CN106928861A - A kind of barrier layer chemical mechanical polishing liquid of alkalescence - Google Patents

Abstract

The present invention provides a kind of alkalescence polishing liquid for barrier polishing, contains:A () abrasive grains (b) azole compounds (c) phosphoric acid (d) ammonium chloride (e) end group has Low K materials inhibitor (f) oxidants (g) water of polyethylene glycol, polypropylene glycol, ethylene glycol and the propylene glycol copolymers of amino.The polishing fluid with the polishing velocity of Selective depression Low K materials, can improve butterfly defect and the local erosion of chip surface by adding the copolymer of polyethylene glycol of the end group containing amino, polypropylene glycol, ethylene glycol and propane diols.

Description

A kind of barrier layer chemical mechanical polishing liquid of alkalescence

Technical field

Barrier layer is applied to the present invention relates to a kind of chemical mechanical polishing liquid and its application, more particularly to one kind Alkalescence polishing liquid.

Background technology

Chemically mechanical polishing (CMP), is the most effectual way for realizing chip surface planarization.

Barrier layer stops that copper ion spreads to dielectric layer generally between silica and copper cash, playing Effect.During polishing, the copper first on barrier layer is removed.Due to now copper polishing velocity quickly, Various defects can be formed (for example：Butterfly defect dishing, and corrode erosion).When copper is polished, Usually require that copper CMP first stops over the barrier layer, then changing another special barrier polishing solution, Removal barrier layer (such as tantalum), while butterfly defect dishing and erosion erosion are modified, Realize global planarizartion.

Tantalum is the conventional metal in barrier layer.In existing polishing technology, there are certain methods to improve resistance The polishing velocity of barrier, such as US7241725, US7300480 imines, hydrazine, guanidine lifting barrier layer Polishing velocity.US7491252B2 lifts the polishing velocity on barrier layer with guanidine hydrochloride.US7790618B2 Imine derivative and polyethylene glycol sulfate surfactant are used, for the polishing on barrier layer.

With continuing to develop for technology, Low-K materials are introduced into manufacture of semiconductor.For containing Low-K In the barrier polishing of material, it is desirable to which the polishing velocity of silica (TEOS) is greater than or equal to Low-K The polishing velocity of material.Polishing velocity " quickly " from the outset is only in this way just can guarantee that, slow drop It is low, reach a rational speed before stopping is polished, it is ensured that between TEOS/BD/ULK/Cu There is a suitable selection ratio, so as to realize global planarizartion (Fig. 1).This is after copper, tantalum, titanium dioxide After silicon materials, the polishing fluid to barrier layer proposes requirement higher in terms of polishing velocity.

At present, commercialized barrier polishing solution has acid and two kinds of alkalescence, respectively there is advantage and disadvantage.It is acid Barrier polishing solution is adjusted to the polishing velocity of copper easily by hydrogen peroxide, and stabilized hydrogen peroxide, but right The polishing velocity of silica and TiN is slower；And alkali barrier polishing fluid is not allowed the polishing velocity of copper Easily adjusted by hydrogen peroxide, and dioxygen water unstable, but to the polishing velocity of silica and TiN compared with Hurry up.

Known alkalescence polishing liquid is applied to the barrier polishing containing Low-K materials generally has one Shortcoming:TEOS polishing velocities can be noticeably greater than the polishing velocity of Low-K materials, because Low-K materials The mechanical strength of material is weaker relative to TEOS.In order to the polishing velocity for suppressing Low-K materials is very fast, Would generally select to add polishing velocity inhibitor, optionally suppress the polishing velocity of Low-K materials. This is a very challenging job, because polishing velocity inhibitor would generally suppress simultaneously The polishing velocity of TEOS and Low-K materials, can so cause silica to throw motionless, polishing velocity Slowly.Although the polishing velocity that more conventional situation is Low-K materials can partly be suppressed, difficult To realize that polishing velocity is less than TEOS.Planarization well can not finally be realized.

In addition, there are patent notes both at home and abroad, Low-K materials are suppressed by adding surfactant Low Jie is suppressed using quaternary cationics in polishing velocity, such as CN101665664A The polishing velocity of electric material (such as BD).Described cation quaternary ammonium salt contains the long-chain of more than C8, But most of quaternary ammonium salt cationic surfactants can significantly inhibit the throwing of silica (OXIDE) Ray velocity, can prevent polishing, and polishing fluid system is very unstable, and this is that reason cationic charge is neutralized The negative electricity on polishing particles surfaces, reduces Coulomb repulsion；And for example, EP2119353A1 is used Poly (methyl vinyl ether) be used for containing Low-K materials polishing, but polyethenoxy ether class it is non-from Sub- surfactant, can be in Low-K material surface strong adsorptions, it is difficult to clean, while causing measurement Error.For another example, US2008/0276543A1 is by carbonamidine, guanidine and polyvinylpyrrolidone (PVP) Mixture be used for barrier layer polishing, but polyvinylpyrrolidone (PVP) to low-K materials throw The inhibition difference of ray velocity is very big, by taking ULK as an example, inhibitions of the PVP to its polishing velocity It is very unobvious.

So need to find more suitably Low-K materials inhibitor, when realizing polishing, polishing velocity from Upper strata is slowed down gradually to lower floor, finally realizes suitable TEOS/BD/ULK/Cu selections ratio, so that Realize global planarizartion.

Except above mentioned problem, either under the conditions of acidity polishing or alkaline polishing, edge mistake is frequently encountered Degree corrodes the problem of (edge-over-erosion, EOE), and its shape is also referred to as " canine tooth " (fang). Generally occur after barrier polishing.At the steel structure edge of bulk, the dielectrics such as silica are had Missing, formed groove.Sometimes also can be appreciated that due to the missing of the copper that galvanic corrosion causes.EOE Phenomenon, reduces the flatness of chip surface, when conductive layer, dielectric layer are in layer superimposed upwards, May proceed to influence the flatness of last layer, after causing polishing, at each layer of surface indentation, might have The residual of copper, causes the stability of electric leakage, short circuit, thus influence semiconductor.

The content of the invention

It is applied to contain Low-K the invention provides a kind of alkaline chemical mechanical polishing liquid, especially one kind The barrier layer alkalescence polishing liquid of material.Described alkaline polishing liquid energy is suppressing the polishing of Low-K materials While speed, the polishing speed of TEOS higher is kept, generation during medal polish can be improved Butterfly defect and lack erosion, finally realize global planarizartion.

A kind of alkaline chemical mechanical polishing liquid disclosed in the present invention, it includes abrasive grains, azole compounds, Phosphoric acid, ammonium chloride, Low-K material inhibitor, oxidant and water.

Wherein, the abrasive grains are preferably silica, and its content is 5-20wt%.

Wherein, the azole compounds are preferably BTA (BTA), triazole (TAZ), first Base BTA (TTA), its content is 0.02-0.3wt%.

Wherein, the mass percent of the phosphoric acid is 0.05-0.4%.

Wherein, the mass percent of the ammonium chloride is 0-0.03%.

Wherein, polyethylene glycol of the end group containing amino, polypropylene glycol, ethylene glycol and propylene glycol copolymers Low-K material inhibitor.Its structural formula is any one following：

Structure 1

Structure 2

Structure 3

Herein, R is hydrogen or methyl, the active hydrogen equivalent weight (amine of the Low-K materials inhibitor Hydrogen equivalent weight, write a Chinese character in simplified form AHEV values) it is 80-1100, its content is 0.01-0.2%.

Wherein, described hydrogen peroxide mass percent is 0.1-2%.

Wherein, the pH value of described polishing fluid is 9-11.

Wherein, also including this area such as water and pH adjusting agent common additives in described alkalescence polishing liquid.

The technical effects of the invention are that：

1) polishing fluid of the invention can suppress Low-K materials by adding Low-K materials inhibitor Polishing velocity, realizes the polishing of the polishing velocity more than or equal to Low-K materials of silica (TEOS) Speed, it has a good application prospect in terms of barrier polishing.

2) polishing fluid of the invention can be effectively improved the butterfly defect that shows of polishing rear substrate and to lack erosion existing As so as to realize the global planarizartion of base material.

Brief description of the drawings

Fig. 1 is the silicon chip sectional drawing that polishing fluid is used for barrier polishing

Specific embodiment

Alkalescence polishing liquid of the invention can be prepared as follows：Other components in addition to oxidant are pressed Ratio is well mixed, and is adjusted to required pH value with pH adjusting agent (such as KOH or HNO3), Using preceding oxidizer, it is well mixed.Wherein, water is surplus.

Agents useful for same of the present invention and raw material are commercially available.

The advantage of invention is expanded on further below by specific embodiment, but protection scope of the present invention is not only It is limited only to following embodiments.

According to each embodiment in table 1 and the composition and its proportions polishing fluid of comparative example.Table 1 It is mass percent with the concentration in table 2.Wherein polishing condition is：Mirra polishing machine platforms, Fujibo Polishing pad, polish pressure 1.5PSI polishes flow quantity 140mL/min, polishing disk/rubbing head rotating speed： 103/97RPM。

The component and content of polishing fluid in the embodiment of table 1 (Examples)

The component and content of polishing fluid in the comparative example of table 2

As shown in table 3, comparative example 1,2 show, are not added with Low-K material inhibitor, the throwing of Low-K Ray velocity can cause very deep butterfly defect and lack erosion quickly, and comparative example 3,4 shows, adds Low-K After material inhibitor, the polishing velocity of Low-K can be suppressed to less than TEOS (silica), Scarce erosion has a certain degree of improvement, but still can not reach technological requirement.Embodiment 1-6 shows, Use formula of the invention, it is possible to achieve throwing of the polishing velocity of Low-K less than TEOS (silica) Ray velocity, while significantly improving butterfly defect and lacking erosion.

The polishing situation of the embodiment of table 3 and comparative example

Specific embodiment of the invention has been described in detail above, but it is intended only as example, this hair It is bright to be not restricted to particular embodiments described above.To those skilled in the art, it is any to this The equivalent modifications that carry out of invention and substitute also all among scope of the invention.Therefore, this hair is not being departed from The impartial conversion and modification made under bright spirit and scope, all should be contained within the scope of the invention.

Claims (13)

1. a kind of barrier polishing solution of alkalescence, contains abrasive grains, azole compounds, phosphoric acid, ammonium chloride, oxidant, water and Low-K material inhibitor, it is characterised in that the Low-K materials inhibitor is the copolymer of polyethylene glycol of the end group containing amino, polypropylene glycol, ethylene glycol and propane diols.

2. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that copolymer structure of the end group containing the polyethylene glycol of amino, polypropylene glycol, ethylene glycol and propane diols is any one following：

R is hydrogen or methyl.

3. the barrier polishing solution of alkalescence as claimed in claim 2, it is characterised in that the active hydrogen equivalent weight of the copolymer of polyethylene glycol of the end group containing amino, polypropylene glycol, ethylene glycol and propane diols is 80-1100.

4. the barrier polishing solution of alkalescence as claimed in claim 2, it is characterised in that the mass percentage content of polyethylene glycol of the end group containing amino, polypropylene glycol, ethylene glycol and propylene glycol copolymers is 0.01-0.2%.

5. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the abrasive grains are silica.

6. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the mass percentage content of the abrasive grains is 5-20%.

7. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the azole compounds are BTA (BTA), triazole (TAZ), methyl benzotriazazole (TTA).

8. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the azole compounds mass percentage content is 0.02-0.3%

9. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the mass percentage content of the phosphoric acid is 0.05-0.4%.

10. the barrier polishing solution of alkalescence as claimed in claim 1, it is characterised in that the mass percentage content of the ammonium chloride is 0-0.03%.

The barrier polishing solution of 11. alkalescence as claimed in claim 1, it is characterised in that the oxidant is hydrogen peroxide.

The barrier polishing solution of 12. alkalescence as claimed in claim 1, it is characterised in that the mass percentage content of the oxidant is 0.1-2%.

The barrier polishing solution of 13. alkalescence as claimed in claim 1, it is characterised in that the pH value of the polishing fluid is 9-11.