CN102816528A - Chemical-mechanical polishing solution for polishing tungsten - Google Patents
Chemical-mechanical polishing solution for polishing tungsten Download PDFInfo
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- CN102816528A CN102816528A CN 201110152797 CN201110152797A CN102816528A CN 102816528 A CN102816528 A CN 102816528A CN 201110152797 CN201110152797 CN 201110152797 CN 201110152797 A CN201110152797 A CN 201110152797A CN 102816528 A CN102816528 A CN 102816528A
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Abstract
The invention discloses a chemical-mechanical polishing solution for polishing tungsten. The polishing solution comprises an abrasive material formed by a mixture of silicon sol and fumed silica, silver ions, sulfate ions and a hyperoxide. The polishing solution has very high tungsten-polishing rate, simultaneously has adjustable selection ratio of tungsten/silica, and can reduce surface defects of chips significantly.
Description
Technical field
The present invention relates to a kind of chemical mechanical polishing liquid, relate in particular to a kind of chemical mechanical polishing liquid with high speed tungsten polishing speed.
Background technology
Along with the continuous development of semiconductor technology, and the continuous increase of large-scale integrated circuit interconnection layer, it is particularly crucial that the planarization of conductive layer and insulating medium layer becomes.Twentieth century eighties, be considered to the effective means of present overall planarization by chemically machinery polished (CMP) technology of IBM Corporation's initiative.Main mechanism to metal level chemically machinery polished (CMP) is considered to: oxygenant is earlier with the oxidation on metal surface film forming; The abrasive that with silicon-dioxide and aluminum oxide is representative is removed this layer sull machinery; Producing new metallic surface continues oxidized; These two kinds collaborative the carrying out of effect, i.e. chemically machinery polished (CMP) is by chemical action, mechanical effect and these two kinds effect be combined intos.
CMP is usually by a grinding stage that has polishing pad, and a grinding head that is used for carries chips is formed.Wherein grinding head is fixed chip, and the front with chip is pressed on the polishing pad then.When carrying out chemically machinery polished, grinding head linearity on polishing pad moves or rotates along the heading the same with grinding stage.Meanwhile, the slurries that contain abrasive are dripped on the polishing pad, and are tiled on the polishing pad because of centrifugation.Chip surface is realized overall planarization under machinery and chemical dual effect.
The metal interconnection of IC interior structure realizes through multilayer is interconnected, has insulation layer between every layer of metal level, normally silicon-dioxide.The binding of the metal between the different layers realizes that through via (path) these via (path) are made up of tungsten (tungsten via) usually.Between tungsten and insulation layer, have adhesive linkage (adhesion layer) usually, bonding layer material commonly used is TiN or Ti.In the actual course of processing,, in interlayer insulating film (ILD), form via (path) with the way of etch (etching); Arriving at needs banded lead or device; Form very thin adhesive linkage (adhesion layer) on the surface of insulation layer (ILD) and via (path) then, then, fill tungsten (tungsten) among the via (path); At last, the unnecessary tungsten in upper strata is removed with the method for chemically machinery polished.Form tungsten plug (tungsten plugs) by this method.
Chemically machinery polished (CMP) for tungsten has several different methods:
1991; F.B.Kaufman etc. have reported that the Tripotassium iron hexacyanide is used for the method for tungsten chemically machinery polished (" Chemical Mechanical Polishing for Fabricating Patterned W MetalFeatures as Chip Interconnects "; Journal of the Electro chemical Society; Vol.138, No.11, in November, 1991); USP 5340370 discloses a kind of prescription that is used for tungsten chemically machinery polished (CMP); Wherein contain the 0.1M Tripotassium iron hexacyanide, because the Tripotassium iron hexacyanide is under UV-light or sun exposure, and in acidic medium; Can decomposite the prussic acid of severe toxicity, thereby limit it and be widely used.
USP 5527423, USP 6008119, USP 6284151 grades disclose the (NO with Fe
3)
3, alumina system is used for the method for tungsten mechanical polishing (CMP).This polishing body ties up to product defects (defect) aspect and exists significantly not enough.The iron nitrate of high density makes the pH value of polishing fluid be strongly-acid, severe corrosion equipment simultaneously.In addition, the conduct of the iron ion of high density is metals ion movably, has seriously reduced the safety of semiconductor components and devices.
USP 5958288 discloses iron nitrate has been used as catalyzer, and hydrogen peroxide is used as oxygenant, carries out the method for tungsten chemically machinery polished.Because the existence of iron ion, and the Fenton reaction takes place between the ydrogen peroxide 50, ydrogen peroxide 50 can be rapidly and decomposition failure tempestuously, so there is the problem of poor stability in this polishing fluid.
USP 5980775 and USP 6068787 are on USP 5958288 bases; Add organic acid and make stablizer; Improved the rate of decomposition of hydrogen peroxide, but hydrogen peroxide decomposition speed is still higher, hydrogen peroxide concentration can reduce more than 10% in common two weeks; Cause polishing velocity to descend, polishing fluid is decomposition failure gradually.
Chinese patent 98809580.7 and 200610077360.7 has added the erosion inhibitor of tungsten in ydrogen peroxide 50 adds the system of iron, suppress the corrosion of tungsten.
But in polishing process, have requirement, be referred to as to select ratio to metal level with to the ratio of the polishing velocity of insulation layer.When selecting ratio too low (insulation layer polishing velocity and metal level polishing velocity are all very fast), insulation layer has lost barrier effect, can cause the thickness of polishing chip defective.(the insulation layer polishing velocity is slow when selecting ratio too high; Medal polish speed is fast), when crossing throwing (over-polish), insulation layer is thrown motionless; And the continuous polished liquefaction corrosion of the metal that touches polishing fluid; Like this, at metal area, form butterfly defective (dishing) and metal depression (recess) easily.
In the CMP process, another kind of undesirable phenomenon is to corrode (erosion), and corroding (erosion) is surface of insulating layer and intensive metallic region (vias or trenches) the rugged phenomenon of surface elevation.The polishing velocity of intensive metallic region (vias or trenches) usually can be faster than insulation layer on every side, and serious erosion (erosion) is unacceptable in the chip manufacture process.
Along with semiconductor technology constantly develops to smaller szie; To the planarization of the chip surface overall situation require increasingly high; Especially after 45 nanometers or littler technology node; Polishing fluid must possess the selection ratio of moderate insulator/metal layer when possessing higher polishing velocity, guarantee polishing thickness, low (erosion), low butterfly defective (dishing) and the low metal depression (recess) of corroding.
Summary of the invention
The invention provides a kind of chemical mechanical polishing liquid that can high speed polishing tungsten; Combination through silver ions and sulfate ion; And the mixed-abrasive of employing silicon sol and fumed silica, well solved the problem of regulating the tungsten/silicon dioxide polishing selection ratio.
The chemical mechanical polishing liquid of polish tungsten of the present invention, component mainly comprises: the material (following but also claim sulfate ion) that can ionization in abrasive, oxygenant, the material (not only following claim silver ions) that can ionization in polishing fluid goes out silver ions, the polishing fluid goes out sulfate ion.
In the present invention, said abrasive is preferably silicon sol and fumed silica mixed-abrasive; Silicon sol and fumed silica mass ratio are preferably 0.1～1.5 in the said abrasive: 0.1～3; More preferably, said silicon sol mass percent in polishing fluid is 0.1～1.5%, most preferably is 0.5～1%; Said fumed silica mass percent in polishing fluid is 0.1～3%, most preferably is 1～2%.
In the present invention; The said material that can ionization goes out silver ions can be a kind of or any several kinds compsn in Sulfuric acid disilver salt, Silver Nitrate, tachyol and the silver perchlorate soluble silver salt; Preferably, said silver salt mass percent in polishing fluid is 0.05%～0.3%.
In the present invention, the material that can ionization goes out sulfate ion is a vitriol, like sodium sulfate, vitriolate of tartar; Preferably, said vitriol is nonmetal vitriol, more preferably ammonium sulfate.
In the present invention, said oxygenant is a superoxide, is preferably hydrogen peroxide, and its mass percent in polishing fluid is preferably 0.5～5%.
As required, polishing fluid of the present invention can also comprise pH value regulator; Said polishing fluid pH value is preferably 0.5～5.
Polishing fluid of the present invention has higher tungsten polishing speed, and has good tungsten and silicon-dioxide removal selectivity, and polishing fluid system stability simultaneously of the present invention is better.
Embodiment
Through specific embodiment polishing fluid of the present invention is described in detail below and explain that so that better understand the present invention, still, following embodiment does not limit protection domain of the present invention.
Table 1 has provided polishing fluid of the present invention and contrast polishing fluid main ingredient and content thereof, by listed component and content thereof in the table, in deionized water, mixes, and is transferred to required pH value with pH regulator agent (nitric acid or Pottasium Hydroxide), can make chemical mechanical polishing liquid.
Polishing condition: 8 inches industrial polishing machine platforms (Mirra), polish pressure: 3.8psi, polishing fluid flow: 100mL/min.
Table 1, polishing fluid embodiment 1～7 of the present invention and Comparative Examples 1～6 main ingredient and quality percentage composition thereof
Table 2, the defective of using fumed silica and silicon sol abrasive to bring separately
Through the experiment contrast, as shown in table 2, from regulating suitable selection,, no matter heighten or turn down the concentration of abrasive if adopt single abrasive than angle, all can produce corresponding problem.For example single employing silicon sol (colloidal silica) is made abrasive; Itself inherent characteristic is: the polishing velocity to insulation layer silicon-dioxide is very fast; If reduce the insulation layer polishing velocity; Naturally can take into account the reduction abrasive concentration, alleviate mechanical force, but can produce pronounced side effects like this: cause serious silicon slice surface defects rising (reason is still among research).If single employing fumed silica (fumedsilica) is made abrasive, itself inherent characteristic is: the polishing velocity to insulation layer silicon-dioxide is very low, if improve this speed; Will consider the rising abrasive concentration, increase mechanical force, but increase the concentration of fumed silica (fumed silica); The ability of rising polishing velocity is very limited; Increase cost simultaneously, caused the polishing fluid system very unstable, formed deposition.
Table 3, the concrete polishing effect contrast of the embodiment of the invention and Comparative Examples polishing fluid
Table 3 has provided polishing fluid of the present invention and the concrete polish results of Comparative Examples polishing fluid, wherein:
Comparative Examples 1,2,3 adopts single silicon sol to make abrasive, can find out that silicon sol is very fast to the polishing velocity of insulation layer silicon-dioxide, Comparative Examples 1; Though silicon slice surface defects is qualified, the polishing velocity of silicon-dioxide is too fast, and tungsten/silicon dioxide is selected lower than too; Can not satisfy processing requirement, need to reduce the polishing velocity (regulating the selection ratio of tungsten/silicon dioxide) of silicon-dioxide, for this reason; Reduced the concentration of silicon sol in the Comparative Examples 2,3, reduced the polishing velocity of silicon-dioxide, but discovery can cause silicon slice surface defects to raise rapidly; Therefore use the system of silicon sol, the selection of tungsten/silicon dioxide is more on the low side than generally (being lower than 10).
Comparative Examples 4,5,6 adopts single aerosil to make abrasive; Can find out that aerosil is very slow to the polishing velocity of insulation layer silicon-dioxide; In order to regulate the selection ratio of tungsten/silicon dioxide, in Comparative Examples 6, increased the concentration of aerosil, find the stability decreases of polishing fluid system; Therefore use the system of aerosil, the selection ratio of tungsten/silicon dioxide is very high (greater than 50) generally.
Embodiment 1～7 adopts silicon sol and fumed silica to mix, and as abrasive, according to two kinds of ratios that abrasive is different, can regulate tungsten/silicon dioxide and select ratio, the more important thing is that the defective of silicon chip surface is qualified, and the system of polishing fluid is stable simultaneously.Can realize the technique effect that single silicon sol or single aerosil can't be realized.
More than specific embodiment of the present invention is described in detail, but it is just as example, the present invention is not restricted to the specific embodiment of above description.To those skilled in the art, any equivalent modifications that the present invention is carried out with substitute also all among category of the present invention.Therefore, not breaking away from impartial conversion and the modification of being done under the spirit and scope of the present invention, all should contain within the scope of the invention.
Claims (15)
1. the chemical mechanical polishing liquid of a polish tungsten; It is characterized in that: said polishing fluid comprises abrasive, oxygenant, can ionization in polishing fluid go out in material and the polishing fluid of silver ions the material that can ionization goes out sulfate ion; Wherein, said abrasive is silicon sol and fumed silica mixed-abrasive.
2. chemical mechanical polishing liquid as claimed in claim 1 is characterized in that: silicon sol and fumed silica mass ratio are 0.1～1.5: 0.1～3 in the said abrasive.
3. according to claim 1 or claim 2 chemical mechanical polishing liquid, it is characterized in that: said fumed silica mass percent is 0.1～3%.
4. chemical mechanical polishing liquid as claimed in claim 3 is characterized in that: said fumed silica mass percent is 1～2%.
5. according to claim 1 or claim 2 chemical mechanical polishing liquid, it is characterized in that: said silicon sol mass percent is 0.1～1.5%.
6. chemical mechanical polishing liquid as claimed in claim 5 is characterized in that: said silicon sol mass percent is 0.5～1%.
7. chemical mechanical polishing liquid as claimed in claim 1 is characterized in that: the said material that can ionization goes out silver ions is one or more in Sulfuric acid disilver salt, Silver Nitrate, tachyol and the silver perchlorate soluble silver salt.
8. like claim 1 or 7 described chemical mechanical polishing liquids, it is characterized in that: the said material mass per-cent that can ionization goes out silver ions is 0.05～0.3%.
9. chemical mechanical polishing liquid as claimed in claim 1 is characterized in that: the said material that can ionization goes out sulfate ion is a vitriol.
10. chemical mechanical polishing liquid as claimed in claim 9 is characterized in that: said vitriol is nonmetal vitriol.
11. chemical mechanical polishing liquid as claimed in claim 10 is characterized in that: said nonmetal vitriol is ammonium sulfate.
12. chemical mechanical polishing liquid as claimed in claim 1 is characterized in that: said oxygenant is a hydrogen peroxide.
13. like claim 1 or 12 described chemical mechanical polishing liquids, it is characterized in that: said oxygenant mass percent is 0.5～5%.
14. chemical mechanical polishing liquid as claimed in claim 1 is characterized in that: also comprise pH value regulator.
15. chemical mechanical polishing liquid as claimed in claim 14 is characterized in that: said polishing fluid pH value is 0.5～5.
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| CN 201110152797 CN102816528A (en) | 2011-06-08 | 2011-06-08 | Chemical-mechanical polishing solution for polishing tungsten |
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| CN 201110152797 CN102816528A (en) | 2011-06-08 | 2011-06-08 | Chemical-mechanical polishing solution for polishing tungsten |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111378373A (en) * | 2018-12-28 | 2020-07-07 | 安集微电子（上海）有限公司 | Chemical mechanical polishing solution for polishing tungsten |
| CN111378374A (en) * | 2018-12-28 | 2020-07-07 | 安集微电子科技（上海）股份有限公司 | Chemical mechanical polishing solution |
-
2011
- 2011-06-08 CN CN 201110152797 patent/CN102816528A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111378373A (en) * | 2018-12-28 | 2020-07-07 | 安集微电子（上海）有限公司 | Chemical mechanical polishing solution for polishing tungsten |
| CN111378374A (en) * | 2018-12-28 | 2020-07-07 | 安集微电子科技（上海）股份有限公司 | Chemical mechanical polishing solution |
| CN111378374B (en) * | 2018-12-28 | 2022-05-13 | 安集微电子科技（上海）股份有限公司 | Chemical mechanical polishing solution |
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Application publication date: 20121212 |