CN104152850A - Preparation method of doped-type porous SiCOH film with low dielectric constant - Google Patents

Preparation method of doped-type porous SiCOH film with low dielectric constant Download PDF

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Publication number
CN104152850A
CN104152850A CN201410315333.3A CN201410315333A CN104152850A CN 104152850 A CN104152850 A CN 104152850A CN 201410315333 A CN201410315333 A CN 201410315333A CN 104152850 A CN104152850 A CN 104152850A
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dielectric constant
dmcps
low dielectric
preparation
film
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CN201410315333.3A
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叶超
廖良生
袁大星
王响英
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Suzhou University
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Suzhou University
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Abstract

The invention discloses a preparation method of a doped-type porous SiCOH film with a low dielectric constant. The preparation method of the doped-type porous SiCOH film with a low dielectric constant is characterized in that DMCPS is taken as a precursor, a weakly polarized element or at least one group of CH4 and CHF3 is taken as a doping source, and an electron cyclotron resonance plasma method is adopted for preparing the film. The key point of the preparation method of the doped-type porous SiCOH film with a low dielectric constant is that a doping source containing a weakly polarized element or group is doped into the precursor; as the doped large-size CHx group or weakly polarized F atom can effectively reduce the dielectric constant, the finally obtained film with a low dielectric constant can have appropriate porosity and also has good film characteristics.

Description

A kind of preparation method of the porous SiC OH low dielectric constant films that adulterates
Technical field
The present invention relates to a kind of preparation method of the porous SiC OH low dielectric constant films that adulterates.
Background technology
For solve due to large-scale integrated circuit integrated level improve bring such as RC signal delay, power consumption, the series of problems such as crosstalk, porous low dielectric constant and ultra-low dielectric constant material attract wide attention.In the research of porous low dielectric constant and ultra-low dielectric constant material, because the porous SiCOH ultra-low-k film that adopts plasma reinforced chemical vapour deposition method (PECVD) to prepare has superior performance, and its specific inductivity has expanded to ultralow k scope, and is considered to very promising ultra-low dielectric constant material film.
As everyone knows, the method that reduces film k value mainly contains two kinds: the one, in thin-film material, introduce cavernous structure to reduce the density of thin-film material, and this can be by adopting the presoma of ring texture or mixing other labile group that is heated; The 2nd, to mixing the more intense element of electronegativity or group in thin-film material to reduce the polarization of thin-film material, such as introducing Si-F key.But, owing to introducing after cavernous structure, high porosity can cause the problems such as mechanical stability is bad, metal diffusing in integrating process, so porosity for increase film that can be suitable, can guarantee good film characteristics again, by introducing weak polarization key, combine and become a kind of important method of preparing low-k SiCOH film with introducing cavernous structure.
Summary of the invention
The present invention seeks to: the preparation method that a kind of porous SiC OH low dielectric constant films that adulterates is provided, the doped source that the method contains weak polarization element or group by introducing can effectively reduce the specific inductivity of the film preparing, and can guarantee the existing suitable porosity of the film finally obtaining simultaneously, have again good film characteristics.
Technical scheme of the present invention is: a kind of preparation method of the porous SiC OH low dielectric constant films that adulterates, is characterized in that take that DMCPS epoxy/organosilicon alkane is presoma, to contain the CH of weak polarization element or group 4, CHF 3in at least one as doped source, adopt Ecr plasma method to prepare film.
Further, above-mentioned preparation method of the present invention, its concrete steps are as follows:
(1) provide a silicon substrate, the column criterion of going forward side by side is cleaned;
(2) presoma DMCPS epoxy/organosilicon (purity >=99%) is put into the thermostatic evaporator of 80 ℃, using argon gas or nitrogen as carrier gas by gasification after DMCPS epoxy/organosilicon by gaseous source transmission pipeline, bring in the cavity of Ecr plasma equipment;
(3) by doped source CH 4or CHF 3by another gas circuit, introduce cavity, or by doped source CH 4and CHF 3by another two-way gas circuit, introduce cavity, keeping total flow rate of DMCPS+ argon gas or nitrogen is 10-20sccm, CH simultaneously 4the flow rate ratio of/DMCPS is controlled at not higher than 0.33, CHF 3the flow rate ratio of/DMCPS is controlled at not higher than 0.4;
(4) regulate the controller of Ecr plasma equipment to produce Ecr plasma, utilize downstream plasma by step 2) presoma and step 3) doped source decompose, at silicon chip surface, deposit the porous SiC OH low dielectric constant films that obtains adulterating, the thickness of film is 200～800nm; The change in magnetic field is by regulating the electric current I of two coils 1, I 2control I 1, I 2keep 150A, 130A constant; The power of microwave incident is 300W, and reflective power is less than 3%;
(5) doping porous SiC OH low dielectric constant films deposition being obtained carries out vacuum heat treatment in position, and annealing temperature is controlled at 300～500 ℃, soaking time 2～5 hours.
Further, in above-mentioned preparation method of the present invention, the throughput ratio of described DMCPS epoxy/organosilicon and argon gas or nitrogen remains on 3～8:1, and total flow rate of gas is controlled at 15sccm.
Further, in above-mentioned preparation method of the present invention, described step 2) gaseous source transmission pipeline described in is heated to 80～100 ℃ and remains unchanged, in order to prevent that DMCPS epoxy/organosilicon from liquefying in transmitting procedure.
Further, in above-mentioned preparation method of the present invention, before thin film deposition, base vacuum is 1 * 10 -3pa, during deposit film, air pressure is 0.1Pa.
Further, in above-mentioned preparation method of the present invention, the silicon substrate in described step (1) adopts the N-shaped low-resistance single crystal silicon substrate of (100) orientation.
Advantage of the present invention is:
(1) this preparation method provided by the invention, its core is in presoma, to mix the doped source that contains weak polarization element or group, adopts electron cyclotron resonace downstream plasma body method to prepare film.Before doping, dielectric constant values minimum is 2.88, and mixes CH in presoma 4after, the doping porous SiC OH low dielectric constant films preparing is owing to mixing large-sized CH xgroup, its k value is lowered to 2.45; When mix CHF in presoma 3time, the described film preparing is owing to mixing the F atom of weak polarization, and its k value can be reduced to 2.48.Therefore, the inventive method and the doping techniques relying on thereof can reduce the specific inductivity of film effectively, thereby obtain compared with the film of low-k.
(2) presoma is introduced cavity by different gas circuits respectively from doped source, and the ratio of doping is easy to control.
(3) presoma and doped source are to adulterate under electron cyclotron resonace downstream plasma condition, have avoided high pressure or high-octane condition.
(4) by this method, introduce the more intense element of electronegativity or group, effectively fallen the specific inductivity of low film.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described:
Fig. 1 is with CH in the present invention 4the dielectric constant values of the film of preparing for doped source is with CH 4/ DMCPS flow rate is than the graph of a relation changing;
Fig. 2 be take DMCPS as presoma CH in the present invention 4the FTIR figure of the low dielectric constant films of preparing for doped source;
Fig. 3 is with CHF in the present invention 3for film prepared by doped source, its dielectric constant values is with CHF 3/ DMCPS flow rate is than the graph of a relation changing;
Fig. 4 be take DMCPS as presoma, with CHF in the present invention 3the FTIR figure of the low dielectric constant films of preparing for doped source.
Embodiment
Below the technical scheme in the embodiment of the present invention is described in detail, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, the every other embodiment that those of ordinary skills obtain under the prerequisite of not making creative work, belongs to the scope of protection of the invention.
Now in conjunction with specific embodiments a kind of preparation method who adulterates porous SiC OH low dielectric constant films of the present invention is illustrated.
(this example is comparative example to embodiment 1, wherein doped source CH 4with the flow rate ratio of DMCPS be 0)
The preparation method of this doping porous SiC OH low dielectric constant films that the present embodiment provides, it possesses following step:
(1) the N-shaped low-resistance single crystal silicon substrate of (100) orientation is provided, it is carried out to standard clear, be placed in Ecr plasma equipment;
(2) prepare DMCPS epoxy/organosilicon that purity is 98% as presoma, and DMCPS epoxy/organosilicon is put into the thermostatic evaporator of 80 ℃ be vaporized.Utilize argon gas as carrier gas, the DMCPS epoxy/organosilicon after gasification to be sent in the cavity of Ecr plasma equipment by the gaseous source transmission pipeline of 80 ℃, the DMCPS epoxy/organosilicon of gasification and the throughput ratio of argon gas remain on 6.5:1, and total gas (DMCPS+ argon gas) flow rate is controlled at 15sccm.
(3) meanwhile by doped source CH 4by another gas circuit, introduce cavity, controlled doping source CH 4with the flow rate ratio of DMCPS be 0.
(4) control the electric current I of two coils in Ecr plasma equipment 1and I 2be respectively 150A and 130A, the power of microwave incident is 300W, reflective power 3%.DMCPS epoxy/organosilicon and doped source CH 4form plasma body, concurrent solution estranged, under the effect of magnetic field force on silicon substrate formation of deposits doping porous SiC OH low dielectric constant films.Wherein, base vacuum is 0.001Pa, and deposition pressure is 0.1Pa.
(5) film deposition being obtained carries out vacuum heat treatment in position, and annealing temperature is controlled at 450 ℃, soaking time 4 hours.
Embodiment 2
The present embodiment difference from Example 1 is, controlled doping source CH 4with the flow rate ratio of DMCPS be 0.08, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 3
The present embodiment difference from Example 1 is, controlled doping source CH 4with the flow rate ratio of DMCPS be 0.17, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 4
The present embodiment difference from Example 1 is, controlled doping source CH 4with the flow rate ratio of DMCPS be 0.25, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 5
The present embodiment difference from Example 1 is, controlled doping source CH 4with the flow rate ratio of DMCPS be 0.33, other are identical with embodiment 1, no longer carry out repeated description herein.
Known in conjunction with Fig. 1, for CH xthe low-k SiCOH film of doping, along with flow rate increases, specific inductivity reduces gradually.Work as CH 4/ DMCPS flow rate is than R=0.33 (CH 4flow rate be 2.0sccm) time, the minimum 2.45. that reaches of specific inductivity
As shown in Figure 2, along with CH 4the increase of flow rate, CH xthe composition of group obviously increases, after 450 ℃ of annealing 4 as a child, at 3000-2800cm -1cH in scope xthe intensity at peak does not significantly change.This result shows CH xgroup has been doped in film, still highly stable under the condition of thermal annealing.
Embodiment 6
The present embodiment difference from Example 1 is, by doped source CH 4change CHF into 3, and CHF 3be controlled at 0.1 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 7
The present embodiment difference from Example 1 is, by doped source CH 4change CHF into 3, and CHF 3be controlled at 0.2 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 8
The present embodiment difference from Example 1 is, by doped source CH 4change CHF into 3, and CHF 3be controlled at 0.28 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 9
The present embodiment difference from Example 1 is, by doped source CH 4change CHF into 3, and CHF 3be controlled at 0.36 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 10
The present embodiment difference from Example 1 is, by doped source CH 4change CHF into 3, and CHF 3be controlled at 0.4 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Shown in Fig. 3, for the low-k SiCOH film of F doping, along with CHF 3the increase of flow rate, the dielectric constant values of film first increases rear reduction, and minimum value can reach 2.48.
As shown in Figure 4, work as CHF 3/ DMCPS flow rate during than R=0, only has Si-O and CH in film xgroup.Along with CHF 3the increase of doping content, Si-O-Si, Si-O and C-H 3group composition reduces, and has occurred Si-OH, H-OH, C=C, C-F xwith Si-F group.Due to S-O cage shape and C-H 3divide the minimizing of subconstiuent and mixing of a small amount of F, the OH group that weak polarization key is polarized is by force offset, and so just causes the increase of specific inductivity.Work as CHF 3/ DMCPS flow rate is increased at 0.40 o'clock than from R=0.28, can see C-F xobviously strengthen with Si-F peak.This doping that shows F in film increases.Therefore, exactly because being doped in film, F just caused specific inductivity to be reduced to 2.48 by 3.73.
Embodiment 11
The present embodiment difference from Example 1 is, the doped source of step (3) is except CH 4also increased CHF 3, and CH 4and CHF 3by two gas circuits, introduce cavity, wherein CH respectively 4be controlled at 0.3 with the flow rate ratio of DMCPS, and CHF 3be controlled at 0.35 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 12
The present embodiment difference from Example 1 is, the doped source of step (3) is except CH 4also increased CHF 3, and CH 4and CHF 3by two gas circuits, introduce cavity, wherein CH respectively 4be controlled at 0.33 with the flow rate ratio of DMCPS, and CHF 3be controlled at 0.4 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
Embodiment 13
The present embodiment difference from Example 1 is, the doped source of step (3) is except CH 4also increased CHF 3, and CH 4and CHF 3by two gas circuits, introduce cavity, wherein CH respectively 4be controlled at 0.17 with the flow rate ratio of DMCPS, and CHF 3be controlled at 0.28 with the flow rate ratio of DMCPS, other are identical with embodiment 1, no longer carry out repeated description herein.
In sum, the present invention proposes a kind of doping techniques of new low dielectric constant material film, it is characterized in that mixing the doped source that contains weak polarization element or group in presoma, adopt electron cyclotron resonace downstream plasma body method to prepare film.Presoma is introduced cavity by different gas circuits respectively from doped source, and the ratio of doping is easy to control; Presoma and doped source are to adulterate under electron cyclotron resonace downstream plasma condition, have avoided high pressure or high-octane condition; By this method, introduce the more intense element of electronegativity or group, effectively fallen the specific inductivity of low film.
To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned one exemplary embodiment, and in the situation that not deviating from spirit of the present invention or essential characteristic, can realize the present invention with other specific form.Therefore, no matter from which point, all should regard embodiment as exemplary, and be nonrestrictive, scope of the present invention is limited by claims rather than above-mentioned explanation, is therefore intended to include in the present invention dropping on the implication that is equal to important document of claim and all changes in scope.
In addition, be to be understood that, although this specification sheets is described according to embodiment, but not each embodiment only comprises an independently technical scheme, this narrating mode of specification sheets is only for clarity sake, those skilled in the art should make specification sheets as a whole, and the technical scheme in each embodiment also can, through appropriately combined, form other embodiments that it will be appreciated by those skilled in the art that.

Claims (6)

1. the adulterate preparation method of porous SiC OH low dielectric constant films, is characterized in that take that DMCPS epoxy/organosilicon alkane is presoma, to contain the CH of weak polarization element or group 4, CHF 3in at least one as doped source, adopt Ecr plasma method to prepare film.
2. the preparation method of a kind of porous SiC OH low dielectric constant films that adulterates according to claim 1, is characterized in that concrete steps are as follows:
(1) provide a silicon substrate, the column criterion of going forward side by side is cleaned;
(2) purity is more than or equal to 99% presoma DMCPS epoxy/organosilicon and puts into the thermostatic evaporator of 80 ℃, using argon gas or nitrogen as carrier gas, the DMCPS epoxy/organosilicon after gasification to be brought in the cavity of Ecr plasma equipment by gaseous source transmission pipeline;
(3) by doped source CH 4or CHF 3by another gas circuit, introduce cavity, or by doped source CH 4and CHF 3by another two-way gas circuit, introduce cavity, keeping total flow rate of DMCPS+ argon gas or nitrogen is 10-20sccm, CH simultaneously 4the flow rate ratio of/DMCPS is controlled at not higher than 0.33, CHF 3the flow rate ratio of/DMCPS is controlled at not higher than 0.4;
(4) regulate the controller of Ecr plasma equipment to produce Ecr plasma, utilize downstream plasma by step 2) presoma and step 3) doped source decompose, at silicon chip surface, deposit the porous SiC OH low dielectric constant films that obtains adulterating, the thickness of film is 200～800nm; The change in magnetic field is by regulating the electric current I of two coils 1, I 2control I 1, I 2keep 150A, 130A constant; The power of microwave incident is 300W, and reflective power is less than 3%;
(5) doping porous SiC OH low dielectric constant films deposition being obtained carries out vacuum heat treatment in position, and annealing temperature is controlled at 300～500 ℃, soaking time 2～5 hours.
3. the preparation method of a kind of porous SiC OH low dielectric constant films that adulterates according to claim 2, is characterized in that the throughput ratio of DMCPS epoxy/organosilicon and argon gas or nitrogen remains on 3～8:1, and total flow rate of gas is controlled at 15sccm.
4. the preparation method of a kind of porous SiC OH low dielectric constant films that adulterates according to claim 2, it is characterized in that described step 2) described in gaseous source transmission pipeline be heated to 80～100 ℃ and remain unchanged, in order to prevent that DMCPS epoxy/organosilicon from liquefying in transmitting procedure.
5. the preparation method of a kind of porous SiC OH low dielectric constant films that adulterates according to claim 2, is characterized in that before thin film deposition, and base vacuum is 1 * 10 -3pa, during deposit film, air pressure is 0.1Pa.
6. the preparation method of a kind of porous SiC OH low dielectric constant films that adulterates according to claim 2, is characterized in that the N-shaped low-resistance single crystal silicon substrate that the silicon substrate in described step (1) adopts (100) to be orientated.
CN201410315333.3A 2014-07-03 2014-07-03 Preparation method of doped-type porous SiCOH film with low dielectric constant Pending CN104152850A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01246357A (en) * 1988-03-28 1989-10-02 Mitsubishi Heavy Ind Ltd Production of cubic boron nitride film
CN103526179A (en) * 2013-10-30 2014-01-22 苏州大学 Porous low-permittivity thin film material and preparation method thereof
CN103531463A (en) * 2013-10-30 2014-01-22 苏州大学 Preparation method of low surface pore and low dielectric constant thin-film material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01246357A (en) * 1988-03-28 1989-10-02 Mitsubishi Heavy Ind Ltd Production of cubic boron nitride film
CN103526179A (en) * 2013-10-30 2014-01-22 苏州大学 Porous low-permittivity thin film material and preparation method thereof
CN103531463A (en) * 2013-10-30 2014-01-22 苏州大学 Preparation method of low surface pore and low dielectric constant thin-film material

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
YE CHAO ET AL.: "Effect of F- and CH- Doped on Dielectric Properties of SiCOH Films Deposited by Decamethylcyclopentasiloxane Electron Cyclotron Resonance Plasma", 《CHIN.PHYS.LETT》 *
叶超: "SiCOH低k薄膜的ECR等离子体沉积与介电性能研究", 《中国优秀博士学位论文全文数据库 基础科学辑（月刊）》 *

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Application publication date: 20141119