TWI431081B - Chemical mechanical polishing solution - Google Patents

Description

Chemical mechanical polishing fluid

The present invention relates to a chemical mechanical polishing liquid, and more particularly to a chemical mechanical polishing liquid for polishing polycrystalline germanium.

In the fabrication of integrated circuits, the standard of interconnect technology is increasing, and a layer is deposited on top of one layer, resulting in an irregular topography on the surface of the substrate. One method of planarization used in the prior art is chemical mechanical polishing (CMP), which uses an abrasive-containing mixture and a polishing pad to polish a ruthenium surface. 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 backside 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 polishing process of polycrystalline germanium, there are usually two problems as follows: 1. Because the polishing rate selection ratio of polycrystalline germanium/cerium oxide is too high, so that the final polishing process stops on the germanium dioxide layer, it is inevitable that there will be a polycrystalline germanium dish. Shaped concave. As shown in Fig. 1, a and b in the figure are the structures before and after polishing, respectively. And the problem is aggravated as the width of the trench between the cerium oxide increases. This can have a serious impact on the performance of the device. 2. In the shallow mechanical channel (STI) chemical mechanical polishing process, the surface of the cerium oxide is formed into a dish-shaped concave defect, which causes the polycrystalline germanium to remain in the smear-shaped concave defect during the polishing process after the subsequent step covers the polycrystalline germanium layer. As shown in Fig. 2, a and b in the figure are the structures before and after polishing, respectively. This also has a serious impact on the performance of the device.

Therefore, it is important to solve the problem of surface dishing defects in the polishing process of the polycrystalline silicon and the removal of the trapezoidal disk shape of the polycrystalline germanium.

US 2003/0153189 A1 discloses a chemical mechanical polishing liquid and method for polycrystalline germanium polishing, the polishing liquid comprising a polymer surfactant and an abrasive particle selected from the group consisting of alumina and cerium oxide, the polymer surfactant being a polycarboxylate An acid ester surfactant with which the polishing rate of a large area of the surface of the polycrystalline silicon can be greatly higher than the polishing rate in the groove, thereby reducing the depression. A method of manufacturing a Flash is disclosed in US 2003/0216003 A1 and US 2004/0163324 A1. The invention comprises a polishing liquid for polishing polycrystalline germanium, the polishing liquid comprising at least one compound containing a -N(OH), -NH(OH), -NH2(OH) group, and a polycrystalline germanium and a cerium oxide using the slurry. The polishing selection ratio is greater than 50. US 2004/0123528 A1 discloses an acidic polishing liquid comprising abrasive particles and an anionic compound which can reduce the removal rate of the protective layer film and increase the removal rate selection ratio of the polycrystalline silicon and the protective layer film. US 2005/0130428 A1 and CN 1637102 A disclose a slurry for polycrystalline germanium chemical mechanical polishing comprising one or more nonionic surfactants forming a passivation layer on a polysilicon layer and a second passivation layer A second surfactant capable of reducing the rate of removal of tantalum nitride or yttria. Patent document US Pat. No. 6,191,039 discloses a chemical mechanical polishing method which can reduce the time and cost of chemical polishing and has a good flattening effect. Although the above technology achieves a certain degree of flattening effect to some extent, shortening the polishing time and cost, but it is either a two-step operation, or only suppresses the polishing rate of the polycrystalline silicon, which is not conducive to the removal of polycrystalline germanium in the dish of the cerium oxide dish. And the operation is complicated, and the polishing effect is limited.

The purpose of the present invention is to solve the above problem that the polycrystalline germanium/cerium oxide selective ratio is too high, and the residual polycrystalline germanium in the germanium dioxide dish-shaped recess is difficult to remove, and the polycrystalline germanium/cerium oxide is selected for polishing polycrystalline germanium. A chemical mechanical polishing fluid.

The polishing liquid of the present invention contains abrasive particles, at least one strontium accelerating agent, at least one hydrazine inhibitor, and water.

In the present invention, the growth accelerator of the ruthenium contains a sulfonium group ( )compound of.

The guanidine group-containing compound is a monoterpene, a biguanide, a polyfluorene compound and an acid addition salt thereof.

The monoterpenoids and acid addition salts thereof are preferably hydrazine, cesium carbonate, cesium acetate, cesium hydrogen phosphate, guanidine hydrochloride, guanidine nitrate, cesium sulfate, aminoguanidine, aminoguanidine hydrogencarbonate, aminoguanidine. Sulfonate, aminoguanidine nitrate or aminoguanidine hydrochloride.

The biguanide compound or an acid addition salt thereof is preferably biguanide, metformin, phenformin, 1,1'-hexylbis[5-(p-chlorophenyl)biguanide, morpholinium, acid of the above compound An addition salt or a 6-mercapto-2-naphthyl 4-mercaptobenzoate methanesulfonate; the acid is preferably hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid or sulfonic acid.

The polyfluorene or an acid addition salt thereof is preferably polyhexamethylene fluorene, polyhexamethylene biguanide, poly(hexamethylenebiscyanoguanidine-hexamethylenediamine) or an acid thereof. Addition salt. The acid is preferably hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid or sulfonic acid. The degree of polymerization of the polyfluorene compound or the acid addition salt thereof is preferably from 2 to 100.

The content of the growth accelerating agent of the crucible in the solution is preferably 0.0001 to 10% by weight, more preferably 0.001 to 3% by weight.

In the present invention, the inhibitor of ruthenium is a quaternary ammonium salt type cationic surfactant.

The quaternary ammonium salt type cationic surfactant is a quaternary ammonium salt cationic surfactant containing at least one N+ in the molecule. Preferred are single quaternary ammonium salt type and/or Gemini quaternary ammonium salt cationic surfactants.

In the present invention, the monoquaternary ammonium salt type cationic surfactant is R ₁ R ₂ N ⁺ R ₃ R ₄ X ^- , wherein: at least one of R ₁ , R ₂ , R ₃ and R ₄ is - C _m H _2m+1 or -C _m H _2m+1 O(CH ₂ CHO) _n ,8 m 22, n>3; the rest are C ₁ -C ₄ alkyl, -CH ₂ -C ₆ H ₅ , CH ₂ CH ₂ OH or CH ₂ CH ₂ CHOH, R ₁ , R ₂ , R ₃ , R ₄ The same or different; X is Cl ^- , Br ^- , CH ₃ SO ₄ ^- , NO ₃ ^- or C ₆ H ₅ -SO ₄ ^- .

The gemini quaternary ammonium salt cationic surfactant is (R ₁ R ₂ N ⁺ R _{2 -} R _{4 -} R ₃ R ₂ N ⁺ R ₂ ) 2X ^- , wherein: R ₁ is -C _m H _{2m+ 1} , 8 m 18; R ₂ is -CH ₃ or -C ₂ H ₅ ; R _{3 is the} same as R ₁ or R ₂ ; R ₄ is phenyl dimethylene, CH ₂ CH(OH)CH ₂ , polymethylene-(CH ₂ ) _n -, 2 n 30, or polyoxyethylene-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _n -,1 n 30; X ^- is Cl ^- or Br ^- .

In the present invention, the concentration of the quaternary ammonium salt type cationic surfactant is preferably from 0.0001 to 5%, more preferably from 0.001 to 1%.

In the present invention, the abrasive particles are commonly used in the art as abrasive particles of cerium oxide, aluminum oxide, aluminum-doped cerium oxide, aluminum-coated cerium oxide, cerium oxide, titanium dioxide and polymer abrasive particles. One or more.

The content of the abrasive particles is 0.1 to 30 wt% by weight.

The particle size of the abrasive particles is preferably from 20 to 150 nm, more preferably from 30 to 120 nm.

The pH of the polishing liquid of the present invention is preferably from 7 to 12.

The polishing liquid of the present invention may further contain a conventional acidic pH adjuster such as H2SO4 or HNO3, a viscosity modifier and/or an antifoaming agent, etc., by which the characteristics such as pH and viscosity of the polishing liquid are controlled.

The polishing liquid of the present invention is obtained by simply mixing and mixing the above components.

The polishing liquid of the invention can be prepared by concentration, and can be uniformly mixed by adding deionized water during use.

The positive progress of the present invention is that the polishing liquid of the present invention can better polish single crystal germanium and polycrystalline germanium films under alkaline conditions. Among them, the antimony inhibitor can significantly reduce the removal rate of polycrystalline germanium without reducing the removal rate of ceria, thereby significantly reducing the selectivity ratio of polycrystalline germanium to ceria; the antimony accelerating agent can dissolve the polycrystalline germanium and carry away the polishing residue. Avoid re-adsorption on the wafer or polishing pad. By adjusting the amount of the ruthenium accelerating agent and the ruthenium inhibitor, a polishing liquid having a suitable polycrystalline ruthenium/cerium oxide selectivity ratio can be obtained. Compared with the prior art, the polishing solution better solves the problem of the occurrence of polycrystalline disc-shaped depressions in the ceria channel and the residual polysilicon in the ceria dish-shaped depressions in the prior polycrystalline germanium polishing process. High flatness can be achieved by one-step polishing without polysilicon residue, and a wafer structure as shown in FIG. 3 can be obtained after polishing. The new use of the invention also has the characteristics of wide process window, which can greatly improve the productivity and greatly reduce the production cost. At the same time, the quinone compound also has a pH adjusting effect, so that the polishing liquid of the present invention does not need to add a conventional alkaline pH adjusting agent (organic hydrazine such as KOH and/or an organic amine such as ammonia water, etc.), thereby greatly reducing metal ion pollution and environmental pollution.

The invention is further illustrated by the following examples.

detailed description

The invention is further illustrated by the following examples, which are not intended to limit the invention.

Example 1 Polycrystalline germanium chemical mechanical polishing liquid

Table 1 shows the formulations of the chemical mechanical polishing liquids 1 to 22 of the present invention, and the polishing liquids of the respective examples are obtained by uniformly mixing the components and their contents given in the table, and the water is the balance.

Effect Example 1

Table 2 shows the formulation and polishing effect of the comparative polishing liquid 1 to 2 and the polishing liquid 23 to 29, and the polishing liquids of the respective examples are obtained by uniformly mixing the components and the contents thereof given in the table, and the water is the balance.

The polishing process parameters were: 3 psi under pressure, 70 rpm for polishing disc (14 inches in diameter), 80 rpm for polishing head, 200 ml/min for polishing fluid, PPG fast pad CS7, and Logitech LP50 polishing machine. The polishing material is an empty polycrystalline silicon wafer and an empty germanium dioxide wafer.

It can be seen from the data in Table 2 that the polishing liquids 23-29 of the present invention significantly reduce the removal rate of polycrystalline germanium and have little effect on the removal rate of cerium oxide, thereby reducing the polycrystalline germanium and cerium oxide, compared with the comparative polishing liquid 1. Choose ratio. In the case where the other components and their contents are the same, the addition of the guanidines guanidines compound will slightly increase the removal rate of polycrystalline lanthanum, but its effect on the polishing rate is much less than that of the cerium inhibitor quaternary ammonium salt. Active agent. Therefore, the polycrystalline cerium/cerium oxide selectivity of the polishing liquid can be adjusted by the content of the quaternary ammonium salt surfactant and the quinone compound.

Effect Example 2

A patterned polycrystalline silicon wafer is used with contrast polishing liquid 2 and polishing liquid 23. The residual removal of polycrystalline germanium in the dishing of the cerium oxide after polishing was observed.

The polishing process parameters were: 3 psi under pressure, 70 rpm for polishing disc (14 inches in diameter), 80 rpm for polishing head, 200 ml/min for polishing fluid, PPG fast pad CS7, and Logitech LP50 polishing machine.

The polishing effect shows that the bismuth speed increasing agent is added to the polishing liquid 23 of the present invention in comparison with the comparative polishing liquid 2, so that the polishing liquid of the present invention does not excessively inhibit the removal rate of the polycrystalline silicon, and contributes to the removal of the samarium dioxide dish-shaped depression. The polycrystalline germanium remains.

The compounds mentioned in the present invention are all commercially available.

Figure 1 is a diagram showing the structure of a wafer before (a) and after polishing (b) in a conventional polysilicon polishing process.

Figure 2 is a schematic view of the disk shape of the ceria surface caused by shallow channel isolation (STI) chemical mechanical polishing, before (a) and (b) before the polysilicon polishing process.

Figure 3 is a diagram showing the structure of a wafer which can be obtained after polishing using the novel use of the present invention.

Claims (13)

A polishing chemical mechanical polishing slurry comprising: water, abrasive particles, at least one strontium accelerating agent, and at least one cerium inhibitor, wherein the cerium inhibitor is a quaternary ammonium salt type cationic surfactant The growth accelerating agent of the hydrazine is biguanide, polyfluorene compound and acid addition salt thereof, and the biguanide compound or acid addition salt thereof is biguanide, metformin, phenformin, 1,1'-hexyl double [5-(p-chlorophenyl) biguanide, morpholinium, an acid addition salt of the above compound and/or 6-fluorenyl-2-naphthyl 4-mercaptobenzoate methanesulfonate; The acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and/or sulfonic acid, and the polyfluorene or its acid addition salt is polyhexamethylene fluorene, polyhexamethylene biguanide, poly(hexamethylene Dicyanoguanidine-hexamethylenediamine) and/or an acid addition salt thereof; the acid is hydrochloric acid, phosphoric acid, nitric acid, acetic acid, gluconic acid and/or sulfonic acid; the polyfluorene compound or The degree of polymerization of the acid addition salt is from 2 to 100. The solution according to claim 1, wherein the stimulating agent of the cerium is contained in the solution in an amount of 0.0001 to 10% by weight. The polishing liquid according to claim 1, wherein the quaternary ammonium salt type cationic surfactant is a quaternary ammonium salt cationic surfactant containing at least one N+ in the molecule. The polishing liquid according to claim 1, wherein the quaternary ammonium salt type cationic surfactant is a monoquaternary ammonium salt type and/or a gemini type quaternary ammonium salt cationic surfactant. The polishing liquid according to claim 3, characterized in that the monoquaternary ammonium salt type cationic surfactant is R ₁ R ₂ N ⁺ R ₃ R ₄ X ^- , wherein: R ₁ , R ₂ , R ₃ At least one of R ₄ is -C _m H _2m+1 or -C _m H _2m+1 O(CH ₂ CHO) _n ,8 m 22, n>3; the rest are C ₁ -C ₄ alkyl, -CH ₂ -C ₆ H ₅ , CH ₂ CH ₂ OH or CH ₂ CH ₂ CHOH, R ₁ , R ₂ , R ₃ , R _{4 are the} same Or different; X ^- is Cl ^- , Br ^- , CH ₃ SO ₄ ^- , NO ₃ ^- or C ₆ H ₅ -SO ₄ ^- . The polishing liquid according to claim 3, characterized in that the gemini-type quaternary ammonium salt cationic surfactant is (R ₁ R ₂ N ⁺ R _{2 -} R _{4 -} R ₃ R ₂ N ⁺ R ₂ ) 2X ^- , where: R ₁ is -C _m H _2m+1 ,8 m 18; R ₂ is -CH ₃ or -C ₂ H ₅ ; R _{3 is the} same as R ₁ or R ₂ ; R ₄ is phenyl dimethylene, CH ₂ CH(OH)CH ₂ , polymethylene-(CH ₂ ) _n -, 2 n 30, or polyoxyethylene-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _n -,1 n 30; X ^- is Cl ^- or Br ^- . The polishing liquid according to claim 1, wherein the quaternary ammonium salt type cationic surfactant has a concentration by weight of 0.0001 to 5%. The polishing liquid according to claim 7, wherein the quaternary ammonium salt type cationic surfactant has a concentration by weight of 0.001 to 1%. The polishing liquid according to claim 1, wherein the abrasive particles are cerium oxide, aluminum oxide, aluminum-doped cerium oxide, aluminum-coated cerium oxide, cerium oxide, titanium oxide, and polymer. One or more of the abrasive particles. The polishing liquid according to claim 1, wherein the abrasive particles are contained in an amount of 0.1 wt.% to 30 wt.% by weight. The chemical mechanical polishing liquid according to claim 1, characterized in that: The abrasive particles have a particle size of 20 to 150 nm. The chemical mechanical polishing liquid according to claim 11, wherein the abrasive particles have a particle diameter of 30 to 120 nm. The polishing liquid according to claim 1, characterized in that the polishing liquid is used for polishing involving single crystal germanium and polycrystalline germanium.