Etching composition and application thereof
By optimizing the component ratio of the etching composition, the problems of side etching, undercutting, and non-uniformity in wet etching during chip bump manufacturing were solved, improving the selectivity of etching and the reliability and electrical performance of the chip.
Patent Information
- Application Number
- CN202511727755.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2020-09-29
- Publication Date
- 2026-03-03
AI Technical Summary
Existing wet etching compositions suffer from problems such as side etching, undercutting, aluminum electrode damage, uneven etching, and poor circuit morphology after etching during chip bump manufacturing, which affect chip reliability and electrical performance.
An etching composition is provided, comprising an oxidant, an inorganic acid, an organic acid, a chelating agent, and an ionic compound. By optimizing the component ratio, the etching rate and selectivity are controlled, side etching and undercutting are reduced, and etching uniformity and circuit morphology are improved.
It achieves low side etching amount, less undercut, good uniformity and stable etching effect, which improves the reliability and electrical performance of the chip.
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Figure CN121593073A_ABST
Abstract
Description
[0001] This application is a divisional application of Chinese application No. 202011053002.9, filed on September 29, 2020, entitled "An Etching Composition and Its Application". Technical Field
[0002] This invention relates to the field of chip processing technology, and in particular to an etching composition and its application. Background Technology
[0003] In integrated circuit manufacturing, extremely fine patterns are often defined on the wafer. These patterns are primarily formed using etching technology, which transfers the photoresist pattern created by microlithography onto the underlying material to form the complex architecture of the integrated circuit. After chip fabrication, specialized packaging plants create solder joints, or bumps, on the wafer to build interconnect media for the next interconnection step. This process is called advanced packaging technology. Similarly, packaging plants also use patterning processes to rearrange the interconnections or create bumps for the chip. After wafer fabrication, the first step is to use a magnetron sputtering machine to sputter a layer of titanium and a layer of copper across the entire wafer surface; this is known in the industry as the seed layer. The purpose of sputtering the titanium layer is to better bond it to the wafer, and the purpose of sputtering the copper layer is to provide a connection for the next step of copper plating. Before copper plating, photoresist is used for patterning so that the copper plating can fall on the openings. It becomes clear that the purpose of sputtering titanium and copper across the entire surface is to provide a medium for conducting current during electroplating, ensuring that the entire open area is plated with metal. A wafer typically contains anywhere from dozens to tens of thousands of chips. Due to the presence of the copper and titanium layers, all interconnect locations on the chips are interconnected, essentially in a short-circuit state. Therefore, the initially sputtered titanium and copper need to be removed by etching to ensure that the chip possesses specific electrical properties while the interconnect bumps are fabricated. Thus, etching technology plays a crucial role in semiconductor manufacturing and advanced packaging. Broadly speaking, etching technology encompasses techniques for uniformly removing material across an entire surface and selectively removing patterns. It can be broadly categorized into wet etching and dry etching. Currently, wet etching is widely used in chip bump manufacturing due to its advantages such as low cost, high reliability, high throughput, and superior etch selectivity.
[0004] Although wet etching is widely used in advanced packaging processes due to its unique advantages, the copper etching compositions in the industry still have the following drawbacks: 1. Due to isotropic etching, bumps are highly susceptible to lateral etching. 2. The seed layer is highly susceptible to undercut. 3. Aluminum electrode damage problem; 4. Incomplete and uneven etching caused by bubbles formed during the etching chemical reaction.
[0005] In addition to the issues mentioned above, wet etching also needs to consider the etching reaction rate and the erosion of the mask (i.e., the bumps mentioned above) by the etching composition.
[0006] While the manufacturing process for chip bumps is relatively mature, as the size of components in integrated circuits continues to shrink, the size of the bumps needs to be further reduced. Because chemical reactions are non-directional, wet etching is isotropic. In this case, when the etching solution performs vertical etching, lateral etching occurs simultaneously, leading to undercutting and distortion of the pattern linewidth. These issues significantly impact chip reliability.
[0007] Etching compositions often suffer from challenges due to the presence of multiple layers of different metals on the bumps, with the seed layer's metal differing from the bump's metal layers. This difference in etching rates across the multiple metal layers makes controlling the etching effect difficult. Furthermore, issues such as excessive critical dimension loss (CD loss) on the bumps and undercutting of the copper layer after etching are unavoidable. Currently, the primary oxidants in publicly available etching compositions are peroxides, typically persulfate and hydrogen peroxide. However, etching compositions using persulfate as an oxidant severely damage the nickel layer in the structural layers, while existing hydrogen peroxide-based oxidant etching compositions result in poor morphology of circuits or solder joints on the wafer after etching, affecting chip reliability.
[0008] The hydrogen peroxide etching composition described above requires an acidic environment to dissolve the copper. Among common inorganic acids, sulfuric acid severely corrodes the nickel in the structure, nitric acid severely corrodes tin or tin alloys and nickel, and hydrochloric acid and fluorine acid have strong penetrating power and will severely corrode the underlying aluminum metal of the chip. This corrosion will have a fatal impact on the reliability of the chip. Summary of the Invention
[0009] To address the problems existing in the prior art, this invention provides an etching composition. As described above, the copper and titanium layers need to be etched away during the bump fabrication process to provide chip interconnect capability while ensuring its electrical performance. The copper etching composition of this invention is a chemical solution used in wet etching to etch the copper layer in this process. Through the screening and research of additives, the etching composition can effectively control the morphology of the etched circuits or solder joints with low metal damage, thereby improving the reliability of the chip in the package interconnect.
[0010] The present invention provides an etching composition comprising: component A: 1-30 wt% oxidant, component B: 0.5-20 wt% inorganic acid, component C: 0-15 wt% organic acid, component D: 0.01-15 wt% chelating agent, component E: 0-0.1 wt% ionic compound and / or other inorganic acids other than the inorganic acid described in component B, and deionized water.
[0011] As a preferred technical solution, component A: the oxide is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate.
[0012] As a preferred technical solution, component B: the inorganic acid is selected from one or more of nitric acid, sulfuric acid, and phosphoric acid, or a mixture thereof.
[0013] As a preferred technical solution, the component C: organic acid is selected from one or more of the following: citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid.
[0014] As a preferred technical solution, the organic acid is one to five types.
[0015] As a preferred technical solution, the component D: chelating agent is selected from one or more of sodium gluconate, sodium citrate, and amino acids, or a mixture thereof.
[0016] As a preferred technical solution, the amino acid is selected from one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alanine, glycine, aspartic acid, glutamic acid, sarcosine, L-cysteine, lysine, cysteine, and methionine.
[0017] As a preferred technical solution, the ionic compounds in component E may be oxides and / or inorganic salts.
[0018] As a preferred technical solution, the inorganic acid in component E is selected from one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, and hydrofluoric acid.
[0019] The present invention also provides the application of the etching composition described above in the fabrication of a chip, the chip comprising bumps and a seed layer below the bumps; the bumps comprising an upper layer made of tin or a tin alloy and a lower layer made of nickel or a nickel-copper alloy.
[0020] This invention provides an etching composition that has the following advantages compared to the prior art: 1. Small side etching (CD loss); 2. The copper layer undercut is small; 3. It causes little or no damage to the substrate and does not affect the reliability of the chip. 4. Excellent etching uniformity and no etching residue; 5. The morphology of the circuits or solder joints on the wafer is good after etching; 6. The etching composition exhibits stable performance. Attached Figure Description
[0021] To further explain the beneficial effects of the etching composition and its application provided in this invention, corresponding drawings are provided. It should be noted that the drawings provided in this invention are only individual examples selected from all the drawings, and are not intended to limit the claims. All other corresponding spectra obtained through the drawings provided in this application should be considered to be within the scope of protection of this application.
[0022] Figure 1 This is a schematic diagram of the chip structure before bump etching.
[0023] Figure 2 This is a schematic diagram of the chip structure after bump etching. Detailed Implementation
[0024] The invention can be further understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. If the definitions of specific terms disclosed in the prior art are inconsistent with any definitions provided in this application, the definitions provided in this application shall prevail.
[0025] In this application, unless the context explicitly indicates otherwise, features not limited to the singular or plural form are intended to include features in the plural form as well. It should also be understood that, as used herein, the terms "prepared from" and "comprising," and "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, refer to the stated composition, step, method, article, or apparatus, but do not exclude the presence or addition of one or more other compositions, steps, methods, articles, or apparatuses. Furthermore, when describing embodiments of this application, the use of terms such as "preferred," "ideally," "more preferably," etc., refers to embodiments of the invention that, in certain circumstances, provide certain beneficial effects. However, other embodiments may also be preferred in the same or other circumstances. Moreover, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of the invention.
[0026] To address the problems existing in the prior art, the present invention provides an etching composition comprising: component A: 1-30 wt% oxidant, component B: 0.5-20 wt% inorganic acid, component C: 0-15 wt% organic acid, component D: 0.01-15 wt% chelating agent, component E: 0-0.1 wt% ionic compound and / or other inorganic acids except the inorganic acid described in component B, with the balance being deionized water.
[0027] As an example, the weight percentage of component A: oxidant in the etching composition can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 20%, 22%, 25%, 30%, etc.; as an example, the weight percentage of component B: inorganic acid in the etching composition can be 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc.; as an example, the weight percentage of component C: organic acid in the etching composition can be 0.1%, 0.5%, 1%, 2%, 3%, 5%, 8%, 1 ... 0%, 12%, 15%, etc.; as an example, the weight percentage of component D: chelating agent in the etching composition can be 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 8%, 10%, 12%, 15%, etc.; as an example, the weight percentage of component E: ionic compound and / or other inorganic acids besides the inorganic acid in component B in the etching composition can be 0.5%. ppm, 1 ppm, 1.2 ppm, 1.5ppm, 1.8 ppm, 2 ppm, 2.5 ppm, 2.8 ppm, 3 ppm, 3.2 ppm, 3.5 ppm, 3.8 ppm, 4 ppm, 4.2ppm, 4.5 ppm, 4.8 ppm, 5 ppm, 5.2 ppm, 5.5 ppm, 5.8 ppm, 6 ppm, 6.5 ppm, 7 ppm, 7.5ppm, 8 ppm, 8.5 ppm, 9 ppm, 9.5 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40ppm, 45 ppm, 50 ppm, 60 ppm, 65 ppm, 68 ppm, 70 ppm, 75 ppm, 80 ppm, 82 ppm, 85 ppm, 90ppm, 95 ppm, 100 ppm, etc.
[0028] In some preferred embodiments, the etching composition comprises: component A: 1-25 wt% oxidant, component B: 0.5-15 wt% inorganic acid, component C: 0-10 wt% organic acid, component D: 0.01-10 wt% chelating agent, component E: 0.1-100 ppm ionic compound and / or other inorganic acid besides the inorganic acid described in component B, with the balance being deionized water; more preferably, the etching composition comprises: component A: 1-20 wt% oxidant, component B: 0.5-15 wt% inorganic acid, component C: 0-5 wt% organic acid, component D: 0.1-10 wt% chelating agent, component E: 0.1-60 ppm ionic compound and / or other inorganic acid besides the inorganic acid described in component B, and deionized water.
[0029] In some preferred embodiments, the component A: oxide is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate; from the perspective of controllable etching process and improvement of over-etching, the oxide is further preferably hydrogen peroxide.
[0030] In some preferred embodiments, the hydrogen peroxide accounts for 1 to 15 wt% of the etching composition; more preferably, the hydrogen peroxide accounts for 1 to 10 wt% of the etching composition; and even more preferably, the hydrogen peroxide accounts for 2 to 10 wt% of the etching composition.
[0031] In some preferred embodiments, component B: inorganic acid does not contain halogen acid.
[0032] In some preferred embodiments, component B: the inorganic acid is selected from one or more of nitric acid, sulfuric acid, and phosphoric acid; from the perspective of regulating the etching reaction rate, component B: the inorganic acid is further preferably phosphoric acid. The inventors discovered in their research that inorganic acids can dissolve copper and have a positive effect on the etching reaction rate, but when the amount of inorganic acid exceeds 20 wt%, it will cause material surplus and increase the cost burden.
[0033] In some embodiments, component C: organic acid is selected from one or more of citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid; preferably, component C: organic acid is selected from citric acid, acetic acid, tartaric acid, malic acid, butyric acid, oxalic acid, malonic acid, succinic acid, glycolic acid, and propionic acid. The component C is a mixture of one or more of the following: acetic acid, lactic acid, maleic acid, benzoic acid, and salicylic acid; more preferably, the component C: organic acid is selected from one or more of the following: acetic acid, citric acid, tartaric acid, malic acid, oxalic acid, formic acid, acrylic acid, lactic acid, maleic acid, benzoic acid, and salicylic acid; even further, the component C: organic acid is selected from one or more of the following: acetic acid, citric acid, tartaric acid, malic acid, oxalic acid, formic acid, acrylic acid, lactic acid, maleic acid, benzoic acid, and salicylic acid.
[0034] In some embodiments, the number of organic acids is one to five; preferably, the number of organic acids is at least two, at least three, or at least four; more preferably, the number of organic acids is one, two, three, or four. The inventors discovered in their research that when the number of organic acids exceeds five, the etching solution affects the etching rate and etching uniformity of the metal.
[0035] To ensure the safety of the etching process and address the issue of copper residue, the etching time is typically increased by 15% on top of the standard process allowance, and in some cases, even by 100%. This leads to uneven etching of the copper metal, with the uniformity of the etched metal generally below 15%. To ensure etching uniformity, maintain process safety, and resolve the issue of metal residue, the inventors of this application have discovered through extensive experimentation that adding an organic acid, comprising no more than 15% by weight of the etching composition, can effectively improve the uniformity of copper etching and reduce metal residue, while ensuring the safety of the etching process. However, the inventors also found that when the organic acid content exceeds 10%, it significantly inhibits the copper etching rate. Therefore, the organic acid content in the etching composition of this invention is preferably no more than 10 wt%. To ensure the etching rate meets requirements, maintains etching uniformity, resolves the metal residue issue, and ensures etching safety, the organic acid's weight percentage in the etching process is preferably 0-10%, more preferably 0.1-5%.
[0036] In some preferred embodiments, the component D: chelating agent is selected from one or more of sodium gluconate, sodium citrate, and amino acids; more preferably, the component D: chelating agent is an amino acid.
[0037] In some preferred embodiments, the amino acid is selected from one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alanine, glycine, aspartic acid, glutamic acid, sarcosine, L-cysteine, lysine, cysteine, and methionine; more preferably, the amino acid is selected from one or more of alanine, glycine, lysine, cysteine, and methionine; even further, the amino acid is selected from one or more of lysine, cysteine, and methionine. During the research and development process, the inventors discovered that adding the amino acid to the etching composition can reduce the lateral etching amount (CD) of the bumps and seed layer. Through extensive practical experience, the inventors also found that when the weight percentage of the chelating agent in the system is in the range of 0.1% to 8%, the lateral etching amount of the etched copper bumps decreases with increasing chelating agent content; however, when the weight percentage of the chelating agent in the etching composition exceeds 8%, it will significantly reduce the copper etching uniformity and greatly increase the occurrence of copper residue. During careful verification, the inventors discovered that when the content of the chelating agent approached 2wt%, the positive effect of the chelating agent tended to stabilize, that is, the improvement on the lateral corrosion amount CD reached the optimal value.
[0038] In some preferred embodiments, when component E is an ionic compound, the ionic compound is an oxide and / or an inorganic salt.
[0039] In some preferred embodiments, the oxide is a basic oxide and / or an amphoteric oxide; more preferably, the basic oxide is selected from one or more of sodium oxide, calcium oxide, and magnesium oxide, and the amphoteric oxide is zinc oxide and / or manganese oxide.
[0040] In some preferred embodiments, the inorganic salt is preferably a halide salt, which is selected from one or more of copper chloride, ferric chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper bromide, ferric bromide, sodium bromide, ammonium bromide, copper iodide, ferric iodide, sodium iodide, ammonium iodide, copper fluoride, ferric fluoride, sodium fluoride, and ammonium fluoride; more preferably, the halide salt is selected from one or more of copper chloride, ferric chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper fluoride, ferric fluoride, sodium fluoride, and ammonium fluoride.
[0041] In some preferred embodiments, when component E is an inorganic acid, the inorganic acid is preferably another inorganic acid besides the inorganic acid in component B, more preferably a halogen acid, the halogen acid being selected from one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, and hydrofluoric acid; more preferably, the halogen acid is hydrochloric acid and / or hydrofluoric acid; and even more preferably, the halogen acid is hydrochloric acid.
[0042] In some preferred embodiments, the inorganic salt accounts for 0.1 to 100 ppm by weight in the etching composition, and when component E is a halogen acid, its weight percentage in the etching composition is 0.01 to 5 ppm. The inventors discovered during their research that component E can effectively improve the undercut problem of copper; below 100 ppm, the undercut increases with increasing concentration of component E.
[0043] In some preferred embodiments, component E is a mixture of at least one halide salt and at least one halogen acid, wherein the halide salt is selected from one or more of copper chloride, ferric chloride, sodium chloride, ammonium chloride, potassium chloride, calcium chloride, copper fluoride, ferric fluoride, sodium fluoride, and ammonium fluoride, and the halogen acid is hydrochloric acid and / or hydrofluoric acid.
[0044] In some preferred embodiments, the component E is present in the etching composition at a weight ratio of 0.1 to 80 ppm, and is a mixture of a halide salt and a halogen acid, wherein the halide salt is present in the etching composition at a weight ratio of 0.1 to 50 ppm, and the halogen acid is present in the etching composition at a weight ratio of 0.1 to 30 ppm. As an example, the weight percentage of the halide salt in the etching composition can be 0.1 ppm, 0.3 ppm, 0.5 ppm, 0.8 ppm, 1 ppm, 1.2 ppm, 1.5 ppm, 2 ppm, 2.5 ppm, 3 ppm, 3.5 ppm, 4 ppm, 4.5 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 50 ppm, etc.; as an example, the weight percentage of the halogen acid in the etching composition can be 0.1 ppm, 0.3 ppm, 0.5 ppm, 0.8 ppm, 1 ppm, 1.2 ppm, 1.5 ppm, 2 ppm, 2.5 ppm, 3 ppm, 3.5 ppm, 4 ppm, 4.5 ppm, 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, etc. ppm, 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, etc.
[0045] In this invention, component A (oxide) and component B (inorganic acid) are the main components controlling the metal etching rate. The utilization rate is highest when their weight ratio is between 1:2 and 2:1. Otherwise, the larger amount of the latter will be excessive, which, although not obviously negative, can be considered an ineffective addition, increasing costs. The preferred concentration is defined based on the bump fabrication process time; excessively high or low metal etching rates will cause difficulties in process control. Empirically, a metal etching rate of 35–300 Å / s is optimal. The addition of component C (organic acid) ensures the uniformity and safety of etching and solves the problem of copper residue, while component D (chelating agent) can adjust the ion concentration in the system and reduce the lateral corrosion of bumps and seed layers. The inventors unexpectedly discovered in practice that when component E contains both halide salts and halogen acids, the etching composition not only effectively improves the undercut problem but also effectively improves the morphology of the etched metal, effectively improves the etching uniformity, and effectively improves the stability of the etching composition.
[0046] The method for preparing the etching composition in this invention can be any one known to those skilled in the art, such as physical blending.
[0047] The present invention also provides applications of the above-described etching composition for manufacturing display devices; further, the etching composition is used to create bumps on a chip.
[0048] The chip of this invention includes bumps and a seed layer below the bumps; the bumps comprise an upper layer made of tin or a tin alloy and a lower layer made of nickel or a nickel-copper alloy. The type of tin alloy used in this application is not specifically limited, but generally refers to an alloy of tin with metals such as copper, silver, and lead. In some embodiments, an electroplated layer is further included between the bumps and the seed layer.
[0049] like Figure 1 The diagram shows a schematic of a chip bump, wherein the chip includes bumps and a seed layer below the bumps; the bumps include an upper layer made of tin-silver alloy and a lower layer made of nickel; the seed layer includes a copper seed layer and a titanium seed layer from top to bottom; and an electroplated copper layer is located between the bumps and the seed layer.
[0050] The structure described here, comprising an upper layer of tin or a tin alloy and a lower layer of nickel, or a lower layer of nickel and copper, is a commonly used metal bump material in advanced packaging processes. Its advantages include stable performance and low cost. Nickel serves as a barrier layer connecting electroplated copper or a copper seed layer, providing conductivity while preventing the migration of copper and tin components, thus ensuring the reliability of the bump. The necessity of copper plating may be considered for different types of chips depending on design requirements. Tin alloys and tin are used as interconnect materials during further chip packaging, selected based on the electrical performance requirements of the design.
[0051] Example The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described. Unless otherwise specified, all raw materials used in the present invention are commercially available.
[0052] Performance parameter test indicators of the etching composition of the present invention: 1. Side etching amount CD loss, such as Figures 1-2 As shown, the amount of horizontal shrinkage of electroplated copper before and after copper etching is called the side etching loss (CD loss), with the unit being μm. After etching, the electroplated copper and the copper seed layer should be as flush as possible with the Ni or Sn / Ag layer, with no shrinkage. Therefore, a low CD is a performance advantage, and applications generally require less than 1 μm.
[0053] 2. Undercut, such as Figures 1-2 As shown, on one side of the bump, the amount of shrinkage in the horizontal direction of the etched copper seed layer relative to the electroplated copper or nickel layer (in the absence of an electroplated layer) is called the undercut, measured in μm. After etching, the electroplated copper and the copper seed layer should be as flush as possible with the Ni or Sn / Ag layer without shrinkage. Therefore, a low undercut is a performance advantage, and applications generally require less than 1 μm.
[0054] 3. Uniformity, expressed as a percentage, involves collecting a certain number of points on the wafer (this invention uses an 8-inch wafer and a method of uniformly collecting 24 points) to measure the copper etching thickness X. Uniformity = (X...) max -X min ) / (2X avg ), where X max X min X avg These represent the maximum, minimum, and average values of the etching thickness, respectively. Low uniformity is a desirable value, and general applications require it to be less than 5%.
[0055] 4. Metal corrosion rate, based on the damage rate of tin or tin alloy, nickel, and aluminum, in Å / s. The lowest corrosion rate is the optimal value for performance. Generally, applications require nickel damage to be less than 20 Å / s, tin or tin alloy damage to be less than 0.1 Å / s, and aluminum damage to be less than 20 Å / s.
[0056] Examples 1-12 and Comparative Examples 1-3 all provide an etching composition, and the components in each example are shown in Table 1. The etching composition is prepared by physical blending.
[0057]
[0058]
[0059] Performance test results The etching compositions obtained in Examples 1-12 and Comparative Examples 1-3 were subjected to performance tests, including side etching loss (CD loss), undercut, uniformity, and metal corrosion rate. The test results are shown in Table 2.
[0060] To ensure the parallel implementation of the implementation scheme and the control scheme, the experimental process used, for example... Figure 1 The wafer with the structure shown (the Cu seed layer thickness of the experimental wafer was 3000 Å) was subjected to an immersion experiment in a solution. The experimental temperature was kept constant at 25℃.
[0061] Furthermore, while ensuring the same experimental method is used, it should be noted that the influencing factors for the values of CD and undercut are the formulation composition and overcut amount. Here, following the convention of formula usage, the overcut amount is 100% as the experimental background condition. The overcut amount mentioned in this application is the experimental background condition, expressed as a percentage. Overcut amount = (t-t0) / t0, where t0 is the time it takes for the copper surface to be completely etched clean, and t is the actual etching time.
[0062]
[0063] By comparing the data from comparative examples and embodiments, it can be seen that the etching composition of the present invention has significant improvements in side etching amount, undercut amount and uniformity. At the same time, it also has a low metal corrosion rate. When applied to substrate etching, it causes virtually no damage to the substrate, greatly improving the reliability of the chip.
[0064] The foregoing examples are merely illustrative, used to explain some features of the method described in this invention. The appended claims are intended to claim the broadest possible scope, and the embodiments presented herein are merely illustrative of selected implementations based on combinations of all possible embodiments. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the invention. Some numerical ranges used in the claims also include sub-ranges within them, and variations within these ranges should also be interpreted as being covered by the appended claims where possible.
Claims
1. An etching composition, characterized in that, The etching composition comprises: component A: 2-10 wt% oxidant, component B: 0.5-20 wt% inorganic acid, component C: 0.1-5 wt% organic acid, component D: 0.1-8 wt% chelating agent, component E: 0-0.1 wt% ionic compound and / or other inorganic acids except the inorganic acid described in component B, and deionized water; Component A: The oxidant is selected from at least one of hydrogen peroxide, potassium persulfate, and sodium persulfate; Component B: Inorganic acid selected from one or more of nitric acid, sulfuric acid, and phosphoric acid, or a mixture thereof.
2. The etching composition according to claim 1, characterized in that, Component C: Organic acid is selected from one or more of the following: citric acid, acetic acid, tartaric acid, malic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, malonic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, acrylic acid, methacrylic acid, lactic acid, gluconic acid, maleic acid, benzoic acid, and salicylic acid.
3. The etching composition as described in claim 2, characterized in that, The organic acids are of one to five types.
4. The etching composition according to claim 1, characterized in that, Component D: The chelating agent is selected from one or more of sodium gluconate, sodium citrate, and amino acids, or a mixture thereof.
5. The etching composition as claimed in claim 4, characterized in that, The amino acid is selected from one or more of the following: ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alanine, glycine, aspartic acid, glutamic acid, sarcosine, L-cysteine, lysine, cysteine, and methionine.
6. The etching composition according to any one of claims 1 to 5, characterized in that, The ionic compound is an oxide and / or an inorganic salt.
7. The etching composition according to any one of claims 1 to 5, characterized in that, The inorganic acid in component E is selected from one or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, and hydrofluoric acid, or a mixture thereof.
8. The application of the etching composition as described in claims 1-7 in chip fabrication, characterized in that, The chip includes bumps and a seed layer below the bumps; the bumps include an upper layer made of tin or a tin alloy and a lower layer made of nickel or a nickel-copper alloy.