Gold etching liquid capable of adjusting etching taper angle

Abstract

The invention relates to a gold etching solution capable of adjusting an etching taper angle. The etching solution is composed of iodine, iodide, a surfactant, a solubilizer and water. The surfactant is added into the gold etching liquid, so that the wettability of the etching liquid on the metal surface can be improved, and the etching taper angle can be adjusted within the range of 30-90 degrees according to the technological process requirement. And the solubilizer is used, so that the solubility of the gold complex in the etching solution can be improved, the influence of gold ions on the etching solution is reduced, and the solution substances are dispersed more uniformly. On the basis of an iodine and potassium iodide system, the surface active agent in a specific dosage range and the specific solubilizing agent are added, and the gold etching liquid which is controllable in etching taper angle, free of surface residues and stable and controllable in etching rate is prepared.

Description

Technical Field

[0001] The invention relates to the field of semiconductor chip manufacturing and packaging and testing, and in particular to a gold etching solution for adjusting an etching cone angle. Background Art

[0002] In the field of semiconductor manufacturing, gold etching solution and its etching method are crucial to the realization of high-performance semiconductor devices. With the rapid development of technologies such as the Internet, smart phones, and new energy vehicles, the demand for semiconductor chips continues to grow, and the requirements for chip performance are also increasing. The line width of the chip process continues to shrink, the ability to withstand high-voltage breakdown is enhanced, the speed of electrical signal transmission is accelerated, and the power consumption is reduced. Gold material has the characteristics of good ductility, good conductivity, high chemical stability, good corrosion resistance and high reliability. It is often used as a conductive layer of semiconductor devices to stably transmit electrical signals. In addition, gold can make finer and thinner wiring line widths, and can be well applied to chip manufacturing processes with reduced size.

[0003] In the semiconductor manufacturing process, the preparation of gold circuits also needs to go through a series of refined process flows, including sputtering coating, coating-exposure-development and etching steps to form a gold circuit with a specific structure and lay the foundation for subsequent coating and other processes of other circuit layers. The etching process plays a vital role in this. The etching of gold circuits in semiconductors often uses a special gold etching solution for wet etching to remove the gold metal that is not protected by the photoresist to form a circuit. While etching the gold metal downward, the etching solution will inevitably etch sideways, and the slope angle formed is called the etching cone angle. In theory, the larger the etching cone angle and the closer it is to 90°, the more consistent the upper and lower side etching of the gold circuit, and the better the electrical signal transmission performance. However, most gold metal wires belong to the intermediate circuit process, and other film layers need to be prepared on their upper part. If the etching cone angle is too large, the upper coating (usually only a few hundred nanometers thick) may break at the cone angle, causing the entire product to be scrapped due to circuit problems. On the contrary, when the gold circuit is located in the upper layer, it can have a larger etching cone angle to fully guarantee its electrical performance. Therefore, in the semiconductor process, it is particularly important to adjust the etching cone angle according to the position of the circuit layer. To achieve the above effect, the structure of the gold film layer needs to be strictly controlled to achieve stability. In the existing metal etching system, the etching rate of the iodide system is locally too fast and the etching cone angle is large, which causes damage to the chip circuit. Therefore, when etching the gold film layer structure, the etching liquid needs to be able to meet the requirements of stable etching rate, uniform etching morphology, and no circuit breakage. Summary of the invention

[0004] The invention aims to solve the problems of unstable etching rate of the existing gold etching solution, uneven etching morphology and easy breakage of the etching solution.

[0005] In order to solve the above problems, the present application is implemented through the following technical solutions: A gold etching solution for adjusting an etching cone angle comprises iodine, iodide, a surfactant, a solubilizing agent and water.

[0006] The gold etching solution is calculated by mass ratio of iodine: iodide: surfactant: solubilizer: water = 1-5: 5-15: 0.01-0.5: 1.5-4: 75.5-92.49.

[0007] The iodide in the gold etching solution is potassium iodide.

[0008] The surfactant in the gold etching solution is one or more of sodium N-lauroyl-N-methyltaurate, sodium N-oleoyl-N-methyltaurate, and sodium lauroyl isethionate.

[0009] The solubilizing agent in the gold etching solution is any one of hydroxytyrosol, 4-bromobenzyl alcohol and triethylsilanol.

[0010] The gold etching solution is calculated by mass ratio of iodine: iodide: surfactant: solubilizer: water = 3: 10: 0.15: 2.7: 84.15, wherein the surfactant is sodium lauroyl isethionate and the solubilizer is hydroxytyrosol, and the mixture is stirred and mixed to obtain the gold etching solution.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The addition of surfactants to the gold etching solution can reduce the surface tension of the etching solution and improve the liquid-mass exchange between the reaction products and the external solution on the reaction interface at the top of the metal film layer. According to the process requirements, the etching cone angle can be adjusted within the range of 30-90°.

[0012] 2. The use of solubilizers can increase the solubility of gold complexes in etching solution, make the effective substances in the solution more evenly distributed on the entire surface, and improve the uniformity of solution etching; at the same time, increase the wettability of the etching solution on the metal surface and adjust the etching cone angle.

[0013] 3. On the basis of the iodine and potassium iodide system, the present application adds a surfactant within a specific dosage range (one or more of sodium N-lauroyl-N-methyltaurate, sodium N-oleoyl-N-methyltaurate, sodium lauroyl isethionate) and a specific solubilizer (any one of hydroxytyrosol, 4-bromobenzyl alcohol, and triethylsilanol) to prepare a gold etching solution with controllable etching cone angle, no surface residue, and stable and controllable etching rate.

[0014] Among them, sodium N-lauroyl-N-methyltaurate, sodium N-oleoyl-N-methyltaurate, sodium lauroylhydroxyethyl sulfonate and the like compounds containing lauroyl, sulfonic acid and fatty acid sulfonylamides have better affinity and selectivity for organic matter than inorganic surfactants. When used in gold etching solution, the etching solution can preferentially infiltrate and adhere to the gold-photoresist interface compared to the gold-Si substrate interface, thereby accelerating the etching rate of the etching solution on the top of the gold film layer, thereby reducing the etching cone angle of the gold film layer.

[0015] On the other hand, polyhydroxy alcohols with benzene rings, halogenated polyhydroxy alcohols with benzene rings, hydroxytyrosol, 4-bromobenzyl alcohol, and triethylsilanol as solubilizers can increase the solubility of the complex generated by gold in the reaction in the etching solution, and can effectively disperse the complex accumulated on the metal surface, thereby effectively improving the uniformity of etching. At the same time, since the selected solubilizer is a polyhydroxy compound, it has good penetration and dispersion capabilities, and its use in combination with a surfactant can enhance the wetting effect of the surfactant, further improving the etching solution's ability to regulate the etching cone angle.

[0016] 4. Compared with straight-chain primary alcohols such as ethanol and propanol, hydroxytyrosol contains a benzene ring and multiple hydroxyl groups, which significantly increases the solubility of gold complexes, making the surface etching more uniform and residue-free. DETAILED DESCRIPTION

[0017] Hydroxytyrosol CAS No.: 10597-60-1, triethylsilanol CAS No.: 597-52-4, sodium N-oleoyl-N-methyltaurate CAS No.: 137-20-2.

[0018] Example 1 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0019] Example 2 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.01% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0020] Example 3 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.05% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0021] Example 4 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.2% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0022] Example 5 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.3% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0023] Example 6 According to the mass percentage, 1% iodine, 10% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0024] Example 7 According to the mass percentage, 5% iodine, 5% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0025] Example 8 According to the mass percentage, 3% iodine, 5% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0026] Example 9 According to the mass percentage, 3% iodine, 15% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% hydroxytyrosol are uniformly mixed, and then supplemented to 100% with ultrapure water, and stirred and mixed to obtain a gold etching solution.

[0027] Example 10 According to mass percentage, 3% iodine, 10% potassium iodide, 0.1% sodium N-lauroyl-N-methyltaurate, and 1.8% hydroxytyrosol are uniformly mixed, supplemented to 100% with ultrapure water, and stirred to obtain a gold etching solution.

[0028] Embodiment 11 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.3% sodium lauroyl isethionate, and 2.5% 4-bromobenzyl alcohol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred to obtain a gold etching solution.

[0029] Example 12 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.3% sodium N-oleoyl-N-methyltaurate, and 2.5% triethylsilanol were uniformly mixed, and then supplemented to 100% with ultrapure water, and stirred to obtain a gold etching solution.

[0030] Example 13 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.15% sodium lauroyl isethionate, and 2.7% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0031] Comparative Example 1 According to the mass percentage, 3% iodine and 10% potassium iodide were uniformly mixed, and water was added to make up to 100%, and the mixture was stirred and mixed to obtain a gold etching solution.

[0032] Comparative Example 2 According to the mass percentage, 3% iodine, 10% potassium iodide and 0.3% sodium lauroyl isethionate were uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0033] Comparative Example 3 According to the mass percentage, 3% iodine, 10% potassium iodide and 2% hydroxytyrosol were uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0034] Comparative Example 4 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.005% sodium lauroyl isethionate, and 0.5% hydroxytyrosol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution.

[0035] The amount of solubilizer and surfactant used is small, and the etching cone angle is only slightly reduced, and the effect is not achieved.

[0036] Comparative Example 5 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.5% sodium lauroyl isethionate, and 6% hydroxytyrosol are uniformly mixed, and then supplemented to 100% with ultrapure water, and stirred and mixed to obtain a gold etching solution.

[0037] The amount of solubilizer and surfactant used is too much, and the regulation of the etching cone angle has exceeded the ability range, and the etching cone angle has no obvious change.

[0038] Comparative Example 6 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.1% sodium lauroyl isethionate, and 2.5% ethanol are uniformly mixed, and then supplemented with ultrapure water to 100%, and stirred and mixed to obtain a gold etching solution. When ethanol is used, etching is uneven.

[0039] Comparative Example 7 According to the mass percentage, 3% iodine, 10% potassium iodide, 0.1% N-carbamoylmethyl ethanesulfonic acid, and 2% hydroxytyrosol are uniformly mixed, and then supplemented to 100% with ultrapure water, and stirred and mixed to obtain a gold etching solution.

[0040] When N-carbamoylmethylethanesulfonic acid, which also has a sulfonic acid group, is used as a surfactant, the etching uniformity is not effectively improved, and the etching rate is significantly reduced. N-carbamoylmethylethanesulfonic acid is not suitable for gold etching solutions in a potassium iodide system.

[0041] Etching experiment: The gold etching solution prepared in the above examples and comparative examples was stirred and immersed in the gold structure sheet with a film thickness of 30000Å at 25°C for etching until the gold structure sheet changed from gold to dark gray, and the time was recorded as EPD. The structure layer was photographed and measured using a scanning electron microscope to measure the etching cone angle of the gold film layer and recorded in Table 2. After etching, the photoresist on the upper part was removed from the gold structure sheet by using a tetramethylammonium hydroxide (TMAH) solution. The maximum line width and the minimum line width of the gold film layer pattern of the sample after etching were measured using a scanning electron microscope, and the difference between the maximum line width and the minimum line width was used as the standard for etching uniformity evaluation, and the results are shown in Table 2; At the same time, the silicon substrate gold film test piece with a film thickness of 3000Å ​​was stirred and immersed for etching for 30s. The thickness of the gold film layer before and after etching was measured using a four-point probe, and the gold etching rate (Å / s) was calculated to be (film thickness before etching - film thickness after etching) / etching time. Six gold test pieces were etched per cup of solution, and the average etching rate of the six pieces was taken as the etching rate of the etching solution for gold.

[0042] Table 1 Raw material ratio of gold etching solution

[0043] Table 2 Etching effect of gold etching solution with different ratios

[0044] The technical solution of the present invention is further explained in conjunction with specific embodiments. It is worth noting that the embodiments are only preferred embodiments of the present invention and should not be understood as limiting the present invention. The protection scope of the present invention shall be based on the contents recorded in the claims. Any modification or replacement of the technical solution of the present invention made by those skilled in the art without creative work shall fall within the protection scope of the present invention.

Claims

1. A gold etching solution for adjusting the etching cone angle, characterized in that: The gold etching solution comprises iodine, iodide, a surfactant, a solubilizing agent and water.

2. A gold etching solution for adjusting the etching cone angle according to claim 1, characterized in that: The gold etching solution is calculated by mass ratio of iodine: iodide: surfactant: solubilizer: water = 1-5: 5-15: 0.01-0.5: 1.5-4: 75.5-92.

49.

3. A gold etching solution for adjusting the etching cone angle according to claim 1, characterized in that: The iodide in the gold etching solution is potassium iodide.

4. The gold etching solution for adjusting the etching cone angle according to claim 1, characterized in that: The surfactant in the gold etching solution is one or more of sodium N-lauroyl-N-methyltaurate, sodium N-oleoyl-N-methyltaurate, and sodium lauroyl isethionate.

5. The gold etching solution for adjusting the etching cone angle according to claim 1, characterized in that: The solubilizing agent in the gold etching solution is any one of hydroxytyrosol, 4-bromobenzyl alcohol and triethylsilanol.

6. A gold etching solution for adjusting the etching cone angle according to claim 2, characterized in that: The gold etching solution is calculated by mass ratio of iodine: iodide: surfactant: solubilizer: water = 3: 10:0.15:2.7:84.15, wherein the surfactant is sodium lauroyl isethionate and the solubilizer is hydroxytyrosol.

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