TWI635168B - Chemical mechanical polishing slurry - Google Patents

Abstract

A chemical mechanical polishing slurry for copper contains at least one phosphate surfactant, and further contains abrasive particles, a complexing agent, and an oxidizing agent. The use of the slurry of the present invention can reduce the static corrosion rate of copper, suppress the removal rate of copper at low pressure, and reduce dishing after polishing.

Description

Chemical mechanical polishing slurry

The present invention relates to a chemical mechanical polishing slurry for copper.

With the development of microelectronics technology, the integration of very large integrated circuit chips has reached several billion components, and the feature size has entered the nanometer (n) grade, which requires hundreds of processes in the microelectronics process, especially Multilayer wiring, substrate, and dielectric must be chemically mechanically planarized. Very large scale integrated wiring is being converted from conventional Al to Cu. Compared with Al, Cu wiring has low resistivity, high electromigration resistance, and short RC delay time. The advantages of Cu wiring have made it a substitute for Al as a interconnect metal in semiconductor fabrication. However, there is currently no known technique for effective plasma (or plasma) etching or wet etching of copper to form a copper interconnect in an integrated circuit. Therefore, the chemical mechanical polishing method of copper is considered to be the most An effective process.

The chemical mechanical polishing process of copper is generally divided into three steps. The first step is to remove a large amount of copper on the surface of the substrate with a high and low pressure at a high and low removal rate. The second step is to approach the barrier layer. When the downforce is lowered, the removal rate is reduced to polish the remaining metal copper and stopped in the barrier layer. In the third step, the barrier layer polishing solution is used to remove the barrier layer and part of the dielectric layer and the metal copper to achieve planarization. Copper chemical mechanical polishing fluids are used in both steps 1 and 2.

On the one hand, copper polishing should remove excess copper on the barrier layer as soon as possible, and on the other hand, minimize the dishing of the polished copper wire. The copper wire is partially recessed before the copper is polished. During polishing, the copper on the dielectric material is easily removed (higher) at the bulk pressure, while the copper at the depression is subjected to a lower polishing pressure than the bulk pressure, and the copper removal rate is small. As the polishing progresses, the height difference of the copper is gradually reduced to achieve flattening. However, in the polishing process, if the chemical action of the copper polishing solution is too strong and the static etching rate is too high, the passivation film of copper is easily removed even under a lower pressure (such as a copper line depression), resulting in lowering of planarization efficiency. The polished dishing is enlarged.

At present, there is a series of chemical mechanical polishing slurries suitable for polishing Cu, such as: US Pat. No. 6,616,717, the disclosure of which is incorporated herein incorporated by reference. Chemical mechanical polishing slurry; Patent No. US 6,821,897 discloses a copper CMP method using a polymer complexing agent; Patent No. CN 02114147.9 discloses a copper chemical-mechanical polishing process polishing liquid; Patent No. CN 01818940.7 A slurry for chemical mechanical polishing of copper; Patent No. CN 98120987.4 discloses a CMP slurry for copper and a method for manufacturing an integrated circuit. However, the above-mentioned polishing slurry for copper has a polishing speed which is not fast enough, and there are defects, scratches, stains, and residual copper on the surface of the substrate after use, or the depression of the copper block after polishing is too large, or there is a local part in the polishing process. Or overall corrosion and high static corrosion rate of copper at normal temperature and polishing temperature (such as 50 ° C). Therefore, it is necessary to develop a new chemical mechanical polishing slurry for copper.

It is an object of the present invention to overcome the deficiencies of the prior art and to provide a chemical mechanical polishing slurry for copper. The polishing slurry contains at least one phosphate surfactant, which further contains abrasive particles, a complexing agent, and an oxidizing agent. The use of the slurry of the present invention can reduce the static corrosion rate of copper, suppress the removal rate of copper at low pressure, and reduce the dishing of the copper block after polishing.

Specifically, a specific method of the present invention is to add a phosphate surfactant to the polishing slurry, and the phosphate surfactant has the following structure:

(X=RO, RO-(CH ₂ CH ₂ O) _n , RCOO-(CH ₂ CH ₂ O) _n ) or a polyol phosphate containing two or more structural formulas 1.

Wherein R is an alkyl or alkylbenzene of C8 to C22, a glyceryl group (C ₃ H ₅ O ₃ -), etc.; n = 3 to 30, M = H, K, NH ₄ , (CH ₂ CH ₂ O) _{1 ~3} NH _3~1 and / or Na.

The content of the phosphate surfactant described in the present invention is 0.0005 to 2% by weight, preferably 0.001 to 1% by weight.

The abrasive particles described in the present invention include ceria, alumina, doped aluminum or aluminum-coated ceria, ceria, titania and/or polymer abrasive particles. The weight percentage of the abrasive particles is preferably from 0.1 to 20%; more preferably from 0.1 to 10%. The abrasive particles have a particle size of 20 to 150 nm.

The complexing agent is an aminocarboxylate compound and a salt thereof, an organic carboxylic acid and a salt thereof, an organic phosphonic acid and a salt thereof, and an organic amine. The aminocarboxylate compound is specifically glycine, alanine, valine, leucine, valine, phenylalanine, tyrosine, tryptophan, lysine, arginine, histidine , serine, aspartic acid, glutamic acid, aspartame, glutamine, ammonia triacetic acid, ethylenediaminetetraacetic acid, cyclohexanetetraacetic acid, ethylenediamine disuccinic acid, diethylenetriamine One or more of acetic acid and triethylenetetramine hexaacetic acid; the organic carboxylic acid is acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, succinic acid, malic acid, lactic acid, gallic acid and sulfo group One or more of salicylic acid; the organic phosphonic acid is 2-phosphonic acid butane-1,2,4-tricarboxylic acid, aminotrimethylene phosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediamine four One or more of methylidenephosphonic acid, diethylenetriamine pentamethylphosphonic acid, 2-hydroxyphosphonic acid acetic acid, ethylenediaminetetramethylenephosphonic acid, and polyaminopolyether methylphosphonic acid; The organic amine is ethylenediamine, diethylenetriamine, pentamethyldiethylenetriamine, polyethenepolyamine, triethylenetetramine, tetraethylenepentamine, and the like. The salts are potassium, sodium and/or ammonium salts. The content of the complexing agent is 0.01 to 10% by mass.

The oxidizing agent is one of hydrogen peroxide, urea peroxide, peroxyformic acid, peracetic acid, persulfate, percarbonate, periodic acid, perchloric acid, perboric acid, potassium permanganate and ferric nitrate. Or a variety.

The content of the oxidizing agent is 0.05 to 10% by mass.

The polishing liquid of the present invention has a pH of from 3 to 11, preferably from 4 to 8.

The polishing liquid of the present invention may further contain other conventional additives in the art such as a corrosion inhibitor, a pH adjuster, a viscosity modifier, an antifoaming agent, and a bactericide to achieve a polishing effect.

The polishing liquid of the present invention can prepare a concentrated sample which is diluted with deionized water to the concentration range of the present invention and added with an oxidizing agent before use.

The positive progress of the present invention is that the polishing slurry of the present invention can significantly reduce the static etching rate of copper, suppress the removal rate of copper under low pressure, and reduce the dishing of the copper block after polishing of the pattern wafer.

The invention is further illustrated by the following examples, but the invention is not limited thereto.

Examples 1 to 47

Table 1 shows Examples 1 to 47 of the chemical mechanical polishing liquid of the present invention. According to the formulation given in the table, the components other than the oxidizing agent were uniformly mixed, and the mass percentage was made up to 100% with water. Adjust to the desired pH with KOH or HNO ₃ . Add oxidizing agent before use and mix well.

Effect Example 1

Table 2 gives a comparison of the static corrosion rates of the comparative polishing slurries 1 to 5 and the polishing slurry examples 48 to 58 of the present invention and copper. According to the formulation given in the table, the components other than the oxidizing agent are mixed. uniform, the percentage made up with water to 100% by mass, adjusted with HNO ₃ or KOH to a pH desired. Add oxidizing agent before use and mix well.

The empty copper (Cu) was placed in the comparative polishing slurry 1 to 5 and the polishing slurry examples 48 to 58 of the present invention, and the immersion time was 30 minutes. The difference in thickness of the copper before and after the immersion was measured to obtain the static corrosion rate. 2.

As can be seen from Table 2, in comparison with Comparative Examples 1 to 5 in which no phosphate ester surfactant was added, the addition of at least one phosphate ester surfactant to Examples 48 to 58 can preferably suppress the static corrosion rate of copper. Helps reduce the removal rate of copper at low pressure and contributes to the improvement of planarization efficiency.

Effect Example 2

The copper (Cu) wafer and the patterned copper wafer are polished using the comparative polishing liquid 1 and the polishing liquid 50, 51 of the present invention. The polishing rate of the obtained copper is shown in Fig. 1. The polishing conditions of the pattern wafer and the dishing value of the copper block are shown in Table 3.

Empty sheet polishing conditions: copper wafer: down-pressure 1~3 psi; polishing disc and polishing head rotation speed 93/87 rpm, polishing pad IC1010, polishing liquid flow rate 150 ml/min, polishing machine stage 8" Mirra.

Patterned copper wafer polishing process conditions: polishing disc and polishing head rotation speed 93/87 rpm, polishing pad IC1010, polishing liquid flow rate 150 ml/min, polishing machine table 8" Mirra. Polished on the polishing disc 1 with corresponding downforce The patterned copper wafer was left to residual copper of about 3000 A, and then the residual copper was removed and polished for 20 seconds on the polishing disk 2 with a corresponding downforce. The patterned copper wafer was measured by XE-300P atomic force microscope at 80 um*80 um. The dishing value of the copper block.

It can be seen from Fig. 1 and Table 3 that phosphate ester surfactants are added to Examples 50 and 51 as compared with Example 1 without the addition of phosphate ester surfactant, which can inhibit copper under low pressure. The removal rate is beneficial to reduce dishing on the patterned copper wafer, while maintaining a high copper removal rate under high pressure and increasing throughput.

Claims (9)

The invention relates to a chemical mechanical polishing slurry used for polishing copper, characterized in that the chemical mechanical polishing liquid is composed of a phosphate surfactant, abrasive particles, a complexing agent and an oxidizing agent, wherein the phosphate ester surface active The agent has the following structure: or X=RO, RO-(CH ₂ CH ₂ O) _n , RCOO-(CH ₂ CH ₂ O) _n or a polyol phosphate containing two or more structural formula 1, wherein R is a C8-C22 alkyl or alkane Base benzene, triol (C ₃ H ₅ O ₃ -); n=3~30, M=H, K, NH ₄ , (CH ₂ CH ₂ O) _1~3 NH _3~1 and/or Na; The content of the phosphate surfactant described therein is 0.002 to 0.2% by weight. The application of claim 1, wherein the abrasive particles are ceria, alumina, doped aluminum or aluminum-coated ceria, ceria, titania and/or polymeric abrasive particles. The application of claim 1, wherein the abrasive particles have a concentration by weight of 0.1 to 20%. The application according to claim 1 or 2, wherein the abrasive particles have a particle diameter of 20 to 150 nm. The application according to claim 1, wherein the complexing agent is an aminocarboxylate compound and a salt thereof, an organic carboxylic acid and a salt thereof, an organic phosphonic acid and a salt thereof, and/or an organic amine. The application according to claim 5, wherein the aminocarboxy compound is selected from the group consisting of glycine, alanine, valine, leucine, valine, phenylalanine, tyrosine, and color ammonia. Acid, lysine, arginine, histidine, serine, aspartic acid, threonine, glutamic acid, aspartame, One or more of glutamine, ammonia triacetic acid, ethylenediaminetetraacetic acid, cyclohexanetetraacetic acid, ethylenediamine disuccinic acid, diethylenetriaminepentaacetic acid, and triethylenetetramine hexaacetic acid; The organic carboxylic acid is one or more of acetic acid, oxalic acid, citric acid, tartaric acid, malonic acid, succinic acid, malic acid, lactic acid, gallic acid and sulfosalicylic acid; the organic phosphonic acid is 2 - phosphonic acid butane-1,2,4-tricarboxylic acid, aminotrimethylene phosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylene phosphonic acid, diethylenetriamine pentamethylphosphonic acid, 2- One or more of hydroxyphosphonic acid acetic acid, ethylenediaminetetramethylene phosphonic acid, and polyaminopolyether methylphosphonic acid; the organic amine is ethylenediamine, diethylenetriamine, pentamethyldiethylene Triamine, polyethene polyamine, triethylenetetramine, tetraethylenepentamine; the salts are potassium, sodium and/or ammonium salts. The application according to claim 1, characterized in that the content of the complexing agent is 0.01 to 10% by mass. The application of claim 1, wherein the oxidizing agent is selected from the group consisting of hydrogen peroxide, urea peroxide, peroxyformic acid, peracetic acid, persulfate, percarbonate, periodic acid, perchloric acid. One or more of perboric acid, potassium permanganate and ferric nitrate. The application according to claim 1, wherein the oxidizing agent is contained in an amount of 0.05 to 10% by mass.