ZnS etching solution

Abstract

The invention provides a ZnS etching solution. The ZnS etching solution comprises the following components in percentage by mass: 40-80% of inorganic acid, 1-10% of organic acid, 0.1-1% of a thickening agent and the balance of deionized water. According to the etching solution, inorganic acid reacts with zinc sulfide to realize etching of a zinc sulfide film layer; the organic acid containing lone pair electrons can form coordinate bonds with zinc sulfide and is adsorbed on the surface of ZnS to reduce the etching rate, and the thickening agent is added to increase the viscosity of the liquid medicine, so that the activity range of the active H < + > acting on etching in the etching solution is narrowed, the etching solution has stable and controllable etching rate while ensuring the etching precision, and the etching efficiency is improved. And moreover, the method has the excellent characteristics of small lateral erosion, no stripping of photoresist, small CD loss and the like, and realizes accurate etching of complex patterns and shapes on the ZnS surface.

Description

Technical Field

[0001] The invention belongs to the intersecting field of compound semiconductor manufacturing technology and electronic chemical synthesis process technology, and specifically relates to a ZnS etching solution. Background Art

[0002] Semiconductor device manufacturing includes various processing techniques in multiple stages, specifically, atomic layer deposition, magnetron sputtering (which can sputter zinc sulfide), diffusion, photolithography, etching, cleaning and many other processes. Among them, etching has become an important process. According to the functional requirements of semiconductor devices, a highly selective etching solution is required to remove the target thin film layer in order to obtain the pattern required by the device, thereby realizing the function of the semiconductor.

[0003] Zinc sulfide (ZnS) is a compound semiconductor material with a high specific surface area, excellent fluorescence properties, and good electron transport properties. It can emit short-wavelength light such as blue light and purple light. By using such zinc sulfide compound semiconductors, LEDs and semiconductor lasers that can efficiently output blue light and purple light can be obtained. At the same time, ZnS is a wide bandgap semiconductor with large band gap, high transmittance, and high refractive index, so it has been widely used in optoelectronic materials and electronic devices.

[0004] Among them, the etching of ZnS film layer is a process of removing some substances on the surface of ZnS material by chemical or physical methods to form a specific pattern or shape. However, the mechanical grinding removal process using physical methods takes a long time, and it is difficult to polish the entire surface evenly, and the cost is high; in the wet chemical etching process, common reagents include acid, alkaline or other chemical reagents, which can react chemically with ZnS to remove the ZnS film layer, but the existing formulas in the industry have many problems such as too fast etching rate, difficult to control, severe side etching, etching residue, introduction of metal ions, and stripping of photoresist. Chinese patent document CN112011340A discloses a corrosive liquid and a corrosive method for corroding a zinc sulfide ZnS film on the surface of mercury cadmium telluride, including H2O as a solvent and a solute dissolved in H2O, wherein the solute includes potassium iodide KI, potassium hydroxide KOH and iodine I2. The corrosive liquid can react chemically with ZnS to corrode the ZnS film on the surface of mercury cadmium telluride and achieve precise control of the corrosion degree. However, the corrosion rate is uncontrollable, which is likely to damage the material and thus affect its performance.

[0005] Therefore, it is very necessary to study an etching solution that has controllable rate, small side etching and no stripping of photoresist for the surface film of ZnS material. Summary of the invention

[0006] The main purpose of the present invention is to provide a ZnS etching solution, which has stable and controllable etching rate while ensuring etching accuracy, small side etching, no stripping of photoresist, small CD loss and other excellent characteristics, so as to achieve accurate etching of complex patterns and shapes on the ZnS surface, avoid excessive damage to the material and thus affect its performance, and further promote the development of ZnS compound semiconductor technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A ZnS etching solution, comprising the following components by mass percentage:

[0009] Inorganic acid 40% to 80%, organic acid 1% to 10%, thickener 0.1% to 1%, and the balance is deionized water.

[0010] Furthermore, the inorganic acid is at least one of sulfuric acid, phosphoric acid, hydrochloric acid and nitric acid.

[0011] Furthermore, the organic acid is at least one of pyruvic acid, oxalic acid, β-hydroxybutyric acid, salicylic acid, and lactic acid.

[0012] Furthermore, the thickener is at least one of glycerol, phenoxyethanol, trihydroxy polyether, and coconut oil fatty acid diethanolamide.

[0013] The invention also provides a method for preparing the ZnS solution, which comprises weighing each component according to the formula ratio and mixing them uniformly.

[0014] The invention also provides an etching method of the ZnS etching solution, which uses the etching solution to etch the ZnS material to form a pattern of a specific shape.

[0015] Furthermore, the etching process includes: immersing the ZnS material in the etching solution, rinsing it with ultrapure water after etching, and blowing it dry with nitrogen to complete the etching process of the ZnS film layer.

[0016] Furthermore, the etching temperature is 50-70° C., and the time is 100% OE.

[0017] The etching solution of the present invention comprises an inorganic acid reacting with zinc sulfide to generate H2S gas and zinc salt, thereby etching the zinc sulfide film layer. The hydroxyl group in the organic acid has a lone electron pair and is easily adsorbed on the surface of the zinc sulfide film layer, and can form a coordination bond with zinc sulfide to form a protective film, which is adsorbed on the surface of ZnS to reduce the etching rate of ZnS. At the same time, the thickener added increases the viscosity of the solution, so that the active H2S gas in the etching solution that acts on the etching is reduced. +The activity range of the etching solution of the present invention becomes smaller, and the interaction of the three makes the etching rate of ZnS accurately controllable; the three work together in a suitable proportion to effectively improve the uniformity and efficiency of the etching solution, control the etching rate within a suitable range, reduce side erosion, and reduce CD loss.

[0018] The beneficial effects of the present invention are:

[0019] 1. The etching solution of the present invention is fluorine-free and low in toxicity. When etching the ZnS material, the ZnS film layer can have good stability and etching performance, and will not cause excessive damage to the material and thus affect its performance.

[0020] 2. The ZnS etching solution of the present invention introduces an organic acid containing a lone pair of electrons, which is adsorbed on the ZnS surface to stabilize the etching rate. At the same time, a thickener is added to increase the viscosity of the solution, so that the activity range of the active H+ in the etching solution that plays a role in etching is small, thereby making the etching rate of ZnS controllable, reducing side corrosion, and reducing CD loss.

[0021] 3. The etching solution of the present invention has no special requirements for the subsequent cleaning process, and the residue can be removed only by rinsing with pure water, and the operation process is simple. DETAILED DESCRIPTION

[0022] The embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0023] A ZnS etching solution, comprising the following components by mass percentage:

[0024] 40% to 80% of inorganic acid, 1% to 10% of organic acid, 0.1% to 1% of thickener and the balance is deionized water.

[0025] The hydrogen ions in the inorganic acid in the etching solution of the present invention react with ZnS to etch the ZnS film layer; the organic acid provides the lone electron pair of the hydroxyl group to form a coordination bond with the metal zinc to control the etching rate; the thickener controls the action range of the hydrogen ions in the solution to further control the etching rate; and the deionized water can prevent ions that have a negative impact on etching from being introduced into the etching solution, thereby maintaining high etching quality.

[0026] The dosage of the three components of the present invention is related to the degree of adjustment of the etching rate. If controlled within a preset range, the etching rate can be higher and more stable without causing over-etching, thereby achieving excellent properties such as stable and controllable etching rate, no stripping of the photoresist, and low CD loss.

[0027] The specific embodiments are as follows:

[0028] The ZnS etching solution of the invention comprises, by mass percentage, 40% to 80% of inorganic acid, 1% to 10% of organic acid, 0.1% to 1% of thickener, and the remaining component is deionized water.

[0029] Table 1 shows the components and contents of the etching solutions of Examples 1 to 19 and Comparative Examples 1 to 12. The ZnS etching solution of the present invention can be prepared by simply and evenly mixing the above components.

[0030] Table 1 Components and contents of etching solutions in Examples and Comparative Examples

[0031]

[0032]

[0033] Performance Test:

[0034] In order to investigate the influence of the inorganic acid, organic acid and thickener on the etching performance of the etching solution in the present invention, the etching experiment was carried out by the following technical means:

[0035] Cut the ZnS test piece with photoresist pattern into 1.6*1.6cm 2 The fragments were immersed in the ZnS etching solution in the above embodiment and comparative example, respectively, the etching temperature was 60°C, and 100% OE was etched. After etching, they were rinsed with ultrapure water and dried with nitrogen. After etching, the slices were photographed by SEM cross section to measure the etching rate, CD loss and surface photoresist shedding. The average etching rate and etching uniformity were calculated by multiple measurements, and the results are shown in Table 2.

[0036] Table 2 Etching effect of etching solution in the embodiment and comparative example

[0037]

[0038]

[0039] According to the results of the above embodiments and comparative examples, the ZnS etching solution provided by the present invention has a good etching effect. It can stably and uniformly etch the ZnS film layer at 60°C, and has excellent characteristics such as no stripping of the photoresist, no etching residue, and small CD loss.

[0040] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A ZnS etching solution, characterized in that: The etching solution comprises the following components by mass percentage: 40% to 80% of inorganic acid, 1% to 10% of organic acid, 0.1% to 1% of thickener, and the balance is deionized water.

2. The ZnS etching solution according to claim 1, wherein: The inorganic acid is at least one of sulfuric acid, phosphoric acid, hydrochloric acid and nitric acid.

3. The ZnS etching solution according to claim 1, characterized in that: The organic acid is at least one of pyruvic acid, oxalic acid, β-hydroxybutyric acid, salicylic acid and lactic acid.

4. The ZnS etching solution according to claim 1, characterized in that: The thickener is at least one of glycerin, phenoxyethanol, trihydroxy polyether and coconut oil fatty acid diethanolamide.

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