Etching composition

Abstract

To provide etching compositions that are useful, e.g., for selectively removing tungsten (W) and / or titanium nitride (TiN) from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.SOLUTION: An etching composition comprises: phosphoric acid in an amount of about 65 wt.% to about 90 wt.% of the composition; acetic acid in an amount of about 0.01 wt.% to about 4 wt.% of the composition; nitric acid in an amount of about 0.01 wt.% to about 5 wt.% of the composition; and water.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Application No. 62 / 730,043, filed on 12 September 2018, the contents of which are incorporated herein by reference in their entirety. Areas of disclosure This disclosure relates to compositions and processes for selectively etching aluminum oxide (AlOx such as Al2O3), tungsten (W), and / or titanium nitride (TiN) in the presence of other exposed or underlying materials such as metal conductors, barrier materials, and insulating materials (e.g., high-k dielectric materials). [Background technology]

[0002] The semiconductor industry is rapidly reducing the dimensions and increasing the density of electronic circuits and components in ultra-small electronic devices, silicon chips, liquid crystal displays, MEMS (Micro Electro Mechanical Systems), printed circuit boards, NAND flash memory, etc. The integrated circuits within them are constantly being stacked with smaller feature sizes, by continuously reducing the thickness of the insulating layers between each circuit layer. As the feature size shrinks, the patterns become smaller, and the device performance parameters become more stringent and robust. As a result, various problems that were previously tolerated are no longer tolerable or have become more problematic due to the smaller feature size.

[0003] In the production of advanced integrated circuits, both high-k and low-k insulators, as well as various barrier layer materials, have been employed to minimize problems associated with higher density and optimize performance.

[0004] Aluminum oxide (AlOx, such as Al2O3), tungsten (W), and titanium nitride (TiN) are used in semiconductor devices, liquid crystal displays, NAND flash memory, MEMS (Micro Electro Mechanical Systems), and printed circuit boards, and are utilized as ground layers or cap layers for precious metals. In semiconductor devices, W and TiN can be used as barrier metals, hard masks, or gate materials, while AlOx can be used as a dielectric material.

[0005] In constructing devices for these applications, AlOx, W, and TiN often need to be etched in the same etching process. In various types of AlOx, W, and TiN applications and device environments, other layers are in contact with or exposed simultaneously with the etching of these materials. Highly selective etching of AlOx, W, and TiN in the presence of these other materials (e.g., metallic conductors, dielectrics, and hard marks) is necessary for device yield and long lifespan. The etching process for AlOx, W, and TiN may be a plasma etching process. However, using a plasma etching process on AlOx, W, and TiN layers can damage either or both the gate insulating layer and the semiconductor substrate. In addition, the etching process can remove a portion of the semiconductor substrate by etching the gate insulating layer exposed by the gate electrode. The electrical properties of the transistor may be negatively affected. Additional protective device manufacturing processes can be used to avoid such etching damage, but this incurs considerable cost.

[0006] Wet etching methods for AlOx, W, and TiN are known. Such methods may involve the use of etching agents in combination with other reagents. However, the selectivity for silicon-based dielectrics and other high-k dielectric materials (HfOx) is insufficient, and other exposed metals within the device may also be corroded or etched.

[0007] Therefore, during the etching process, an etching solution is needed that has a high etching rate for AlOx, W, or TiN, but a low etching and corrosion rate for other semiconductor materials that are exposed or in contact with AlOx, W, or TiN. [Overview of the project]

[0008] This disclosure relates to compositions and processes for selectively etching AlOx, W, and / or TiN against metal conductor layers, hard mask layers, and low-k dielectric layers present in semiconductor devices. More specifically, this disclosure relates to compositions and processes for selectively etching AlOx against W and / or TiN, and / or for selectively etching W and / or TiN against specific high-k dielectric layers and / or low-k dielectric layers.

[0009] In one embodiment, the present disclosure features an etching composition comprising: a) phosphoric acid in an amount of about 65% to about 90% by weight of the composition; b) acetic acid in an amount of about 0.01% to about 4% by weight of the composition; c) nitric acid in an amount of about 0.01% to about 5% by weight of the composition; and d) water.

[0010] In another embodiment, the present disclosure features a method comprising contacting a semiconductor substrate containing AlOx, W, and / or TiN with an etching composition described herein to remove AlOx, W, and / or TiN.

[0011] In yet another embodiment, the disclosure features an article formed by the method described above, which is a semiconductor device (e.g., an integrated circuit). [Modes for carrying out the invention]

[0012] As defined herein, unless otherwise specified, all percentages expressed should be understood as weight percentages relative to the total weight of the composition. Unless otherwise specified, ambient temperature is defined as approximately 16 to approximately 27°C.

[0013] Generally, the present disclosure features etching compositions (e.g., etching compositions for selectively removing tungsten and / or titanium nitride) comprising (a) phosphoric acid in an amount of about 65% to about 90% by weight of the composition, (b) acetic acid in an amount of about 0.01% to about 4% by weight of the composition, (c) nitric acid in an amount of about 0.01% to about 5% by weight of the composition, and (d) water (e.g., substantially comprising, or consisting of ). In some embodiments, the etching composition may consist of phosphoric acid, acetic acid, and nitric acid, or phosphoric acid, acetic acid, nitric acid, and water.

[0014] In some embodiments, phosphoric acid is present in an amount ranging from at least about 65% by weight (e.g., at least about 66% by weight, at least about 67% by weight, at least about 68% by weight, at least about 69% by weight, at least about 70% by weight, at least about 71% by weight, at least about 72% by weight, at least about 73% by weight, at least about 74% by weight, at least about 75% by weight, at least about 80% by weight, or at least about 85% by weight) to a maximum of about 90% by weight (e.g., up to about 89% by weight, up to about 88% by weight, up to about 87% by weight, up to about 86% by weight, up to about 85% by weight, up to about 84% by weight, up to about 83% by weight, up to about 82% by weight, up to about 81% by weight, up to about 80% by weight, up to about 79% by weight, up to about 78% by weight, up to about 77% by weight, up to about 76% by weight, or up to about 75% by weight) of the etching composition of the Disclosure. While we do not wish to be bound by theory, it is thought that phosphoric acid can facilitate and enhance the removal of AlOx, W, and / or TiN from semiconductor substrates during the etching process.

[0015] In some embodiments, acetic acid is present in an amount of at least about 0.01% by weight (e.g., at least about 0.05% by weight, at least about 0.1% by weight, at least about 0.2% by weight, at least about 0.3% by weight, at least about 0.4% by weight, at least about 0.5% by weight, at least about 1% by weight, at least about 1.5% by weight, at least about 2% by weight, at least about 2.2% by weight, at least about 2.4% by weight, at least about 2.5% by weight, at least about 2.6% by weight, at least about 2.8% by weight, less than It is present in amounts ranging from at least about 3 wt%, and at least about 3.2 wt%, to a maximum of about 4 wt% (e.g., up to about 3.8 wt%, up to about 3.6 wt%, up to about 3.5 wt%, up to about 3.4 wt%, up to about 3.2 wt%, up to about 3 wt%, up to about 2.8 wt%, up to about 2.6 wt%, up to about 2.5 wt%, up to about 2 wt%, up to about 1.5 wt%, up to about 1 wt%, up to about 0.9 wt%, up to about 0.8 wt%, up to about 0.7 wt%, up to about 0.6 wt%, or up to about 0.5 wt%). While we do not wish to be bound by theory, it is thought that acetic acid can control the etching selectivity of AlOx, TiN, and W to other materials exposed during the etching process (e.g., high-k or low-k dielectric materials).

[0016] In some embodiments, nitric acid is present in an amount of at least about 0.01% by weight of the etching composition of the Disclosure (e.g., at least about 0.02% by weight, at least about 0.04% by weight, at least about 0.05% by weight, at least about 0.06% by weight, at least about 0.08% by weight, at least about 0.1% by weight, at least about 0.2% by weight, at least about 0.3% by weight, at least about 0.4% by weight, at least about 0.5% by weight, at least about 1% by weight, at least about 1.5% by weight, at least about It is present in amounts ranging from 2 wt%, at least about 2.5 wt%, or at least about 3 wt%) to up to about 5 wt% (e.g., up to about 4.5 wt%, up to about 4 wt%, up to about 3.5 wt%, up to about 3 wt%, up to about 2.5 wt%, up to about 2 wt%, up to about 1.6 wt%, up to about 1.5 wt%, up to about 1 wt%, up to about 0.9 wt%, up to about 0.8 wt%, up to about 0.7 wt%, up to about 0.6 wt%, up to about 0.5 wt%, or up to about 0.1 wt%). While we do not wish to be bound by theory, it is thought that nitric acid can act as an oxidizing agent for metals such as TiN and W, and can control the etching selectivity of TiN and W to other materials exposed during the etching process (e.g., high-k or low-k dielectric materials). Furthermore, although we do not wish to be bound by theory, it is thought that by controlling the amounts of acetic acid and nitric acid in the etching composition to a specific ratio (e.g., about 1.5:1 to 1:1.5), the W etching rate and the TiN etching rate can be adjusted to a specific ratio (e.g., about 3:1 to about 4:1). Such etching compositions may be suitable for use in connection with semiconductor substrates containing a W layer having a relatively large thickness and a TiN layer having a relatively small thickness.

[0017] In some embodiments, water is present in an amount of at least about 10 wt% (e.g., at least about 12 wt%, at least about 14 wt%, at least about 15 wt%, at least about 16 wt%, at least about 18 wt%, at least about 20 wt%, at least about 21 wt%, at least about 22 wt%, at least about 23 wt%, or at least about 24 wt%) to a maximum of about 30 wt% (e.g., a maximum of about 29 wt%, a maximum of about 28 wt%, a maximum of about 27 wt%, a maximum of about 26 wt%, a maximum of about 25 wt%, a maximum of about 23 wt%, a maximum of about 21 wt%, a maximum of about 20 wt%, a maximum of about 19 wt%, a maximum of about 17 wt%, a maximum of about 15 wt%, a maximum of about 13 wt%, or a maximum of about 11 wt%) of the etching composition of the present disclosure.

[0018] The etching composition of the present disclosure can optionally include one or more optional metal elements. The metal elements can be present in the etching composition in ionic form (e.g., metal ions) or non-ionic form (e.g., metals such as Sb). Examples of suitable metal elements include, but are not limited to, Sb, Cu, K, Ca, Na, Fe, Pb, Sr, As, Ni, Mn, Mg, and Li. In some embodiments, the amount of each metal element is at least about 0.1 ppb (e.g., at least about 0.5 ppb, at least about 1 ppb, at least about 2 ppb, at least about 4 ppb, at least about 5 ppb, at least about 6 ppb, at least about 8 ppb, at least about 10 ppb, at least about 15 ppb, at least about 20 ppb, at least about 25 ppb, or at least about 30 ppb) to a maximum of about 100 ppb (e.g., a maximum of about 95 ppb, a maximum of about 90 ppb, a maximum of about 80 ppb, a maximum of about 70 ppb, a maximum of about 60 ppb, a maximum of about 50 ppb, a maximum of about 40 ppb, or a maximum of about 30 ppb). In some embodiments, the amount of the Sb element is greater than the amount of each of the Cu, K, Ca, Na, Fe, Pb, Sr, As, Ni, Mn, Mg, and Li elements. The amount of the metal element in the etching composition can generally be measured by using inductively coupled plasma mass spectrometry. In some embodiments, the metal element is an impurity associated with the starting materials used to prepare the etching composition. Without wishing to be bound by theory, it is believed that the metal element can function as a metal etching inhibitor that can reduce the etching of certain metals exposed during an etching process that is not intended to be etched.

[0019] In some embodiments, the etching composition of the present disclosure can optionally include at least one (e.g., two, three, or four) metal corrosion inhibitor. Examples of suitable metal corrosion inhibitors include compounds of formula (A), compounds of formula (B), compounds of formula (C), or substituted tetrazole.

[0020] [Chemical formula]

[0021] In formula (A), R 1A ~R 5A are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group (e.g., a C1-C 10 alkyl group), a hydroxyl group, a thiol group, a carboxy group, or a substituted or unsubstituted amino group, provided that at least one group selected from a hydroxyl group, a carboxy group, and a substituted or unsubstituted amino group is included in formula (A). In formula (B), R 1B ~R 4B can each independently be a hydrogen atom, a hydroxyl group, or a substituted or unsubstituted hydrocarbon group (e.g., a C1-C 10 alkyl group). In general formula (C), R 1C , R 2C and R N can each independently be a hydrogen atom or a substituted or unsubstituted hydrocarbon group (e.g., a C1-C 10 alkyl group), or R 1C and R 2C together with the carbon atom to which they are attached form a ring (e.g., a 5-membered ring, 6-membered ring, or 7-membered ring). The ring can be aromatic or non-aromatic (e.g., containing 0 to 2 double bonds) and can contain 1 to 3 arbitrary heteroatoms such as O, N, or S. The ring can be substituted with at least one (e.g., 2, 3, or 4) substituents, such as a hydroxyl group, or a substituted or unsubstituted hydrocarbon group (e.g., a C1-C 10 alkyl group). Examples of suitable metal corrosion inhibitors include thioglycerol, catechol, pyrogallol, benzotriazole, and 5-methylbenzotriazole.

[0022] In some embodiments, the metal corrosion inhibitor is present in an amount ranging from at least about 0.0001% by weight (e.g., at least about 0.0002% by weight, at least about 0.0005% by weight, at least about 0.001% by weight, at least about 0.002% by weight, at least about 0.005% by weight, at least about 0.01% by weight, at least about 0.02% by weight, at least about 0.05% by weight, at least about 0.1% by weight, at least about 0.2% by weight, or at least about 0.5% by weight) to a maximum of about 1% by weight (e.g., up to about 0.9% by weight, up to about 0.8% by weight, up to about 0.7% by weight, up to about 0.6% by weight, up to about 0.5% by weight, up to about 0.4% by weight, up to about 0.3% by weight, up to about 0.2% by weight, up to about 0.1% by weight, up to about 0.05% by weight, or up to about 0.01% by weight) of the etching composition. While we do not wish to be bound by theory, it is thought that the aforementioned metal corrosion inhibitors can improve the selectivity of AlOx, W, and / or TiN removal from other metals (e.g., Cu) on the semiconductor substrate exposed during the etching process.

[0023] In some embodiments, the etching compositions of the present disclosure may optionally contain at least one (e.g., two, three, or four) aluminum etching surfactants. Examples of suitable aluminum etching surfactants include formula (D):RN(CH3)2-O(D)(R is C8-C 24 (For example, C 12 -C 18 This includes compounds that are alkyl. An example of a suitable aluminum etching surfactant is n-dodecyl-N,N-dimethylamine-N-oxide:

[0024] [ka]

[0025] In some embodiments, the aluminum etching surfactant is present in an amount ranging from at least about 0.0001% by weight (e.g., at least about 0.0002% by weight, at least about 0.0005% by weight, at least about 0.001% by weight, at least about 0.002% by weight, at least about 0.005% by weight, at least about 0.01% by weight, at least about 0.02% by weight, at least about 0.05% by weight, at least about 0.1% by weight, at least about 0.2% by weight, or at least about 0.5% by weight) to a maximum of about 1% by weight (e.g., up to about 0.9% by weight, up to about 0.8% by weight, up to about 0.7% by weight, up to about 0.6% by weight, up to about 0.5% by weight, up to about 0.4% by weight, up to about 0.3% by weight, up to about 0.2% by weight, up to about 0.1% by weight, up to about 0.05% by weight, or up to about 0.01% by weight) of the etching composition. While we do not wish to be bound by theory, it is thought that aluminum etching surfactants can improve the uniformity of semiconductor surfaces (for example, by improving the surface tension of the etching composition).

[0026] In some embodiments, the etching compositions of the present disclosure may optionally include a plurality of particles having an average size (e.g., average diameter) from at least about 0.1 μm (e.g., at least about 0.2 μm, at least about 0.3 μm, at least about 0.4 μm, at least about 0.5 μm, at least about 0.6 μm, or at least about 0.8 μm) to a maximum of about 1 μm (e.g., up to about 0.9 μm, up to about 0.8 μm, up to about 0.7 μm, up to about 0.6 μm, up to about 0.5 μm, up to about 0.4 μm, up to about 0.2 μm). In some embodiments, multiple particles are present in the etching composition in amounts of up to about 150 particles / ml (e.g., up to about 125 particles / ml, up to about 100 particles / ml, up to about 90 particles / ml, up to about 80 particles / ml, up to about 70 particles / ml, up to about 60 particles / ml, up to about 50 particles / ml, up to about 40 particles / ml, up to about 30 particles / ml, up to about 20 particles / ml, or up to about 10 particles / ml) and / or 0 particles / ml (e.g., at least about 5 particles / ml). Generally, particle size and particle count can be measured using a particle counter such as the Rion KS-42B. In some embodiments, the particles are impurities related to the starting material used to prepare the etching composition. While we do not wish to be bound by theory, it is thought that including an appropriate amount of particles (e.g., 10 to 100 particles / ml) in the etching compositions described herein can suppress abnormal etching such as pitting or spearhead etching. On the other hand, although we do not wish to be bound by theory, it is thought that if the etching composition contains more than 100 particles / ml, defects may occur on the surface of the semiconductor substrate.

[0027] In some embodiments, the etching compositions of the present disclosure may have a pH of up to about 1 (e.g., up to about 0.9, up to about 0.8, up to about 0.7, up to about 0.6, or up to about 0.5) and / or at least about 0 (e.g., at least about 0.1, at least about 0.2, at least about 0.3, at least about 0.4, or at least about 0.5). While we do not wish to be bound by theory, etching compositions with a pH higher than 1 are thought to lack sufficient AlOx, W, and / or TiN etching rates because sufficiently high acidity is required to remove these materials, and etching compositions with a pH lower than 0 are thought to decompose certain components in the composition due to their strong acidity.

[0028] Furthermore, in some embodiments, the etching compositions of this disclosure may optionally include additives such as pH adjusters, additional corrosion inhibitors, additional surfactants, organic solvents, biocides, and defoamers. Examples of suitable defoamers include polysiloxane defoamers (e.g., polydimethylsiloxane), polyethylene glycol methyl ether polymers, ethylene oxide / propylene oxide copolymers, and glycidyl ether-cap acetylenediol ethoxylates (e.g., those described in U.S. Patent No. 6,717,019, which is incorporated herein by reference). Examples of suitable surfactants may be cationic, anionic, nonionic, or amphoteric.

[0029] In general, the etching compositions of this disclosure can have relatively high W / dielectric material and / or TiN / dielectric material etching selectivity (i.e., a high ratio of W etching rate to dielectric material etching rate, and / or a high ratio of TiN etching rate to dielectric material etching rate). Examples of dielectric materials include SiO2, AlOx, high-k dielectric materials, and low-k dielectric materials. In some embodiments, the etching compositions can have W / dielectric material and / or TiN / dielectric material etching selectivity of at least about 2 (e.g., at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 30, at least about 40, or at least about 50) and / or up to about 500 (e.g., up to about 100).

[0030] In some embodiments, the etching compositions of the present disclosure may have relatively high AlOx / W and / or AlOx / TiN etching selectivity (i.e., a high ratio of AlOx etching rate to W etching rate and / or a high ratio of AlOx etching rate to TiN etching rate). In some embodiments, the etching compositions may have AlOx / W and / or AlOx / TiN etching selectivity of at least about 2 (e.g., at least about 3, at least about 4, at least about 5, at least about 6, at least about 7, at least about 8, at least about 9, at least about 10, at least about 15, at least about 20, at least about 30, at least about 40, or at least about 50) and / or up to about 500 (e.g., up to about 200 or up to about 100). Such etching compositions are suitable for use in relation to semiconductors comprising an AlOx layer having a relatively large thickness and a W or TiN layer having a relatively small thickness.

[0031] In some embodiments, the etching compositions of the present disclosure may specifically exclude (or substantially omit) one or more additive components, in the case of multiple components, in any combination. As used herein, the term “substantially omitted” means that the weight percent of the component is at most about 0.1% of the etching composition (e.g., at most about 0.05%, at most about 0.01%, at most about 0.005%, at most about 0.001%, or about 0%). Such excluded components include polymers, oxygen scavengers, quaternary ammonium salts (including quaternary ammonium hydroxide), amines, alkaline bases (such as NaOH, KOH, and LiOH), surfactants other than defoamers, defoamers, fluoride-containing compounds, oxidizing agents (e.g., peroxides, hydrogen peroxide, ferric nitrate, potassium iodate, potassium permanganate, nitric acid, ammonium chlorite, ammonium chlorate, ammonium iodate, ammonium perborate, ammonium perchlorate, ammonium periodate, ammonium persulfate, tetramethylammonium chlorite, tetramethylammonium chlorate, tetramethylammonium iodate, tetramethylammonium perborate, tetramethylammonium perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate) The following substances are selected from the group consisting of mononium, urea hydrogen peroxide, and peracetic acid; abrasives (e.g., silica or alumina abrasives); hydroxycarboxylic acids, carboxylic acids and polycarboxylic acids (e.g., those lacking an amino group) containing three or more hydroxyl groups; sulfonic acids; silanes (e.g., alkoxysilanes); cyclic compounds (e.g., cyclic compounds containing at least two rings, e.g., substituted or unsubstituted naphthalenes, or substituted or unsubstituted biphenyl ethers); chelating agents; buffering agents; non-azole corrosion inhibitors; azoles (e.g., diazoles, triazoles, or tetrazoles); and salts (e.g., sulfates, sulfonates, chlorides, nitrates, acetates, phosphates, and metal salts such as metal halides, potassium salts (e.g., potassium nitrate), sodium salts, and silver salts).

[0032] The etching compositions of this disclosure can be prepared by simply mixing the components together, or by blending two compositions in a kit. The first composition in the kit may be an aqueous solution of nitric acid. The second composition in the kit may contain the remaining components of the etching composition of this disclosure in a concentrated form in a predetermined ratio, such that the blend of the two compositions produces the desired etching composition of this disclosure.

[0033] In some embodiments, the Disclosure features a method for etching a semiconductor substrate containing AlOx, W, and / or TiN (for example, characterized by containing AlOx, W, and / or TiN). The method comprises contacting the semiconductor substrate containing AlOx, W, and / or TiN with an etching composition of the Disclosure to remove the AlOx, W, and / or TiN. The contact can be carried out at a temperature of at least about 20°C (e.g., at least about 25°C, at least about 30°C, at least about 40°C, at least about 50°C, or at least about 60°C) and / or up to about 95°C (e.g., up to about 90°C, up to about 80°C, or up to about 70°C). The method may further include rinsing the semiconductor substrate with a rinsing solvent after the contact step and / or drying the semiconductor substrate after the rinsing step. In some embodiments, the method does not substantially remove Cu or dielectric material (e.g., SiO2) from the semiconductor substrate. For example, the method does not remove more than approximately 5% by weight (e.g., more than approximately 3% by weight or more than approximately 1% by weight) of Cu or dielectric material from the semiconductor substrate.

[0034] In some embodiments, the etching method is (A) A step of providing a semiconductor substrate comprising AlOx, W and / or TiN, (B) A step of bringing a semiconductor substrate into contact with the etching composition described herein, (C) A step of rinsing the semiconductor substrate with one or more suitable rinsing solvents, (D) Optionally, a step of drying the semiconductor substrate (for example, by any suitable means that removes the rinse solvent and does not impair the integrity of the semiconductor substrate), Includes.

[0035] The semiconductor substrate containing AlOx, W, and / or TiN etched by this method may also contain organic and organometallic residues, as well as a range of metal oxides that may be removed during the etching process.

[0036] Semiconductor substrates are typically composed of group III-V compounds such as silicon, silicon germanium, and GaAs, or any combination thereof. Semiconductor substrates may further include exposed integrated circuit structures such as interconnection features (e.g., metal wires and dielectric materials). Metals and metal alloys used for interconnection features include, but are not limited to, aluminum, aluminum alloyed with copper, copper, titanium, tantalum, cobalt, silicon, titanium nitride, tantalum nitride, and tungsten. Semiconductor substrates may also include layers of interlayer dielectrics, silicon oxide, silicon nitride, silicon carbide, titanium oxide, and carbon-doped silicon oxide.

[0037] A semiconductor substrate can be brought into contact with the etching composition described herein by any suitable method, such as placing the etching composition in a tank and immersing and / or submerging the semiconductor substrate in the etching composition, spraying the etching composition onto the semiconductor substrate, streaming the etching composition onto the semiconductor substrate, or any combination thereof.

[0038] The etching compositions of this disclosure can be effectively used at temperatures ranging from room temperature (e.g., about 20-25°C) to about 95°C (e.g., about 55°C-95°C, about 60°C-90°C, about 60°C-80°C, or about 70°C). The etching rates of AlOx, W, and / or TiN generally increase with temperature in this range, and therefore processes at higher temperatures can be performed for shorter periods. Conversely, lower etching temperatures typically require longer etching times. In some embodiments, the inventors have found, surprisingly, that the etching compositions described herein can have a significantly higher increase in the AlOx etching rate at high temperatures (e.g., 70°C) compared to the increase in the W or TiN etching rate, thereby resulting in relatively high AlOx / W or AlOx / TiN etching selectivity at that temperature.

[0039] Etching times can vary over a wide range depending on the specific etching method, thickness, and temperature used. For immersion batch etching, a suitable time range is, for example, up to about 10 minutes (e.g., about 1 minute to 7 minutes, about 1 minute to 5 minutes, or about 2 minutes to 4 minutes). For single-wafer processes, the etching time may range from about 30 seconds to about 5 minutes (e.g., about 30 seconds to 4 minutes, about 1 minute to 3 minutes, or about 1 minute to 2 minutes).

[0040] Mechanical stirring means can be used to further enhance the etching ability of the etching composition of this disclosure. Examples of suitable stirring means include circulating the etching composition onto the substrate, streaming or spraying the etching composition onto the substrate, and ultrasonic or megasonic stirring during the etching process. The orientation of the semiconductor substrate relative to the ground can be at any angle. Horizontal or vertical orientation is preferred.

[0041] Following etching, the semiconductor substrate can be rinsed with a suitable rinsing solvent for about 5 seconds to about 5 minutes, with or without the use of stirring. Multiple rinsing steps using different rinsing solvents can be used. Examples of suitable rinsing solvents include, but are not limited to, deionized (DI) water, methanol, ethanol, isopropyl alcohol, N-methylpyrrolidinone, γ-butyrolactone, dimethyl sulfoxide, ethyl lactate, and propylene glycol monomethyl ether acetate. Alternatively, an aqueous rinse with pH > 8 (such as a diluted aqueous solution of ammonium hydroxide) can be used. Examples of rinsing solvents include, but are not limited to, diluted aqueous solution of ammonium hydroxide, DI water, methanol, ethanol, and isopropyl alcohol. The rinsing solvent can be applied using means similar to those used when applying the etching compositions described herein. The etching composition may be removed from the semiconductor substrate before the start of the rinsing step, or it may still be in contact with the semiconductor substrate at the start of the rinsing step. In some embodiments, the temperature used in the rinsing step is 16°C to 27°C.

[0042] Optionally, the semiconductor substrate is dried after the rinsing step. Any suitable drying method known in the art can be used. Examples of suitable drying methods include spin drying, flow of drying gas across the semiconductor substrate, or heating the semiconductor substrate with a heating means such as a hot plate or infrared lamp, Maragoni drying, Rotagoni drying, IPA drying, or any combination thereof. Drying time depends on the specific method used, but is typically on the order of 30 seconds to several minutes.

[0043] In some embodiments, the etching methods described herein further include forming a semiconductor device (e.g., an integrated circuit device such as a semiconductor chip) from a semiconductor substrate obtained by the above-described method.

[0044] The present disclosure is illustrated in more detail by reference to the following embodiments, which are for illustrative purposes only and should not be construed as limiting the scope of the present disclosure. [Examples]

[0045] The percentages listed are by weight (weight %) unless otherwise specified. Controlled stirring during the tests was performed at 300 rpm using a 1-inch stirring bar, unless otherwise noted.

[0046] General Procedure 1 Blended formula

[0047] Samples of the etching composition were prepared by adding the remaining components of the formulation to a calculated amount of water while stirring. After a homogeneous solution was obtained, optional additives (if used) were added.

[0048] General Procedure 2 Materials and methods

[0049] The etching rate of blanket films on films was measured using commercially available, unpatterned 300 mm diameter wafers diced into 0.5" × 0.5" evaluation test coupons. The main blanket film materials used in the test included: 1) W film with a thickness of approximately 1000 Å deposited on a silicon substrate, 2) TiN film with a thickness of approximately 1000 Å deposited on a silicon substrate, 3) HfOx film with a thickness of approximately 250 Å deposited on 1000 Å of SiO2 on a silicon substrate, and 4) AlOx film with a thickness of approximately 250 Å deposited on 1000 Å of SiO2 on a silicon substrate.

[0050] The thickness of blanket film test coupons was measured before and after treatment to determine the blanket film etching rate. For W and TiN metal blanket films, the film thickness was measured by sheet resistance using a CDE Resimap 273 with a 4-point probe. For HfOx and AlOx films, the film thickness was measured before and after treatment by ellipsometry using a Woollam M-2000X.

[0051] General Procedure 3 Etching evaluation by beaker test

[0052] All blanket film etching tests were performed at room temperature (21-23°C; unless otherwise specified) in a 600 ml glass beaker containing 200 g of sample solution, with the Parafilm® cover always in place to minimize evaporation loss, and with continuous stirring at 250 rpm. All blanket test coupons with blanket metal or dielectric film exposed on one side to the sample solution were die-cut to a 0.5” × 0.5” square test coupon size for beaker-scale testing using a diamond scribe, and each test coupon was held in place using a single 4” long fixed plastic tweezers clip. The test coupons, held at one edge by the fixed tweezers clip, were suspended in a 600 ml glass beaker and immersed in 200 g of test solution, while the solution was continuously stirred at 250 rpm at room temperature. Each sample coupon was stirred and dissolved. Immediately after immersion in the solution, the top of the 600 mL glass beaker was covered with Parafilm® and resealed. The test coupons were kept stationary in the stirred solution until the processing time (as described in general procedure 3A) had elapsed. After the processing time in the test solution had elapsed, the sample coupons were immediately removed from the 600 mL glass beaker and rinsed according to general procedure 3A. After the final DI rinsing step, all test coupons were subjected to a filtered nitrogen gas blowing step using a handheld nitrogen gas blower, thereby forcibly removing all trace amounts of DI water to prepare final dry samples for test measurement.

[0053] General Procedure 3A (Blanket Test Coupon)

[0054] Immediately after the 10-minute processing time according to General Procedure 3, the test coupon was immersed in 1000 ml of ultra-high purity deionized (DI) water at 20°C at an overflow rate of approximately 1 liter / minute for 30 seconds, and then immersed for another 30 seconds with gentle stirring. The process was completed according to General Procedure 3.

[0055] Example 1

[0056] Formulations 1-4 (FE-1-FE-4) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and test results are summarized in Table 1.

[0057] [Table 1]

[0058] As shown in Table 1, FE-2 showed improved TiN and W etching rates compared to FE-1 as the amount of water increased from FE-1 to FE-2. Furthermore, the etching rates of TiN and W also increased as the amount of nitric acid increased from FE-2 to FE-4.

[0059] Example 2

[0060] Formulations 5-8 (FE-5-FE-8) were prepared according to general procedure 1 and evaluated according to general procedures 2 and 3. The formulations and test results are summarized in Table 2.

[0061] [Table 2]

[0062] As shown in Table 2, the etching rates of TiN and W also increased as the amount of water increased from FE-5 to FE-8.

[0063] Example 3

[0064] Formulations 9-12 (FE-9-FE-12) were prepared according to general procedure 1 and evaluated according to general procedures 2 and 3. The formulations and test results are summarized in Table 3.

[0065] [Table 3]

[0066] As shown in Table 3, in the absence of nitric acid, FE-9 exhibited very low etching rates for TiN and W. Furthermore, as the amount of nitric acid increased from FE-10 to FE-11, the etching rates for TiN and W also increased. Subsequently, as the amount of water decreased from FE-11 to FE-12, the etching rates for TiN and W decreased.

[0067] While the present invention has been described in detail with reference to its specific embodiments, modifications and variations will be understood to be within the spirit and scope of what has been described and claimed.

[0068] Example 4

[0069] Formulations 13-19 (FE-13-FE-19) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and test results are summarized in Table 4.

[0070] [Table 4]

[0071] As shown in Table 4, the HfOx etching rate decreased as the Sb content increased from FE-13 to FE-16. Furthermore, when the Sb content was greater than 100 ppb (FE-17) or less than 1 ppb (in FE-18), the formulations exhibited relatively high HfOx etching rates. While we do not wish to be bound by theory, it is thought that Sb can form an insoluble passivation layer on the HfOx surface, thereby reducing its etching rate during the etching process.

[0072] Example 5

[0073] Formulations 20-27 (FE-20-FE-27) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and test results are summarized in Table 5. The formulation and test results for FE-2 are also included in Table 5 for comparison.

[0074] [Table 5]

[0075] As shown in Table 5, when certain additives (e.g., metal corrosion inhibitors and aluminum etching surfactants) were added, the TiN / W etching rate ratio improved and approached 1.

[0076] Example 6

[0077] Formulations 28-32 (FE-28-FE-32) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and test results are summarized in Table 6.

[0078] [Table 6]

[0079] Evaluation of abnormal etching (Spearhead): 1. No spearhead (less than 1%) 2. Small spearhead (less than 3%) 3. A certain degree of spearhead (less than 5%) 4. Severe spearhead (over 10%)

[0080] As shown in Table 6, when 0.5 micron-sized particles were present and their quantity increased, the formulation showed a decrease in abnormal etching, such as spearhead etching.

[0081] Example 7

[0082] Formulations 33-39 (FE-33-FE-39) were prepared according to General Procedure 1 and evaluated according to General Procedures 2 and 3. The formulations and test results are summarized in Table 7. The formulation and test results for FE-2 are also included in Table 7 for comparison.

[0083] [Table 7]

[0084] As shown in Table 7, the weight percentages of H3PO4, HNO3, and HAc are important for controlling the spearhead.

[0085] Comparative Example

[0086] Comparative formulations CFE-1 to CFE-6 were prepared according to general procedure 1 and evaluated according to general procedures 2 and 3. The formulations and test results are summarized in Table 8. The formulation and test results for FE-2 are also included in Table 8 for comparison.

[0087] [Table 8]

[0088] As shown in Table 8, abnormally poor etching rates were observed when (1) the weight percentage of H3PO4 was greater than 90% or less than 65% (see CFE-1 and CFE-2), (2) the weight percentage of HNO3 was less than 0.01% or greater than 5% (see CFE-3 and CFE-4), and (3) the weight percentage of HAc was less than 0.01% or greater than 4% (see CFE-5 and CFE-6).

[0089] Example 8

[0090] Formulations 40-57 (FE-40-FE-57) were prepared according to general procedure 1 and evaluated according to general procedures 2 and 3. Etching tests were performed at 70°C. The formulations and test results are summarized in Table 9.

[0091] [Table 9]

[0092] As shown in Table 9, FE-40 to FE-57 exhibited high etching selectivity for Al2O3 / W and Al2O3 / TiN, along with a high Al2O3 etching rate, at an etching temperature of 70°C.

[0093] Example 9

[0094] Formulation Example 58 (FE-58) was prepared according to General Procedure 1 and aged for a set period (i.e., 1 hour, 4 hours, 8 hours, or 24 hours), and then evaluated according to General Procedures 2 and 3 at different etching temperatures (i.e., 25°C, 50°C, and 70°C). FE-58 contained 74 wt% phosphoric acid, 0.5 wt% acetic acid, 0.5 wt% nitric acid, and 25 wt% water. The test results are summarized in Table 10.

[0095] [Table 10]

[0096] As shown in Table 10, increasing the etching temperature from 25°C to 70°C increased the etching rate of all three materials tested (i.e., W, Al2O3, and TiN). Furthermore, the increase in etching temperature from 25°C to 70°C resulted in a greater increase in the etching rate of Al2O3 than that of W and TiN, resulting in higher etching selectivity for Al2O3 / W and Al2O3 / TiN. Exemplary embodiments of the present invention are described below. <1> Etching composition, The composition contains phosphoric acid in an amount of about 65% to about 90% by weight, The composition contains acetic acid in an amount of about 0.01% to about 4% by weight, Nitric acid in an amount of about 0.01% to about 5% by weight of the above composition, Water and, An etching composition containing the following: <2> The phosphoric acid is present in an amount of about 70% to about 85% by weight of the composition. <1> The composition described above. <3> The phosphoric acid is present in an amount of about 72% to about 76% by weight of the composition. <1> The composition described above. <4> The acetic acid is present in an amount of about 0.1% to about 3.5% by weight of the composition. <1> The composition described above. <5> The acetic acid is present in an amount of about 0.3% to about 0.7% by weight of the composition. <1> The composition described above. <6> The nitric acid is present in an amount of about 0.05% to about 4% by weight of the composition. <1> The composition described above. <7> The nitric acid is present in an amount of about 0.3% to about 0.7% by weight of the composition. <1> The composition described above. <8> The water is present in an amount of about 10% to about 30% by weight of the composition. <1> The composition described above. <9> Sb further includes <1> The composition described above. <10> The aforementioned Sb is present in the composition in an amount of about 1 ppb to about 100 ppb. <9> The composition described above. <11> It further comprises one or more metallic elements selected from the group consisting of Cu, K, Ca, Na, Fe, Pb, Sr, As, Ni, Mn, Mg, and Li. <9> The composition described above. <12> The amount of Sb is greater than the amounts of each of Cu, K, Ca, Pb, Sr, As, Ni, Mn, Mg, and Li. <9> The composition described above. <13> The amount of Sb is greater than the respective amounts of Na and Fe. <9> The composition described above. <14> Further comprising at least one metal corrosion inhibitor, <1> The composition described above. <15> The at least one metal corrosion inhibitor comprises a compound of formula (A), a compound of formula (B), a compound of formula (C), or a substituted tetrazole. <14> The composition described:

change

Claims

[Claim 1] An etching composition for selectively etching AlOx, W, and / or TiN, The composition contains phosphoric acid in an amount of 65% to 89% by weight, The composition contains 0.01% to 4% by weight of acetic acid, Nitric acid in an amount of 0.01% to 5% by weight of the above composition, Water and, An etching composition containing the following:

Images