Oxidation layer polishing solution and application thereof

Abstract

The invention discloses an oxide layer polishing solution and application thereof. The oxide layer polishing solution comprises the following components in percentage by mass: 10%-20% of a grinding agent, 0.2%-1% of a pH regulator, 0.01%-0.05% of an auxiliary agent and deionized water, wherein the auxiliary agent is a compound containing a conjugated structure and containing amino and carboxyl. The chemical mechanical polishing solution for the oxide layer has the characteristics of high polishing rate, few corrosion pits, few residues of particles and metal ions and the like.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, and in particular to an oxide layer polishing liquid and application thereof. Background Art

[0002] With the rapid development of semiconductor technology and Moore's Law, chemical mechanical polishing (CMP) plays an increasingly important role in chip manufacturing and processing. Currently, CMP is the only technology that can achieve global planarization.

[0003] The chemical mechanical polishing process combines chemical polishing and mechanical polishing to form a new type of polishing process. The main consumables are polishing liquid and polishing pad. The abrasive in the polishing liquid and the polishing pad both play a role in mechanical removal. In addition, the chemical additives in the polishing liquid play a role in chemical corrosion. Under the combined action of chemical corrosion and mechanical friction, the polishing workpiece is ground and polished to obtain a high-quality surface.

[0004] As the process becomes lower and lower, the line width becomes smaller and smaller, and the requirements for defect control become more and more stringent. The defects in semiconductor chips can be roughly divided into erosion, dishing, particle residue, metal residue, corrosion pits, etc. As long as any kind of defect occurs, it is fatal to the yield of the chip. Therefore, it is necessary for FAB factories to reduce the occurrence of defects as much as possible, improve the yield, and ultimately obtain more profits. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an oxide layer polishing liquid, which can reduce corrosion pits, particles, metal residues and other problems while ensuring the polishing rate during the chemical mechanical polishing process by adding an auxiliary agent.

[0006] Another object of the present invention is to provide an application of an oxide layer polishing liquid in chemical mechanical polishing of an oxide layer.

[0007] In order to achieve the above invention object, the present invention adopts the following technical solution:

[0008] An oxide layer polishing liquid comprises the following components in percentage by mass: 10% to 20% of abrasive, 0.2% to 1% of pH regulator, 0.01% to 0.05% of auxiliary agent, and deionized water; wherein the auxiliary agent is a compound containing a conjugated structure and containing an amino group and a carboxyl group.

[0009] In a specific embodiment, the compound containing a conjugated structure and containing an amino group and a carboxyl group is azobenzene-4-benzoic acid.

[0010] In a specific embodiment, the abrasive is fumed silica, preferably commercial electronic grade fumed silica.

[0011] In a preferred embodiment, the specific surface area of ​​the fumed silica is 80 to 120 m 2 / g; further preferably, the particle size of the fumed silica in the aqueous solution is 100 to 180 nm.

[0012] In a specific embodiment, the pH adjusting agent is selected from KOH, NaOH and the like, preferably KOH.

[0013] In a specific embodiment, the pH value of the polishing liquid is 10-12.

[0014] In a specific embodiment, the deionized water is ultrapure water, and the resistivity of the ultrapure water is not less than 18 megohm.cm.

[0015] On the other hand, the aforementioned oxide layer polishing liquid is used in chemical mechanical polishing of oxide layers.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The oxide layer polishing liquid of the present invention reduces the corrosion pit defects caused by the corrosive effect of the polishing liquid by adding specific additives, and reduces the particle and metal residue problems caused by high abrasive concentration and high KOH addition amount, thereby achieving more effective application in the semiconductor field, especially in chemical mechanical polishing.

[0018] The oxide layer polishing liquid of the present invention can reduce the corrosion pit defects, as well as the particle and metal residue problems caused by high abrasive concentration and high KOH addition amount by adding an auxiliary agent. The auxiliary agent is a compound containing a conjugated structure and containing amino and carboxyl groups. The reason why it can reduce the corrosion pit defects, as well as the particle and metal residue problems caused by high abrasive concentration and high KOH addition amount is mainly due to the following reasons: First, the pH of the oxide layer polishing liquid is usually around 10-12. Under this pH value condition, the oxide layer surface is negatively charged and can be adsorbed on the surface by electrostatic action with the protonated amino group in the polymer compound to form a protective film, thereby reducing the occurrence of corrosion pits. In addition, the auxiliary agent is a compound containing a conjugated structure and containing amino and carboxyl groups. The auxiliary agent can reduce the corrosion pit defects, as well as the particle and metal residue problems caused by high abrasive concentration and high KOH addition amount. The compound contains benzene ring conjugation and double bond structure, which can quickly transfer charge, avoid charge concentration, and avoid the occurrence of corrosion pits; secondly, the carboxyl group carries a negative charge under alkaline conditions, which is opposite to the charge carried by the protonated amino group, and can reduce the electrostatic interaction with the surface of the oxide layer to a certain extent, so that the compound can be slightly adsorbed on the surface of the oxide layer to reduce the problem of particle residue caused by high concentration abrasives, and avoid the problem of too low polishing rate or cleaning residue; thirdly, the compound contains functional groups such as amino and carboxyl groups, which can provide a large number of lone pairs of electrons, which can be combined with the metal ions in the pH regulator in the form of coordination bonds to avoid excessive free metal ions from excessively remaining on the surface of the oxide layer. Through the above effects, the corrosion pit defects, as well as the particle and metal residue problems caused by high abrasive concentration and high KOH addition, can be greatly reduced, thereby improving the yield of the chip. DETAILED DESCRIPTION

[0019] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0020] A polishing liquid for an oxide layer comprises the following components in percentage by mass: 10% to 20% abrasive, 0.2% to 1% pH regulator, 0.01% to 0.05% auxiliary agent, and deionized water; the auxiliary agent is a compound having a conjugated structure and containing amino and carboxyl groups, preferably azobenzene-4-benzoic acid. For example, taking the polishing liquid as 100%, it comprises 10% to 20% abrasive, 0.2% to 1% pH regulator, 0.01% to 0.05% auxiliary agent, and the remainder is deionized water. It is well known to those skilled in the art that other commonly used auxiliary agents, such as fungicides, etc., can be added to the polishing liquid according to process requirements, and after adding a small amount of fungicide, the remainder is water.

[0021] The abrasive agent is, for example, fumed silica, which may be commercial fumed silica, preferably having a specific surface area of ​​80 to 120 m 2 / g of fumed silica, the effective particle size of silica colloidal particles of the aqueous solution of the fumed silica dissolved in water is 100nm to 180nm, for example, 120nm, 150nm, 160nm, 170nm, etc. The effective particle size can be obtained by, for example, dynamic light scattering DLS method. The mass percentage of fumed silica in the polishing liquid is 10% to 20%, for example, including but not limited to 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0022] The pH regulator is selected from one or more substances such as KOH and NaOH, preferably KOH. The mass percentage content of the pH regulator in the polishing liquid is 0.2% to 1%, for example, including but not limited to 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

[0023] The auxiliary agent is a compound containing a conjugated structure and an amino group and a carboxyl group, preferably azobenzene-4-benzoic acid. The mass percentage content of the protective auxiliary agent in the polishing liquid is 0.01% to 0.05%, for example, including but not limited to 0.01%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%.

[0024] Generally, the pH value of the oxide layer polishing liquid of the present invention is 10-12, and can be adjusted by using an acid or an alkali, for example, potassium hydroxide or nitric acid.

[0025] The present invention is further explained below by more specific examples, but does not constitute any limitation.

[0026] The main sources of raw materials used in the following examples or comparative examples are as follows:

[0027] Fumed silica, AERISOL from Evonik, Germany, micron grade, specific surface area 90g / m 2 ;

[0028] Azobenzene-4-benzoic acid, Sinopharm Group Co., Ltd.

[0029] The main detection methods are as follows:

[0030] Polishing rate MRR (angstroms / minute): After the oxide layer wafer is chemically mechanically polished, the thickness difference and mass difference of the oxide layer wafer before and after polishing are measured with a thickness gauge and a balance to evaluate the polishing rate;

[0031] Particle residue: KLA's wafer defect detector SP2 is used to detect residual particles on the polished oxide layer wafer;

[0032] Etching pits: The surface of the oxide layer wafer is inspected by scanning electron microscope to find the etching pits on the surface of the wafer;

[0033] Metal ion residue: The residual metal ion test is performed on the oxide layer wafer after polishing and cleaning using ICP equipment.

[0034] The polishing liquids of the following examples and comparative examples were prepared according to the ingredients and contents of the components in the following table.

[0035] A chemical mechanical polishing liquid was prepared according to the formula in Table 1, mixed evenly, the pH value was adjusted to 11 with nitric acid or KOH, and water was added to make up the mass percentage to 100% to obtain an oxide layer polishing liquid of each embodiment of the present invention and the comparative example.

[0036] Table 1 Polishing liquid formula table of examples and comparative examples

[0037]

[0038] The wafers containing the oxide layer were polished using the chemical mechanical polishing liquids of Examples 1 to 5 and Comparative Examples 1 to 6, respectively. The polishing conditions were: polishing with a Mirra polisher, using an IC1010 polishing pad, a polishing pressure of 4.2 psi, and a polishing liquid flow rate of 150 mL / min. The polishing rate of the above polishing liquid on silicon oxide was measured, and the scratches and particle residues were detected using an sp defect detector at the same time. The test results are shown in Table 2.

[0039] Table 2 Performance test results of polishing liquids of embodiments and comparative examples

[0040]

[0041]

[0042] From the above Example 3 and Comparative Examples 1-2, it can be found that the concentration of the abrasive has a great influence on the polishing rate and the particle residue.

[0043] It can be found from the above Example 3 and Comparative Examples 3 to 4 that the pH adjuster content has a great influence on the polishing rate, the residual particles and the residual metal ions.

[0044] It can be found from the above Example 3 and Comparative Examples 5 to 6 that the concentration of azobenzene-4-benzoic acid has a significant effect on the polishing rate, metal residue and particle residue within a certain range.

[0045] In summary, compared with the prior art, the polishing liquid of the present invention is used in the chemical mechanical polishing process of the oxide layer. After using fumed silica as an abrasive and adding an appropriate amount of azobenzene-4-benzoic acid substance and a pH adjuster, there is a significant improvement in the number of corrosion pits and the residual metal ions and particles.

[0046] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. An oxide layer polishing liquid, characterized in that: The invention comprises the following components in percentage by weight: 10% to 20% of abrasive, 0.2% to 1% of pH regulator, 0.01% to 0.05% of auxiliary agent, and deionized water; wherein the auxiliary agent is a compound containing a conjugated structure and containing an amino group and a carboxyl group.

2. The oxide layer polishing liquid according to claim 1, characterized in that: The compound containing a conjugated structure, an amino group and a carboxyl group is azobenzene-4-benzoic acid.

3. The oxide layer polishing liquid according to claim 1, characterized in that: The abrasive is fumed silica, preferably commercial electronic grade fumed silica.

4. The oxide layer polishing liquid according to claim 4, characterized in that: The specific surface area of ​​the fumed silica is 80 to 120 m 2 / g; preferably, the particle size of the fumed silica in the aqueous solution is 100-180 nm.

5. The oxide layer polishing liquid according to claim 1, characterized in that: The pH adjuster is selected from at least one of KOH and NaOH, preferably KOH.

6. The oxide layer polishing liquid according to claim 1, characterized in that: The pH value of the oxide layer polishing liquid is 10-12.

7. The oxide layer polishing liquid according to claim 1, characterized in that: The deionized water is ultrapure water, and the resistivity of the ultrapure water is not less than 18 MΩ.CM.

8. Use of the oxide layer polishing liquid according to any one of claims 1 to 7 in chemical mechanical polishing of oxide layers.

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