WO2008040158A1

WO2008040158A1 - A chemical-mechanical polishing liquid for polishing polysilicon

Info

Publication number: WO2008040158A1
Application number: PCT/CN2007/002716
Authority: WO
Inventors: Judy Jianfen Jing; Andy Chunxiao Yang
Original assignee: Anji Microelectronics (Shanghai) Co., Ltd.
Priority date: 2006-09-15
Filing date: 2007-09-14
Publication date: 2008-04-10
Also published as: CN101627097A; CN101143996A

Abstract

A chemical-mechanical polishing liquid for polishing polysilicon is disclosed, which comprises abrasive particles and water, and further comprises one or more kind of oxidizing agent. Under basic condition, the polishing liquid may significantly change removal rate of polysilicon, adjust selectivity ratio of polysilicon and SiO2, and obviously improve the planarization-efficiency of polysilicon and removal of polishing residues.

Description

Chemical mechanical polishing liquid for polishing polycrystalline silicon

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

In the manufacture of integrated circuits, the standard of interconnect technology is increasing, and a layer is deposited on top of one layer, so that an irregular topography is formed on the surface of the substrate. One method of planarization used in the prior art is chemical mechanical polishing (CMP), which uses a mixture of abrasives and chemicals and a polishing pad to polish a wafer 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 back side of the substrate with a load. During polishing, the gasket and the table rotate while maintaining a downward force on the back side of the substrate, applying an abrasive and a chemically active solution (commonly referred to as a polishing fluid or polishing slurry) to the gasket, the polishing fluid being The chemical film reaction of the film being polished begins the polishing process.

For the polishing of polysilicon, it is mainly applied to two kinds of chips, one is DRAM, the other is Flash. In the latter application, the polishing of silicon dioxide is often involved in the polishing of polysilicon.

In the past, in the case of using an alkaline slurry using silica as abrasive particles to polish the polysilicon layer and the silicon dioxide layer, the removal rate of the polysilicon tends to be much higher than the removal rate of the silicon dioxide, which tends to cause polysilicon. The excess is removed to create a depression that affects the subsequent process.

US 2003/0153189 A1 discloses a chemical mechanical polishing liquid and method for polysilicon 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 a polycarboxylate surfactant, which can be used to confirm the polysilicon The polishing rate of the large area of the surface is much higher than the polishing rate in the trench, 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 silicon, the polishing crucible comprising at least one compound containing a -N(OH), -NH(OH), -NH ₂ (OH) group, polycrystalline silicon and two using the slurry The polishing selectivity of silicon oxide is greater than 50. US 2004/0014321 A1 discloses an acidic polishing liquid comprising abrasive particles and an oxidizing agent, which can be used to increase the polishing selectivity of polycrystalline silicon to silicon dioxide. 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 selectivity ratio of the polycrystalline silicon to the protective layer film. US 2005/0130428 A1 and CN 1637102 A disclose a slurry for polysilicon chemical mechanical polishing comprising one or more nonionic surfactants forming a passivation layer on a polysilicon layer and an energy A second passivation layer is formed to reduce the rate of removal of silicon nitride or silicon oxide by the second surfactant. The nonionic surfactant comprises at least one compound selected from the group consisting of epoxy epoxide-propylene oxide block copolymer alcohol and ethylene oxide-glycidene triblock polymer, the slurry The selectivity between the polysilicon removal rate and the insulator removal rate can be reduced by at least about 50%. Summary of invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel chemical mechanical polishing liquid which can better polish a polycrystalline silicon film under alkaline conditions.

The above object of the present invention is achieved by the following technical solutions: The polishing liquid of the present invention comprises abrasive particles and water, and further comprises one or more oxidizing agents.

The oxidizing agent described in the present invention is preferably: I. Organic or inorganic compounds containing at least one peroxy group (- 0 - 0 ~ )

II. An organic or inorganic compound containing an element in the highest oxidation state.

More preferably, the oxidizing agent is: hydrogen peroxide and its derivatives, urea peroxide, peroxyformic acid, peracetic acid, persulfate, sodium percarbonate, periodic acid and its salts, perchloric acid and its salts Or one or more of perboric acid and its salts.

The concentration percentage of the oxidizing agent of the present invention is preferably 0.1 to 30% _;

More preferably 0.5 to 20%.

The polishing liquid preferably has a pH of 7 to 12.

The abrasive particles described in the invention are silica, alumina, ceria, titania, aluminum-coated silica, aluminum-doped silica, and/or polymer abrasive particles.

The particle size of the abrasive particles is preferably from 30 to 150 nm _;

More preferably, it is 30 to 120 nm.

The concentration concentration of the abrasive particles is preferably 0.5 to 30% _;

More preferably 2 to 30%.

The slurry of the present invention may further contain a pH adjuster, a viscosity modifier, a bactericide or the like to attain the effects of the present invention.

The positive progressive effect of the present invention is that the polishing liquid of the present invention can significantly change the removal rate of polycrystalline silicon under alkaline conditions, adjust the selectivity ratio of polycrystalline silicon to silicon dioxide, and significantly improve the planarization efficiency of polycrystalline silicon and the removal of polishing residues. . Summary of the invention

Example 1 Contrast polishing liquid silica (100nm) 15%, water balance, PH value 11.2;

The polishing rate of polycrystalline silicon is 3330 A/min, and the polishing rate of silicon dioxide is 521 A/min. The selectivity ratio of the two is 5.38. Polishing solution 1 silica (120nm) 15%, hydrogen peroxide 0.5%, water balance, pH 11.2; polysilicon polishing rate is 1866 A / min, silica polishing rate is 482 A / min, two The choice ratio is 3.87.

Polishing solution 2 silica (100nm) 15%, hydrogen peroxide 2%, water balance, pH 11.2; polysilicon polishing rate is 1747 A / min, silica polishing rate is 543 A / min, two The choice ratio is 3.22.

Polishing solution 3 silica (100nm) 15%, hydrogen peroxide 5%, water balance, pH 11.2; polysilicon polishing rate is 950 A / min, silica polishing rate is 560 A / min, two The choice ratio is 1.70.

Polishing solution 4 silica (100nm) 15%, hydrogen peroxide 15%, water balance, pH 11.2; polysilicon polishing rate is 711 A / min, silica polishing rate is 580 A / min, two The choice ratio is 1.23.

Polishing solution 5 silica (100nm) 15%, hydrogen peroxide 20%, water balance, pH 11.2; polysilicon polishing rate is 537 A / min, silica polishing rate is 572 A / min, two The choice ratio is 0.94.

The process parameters for polishing 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. Example 2

Comparative polishing solution 2' silica (100nm) 10%, water balance, PH value of 11.2;

The polishing rate of polycrystalline silicon is 2002 A/min, and the polishing rate of silicon dioxide is 375 A/min. The selectivity ratio of the two is 5.34. Polishing solution 6 silicon dioxide (100nm) 10%, hydrogen peroxide 5%, water balance, PH value 7; polysilicon throw rate is 572 A / min, silica polishing rate is 151 A / min, two The choice ratio is 3.79.

Polishing solution 7 silicon dioxide (100nm) 10%, hydrogen peroxide 5%, water balance, PH value 10; polysilicon polishing rate is 739 A / min, silica polishing rate is 286 A / min, two The choice ratio is 2.58.

Polishing solution 8 silica (10011111) 10%, hydrogen peroxide 5%, water balance, pH 11.2; polysilicon polishing rate is 815A / min, silica polishing rate is 379 A / min, both The choice ratio is 2.15.

Polishing solution 9 silicon dioxide (100nm) 10%, hydrogen peroxide 5%, water balance, PH value 12; polysilicon polishing rate is 883 A / min, silica polishing rate is 484 A / min, two The choice ratio is 1.82.

The process parameters for polishing 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. Example 3 Polishing solution 10 silica (100nm) 2%, hydrogen peroxide 5%, water balance, PH value 11.2; polysilicon polishing rate is 568 A / min, silica polishing rate is 160 A / min, two The choice ratio is 3.55.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 4

Polishing solution 11 silica (100nm) 30%, hydrogen peroxide 5%, water balance, pH 11.2; polysilicon polishing rate is 1352 A / min, silica polishing rate is 916 A / min, two The choice ratio is 1.48.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 5

Polishing solution 12 silica (100nm) 10%, peroxyacetic acid 1%, water balance, PH value 11.2; polysilicon polishing rate is 928 A / min, silica polishing rate is 391 A / min, two The choice ratio is 2.37.

The process parameters for polishing 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. Example 6

Polishing solution 13 silicon dioxide (100nm) 10%, ammonium persulfate 1%, water balance, PH value 11.2; polysilicon polishing rate is 1885 A / min, silica polishing rate is 413 A / min, two The choice ratio is 4.56.

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

Example 7

Polishing solution 14 titanium dioxide (150nm) 10%, potassium peroxide 0.1%, water balance, PH value 11.2; polysilicon polishing rate is 1232 A / min, silica polishing rate is 954 A / min, both The selection ratio is 1.29.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 8

Polishing solution 15 aluminum oxide (30nm) 30%, sodium percarbonate 30%, water balance, PH value 11.2; polysilicon polishing rate is 2031 A / min, silica polishing rate is 2305 A / min, The choice between the two is 0.88.

The process parameters for polishing 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 liquid 16 is doped with aluminum silica (30 nm) 30%, peroxyformic acid 30%, water balance, PH value 11.2;

The polishing rate of polycrystalline silicon was 1857 A/min, and the polishing rate of silicon dioxide was 2159 A/min. The selectivity ratio of the two was 0.86.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 10

The polishing liquid 17 is covered with aluminum silica (45 nm) 10%, sodium perborate and urea peroxide 10%, water balance, pH value 11.2;

The polishing rate of polysilicon is 962 A/min, the polishing rate of silicon dioxide is 846 A/min, and the selection ratio of the two is 1.14.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 11

Polishing solution 18 silica (70nm) 10%, periodic acid and potassium perchlorate 10%, water balance, PH value 11.2;

The polishing rate of polysilicon is 886 A/min, and the polishing rate of silicon dioxide is 480 A/min, two The choice ratio is 1.85.

The process parameters for polishing were: 3 psi downforce, 70 rpm polishing disc (14 inches diameter), 80 rpm polishing head speed, 200 ml/min polishing fluid flow rate, PPG fast pad CS7 polishing pad, and Logitech LP50 polishing machine. Example 12

Polishing solution 19 cerium oxide (50nm) 0.5%, hydrogen peroxide 10%, water balance, PH value 11.2; polysilicon polishing rate is 693 A / min, silica polishing rate is 257 A / min, two The choice ratio is 2.70.

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

Claims

Rights request

A chemical mechanical polishing liquid for polishing polycrystalline silicon, the polishing liquid comprising abrasive particles and water, characterized by: further comprising one or more oxidizing agents.

2. The polishing liquid according to claim 1, wherein: said oxidizing agent is:

I. A compound containing at least one peroxy group (-O-O^);

II. A compound containing an element in the highest oxidation state.

3. The polishing liquid according to claim 2, wherein: the oxidizing agent is: hydrogen peroxide and a derivative thereof, urea peroxide, peroxyformic acid, peracetic acid, persulfate, sodium percarbonate, One or more of periodic acid and its salts, perchloric acid and its salts or perboric acid and its salts.

The polishing liquid according to any one of claims 1 to 3, wherein the oxidizing agent has a concentration by weight of 0.1 to 30%.

The polishing liquid according to claim 4, wherein the oxidizing agent has a weight percentage of 0.5 to 20% by weight.

The polishing liquid according to any one of claims 1 to 3, wherein the polishing liquid has a pH of 7 to 12.

The polishing liquid according to any one of claims 1 to 3, wherein: the abrasive particles are silica, alumina, cerium oxide, titanium dioxide, aluminum-coated silica, doping Aluminum silica and/or polymer abrasive particles.

The polishing liquid according to claim 7, wherein the abrasive particles have a particle diameter of 30 to 150 nm.

9. The polishing liquid according to claim 8, wherein: the abrasive particle size is

The polishing liquid according to claim 7, wherein the abrasive particles have a weight percentage of 0.5 to 30% by weight.

The polishing liquid according to claim 10, wherein the abrasive particles have a concentration by weight of 2 to 30%.