Silicon surface thinning cleaning liquid process for 12-inch integrated circuit

Abstract

The invention discloses a silicon surface thinning cleaning liquid process for a 12-inch integrated circuit, which belongs to the technical field of silicon surface cleaning liquid production and comprises the following steps: preparing the following raw materials: 5-25% of hydrochloric acid, 10-20% of nitric acid, 10-20% of acetic acid and 0.1-0.5% of additive; s2, physically purifying the raw materials in the S1 to remove impurities; s3, after physical purification and impurity removal of the raw materials in the step S2 are completed, adding the raw materials subjected to physical purification and impurity removal into a reaction kettle through a pneumatic pump for mixing; by adding ammonium fluoride, acetic acid, phosphoric acid and fluoboric acid in a formula system, the defect that the etching rate is too fast and is not easy to control is overcome, and the removal capacity of an oxide layer on the silicon surface is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon surface cleaning solution production, and in particular relates to a silicon surface thinning cleaning solution process for 12-inch integrated circuits. Background Art

[0002] Silicon surface thinning cleaning fluid plays an important role in semiconductor manufacturing, especially in the production process of integrated circuits (ICs). These cleaning fluids are mainly used to remove pollutants and oxide layers on the surface of silicon wafers, improve the cleanliness of silicon wafers, and thus ensure the performance and reliability of chips. However, most existing cleaning fluid formulas use hydrofluoric acid and nitric acid as the main system. Although the etching rate is too fast, it is not easy to control, which may lead to uneven etching morphology and difficulty in controlling the amount of silicon loss. Therefore, we propose a silicon surface thinning cleaning fluid process for 12-inch integrated circuits. Summary of the invention

[0003] The present invention provides a silicon surface thinning cleaning liquid process for a 12-inch integrated circuit to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solution: a 12-inch integrated circuit silicon surface thinning cleaning liquid process, comprising the following steps: S1. Prepare raw materials: hydrochloric acid: 5%-25%, nitric acid: 10%-20%, acetic acid: 10%-20% and surfactant: 0.1%-0.5%; S2, physically purifying the raw materials in S1 to remove impurities; S3, after the physical purification of the raw materials in S2 is completed to remove impurities, the raw materials after physical purification and impurity removal are added to the reactor by a pneumatic pump for mixing; S4, after the raw materials in S3 are mixed, the mixed raw materials are circulated and mixed; S5. After circulating and mixing, pour it into the finished product tank through the pipeline for filtering and packaging.

[0005] Furthermore, in step S2, the specific method of physically purifying and removing impurities is: The purification and impurity removal methods for hydrochloric acid and nitric acid are: use vacuum multi-stage distillation to remove metal ions and other impurities in the products, and use nanofiltration and ultrafiltration to accurately control the particles of the products, with the controlled particle sizes including 0.1μm, 0.05μm and 0.2μm; The method for purifying and removing impurities from acetic acid is as follows: use molecular sieves to remove water, use anion and cation exchange resins to remove anions and cations, and then use nanofiltration and ultrafiltration to accurately control the particles of the product. The controlled particle sizes include 0.1μm, 0.05μm and 0.2μm.

[0006] Furthermore, in the step S4, the mixing capacity in the reactor is calculated as 10 cubic meters, the mixing time is two hours, and a built-in cooling water coil is used to cool the reaction process.

[0007] Furthermore, in the step S3, the reaction equation of the mixing method is: 2HNO3+3R=3RO+2NO+H2O; H + +NO3 - +2NO+H2O=3HNO2; 2HNO2+R=RO+2NO+H2O.

[0008] Furthermore, in the step S5, three cycles of mixing are performed by a circulating mixing device, and the three cycles of mixing time is 2 hours.

[0009] The beneficial effects of the present invention are: By adding ammonium fluoride, acetic acid, phosphoric acid and fluoroboric acid to the formula system, the disadvantage of the etching rate being too fast and difficult to control is improved. At the same time, surfactants and additives are added to optimize the etching morphology and enhance the ability to remove the oxide layer on the silicon surface. DETAILED DESCRIPTION

[0010] In order to further understand the content, features and effects of the present invention, the following embodiments are listed.

[0011] Embodiment 1: A silicon surface thinning cleaning liquid process for 12-inch integrated circuits comprises the following steps; S1. Prepare raw materials: hydrochloric acid: 5%, nitric acid: 10%, acetic acid: 10% and surfactant: 0.1%; S2. Physically purify the raw materials in S1 to remove impurities. The specific method of physical purification to remove impurities is: The purification and impurity removal methods for hydrochloric acid and nitric acid are: use vacuum multi-stage distillation to remove metal ions and other impurities in the products, and use nanofiltration and ultrafiltration to accurately control the particles of the products, with the controlled particle sizes including 0.1μm, 0.05μm and 0.2μm; The method for purifying and removing impurities from acetic acid is: using molecular sieves to remove water, then using anion and cation exchange resins to remove anions and cations, and then using nanofiltration and ultrafiltration to accurately control the particles of the product. The controlled particle sizes include 0.1μm, 0.05μm and 0.2μm; S3, after the physical purification of the raw materials in S2 is completed to remove impurities, the raw materials after physical purification and impurity removal are added to the reactor by a pneumatic pump for mixing. The mixing capacity in the reactor is calculated as 10 cubic meters, the mixing time is two hours, and the built-in cooling water coil is used to cool the reaction process; The reaction equation is: 2HNO3+3R=3RO+2NO+H2O; H + +NO3 - +2NO+H2O=3HNO2; 2HNO2+R=RO+2NO+H2O; Wherein R is a reducing agent.

[0012] S4, after the raw materials in S3 are mixed, the mixed raw materials are circulated and mixed. In the step S5, the circulated mixing device is used to circulate and mix three times, and the three circulated mixing time is 2 hours; S5. After circulating and mixing, pour it into the finished product tank through the pipeline for filtering and packaging.

[0013] Embodiment 2: S1. Prepare raw materials: hydrochloric acid: 5%, nitric acid: 10%, acetic acid: 10% and surfactant: 0.1%; S2. Physically purify the raw materials in S1 to remove impurities. The specific method of physical purification to remove impurities is: The purification and impurity removal methods for hydrochloric acid and nitric acid are: use vacuum multi-stage distillation to remove metal ions and other impurities in the products, and use nanofiltration and ultrafiltration to accurately control the particles of the products, with the controlled particle sizes including 0.1μm, 0.05μm and 0.2μm; The method for purifying and removing impurities from acetic acid is: using molecular sieves to remove water, then using anion and cation exchange resins to remove anions and cations, and then using nanofiltration and ultrafiltration to accurately control the particles of the product. The controlled particle sizes include 0.1μm, 0.05μm and 0.2μm; S3, after the physical purification of the raw materials in S2 is completed to remove impurities, the raw materials after physical purification and impurity removal are added to the reactor by a pneumatic pump for mixing. The mixing capacity in the reactor is calculated as 10 cubic meters, the mixing time is two hours, and the built-in cooling water coil is used to cool the reaction process; The reaction equation is: 2HNO3+3R=3RO+2NO+H2O; H + +NO3 - +2NO+H2O=3HNO2; 2HNO2+R=RO+2NO+H2O; S4, after the raw materials in S3 are mixed, the mixed raw materials are circulated and mixed. In the step S5, the circulated mixing device is used to circulate and mix three times, and the three circulated mixing time is 2 hours; S5. After circulating and mixing, pour it into the finished product tank through the pipeline for filtering and packaging.

[0014] Embodiment three: S1. Prepare raw materials: hydrochloric acid: 25%, nitric acid: 20%, acetic acid: 20% and surfactant: 0.5%; S2. Physically purify the raw materials in S1 to remove impurities. The specific method of physical purification to remove impurities is: The purification and impurity removal methods for hydrochloric acid and nitric acid are: use vacuum multi-stage distillation to remove metal ions and other impurities in the products, and use nanofiltration and ultrafiltration to accurately control the particles of the products, with the controlled particle sizes including 0.1μm, 0.05μm and 0.2μm; The method for purifying and removing impurities from acetic acid is: using molecular sieves to remove water, then using anion and cation exchange resins to remove anions and cations, and then using nanofiltration and ultrafiltration to accurately control the particles of the product. The controlled particle sizes include 0.1μm, 0.05μm and 0.2μm; S3, after the physical purification of the raw materials in S2 is completed to remove impurities, the raw materials after physical purification and impurity removal are added to the reactor by a pneumatic pump for mixing. The mixing capacity in the reactor is calculated as 10 cubic meters, the mixing time is two hours, and the built-in cooling water coil is used to cool the reaction process; The reaction equation is: 2HNO3+3R=3RO+2NO+H2O; H + +NO3 - +2NO+H2O=3HNO2; 2HNO2+R=RO+2NO+H2O; S4, after the raw materials in S3 are mixed, the mixed raw materials are circulated and mixed. In the step S5, the circulated mixing device is used to circulate and mix three times, and the three circulated mixing time is 2 hours; S5. After circulating and mixing, pour it into the finished product tank through the pipeline for filtering and packaging.

[0015] In this technical solution: The effect of adding acetic acid: When glacial acetic acid is used as a diluent, the degree of ionization of nitric acid is reduced, which reduces the reaction rate, thereby achieving a stable and controllable rate.

[0016] The effect of adding phosphoric acid: it can reduce the corrosion rate of silicon wafers without changing the corrosion morphology of the silicon wafer surface. The reaction rate is easy to control. Phosphoric acid does not participate in the corrosion reaction and cannot change the chemical kinetics, but it can increase the solution viscosity, increase the mass transfer resistance, and reduce the corrosion rate.

[0017] The effect of increasing fluoroboric acid: it increases the concentration of fluoride ions, thereby improving the etching and cleaning efficiency of the silicon surface oxide layer, and because it is a non-ionic fluoride ion, no free fluoride ions are produced during the reaction, and the waste liquid disposal process meets environmental protection requirements.

[0018] Increasing the effect of surfactant reduces the surface tension of the solution, improves the morphology of silicon surface etching and cleaning, and achieves uniform morphology of silicon surface after etching and cleaning.

[0019] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A 12-inch integrated circuit silicon surface thinning cleaning liquid process, characterized in that: The following steps are involved: S1. Prepare raw materials: hydrochloric acid: 5%-25%, nitric acid: 10%-20%, acetic acid: 10%-20% and surfactant: 0.1%-0.5%; S2, physically purifying the raw materials in S1 to remove impurities; S3, after the physical purification of the raw materials in S2 is completed to remove impurities, the raw materials after physical purification and impurity removal are added to the reactor by a pneumatic pump for mixing; S4, after the raw materials in S3 are mixed, the mixed raw materials are circulated and mixed; S5. After circulating and mixing, pour it into the finished product tank through the pipeline for filtering and packaging.

2. A 12-inch integrated circuit silicon surface thinning cleaning liquid process according to claim 1, characterized in that: In step S2, the specific method of physically purifying and removing impurities is: The purification and impurity removal methods for hydrochloric acid and nitric acid are: use vacuum multi-stage distillation to remove metal ions and other impurities in the products, and use nanofiltration and ultrafiltration to accurately control the particles of the products, with the controlled particle sizes including 0.1μm, 0.05μm and 0.2μm; The method for purifying and removing impurities from acetic acid is: using molecular sieves to remove water, using anion and cation exchange resins to remove anions and cations, and then using nanofiltration and ultrafiltration to accurately control the particles of the product. The controlled particle sizes include 0.1μm, 0.05μm and 0.2μm.

3. The process for cleaning the silicon surface for 12-inch integrated circuits according to claim 1, characterized in that: In the step S4, the mixing capacity in the reactor is calculated as 10 cubic meters, the mixing time is two hours, and a built-in cooling water coil is used to cool the reaction process.

4. The process for cleaning the silicon surface for thinning 12-inch integrated circuits according to claim 1, characterized in that: In the step S3, the reaction equation of the mixing method is: 2HNO3+3R=3RO+2NO+H2O; <h2 style=";text-align:left;direction:ltr">H<h2 style=";text-align:left;direction:ltr"> + <h2 style=";text-align:left;direction:ltr"> +NO3<h2 style=";text-align:left;direction:ltr"> - <h2 style=";text-align:left;direction:ltr"> +2NO+H2O=3HNO2; 2HNO2+R=RO+2NO+H2O.

5. The process for cleaning the silicon surface for thinning 12-inch integrated circuits according to claim 1, characterized in that: In the step S5, three circulation mixing is performed by a circulation mixing device, and the three circulation mixing time is 2 hours.