Chemical mechanical polishing slurry, cmp process and electronic device process

Abstract

To provide a slurry for Chemical Mechanical Polishing, a Chemical Mechanical Polishing method using said slurry, and a method of producing electronic devices using said method that makes it possible to achieve a low scratch process capability in processing surfaces such as SiO2 film surfaces and the like and also to enable speed polishing to attain a high processing efficiency.Slurry for Chemical Mechanical Polishing characterized in comprising abrasive grains and water, wherein said abrasive grains are composite particles coated with ceria particles consisting of organic host particles and ceria particles, zeta potential of said composite particles being a negative potential, the organic host particles constituting the composite particles coated with ceria particles are organic host particles to which carboxyl groups and sulfonyl groups are introduced; the slurry is added with panarization additive; and the planarization additive is poly(methyl)acrylic acid ammonium salt.

Description

FIELD OF THE INVENTION[0001]The invention pertains to the slurry used in the Chemical Mechanical Polishing (“CMP”) process, which is essential to the Shallow Trench Isolation (“STI”) method applied in the producing process of semiconductor devices, the CMP method using said slurry, and the method of producing electronic devices using said method, in particular, said method applied to achieve a low-scratch finish on workpieces being polished and high process efficiency simultaneously, as well as to achieve high planarity on the processed surface of the workpieces.DESCRIPTION OF THE RELATED ART[0002]Because of a trend in the design of semiconductor devices toward minute and multi-layer structures, the element removal method is making a shift from the LOCOS (Local Oxidation of Silicon) technology, in which the nitride film of the silicon surface is removed by oxidizing a portion of the surface, to the STI technology, which makes higher integration possible. The STI technology is a meth...

AI Technical Summary

Benefits of technology

[0038]While the inorganic particles constituting the composite particles that are used as the abrasive grains of the present invention can be either cerium oxide (CeO2), manganese sesquioxide (Mn2O3) or cerium hydroxide (Ce(OH)4), the abrasive grains made of ceria particles, i.e., cerium oxide, have advantages that they have an excellent polishing capability against the silicon oxide film and that it is easy to achieve the sufficient polishing selectivity (polishing speed ratio of SiO2 / Si3N4) between the silicon oxide film and the silicon nitride (Si3N4), which is used as the stopper film in the STI-CMP process, with the use of the planarization additives. The average particle diameter of the inorganic guest particles of the present invention is preferably within the range of 10-500 nm. The reason is that it causes a problem that the polishing speed drops if the average diameter the inorganic guest particles is less than 10 nm and a problem that the scratches on the workpiece increase if the average diameter of the inorganic guest particles exceeds 500 nm. While inorganic particles are generally produced by either the chemical vapor deposition method or the wet process, the inorganic particles of the present invention are preferably produced by the chemical vapor deposition method considering the productivity as the composite particles of the present invention are produced by the dry complex method. Moreover, since the higher the surface coverage ratio of the organic host particles by the inorganic particles, the higher the speed of polishing can be, the surface coverage ratio should preferably be higher than 20%.

[0044]The slurry for Chemical Mechanical Polishing (CMP) according to the present invention is capable of sustaining high polishing speeds and providing a sufficient polishing selectivity for achieving the planarity of the surface being processed even if the planarization additives (C) are not added by using the composite particles with a negative zeta potential as the abrasive particles. While the polishing speed drops substantially if the zeta potential of the composite particles, i.e., abrasive grains, is a positive potential, as it causes excessive adherence of planarization additives (C) even though the planarization additives are added, the slurry for CMP according to the present invention makes it possible to suppress the adherence of the planarization additives (C), thus achieving both a high polishing speed and a sufficient polish selectivity by means of using the composite particles with a negative zeta potential as the abrasive grains.

[0045]The method of producing electronic devices using the slurry for CMP consisting of abrasive grains (A) and water (B), the CMP method using said slurry, and the method of producing electronic devices using said method all according to the present invention achieve low scratch characteristics on the surface being polished in the CMP process and a high process efficiency due to a high speed polishing process as a result of using the composite particles coated with ceria particles consisting of organic host particles and ceria particles as said abrasive grains (A), wherein the zeta potential of said composite particles is a negative potential.

[0046]In addition to the above effect, the method of producing electronic devices using the slurry for CMP, the CMP method using said slurry, and the method of producing electronic devices using said method according to the present invention provide an effect of achieving the planarity of the surface being polished as well by adding the planarization additives (C) to said slurry for CMP.

Problems solved by technology

The slurry being used in the CMP typically consists of colloidal silica and fumed silica abrasive grains dispersed in an alkali-based solution and is applied in polishing an object by mechanical polishing by means of silica (SiO2) and a chemical etching effect, but it has many problems related to the planarity of the surface being processed, scratches, finish point control in polishing, etc.

There is a tendency in the process of producing semiconductor devices in recent years that abrasive grains used for the polishing process are becoming increasingly minute while the demand for low scratchiness is intensifying, which in turn is degrading the polishing process efficiency.

The abrasive grains produced by this method is electrostatically compounded so that the adhesive strength of the inorganic particles to the organic particles is weak and the inorganic particles tend to drop off easily, thus making it difficult to sustain sufficient polishing speeds.

Furthermore, there is also a problem that any additives applied for planarization of the polish-processed surface (hereinafter called “planarization additives”) weaken the electrostatic actions between the particles thus degrading the compounding effect.

In the meanwhile, another method has been proposed using a mixture of organic and inorganic particles, but it has a problem that sufficient polishing speeds are not achievable as organic particles are not compounded thus acting as a hindrance factor in polishing.

Although the planarization additives provide an advantage that it makes it easier to achieve planarity and uniformity of the workpieces being polished because of the polishing selectivity between the silicon oxide film and the silicon nitride film, which is the polishing stopper filme, it also presents a problem of affecting the polishing speed because the planarization additives work to protect the workpieces from being polished.

However, this method has a problem that polish selectivity is completely inactive unless planarization additives are added and that grinding speed drops substantially if planarization additives are added.