 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 39
- 239000007789 gas Substances 0.000 claims description 24
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 3
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 3
- BUMGIEFFCMBQDG-UHFFFAOYSA-N dichlorosilicon Chemical compound Cl[Si]Cl BUMGIEFFCMBQDG-UHFFFAOYSA-N 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000003085 diluting agent Substances 0.000 claims 1
- 239000002019 doping agent Substances 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 13
- 229910052710 silicon Inorganic materials 0.000 abstract description 13
- 239000010703 silicon Substances 0.000 abstract description 13
- 238000011982 device technology Methods 0.000 abstract 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 15
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 10
- 238000000151 deposition Methods 0.000 description 9
- 238000005086 pumping Methods 0.000 description 8
- 230000008021 deposition Effects 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 239000001301 oxygen Substances 0.000 description 6
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 6
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 4
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 239000001272 nitrous oxide Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
- 230000005593 dissociations Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000010574 gas phase reaction Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 235000011007 phosphoric acid Nutrition 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
- C23C16/4408—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber by purging residual gases from the reaction chamber or gas lines
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/40—Oxides
- C23C16/401—Oxides containing silicon
- C23C16/402—Silicon dioxide
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
- H01L21/02126—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
- H01L21/02131—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC the material being halogen doped silicon oxides, e.g. FSG
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02205—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition
- H01L21/02208—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si
- H01L21/02211—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition the precursor containing a compound comprising Si the compound being a silane, e.g. disilane, methylsilane or chlorosilane
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
- H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
- H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
- H01L21/02164—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material being a silicon oxide, e.g. SiO2
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02107—Forming insulating materials on a substrate
- H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
- H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
- H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
- H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Formation Of Insulating Films (AREA)
Abstract
Silicon dioxide layers are deposited on semiconductor, eg silicon, substrates by heating a gas mixture comprising silane and/or dichlorosilane together with nitric oxide and/or dinitrogen tetroxide at a pressure below 20 Torr and at a temperature below 750 DEG C in a reaction vessel containing the semiconductor substrate. There is a need in semiconductor device technology to reproducibly form silicon dioxide layers of substantially uniform thickness, preferably at temperatures of not more than 750 DEG C, so as to avoid impairing the flatness of silicon substrates on which such silicon dioxide layers are formed.
Description
SPECIFICATION
Method of making semiconductor devices
The invention relates to a method of making a semiconductor device, the method including the step of depositing a silicon dioxide layer on a semiconductor substrate by low-pressure chemical vapour deposition (LPCVD), and to a semiconductor device made by such a method. The silicon dioxide layer formed may be either undoped or doped, usually with phosphorus, and is used for example in active M.O.S. gate structures, in diffusion masking, or for passivation purposes, when, for example, the silicon dioxide layer may be deposited over aluminium interconnecting patterns, which make it necessary for the silicon dioxide to be deposited at a low temperature, for example below 500"C.
A LPCVD process has been used in the manufacture of semiconductor devices to deposit silicon dioxide layers on semiconductor substrates, for example 100 mm diameter silicon slices, in which process silane (SiH4) is reacted with oxygen. Problems which are encountered with this process include the non-uniformity of the thickness of the deposited layer over the cross-section of a substrate, - the so-called "bullseye effect", the non-uniformity of the thickness of the deposited layer between different substrates in a batch, and variations in the thickness of the deposited layer on substrates in different batches. The reaction between silane and oxygen is a homogeneous reaction, that is to say silica is formed both in the gas phase and at solid surfaces within a reaction chamber.Consequently silica particles formed in the gas phase by this reaction may be trapped in the silica layers growing on substrates. These trapped particles produce local irregularities in the thickness of a silica layer formed on a substrate and give rise both to the formation of porous layers, and as a consequence of such particles becoming detached from a deposited layer, the presence of pinholes in the finished layers.
Furthermore, the definition of silica layers produced by this method over steps and in re-entrants formed during a previous etching step may not be satisfactory.
United Kingdom Patent Specification 1,520,051 describes a method of manufacturing a semiconductor device, which method includes the step of forming a polycrystalline silicon layer doped with from 2 to 45 atomic percent of oxygen atoms by a chemical vapour deposition process in which silane is reacted with nitrous oxide. The specification contains no disclosure ofthe pressure at which this process is conducted. The specification states that a silicon dioxide layer is formed over the oxygendoped polycrystalline silicon layer and is produced by reacting silane with oxygen. The nitrous oxide used to form the oxygen-doped polycrystalline silicon may be replaced by nitric oxide or nitrogen dioxide.
The object of the invention is to provide low pressure chemical vapour deposition processes for depositing silicon dioxide layers by essentially heterogeneous reactions, which are more reproducible than the known LPCVD silicon dioxide processes, and in particular to provide such a LPCVD process which can be conducted at temperatures below 750 C, or even for some applications at temperatures below 500 C. There is now a desire in integrated circuit technology to avoid any processing of silicon bodies after growth of monocrystalline silicon, which involves heating the silicon bodies above 750 C, since such heating may cause mechanical deformation of the surfaces of the silicon bodies.
The invention provides a method of making a semiconductor device, the method including the step of producing a silicon dioxide layer on a semiconductor substrate by heating a gas mixture comprising silane andlor dichlorosilane (SiH2Cl2) together with nitric oxide and/or dinitrogen tetroxide at a pressure below 20 Torr and at a temperature below 750 C in a reaction vessel containing the semiconductor substrate.
During the investigations which led to the present invention, it was noted that the LPCVD process used to deposit polycrystalline silicon from a gas mixture consisting of silane and nitrogen at a pressure of from 0.2 to 15 Torr gave a fine-grained deposit having a substantially uniform grain size. This process is reproducible and is not critical with respect to temperature - the deposition rate increases by approximately 2% per degree Celsius rise in temperature at 650 C. It appears that this polycrystalline silicon LPCVD process is a heterogeneous process, that is the reaction only occurs at a surface, the rate of reaction being limited by the rate of adsorption of silane on a surface, there being a steady rate of desorption of hydrogen from the surface.It is surmised that the uniformity of the deposit formed is due to the reaction being heterogeneous and surface-dependent.
The silane/oxygen LPCVD was extensively examined during the investigations which led to the present invention, and it was found that both the temperature and pressure at which the process is conducted are critical. When the operating pressure was increased significantly above 2 Torr, long whiskers grew on the edges of the semiconductor substrates and across the front surface of the first substrate traversed by the gas mixture. There was clear evidence of homogeneous gas phase reaction, and this is a major difference from the polycrystalline silicon LPCVD process, where deposition only occurs by a heterogeneous gas phase reaction on the semiconductor substrates and on the hot wall of the diffusion furnace in which the process is conducted.It was noted in the SiH4/02 LPCVD process that there was a heavy deposit of silicon dioxide on the furnace wall in advance of the reaction zone in which the semiconductor substrates were located, the thickness of the deposit increasing with increasing temperature of the furnace wall.
It was noted that in the SiH4/N2O process, the optimum operating temperature is the temperature at which the simple thermal decomposition of N2O becomes significant. The problem of the SiH4, O2 system is that it is too reactive, there is a significant rate of reaction at 20 C. It appears that what is required is a system which has a controlled equilib rium availability of oxygen, including, for passivation over aluminium interconnects, a system which can operate reproducibly in the temperature range from 400 to 500so.
A study was made of the feasibility of new LPCVD processes using silane andior dichlorosilane, together with nitrogen oxides. Excluding nitrous oxide, the other nitrogen oxides are related through the decomposition equilibria set out below.
Pure dinitrogen tetroxide boils at 22-C, and dissociates reversibly above this temperature. Dissociation into nitrogen dioxide is complete at 140'C.
Nitrogen dioxide reversibly dissociates on heating, dissociation being complete at 620so, when the vapour consists of an equilibrium mixture of nitric oxide and oxygen.
Nitric oxide decomposes irreversibly above 620"C.
2NO# < N2 + 02.
Between 620 and 700-C, this is a purely heterogeneous reaction. This reaction is of a mixed character between 700 and 1100 C, while in the range 1100 to 1300#C it is a substantially homogeneous reaction.
The form of the silicon input to the reaction may be modified by introducing hydrogen chloride gas into the mixture. The quantities of hydrogen chloride used, may be, for example, those having chlorine contents up to that equivalent to the chlorine content of SiH2Cl2 calculated with respect to the silane used.
However, smaller amounts of HCI may generally be used, which amounts would influence the kinetics of the process to a lesser degree than a quantity having a chlorine content equivalent to the chlorine content of SiH2Cl2, but which amounts have a significant influence on the dielectric properties of the deposited silica.
In one aspect of the invention, the gas mixture is formed by mixing silane and/or dichlorosilane with dinitrogen tetroxide, said gas mixture being heated at a temperature in the range from 400 to 550 C.
In another aspect of the invention, the gas mixture comprises nitric oxide together with silane and/or dichlorosilane, said gas mixture being heated at a temperature between 600 and 750 C.
Using silane/dinitrogen tetroxide mixtures in the temperature range 430-470 C, operating at a pressure of 1 Torr, oxide layers have been deposited with only small thickness variations across the area of the layer, these variations being confined to a small peripheral annulusofthe layer.
Similarly at 1 Torr and 650 C the silane/nitric oxide reaction has yielded very good quality oxides of even better uniformity.
Two embodiments of the invention will now be described with reference to the following Examples, and to the accompanying drawings, in which :- Figure 1 is a schematic side view of a longitudinal section of a low pressure chemical vapour deposition (LPCVD) apparatus suitable for performing a method according to the invention.
Figure 2 is a schematic side-sectional elevation of a MOS diffusion structure comprising silica flowglass and glassover layers which can be deposited by a method according to the invention, and
Figure 3 is a schematic side-sectional elevation of an apparatus used to detect pinholes present in silica layers which had been deposited by a method according to the invention.
Referring to Figure 1, a LPCVD apparatus comprises a 112 mm internal diameter silica furnace tube 1 which is 2 metres long, this tube 1 being provided with water-cooled end-seals 2, 3, one at each end of the tube 1. A flexible bellows 4 connects the end-seal 2 to a conduit 5 which leads to a pump system consisting of a Roots Turbine blower 6 type ER200 connected to an Edwards ISC900 rotary backing pump 7. At a pressure of 0.2 Torr, this pumping system is capable of an effective pumping speed for air of 10,000 litres/minute. The bellows 4 damp the vibrations transmitted through the conduit 5 from the pumping system. The furnace tube 1 is heated by means of a tubular electric furnace 8 provided with facilities (not shown) for controlling the temperature gradient along the length of the furnace.Silicon slices 9 which are to be coated with silica layers by a method according to the invention are !oaded into a jig 10. The loaded jib 10 is inserted into the tube 1 through the end-seal 3 and a door 11 on the end-seal 3 is then closed. The apparatus is provided with gas sources 12,13,15 and 16 of silane (or dichlorosilane), dinitrogen tetroxide (or nitric oxide), nitrogen and argon respectively. Pressure in the tube 1 is controlled by controlling the flowrate of nitrogen and/or argon from the sources 15 and 16 with the aid of a valve 17 operated by a Balzar control gauge (not shown) located in a gas supply line 18 connected to the throat of the Roots blower 6.
Figure 2 schematically shows a typical MOS diffusion structure 19 formed on a p-type silicon substrate 20 which includes phosphorus-doped source and drain regions 21 and 22 respectively. A field oxide layer 23 formed by wet thermal oxidation of the substrate at 9000C is provided with an aperture which extends over the major areas of the regions 21 and 22 and the area between the regions 21 and 22.
A gate oxide layer 24 produced by dry thermal oxidation at 10500C bridges the regions 21 and 22. A metallic gate 25 is located over the gate oxide layer 24. A 0.6 pim thick flowglass layer 26 is deposited by a method according to the invention at 450 C on the structure, and aluminium source, gate and drain interconnects 27, 28 and 29 respectively are deposited on the relevant areas. A 0.5 um thick glassover silica layer 30 is then deposited by a method according to the invention at 4500C so as to seal the structure, notably to prevent formation of orthophosphoric acid by hydrolysis of phosphorus pentoxide originating in the phosphorus contained in the source and drain regions 21 and 22. Any orthophosphoric acid produced in the structure would tend to corrode the aluminium interconnects.
During the investigations which led to the present invention, the rate of deposition from three gaseous silane-comprising systems, namely SiH4/N2O4, SiH4/
NO and SiH4/N2 were studied. The systems were studied at a pressure of 1 Torr with a total flowrate of 250 mis per minute. In the SiH4/N204 system, the gas stream consisted of 50 mis per minute of SiH4, 50 mis per minute of N204 and 150 mis per minute of argon. The SiH4/NO and SiH4/N2 systems each used gas streams containing 50 mis per minute of SiH4, together with 200 mis per minute of NO and N2 respectively. The activation energies of the SiH4/
N204, SiH4/NO and SiH4/N2 systems were 0.91 eV, 1.56 eV and 1.84 eV respectively.
The silane-nitrogen dioxide reaction may be described by the following equation : Iog(5m/6p) = - A E/kT + log A (1)
This equation (1) may be rewritten in the form om/6p = Ae (2) where m is the rate of deposition of silicon dioxide expressed in micrograms per sq.cm. per minute, p is the pressure in Torr, A is a constant, A E is the activation energy for the process, k is the Boltzmann constant and T is the temperature in degrees Kelvin.
This reaction was studied over the temperature range 430 to 633 C and over the pressure range 0.2 to 1.7 Torr. It was found that within this range, A has a value of approximately 5 x 105 ##and A E is equal to 0.91 eWmole. Equations similar to equation (2) describe the reactions occurring in the SiH4/NO and
SiH4/N2 systems, but of course, the values of A and A
E in these equations will be different from the values given above for the SiH4/N2O4 reaction.
Figure 3 shows schematically a simple apparatus which was used to detect pin-holes in the deposited silica layers. A steel container 31 has a floor 32 which is recessed on its inside face so as to accommodate a silicon slice 9 bearing a silica layer 33. Before the slice 9 was placed on the floor 32 of the container 31, the silica on one main surface of the slice 9 was removed by etching with hydrofluoric acid. A quantity of methanol 34 was placed in the container 31. A grid electrode 35 insulated from the container 31 by means of an annular member 36 was immersed in the methanol 34 and extended parallel to the surface of the silica layer 33. A transparent cover 37 was placed on a ledge 38 on the collar 36.A direct current bias of 40 volts was established between the grid 35 and the slice 9, and this produced a source 39 of hydrogen bubbles emanating from each pinhole in the silica layer 33. The pinhole density of the layer 33 was determined by counting the sources 39 of hydrogen bubbles over a given area using a travelling microscope 40.
Example 1
76 mm diameter polished silicon substrates 9 were loaded into a silica jig 10, the major surfaces of the slices 9 extended vertically, the inter-slice spacing being 5 mms. The jig 10 was loaded into the furnace tube 1, the door 11 was closed and the slices 9 were heated to 465by. The pressure in the tube 1 was then reduced to 10.2 Torr (measured by means of the Balzer gauge), the pumping speed of the pumping system was reduced while 5 litres per minute of argon was introduced into the tube 1 until the pressure in the tube 1 had risen to above 100 Torr.
The argon supply was stopped, and the pumping system was operated at full pumping speed until the pressure in the tube had fallen to 10.2 Torr. This purging procedure was performed twice more so as to remove residual-gaseous impurities from the apparatus. The pressure in the tube 1 was then adjusted to 1.0 Torr by adjusting the valve 17 whereby a suitable flowrate of efficiency-spoiling gas (nitrogen or argon) is fed into the throat of the
Roots blower 6through the gas supply line 18. The pressure in the tube 1 was maintained at 1.0 Torr throughout the deposition process with the aid of the control valve 17.
50 mis per minute of dinitrogen tetroxide was then introduced into the tube 1 from the source 13 and 50 mis per minute of silane was vented to waste from the source 12. After a period of 4 minutes to allow stabilisation of flows, the silane flow was discharged into the tube 1 whereupon deposition of silica formed commenced and was continued for 100 minutes. It was subsequently found that the silica layers deposited on the silicon substrate were 0.5 #m thick and had fewer than 0.5 pin-holes per sq. cm.
After the required time, the silane and dinitrogen tetroxide flows were discontinued and were replaced by 250 mis per minute of argon. After a further 4 minutes, pumping was stopped, and argon was passed into the tube 1 until pressure in the tube 1 had reached atmospheric pressure. The door 11 was then opened, and the jig 10 was removed from the tube 1.
Example 2
Silica layers were deposited on silicon slices from a reaction mixture consisting of 50 mis per minute of silane and 200 mis per minute of nitric oxide using a deposition temperature of 650 C. The tube 1 was purged and operated in a similar manner to that described in Example 1. Deposition was conducted for 100 minutes and it was found that the silica layers deposited were 0.5 #m thick. The incidence of pin-holes in these layers measured by means of the apparatus described with reference to Figure 3 was less than 0.5 per sq. cm.
Claims (8)
1. A method of making a semiconductor device, the method including the step of producing a silicon dioxide layer on a semiconductor substrate by heating a gas mixture comprising silane and/or dichlorosilane (SiH2Cl2) together with nitric oxide and/or dinitrogen tetroxide at a pressure below 20
Torr and at a temperature below 7500C in a reaction vessel containing the semiconductor substrate.
2. A method as claimed in Claim 1, wherein the gas mixture contains argon or nitrogen as a diluent.
3. A method as claimed in Claim 1 or Claim 2, wherein the gas mixture contains hydrogen chloride.
4. A method as claimed in any preceding Claim, wherein the gas mixture is formed by mixing silane and/or dichlorosilane with nitrogen dioxide-and/or dinitrogen tetroxide, said gas mixture being heated at a temperature in the range from 400 to 550"C.
5. A method as claimed in any of Claims 1 to 3, wherein the gas mixture comprises nitric oxide together with silane and,or dichlorosilane, said gas mixture being heated at a temperature between 600 and 750on.
6. A method as claimed in any preceding Claim, wherein the gas mixture contains a dopant, and the silicon dioxide layer produced is a doped silicon dioxide layer.
7. A method of making a semiconductor device, substantially as herein described with reference to the drawing and with reference to Example 1 or to
Example 2.
8. A semiconductor device manufactured by a method as claimed in any preceding Claim.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8029199A GB2061243B (en) | 1979-09-12 | 1980-09-10 | Method of making semiconductor devices |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7931618A GB2058731A (en) | 1979-09-12 | 1979-09-12 | Method of making semiconductor devices |
GB8029199A GB2061243B (en) | 1979-09-12 | 1980-09-10 | Method of making semiconductor devices |
Publications (2)
Publication Number | Publication Date |
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GB2061243A true GB2061243A (en) | 1981-05-13 |
GB2061243B GB2061243B (en) | 1983-05-18 |
Family
ID=26272847
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8029199A Expired GB2061243B (en) | 1979-09-12 | 1980-09-10 | Method of making semiconductor devices |
Country Status (1)
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GB (1) | GB2061243B (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0289246A1 (en) * | 1987-04-27 | 1988-11-02 | Seiko Instruments Inc. | Method of manufacturing MOS devices |
EP0470661A1 (en) * | 1990-08-06 | 1992-02-12 | Koninklijke Philips Electronics N.V. | Method of providing a silicion dioxide layer on a substrate by means of chemical reaction from the vapour phase at a low pressure (LPCVD) |
WO2000063958A1 (en) * | 1999-04-16 | 2000-10-26 | Advanced Micro Devices, Inc. | In situ, controlled ambient deposition of ono for application to flash eprom |
EP1160838A2 (en) * | 2000-05-31 | 2001-12-05 | Tokyo Electron Limited | Heat treatment system and method |
WO2017207940A1 (en) * | 2016-06-02 | 2017-12-07 | Sgd S.A. | Process for forming a barrier coating at the surface of a container and related facility |
-
1980
- 1980-09-10 GB GB8029199A patent/GB2061243B/en not_active Expired
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0289246A1 (en) * | 1987-04-27 | 1988-11-02 | Seiko Instruments Inc. | Method of manufacturing MOS devices |
EP0470661A1 (en) * | 1990-08-06 | 1992-02-12 | Koninklijke Philips Electronics N.V. | Method of providing a silicion dioxide layer on a substrate by means of chemical reaction from the vapour phase at a low pressure (LPCVD) |
WO2000063958A1 (en) * | 1999-04-16 | 2000-10-26 | Advanced Micro Devices, Inc. | In situ, controlled ambient deposition of ono for application to flash eprom |
EP1160838A2 (en) * | 2000-05-31 | 2001-12-05 | Tokyo Electron Limited | Heat treatment system and method |
EP1160838A3 (en) * | 2000-05-31 | 2004-12-01 | Tokyo Electron Limited | Heat treatment system and method |
US6863732B2 (en) | 2000-05-31 | 2005-03-08 | Tokyo Electron Limited | Heat treatment system and method |
WO2017207940A1 (en) * | 2016-06-02 | 2017-12-07 | Sgd S.A. | Process for forming a barrier coating at the surface of a container and related facility |
FR3052161A1 (en) * | 2016-06-02 | 2017-12-08 | Sgd Sa | METHOD FOR FORMING A BARRIER COATING ON THE SURFACE OF A CONTAINER AND RELATED INSTALLATION |
Also Published As
Publication number | Publication date |
---|---|
GB2061243B (en) | 1983-05-18 |
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