Patent Description:
Copper is the current material of choice for the interconnect metal used in the fabrication of integrated electronic devices due to its low resistivity, high reliability, and scalability. Copper chemical mechanical planarization (Cu CMP) processes are necessary to remove copper overburden from inlaid trench structures while achieving global planarization with low metal loss.

With advancing technology nodes, the need to reduce metal dishing and metal loss is becoming increasingly important. Any new polishing formulations must also maintain high removal rates, high selectivity to the barrier material and low defectivity.

Copper CMP is known from the prior art, for example, in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; US <CIT>, <CIT>, and <CIT>.

However, the formulations disclosed in the prior art are unable to meet the performance requirements of high removal rates and low dishing which become more and more challenging for advanced technology nodes.

This invention discloses bulk copper CMP polishing formulations developed to meet challenging requirements of low dishing and high removal rates for advanced technology nodes.

Described herein are CMP polishing compositions, methods and systems for copper or Through Silica Via (TSV) CMP applications.

In a first aspect, the present invention provides a copper chemical mechanical polishing (CMP) composition, such as a copper bulk CMP or Through Silica Via (TSV) composition, comprising:.

In another aspect, the invention provides a method of chemical mechanical polishing a semiconductor substrate having at least one surface comprising copper or a copper-containing material and at least one second material, using a chemical mechanical polishing composition according to the first aspect comprising steps of:.

In yet another aspect, the present invention provides a system for chemical mechanical polishing a semiconductor substrate having at least one surface comprising copper or copper-containing material and at least one second material, the system comprising.

wherein at least a portion of the at least one surface is in contact with both the polishing pad and the chemical mechanical polishing composition.

The abrasive is selected from the group consisting of colloidal silica or high purity colloidal silica; colloidal silica particles doped with one or more metal oxides within the lattice of the colloidal silica, such as for example alumina doped silica particles; colloidal aluminum oxide; colloidal and photoactive titanium dioxide, cerium oxide, colloidal cerium oxide, nano-sized inorganic metal oxide particles, such as for example alumina, titania, zirconia, ceria etc.; nano-sized diamond particles, nano-sized silicon nitride particles; mono-modal, bi-modal, multi-modal colloidal abrasive particles; organic polymer-based soft abrasives, surface-coated or modified abrasives; composite particles; and combinations thereof. The colloidal aluminum oxide may for example comprise one or more of alpha-, beta- or gamma-types of aluminum oxides.

The organic quaternary ammonium salt is a choline salt, such as a choline bicarbonate salt, or any other salts formed between choline and other anionic counter ions.

The corrosion inhibitor is selected from the group consisting of <NUM>,<NUM>,<NUM>-triazole, benzotriazole and benzotriazole derivatives, tetrazole and tetrazole derivatives, imidazole and imidazole derivatives, benzimidazole and benzimidazole derivatives, pyrazole and pyrazole derivatives, and combinations thereof.

The biocide includes but is not limited to Kathon™ or Kathon™ CG/ICP II from Dow Chemical Co. These biocides have active ingredients of <NUM>-chloro-<NUM>-methyl-<NUM>-isothiazolin-<NUM>-one and <NUM>-methyl-<NUM>-isothiazolin-<NUM>-one.

The oxidizing agent includes, but is not limited to, periodic acid, hydrogen peroxide, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, and mixtures thereof.

The amino acids and amino acid derivatives are selected from the group consisting of glycine, D-alanine, L-alanine, DL-alanine, beta-alanine, valine, leucine, isoleuecine, phenylamine, proline, serine, threonine, tyrosine, glutamine, asparanine, glutamic acid, aspartic acid, tryptophan, histidine, arginine, lysine, methionine, cysteine, iminodiacetic acid, and combinations thereof.

As industry standards trend toward smaller device features, there is a continuously developing need for new Cu bulk metal polishing slurries that afford high and tunable Cu removal rates and low Cu dishing for broad and advanced node applications.

The copper bulk CMP or Through Silica Via (TSV) polishing compositions described herein satisfy the need for high and tunable Cu film removal rates, for high selectivity between copper and dielectric films, for high selectivity between copper and barrier films, for low and more uniform Cu line dishing across various wide Cu line features, and for better Cu film corrosion protection through using the suitable corrosion inhibitors.

The Cu CMP polishing compositions of the present invention comprise tris chelators, i.e. three chelating agents, an organic quaternary ammonium salt as an additional Cu dishing and defect reducer, a Cu corrosion inhibitor for efficient Cu corrosion protection, an abrasive such as nano-sized high purity colloidal silica, an oxidizing agent such as hydrogen peroxide, and water as a solvent.

The Cu CMP polishing compositions provide high and tunable Cu removal rates, and low barrier film and dielectric film removal rates which provide very high and desirable selectivity for Cu film vs. other barrier films, such as Ta, TaN, Ti, and TiN, and dielectric films, such as TEOS, low-k, and ultra low-k films, and low Cu dishing and more uniform Cu dishing across wide Cu line features.

The Cu chemical mechanical polishing compositions of the present invention also provide no pad stain Cu CMP performances which allow extended polish pad life and also allow more stable end-point detections.

The abrasive particles used for the Cu bulk CMP polishing compositions of the present invention are selected from the following: colloidal silica or high purity colloidal silica; colloidal silica particles doped with one or more metal oxides within the lattice of the colloidal silica, such as for example alumina doped silica particles; colloidal aluminum oxide; colloidal and photoactive titanium dioxide; cerium oxide, colloidal cerium oxide, nano-sized inorganic metal oxide particles, such as for example alumina, titania, zirconia, ceria etc.; nano-sized diamond particles; nano-sized silicon nitride particles; mono-modal, bi-modal, multi-modal colloidal abrasive particles; organic polymer-based soft abrasives; surface-coated or modified abrasives; composite particles; and mixtures thereof. The colloidal aluminum oxide may comprise one or more of alpha-, beta- or gamma-type aluminum oxides.

The colloidal silica can be made from silicate salts, and the high purity colloidal silica can be made from TEOS or TMOS. The colloidal silica or high purity colloidal silica can have narrow or broad particle size distributions with mono-model or multi-models, various sizes and various shapes including spherical shape, cocoon shape, aggregate shape and other shapes.

The nano-sized particles can also have different shapes, such as spherical, cocoon, aggregate, and others.

The Cu bulk CMP polishing compositions of the present invention comprise <NUM> wt. % to <NUM> wt. % abrasive, preferably <NUM> wt. % to <NUM> wt. %; preferably from <NUM> wt. % to <NUM> wt. %, and most preferably from <NUM> wt. % to <NUM> wt.

The choline salts can have the general molecular structure shown below:
<CHM>
wherein the anion Y- can be a bicarbonate, a hydroxide, a p-toluene-sulfonate, a bitartrate, or any other suitable anionic counter ion.

The CMP slurry of the present invention comprises from <NUM> wt. % to <NUM> wt. % organic quaternary ammonium salt, preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

Various per-oxy inorganic or organic oxidizing agents or other types of oxidizing agents can be used to oxidize the metallic copper film to the mixture of copper oxides to allow their quick reactions with chelating agents and corrosion inhibitors. The oxidizing agent includes, but is not limited to, periodic acid, hydrogen peroxide, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, and mixtures thereof. The preferred oxidizer is hydrogen peroxide.

The CMP slurry of the present invention comprises from <NUM> wt. % to <NUM> wt. % oxidizing agents; preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

The corrosion inhibitors used for the copper bulk CMP slurry of the present invention are selected from <NUM>,<NUM>,<NUM>-triazole, benzotriazole and benzotriazole derivatives, tetrazole and tetrazole derivatives, imidazole and imidazole derivatives, benzimidazole and benzimidazole derivatives, and pyrazole and pyrazole derivatives.

The CMP slurry comprises from <NUM> wt. % to <NUM> wt. % corrosion inhibitor; preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

A biocide having active ingredients for providing more stable shelf time of the invented Cu chemical mechanical polishing compositions can be used.

The biocide includes but is not limited to Kathon™ or Kathon™ CG/ICP II, from Dow Chemical Co. These biocides have active ingredients of <NUM>-chloro-<NUM>-methyl-<NUM>-isothiazolin-<NUM>-one and <NUM>-methyl-<NUM>-isothiazolin-<NUM>-one.

The CMP slurry comprises <NUM> wt. % to <NUM> wt. % biocide; preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

Optionally, acidic or basic compounds or pH adjusting agents can be used to allow the pH of the Cu bulk CMP polishing compositions to be adjusted to the optimized pH value.

The pH adjusting agents include, but are not limited to the following: nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, other inorganic or organic acids, and mixtures thereof. The pH adjusting agents also include basic pH adjusting agents such as sodium hydride, potassium hydroxide, ammonium hydroxide, tetraalkyl ammonium hydroxide, organic amines, and other chemical reagents that can be used to adjust the pH towards the more alkaline direction.

The CMP slurry of the present invention comprises from <NUM> wt. % to <NUM> wt. % pH adjusting agent; preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

The pH of the Cu CMP polishing compositions of the present invention is in the range of from <NUM> to <NUM>; preferably in the range of from <NUM> to <NUM>; and most preferably in the range of from <NUM> to <NUM>.

The CMP slurry of the present invention comprises from <NUM> wt. % to <NUM> wt. % in total of three chelators or chelating agents (i.e. tris chelators); preferably from <NUM> wt. % to <NUM> wt. %; and most preferably from <NUM> wt. % to <NUM> wt.

The first of the tris chelators is an organic amine selected from the group consisting of ethylenediamine, propylenediamine, and butylenediamine; and the second and third chelators are two different amino acids, two different amino acid derivatives, or combinations of one amino acid with one amino acid derivative. As a specific example, the tris chelators (three chelators) can be glycine, alanine and ethylenediamine.

The three chelators are used as complexing agents to maximize their reactions with the oxidized Cu film surfaces to form softer Cu-chelator layers to be quickly removed during Cu CMP process thus achieving high and tunable Cu removal rates and low copper dishing for broad or advanced node copper or TSV (Through Silica Via) CMP applications.

The amino acids and amino acid derivatives are selected from glycine, D-alanine, L-alanine, DL-alanine, beta-alanine, valine, leucine, isoleuecine, phenylamine, proline, serine, threonine, tyrosine, glutamine, asparanine, glutamic acid, aspartic acid, tryptophan, histidine, arginine, lysine, methionine, cysteine, iminodiacetic acid, and combinations thereof.

The associated methods of the present invention use the aforementioned compositions for chemical mechanical planarization of substrates comprising copper. In the methods of the present invention, a substrate (e.g., a wafer with Cu surface or Cu plug) can be placed face-down on a polishing pad which is fixedly attached to a rotatable platen of a CMP polisher. In this manner, the substrate to be polished and planarized is placed in direct contact with the polishing pad. A wafer carrier system or polishing head can be used to hold the substrate in place and to apply a downward pressure against the backside of the substrate during CMP processing while the platen and the substrate are rotated. The polishing composition (slurry) is applied (usually continuously) on the pad during CMP processing to effect the removal of material to planarize the substrate.

The polishing composition and associated methods of the present invention are effective for CMP of a wide variety of substrates and are particularly use for polishing copper substrates.

Polishing Pad Polishing pad, IC1010 pad or Other polishing pad was used during Cu CMP, supplied by Dow Chemicals Company.

All percentages are weight percentages unless otherwise indicated. In the examples presented below, CMP experiments were run using the procedures and experimental conditions given below. The CMP tool that was used in the examples was a <NUM> LK® polisher, or a Mirra® polisher, manufactured by Applied Materials, <NUM> Boweres Avenue, Santa Clara, California, <NUM>. An IC1010 pad or other type of polishing pad, supplied by Dow Chemicals Company was used on the platen for the blanket wafer polishing studies. Pads were broken-in by polishing twenty-five dummy oxide (deposited by plasma enhanced CVD from a TEOS precursor, PETEOS) wafers. In order to qualify the tool settings and the pad break-in, two PETEOS monitors were polished with Syton® OX-K colloidal silica, supplied by Planarization Platform of Air Products Chemicals Inc. at baseline conditions. Polishing experiments were conducted using blanket Cu wafers with <NUM> Angstroms in thickness, Ta and TEOS blanket wafers. These blanket wafers were purchased from Silicon Valley Microelectronics, <NUM> Campbell Ave, CA, <NUM>.

In the following working examples, the Cu slurry composition with a single chelator (not in accordance with the present invention) comprised <NUM> wt. % of glycine, <NUM> wt. % of <NUM>,<NUM>,<NUM>-triazole, <NUM> wt. % of high purity colloidal silica, and <NUM> wt. % of biocide. The Cu slurry# <NUM> composition with dual chelators (two chelators) (not in accordance with the present invention) comprised <NUM> wt. % of glycine, <NUM> wt. % of alanine, <NUM> wt. % of <NUM>,<NUM>,<NUM>-triazole, <NUM> wt. % of high purity colloidal silica, and <NUM> wt. % of biocide. The Cu slurry# <NUM> composition with tris chelators (three chelators) (in accordance with the present invention) comprised <NUM> wt. % of glycine, <NUM> wt. % of alanine, <NUM> wt. % of ethylenediamine, <NUM> wt. % of choline bicarbonate, <NUM> wt. % of <NUM>,<NUM>,<NUM>-triazole, <NUM> wt. % of high purity colloidal silica, and <NUM> wt. % of biocide.

All three of the above compositions used <NUM> wt. % of H<NUM>O<NUM> as oxidizing agent at point of use. The CMP polishing compositions had a pH ranging from <NUM> to <NUM>.

The polishing results from using the Cu bulk CMP polishing compositions are listed in Table <NUM> and depicted in <FIG>.

The single chelator was glycine, the dual chelators were glycine and alanine (alanine includes DL-Alanine; D-Alanine; and L-Alanine), and the tris chelators were glycine, alanine and ethylenediamine. In the tris chelator based polishing composition, an organic quaternary ammonium salt, choline bicarbonate, was also used.

The Cu CMP polishing compositions described herein afforded high and compatible Cu film removal rates when using tris chelator based Cu CMP polishing compositions.

The dual chelator based Cu slurry provided a <NUM>% higher Cu removal rate at <NUM> psi (<NUM> kPa) DF than the single chelator based Cu slurry, and a <NUM>% higher Cu removal rate at <NUM> psi (<NUM> kPa) DF than the single chelator based Cu slurry.

The tris chelator based Cu slurry provided a <NUM>% higher Cu removal rate at <NUM> psi (<NUM> kPa) DF than the single chelator based Cu slurry, and a <NUM>% higher Cu removal rate at <NUM> psi (<NUM> kPa) DF than the single chelator based Cu slurry.

Also, the tris chelator based Cu slurry provided a <NUM>% higher Cu removal rate at a <NUM> psi (<NUM> kPa) DF than the dual chelator based Cu slurry.

The <NUM>% increase in the Cu removal rate at <NUM> psi (<NUM> kPa) DF mainly resulted from the use of a third chelator, ethylenediamine, which is a binary chelating agent and reacts very effectively with Cu oxides to form water soluble Cu-etheylenediamine complexes and is subsequently removed during the Cu CMP process.

The polishing effects of the tris chelator based Cu CMP polishing compositions with/or without choline bicarbonate as an additional additive, and the single chelator based Cu polishing compositions on wide Cu line feature dishing are shown in Table <NUM>, and depicted in <FIG> and <FIG>.

As the wide Cu line dishing data showed in Table <NUM>, the Cu slurry with tris chelators, glycine/alanine/ethylenediamine provided a much lower Cu dishing on wide Cu line features than the Cu slurry only using single chelator, glycine.

On a 50x50µM Cu line feature, the averaged Cu dishing of the tris chelator based Cu slurry was reduced by <NUM>% when compared to the Cu slurry only using a single chelator, glycine. On a 10x10µM Cu line feature, the averaged Cu dishing of the tris chelator based Cu slurry was reduced by <NUM>% when compared to the Cu slurry only using a single chelator, glycine. And on a 9x1µM Cu line feature, the averaged Cu dishing of the tris chelator based Cu slurry was reduced by <NUM>% when compared to the Cu slurry using only a single chelator, glycine.

Further, the use of a choline bicarbonate salt in the tris chelator based Cu slurry also led to Cu line dishing reductions on 50x50µM and 10x10µM features. The Cu line dishing were reduced by about <NUM>% and <NUM>% respectively on the 50x50µM and 10x10µM features with the use of a choline bicarbonate salt in a glycine/alanine/ethylenediamie based tris chelator Cu slurry.

Also, the tris chelator based Cu slurry or the tris chelator based Cu slurry with choline bicarbonate afforded more uniform Cu line dishing across the three wide Cu line features. The delta of the Cu line dishing for the 50x50µM, 10x10µM and 9x1µM Cu line features was 511Å for the Cu slurry using glycine as single chelator, <NUM>Å for the Cu slurry using glycine/alanine/ethylenediamine as tris chelators, and 232Å for a Cu slurry using glycine/alanine/ethylenediamine as tris chelators plus choline bicarbonate as an additional additive to further reduce the Cu line dishing on some sized Cu line features.

The tris chelator based Cu slurry or tris chelator based Cu slurry with choline bicarbonate salt also reduced the Cu defect counts significantly compared to the single chelator based Cu slurry. 2micron Cu defect count results at <NUM>. 5psi (<NUM> kPa) DF are listed in Table <NUM>.

As the Cu defect count data shows in Table <NUM> and depicted in <FIG>, the Cu defect count was reduced by <NUM>% for the glycine/alanine/ethylenediamine based tris chelator Cu slurry when compared to the glycine based single chelator Cu slurry. The Cu defect count was reduced by <NUM>% for the glycine/alanine/ethylenediamine based tris chelator + choline bicarbonate Cu slurry when compared to the glycine based single chelator Cu slurry. In other words, Cu defect counts were reduced by <NUM>. 2X to 3X in tris chelator or tris chelator plus choline bicarbonate based Cu slurries when compared to the single chelator based Cu slurry.

The use of choline bicarbonate as an additional additive in the tris chelator based Cu slurry not only reduced Cu dishing on some wide Cu line features, but also further reduced Cu defect count by <NUM>% when compared to the tris chelators based Cu slurry.

The tris chelator based Cu CMP slurry or tris chelators with choline salt based Cu slurry showed very high selectivity toward barrier films or dielectric films. For example, greater than <NUM>:<NUM> of Cu: Ta selectivity was obtained for the tris chelator based Cu CMP slurry or tris chelator plus choline salt based Cu slurry.

Claim 1:
A copper chemical mechanical polishing (CMP) composition comprising:
a) <NUM> wt.% to <NUM> wt.% abrasive selected from the group consisting of colloidal silica or high purity colloidal silica; colloidal silica particles doped with one or more metal oxides within the lattice of the colloidal silica; colloidal aluminum oxide; colloidal and photoactive titanium dioxide; cerium oxide; colloidal cerium oxide; nano-sized inorganic metal oxide particles; nano-sized diamond particles; nano-sized silicon nitride particles; mono-modal, bi-modal, multi-modal colloidal abrasive particles; organic polymer-based soft abrasive; surface-coated or modified abrasive; composite particles; and combinations thereof;
b) <NUM> wt. % to <NUM> wt. % tris chelators wherein the first tris chelator is an organic amine selected from the group consisting of ethylenediamine, propylenediamine, and butylenediamine; and wherein the second and third chelators are two different amino acids, two different amino acid derivatives, or combinations of one amino acid with one amino acid derivative;
c) <NUM> wt.% to <NUM> wt.% corrosion inhibitor selected from the group consisting of <NUM>,<NUM>,<NUM>-triazole, benzotriazole and benzotriazole derivatives, tetrazole and tetrazole derivatives, imidazole and imidazole derivatives, benzimidazole and benzimidazole derivatives, pyrazole and pyrazole derivatives, and combinations thereof;
d) <NUM> wt.% to <NUM> wt.% organic quaternary ammonium salt which is a choline salt formed between choline and other anionic counter ions;
e) <NUM> wt.% to <NUM> wt.% oxidizing agent;
f) <NUM> wt.% to <NUM> wt.% biocide;
g) <NUM> wt.% to <NUM> wt.% pH adjusting agent; and
h) water;
wherein the composition has a pH in the range of from <NUM> to <NUM>;
wherein
the amino acid or the amino acid derivative is selected from the group consisting of glycine, D-alanine, L-alanine, DL-alanine, beta-alanine, valine, leucine, isoleucine, phenylamine, proline, serine, threonine, tyrosine, glutamine, asparanine, glutamic acid, aspartic acid, tryptophan, histidine, arginine, lysine, methionine, cysteine, iminodiacetic acid, and combinations thereof.