Etching solution for stably etching molybdenum-containing metal lamination

Abstract

The invention provides an etching solution for stably etching a molybdenum-containing metal lamination. The etching solution comprises 60-70% of phosphoric acid, 1-5% of nitric acid, 10-20% of acetic acid, 1.5-8% of an additive and the balance of ultrapure water. The MoOx / Mo / Al / Mo laminated layer is etched by the etching solution, the top molybdenum and the bottom molybdenum are both reduced slightly relative to the aluminum layer, and the variances of the critical dimensional deviation (CD Bias), the inclination angle (Taper), the dimensional deviation (Mo Tip) of the top molybdenum relative to the aluminum and the dimensional deviation (Mo Tail) of the bottom molybdenum relative to the aluminum are remarkably reduced, so that the morphology and the size of the etched MoOx / Mo / Al / Mo laminated layer are more uniform, and the improvement of the product etching yield is facilitated.

Description

Technical Field

[0001] The invention belongs to the cross field of metal wet etching and semiconductor display technology, and in particular relates to an etching solution for stably etching a molybdenum-containing metal stack. Background Art

[0002] In recent years, China's integrated circuit and display panel industries have experienced rapid development. Liquid crystal display (TFT-LCD) has become the mainstream flat panel display technology with its outstanding advantages and is widely used in many fields, enabling modern electronic devices to realize the concept of "Internet of Everything" in terms of interaction and operation. Due to its excellent conductivity, low preparation difficulty, large reserves and low cost, aluminum is widely used in the manufacture of gates and source and drain electrodes in TFT-LCD. The metal film layer used for circuit layout needs to be etched to form a specific pattern. Commonly used etching methods include dry etching and wet etching. The equipment and reagents for dry etching are expensive, the operation is complicated, and it is easy to cause damage to the substrate. The cost of wet etching is low, the reaction time is short and the operation is convenient. Therefore, wet etching is widely used in a variety of large-scale production and manufacturing.

[0003] During etching Mo / Al / Mo / MoO x During lamination, if the side etching of molybdenum is less than that of aluminum, it means that molybdenum tailing occurs. If the side etching of molybdenum is greater than that of aluminum, it means that molybdenum indentation occurs. x When etching stacked layers, based on different application requirements, the etching solution will be required to etch Mo / Al / Mo / MoO x When stacking, a small indentation or a small tailing occurs. In some processing procedures in the field of display technology, molybdenum tailing will affect the product's display effect, service life, circuit voltage stability and other technical indicators. Therefore, sometimes the etching solution is required to etch Mo / Al / Mo / MoO x During the lamination process, molybdenum tailing is avoided and the indentation value of molybdenum is reduced as much as possible. The phosphoric acid / nitric acid / acetic acid etching system is often used for etching of molybdenum-aluminum metal laminations due to its good stability and high cost performance. Based on this etching system, in the existing etching formula, although the molybdenum indentation value can be reduced by adjusting the formula components, the size of the indentation value cannot be stably controlled. During batch etching, the molybdenum indentation value fluctuates greatly, resulting in low product yield, increased etching cost and reduced production efficiency. Therefore, it is necessary to design an etching solution formula that can not only meet the requirements of a smaller molybdenum indentation value, but also make the indentation value more stable, so as to etch a product with a more uniform morphology. Summary of the invention

[0004] Based on the above problems, the present invention provides an etching solution for stably etching molybdenum-containing metal stacks, comprising the following components: 60-70% phosphoric acid, 1-5% nitric acid, 10-20% acetic acid, 1.5%-8% additives, and the balance is ultrapure water.

[0005] The additives include additive 1, additive 2 and additive 3; the additive 1 includes one or more of n-heptanoic acid, pimelic acid, sodium dodecylbenzene sulfonate or ammonium lauryl sulfate.

[0006] The additive 2 includes one or more of diethylene glycol butyl ether, monoethanolamine, triethanolamine or imidazole.

[0007] The additive 3 includes one or more of phosphate, nitrate, molybdate or oxalate.

[0008] The salt of the additive 3 is selected from one or more of sodium salt, potassium salt or ammonium salt.

[0009] The dosage of the additive 1 is 0.005-0.02%, the dosage of the additive 2 is 0.3-4.5%, and the dosage of the additive 3 is 1.5-3%. An etchant for stably etching molybdenum-containing metal stacks, used for MoO x / Mo / Al / Mo metal stack etching, the indentation value and variance of the top Mo layer relative to the Al layer after etching are 0.01~0.04um and 3~15nm, respectively, and the indentation value and variance of the bottom Mo layer relative to the Al layer are 0~8nm and 1~4nm, respectively.

[0010] The beneficial effect of the present invention is that it can be used for etching of molybdenum-aluminum stacks to adjust the size deviation of the etched morphology and improve the product display effect and yield. The top molybdenum and the bottom molybdenum are slightly indented relative to the aluminum layer, and the variance of the critical dimension deviation (CD Bias), the tilt angle (Taper), the size deviation of the top molybdenum relative to aluminum (Mo Tip) and the size deviation of the bottom molybdenum relative to aluminum (Mo Tail) are significantly reduced, indicating that the morphology size after etching with the etching solution is more uniform, which is conducive to improving the yield of product etching. DETAILED DESCRIPTION

[0011] The embodiments of the present invention will be described in detail below in conjunction with the examples. The following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. The experimental conditions not clearly marked in the examples are assumed to be selected according to conventional methods and conditions in the art or the product manual.

[0012] The substrate used in the embodiment is consistent with that in the comparative example, and the metal film layer is MoO x / Mo / Al / Mo, film thickness is 500 / 150 / 3000 / 550 (unit: angstrom).

[0013] Preparation of etching solution: Phosphoric acid, nitric acid, acetic acid, additives and the remainder of ultrapure water are mixed according to the components in Table 1.

[0014] Table 1 Etching solution formula of embodiment and comparative example (unit: %)

[0015] The MoOx / Mo / Al / Mo metal film layer was etched using the etching solutions of the above embodiments and comparative examples, and then a scanning electron microscope was used to detect the half-edge critical dimension deviation (CD Bias) of aluminum relative to the photoresist, the taper, the dimension deviation (Mo Shrink) of the top molybdenum relative to aluminum, and the dimension deviation (Mo Undercut) of the bottom molybdenum relative to aluminum.

[0016] Table 2 Etching data of examples and comparative examples

[0017] In the table, “-” means that aluminum exceeds molybdenum after etching. x / Mo / Al / Mo metal film layer, the top molybdenum and bottom molybdenum are slightly indented relative to the aluminum layer, and the indentation values ​​are 0.01~0.04um and 0~8 nm respectively. In addition, the variances of the half-edge critical dimension deviation (CD Bias) of aluminum relative to the photoresist, the tilt angle (Taper), the size deviation of the top molybdenum relative to aluminum (Mo Tip) and the size deviation of the bottom molybdenum relative to aluminum (Mo Tail) are small. In particular, the indentation variances of the top molybdenum and bottom molybdenum relative to the aluminum layer are 3~15nm and 1~4nm respectively; the above data show that the etching stability of this etching solution is excellent, and the morphology of the etched metal stack is more uniform.

Claims

1. An etching solution for stably etching a molybdenum-containing metal stack, characterized in that: It includes the following ingredients: 60-70% phosphoric acid, 1-5% nitric acid, 10-20% acetic acid, 1.5%-8% additives, and the balance is ultrapure water.

2. The etching solution for stably etching a molybdenum-containing metal stack according to claim 1, characterized in that: The additives include additive 1, additive 2 and additive 3; the additive 1 includes one or more of n-heptanoic acid, pimelic acid, sodium dodecylbenzene sulfonate or ammonium lauryl sulfate.

3. The etching solution for stably etching a molybdenum-containing metal stack according to claim 2, characterized in that: The additive 2 includes one or more of diethylene glycol butyl ether, monoethanolamine, triethanolamine or imidazole.

4. The etching solution for stably etching a molybdenum-containing metal stack according to claim 3, characterized in that: The additive 3 includes one or more of phosphate, nitrate, molybdate or oxalate.

5. The etching solution for stably etching a molybdenum-containing metal stack according to claim 4, characterized in that: The salt of the additive 3 is selected from one or more of sodium salt, potassium salt or ammonium salt.

6. The etching solution for stably etching a molybdenum-containing metal stack according to claim 5, characterized in that: The dosage of the additive 1 is 0.005-0.02%, the dosage of the additive 2 is 0.3-4.5%, and the dosage of the additive 3 is 1.5-3%.

7. Use of the etching solution according to any one of claims 1 to 6, characterized in that: For MoO x / Mo / Al / Mo metal stack etching, the indentation value and variance of the top Mo layer relative to the Al layer after etching are 0.01~0.04um and 3~15nm, respectively, and the indentation value and variance of the bottom Mo layer relative to the Al layer are 0~8nm and 1~4nm, respectively.

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