KR20130007419A - Method of forming capacitor structure and silicon etching liquid used in the same - Google Patents

Abstract

PURPOSE: A method for forming a capacitor structure and a silicon etching solution used in the same are provided to efficiently and accurately remove amorphous silicon or polycrystal silicon. CONSTITUTION: A method for forming a capacitor structure is as follows. A first coat film(1) and a second coat film(2) are formed on a silicon wafer(3). A photoresist(4) is patterned and opened using anisotropic dry etching technique to form concave portions(Ka). A conductive film is formed along the wall surfaces of the concave portions and the top surface of the second coat film. A laying film for protecting the conductive film is formed on the conductive film. The second coat film and the laying film are removed using wet etching technique. A capacitor structure is formed by successively forming a lower electrode, a capacity insulation layer, and an upper electrode.

Description

METHOD OF FORMING CAPACITOR STRUCTURE AND SILICON ETCHING LIQUID USED IN THE SAME

The present invention relates to a method of forming a capacitor structure and a silicon etchant used therein.

Conventionally, a concave type has been adopted as a capacitor structure of DRAM. In this structure, a lower electrode film is formed in the cylinder hole, and only its inner surface functions as an electrode. According to this, although the area which a capacitor occupies can be made small certainly, the diameter of a cylinder hole also inevitably reduces. On the other hand, the capacity required for DRAM device operation must be secured. In order to satisfy both, the depth of the cylinder hole becomes deeper, and the correspondence in the microfabrication technique becomes difficult. In response to such a situation, there is also proposed a crown capacitor capable of reducing the aspect ratio of the capacitor by using not only the inside but also the outside of the lower electrode of the cylinder structure (see Patent Document 1, for example).

Efforts have been made to suppress the aspect ratio of the capacitor structure as described above. However, it is not easy to process the microcylindrical structure and the hole by precisely forming them. Usually this process is performed by wet etching. That is, the inside and outside members must be removed by the etching solution so as to leave the cylindrical structure having a cylinder wall with a depth of nanometer to submicrometer size on the semiconductor substrate. In particular, removal in the cylinder hole involves difficulty as processing performed by wet etching as the material must be removed from the enclosed space. Moreover, in the part where the cylinder structure is dense, etching becomes difficult also in the same situation outside the hole. It is also considered to apply a solvent having a high etching power while focusing on the workability, but there is a concern that the electrode and other parts may be corroded by the action. In addition, the tendency than that of the filler material in order to increase the aspect ratio changed to a polysilicon or amorphous silicon from the SiO _2, should do not enable a good response to this etching.

Japanese Patent Publication No. 2010-199136

By the way, formation of a capacitor structure may be carried out by the batch type | mold washing | cleaning apparatus and the case of a single | leaf type washing | cleaning processing apparatus. In either system, since the etching process is performed for a predetermined time under a predetermined temperature condition, the activity of the etching solution is preferably maintained during that time. In particular, since the etching liquid is used for washing in a circulated state when the sheet is single-leaf type, it is required that the processing capacity does not decrease even when the circulation is maintained at this predetermined temperature, that is, it has a long life.

Therefore, the present invention can accurately and efficiently remove amorphous silicon or polycrystalline silicon so as to form an uneven shape on a semiconductor substrate, and furthermore, to form a silicon etching solution and a capacitor structure using the same, in which the activity is maintained for a long time under the conditions in which the etching is performed. To provide a method.

The above problem has been solved by the following means.

(1) A silicon etching solution containing a combination of ammonia, at least one specific basic compound selected from the group consisting of a hydroxylamine compound, a basic organic compound, and a metal-containing basic compound is applied to a polycrystalline silicon film or an amorphous silicon film. And forming at least one portion of the polycrystalline silicon film or the amorphous silicon film to form a concave-convex shape serving as a capacitor.

(2) The method according to (1), wherein the specific basic compound is at least one selected from the group consisting of tetramethylammonium hydroxide, potassium hydroxide, a hydroxylamine compound, and an alkanolamine.

(3) The formation method as described in (1) or (2) whose content ratio (M _A / M _SB ) of the mass (M _A ) of the said ammonia and the mass (M _SB ) of the said specific basic compound is 0.1-10.

(4) The formation method in any one of (1)-(3) whose density | concentration of the said ammonia is 5-25 mass%.

(5) The formation method in any one of (1)-(4) whose density | concentration of the said specific basic compound is 1-25 mass%.

(6) The formation method according to any one of (1) to (5), wherein at least a part of the polycrystalline silicon film or the amorphous silicon film is removed by the sheet processing apparatus.

(7) The formation according to any one of (1) to (6), wherein the etching solution is composed of an A agent containing the ammonia and a B agent containing the specific basic compound, and the A agent and the B agent are mixed at the time of use. Way.

(8) The formation method in any one of (1)-(7) in which the uneven | corrugated shape part which comprises the said capacitor structure contains TiN.

(9) The formation according to any one of (1) to (8), wherein the silicon etching solution removes at least a portion of the polycrystalline silicon film or the amorphous silicon film to form a trench structure having an aspect ratio (depth / opening width) of 10 or more. Way.

(10) The etching according to any one of (1) to (9), wherein the polycrystalline silicon film or the amorphous silicon film is etched while leaving an electrode film made of TiN, Ti, or W at least on the wall surface of the uneven structure. Forming method characterized by.

(11) The semiconductor substrate according to any one of (1) to (10), wherein the semiconductor substrate having a substantially flat surface having the polycrystalline silicon film or the amorphous silicon film is prepared, and the etching solution is applied to the surface of the semiconductor substrate. And removing the polycrystalline silicon film or the amorphous silicon film to form the recessed portion, and the convex portion left in the substrate as the lower electrode of the capacitor.

(12) The formation method according to (11), wherein the convex portion is made of TiN.

(13) An etchant for forming a capacitor structure by removing at least a part of a polycrystalline silicon film or an amorphous silicon film to form a concave-convex shape serving as a capacitor, comprising an ammonia, a hydroxylamine compound, a basic organic compound, and a metal-containing basic compound. A silicon etching solution comprising at least one specific basic compound selected from the group in combination.

(14) The etching liquid according to (13), wherein the specific basic compound is at least one selected from the group consisting of tetramethylammonium hydroxide, potassium hydroxide, hydroxylamine compound, and alkanolamine.

(15) The etching liquid according to (13) or (14), wherein a content mass ratio of the ammonia and the specific basic compound is 0.1 to 10.

(16) The etching liquid in any one of (13)-(15) whose density | concentration of the said ammonia is 5-25 mass%.

The etching liquid in any one of (17) (13)-(16) whose density | concentration of the said specific basic compound is 1-25 mass%.

(18) The etching liquid according to any one of (13) to (17), which is used in a sheet processing apparatus.

(19) The kit according to any one of (13) to (18), comprising a agent A containing the ammonia and a agent B containing the specific basic compound, wherein both kits are mixed and used at the time of use. Etching liquid.

(20) The etching liquid in any one of (13)-(18) in which the uneven | corrugated shape part which comprises the said capacitor structure contains TiN.

(Effects of the Invention)

According to the silicon etching solution of the present invention and a method of forming a capacitor structure using the same, amorphous silicon or polycrystalline silicon can be removed accurately and efficiently so as to form an uneven shape on a semiconductor substrate, and furthermore, long-term activity is performed under the conditions under which the etching is performed. It is excellent to maintain. In addition, according to the present invention, the removal of the etching residue is also simultaneously achieved as necessary, thereby making the process more efficient.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically the manufacturing process example of the capacitor structure applied to this invention.
It is sectional drawing which shows typically the example of the manufacturing process of the capacitor structure applied to this invention (continuation of FIG. 1).
3 is a cross-sectional view schematically showing an example of the manufacturing process of the capacitor structure applied to the present invention (continued in FIG. 2).
It is sectional drawing which shows typically the example of the manufacturing process of the capacitor structure applied to this invention (continuation of FIG. 3).
5 is a cross-sectional view schematically showing another example of a capacitor structure applied to the present invention.
6 is a cross-sectional view schematically showing another example of the manufacturing process of the capacitor structure applied to the present invention.
FIG. 7 is a cross-sectional view taken along the line VII-VII shown in FIG. 6. FIG.

[Formation of Capacitor Structure]

First, before demonstrating the etching liquid by this invention, the manufacture example of the capacitor structure which can be preferably employ | adopted in this invention is demonstrated based on FIGS. In addition, although the formation of a capacitor structure is mainly demonstrated in the following detailed description, this invention is limited to this and is not interpreted.

(Step a)

In the manufacturing example of the present embodiment, the first molded film 1 and the second molded film 2 are formed on the silicon wafer 3. The 1st shaping | molding film 1 is an etching stopper film | membrane at the time of opening of a cylinder hole, and is a film which has an etching rate ratio by the 2nd shaping | molding film 2 and an anisotropic dry etching process. As the 1st molded film 1, the nitride film formed by the LP-CVD process, etc. are mentioned, for example. On the other hand, the film of polycrystalline silicon or amorphous silicon can be mentioned for the 2nd shaping | molding film 2, for example. Although not shown, a protective film may be formed.

In addition, although the silicon wafer 3 is greatly simplified and shown as a single | mono layer, normally, the predetermined circuit structure is formed here. For example, those using a separation insulating film, a gate oxide film, a gate electrode, a diffusion layer region, a polysilicon plug, a silicon oxide film, a silicon nitride film, a bit line, a metal plug, a nitride film, a plasma oxide film, a BPSG film, and the like can be mentioned. For example, refer to the said patent document 1). In addition, although hatching is given in particular in FIGS. 1-5, the cross section of each member is shown (the lower figure of FIG. 3 (f) is a top view).

(Step b)

Subsequently, the photoresist 4 is patterned using a photolithography step, and then opened by anisotropic dry etching (concave portion Ka). As for the photoresist 4 and the method of dry etching at this time, any ordinary water or method applied to this kind of product may be applied.

(Step c), (Step d)

Further, after the opening, a conductive film 5 made of TiN is formed along the wall surface Wa of the recess Ka and the upper surface Wb of the molded film (silicon film) 2. Further, further, a buried film 6 (for example, a film of polycrystalline silicon or amorphous silicon) for protecting the conductive film 5 is sequentially formed so as to fill the recess. At this time, the recessed part formed intermediately (after formation of the conductive film 5) is shown as Kb.

(Step e)

After the deposition film 6 is formed, a part of the buried film 6 and the conductive film 5 (FIGS. 2 and 3) on the wafer surface is removed by chemical mechanical polishing (CMP) to remove the etch back line ( E). Here, the second insulating film 2 and the buried film 6 are removed by wet etching. In this invention, this process is important and the etching liquid by this invention mentioned later exhibits a high effect. Through this process, the lower electrode (cylinder wall) 50 (FIG. 3) of the capacitor having the cylinder hole Kc is formed. Although the depth h ₂ of the cylinder hole wall is not particularly limited, considering the normal structure of this kind of device, it is practical that it is 500 to 2000 nm. Moreover, it is preferable to apply the etching liquid of this invention to the surface smoothed by etch back etc. as mentioned above, and to remove a buried film from it, and to form a trench structure.

(Process f)

After forming the lower electrode 50 of the capacitor formed as described above, the capacitor insulating film 9 is formed, and then the capacitor structure 10 is formed by sequentially forming plate electrodes (upper electrodes) (not shown). Can be. In the present specification, the capacitor structure may be either the capacitor itself or a structural portion constituting a part of the capacitor. In the example shown in FIG. 4, the capacitor structure 10 is formed by the lower electrode 50 and the capacitor insulating film 9. It is shown. In addition, although shown in the figure as the structure which isolate | separated the lower electrode 50 and the wafer 3 by the shaping | molding film 1, it understands that it is a structure in which both were electrically connected at the same drawing or another position as needed. Also good. For example, a plug structure or a damascene structure may be formed in a portion of the molded film 1 to secure conduction, or the lower electrode 50 may be formed to pass through the molded film 1. . The capacitor insulating film may be formed not only on the lower electrode 50 but also on the other substrate surface.

5 shows a modification of the capacitor structure of the above embodiment. In this example, the bottom portion 81 and the main portion 82 of the lower electrode (cylinder structure) are made of different materials. For example, there may be mentioned an example of constituting the bottom (81) with Si ₃ N _4, and constituting the main part 82 as TiN. In addition, the structure is shown as sectional drawing in FIG.

Next, based on FIG. 6, FIG. 7, the modification (the form with the protection part 7) of the said embodiment is demonstrated. In this embodiment, the electrode protective film 7 is formed. It is preferable that an electrode protective film is an insulating film which has sufficient tolerance with respect to the wet etching liquid used for the removal of the silicon material at the time of capacitor structure formation. Moreover, it is preferable that it can form into a film all over the cylinder hole Ka uniformly. For example, a nitride film, a tantalum pentoxide (Ta ₂ O ₅ ) film, etc. using ALD (Atomic Layer Deposition) method are mentioned. The order of forming this is not particularly limited, but after the growth of the electrode protective film, the electrode protective film is removed by isotropic etching. Specifically, first, the molded film 2 is composed of three layers including the molded layer 21 (Fig. 6 (a)). Although this is etched, what is easy to be etched in the isotropic etching of the molded film 21 is employ | adopted. Therefore, the recessed part Va is formed in this part by isotropic etching (FIG. 6 (b)). Then, when a protective film (not shown) is formed, the surface is covered with a protective film including this depression formed on the wall surface of the recess Ka. That is, an electrode protective film is filled in this recessed part. After that, when isotropic etching is performed, only the protection part 7 is left. Thereafter, the lower electrode 50 can be formed by applying the conductive film 5 as in the above embodiment. Subsequently, when the silicon film and the buried film are removed with the etching solution of the present embodiment, an electrode protective portion (not shown) protruding therefrom when the lower lower electrode 50 is formed can be formed (Fig. 6 (c)). The structure and advantage of this electrode protection protrusion are disclosed in detail in Japanese Patent Laid-Open No. 2010-199136.

In the present modification, it is difficult to remove the buried film from the cylinder hole Kc, since the protective part 7 is present from the beginning, so that the molded film 2 from the gap (concave-shaped part) Kd between the electrodes 50 can be obtained. It is also difficult to remove. Rather, the protective portion 7 protruding outward may function like a weir, making it difficult to remove and release the molded film underneath. Since the etching liquid of this invention exhibits especially high effect in the form which such removal is difficult, the application is preferable.

[Silicon etching solution]

Next, preferable embodiment of the silicon etching liquid of this invention which can be used very effectively for the wet etching demonstrated in the said process e is described. In the etching solution of the present embodiment, a combination of ammonia and a specific basic compound is used to accurately remove a polycrystalline silicon film or an amorphous silicon film by forming a capacitor structure having an uneven shape as described above without damaging a member such as an electrode. Made it possible to do. The detailed reason includes the point of unexplained, but is estimated as follows. That is, since ammonia is low molecular weight and low pKb, many hydroxyl groups can be contained in a system. Therefore, a high silicon etching rate can be realized. However, ammonia tends to volatilize and the expression period of the effect tends to be very short. Although it is not clear in detail, it is thought that by combining a specific basic compound, it becomes possible to hold a hydroxyl group in a long term system, and to maintain a high etching rate for a long time.

In addition, in this specification, the liquid which combined the specific agent means not only the liquid composition containing the said agent, but also includes the meaning as a kit which mixes each agent or the liquid containing it before use, and uses it.

(ammonia)

The etching liquid of this embodiment contains ammonia as an essential component. It is preferable that the density | concentration of ammonia is 5-25 mass%, and it is more preferable that it is 10-20 mass%. By carrying out more than the said lower limit, high etching rate can be implement | achieved. Moreover, the time-dependent decline of an etching rate can be made gentle by using below the said upper limit.

(Specific basic compounds)

The etching liquid of this embodiment contains specific basic compounds other than ammonia with ammonia. The specific basic compound is selected from the group consisting of a hydroxylamine compound, a basic organic compound, and a metal-containing basic compound.

Basic organic compound

It is preferable to have carbon and nitrogen as a structural element of a basic organic compound, and it is more preferable to have an amino group. Specifically, the basic organic compound is preferably at least one compound selected from the group consisting of organic amines and quaternary ammonium hydroxides. In addition, an organic amine means the amine containing carbon as a structural element.

Examples of the organic amine used as the organic alkali compound of the etching solution of the present embodiment include alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, diethylene glycol amine, N-hydroxyethyl piperazine, and / or ethylamine, Benzylamine, diethylamine, n-butylamine, 3-methoxypropylamine, tert-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, o-xylenediamine, m Hydroxyl groups such as xylylenediamine, 1-methylbutylamine, ethylenediamine (EDA), 1,3-propanediamine, 2-aminobenzylamine, N-benzylethylenediamine, diethylenetriamine, triethylenetetramine Organic amines that do not have. Alkanolamines are preferable from the viewpoint of effectively exerting the above-mentioned action, and among them, monoethanolamine, diethanolamine, triethanolamine, diethylene glycol amine, ethylenediamine (EDA), 1,3-propanediamine and diethylenetriamine And triethylenetetramine are preferred. In addition, in description of a compound and group (atom group) in this specification, the description which is not describing substitution and unsubstitution includes what has a substituent with the thing which does not have a substituent. For example, an "alkyl group" includes not only the alkyl group (unsubstituted alkyl group) which does not have a substituent but the alkyl group (substituted alkyl group) which has a substituent.

As quaternary ammonium hydroxide used as an alkali compound, tetraalkylammonium hydroxide is preferable, tetraalkylammonium hydroxide substituted by a lower (C1-C4) alkyl group is more preferable, Specifically, tetramethylammonium hydroxide (TMAH) ), Tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH) and the like. Further, as the quaternary ammonium hydroxide, trimethylhydroxyethylammonium hydroxide (choline), methyltri (hydroxyethyl) ammonium hydroxide, tetra (hydroxyethyl) ammonium hydroxide, benzyltrimethylammonium hydroxide (BTMAH ) And the like. In addition, a combination of ammonium hydroxide and one or more quaternary ammonium hydroxides may be used. Among these, TMAH, TEAH, TPAH, TBAH and choline are more preferable, and TMAH and TBAH are particularly preferable.

These organic amines and quaternary ammonium hydroxides can be used individually by 1 type or in mixture of 2 or more types.

In addition, in this specification, when the term "compound" is called at the end, or when represented by a specific name or chemical formula, it is used in the meaning including the salt, a complex, and the ion in addition to the said compound itself. In addition, it is the meaning containing the derivative modified by the predetermined form in the range which shows the desired effect. In addition, it is a meaning which may have arbitrary substituents in the group about the substituent which does not specify substitution and unsubstitution in this specification. This is also true for compounds that do not specify substitution or non-substitution. As the preferable substituent, the following substituent T can be mentioned.

(T exchanger T)

Alkyl groups (preferably alkyl groups having 1 to 20 carbon atoms, for example methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.) , Alkenyl groups (preferably alkenyl groups having 2 to 20 carbon atoms, for example, vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups having 2 to 20 carbon atoms, for example, ethynyl , Butadiinyl, phenylethynyl, etc.), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), aryl group ( Preferably an aryl group having 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl and the like, a heterocyclic group (preferably 2 to carbon atoms) 20 heterocyclic groups such as 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzoimidazolyl, 2-thiazolyl, 2-oxazole Etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably having 6 to 26 carbon atoms) Aryloxy groups such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy and the like, alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, for example) , Ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc.), amino group (preferably amino group having 0 to 20 carbon atoms, for example, amino, N, N-dimethylamino, N, N-diethylamino , N-ethylamino, anilino, etc.), sulfonamide groups (preferably sulfonamide groups having 0 to 20 carbon atoms, for example, N, N-dimethylsulfonamide, N-phenylsulfonamide, etc.), acyl ox Period (preferably acyloxy group of 1-20 carbon atoms, for example, acetyloxy, benzoyloxy, etc.), carbamoyl group (bar Preferred are carbamoyl groups having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl and N-phenylcarbamoyl, acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms, For example, acetylamino, benzoylamino, etc.), cyano group, or halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), and more preferably an alkyl group, an alkenyl group, an aryl group, hetero Ventilation, alkoxy group, aryloxy group, alkoxycarbonyl group, amino group, acylamino group, cyano group or halogen atom, particularly preferably alkyl group, alkenyl group, heterocyclic group, alkoxy group, alkoxycarbonyl group, amino group, acylamino group or cyano group Can be mentioned.

Hydroxylamine compounds

In this invention, a hydroxylamine compound can be used as a specific basic compound. As a hydroxylamine compound, the salt of hydroxylamine is mentioned besides hydroxylamine. Examples of the salt of the hydroxylamine include hydroxylamine nitrate (also called HAN), hydroxylamine sulfate (also called HAS), hydroxylamine phosphate, hydroxylamine hydrochloride and the like. The organic acid salt of hydroxylamine can also be used for etching liquid, and hydroxylamine citrate, hydroxylamine oxalate, etc. can be illustrated. Inorganic acid salts, such as hydroxylamine nitrate, hydroxylamine sulfate, hydroxylamine phosphate, and hydroxylamine hydrochloride, are inert with respect to metals, such as aluminum, copper, and titanium, among these salts of hydroxylamine. In particular, hydroxylamine nitrate and hydroxylamine sulfate are preferable. These hydroxylamine compounds can be used individually by 1 type or in mixture of 2 or more types.

Metal-containing basic compound

Examples of the metal-containing basic compound include potassium hydroxide, sodium hydroxide, lithium hydroxide, cesium hydroxide and calcium hydroxide. Among them, potassium hydroxide and sodium hydroxide are preferable, and potassium hydroxide is more preferable.

In this invention, it is preferable to make an etching liquid contain ammonia and 2 or more types of specific basic compounds. It is preferable that it is a combination of a hydroxylamine compound, a basic organic compound, and / or a basic inorganic compound as a combination of 2 or more types of specific basic compounds, Especially, the combination of a hydroxylamine compound and a quaternary ammonium hydroxide is more preferable, Particular preference is given to combinations of at least a hydroxylamine compound with TMAH and / or MEA.

It is preferable to contain content of a specific basic compound within the range of 1-25 mass% with respect to the total mass of the etching liquid of this embodiment, and it is more preferable to contain 1-15 mass%. Since a high etching rate can be maintained by using below the said upper limit and above the lower limit, it is preferable. Moreover, since performance is saturated, it is good to respond below the said upper limit also from the viewpoint.

Moreover, it is preferable that the content ratio (M _A / M _SB ) of the mass (M _A ) of ammonia and the mass (M _SB ) of a specific basic compound is 0.1-10, and it is more preferable that it is 0.3-5. Since the etching rate can be maintained by using below the said upper limit, it is preferable. Since a high etching rate can be obtained by using more than the said lower limit, it is preferable. In addition, 1 type may be used for a specific basic compound, or may be used for it in combination of 2 or more type.

As mentioned above, although specific basic compounds, such as a hydroxylamine salt, may use the salt which consists of an anion, in this invention, when using the salt of an anion derived from a strong acid, pH in an system etc. is kept alkaline by addition of a basic compound, etc. It is preferable.

(pH)

It is preferable that the silicon etching liquid of this invention is alkaline, and is adjusted to pH8 or more. This adjustment can be performed by adjusting the addition amount of the said alkali compound and the hydroxylamine compound. However, as long as the effect of this invention is not impaired, you may make it the pH of the said range using another pH adjuster. It is preferable that it is 9 or more, and, as for pH of a silicon etching liquid, it is more preferable that it is 11 or more. Sufficient etching rate can be obtained when this pH is more than the said lower limit. Although there is no upper limit in particular in the said pH, it is practical that it is 14 or less.

(Other ingredients)

Addition of organic solvent

In the silicon etching liquid of this invention, you may add the water-soluble organic solvent further. This is effective in that the uniform etching property in the surface of the wafer can be further improved. Water-soluble organic solvents are alcohols (for example, ethylene glycol, glycerin, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, propylene glycol, furfuryl alcohol, 2-methyl-2,4-pentane Diol), glycols (for example, diethylene glycol, dipropylene glycol, dipropylene glycol methyl ether, propylene glycol monopropylene glycol), dimethyl sulfoxide, ethers (for example, ethylene glycol dimethyl ether, diethylene glycol Dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and propylene glycol dimethyl ether) are preferable. It is preferable that it is 0.1-20 mass% with respect to etching liquid whole quantity, and, as for an addition amount, it is more preferable that it is 1-15 mass%. When this quantity is more than the said lower limit, the improvement of the uniformity of the said etching can be implement | achieved effectively. On the other hand, when it is below the said upper limit, it can be said that wetting property with respect to a polycrystalline silicon film, an amorphous silicon film, and other metal films is ensured.

· Addition of surfactants

The silicon etching solution of the present invention may further contain a surfactant. As the surfactant, nonionic, anionic, cationic surfactants, and amphoteric surfactants can be used. Content of surfactant in antioxidant liquid becomes like this. Preferably it is 0.0001-5 mass% with respect to the total mass of antioxidant liquid, More preferably, it is 0.0001-1 mass%. It is preferable because the viscosity can be adjusted by adding the surfactant to the antioxidant solution to further improve the in-plane uniformity of etching. Such surfactants are generally commercially available. You may use these surfactant individually or in combination of 2 or more.

As a nonionic surfactant, For example, polyalkylene oxide alkyl phenyl ether type surfactant, polyalkylene oxide alkyl ether type surfactant, the block polymer type surfactant which consists of polyethylene oxide and a polypropylene oxide, polyoxyalkylene disstyreneization Phenyl ether type surfactant, a polyalkylene tribenzyl phenyl ether type surfactant, and an acetylene polyalkylene oxide type surfactant are mentioned.

As anionic surfactant, Alkyl sulfate ester, alkyl sulfonic acid, alkylbenzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether sulfonic acid, polyoxyethylene alkyl ether carboxylic acid, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether propionic acid, and These salts can be mentioned.

As cationic surfactant, a quaternary ammonium salt type surfactant or an alkyl pyridium type surfactant is mentioned.

As an amphoteric surfactant, a betaine type surfactant, an amino acid type surfactant, an imidazoline type surfactant, and an amine oxide type surfactant are mentioned.

Content of surfactant in etching liquid becomes like this. Preferably it is 0.0001-5 mass% with respect to the total mass of etching liquid, More preferably, it is 0.0001-1 mass%. It is preferable because the viscosity of the cleaning composition can be adjusted and the wettability to the cleaning object can be improved by adding the surfactant to the cleaning composition, and it is also preferable that both of the corrosiveness to the substrate, the insulating film, and the like are more excellent. Such surfactants are generally commercially available. You may use these surfactant individually or in combination of 2 or more.

(Aqueous medium)

It is preferable that the etching liquid of this embodiment is an aqueous liquid composition which uses an aqueous medium as a medium. An aqueous medium means water and the aqueous solution which melt | dissolved the solute soluble in water. As a solute, the salt of an alcohol or an inorganic compound is mentioned, for example. However, even when the solute is applied, the amount is preferably suppressed in the range in which the desired effect is exerted. In addition, the said aqueous composition means that an aqueous medium becomes a main medium, It is preferable that more than half of media other than solid content is an aqueous medium, 70 mass% or more is more preferable, It is especially preferable that it is 90 mass% or more.

In addition, in this specification, a semiconductor substrate is used by the meaning containing not only a wafer but the whole board | substrate structure in which the circuit structure was given. A semiconductor substrate member refers to the member which comprises the semiconductor substrate defined above, and may consist of one material, or may consist of several material. Moreover, the processed semiconductor substrate may be distinguished and called as a semiconductor substrate product, and the chip | tip and the processed product which further processed and dicing and pulled out this as needed are called a semiconductor element.

In addition, although the upper and lower limits of a semiconductor substrate do not need to be determined in particular, based on what was shown in this specification, the side of the wafer 3 is made into the lower (bottom) direction, and the side of the conductive film 5 is made into the upper part (thousand). In the direction of.

(Kit)

The etching liquid of this invention consists of agent A and agent B, and the kit which mixes agent A and agent B just before use may be sufficient. In this case, the structure etc. which ammonia is contained in agent A, and certain basic compounds, such as tetramethylammonium hydroxide, are contained in agent B are mentioned, for example. This division into two kits is preferable from the viewpoint of manufacturing cost.

In this embodiment, only one agent may be drawn during the chemical liquid circulation of the sheet processing apparatus. By doing this, a high etching rate is realized longer.

[Etching Condition]

Although the conditions which etch in this embodiment are not specifically limited, Etching of a spray type | mold or wafer spin type | mold (sheet type | mold) or batch type (immersion type | mold) may be sufficient. In the spray type (wafer fin type) etching, the semiconductor substrate is conveyed or rotated in a predetermined direction, the etching liquid is injected into the space, and the etching liquid is brought into contact with the semiconductor substrate. On the other hand, in a batch etching, a semiconductor substrate is immersed in the liquid bath which consists of etching liquid, and a semiconductor substrate and an etching liquid are made to contact in the said liquid bath. These etching methods may be appropriately used according to the structure, material, and the like of the device.

In the case of the wafer spin type, the etching temperature is preferably set to an injection space of 15 to 100 ° C, more preferably 20 to 80 ° C. As for etching liquid, it is preferable to set it as 20-100 degreeC, It is more preferable to set it as 30-95 degreeC, It is especially preferable to set it as 50-90 degreeC. By carrying out more than the said lower limit, sufficient etching rate with respect to a metal layer can be ensured, and it is preferable. It is preferable because the selectivity of etching can be ensured by using below the said upper limit. Although the supply rate of an etching liquid is not specifically limited, It is preferable to set it as 0.05-2 L / min, and it is more preferable to set it as 0.1-1 L / min. It is preferable because the in-plane uniformity of etching can be ensured by using more than the said lower limit. By setting it as the said upper limit or less, stable selectivity can be ensured at the time of continuous processing, and it is preferable. When rotating a semiconductor substrate, it is based also on the magnitude | size etc., but from a viewpoint similar to the above, it is preferable to rotate at 0-500 rpm, and to rotate at 10-400 rpm.

In the case of a batch type, it is preferable to make liquid bath 15-90 degreeC, and it is more preferable to set it as 20-80 degreeC. By setting it as the said lower limit or more, an etching rate can be ensured and it is preferable. It is preferable because the selectivity of etching can be ensured by using below the said upper limit. Although the immersion time of a semiconductor substrate is not specifically limited, It is preferable to set it as 0.5 to 30 minutes, and it is more preferable to set it as 1 to 10 minutes. It is preferable because the in-plane uniformity of etching can be ensured by using more than the said lower limit. By setting it as the said upper limit or less, stable selectivity can be ensured at the time of continuous processing, and it is preferable.

In this invention, it is preferable to etch by the sheet type processing apparatus, and etching is performed one by one, and the etching liquid circulated is discharged and used sequentially. In the present invention, the single-leaf type is preferable because the life of the etching liquid is long and the etching performance is low during circulation. The treatment temperature is preferably the above conditions. In addition, the above conditions are preferable for the processing rotation speed. The treatment may be either spin cleaning or paddle cleaning. Rinse, water, IPA (isopropyl alcohol), perfluoroether, etc. can be mentioned, A suitable process can be selected.

Workpiece

The material to be etched by applying the etching solution of the present embodiment may be any one, but polycrystalline silicon or amorphous silicon may be used as a substrate material used for the production of a general capacitor. On the other hand, the electrode material constituting the core of the capacitor structure is titanium nitride (TiN). That is, it is preferable that the etching liquid of this embodiment has a large ratio (ERs / ERe) of the etching rate (ERs) of the said substrate material and the etching rate (ERe) of an electrode material. Although the value of a specific ratio depends also on a kind of material and a structure, It does not specifically limit, It is preferable that ERs / ERe is 100 or more, and it is preferable that it is 200 or more. Although an upper limit is not specifically limited, It is practical that it is 100,000 or less.

In addition, in this specification, using an etching liquid so that a semiconductor substrate may be etched is called "application", The embodiment is not specifically limited. For example, you may immerse and etch by a batch type, and you may etch by discharge of a single | leaf type thing.

Although the shape and the dimension of the capacitor structure to be processed are not particularly limited, it is preferable to have a cylinder structure as described above, especially when the aspect ratio of the cylinder hole is 5 or more, in which the high effect of the etching solution of the present embodiment is utilized. It is preferable that aspect ratio is 10 or more from a similar viewpoint, and it is more preferable that it is 20 or more. Although there is no upper limit in particular, it is practical that it is aspect ratio 1000 or less. Although the opening diameter d _c of a cylinder hole is not specifically limited, It is preferable that it is 20-80 nm in view of the miniaturization of the capacitor structure of the present invention by the effect exhibited in this embodiment. In the present specification, the trench or its structure is not particularly limited as long as it shows a concave shape in a specific cross section, and not only the groove shape, but also the periphery of the hole shape, and conversely, a large portion of the needle-shaped structure is protruded. Etc. may be sufficient. 3, the cylinder hole Kc corresponds to a hole-shaped trench structure in the trench structure which the recessed part Kd protrudes around many needle-shaped structure parts. The aspect ratio is a value obtained by dividing the depth h ₂ of the concave portion by the width d _c with respect to the cylinder hole Kc. The aspect ratio of the concave portion Kd circumferentially protruding from a large number of needle-shaped structure portions is, for example, a value obtained by dividing the depth h ₁ of the concave portion by the width d _d .

In view of the above, it is preferable that the etching solution of the present invention is performed with respect to the polycrystalline silicon film or the amorphous silicon film while leaving the electrode film made of TiN, Ti, or W at least on the wall surface of the uneven structure. Further, a semiconductor substrate having a substantially flat surface having the polycrystalline silicon film or the amorphous silicon film is prepared, and the etching solution is applied to the surface of the semiconductor substrate to remove the polycrystalline silicon film or the amorphous silicon film, and the removed portion is concave. It is preferable to perform a process which uses a capacitor as the convex part left in the board | substrate. At this time, it is more preferable that a TiN film remains on the wall surface of the concave portion.

The process requirements by the manufacturing method of a preferable semiconductor substrate product in this invention are described below.

(1) A step of preparing a semiconductor substrate having a silicon film made of a polycrystalline silicon film or an amorphous silicon film, and a step of etching at least a portion of the silicon film by applying a specific etching solution to the semiconductor substrate.

(2) In the step of preparing the semiconductor substrate, a multilayer film structure including the silicon film is formed, and irregularities are formed on the semiconductor substrate.

Forming a conductive film on at least an upper surface and a recessed wall surface of the uneven surface;

Providing a buried film on the conductive film to fill the recess with the buried film;

And removing a portion of the conductive film and a portion of the buried film provided on the upper surface to expose the silicon film of the semiconductor substrate.

In the etching process of the silicon film, the etching liquid is applied to the semiconductor substrate to remove the exposed silicon film and the buried film while leaving the conductive film on the wall surface of the recess.

(3) A semiconductor substrate having a substantially flat surface is prepared, the etching liquid is applied to the surface of the semiconductor substrate to remove the silicon film and the buried film, and the removed portion is a recessed portion. The convex part containing a film | membrane is made into the electrode of a capacitor.

According to the preferable etching method of the said invention, since the residue of the dry etching and ashing performed previously can be removed effectively, it is preferable. Thereby, wet etching of silicon and washing of residue can be performed at once, and contribute to the significant improvement of manufacturing efficiency.

In the manufacturing process of a semiconductor element, there exists a process of etching the metal layer etc. on a semiconductor substrate by plasma etching which used the resist pattern etc. as a mask. Specifically, the metal layer, the semiconductor layer, the insulating layer and the like are etched to pattern the metal layer and the semiconductor layer, or the openings such as via holes and wiring grooves are formed in the insulating layer. In the said plasma etching, the residue used from the resist used as a mask, the metal layer to be etched, a semiconductor layer, and an insulating layer arises on a semiconductor substrate. In the present invention, the residue thus generated by plasma etching is referred to as "plasma etching residue".

In addition, the resist pattern used as a mask is removed after etching. As described above, a wet method using a stripper solution or a dry method by ashing using, for example, plasma or ozone is used to remove the resist pattern. In the ashing, residues deteriorated by the plasma etching residue generated by plasma etching, or residues derived from the resist to be removed, are generated on the semiconductor substrate. In the present invention, the residue produced by ashing is referred to as "ashing residue". In addition, as a generic name of what should be cleaned and removed on the semiconductor substrate through the treatment of plasma etching residue and ashing residue, etc., it may only be called "residue."

It is preferable that the plasma etching residue or ashing residue, which is a residue after such etching, is washed away using a cleaning composition. The etching liquid of this embodiment is applicable also as a washing | cleaning liquid for removing a plasma etching residue and / or an ashing residue. Especially, it is preferable to use in order to remove a plasma etching residue and an ashing residue after the plasma ashing performed following plasma etching.

(Example)

<Example 1, Comparative Example 1>

It contained in the composition (mass%) shown to the component shown in the following Table 1, and the following prescription, and the etching liquid was prepared.

<Etching test>

Test wafer: a capacitor height (corresponding to h ₁ in Fig. 3) is prepared the test pattern wafer for forming an amorphous silicon 6000Å crowned DRAM structure. About this, the sheet | leaf type apparatus (made by SPPS-Europe BV company, POLOS (brand name)) was etched, rinsed with pure water, and dried on condition of the following, and evaluated by the etching rate after 0 minutes and 60 minutes of etching start. . In this apparatus, the etching liquid is circulated in the apparatus, which means that the liquid temperature is maintained at the temperature below the time.

Etching condition

Chemical temperature: 80 ° C

Tank capacity: 40L

Discharge amount: 1 L / min.

Wafer rotation speed 500rpm

Rinse (Pure) Condition

Rinse temperature: Room temperature (25 ° C)

Discharge amount: 1 L / min

Wafer rotation speed 500rpm

Drying conditions

Wafer speed 2000rpm

c17: Corresponds to Example 1 of Japanese Patent Laid-Open No. 2006-351813

c18: Corresponds to Example 1 of Japanese Patent No. 3,994,992

TMAH: Tetramethylammonium hydroxide (tetramethylammonium hydroxide)

HA: Hydroxylamine (hydroxylamine)

MEA: Monoethanolamine (monoethanolamine)

Initial stage: Silicon etching rate (Å / min.) At the start of processing

Time-lapse: Silicon etching rate (m / min.) After 60 minutes

As shown in the above table, according to the silicon etching solution of the present invention, it can be seen that a sufficient etching rate is achieved corresponding to amorphous silicon, and that the etching rate is very low after 60 minutes has elapsed. The silicon etching solution of the present invention, the damage of each layer such as the electrode material of the device TiN, SiN, SiO ₂ was confirmed to be very small.

Moreover, test No. of the comparative example 1 In c11, the speed fall was remarkably large, and c12-c18 had the result that there was no slowdown but the etching rate was not enough.

Moreover, as a result of evaluating the residue of silicon | silicone, each Example brought a result with few residue compared with a comparative example.

<Example 2>

The wafer was replaced with a test pattern wafer using polycrystalline silicon, and the same evaluation as in Example 1 was carried out. As a result, in the silicon etching solution of the present invention, all were 7000 to 14000 dl / min. Sufficient etching rate of the degree was realized, and the decrease of the etching rate after 60 minutes was very small.

<Example 3>

Etching liquid consisting of the following agent A and agent B was prepared, and the same evaluation was performed as in Example 1 by mixing agent A and agent B immediately before use, and a sufficient etching rate was realized at 6000 mW / min. Etching rate was 5000 Pa / min. And there was very little fall of etching rate.

(Product A)

15 mass% of ammonia

Water balance

(Product B)

10% by mass of tetramethylammonium hydroxide

Water balance

1: first insulating film 2: second insulating film
3: silicon wafer 4: photoresist
5: conductive film 6: buried film
7: protection part 9: capacitive insulating film
10: capacitor structure 50: lower electrode (cylinder wall)

Claims (20)

A silicon etching solution containing a combination of ammonia, at least one specific basic compound selected from the group consisting of a hydroxylamine compound, a basic organic compound, and a metal-containing basic compound is applied to the polycrystalline silicon film or the amorphous silicon film, thereby applying the polycrystalline silicon. And removing at least a portion of the film or the amorphous silicon film to form a concave-convex shape serving as a capacitor. The method of claim 1,
And the specific basic compound is at least one member selected from the group consisting of tetramethylammonium hydroxide, potassium hydroxide, hydroxylamine compound and alkanolamine. 3. The method according to claim 1 or 2,
_A content ratio (M _A / M _SB ) between the mass (M _A ) of the ammonia and the mass (M _SB ) of the specific basic compound is 0.1 to 10, wherein the capacitor structure is formed. 3. The method according to claim 1 or 2,
The concentration of the said ammonia is 5-25 mass%, The formation method of the capacitor structure characterized by the above-mentioned. 3. The method according to claim 1 or 2,
The concentration of the said specific basic compound is 1-25 mass%, The formation method of the capacitor structure characterized by the above-mentioned. 3. The method according to claim 1 or 2,
A method of forming a capacitor structure, wherein at least a part of the polycrystalline silicon film or the amorphous silicon film is removed by a sheet processing apparatus. 3. The method according to claim 1 or 2,
The etching solution comprises the agent A comprising the ammonia and the agent B comprising the specific basic compound, and the agent A and the agent B are mixed during use. 3. The method according to claim 1 or 2,
The concave-convex portion constituting the capacitor structure comprises TiN. 3. The method according to claim 1 or 2,
And forming at least a portion of the polycrystalline silicon film or the amorphous silicon film by the silicon etching solution to form a trench structure having an aspect ratio (depth / opening width) of 10 or more. 3. The method according to claim 1 or 2,
And etching the polycrystalline silicon film or the amorphous silicon film while leaving an electrode film made of TiN, Ti, or W at least on the wall surface of the uneven structure. 3. The method according to claim 1 or 2,
A semiconductor substrate having a substantially flat surface having the polycrystalline silicon film or the amorphous silicon film is prepared, and the etching solution is applied to a surface of the semiconductor substrate to remove the polycrystalline silicon film or the amorphous silicon film, and the removed portion is concave. And a convex portion left in the substrate as a lower electrode of the capacitor. The method of claim 11,
And the convex portion is made of TiN. Etching liquid for forming a capacitor structure by forming at least part of a polycrystalline silicon film or an amorphous silicon film to form a concave-convex shape serving as a capacitor: selected from the group consisting of ammonia, a hydroxylamine compound, a basic organic compound, and a metal-containing basic compound A silicon etchant comprising a combination of at least one specific basic compound. The method of claim 13,
Said specific basic compound is at least 1 sort (s) chosen from the group which consists of tetramethylammonium hydroxide, potassium hydroxide, a hydroxylamine compound, and an alkanolamine. The method according to claim 13 or 14,
The mass ratio of content of the said ammonia and the said specific basic compound is 0.1-10, The silicon etching liquid characterized by the above-mentioned. The method according to claim 13 or 14,
The concentration of said ammonia is 5-25 mass%, The silicon etching liquid characterized by the above-mentioned. The method according to claim 13 or 14,
The concentration of the said specific basic compound is 1-25 mass%, The silicon etching liquid characterized by the above-mentioned. The method according to claim 13 or 14,
Silicon etching liquid used in a single wafer processing apparatus. The method according to claim 13 or 14,
A silicon etching solution comprising the agent A containing the ammonia and the agent B containing the specific basic compound, wherein both kits are mixed and used at the time of use. The method according to claim 13 or 14,
The uneven part constituting the capacitor structure comprises TiN.

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