WO2010025623A1

WO2010025623A1 - A chemical-mechanical polishing liquid

Info

Publication number: WO2010025623A1
Application number: PCT/CN2009/001000
Authority: WO
Inventors: 宋伟红; 姚颖
Original assignee: 安集微电子科技(上海)有限公司
Priority date: 2008-09-05
Filing date: 2009-09-04
Publication date: 2010-03-11
Also published as: CN102137904A; CN101665662A; CN102137904B

Abstract

The present invention discloses a chemical-mechanical polishing liquid comprising colloidal silicon dioxide particles, organic carboxylic acid and/or organic phosphonic acid, potassium nitrate and water. To satisfy the demand of a chemical-mechanical polishing liquid for polishing oxide dielectric materials, the present invention provides a chemical-mechanical polishing liquid having high removal rate of oxide dielectric materials.

Description

Chemical mechanical polishing liquid

The present invention relates to a chemical mechanical polishing liquid. technical background

In the fabrication of integrated circuits, thousands of structural cells are often built on silicon wafer substrates, which further form functional circuits and components through multilayer metal interconnects. In a multi-layer metal interconnect structure, silicon dioxide or silicon dioxide doped with other elements is interposed between the metal wires as an interlayer dielectric (ILD). With the development of integrated circuit metal interconnect technology and the increase in the number of wiring layers, chemical mechanical polishing (CMP) has been widely used for surface planarization in chip manufacturing processes. These planarized chip surfaces facilitate the production of multilayer integrated circuits and prevent distortion caused by coating the dielectric layer on uneven surfaces.

The CMP process uses an abrasive-containing mixture and a polishing pad to polish the surface of the integrated circuit. In a typical chemical mechanical polishing process, the substrate is placed in direct contact with a rotating polishing pad and a load is applied to the back side of the substrate with a load. During polishing, the gasket and the table rotate while maintaining a downward force on the back of the substrate, applying abrasive and chemically active solutions (often referred to as polishing fluids or polishing slurries) to the gasket. The polished film undergoes a chemical reaction to begin the polishing process.

In the oxide polishing process, the polishing slurry is mainly used to remove the oxide dielectric. When polishing shallow trench isolation layers, the polishing fluid is primarily used to remove and planarize oxide dielectrics and silicon nitride. Higher oxide dielectric removal rates and lower surface defects are required in both oxide and shallow trench isolation polishing processes. When polishing an oxide dielectric, it is always desirable to have a higher silica removal rate while other materials have a lower polishing rate. The oxide dielectric includes thin thermal oxide, high density plasma oxide, borophosphosilicate glass, tetraethoxy silica (PETEOS) and miserable Carbon doped oxide, etc.

Polishing abrasives for oxide dielectric polishing slurries are primarily fumed silica, ceria and sol silica, but the first two abrasives tend to scratch the surface during polishing. Compared with the first two kinds of abrasives, the sol-type silica produces less surface defects during polishing, but the removal rate of the oxide dielectric is lower, and the amount of abrasive in the polishing liquid tends to be higher, pH value. Also higher.

U.S. Patent No. 5,891,205, the disclosure of which is incorporated herein incorporated by incorporated herein its entirety A colloidal silica polishing solution having a high selectivity of silica and silicon nitride, comprising 5 to 50% of silica colloidal particles and 0.001 to 2.0 of a sulfonate or sulfonate, is disclosed in US Pat. No. 6,964,600. Composition. Patent US 7,351,662 uses a bicarbonate to promote the removal rate of an oxide dielectric (silica or carbon-doped silica) to achieve lower surface defects. Summary of invention

The technical problem to be solved by the present invention is to provide a chemical mechanical polishing liquid having a high rate of removal of an oxide dielectric in order to meet the requirements of a chemical mechanical polishing liquid for polishing an oxide dielectric.

The chemical mechanical polishing liquid of the present invention contains silica sol particles, an organic carboxylic acid and/or an organic phosphonic acid compound, potassium nitrate and water.

The carboxylic acid according to the present invention is a compound having a carboxyl group in the molecule, preferably one or more of a binary and tribasic carboxylic acid having 2 to 6 carbon atoms, more preferably oxalic acid, tartaric acid, or sub One or more of aminodiacetic acid, ammonia triacetic acid, and citric acid.

'The organic phosphonic acid compound of the present invention is a compound containing a phosphonic acid group in the molecule (e.g., Formula 1) Compound

Formula 1

Preferably, it is one or more of a phosphonic acid compound having 1 to 4 phosphonic acid groups represented by Formula 1 and having 2 to 20 carbon atoms (more preferably 2 to 16). More preferred are hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylene phosphonic acid (ATMP), 2-hydroxyphosphonoacetic acid (HPAA), 2-phosphonium bromide-1, 2, 4-tricarboxylate One or more of acid (PBTCA) and polyaminopolyethermethylene phosphonic acid (PAPEMP).

The content of the organic carboxylic acid and/or the organic phosphonic acid compound is preferably from 0.2 to 3%, more preferably from 0.2% to 1%, most preferably from 0.2 to 0.5%; and the percentage is percentage by mass.

The content of potassium nitrate is preferably from 0.2 to 3%, more preferably from 0.2% to 1%, most preferably from 0.2 to 0.5%; and the percentage is percentage by mass.

The silica colloidal particles preferably have a particle diameter of 50 to 100 nm. The content of the silica colloidal particles is preferably from 15 to 38%; more preferably from 15 to 25%; and the percentage is percentage by mass.

A preferred embodiment of the invention further comprises a surfactant, preferably a nonionic and/or amphoteric surfactant, more preferably lauroyl propyl amine oxide, dodecyl dimethyl oxide Amine (OA-12), cocamidopropyl betaine (CAB-30), Tween 20, taudecyl dimethyl betaine (BS-12), cocamidopropyl beet One or more of a base (CAB-35) and a coconut fatty acid diethanolamide (6501). The surfactant is preferably used in an amount of 0.2% or less, excluding 0%, more preferably 0.005 to 0.05%; and the percentage is percentage by mass.

When a nonionic or amphoteric surfactant is used, by adjusting the kind of the surfactant, different polysilicon removal rates can be obtained, thereby achieving the purpose of adjusting the polysilicon removal rate. For example, dodecyl dimethyl betaine has a high removal rate of polysilicon, while cocamidopropyl betaine The polysilicon removal rate is low, and with both surfactants, the resulting polysilicon removal rate is between the removal rates when used alone.

Preferably, the water is deionized water, and the water is supplemented to 100%; the percentage is the mass percentage.

Depending on the actual needs of the process, auxiliary agents conventionally added in the art, such as viscosity modifiers, alcohol or ether reagents, bactericides and the like, may be added to the polishing liquid of the present invention.

The pH of the polishing liquid of the present invention is preferably from 9 to 12, most preferably from 9.5 to 10.5.

The polishing liquid of the present invention can be obtained by simply and uniformly mixing the above components, followed by adjustment to a suitable pH with a pH adjuster. The pH adjusting agent may be selected from conventional pH adjusting agents in the art, such as potassium hydroxide and aqueous ammonia.

The reagents used in the present invention are all commercially available.

A positive progressive effect of the present invention is that the polishing fluid of the present invention has a higher polishing rate for the oxide dielectric. In a preferred embodiment of the invention, a higher removal rate can be achieved with a lower silica content in the polishing fluid, and the cost of the polishing fluid is lower. DRAWINGS

Figure 1 is a graph of TEOS removal rates for organic carboxylic acids, potassium nitrate, and combinations thereof.

Figure 2 is a graph showing the TEOS removal rate for different types of organic carboxylic acids and/or organic phosphonic acids.

Figure 3 is a graph showing the TEOS removal rate for various amounts of organic carboxylic acids and/or organic phosphonic acids and potassium nitrate.

Figure 4 is a graph of TEOS removal rates for polishing solutions of different pH values. Figure 5 is a graph of TEOS removal rates for different amounts of silica abrasive.

Figure 6 is a graph showing the removal rates of TEOS, Si ₃ N ₄ and Poly for different surfactants.

Summary of the invention

The invention is further illustrated by the following examples, but the invention is not limited thereto.

Quaternary ammonium salt cationic surfactant 31425 Henan Road Purification Co., Ltd.

The percentages in each of the following examples are percentages by mass.

Example 1 Promotion of organic carboxylic acid and potassium nitrate

Table 1

The silica (TEOS) removal rate was measured by polishing the silica with the comparative polishing liquids 1 to 3 and the polishing liquid 1, as shown in Fig. 1. As can be seen from the figure, both organic carboxylic acid and potassium nitrate can increase the polishing rate of the abrasives, respectively, and their combination can achieve a higher polishing rate. The formulation of the polishing solution is shown in Table 1. The components are simply and uniformly mixed according to the contents listed in Table 1. The deionized water is made up to 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: 5.0 psi under pressure, polishing pad IC1000, polishing plate speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5 o

Example 2 Effect of Kinds of Organic Carboxylic Acid and/or Organic Phosphonic Acid Compound on TEOS Removal Rate Silicon dioxide was polished with a polishing liquid of 2 to 10 to measure the removal rate of silica, as shown in Fig. 2. By It can be seen that the polishing liquid of the present invention can achieve a very high silica removal rate.

The formulation of the polishing solution is shown in Table 2. The components are simply and uniformly mixed according to the contents listed in Table 2. The deionized water is used to make up 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: downforce 5.0 psi, polishing pad IC1000, polishing disk speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5.

Table 2

Example 3 Effect of the amount of organic carboxylic acid and / or organic phosphonic acid compound, potassium nitrate on the removal rate of TEOS

The silica removal rate was measured by polishing the liquid 11 to 16 and the comparative polishing liquid 4, as shown in Fig. 3. It can be seen from the figure that the effect of organic carboxylic acid and/or organic phosphonic acid compound and potassium nitrate on the removal rate increases with the increase of the amount, reaches saturation after 0.2%, and the removal rate is basically unchanged.

The formulation of the polishing solution is shown in Table 3. The components are simply and uniformly mixed according to the contents listed in Table 3. The deionized water is made up to 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: lower pressure 4.0 psi, throw Light pad IC1000, polishing disk speed 70rpm, polishing fluid flow rate 100ml/min, polishing machine Logitec

table 3

Example 4 Effect of pH of polishing solution on polishing rate

The silica was polished with a polishing liquid 17 to 22, and the removal rate of the silica was measured as shown in Fig. 4. As can be seen from the figure, a high pH value is advantageous for obtaining a high polishing rate, but it does not change much after pH = 10.0, and a preferred pH range is 9.5 to 10.5. The formulation of the polishing solution is shown in Table 4. The components are simply and uniformly mixed according to the contents listed in Table 4. The deionized water is used to make up 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: downforce 4.0 psi, polishing pad IC 1000, polishing disk speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5 o

Table 4

Polished silica organic carboxylic acid and / or organic phosphonic acid compound

pH removal rate Liquid dosage (%) Particle size (nm) Type Dosage (%) Potassium (%) (A/min)

17 19 70 PBTCA 0.5 0.5 9.0 1445

18 19 70 PBTCA 0.5 0.5 9.5 1744

19 19 70 PBTCA 0.5 0.5 10 2036

20 19 70 PBTCA 0.5 0.5 10.5 1918

21 19 ' 70 PBTCA 0.5 0.5 11 1892

22 19 70 PBTCA 0.5 0.5 12 1879 Example 5 Effect of the amount of silica abrasive on the removal rate of TEOS

The silica was polished with a polishing solution 23 to 28, and the removal rate of silica was measured as shown in Fig. 5. As can be seen from the figure, the higher the amount of silica abrasive particles, the greater the removal rate, and the preferred amount is 15-38%.

The formulation of the polishing solution is shown in Table 5. The components are simply and uniformly mixed according to the contents listed in Table 5. The deionized water is used to make up 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: downforce 4.0 psi, polishing pad IC1000, polishing disk speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5 o

Example 6 Surfactant for TEOS, 81 ₃ ^ and ? 0 Effect of removal rate

The removal rates of silicon dioxide, Si ₃ N ₄ and polycrystalline silicon were measured by polishing silica, Si ₃ N ₄ and polycrystalline silicon (Poly) with polishing liquids 29 to 37, as shown in Fig. 6 and Table 7. As can be seen from the figure, the polishing solution containing different surfactants has a marked change in the removal rate of polysilicon. The rate of removal of polycrystalline silicon by dodecyl dimethyl betaine is high, while the rate of polysilicon removal by cocamidopropyl betaine is low. It can be seen that by selecting different surfactants, different removal rates of polysilicon can be achieved, thereby artificially controlling the polysilicon removal rate.

The formulation of the polishing solution is shown in Table 6. The components are simply and uniformly mixed according to the contents listed in Table 6. The deionized water is made up to 100% by mass, and the pH is adjusted with KOH. Polishing conditions are: downforce 4.0 psi, polishing pad IC1000, polishing disk speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5, Table 6

Table 7

Removal rate, A/min

Polishing fluid

TEOS Si ₃ N ₄ multi-day note

29 1925 800 1368

30 2153 795 2686

31 2294 698 1304

32 2263 765 2809

33 1915 687 1023

34 2176 689 1672

35 1964 621 2750

36 1981 728 3047

37 1673 764 1837

Claims

Rights request

A chemical mechanical polishing liquid comprising silica sol particles, an organic carboxylic acid and/or an organic phosphonic acid compound, potassium nitrate and water.

The chemical mechanical polishing liquid according to claim 1, wherein the organic carboxylic acid is one or more selected from the group consisting of binary and tricarboxylic acids having 2 to 6 carbon atoms.

The chemical mechanical polishing liquid according to claim 2, wherein the organic carboxylic acid is one or more of oxalic acid, tartaric acid, iminodiacetic acid, ammonia triacetic acid, and citric acid.

4. The chemical mechanical polishing liquid according to claim 1, wherein the organic phosphonic acid compound is a phosphonic acid compound having 1 to 4 phosphonic acid groups and having 2 to 20 carbon atoms. .

The chemical mechanical polishing liquid according to claim 4, wherein the organic phosphonic acid compound is hydroxyethylidene diphosphonic acid, aminotrimethylenephosphonic acid, 2-hydroxyphosphonoacetic acid, 2 One or more of phosphonium phosphonium-1,2,4-tricarboxylic acid and polyaminopolyethermethylene phosphonic acid.

The chemical mechanical polishing liquid according to claim 1, wherein the content of the organic carboxylic acid and/or the organic phosphonic acid compound is 0.2 to 3% by mass.

The chemical mechanical polishing liquid according to claim 6, wherein the content of the organic carboxylic acid and/or the organic phosphonic acid compound is 0.2% by weight to 1% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the potassium nitrate is contained in an amount of 0.2 to 3% by mass.

The chemical mechanical polishing liquid according to claim 8, wherein the potassium nitrate is contained in an amount of 0.2% by mass to 1% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the silica sol particles have a particle diameter of 50 to 100 nm.

1 1. The chemical mechanical polishing liquid according to claim 1, wherein the content of the silica sol particles is 15 to 38% by mass.

12. The chemical mechanical polishing liquid according to claim 1, wherein the content of the silica sol particles is 15 to 25% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the chemical mechanical polishing liquid further contains a nonionic and/or amphoteric surfactant.

14. The chemical mechanical polishing liquid according to claim 13, wherein: the surfactant is lauroyl propyl amine oxide, dodecyl dimethyl amine oxide, cocamidopropyl betaine. One or more of Tween 20, dodecyldimethylbetaine, cocamidopropyl betaine, and coconut fatty acid diethanolamide.

The chemical mechanical polishing liquid according to claim 13, wherein the surfactant is contained in an amount of 0.2% or less, excluding 0%; and the percentage is a mass percentage.

The chemical mechanical polishing liquid according to any one of claims 1 to 15, wherein the chemical mechanical polishing liquid has a pH of 9 to 12.

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