Abrasive, method of polishing target member and process for producing semiconductor device

• US 20060248804A1
• Filed: 07/12/2006
• Published: 11/09/2006
• Est. Priority Date: 12/18/1997
• Status: Active Grant

• Current Assignee: Hiroki Terazaki, Jun Matsuzawa, Kiyohito Tanno, Masato Yoshida, Toranosuke Ashizawa, Yasushi Kurata, Yuuto Ootuki
• Original Assignee: Hiroki Terazaki, Jun Matsuzawa, Kiyohito Tanno, Masato Yoshida, Toranosuke Ashizawa, Yasushi Kurata, Yuuto Ootuki
• Inventors: Ootuki, Yuuto, Yoshida, Masato, Tanno, Kiyohito, Matsuzawa, Jun, Terazaki, Hiroki, Ashizawa, Toranosuke, Kurata, Yasushi
• Granted Patent: US 7,871,308 B2
• Time in Patent Office: Days
• US Class Current: 51/309
• CPC Class Codes: C09G 1/02 containing abrasives or grinding agents abrasives as such C09K3/14; polishing of semi-conductors H01L
• CPC Class Codes: C09K 3/1409 Abrasive particles per se preparation of diamond C01B32/25
• CPC Class Codes: C09K 3/1463 Aqueous liquid suspensions
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step

Abstract

To polish polishing target surfaces of SiO₂ insulating films or the like at a high rate without scratching the surface, the present invention provides an abrasive comprising a slurry comprising a medium and dispersed therein at least one of i) cerium oxide particles constituted of at least two crystallites and having crystal grain boundaries or having a bulk density of not higher than 6.5 g/cm³ and ii) abrasive grains having pores. Also provided are a method of polishing a target member and a process for producing a semiconductor device which make use of this abrasive.

Claims

1. An abrasive comprising a slurry including a medium and cerium oxide particles dispersed in said medium, said cerium oxide particles constituted of at least two crystallites and having crystal grain boundaries.

2. The abrasive according to claim 1, wherein said cerium oxide particles having crystal grain boundaries have diameters with a middle value of from 60 nm to 1,500 nm.

3. The abrasive according to claim 1, wherein said cerium oxide particles having crystal grain boundaries have diameters with a middle value of from 100 nm to 1,200 nm.

4. The abrasive according to claim 1, wherein said cerium oxide particles having crystal grain boundaries have diameters with a middle value of from 300 nm to 1,000 nm.

5. The abrasive according to claim 4, wherein said crystallites have diameters with a middle value of from 10 nm to 50 nm.

6. The abrasive according to claim 4, wherein said crystallites have diameters with a middle value of from 50 nm to 200 nm.

7. The abrasive according to claim 1, wherein said crystallites have diameters with a middle value of from 5 nm to 250 nm.

8. The abrasive according to claim 1, wherein said crystallites have diameters with a middle value of from 5 nm to 150 nm.

9. The abrasive according to claim 1, wherein said cerium oxide particles having crystal grain boundaries have a maximum diameter not larger than 3,000 nm.

10. The abrasive according to claim 1, wherein said crystallites have a maximum diameter not larger than 600 nm.

11. The abrasive according to claim 1, wherein said medium is water.

12. The abrasive according to claim 1, wherein said slurry contains a dispersant.

13. The abrasive according to claim 12, wherein said dispersant is at least one selected from a water-soluble organic polymer, a water-soluble anionic surfactant, a water-soluble nonionic surfactant and a water-soluble amine.

14. The abrasive according to claim 13, wherein said dispersant is a polyacrylic acid polymer.

15. The abrasive according to claim 1, wherein:

cerium oxide particles with a diameter not smaller than 1 μ

m occupies at least 0.1% by weight of the total weight of the cerium oxide particles; and

said cerium oxide particles having crystal grain boundaries have a characteristic of polishing a target member while collapsing.

16. The abrasive according to claim 1, wherein said cerium oxide particles having crystal grain boundaries have a characteristic of polishing a target member while forming new surfaces not coming into contact with any medium.

17. The abrasive according to claim 1, wherein content of cerium oxide particles having a particle diameter not smaller than 0.5 μ

m after polishing, measured by centrifugal sedimentation after a target member has been polished, is in a ratio of not more than 0.8 with respect to that content before polishing.

18. The abrasive according to claim 1, wherein cerium oxide particle diameter at D99% by volume measured by laser diffraction after a target member has been polished is in a ratio of from 0.4 to 0.9 with respect to that particle diameter before polishing.

19. The abrasive according to claim 1, wherein cerium oxide particle diameter at D90% by volume measured by laser diffraction after a target member has been polished is in a ratio of from 0.7 to 0.95 with respect to that particle diameter before polishing.

20. A method of polishing a target member, comprising polishing a target member by the use of the abrasive according to claim 1.

21. The method of polishing a target member according to claim 20, wherein said target member has a strength higher than the grain boundary breaking strength of the cerium oxide particles.

22. The method of polishing a target member according to claim 20, wherein said target member is a semiconductor chip on which a silica film has been formed.

23. A process for producing a semiconductor device, comprising the step of polishing a semiconductor chip on which a silica film has been formed, by the use of the abrasive according to claim 1.

24. An abrasive comprising a slurry including a medium and abrasive grains having pores which are dispersed in said medium.

25. The abrasive according to claim 24, wherein said abrasive grains have a porosity of from 10% to 30% as determined from a ratio of a true density measured with a pycnometer to a theoretical density determined by X-ray Rietvelt analysis.

26. The abrasive according to claim 24, wherein said abrasive grains have a pore volume of from 0.02 cm³/g to 0.05 cm³/g as measured by the B.J.H. method.

27. The abrasive according to claim 24, wherein said abrasive grains are cerium oxide particles.

28. An abrasive comprising a slurry including a medium and dispersed therein cerium oxide particles having a bulk density not higher than 6.5 g/cm³.

29. The abrasive according to claim 28, wherein said bulk density is from 5.0 g/cm³ to 5.9 g/cm³.