Tungsten / titanium nitride etching solution avoiding intermetallic electrochemical corrosion effect

Abstract

The present application relates to a kind of tungsten titanium nitride etching solution of avoiding intermetallic electrochemical corrosion effect, the etching solution includes the following components by mass percentage: 10%-30% hydrogen peroxide, 1-5% alkali, 1%-5% surfactant, 0.1%-2% electrochemical corrosion inhibitor, the rest is deionized water.Electrochemical corrosion inhibitor can significantly reduce the electrochemical corrosion reaction potential between tungsten layer and titanium / titanium nitride layer, inhibit the corrosion current between tungsten layer and titanium / titanium nitride layer, make the electrochemical corrosion between two metal layers weaken.Simultaneously surfactant can adjust the infiltration, contact between etching solution and different film layers.Ensure that each film layer is etched completely, avoid the phenomenon such as metal tailing, affect subsequent process.In the present application, the tungsten / titanium nitride etching solution of avoiding intermetallic electrochemical corrosion effect can significantly reduce the electrochemical corrosion effect between metal tungsten layer and titanium / titanium nitride layer compared with ordinary etching solution, while also can maintain stable etching rate and life.

Description

Technical Field

[0001] This invention belongs to the cross-technical field of metal wet etching and IGBT chip technology, specifically relating to a tungsten / titanium nitride etching solution that avoids the electrochemical corrosion effect between metals and its application method. Background Technology

[0002] In the manufacturing of automotive-grade chips, IGBT chips are commonly used in voltage conversion scenarios. The contacts and interconnects in IGBTs are typically constructed using a multilayer structure of metals such as tungsten, titanium, and copper, or their alloys. This structure is highly susceptible to electrochemical corrosion due to the galvanic effect; the greater the difference in activity between the metals, the more severe the electrochemical corrosion effect. Therefore, during the etching process of each metal layer, different etching rates are common, resulting in uneven lateral etching and etching cone angles. In tungsten / titanium nitride multilayer etching, tungsten acts as the anode, losing electrons while the titanium / titanium nitride layer gains electrons. The electrochemical corrosion of the tungsten layer, combined with its inherently high chemical activity, makes its etching rate significantly higher than that of the titanium / titanium nitride layer. Therefore, developing a tungsten / titanium nitride etching solution that avoids the intermetallic electrochemical corrosion effect is crucial. Summary of the Invention

[0003] The purpose of this invention is to provide a tungsten / titanium nitride etching solution and its application method that avoids the electrochemical corrosion effect between metals.

[0004] To achieve this objective, the present invention adopts the following technical solution: A tungsten / titanium nitride etching solution that avoids the electrochemical corrosion effect between metals, the etching solution comprising the following components by mass percentage: 10%~30% hydrogen peroxide, 1%~5% alkali, 1%~5% surfactant, 0.1%~2% electrochemical corrosion inhibitor, and the balance being deionized water.

[0005] Preferably, the etching solution further includes the following components by mass percentage: 0.1%-1% metal ion masking agent.

[0006] Preferably, the alkali is potassium hydroxide, ammonia, or tetramethylammonium hydroxide or a combination thereof.

[0007] Preferably, the surfactant is acetamide, isobutyramide, chloroacetamide, or N-vinylacetamide or a combination thereof.

[0008] Preferably, the electrochemical corrosion inhibitor is dodecylphosphonic acid, phenylphosphonic acid, 1,4-butanediphosphonic acid, or 4-aminobutylphosphonic acid, or a combination thereof.

[0009] More preferably, the metal ion masking agent is cyclobenzafine hydrochloride, chlormethazine, bezafibrate, or cyclobenzafine or a combination thereof. Compared with the prior art, the present invention has the following beneficial effects: The advantages and beneficial effects of this invention are as follows: The etching solution is composed of hydrogen peroxide, inorganic alkali, metal ion masking agent, electrochemical corrosion inhibitor, surfactant, and deionized water. The alkali is at least one of potassium hydroxide, ammonia, and tetramethylammonium hydroxide, used to adjust the pH value of the etching solution to stabilize the etching rate; hydrogen peroxide acts as an oxidant; the metal ion masking agent can complex with tungsten ions, inhibiting tungsten oxidation, reducing the etching rate of the tungsten by the etching solution, and improving the etching selectivity. The electrochemical corrosion inhibitor can significantly reduce the electrochemical corrosion reaction potential between the tungsten layer and the titanium / titanium nitride layer, inhibiting the corrosion current between the tungsten layer and the titanium / titanium nitride layer, thus weakening the electrochemical corrosion between the two metal layers. Simultaneously, the surfactant can adjust the wetting and contact between the etching solution and different film layers, ensuring that each film layer is completely etched and avoiding phenomena such as metal tailing, which would affect subsequent processes. The tungsten / titanium nitride etching solution of this invention can avoid the electrochemical corrosion effect between metals. Compared with ordinary etching solutions, it can significantly reduce the electrochemical corrosion effect between the tungsten layer and the titanium / titanium nitride layer, while maintaining a stable etching rate and lifespan. Detailed Implementation

[0010] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] The etching temperature and etching time were 60℃ and 5min, respectively.

[0012] The etching solution was prepared in a beaker according to its composition. 50g of the etching solution, after being ultrasonically stirred, was placed in a 60℃ constant temperature water bath. After the etching solution temperature reached 60℃ and stabilized for a period of time, the tungsten and titanium nitride monolayer metal films were cut into 1.6cm×1.6cm pieces using a knife, rinsed with ultrapure water, and purged with nitrogen gas. The film thickness of the tungsten and titanium nitride sheets before etching was measured using a four-probe thickness gauge. Then, the tungsten and titanium nitride sheets were fixed back to back (with the silicon substrate layer attached), and the working electrodes of the electrochemical workstation were connected to the tungsten and titanium nitride metal layers respectively to measure the corrosion current Icorr flowing between the tungsten and titanium nitride during the etching process. During etching, the test piece was fixed with a fixture and suspended in a continuously circulating etching solution at 60°C. After etching for 5 minutes, the tungsten and titanium nitride sheets were removed, rinsed with ultrapure water, purged with nitrogen, and the film thickness of the tungsten and titanium nitride after etching was measured with a four-probe thickness gauge. The corrosion rate of the metal by the etching solution was obtained by the difference in film thickness before and after etching. The intensity of electrochemical corrosion during this etching was characterized by the corrosion current Icorr measured by the potentiostat of the electrochemical workstation.

[0013] Example 1 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% potassium hydroxide, balance ultrapure water.

[0014] Example 2 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, balance ultrapure water.

[0015] Example 3 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% tetramethylammonium hydroxide, balance ultrapure water.

[0016] Example 4 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% acetamide, balance ultrapure water.

[0017] Example 5 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, balance ultrapure water.

[0018] Example 6 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% chloroacetamide, balance ultrapure water.

[0019] Example 7 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% N-vinylacetamide, balance ultrapure water.

[0020] Example 8 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline hydrochloride, balance ultrapure water.

[0021] Example 9 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% chlormethazine, balance ultrapure water.

[0022] Example 10 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% bezafibrate, balance ultrapure water.

[0023] Example 11 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline, balance ultrapure water.

[0024] Example 12 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0025] Example 13 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% phenylphosphine, balance ultrapure water.

[0026] Example 14 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0027] Example 15 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0028] Example 16 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline hydrochloride, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0029] Example 17 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline hydrochloride, 0.5wt% phenylphosphonic acid, balance ultrapure water.

[0030] Example 18 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzahrin hydrochloride, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0031] Example 19 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline hydrochloride, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0032] Example 20 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% chlormethazine, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0033] Example 21 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% chlormethazine, 0.5wt% phenylphosphine, balance ultrapure water.

[0034] Example 22 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% chlormethazine, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0035] Example 23 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% chlormethazine, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0036] Example 24 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% bezafibrate, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0037] Example 25 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% bezafibrate, 0.5wt% phenylphosphine, balance ultrapure water.

[0038] Example 26 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% bezafibrate, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0039] Example 27 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% bezafibrate, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0040] Example 28 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0041] Example 29 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline, 0.5wt% phenylphosphonic acid, balance ultrapure water.

[0042] Example 30 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0043] Example 31 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 1wt% isobutyramide, 0.5wt% cyclobenzaline, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0044] Comparative Example 1 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% cyclobenzaline hydrochloride, balance ultrapure water.

[0045] Comparative Example 2 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% chlormethazine, balance ultrapure water.

[0046] Comparative Example 3 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% benzalkonium chloride, balance ultrapure water.

[0047] Comparative Example 4 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% cyclobenzaline, balance ultrapure water.

[0048] Comparative Example 5 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% dodecylphosphonic acid, balance ultrapure water.

[0049] Comparative Example 6 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% phenylphosphine, balance ultrapure water.

[0050] Comparative Example 7 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0051] Comparative Example 8 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% 4-aminobutylphosphonic acid, balance ultrapure water.

[0052] Comparative Example 9 A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion effects comprises the following: 20wt% hydrogen peroxide, 5wt% ammonia, 0.5wt% chlormethazine, 0.5wt% 1,4-butanediphosphonic acid, balance ultrapure water.

[0053] Detection method: With a fixed etching time of tungsten (Å / min), the film thickness of the tungsten sheet before and after etching is measured using a four-probe thickness gauge, thus obtaining the tungsten etching rate. With a fixed etching time of titanium nitride (Å / min), the film thickness of the titanium nitride sheet before and after etching is measured using a four-probe thickness gauge, thus obtaining the etching rate of titanium nitride.

[0054] Corrosion current Icorr (A): During the etching process, the corrosion current Icorr flowing between tungsten and titanium nitride is directly measured using the working electrode of an electrochemical workstation.

[0055] The experimental results are shown in Table 1: In Examples 1-3, because no components other than oxidant, alkali, and ultrapure water were added, the etching rate of tungsten in all three formulations was above 300 Å / min, with a relatively large amount of metal residue. Simultaneously, the corrosion current measured by the electrochemical workstation was greater than 3 × 10⁻⁶. -6 A.

[0056] In Examples 4-7, the addition of surfactants improved the problem of metal residue during the etching process. In Examples 5 and 6, trace amounts of metal remained, but the addition of surfactants also slightly increased the etching rate of tungsten.

[0057] In Examples 8-15, single-component metal ion masking agents or electrochemical corrosion inhibitors were added to formulations based on hydrogen peroxide, alkali, and surfactants. In Examples 8-11, the addition of different types of metal ion masking agents showed varying abilities to complex with tungsten ions, resulting in a decrease in the tungsten etching rate, all below 300 Å / min. However, since the corrosion current was not yet suppressed, the overall inhibitory effect of the etching solution on tungsten was still insufficient. In Examples 12-15, among the different electrochemical corrosion inhibitors added, only Example 14 significantly reduced the corrosion current, lowering Icurr below 1 × 10⁻⁶. -6 A. This indicates that the presence of electrochemical corrosion inhibitors plays a crucial role in suppressing tungsten etching.

[0058] Examples 16-31 involved cross-combinations of the metal ion masking agents and electrochemical corrosion inhibitors used in Examples 8-15, with Example 22 showing the most significant effect. Under the combined action of the metal ion masking agent and the electrochemical corrosion inhibitor, the tungsten etching rate was 2.7 Å / min and the corrosion current was 0.2 × 10⁻⁶. -7 A. The selectivity ratio of tungsten / titanium nitride reaches 1:5.74. This indicates that when both the metal ion masking agent and the electrochemical corrosion inhibitor are present in the formulation, the complexing effect of the formulation components on tungsten is consistent with their inhibitory effect on corrosion current, further reducing the etching rate of tungsten by the etching solution and further improving the selectivity ratio of tungsten / titanium nitride. When both the metal ion masking agent and the electrochemical corrosion inhibitor in the etching solution formulation are preferred components, the etching solution can possess the characteristic of avoiding intermetallic electrochemical corrosion effects. Table 1

[0059] The technical solutions of the present invention have been explained through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by those skilled in the art based on the present invention, or equivalent substitutions for the materials selected in the present invention, fall within the scope of patent protection.

Claims

1. A tungsten / titanium nitride etching solution that avoids intermetallic electrochemical corrosion, characterized in that, The etching solution comprises the following components by mass percentage: 10%~30% hydrogen peroxide, 1%~5% alkali, 1%~5% surfactant, 0.1%~2% electrochemical corrosion inhibitor, 0.1%~1% metal ion masking agent, and the balance being deionized water; Electrochemical corrosion inhibitors are dodecylphosphonic acid, phenylphosphonic acid, 1,4-butanediphosphonic acid or 4-aminobutylphosphonic acid or combinations thereof; The metal ion masking agent is cyclobenzafine hydrochloride, chlormethazine, bezafibrate, or cyclobenzafine or a combination thereof; The base is potassium hydroxide, ammonia, or tetramethylammonium hydroxide or a combination thereof; The surfactant is acetamide, isobutyramide, chloroacetamide, or N-vinylacetamide or a combination thereof.

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