Chemical-mechanical polishing solution having high silicon nitride selectivity

Abstract

A chemical-mechanical polishing slurry having high Silicon Nitride removal rate selectivity includes abrasive particles and a compound containing one or more carboxyl groups. The polishing slurry has high SiN removal rate, low TEOS removal rate, and high removal rate selectivity of SiN to TEOS. The polishing slurry can significantly reduce the defects on Oxide surface which has an excellent market application prospect.

Claims

1. A chemical-mechanical polishing slurry consisting of silica particles, a compound containing one or more carboxyl groups, a pH adjustor, and water, wherein the compound containing one or more carboxyl groups is selected from the group consisting of a pyridine compound, a piperidine compound, a pyrrolidine compound, a pyrrole compound, and any derivative and/or combination thereof.

2. The chemical-mechanical polishing slurry as claimed in claim 1, wherein the compound containing one or more carboxyl groups is selected from the group consisting of 2-carboxyl pyridine, 3-carboxyl pyridine, 4-carboxyl pyridine, 2,3-dicarboxyl pyridine, 2,4-dicarboxyl pyridine, 2,6-dicarboxyl pyridine, 3,5-dicarboxyl pyridine, 2-carboxyl piperidine, 3-carboxyl piperidine, 4-carboxyl piperidine, 2,3-dicarboxyl piperidine, 2,4-dicarboxyl piperidine, 2,6-dicarboxyl piperidine, 3,5-dicarboxyl piperidine, 2-carboxyl pyrrolidine, 3-carboxyl pyrrolidine, 2,4-dicarboxyl pyrrolidine, 2,5-dicarboxyl pyrrolidine, 2-carboxyl pyrrole, 3-carboxyl pyrrole, 2,5-dicarboxypyrrole, and 3,4-dicarboxypyridine.

3. The chemical-mechanical polishing slurry as claimed in claim 1 wherein the pH value of the chemical-mechanical polishing slurry is 1.5 units higher than the pKa1 of the compound containing one or more carboxyl groups and lower than 6.5.

4. The chemical-mechanical polishing slurry as claimed in claim 1, wherein the mass percentage concentration of the silica particles is from 0.5 wt % to 8 wt %.

5. The chemical-mechanical polishing slurry as claimed in claim 4, wherein the mass percentage concentration of said silica particles is from 1 wt % to 5 wt %.

6. The chemical-mechanical polishing slurry as claimed in claim 1 wherein the mass percentage concentration of said compound containing one or more carboxyl groups is from 0.01 wt % to 0.5 wt %.

7. The chemical-mechanical polishing slurry as claimed in claim 6 wherein the mass percentage concentration of the compound containing one or more carboxyl groups is from 0.01 wt % to 0.3 wt %.

8. A chemical-mechanical polishing slurry consisting of silica particles, a compound containing one or more carboxyl groups, a pH adjustor, water, and a bactericide, wherein the compound containing one or more carboxyl groups is selected from the group consisting of a pyridine compound, a piperidine compound, a pyrrolidine compound, a pyrrole compound, and any derivative and/or combination thereof.

9. The chemical-mechanical polishing slurry as claimed in claim 8, wherein the pH adjustor is selected from the group consisting of HNO.sub.3, KOH, K.sub.2HPO.sub.4, KH.sub.2PO.sub.4, and combinations thereof.

10. The chemical-mechanical polishing slurry as claimed in claim 8, wherein the bactericide is selected from the group consisting of 5-chloro-2-methyl-4-isothiazolin-3-ketone (CIT), 2-methyl-4-isothiazolinone (MIT), 1,2-Phenylpropanzothiazolinone (BIT), Iodopropargyl carbamate (IPBC), 1,3-dihydroxymethyl-5,5-methyl-heine (DMDMH), and combinations thereof.

11. The chemical-mechanical polishing slurry, as claimed in claim 8 wherein the mass percentage concentration of the bactericide is from 0.02 wt % to 0.2 wt %.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The formulas of embodiments and the comparative examples are given in table 1. All components are dissolved and mixed well with water to form 100% solution and pH of the mixture is adjusted to target by pH adjustor.

(2) TABLE-US-00001 TABLE 1 Compositions of embodiments and comparative examples Abrasive Particles Carboxyl Compound Bactericide SiN TEOS SiN/TEOS concentration concentration concentration RR RR RR Name (%) Name Pka 1 (%) Name (%) pH (A/min) (A/min) selectivity Comparative SiO.sub.2 3 2.5 23 623 0.04 example 1 Comparative SiO.sub.2 3 Hydroxyethyl 1.2 0.05 2.5 405 426 0.95 example 2 1, 1-diphosphate Comparative SiO.sub.2 3 Ascorbic 4.19 0.05 2.5 325 401 0.81 example 3 acid Comparative SiO.sub.2 3 2-carboxyl 1.0 0.05 2.5 256 611 0.42 example 4 pyridine Embodiment 1 SiO.sub.2 3 2-carboxyl 1.0 0.05 CIT 0.02 4 612 19 32.21 pyridine Embodiment 2 SiO.sub.2 0.5 2,6-dicarboxyl 2.1 0.01 BIT 0.05 5.2 451 14 32.21 pyridine Embodiment 3 SiO.sub.2 1 3-carboxyl 2.0 0.05 MIT 0.10 4.5 563 15 37.53 piperidine Embodiment 4 SiO.sub.2 5 2,4-dicarboxyl 2.1 0.04 IPBC 0.20 5.6 654 21 31.14 piperidine Embodiment 5 SiO.sub.2 6 2-carboxyl 1.7 0.30 DMDMH 0.20 6 672 17 39.53 pyrrolidine Embodiment 6 SiO.sub.2 8 2,5-dicarboxyl 2.5 0.03 MIT 0.05 4.8 715 23 31.09 pyrrolidine Embodiment 7 SiO.sub.2 2 2-carboxyl 1.6 0.10 BIT 0.02 5 605 16 37.81 pyrrole Embodiment 8 SiO.sub.2 2 2,5-dicarboxypyrole 2.6 0.05 DMDMH 0.02 5.3 587 15 39.13 Embodiment 9 SiO.sub.2 2 2-carboxyl 1.0 0.50 DMDMH 0.02 4.3 664 18 36.89 pyrrolidine Embodiment SiO.sub.2 2 2-carboxyl 1.0 0.05 DMDMH 0.02 6.5 475 20 23.75 10 pyridine

(3) The polishing slurry formulated in table 1 was tested according to the following experimental conditions.

(4) Specific polishing conditions: Polisher: Mirra Pad: IC1010, platen/head rotation speed: 93/87 rpm, polishing pressure: 1.5 psi. Slurry flow rate is 150 ml/min. 8″ Silicon Nitride and TEOS wafers are polished for 1 min and then cleaned, dried and measured to get the polishing result.

(5) It can be seen from the results of comparative example 1 that Silicon Nitride removal rate (RR) is very low while TEOS RR is relatively high when using the Silica abrasive only. The selectivity of Silicon Nitride to TEOS is in the reverse direction. It can be seen from the results of embodiments and comparative example 2 and 3 that, compared with the slurry containing other carboxylic acids and other heterocyclic acids, the RR of Silicon Nitride of the present invention is significantly increased, the RR of TEOS is reduced and the RR selectivity of Silicon Nitride to TEOS is very high. According to the results of embodiments and comparative example 4, when the pH is 1.5 units higher than Pka1(1.0) of 2-carboxypyridine, Silicon Nitride RR is relatively high, while TEOS RR is relatively low, hence RR selectivity of Silicon Nitride to TEOS is high. The molecular structure of the carboxylic compound in this invention includes carboxyl and nitrogen structure at the same time, when the pH is 1.5 units higher than Pka1, nitrogen structure and the silica abrasive particles are mutually attracted so that the carboxyl structure is exposed. The carboxyl structure will enhance the interaction between abrasive particles and Silicon Nitride surface while reduce the interaction between the abrasive particles and TEOS surface. So Silicon Nitride RR is increased while TEOS RR is decreased. By using the polishing slurry with high selectivity of Silicon Nitride to TEOS, we can reduce the defects caused by Silicon Nitride as the stop layer in STI polishing process. In addition, in the structure where TEOS is used as the stop layer, using the polishing slurry in this invention can provide high removal efficiency of Silicon Nitride

(6) It should be noted that the embodiment of the present invention has better enforcement and there is no any limit to the present invention. Any technicians familiar with this field may use the above revealed technical content for equivalent embodiment by changing or modifying the embodiment of the present invention. If not out of range of the technology solution of the present invention, the changing, equivalent changing or modifying according to the technical essence of the present invention still belongs to the scope of the technology solutions of the present invention.