CN103426741A - Method for improving uniformity of thickness of side wall spacing nitride of gate electrode - Google Patents
Method for improving uniformity of thickness of side wall spacing nitride of gate electrode Download PDFInfo
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- CN103426741A CN103426741A CN2013103392217A CN201310339221A CN103426741A CN 103426741 A CN103426741 A CN 103426741A CN 2013103392217 A CN2013103392217 A CN 2013103392217A CN 201310339221 A CN201310339221 A CN 201310339221A CN 103426741 A CN103426741 A CN 103426741A
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Abstract
The invention relates to a method for improving the uniformity of the thickness of side wall spacing nitride of a gate electrode. The method is applied to a semiconductor structure which is formed after polycrystalline silicon is etched in a gate electrode process, and the semiconductor structure comprises a gate-oxide layer and the polycrystalline silicon gate electrode which covers the gate-oxide layer. The method includes manufacturing the side wall spacing nitride on the surface of the semiconductor structure by an atom layer deposition process. The method has the advantages that the thickness of a silicon nitride film can be controlled accurately, the thickness repeatability is high, a step coverage rate is perfect, and the thermal budget can be reduced.
Description
Technical field
The present invention relates to a kind of semiconductor preparing process method, relate in particular to a kind of method of improving grid curb wall spacer nitride thing even thickness degree.
Background technology
At present, for the preparation technology of grid electrode of semiconductor lateral wall partitioning nitride, roughly can be divided into two kinds, the first is to adopt traditional boiler tube DCS-NH
3Technique, and another kind is to adopt single chamber high temperature nitrogen compound (Single Chamber Nitride) technique.
Adopt at present traditional boiler tube DCS-NH
3The preparation of carrying out nitride normally passes into reacting gas and is reacted in boiler tube, and its reaction temperature is greatly about 650～770 ℃, and ambient pressure is at 0.25～0.35torr, and its reaction principle can be expressed as by reaction equation: 3SiH
2Cl
2+ 10NH
3→ Si
3N
4+ 6NH
4Cl+6H
2, the even thickness degree that reacts prepared film by this is generally in 2%～4% left and right.And the preparation that adopts single chamber high temperature nitrogen compound (Single Chamber Nitride) technique to carry out nitride is to pass into reacting gas reacted and generate nitride film in reaction chamber, its reaction temperature is greatly about 710 ℃ of left and right, ambient pressure is at 200～300torr, and its reaction principle can be expressed as 3SiH by reaction equation
4+ 4NH
3→ Si
3N
4+ 12H
2, the even thickness degree that reacts prepared film by this is generally in 6% left and right.
Fig. 1 prepares the pattern of grid curb wall spacer nitride thing and the contrast schematic diagram of desirable pattern by traditional handicraft, as we can see from the figure, the side wall part of the silicon nitride film 1 prepared by conventional method is thinner with respect to top section, and with the silicon nitride film 2 under desirable covering state, compare, it presents pattern in uneven thickness.Visible, the uniformity of the currently used prepared nitride film of method for preparing grid curb wall spacer nitride thing is poor, be mainly reflected in following two aspects and this uniformity is poor: one is that even thickness degree in same silicon chip is poor and step coverage is poor; Its two, be that the even thickness degree between different silicon chips is poor.In addition, because current preparation technology's temperature is all higher, all more than 600 ℃, so can cause heat budget also higher.
Chinese patent (CN1706984A) discloses a kind of formation method of silicon nitride layer, and this formation method is that deposition boiler tube first is provided, and this deposition boiler tube comprises outer tube, brilliant boat, air injector and gas uniform injection device.Wherein brilliant boat is configured in outer tube inside, in order to sink to most wafers.In addition, air injector is between outer tube and brilliant boat.In addition, gas injection apparatus between outer tube and brilliant boat, and the gas that the gas uniform injection device is exported thus can be uniformly distributed with deposition boiler tube in.Then, the silicon containing gas body source is delivered in deposition boiler tube by air injector, and the nitrogenous gas source that will be mixed with carrier gas is by gas uniform injection device delivery value deposition boiler tube, with at crystal column surface cvd nitride silicon thin film.
The disclosed method of this patent is the technique that traditional boiler tube prepares silicon nitride film, it just adopts even injection device to be exported in the second gas less to gas flow passes into the process in boiler tube, therefore, the method is improved limited to the uniformity of the silicon nitride film of preparation.
Chinese patent (CN1755898A) disclose a kind of on wafer the manufacture method of cvd nitride silicon thin film.At first one chemical gas-phase deposition system is provided, it comprises the tubulose boiler tube, be connected at least BTBAS supply line at the pedestal position of this boiler tube, be connected to the boiler tube upper end outlet line, be connected the bypass line of BTBAS process pipelines and outlet line, and the vacuum pump that is connected outlet line, wherein bypass line is the cut-out closed condition; By in the wafer placement and the interior tube body in boiler tube of one batch; Pass into nitrogenous gas in interior tube body; Pass into predecessor BTBAS gas via the BTBAS supply line, and vacuum pump maintains pressure in the interior tube body low pressure range at 0.1Torr to 3Torr in this interior tube body; Carry out the silicon nitride film deposition reaction in interior tube body, with silicon nitride film on wafer surface; When the silicon nitride film deposition reaction finishes, close with being about to the cut-out of BTBAS supply line, and open bypass line immediately; And the wafer that shifts out this batch.
In this patent, disclosed method is to adopt chemical vapour deposition technique to carry out the preparation of silicon nitride film, it is only by cut off immediately the supply line of BTBAS after reaction, to avoid predecessor BTBAS gas to continue to enter into this boiler tube, thereby improve particle issues.Do not mention measure and method how to improve film equality in this patent.
Summary of the invention
In view of the above problems, the invention provides a kind of method of improving grid curb wall spacer nitride thing even thickness degree.
The technical scheme that technical solution problem of the present invention adopts is:
A kind of method of improving grid curb wall spacer nitride thing even thickness degree, in the semiconductor structure that is applied to form after the etching polysilicon in grid technology, described semiconductor structure comprises grid oxide layer and be covered in the polysilicon gate on described grid oxide layer, and wherein, described method comprises:
Adopt atomic layer deposition technique to prepare the lateral wall partitioning nitride of described semiconductor structure in the surface of described semiconductor structure.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, described nitride is silicon nitride.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, described method also comprises:
One boiler tube is provided;
Described semiconductor structure is placed in to described boiler tube;
Pass into successively NH in described boiler tube
3Gas, N
2Gas, DCS gas, N
2Gas, form one deck silicon nitride film with the surface at described semiconductor structure.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, the ambient temperature in described boiler tube is 450～550 ℃.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, by the described NH that passes into successively
3Gas, N
2Gas, DCS gas, N
2The technique initialization of gas is a process cycle.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, control the thickness of described silicon nitride film by the quantity of regulating described process cycle.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, when described grid is several, according to density and the depth-to-width ratio between these several grids, by regulating the time length of described process cycle, to improve the step coverage of described silicon nitride film.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, be provided with the special air pipe of at least two porous in described boiler tube, two described special air pipes are carried respectively described NH
3Gas and described DCS gas enter in boiler tube.
The described method of improving grid curb wall spacer nitride thing even thickness degree, wherein, be provided with the pore that some spacings are equal on the special air pipe of described porous, and several described pores all are located along the same line.
Technique scheme has following advantage or beneficial effect:
The inventive method is by adopting atomic layer deposition technique to prepare grid curb wall spacer nitride thing, due to the silicon nitride film that adopts this technique can obtain to approach the monoatomic layer thickness of physics limit in a process cycle.Therefore, the inventive method has that the silicon nitride film THICKNESS CONTROL is accurate, the repeated high beneficial effect of thickness.There is again desirable step coverage and reduce heat budget simultaneously.
The accompanying drawing explanation
With reference to appended accompanying drawing, to describe more fully embodiments of the invention.Yet appended accompanying drawing only, for explanation and elaboration, does not form limitation of the scope of the invention.
Fig. 1 is the grid curb wall spacer nitride silicon pattern for preparing by traditional handicraft and the contrast schematic diagram between desirable pattern;
Fig. 2 is furnace tube structure schematic diagram of the present invention;
Fig. 3 is the enlarged diagram of the special air pipe structure of porous in boiler tube of the present invention;
Fig. 4～5th, the step cycle schematic diagram in the inventive method;
Fig. 6 forms the structural representation of silicon nitride film in the side wall technique of the low high breadth depth ratio of live width by the inventive method;
Fig. 7 forms the structural representation of silicon nitride film in common side wall technique by the inventive method.
Embodiment
The invention provides a kind of method of improving grid curb wall spacer nitride thing even thickness degree, can be applicable in the preparation technology of grid curb wall spacer nitride thing, to can be used for technology node be 65/55nm, 45/40nm, 32/28nm, be less than or equal in the technique of 22nm etc.; Can be applied to the technology platforms such as Logic, eFlash, CIS.
Main thought of the present invention is by adopting atomic layer deposition (Atom Layer Deposition, abbreviation ALD) method prepares the lateral wall partitioning nitride of grid, due to atomic layer deposition be by material with monatomic form membrane in layer be plated in substrate surface, therefore, the lateral wall partitioning nitride that adopts the atomic layer deposition method to prepare grid can accurately be controlled the thickness of prepared nitride, make film have fabulous step coverage, the even thickness degree between silicon chip inside and different silicon chips is good simultaneously; In addition, because the reaction temperature of atomic layer deposition is relatively low, so the heat budget of device is also lower.
The inventive method need to be prepared with boiler tube the technique of grid curb wall spacer nitride thing, special air pipe in traditional boiler tube is all to adopt the single hole pipeline, the single hole pipeline is owing to only arranging one for sending the pore of reacting gas on the pipeline of gas communication, therefore, reacting gas can only enter in boiler tube and be reacted from this pore, when gas from this pore enters boiler tube, restriction due to the diffusion effect of gas, the distribution of gas in boiler tube inside is inhomogeneous, reacting gas concentration near pore is greater than other local gas concentrations in boiler tube, the silicon chip that will cause like this zones of different in boiler tube is different due to the distance at a distance of special air pipe pore separately, therefore, reacting gas concentration in its residing environment is also different, and then cause the poor problem of even thickness degree between the silicon silicon chip.
Therefore, at first provide in the present invention a boiler tube after improvement, this boiler tube and traditional boiler tube institute difference are, special air pipe in this boiler tube is not the design that adopts single hole, but there are the identical a plurality of pores in interval, as shown in Figure 3, these pores 301 are distributed on the same straight line.Fig. 2 is the structural representation of the boiler tube in invention, as shown in Figure 2, there are two in this boiler tube for the special air pipe of the porous that passes into reacting gas, comprising the special air pipe 201 of the first porous and the special air pipe 202 of the second porous, when reaction, in the special air pipe of two porous, pass into respectively the special gas of different reactions, be provided with a radio frequency electrode 203 between these two special air pipes, the pore (in the drawings do not illustrate) of the special gas of reaction from pipeline in the special air pipe 201 of the first porous enters in boiler tube, after in entering boiler tube, at first through radio frequency electrode, 203 effects are activated, make the first reacting gas there is certain activation energy, then, the first reacting gas be activated is reacted to form required film on silicon chip with the second reacting gas passed into by the special air pipe 202 of the second reaming, simultaneous reactions also can generate certain accessory substance, these accessory substances are discharged from boiler tube by the exhaust apparatus 204 in boiler tube.
Below in conjunction with specific embodiment, the inventive method is elaborated.
The preparation that adopts in the present embodiment a boiler tube with the special air pipe of porous to adopt atomic layer deposition technique to prepare grid curb wall spacer nitride thing, adopt respectively presoma NH in the present embodiment
3With presoma DCS(dichloro-dihydro silicon, claim again dichlorosilane, molecular formula: H
2Cl
2Si) as the special gas of the first reaction and the special gas of the second reaction.
At first, the substrate that provides a surface to be prepared with grid, this grid can comprise the grid oxide layer after etching and be covered in the polysilicon on this grid oxide layer, then this substrate is implanted in boiler tube, in the first special air pipe of boiler tube, passes into presoma NH
3Gas, after this gas enters the first special air pipe, the some pores from being distributed in the first special air pipe enter in boiler tube, when this gas enters in boiler tube at first by the in-situ radio-frequency electrode activation, under the effect of this electrode, generate NH
3Active group, this active group can reduce load effect (loading effect) in subsequent reactions prepares the process of silicon nitride film.Now, this active group is maintained at the surface of silicon chip.
Then, pass into the gas that stability is higher in boiler tube boiler tube is carried out to purge, can preferably adopt N
2.
When adopting N
2After the reaction boiler tube purge, pass into presoma DCS gas in the second special air pipe of boiler tube, after this gas enters the second special air pipe, some pores from being distributed in the second special air pipe enter in boiler tube, at this moment the second presoma reacts with the active group that is adsorbed in silicon chip surface, start to form gradually needed silicon nitride film by displacement, and produce corresponding accessory substance simultaneously, when surperficial active group is consumed fully, reaction just automatically stops and forming the atomic layer needed, and is completed into silicon nitride film.
Continuation passes into N in boiler tube
2Boiler tube is carried out to purge.
So far, can on silicon chip, deposit the about thickness of one deck by above-mentioned reactions steps is
Silicon nitride film, the temperature of above-mentioned reaction need be controlled at 450～550 ℃ (as 450 ℃, 500 ℃, 550 ℃ etc.), due to what adopt, is the standby silicon nitride film of atomic layer deposition legal system, therefore, the even thickness degree of formed film is better.
Further, can increase the thickness of prepared silicon nitride film by copying above-mentioned step, as shown in Figures 4 and 5, from NH
3Special gas passes into, to N
2The evolution purge, pass into to the special gas of DCS, finally arrives N again
2The evolution purge, this is the one-period for preparing grid curb wall spacer nitride silicon.Determine the required periodicity that carries out above-mentioned processing step according to the required thickness that makes silicon nitride film.For example, according to design, need the thickness of the grid curb wall spacer nitride silicon thin film of preparation to need 50nm, and if the prepared silicon nitride film thickness of each process cycle is
Need so to carry out the preparation technology in 500 cycles.
Further, in technical process with NH
3Special gas passes into the beginning (being the beginning in each cycle) for technique, in order to guarantee that the special gas of DCS can be reacted fully, through several week after date, when reaction finishes, guarantees also with NH simultaneously
3Special gas passes into the end into technique.
As shown in Fig. 6～7, Fig. 6 adopts the inventive method to form the structural representation of silicon nitride film in the side wall technique of the low high breadth depth ratio of live width, and Fig. 7 adopts the inventive method to form the structural representation of silicon nitride film in common side wall technique.As can be seen from the figure, the thickness of the top of grid, middle part and bottom is all basically identical.As can be seen here, the grid curb wall spacer nitride silicon prepared by the inventive method in common grid curb wall technique or the step coverage in the side wall technique of low live width high-aspect-ratio nearly all close to 100%.
Further, by the quality that can improve prepared silicon nitride film action time of suitable raising reaction temperature or increase in-situ radio-frequency electrode.
In sum, adopt the boiler tube in this and use the prepared grid curb wall spacer nitride of the method silicon thin film in the present invention to there is the good uniformity, its step coverage is also better simultaneously, in addition, reaction temperature during due to the atomic layer deposition technique in the inventive method is lower, therefore can be so that the corresponding reduction of heat budget.
For a person skilled in the art, after reading above-mentioned explanation, various changes and modifications undoubtedly will be apparent.Therefore, appending claims should be regarded whole variations and the correction of containing true intention of the present invention and scope as.In claims scope, scope and the content of any and all equivalences, all should think and still belong to the intent and scope of the invention.
Claims (9)
1. a method of improving grid curb wall spacer nitride thing even thickness degree, in the semiconductor structure that is applied to form after the etching polysilicon in grid technology, described semiconductor structure comprises and it is characterized in that grid oxide layer and be covered in the polysilicon gate on described grid oxide layer, and described method comprises:
Adopt atomic layer deposition technique to prepare the lateral wall partitioning nitride of described semiconductor structure in the surface of described semiconductor structure.
2. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 1, is characterized in that, described nitride is silicon nitride.
3. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 2, is characterized in that, described method also comprises:
One boiler tube is provided;
Described semiconductor structure is placed in to described boiler tube;
Pass into successively NH in described boiler tube
3Gas, N
2Gas, DCS gas, N
2Gas, form one deck silicon nitride film with the surface at described semiconductor structure.
4. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 3, is characterized in that, the ambient temperature in described boiler tube is 450～550 ℃.
5. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 3, is characterized in that, by the described NH that passes into successively
3Gas, N
2Gas, DCS gas, N
2The technique initialization of gas is a process cycle.
6. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 5, is characterized in that, controls the thickness of described silicon nitride film by the quantity of regulating described process cycle.
7. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 5, it is characterized in that, when described grid is several, according to density and the depth-to-width ratio between these several grids, by regulating the time length of described process cycle, to improve the step coverage of described silicon nitride film.
8. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 3, is characterized in that, is provided with the special air pipe of at least two porous in described boiler tube, and two described special air pipes are carried respectively described NH
3Gas and described DCS gas enter in boiler tube.
9. the method for improving grid curb wall spacer nitride thing even thickness degree as claimed in claim 8, is characterized in that, on the special air pipe of described porous, is provided with the pore that some spacings are equal, and several described pores all are located along the same line.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030059535A1 (en) * | 2001-09-25 | 2003-03-27 | Lee Luo | Cycling deposition of low temperature films in a cold wall single wafer process chamber |
| US20040058556A1 (en) * | 2002-09-24 | 2004-03-25 | Samsung Electronics Co., Ltd. | Method of manufacturing a metal oxide semiconductor transistor |
| US20120220137A1 (en) * | 2011-02-28 | 2012-08-30 | Hitachi Kokusai Electric Inc. | Method of manufacturing semiconductor device and method of processing substrate and substrate processing apparatus |
| CN102737977A (en) * | 2011-03-31 | 2012-10-17 | 东京毅力科创株式会社 | Plasma-nitriding method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030059535A1 (en) * | 2001-09-25 | 2003-03-27 | Lee Luo | Cycling deposition of low temperature films in a cold wall single wafer process chamber |
| US20040058556A1 (en) * | 2002-09-24 | 2004-03-25 | Samsung Electronics Co., Ltd. | Method of manufacturing a metal oxide semiconductor transistor |
| US20120220137A1 (en) * | 2011-02-28 | 2012-08-30 | Hitachi Kokusai Electric Inc. | Method of manufacturing semiconductor device and method of processing substrate and substrate processing apparatus |
| CN102737977A (en) * | 2011-03-31 | 2012-10-17 | 东京毅力科创株式会社 | Plasma-nitriding method |
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