TWI573847B - Chemical mechanical polishing liquid (a) - Google Patents

Description

Chemical mechanical polishing liquid (1)

The present invention relates to a chemical mechanical polishing liquid.

The planarization of copper interconnects typically employs a three-step process, namely rough throwing of copper, soft landing, and polishing of the barrier layer. The polishing of the barrier layer is a very critical step, because its purpose is to remove the barrier layer, clean all metal residues and organic residues on the surface, and stop at the thickness required by the process to form a copper interconnect. This step determines the final Surface topography, reliability and electrical properties. With the development of 45nm technology and the application of new materials, especially low dielectric materials, the key factors include surface contaminant particles, butterfly depression, thickness distribution, polishing uniformity, surface cleanliness and removal rate of low dielectric materials. The parameters have higher requirements. Especially in terms of surface contaminant control, electrical properties and reliability, its accuracy and range are getting smaller and more demanding, resistance values are distributed in different line widths, electromigration characteristics, breakdown voltage (VBD) distribution and time correlation. Dielectric breakdown (TDDB) and the like are all more dependent on the polishing of the barrier layer. Furthermore, the mechanical strength of low dielectric materials also requires a milder CMP process to protect the mechanical integrity of the dielectric layer. The cost control of polishing consumables also requires low cost of the polishing fluid and long life of the polishing pad, which are all for the barrier layer. Polishing presents a greater challenge. It can be said that there is no ideal and high quality barrier polishing, and further advancement of the technology node will not be possible. During the polishing process of the barrier layer, metal corrosion and dielectric material erosion, metal residue, organic material residue, polishing uniformity, etc. may occur. Because the manufacturing processes of the various wafer factories have different focuses, the barrier layer is flattened. There are also different requirements. In today's polishing liquid market, there is not a polishing solution that can solve all the problems, especially for the 45nm and below process, the thickness of the barrier layer is thinner, the package (cap) material and The physical properties of low dielectric materials make the formulation of the polishing solution more sensitive to changes in polishing performance, especially for the correction of surface defects, polishing uniformity and stability. The patent provides a barrier polishing liquid having a high removal rate of cerium oxide and an adjustable low dielectric material removal rate, low surface contaminants, no polishing residue of the polishing pad, and a strong surface. Defect repair capability. And the cost is low and easy to use.

The technical problem to be solved by the invention is to solve the problem that the removal of copper is sensitive to the change of hydrogen peroxide, the residual metal material on the polishing pad in the polishing process, and the removal rate of the low dielectric material. Solve the problem of correcting the surface defects on the graphic wafer.

The present invention provides a chemical mechanical polishing liquid comprising the following components: an abrasive, a metal corrosion inhibitor combination, a chelating agent, an oxidizing agent, and an organic solvent.

Among them, the abrasive is cerium oxide sol, gas phase cerium oxide. The particle size is from 20 to 200 nm, and most preferably from 30 to 120 nm. The abrasive content is 1-30%, preferably 5-20%

The metal corrosion inhibitor combination comprises an azole compound, a water soluble polymer, a macromolecular organophosphine or an organic phosphate. Wherein the azole compound is benzotriazole (BTA) and a derivative thereof, the water-soluble polymer is polyacrylic acid and a salt thereof or a polyacrylic acid copolymer, and the macromolecular organophosphine is a polyaminopolyether-based methylene Phosphonic acid (PAPEMP) or organic phosphate such as polyol phosphate (PAPE). The concentration of BTA ranges from 0.01 to 0.5%, preferably from 0.1 to 0.2%, and the concentration of the water-soluble polymer is from 0.01 to 1%, most preferably from 0.05 to 0.2%, of macromolecular organophosphine or organic phosphate. The content is in the range of 0.01% to 1%, preferably 0.05% to 0.5%.

The chelating agent is a monocarboxylic acid or a polycarboxylic acid, or an organic phosphine. For example, acetic acid, oxalic acid, malonic acid, citric acid, tartaric acid, succinic acid, adipic acid, etc., organic phosphine is 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), 2- Hydroxyphosphinic acid acetic acid (HPAA), hydroxyethylidene diphosphonic acid (HEDP), ethylenediaminetetramethylene phosphonate pentasodium (EDTMP), aminotrimethylene phosphonic acid (ATMP), etc., chelating agent addition amount It is 0.01-1%, and the most preferable is 0.1-0.5%.

Wherein, the organic solvent is an alcohol or ether organic solvent, preferably ethanol, propanol, ethylene glycol, propylene glycol, glycerol, diethylene glycol; ethylene glycol methyl ether, ethylene glycol ether, ethylene Alcohol butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dibutyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, Dipropylene glycol propyl ether and the like. The organic solvent is added in an amount of 0.1 to 10%, preferably 1 to 5%.

The above contents are all by mass percentage.

Among them, the oxidant is peroxide or persulfide, hydrogen peroxide, sodium peroxide, potassium peroxide, benzammonium peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, etc.

The chemical mechanical polishing liquid of the present invention further comprises: a bactericidal mold inhibitor such as a polyquaternium or the like.

The chemical mechanical polishing liquid of the present invention has a pH of 2 to 5, preferably 3-4.

In the present invention, the role of the abrasive is to remove the surface metal material and non-metal material that are reacted. The role of the chelating agent is to thoroughly understand the residual metal species on the polished surface. The role of the composite preservative is to protect the metal from corrosion, and in addition to the appropriate sensitivity to the oxidant, the metal in the protected recess is not quickly removed, thereby repairing the surface defects of the future. The role of the organic solvent is to change the adsorption performance of the polishing liquid on the wafer and the polishing pad, dissolve and remove organic residue and metal residue, prolong the life of the polishing pad, and improve polishing stability. And can improve the removal rate of cerium oxide and low-k materials to a certain extent, and inhibit the removal of copper, improve the diffusion behavior of the polishing liquid on the wafer and the polishing pad, and improve the polishing of different line width structures in the tube crystal (core). Uniformity.

The invention has the beneficial effects that the metal corrosion inhibitor combination is used to effectively protect the metal from corrosion during the polishing process, and can correct the surface defects of the front process to achieve the planarization effect, and the organic solvent is used to change the slurry and the polishing pad and The adsorption behavior between the wafers reduces the level of metal residues on the polishing pad, further improves the life of the polishing pad and increases the productivity. In addition, the organic solvent can also adjust the polishing selection ratio of different layers to a certain extent, which is more favorable to the process requirements. Thickness distribution and surface appearance.

Advantages of the present invention are further illustrated by the following detailed description.

Polishing conditions:

Polishing pad: Fujibo pad

Polishing conditions: 70/90 rpm

Polishing fluid flow rate: 100ml/min

Static Corrosion Rate: Freshly polished copper sheets were immersed in a slurry for 15 min, and the film thickness before and after measurement was measured.

Butterfly-shaped depression: The BD 854 graphic wafer covered with TEOS was used to measure the butterfly depression of the 80um metal block.

Polishing uniformity within the slice: a butterfly-shaped depression of different line widths within a tube (core).

From the above examples, we can see that the polishing liquid unique to this patent has more advantages than the comparative polishing liquid.

It can be seen from Fig. 1 that the metal corrosion inhibitor combination can adjust the removal rate of metallic copper with the sensitivity of hydrogen peroxide change to the range required by the process, that is, it cannot be so sensitive that the process is difficult to control and cannot be too inert, resulting in The thickness distribution is not adjustable.

As can be seen from Figures 2-4, the addition of an organic solvent changes the adsorption and diffusion properties of the polishing liquid on the wafer and the polishing pad. Thereby the removal rate of various film materials is changed. Further, the polishing uniformity in the tube crystal (core) is changed. The addition of organic solvent can improve the removal rate of dielectric materials including cerium oxide (PETEOS) and low dielectric material (BD1) to a certain extent, and reduce the removal of metallic copper, which can better improve surface defects and enable surface morphology. Meet the process requirements.

Using the unique combination of metal corrosion inhibitors of this patent, the sensitivity of the milder metal to the oxidant can be obtained, making the thickness control of the metal easier to control through the process parameters and the concentration of the oxidant. It is also possible to better correct the butterfly depression on the metal surface during the soft landing phase. The addition of organic solvent combined with the metal corrosion inhibitor combination greatly improves the uniformity of the slice level, so that the variation of the surface depression of different line widths in the same tube (core) is reduced to below 200 angstroms, and the performance is greatly improved. .

Figure 1 shows the change of copper removal rate with hydrogen peroxide concentration under different metal corrosion inhibitor combinations;

Figure 2 shows the removal rate of cerium oxide as a function of organic solvent concentration.

Figure 3 shows the polishing rate of a low dielectric material as a function of the amount of organic solvent added.

Figure 4 shows the change in metal removal rate with the amount of organic solvent added.

Claims (20)

A chemical mechanical polishing fluid for barrier layer planarization, comprising a) an abrasive; b) a metal corrosion inhibitor combination; c) a chelating agent; d) an organic solvent; e) an oxidizing agent; The ammonium salt composition, wherein the organic solvent is an ether organic solvent, and the ether organic solvent is selected from the group consisting of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether One or more of propylene glycol butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol diethyl ether and dipropylene glycol propyl ether, the metal corrosion The inhibitor combination comprises an azole compound, a water soluble polymer and a macromolecular organophosphine or organophosphate. The polishing liquid according to claim 1, wherein the abrasive is a cerium oxide sol. The polishing liquid according to claim 1, wherein the abrasive has a particle diameter of 20 to 200 nm. The polishing liquid according to claim 3, wherein the abrasive has a particle diameter of 30 to 120 nm. The polishing liquid according to claim 1, wherein the abrasive content is from 1 to 30% by weight. The polishing liquid according to claim 5, characterized in that the abrasive content is 5 to 20% by weight. The polishing liquid according to claim 1, wherein the azole compound is BTA and a derivative thereof, and the water-soluble polymer is a copolymer of polyacrylic acid and a salt thereof or acrylic acid, and the macromolecular organophosphine. Or the organophosphate is a polyamino polyether tetramethylene phosphonic acid or a polyol phosphate. The polishing liquid according to claim 1, wherein the concentration of the azole compound is 0.01 to 0.5% by weight, the concentration of the water-soluble polymer is 0.01 to 1% by weight, the macromolecular organic phosphine or organic phosphoric acid. The content of the ester is from 0.01% to 1% by weight. The polishing liquid according to claim 8, wherein the concentration of the azole compound is 0.1 to 0.2% by weight, the concentration of the water-soluble polymer is 0.05 to 0.2% by weight, the macromolecular organic phosphine or organic The content of the phosphate ester is from 0.05 to 0.5% by weight. The polishing liquid according to claim 1, wherein the chelating agent is an organic acid. The polishing liquid according to claim 10, wherein the organic acid is a mono- or polycarboxylic acid or an organic phosphine. The polishing liquid according to claim 11, wherein the mono- or polycarboxylic acid is one or more selected from the group consisting of oxalic acid, malonic acid, citric acid, tartaric acid, and succinic acid, and the organic phosphine is selected from the group consisting of PBTCA, One or more of HPAA, HEDP, EDTMP, and ATMP. The polishing liquid according to claim 1, wherein the chelating agent is added in an amount of from 0.01 to 1% by weight. The polishing liquid according to claim 13, characterized in that the chelating agent is added The addition amount is from 0.1 to 0.5% by weight. The polishing liquid according to claim 1, wherein the organic solvent is contained in an amount of from 0.1 to 10% by weight. The polishing liquid according to claim 15, wherein the organic solvent is contained in an amount of from 1 to 5% by weight. The polishing liquid according to claim 1, wherein the oxidizing agent is a peroxide and/or a persulfide. The polishing liquid according to claim 17, wherein the oxidizing agent is selected from the group consisting of hydrogen peroxide, sodium peroxide, potassium peroxide, benzammonium peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate. Or a variety. The polishing liquid according to claim 1, wherein the polishing liquid has a pH of 2 to 5. The polishing liquid according to claim 19, wherein the polishing liquid has a pH of 3-4.