CN114686116A

CN114686116A - Chemical mechanical polishing liquid and use method thereof

Info

Publication number: CN114686116A
Application number: CN202011626136.5A
Authority: CN
Inventors: 姚颖; 荆建芬; 倪宇飞; 周文婷; 宋凯; 蔡鑫元; 周靖宇; 李昀; 陆弘毅; 魏佳
Original assignee: Anji Microelectronics Shanghai Co Ltd
Current assignee: Anji Microelectronics Shanghai Co Ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2022-07-01

Abstract

The invention provides a chemical mechanical polishing solution for barrier layer planarization and a using method thereof. The chemical mechanical polishing solution comprises grinding particles, azole compounds, a complexing agent, an oxidizing agent, water-soluble cellulose and water. The chemical mechanical polishing solution has certain repair capability on the dishing and medium layer erosion after the previous copper polishing, has no obvious influence on the removal rate of tantalum, copper, silicon dioxide (TEOS) and low dielectric constant materials, and meets the requirements on the polishing rate, rate selection ratio and polished surface morphology of various materials in the polishing process of the barrier layer.

Description

Chemical mechanical polishing liquid and use method thereof

Technical Field

The invention relates to the field of chemical mechanical polishing, in particular to a chemical mechanical polishing solution for barrier layer planarization and a use method thereof.

Background

In the integrated circuit manufacturing, the standard of the interconnection technology is increasing, and with the increase of the number of interconnection layers and the reduction of the process feature size, the requirement on the surface flatness of the silicon wafer is higher and higher, and without the capability of planarization, the creation of complex and dense structures on the semiconductor wafer is very limited, and the chemical mechanical polishing process CMP is the most effective method for achieving the planarization of the whole silicon wafer.

The CMP process is the polishing of the surface of the integrated circuit using an abrasive-containing mixture. In a typical chemical mechanical polishing process, a substrate is brought into direct contact with a rotating polishing pad, and a carrier is used to apply pressure to the backside of the substrate. During polishing, the pad and platen are rotated while maintaining a downward force on the back surface of the substrate, and an abrasive and chemically reactive solution (commonly referred to as a slurry or slurry) are applied to the pad, which reacts chemically with the film being polished to begin the polishing process.

With the development of integrated circuit technology to 45nm and below technology nodes and the sharp increase of interconnection wiring density, the RC coupling parasitic effect brought by resistance and capacitance in an interconnection system is rapidly increased, and the speed of a device is influenced. To reduce this effect, a low dielectric constant (low k) material must be used to reduce the parasitic capacitance between adjacent metal lines, and the introduction of the low k material presents a significant challenge to the process technology, especially the Chemical Mechanical Polishing (CMP) process, due to its weak mechanical strength. In the CMP process, it is required to satisfy not only the requirements of polishing rate and selectivity of various materials in the barrier polishing process, but also a strong ability to correct defects on the surface of a semiconductor device.

Therefore, in order to solve the problems in the prior art, a chemical mechanical polishing solution which is suitable for polishing a barrier layer in a copper interconnection process, can realize high removal rate of the barrier layer and a dielectric material under a mild condition, and can well control Dishing (Dishing) and dielectric layer Erosion (Erosion) is a problem to be solved in the industry.

Disclosure of Invention

In order to overcome the technical defects, the invention provides a chemical mechanical polishing solution for polishing a barrier layer, which is prepared by adding water-soluble cellulose and adjusting the content of the cellulose to adjust the repair capacity of the barrier layer after polishing on the dish-shaped recess and dielectric layer erosion after polishing on the front-process copper, has no obvious influence on the removal rate of tantalum, copper, silicon dioxide (TEOS) and Low-k materials, and meets the requirements on the polishing rate and rate selection ratio of various materials in the polishing process.

The invention provides a chemical mechanical polishing solution which comprises abrasive particles, azole compounds, a complexing agent, an oxidizing agent, water-soluble cellulose and water.

Preferably, the water-soluble cellulose is selected from one of hydroxyethyl cellulose, hydroxypropyl cellulose and/or hydroxypropyl methyl cellulose.

Preferably, the viscosity average molecular weight of the water-soluble cellulose is 100000-5000000.

Preferably, the viscosity average molecular weight of the water-soluble cellulose is 200000-.

Preferably, the mass percentage concentration of the water-soluble cellulose is 0.0005-0.2%.

Preferably, the mass percentage concentration of the water-soluble cellulose is 0.001-0.1%.

Preferably, the abrasive particles are silica; the content of the grinding particles is 2-15% by mass; the abrasive particles have a particle size of 20-120 nm.

Preferably, the azole compound is one or more selected from benzotriazole, methylbenzotriazole, 1, 2, 4-triazole, 3-amino-1, 2, 4-triazole, 4-amino-1, 2, 4-triazole, carboxyl benzotriazole, 5-methyl tetrazole, 5-amino-tetrazole, 5-phenyl tetrazole, mercapto phenyl tetrazole, benzimidazole, naphthotriazole and/or 2-mercapto-benzothiazole.

Preferably, the azole compound is 0.001-0.5% by mass.

Preferably, the complexing agent is one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, 2-phosphonobutane-1, 2, 4-tricarboxylic acid, aminotrimethylenephosphonic acid, hydroxyethylenediphosphonic acid, ethylenediaminetetramethylenephosphonic acid, 2-hydroxyphosphonoacetic acid, polyaminopolyetherylmethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, ethylenediamine, glycine, alanine and/or ethylenediaminetetraacetic acid.

Preferably, the complexing agent accounts for 0.01-2% of the total mass of the composition.

Preferably, the oxidizing agent is hydrogen peroxide; the mass percentage content of the oxidant is 0.05% -1%.

Preferably, the pH value of the chemical mechanical polishing solution is 8-12.

The invention also discloses a using method of the chemical mechanical polishing solution, and the chemical mechanical polishing solution is used for barrier layer planarization.

The chemical mechanical polishing solution not only meets the requirements of removal rate and selection ratio of various materials in the process of polishing the barrier layer, but also can effectively correct and control the disc-shaped recess and the erosion of the dielectric layer.

Detailed Description

The advantages of the invention are further illustrated below by way of examples, without thereby restricting the invention to the scope of the examples described.

The chemical mechanical polishing solution can be prepared by the following method: mixing the components except oxidant at a certain proportion, and adding pH regulator (such as KOH or HNO)₃) Adjusting to the required pH value, adding an oxidant before use, and mixing uniformlyCan be prepared.

The reagents and starting materials used in the present invention are commercially available.

Table 1 shows the contents of the respective components in comparative examples 1 to 2 and 1 to 13 of the present invention. When preparing the polishing solution according to the formulation shown in Table 1, the components except the oxidizing agent are first mixed uniformly and then KOH or HNO is added₃The slurry is adjusted to the desired pH. And finally, adding an oxidizing agent before using the polishing solution, and uniformly mixing. The balance of water.

TABLE 1 Components and their amounts for comparative examples 1-2 and examples 1-17

Effects of the embodiment

Copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric material (BD) blank wafers were polished using the polishing solutions of comparative examples 1-2 and examples 1-17, respectively, under the following conditions, and the effects of the different polishing solutions on the polishing rates of copper (Cu), tantalum (Ta), silicon dioxide (TEOS), and low dielectric material (BD) were compared.

The specific polishing conditions were: the polishing machine is a 12' Reflexion LK machine, the polishing pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is 93/87rpm, the flow rate of the polishing solution is 300ml/min, and the polishing time is 1 min. The specific resistance of copper and tantalum before and after polishing was measured with a metal thin film thickness gauge, the thickness of copper and tantalum before and after polishing was calculated to obtain the removal rate of copper and tantalum, the thickness of TEOS and BD before and after polishing was measured with a non-metal thin film thickness gauge to obtain the removal rate of TEOS and BD, and the polishing results are shown in table 2.

TABLE 2 results of polishing Rate test of comparative example 1 and examples 1-17

As can be seen from Table 2, compared with comparative example 1, the polishing solutions 1 to 17 of the present invention, after adding water-soluble celluloses of different molecular weights and different contents, did not affect the removal rates of the barrier layer Ta, silicon dioxide (TEOS) and the low dielectric material BD, thereby ensuring shorter polishing time and improving productivity.

Effect of embodiment two

Patterned copper wafers were polished under the following conditions using comparative examples 1-2 and examples 1-4.

The graphic chip is a commercially available 12-inch Sematech754 graphic chip, and the film material is copper/tantalum nitride/TEOS from top to bottom.

The polishing process comprises three steps, wherein in the first step, most of copper is removed by using a commercially available copper polishing solution; secondly, removing residual copper by using a commercially available copper polishing solution; and thirdly, removing the barrier layer (tantalum/tantalum nitride) and part of TEOS by using the polishing solution for the barrier layer of the invention and stopping on the TEOS layer.

Polishing conditions: the polishing machine is a 12' Reflexion LK machine, the polishing pad is a Fujibo pad, the down pressure is 1.5psi, the rotation speed is 93/87rpm, the flow rate of the polishing solution is 300ml/min, and the polishing time is 70 s.

TABLE 3 comparison of corrective power after polishing of comparative examples 1-2 and examples 1-4 patterned copper wafers

Wherein, the dishing recess refers to a dishing recess on the metal pad before the barrier layer is polished, the dielectric erosion refers to a dielectric erosion of the barrier layer on a dense line region (50% copper/50% dielectric layer) with a line width of 0.18 micron and a density of 50%,

comparing comparative examples 1-2 with example 1, it can be seen that the polishing liquid has no ability to correct the dishing defect on the wafer surface even though the polishing rate of the polishing liquid for each material is still acceptable when the azole compound alone or the cellulose alone is used. When the azole compound and the cellulose are used simultaneously, compared with comparative examples 1-2, the water-soluble cellulose added in examples 1-4 can better correct the dishing and dielectric layer erosion generated on the wafer in the previous process (after copper polishing) due to the synergistic effect of the water-soluble cellulose and the azole compound, so that the polished copper wafer has better wafer morphology.

Effect example III

Patterned copper wafers were polished under the following conditions using comparative examples 1-2 and examples 10-13.

The graphic chip is a commercially available 12-inch Sematech754 graphic chip, and the film layer material is copper/tantalum nitride/TEOS/BD from top to bottom.

The polishing process is divided into three steps, wherein in the first step, most of copper is removed by using commercially available copper polishing solution; secondly, removing residual copper by using a commercially available copper polishing solution; the third step is to remove the barrier layer (tantalum/tantalum nitride), silicon dioxide TEOS, and a portion of BD with the inventive barrier polishing slurry and finally stop on the BD layer.

Polishing conditions: the polishing machine is a 12' Reflexion LK machine, the polishing pad is Fujibo pad, the downward pressure is 1.5psi, the rotation speed is 93/87rpm, the flow rate of the polishing solution is 300ml/min, and the polishing time is 70 s.

TABLE 4 comparison of corrective power after polishing of comparative examples 1-2 and examples 10-13 patterned copper wafers

As can be seen from Table 4, compared with the polishing solutions of comparative examples 1 and 2, the polishing solutions of examples 10 to 13, which are added with water-soluble cellulose and act synergistically with azole compounds, can better correct dishing and dielectric erosion generated on the wafer in the previous process (after copper polishing), so that the polished copper wafer has better wafer morphology. Therefore, the polishing solution of the invention is also suitable for polishing the barrier layer in the low dielectric material-copper interconnection process.

It should be understood that wt% in the present invention refers to mass percentage.

It should be noted that the embodiments of the present invention have been described in terms of preferred embodiments, and not by way of limitation, and that those skilled in the art can make modifications and variations of the embodiments described above without departing from the spirit of the invention.

Claims

1. A chemical mechanical polishing liquid is characterized in that,

comprises grinding particles, azole compounds, complexing agents, oxidizing agents, water-soluble cellulose and water.

2. The chemical mechanical polishing solution according to claim 1,

the water-soluble cellulose is selected from one of hydroxyethyl cellulose, hydroxypropyl cellulose and/or hydroxypropyl methyl cellulose.

3. The chemical mechanical polishing solution according to claim 1,

the viscosity average molecular weight of the water-soluble cellulose is 100000-5000000.

4. The chemical mechanical polishing solution according to claim 3,

the viscosity average molecular weight of the water-soluble cellulose is 200000-3000000.

5. The chemical mechanical polishing solution according to claim 1,

the mass percentage concentration of the water-soluble cellulose is 0.0005-0.2%.

6. The chemical mechanical polishing solution according to claim 5,

the mass percentage concentration of the water-soluble cellulose is 0.001-0.1%.

7. The chemical mechanical polishing solution according to claim 1,

the abrasive particles are silicon dioxide;

the content of the grinding particles is 2-15% by mass;

the abrasive particles have a particle size of 20-120 nm.

8. The chemical mechanical polishing solution according to claim 1,

the azole compound is one or more selected from benzotriazole, methyl benzotriazole, 1, 2, 4-triazole, 3-amino-1, 2, 4-triazole, 4-amino-1, 2, 4-triazole, carboxyl benzotriazole, 5-methyl tetrazole, 5-amino-tetrazole, 5-phenyl tetrazole, mercapto phenyl tetrazole, benzimidazole, naphthotriazole and/or 2-mercapto-benzothiazole.

9. The chemical mechanical polishing solution according to claim 1,

the azole compound accounts for 0.001-0.5% by mass.

10. The chemical mechanical polishing solution according to claim 1,

the complexing agent is one or more of oxalic acid, malonic acid, succinic acid, citric acid, tartaric acid, 2-phosphonic butane-1, 2, 4-tricarboxylic acid, amino trimethylene phosphonic acid, hydroxyethylidene diphosphonic acid, ethylene diamine tetramethylene phosphonic acid, 2-hydroxyphosphonoacetic acid, polyaminopolyether methylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, ethylenediamine, glycine, alanine and/or ethylene diamine tetraacetic acid.

11. The chemical mechanical polishing solution according to claim 1,

the mass percentage content of the complexing agent is 0.01-2%.

12. The chemical mechanical polishing solution according to claim 1,

the oxidant is hydrogen peroxide;

the mass percentage content of the oxidant is 0.05% -1%.

13. The chemical mechanical polishing solution according to claim 1,

the pH value of the chemical mechanical polishing solution is 8-12.

14. A method for using chemical mechanical polishing solution is characterized in that,

use of a chemical mechanical polishing liquid according to any of claims 1 to 13 for barrier planarization.