CN108250976A - A kind of chemical mechanical polishing liquid - Google Patents

Abstract

One aspect of the present invention provides a kind of chemical mechanical polishing liquid, and it includes water, the negatively charged abrasive grains in surface can generate the compound of silver ion, can generate the compound of sulfate ion, peroxide.The present invention significantly improves the stability of polishing fluid, further improves polishing stable degree, improves polishing efficiency, reduce polishing cost by changing the charge of abrasive grains silica surface.

Description

A kind of chemical mechanical polishing liquid

Technical field

The present invention relates to chemical mechanical polishing liquid field more particularly to a kind of chemically mechanical polishings for polishing metal tungsten Liquid.

Background technology

With the continuous development of semiconductor technology and being continuously increased for large scale integrated circuit interconnection layer, conductive layer and The planarization of insulating medium layer becomes particularly critical, wherein, the chemical machine initiated the eighties in twentieth century by IBM Corporation Tool polishing (CMP) technology is considered as the most efficient method of current global planarizartion.Chemically mechanical polishing (CMP) be it is a kind of by Chemical action, mechanism and both effects are combined and realize the technology of planarization；It is usually by one with polishing The grinding table of pad and a grinding head composition for being used to carry chip.Wherein grinding head fixes chip, then by chip just Face pressure is on polishing pad, when being chemically-mechanicapolish polished, grinding head on polishing pad linear movement or along with grinding table The same direction of motion rotation；At the same time, the slurries containing grinding agent are dripped on polishing pad, and because centrifugal action is laid in On polishing pad.Chip surface realizes global planarizartion under double action mechanically and chemically.

To chemical metal layer mechanical polishing (CMP) main mechanism be considered as：Oxidant first by oxidation on metal surface into Film is the grinding agent of representative by this layer of oxidation film mechanical removal using silica and aluminium oxide, generates new metal surface；It generates New metal surface continue to be aoxidized, both effect collaborations carry out.

As the tungsten of one of chemically mechanical polishing (CMP) object, at higher current densities, anti-electron transfer capabilities By force, and good Ohmic contact can be formed with silicon, so can be as contact hole and the filling metal of interlayer hole and diffusion resistance Barrier.

The chemically mechanical polishing (CMP) of tungsten at present, there are many method, such as：The potassium ferricyanide of the reports such as F.B.Kaufman is used In method (" Chemical Mechanical Polishing for Fabricating of tungsten CMP Patterned W Metal Features as Chip Interconnects ", Journal of the Electro Society, Vol.138, No.11,1991 years November of chemical), a kind of disclosed in United States Patent (USP) US5340370 be used for tungsten The formula of size of (CMP) is chemically-mechanicapolish polished, wherein containing the potassium ferricyanide and silica abrasive, is contained simultaneously as pH buffer Acetate.Since the potassium ferricyanide is under ultraviolet light or solar radiation and in acid medium, the hydrogen cyanogen of severe toxicity can be decomposited Acid, thus limit it and be widely used.

Chemical metal layer machine polishing liquor, United States Patent (USP) US006008119A are disclosed disclosed in United States Patent (USP) US5527423 Method of polishing semiconductor wafer and United States Patent (USP) US6284151 disclosed in tungsten CMP slurry etc. use Fe (NO₃)₃/ alumina system mechanically polishes (CMP) for tungsten.The polishing body ties up to static etch rate (static etch Rate) aspect has advantage, but since using aluminium oxide, as grinding agent, product defects (defect) aspect exists significantly not Foot.The ferric nitrate of high concentration causes the pH value of polishing fluid in highly acid simultaneously, severe corrosion equipment, meanwhile, generate iron rust, pollution Polishing pad.In addition to this, the iron ion of high concentration is as moveable metal ion, and seriously reduce semiconductor components and devices can By property.

Metal CMP polishing composition is used as catalyst, hydrogen peroxide using ferric nitrate disclosed in United States Patent (USP) US5958288 It is used as oxidant, carries out tungsten CMP, it should be noted that in that patent, it is noted that a variety of transition metal elements, It is confirmed in experiment and significantly effectively there was only ferro element, therefore the actual implementation effect and range of the invention are very limited.Though this method The dosage of ferric nitrate is so considerably reduced, but Fenton reactions occur between hydrogen peroxide since iron ion still has, Hydrogen peroxide can rapid and tempestuously decomposition failure, therefore the polishing fluid there are stability it is poor the problem of.

United States Patent (USP) US5980775 discloses rubbing paste disclosed in metal CMP polishing slurries and United States Patent (USP) US6068787 Material adds in organic acid and makees stabilizer, improve the decomposition rate of hydrogen peroxide, still on the basis of United States Patent (USP) US5958288 Hydrogen peroxide decomposition rate is still higher, and hydrogen peroxide concentration can reduce by more than 10% in usual two weeks, and polishing velocity is caused to decline, The gradual decomposition failure of polishing fluid.

Due to tungsten in the system of iron and hydrogen peroxide static corrosion speed quickly, directly influence the yield of production, thus Need the static corrosion inhibitor of further addition tungsten.As included inhibitor of tungsten etching disclosed in Chinese patent CN1326199C Polishing composition and the disclosed polishing compositions for including inhibitor of tungsten etching of CN1966594A, are catalyzed in hydrogen peroxide and iron The erosion inhibitor of tungsten is added in the system of agent, inhibits the corrosion of tungsten.

Wolfram polishing liquid, the cycles of concentration of the prior art be not high, because after improving cycles of concentration, the stability of formula can be substantially Decline, be in particular in abrasive particles increase, sedimentation, lose original polishing performance.In order to make tungsten in semiconductor technology Preferably application, people continuously attempt to the improvement of new polishing fluid.

Invention content

To solve the above problems, the present invention provides a kind of chemical mechanical polishing liquid, the polishing fluid is by changing abrasive grains The charge of silica surface significantly improves the stability of polishing fluid, further improves polishing stable degree, improves polishing effect Rate reduces polishing cost.

Specifically, one aspect of the present invention is to provide a kind of chemically mechanical polishing polishing fluid, and it includes water, surface are negatively charged The grinding agent of lotus, the compound that silver ion can be generated, the compound that sulfate ion can be generated, peroxide.

Wherein, preferably, the abrasive grains are at pH value 2~4 (including 2 and 4), surface band 30mv to 70mv is born The silica of charge.

Preferably, a concentration of 0.1~20wt% of the abrasive grains；Preferably, a concentration of the 0.5 of the abrasive grains ~6wt%.

Preferably, the negative electrical charge on the abrasive grains surface can be by silica and containing carboxyl or sulfonic silane It is obtained after coupling agent treatment.Preferably, the negative electrical charge on the abrasive grains surface can be by containing sulfonic silane coupling agent It is obtained after processing.

Preferably, the compound that can generate silver ion is silver sulfate, silver nitrate, silver fluoride and/or silver perchlorate It is one or more in soluble silver salt.

Preferably, a concentration of 0.001%~0.2wt% of the compound that silver ion can be generated.

Preferably, the compound that can generate sulfate ion is sulfate.Preferably, it is described can generate sulfate radical from The compound of son is one or more in nonmetallic sulfate.Preferably, the nonmetallic sulfate is ammonium sulfate.

Preferably, the compound concentration that can generate sulfate ion is 0.1%~0.3wt%.

Preferably, the peroxide is hydrogen peroxide.

Preferably, the peroxide concentrations are 0.1~5wt%；Preferably, the peroxide concentrations for 1~ 2wt%.

Preferably, the pH of the chemical mechanical polishing liquid is 2~4.

In addition, further include pH adjusting agent in the polishing fluid.

Another aspect of the present invention is to provide a kind of above-mentioned chemical mechanical polishing liquid answering in the polishing of tungsten With.

Specific embodiment

Selected raw material is all commercially available in the present embodiment, and all components are dissolved and are uniformly mixed, and quality is supplied with water Percentage is to 100%.It is adjusted with pH adjusting agent to desired pH, it is as follows to obtain specific embodiment.

1 comparative example of table and embodiment, which are matched, is when embodied result

The polishing fluid prepared in above-described embodiment 1~8 and comparative example is carried out to the chemically mechanical polishing of tungsten respectively, and will be thrown Light effect is compared.

Polishing condition：Polishing machine platform is Mirra, IC1010 polishing pads, grinding pressure 3psi, polishing fluid rate of addition 100ml/ minutes.

It is comparative example and the proportioning of embodiment and its specific implementation result in table 1.Wherein, comparative example 1 shows only to grind In the presence of agent and hydrogen peroxide, the polishing velocity of tungsten is very low；Comparative example 2 shows in the presence of iron ion and hydrogen peroxide are common, tungsten Polishing velocity can be obviously improved, but grinding agent (silica) is unstable, and average grain diameter increases by 5 nanometers in 3 days；3 table of comparative example It is bright, in the presence of iron ion and hydrogen peroxide are common, by the surface charge of abrasive silica to dropping to -30mv, grinding agent Stability is obviously improved, and average grain diameter wants 100 talentes to increase by 5 nanometers；Comparative example 4 shows：It can be generated with the system of silver ion The take-off speed of tungsten quickly, significant advantage are that polishing velocity is stablized, 21 talent's attenuation 10%.(iron-containing system is to decay for 3 days 10%).Shortcoming is that grinding agent (silica) stability is bad, and average grain diameter increases by 5 nanometers in 3 days.

And the embodiment of the present invention 1 shows：In argentiferous system, by the surface charge of abrasive silica to drop to- 30mv, grinding agent stability are obviously improved, and average grain diameter wants 110 talentes to increase by 5 nanometers.Polishing velocity and attenuation are still relatively steady It is fixed；Embodiment 2-8 shows：In argentiferous system, change the surface charge of silica, silica concentration, silver ion it is dense The concentration of concentration hydrogen peroxide etc. of degree, sulfate radical can obtain satisfied tungsten removal speed, the silica that greatly improves The rate of decay of stability and polishing velocity.

In conclusion the chemical mechanical polishing liquid of the present invention is shown by changing the charge of abrasive grains silica surface The stability for improving polishing fluid is write, the stability of polishing is further improved, improves polishing efficiency, reduce and be polished to This.

Specific embodiments of the present invention are described in detail above, but it is intended only as example, it is of the invention and unlimited It is formed on particular embodiments described above.To those skilled in the art, it is any to the equivalent modifications that carry out of the present invention and It substitutes also all among scope of the invention.Therefore, the impartial conversion made without departing from the spirit and scope of the invention and Modification, all should be contained within the scope of the invention.

Claims (15)

1. a kind of chemical mechanical polishing liquid, comprising water, the electronegative abrasive grains in surface can generate the compound of silver ion, energy Generate the compound and peroxide of sulfate ion.

2. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the abrasive grains are in 2~4 range of pH value When surface with 30mv to the silica of 70mv negative electrical charges.

3. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the abrasive grains content for 0.1~ 20wt%.

4. the chemical mechanical polishing liquid as described in claim 1 or 3, which is characterized in that the abrasive grains content for 0.5~ 6wt%.

5. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the compound that can generate silver ion is sulphur Sour silver, silver nitrate, silver fluoride and/or silver perchlorate soluble silver salt.

6. the chemical mechanical polishing liquid as described in claim 1 or 5, which is characterized in that the compound that silver ion can be generated Content is 0.001%~0.2wt%.

7. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the compound that sulfate ion can be generated For sulfate.

8. the chemical mechanical polishing liquid as described in claim 1 or 7, which is characterized in that the sulfate is nonmetallic sulfate.

9. chemical mechanical polishing liquid as claimed in claim 8, which is characterized in that the nonmetallic sulfate is ammonium sulfate.

10. the chemical mechanical polishing liquid as described in claim 1 or 7, which is characterized in that the ammonium sulphate content is 0.1% ~0.3wt%.

11. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the peroxide is hydrogen peroxide.

12. the chemical mechanical polishing liquid as described in claim 1 or 11, which is characterized in that the peroxide content for 0.1~ 5wt%.

13. chemical mechanical polishing liquid as claimed in claim 12, which is characterized in that the peroxide content for 1~ 2wt%.

14. chemical mechanical polishing liquid as described in claim 1, which is characterized in that the chemical mechanical polishing liquid also includes PH adjusting agent.

15. the chemical mechanical polishing liquid as described in claim 1 or 14, which is characterized in that the chemical mechanical polishing liquid PH value is 2~4.