CN101928520B - Abrasive composition for planarizing metal layers - Google Patents

Abstract

The present invention discloses a polishing composition for planarizing a metal layer. The polishing composition comprises at least about 750ppm to less than 5000ppm by weight of abrasive grains, hydrogen peroxide, an accelerator, a common corrosion inhibitor and water. The common corrosion inhibitor comprises a first corrosion inhibitor and a second corrosion inhibitor. The common corrosion inhibitor is applied to the planarized metal layer. While maintaining a high polishing removal rate of the metal layer, it also has the characteristic of inhibiting metal etching, thereby reducing polishing defects such as dishing and erosion.

Description

Abrasive composition for planarizing metal layers

technical field

The invention relates to a polishing composition for flattening a metal layer, and aims to provide a polishing composition for chemical machinery, which can improve the flattening effect of the processed object.

Background technique

As the critical dimension (Critical Dimension) of electronic components becomes smaller and the number of wire layers increases rapidly, the resistance/capacitance time delay (RC Time Delay) will seriously affect the operation speed of the overall circuit. In order to improve the time delay and electromigration reliability problems caused by the narrowing of the metal connection line width, copper wire materials with low resistivity and high resistance to electromigration damage are selected to replace aluminum alloy metal. However, since copper metal is not easily etched, another damascene method must be used to form copper metal wires.

The Damascene process is different from the traditional metallization process that first defines the metal pattern and then fills the trench with the dielectric layer. The method is to etch the trench of the metal line on a flat dielectric, and then the metal layer filling, and finally removing excess metal to obtain a flat structure with metal embedded in the dielectric layer. Compared with the traditional metallization process, the damascene process has the following advantages: (1) It can keep the substrate surface flat at any time; (2) It can eliminate the disadvantage that the dielectric material is not easy to fill the gap between the metal wires in the traditional process: (3) It can solve the problem of metallization. The difficulty of layer material etching, especially the etching of copper metal.

In addition, in order to overcome the disadvantage that the contact window structure and the wire pattern need to be manufactured separately in the traditional inline machine process, making the entire process steps extremely complicated, a dual damascene process has been developed, and the manufacturing process is performed twice. Selective etching, after etching away the line dielectric and the via dielectric, the metal layer and the barrier layer of the plug are completed at one time, and the conductive metal is filled into the via layer at one time Window and in-line groove, to achieve the effect of simplifying the process steps. In recent years, in order to meet the development of component size reduction and the need to increase the operating speed of components, copper metal with low resistivity constant and high electron migration resistance has been gradually applied as the material of metal interconnectors, replacing the previous aluminum metal process. technology. The copper metal mosaic interconnection technology can not only achieve the miniaturization of the interconnection and reduce the RC time delay, but also solve the problem that metal copper is not easy to etch, so it has become the main development trend of multiple interconnections today.

Regardless of the single damascene or dual damascene copper process, a planarization process is required after the copper metal filling is completed to remove excess metal on the dielectric layer. Currently, this goal is usually achieved by a chemical mechanical polishing process. However, in metal chemical mechanical polishing technology, polishing defects such as metal dishing and erosion still often occur on the surface of the metal layer.

The phenomenon of metal dishing and abrasion has a great relationship with the grinding rate and etching ratio (RR/DER). A lower etching rate can ensure a low removal rate of patterned recesses, thereby effectively suppressing dishing defects, but considering the unit time The grinding rate also needs to be maintained in an acceptable range under the output of high output; in addition, the grinding uniformity also has a certain influence on the flat result, and the poor uniformity requires more grinding time to completely remove the copper, thus causing more Severe metal dishing and abrasion.

In order to take into account the unit output and suppress metal sinking and abrasion, the copper-chemical mechanical polishing process is usually divided into two steps. The first stage removes most of the copper at a faster grinding rate to increase yield per unit. In the second stage, the remaining small amount of copper is removed at a slower grinding rate, so as to avoid excessive abrasion of the copper in the groove. Generally, in the two-stage copper polishing process, it is necessary to replace the polishing composition with different compositions to meet the requirements of copper polishing in different stages. However, replacing the abrasive composition is not conducive to simplifying the manufacturing process, and may also increase waste.

The abrasive composition disclosed in U.S. Publication No. 2008/0254629 includes: amino acid, abrasive particles from about 5 ppm to less than 700 ppm by weight, triazole compound, and water. The removal selectivity exceeds 50:1; and the U.S. No. 2004/0020135 published patent document discloses a copper metal abrasive composition comprising silicon dioxide, oxidizing agent, amino acid, triazole compound, and water; moreover, U.S. Patent No. Patent No. 6,440,186 discloses an abrasive composition comprising: abrasive grains, a protective film forming agent and hydrogen peroxide, the abrasive grains have a particle size of 50-120 nm, and account for 0.5-5 wt% of the total weight of the abrasive composition % (wt%); In addition, U.S. Patent No. 6,679,929 discloses that a kind of abrasive composition comprises: abrasive particles, an aliphatic carboxylic acid with at least 10 carbons, an alkaline substance selected from ammonium hydroxide, etc. solvents, corrosion inhibitors, hydrogen peroxide, and water. However, the above-mentioned patents do not disclose that the use of a common inhibitor can slow down the etching rate of the abrasive composition on the metal under the condition of maintaining a high grinding removal rate, and is suitable for both the first and second stages of copper metal grinding.

Contents of the invention

The main purpose of the present invention is to provide an abrasive composition for planarizing metal layers, which can improve the planarization effect of the processed object.

Another object of the present invention is to provide a polishing composition suitable for two-stage metal polishing.

To achieve the above disclosure, the abrasive composition of the present invention at least includes abrasive grains, hydrogen peroxide, accelerators, common corrosion inhibitors and water from about 750 ppm to less than 5000 ppm by weight, wherein the common corrosion inhibitors include the first 1. The second corrosion inhibitor, the co-corrosion inhibitor applied to the planarized metal layer, can maintain the high grinding removal rate of the metal layer while having the characteristics of inhibiting metal etching, and can reduce grinding such as dishing and abrasion defect.

Description of drawings

Fig. 1 is the relationship diagram of abrasive particle concentration and grinding removal rate;

Fig. 2 is a linear performance diagram with a larger slope for abrasive particles with larger particle diameters;

Fig. 3 is a graph showing the results of the concentration of abrasive grains and metal dishing.

Detailed ways

The features of the present invention can be clearly understood by referring to the drawings and the detailed description of the embodiments.

The abrasive composition used for planarizing metal layers of the present invention, the abrasive composition at least includes: abrasive grains, hydrogen peroxide, accelerator, co-corrosion inhibitor and water from about 750ppm to less than 5000ppm by weight, wherein, the The common corrosion inhibitor includes the first and second corrosion inhibitors, and the common corrosion inhibitor is used in the planarization metal layer, which can form a protective film on the surface of the processing object during chemical mechanical polishing, so as to avoid the processing object Excessive corrosion can improve the corrosion inhibition ability of the processed object.

The weight of the abrasive grains is about 750ppm to less than 5000ppm, and preferably 1000ppm to less than 3000ppm, and the particle diameter of the abrasive grains is less than 90nm (wherein less than 50nm is preferred), and the examples of the abrasive grains Including, but not limited to, calcined silica; silica sol from hydrolysis of sodium or potassium silicate, or hydrolysis and condensation of silanes; precipitated or calcined alumina; precipitated or calcined titania ; polymer material; and metal oxide and polymer material mixture (hybrid). Silica sol is preferred. If the amount of abrasive grains is too low, it is not conducive to mechanical grinding, and the desired grinding removal rate cannot be achieved; on the other hand, if the amount of abrasive grains is too high, the effect of mechanical grinding will be accelerated, and the removal rate of barrier layer and insulating oxide layer will be increased. , It is also prone to grinding defects of surface abrasion.

The oxidizing agent accounts for 0.25 to 5% by weight of the total weight of the composition; and examples of accelerators for the grinding composition include, but are not limited to, citric acid, oxalic acid, tartaric acid, histidine, alanine, or glycine and Its ammonium, sodium, potassium or lithium salts. The accelerator is used to accelerate the dissolution of the metal to be ground, such as copper. Increasing the amount of accelerator added in the grinding composition helps to improve the grinding removal rate of the metal layer, and is suitable for the first stage of metal layer grinding. However, increasing the amount of accelerator added in the polishing composition will also increase the rate of static etching, which is not conducive to the fine grinding in the second stage. In one embodiment, the accelerator accounts for 0.01 to 5% by weight of the composition.

The common corrosion inhibitor can effectively suppress the static etching rate under the condition of high grinding removal rate, so as to be applicable to the polishing process of the first stage and the second stage. The first corrosion inhibitor of the present invention is selected from 1-H-benzene Triazole, N-acyl sarcosine (N-acyl sarcosine), alkyl sulfate (Alkyl sulfate) or alkyl sulfonate (Alkyl sulfonate), and the second corrosion inhibitor is selected from 1,2, 3-triazole, 1,2,4-triazole, totyltriazole, 5-amino tertraazole, 3-amino-1,2,4-triazole (3- Amino-1,2,4-triazole), 4-amino-4H-1,2,4,-triazole (4-Amino-4H-1,2,4-triazole), 3-nitro-1, 2,4-triazole (3-Nitro-1,2,4-triazole), 3-mercapto-1,2,4-triazole (3-Mercapto-1,2,4-triazole), 1H-1, 2,3-triazole-1-ethanol (1H-1,2,3TRIAZOLE-1-ETHANOL), benzimidazole (benzimidazole), imidazole (imidazole), pyrrole (Pyrrole), pyrroline (Pyrroline), oxazole ( Oxazole), isoxazole (Isoxazole), indazole (INDAZOLE) or indolizine (INDOLIZINE), and the common corrosion inhibitor accounts for 0.001 to 1% by weight of the total composition.

The features and functions of the present invention are further described below through specific specific examples, but they are not intended to limit the scope of the present invention.

Example 1-5

According to list in table 1, use the abrasive slurry composition that comprises silica sol abrasive grain, glycine, hydrogen peroxide, 1-H-benzotriazole (BTA), 1,2,4-triazole and water Implement samples for testing.

Table 1

The grinding test was performed under the following conditions.

Grinder: Mirra polisher (Applied Materials)

Wafer type: 8”, 15KA Copper blanket wafer (Ramco Co)

Grind Downforce: 3, 1.5 and 0psi

Platform speed: 93rpm

Vehicle speed: 87rpm

Polishing pad: IC1010 (Rohm Hass Electronic Materials)

Slurry flow rate: 150ml/min.

The wafer uses a 4-point probe to measure the thickness of the copper film before and after grinding to calculate the rate. The results are shown in Table 2:

Table 2

Among them, the RR refers to the grinding removal rate (Removal Rate), and DER refers to the dynamic etching rate (Dynamic etching rate), that is, the removal rate at 0psi.

According to the results in Table 2, the examples 1 and 2 can illustrate the effectiveness of common corrosion inhibitors, wherein Example 2 uses common corrosion inhibitors, and the results show that it has a higher RR/DER value, while in the common corrosion inhibitors The BTA is used for the function of rough adjustment in the grinding removal mechanism, and 1,2,4-triazole is used for the function of fine adjustment; while in Examples 4 and 5, the more accelerator content, the higher the grinding removal rate, However, the dynamic etching rate will also increase accordingly, and the inhibitor needs to be adjusted as a control. Therefore, the optimal polishing composition must strike a balance between the polishing removal rate and the RR/DER value.

Example 5-6

According to list in table 3, use the abrasive slurry composition that comprises silica sol, glycine, hydrogen peroxide, 1-H-benzotriazole (BTA), 1,2,4-triazole and water Implement samples for testing.

table 3

The grinding test was carried out according to the following conditions, and the results are recorded in Table 4.

Wafer type: MIT854patterned wafer (Ramco Co)

Grinding Downforce: 3psi

Platform speed: 93rpm

Vehicle speed: 87rpm

Slurry flow rate: 150ml/min.

Use the HRP220profiler (KLA-Tenco) instrument to measure the degree of metal disc sinking at each measurement point after grinding. During the measurement, a 100x100 micron copper wire is used as the measurement point, and the results of measuring the crystal grains at the center, middle and edge of the wafer are recorded in the table. 4:

Table 4

(Angstrom)。对于晶片制程而言，此乃是极具实用性的表面轮廓(Topographies)。本案所研发出来的组成物具优异的功效且经证实可供用作为晶片制程的CMP。These metal disc sinking values are 30% over-polished after the end point. According to the results in Table 4, these values are all lower than

(Angstrom). For the wafer process, this is a very practical surface profile (Topographies). The composition developed in this case has excellent efficacy and has been proven to be used as CMP in wafer process.

Example 7-13

As listed in Table 5, the test was performed using a control sample of abrasive composition comprising silica sol abrasive grains, glycine, hydrogen peroxide, benzotriazole, 1,2,4-triazole and water.

table 5

Each embodiment of table 5 is on the grinder platform of Mirra polisher (Applied Materials), and carries out grinding test according to the condition listed in embodiment 1-5, and the wafer of grinding has Cu, Ta and TaN Blanket wafers, and its The results are shown in Table 6 and Figure 1:

Table 6

According to the results in Table 6, it can be seen that the higher the abrasive particle concentration, the higher the copper grinding removal rate, and this phenomenon is more obvious when the abrasive particle size is larger; and when the abrasive particle concentration reaches a certain content, the grinding removal rate will decrease. When reaching a flat area, it will no longer rise, and the abrasive grains with larger particle size will reach the flat area faster than the abrasive grains with smaller particle size. This result shows that there is a limit to the enhancement of the removal rate achieved by the concentration of silica; there is no difference in this aspect whether the silica with small particle size or large particle size is used. Since the concentration of silicon dioxide has its limitation on the improvement of the removal rate, an appropriate and effective concentration range can be selected in the application.

Examples 8-11

According to the listing in Table 7, use Example 8 and Example 11 to carry out under different grinding pressures.

Table 7

Each embodiment of Table 7 was carried out on the grinding machine platform of Mirra polisher (Applied Materials), and according to the conditions listed in Examples 1-5, and wherein the grinding force (Df) was 1.5, 2 and 3 psi respectively for grinding test , and use a 4-point probe to measure, the results are shown in Table 8 and Figure 2:

Table 8

According to the results in Table 8, it can be seen that under the condition of 3psi under the grinding pressure, the abrasive grains with large particle size (87nm) have a higher copper grinding removal rate; Abrasive grains have a higher removal rate of copper grinding, and Figure 2 shows that the abrasive grains with larger diameters have a linear performance with a larger slope, that is, abrasive grains with larger diameters are more effective under high grinding pressure conditions; however , In the advanced Cu CMP process, there is a disadvantage under high downforce, that is, it will cause damage to low-k value materials and will generate defects. Therefore, most chemical mechanical polishing processes try to avoid using a grinding pressure greater than 2.5 psi, so it is necessary to limit the particle size of the abrasive grains to a smaller range in the chemical mechanical polishing process.

According to Table 7, the patterned wafer (type MIT854) was polished under the same parameter conditions by using Embodiment 8 and Embodiment 11. After the patterned wafer is the end point, it is over-polished by 30%. When measuring, the copper wire of 100x100 microns is used as the measurement point to measure the metal dish at the center, middle and edge of the wafer. The results are recorded in Table 9:

Table 9

The results show that although the abrasive grains with larger grain size can provide high grinding removal rate (shorter grinding time), but the subsequent grinding defects such as metal disc sinking are aggravated, so the abrasive grains with smaller grain size are chemically It is more favorable in the mechanical grinding process.

Examples 14-17

As listed in Table 10, samples were tested using an abrasive composition comprising silica sol abrasive grains, glycine, hydrogen peroxide, benzotriazole, 1,2,4-triazole and water.

Table 10

Each embodiment of Table 10 is ground in the grinding machine platform of Mirra polisher (Applied Materials) and blanket type copper wafer (Blanket Cu wafers) and patterned wafer (type is MIT854), wherein, the grinding removal rate and The results, such as the average value of the metal discs at the measurement points of the center, middle and edge grains of the wafer after grinding, are recorded in Table 11 and Figure 3:

Table 11

Silica sol (ppm) Cu RR3psi(A/min) The average value of the metal dish (A) Example 14 1000 6468 710 Example 15 5000 7312 1277 Example 16 10500 7659 1840 Example 17 5000 7307 1213

Table 11 reveals that the grinding removal rate increases slowly with the increase of the abrasive particle concentration, but this increase is very small. For example, comparing Examples 14 and 16, the grinding removal rate only increases by 18%, but it needs to be increased More than 10 times the concentration can be achieved. In Figure 3, it can be clearly seen that the concentration of abrasive grains does affect the result of metal dishing, that is, the more abrasive grains (the higher the concentration), the worse the abrasive defects such as metal dishing. In order to ensure that metal dishing is controlled to an acceptable level, the concentration of abrasive particles must be limited to a certain range.

The technical content and technical features of the present invention have been disclosed above, but those skilled in the art may still make various replacements and modifications based on the disclosure of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to those disclosed in the embodiments, but should include various replacements and modifications that do not depart from the present invention, and are covered by the scope of the following patent applications.

Claims (9)

1. at two-stage copper metallization, learn a grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in grinding processing procedure, this grinding composite is comprised of following composition:

Abrasive particle, the weighing scale 750ppm of this abrasive particle is extremely lower than 5000ppm;

Hydrogen peroxide;

Accelerator, be selected from citric acid, oxalic acid, tartrate, histidine, Beta Alanine, glycine with and cohort that ammonium salt, sodium salt, sylvite or lithium salts were formed;

Common corrosion inhibitor, this common corrosion inhibitor is by first, the second corrosion inhibitor forms, wherein this first corrosion inhibitor is selected from 1-H-benzotriazole, the acid of N-anilide musculamine, the cohort that alkyl-sulphate or alkylsulfonate form, and this second corrosion inhibitor is selected from 1, 2, 3-triazole, 1, 2, 4-triazole, tolytriazole, 5-amido tetrazolium, 3-amido-1, 2, 4-triazole, 4-amido-4H-1, 2, 4,-triazole, 3-nitro-1, 2, 4-triazole, 3-sulfydryl-1, 2, 4-triazole, 1H-1, 2, 3-triazole-1-ethanol, benzoglyoxaline, imidazoles, pyrroles, pyrroline, oxazole, isoxzzole, indazole or indolizine, and

Water.

2. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein the weight of this abrasive particle is 1000ppm to lower than 3000ppm.

3. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein the particle diameter of this abrasive particle is less than 90nm.

4. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein the particle diameter of this abrasive particle is less than 50nm.

5. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein this abrasive particle is selected from the silicon-dioxide of calcination; The silicon dioxide gel forming from the hydrolysis of water glass or potassium silicate or silane hydrolyzate and condensation; The aluminium dioxide of precipitation or calcination; The titanium dioxide of precipitation or calcination; Macromolecular material; The cohort that metal oxide and macromolecular material mixture form.

6. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein this abrasive particle is silicon dioxide gel.

7. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein this hydrogen peroxide accounts for 0.25 to 5 % by weight of constituent gross weight.

8. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein this accelerator accounts for 0.01 to 5 % by weight of constituent gross weight.

9. a kind of grinding composite that is simultaneously applicable to the copper metal planarization in first and second stage in two-stage copper metallization learn to grind processing procedure as claimed in claim 1, wherein this common corrosion inhibitor accounts for 0.001 to 1 % by weight of constituent gross weight.

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