JP5439466B2 - Silicon etching method, silicon etching solution used therefor, and kit thereof - Google Patents

Description

  The present invention relates to a silicon etching method, a silicon etching solution used therefor, and a kit thereof.

  Conventionally, a concave type has been adopted as a capacitor structure of a DRAM. In this structure, the lower electrode film is formed in the cylinder hole, and only the inner side surface functions as an electrode. According to this, the area occupied by the capacitor can surely be reduced, but the diameter of the cylinder hole is inevitably reduced. On the other hand, the capacity required for the device operation of the DRAM must be secured. In order to satisfy both of these requirements, the depth of the cylinder hole is becoming deeper and it is becoming difficult to cope with the fine processing technology.

  Although efforts have been made to reduce the aspect ratio of the capacitor structure, it is not easy in itself to form a fine cylinder structure and its holes with high precision. Usually, this processing is performed by wet etching. That is, the inner and outer members must be removed by the etching solution so that a cylindrical structure having a cylinder wall having a depth of nanometer to submicrometer size is left on the semiconductor substrate. In particular, the removal of the inside of the cylinder hole must be removed so as to remove the material from the enclosed space, which is difficult as a process performed by wet etching.

  A treatment liquid that has an alkali compound as a main component has been proposed as a treatment liquid exhibiting etching properties with respect to single crystal silicon (see Patent Documents 1 and 2, etc.). Further, an acidic wet etching solution in which a specific surfactant is combined with hydrogen fluoride and ammonium fluoride is disclosed (Patent Document 3). Thereby, the wettability and the defoaming property in the wet process are improved.

JP 2006-351813 A JP 2006-054363 A JP 2002-069674 A

In addition to the capacitor structures that have been adopted recently, the etching solution that enables good removal of silicon in a complicated form has not yet been fully researched and developed. In particular, the present inventors considered that it is important to remove silicon accurately and at high speed from the viewpoint of improvement of manufacturing quality when an element is formed. In particular, studies have been conducted on the etching properties of polycrystalline silicon and / or amorphous silicon whose use has been expanding in recent years.
Then, in the etching of the polycrystalline silicon and / or amorphous silicon, a residue may remain after the processing, and it has been found that this countermeasure is necessary. This phenomenon becomes more prominent as the aspect ratio becomes higher in the capacitor structure and the like. This is thought to be because the convection of the chemical solution is stagnated in the concave portion, and the residue tends to remain at the root.
In view of the above technical problem in the field, the present invention provides a silicon etching solution capable of accurately and rapidly removing polycrystalline silicon and / or amorphous silicon, and suppressing or preventing the generation of residues, and a silicon etching solution therefor. An object of the present invention is to provide an etching method used and a method for manufacturing a semiconductor substrate product using the etching method.

The present inventor prepared chemical solutions of various prescriptions for the etching properties of the polycrystalline silicon and the amorphous silicon, and analyzed the behavior thereof. As a result, it has been found that the etching rate and the residue suppression do not always agree with each other, and it is not easy to satisfy both at a high level. Therefore, through the test evaluation and analysis, the etching rate and the residue can be suppressed / prevented only under the limited condition that an alkali compound, an oxidizing agent, and a hydrofluoric acid compound are contained in water and the pH is adjusted to 10 or more. I found out that it is possible to achieve both.
The present invention has been completed based on such findings.

(1) a step of preparing a silicon etching solution having a pH of 10 or higher containing an alkali compound, an oxidizing agent, a hydrofluoric acid compound, and water, and applying the silicon etching solution to a polycrystalline silicon film or an amorphous silicon film, A silicon etching method including a step of removing a part.
(2) The silicon etching method according to (1), wherein the alkali compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.
(3) The oxidizing agent is at least one selected from hydrogen peroxide, nitric acid and its salt, nitrite, periodic acid and its salt, and perchloric acid and its salt, as described in (1) or (2) Silicon etching method.
(4) The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride (1 The silicon etching method according to any one of (1) to (3).
(5) The silicon etching method according to any one of (1) to (4), wherein an uneven shape to be a capacitor is formed by removing a part or all of the polycrystalline silicon film or the amorphous silicon film.
(6) The silicon etching method according to (5), wherein a cylinder structure in which an aspect ratio of the concavo-convex shape portion is 15 to 100 is formed.
(7) A method for manufacturing a semiconductor substrate product, wherein the semiconductor substrate is processed using the silicon etching method according to any one of (1) to (6).
(8) 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 part of the silicon film by applying the etching solution to the semiconductor substrate. The manufacturing method of the semiconductor substrate product as described in (7).
(9) An etching solution for removing a part or all of a polycrystalline silicon film or an amorphous silicon film, which contains an alkali compound, an oxidizing agent, a hydrofluoric acid compound, and water and has a pH of 10 or more liquid.
(10) The silicon etching solution according to (9), wherein the alkali compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.
(11) In the above (9) or (10), the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid and salts thereof, nitrite, periodic acid and salts thereof, and perchloric acid and salts thereof. The silicon etching liquid as described.
(12) The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride (9 The silicon etching solution according to any one of (11) to (11).
(13) 3 to 25% by mass of the alkali compound, 0.01 to 20% by mass of the hydrofluoric acid compound, and 0.001 to 5% by mass of the oxidizing agent (9) to (12) The silicon etching liquid of any one of these.
(14) The silicon etching solution according to any one of (9) to (13), further containing a hydroxylamine compound.
(15) A kit for a silicon etching solution comprising at least a first liquid and a second liquid, and using a mixture thereof, the etching liquid for removing a part or all of a polycrystalline silicon film or an amorphous silicon film And
The first liquid contains an alkali compound and water, the second liquid is an acidic aqueous solution, and an oxidizing agent and a hydrofluoric acid compound are contained in the first liquid, the second liquid, or other liquid, respectively. A kit for a silicon etching solution in which each solution is prepared so that the pH becomes 10 or more when the solutions are mixed to form an etching solution.
(16) The kit for silicon etching liquid according to (15), wherein the second liquid contains a hydroxylamine compound.
(17) The kit for silicon etching liquid according to (15) or (16), wherein the alkali compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.
(18) Any of (15) to (17), wherein the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid and its salt, nitrite, periodic acid and its salt, and perchloric acid and its salt A kit for a silicon etching solution according to claim 1.
(19) The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride (15 ) To (18) The kit for silicon etching liquid according to any one of the above.
(20) The kit for silicon etching solution according to any one of (15) to (19), wherein the pH of the second solution is 3 to 6.

  According to the present invention, polycrystalline silicon and / or amorphous silicon can be removed accurately and at high speed, and the generation of residues can be suppressed or prevented. Furthermore, if necessary, it can be applied to a capacitor structure composed of electrodes having a cylinder structure, and the polycrystalline silicon film and / or the amorphous silicon film can be efficiently removed without generating excessive residues. It has an excellent effect of being able to.

It is sectional drawing which shows typically the example of a manufacturing process of the capacitor structure applied to this invention. It is sectional drawing which shows typically the example of a manufacturing process of the capacitor structure applied to this invention (continuation of FIG. 1). It is sectional drawing which shows typically the example of a manufacturing process of the capacitor structure applied to this invention (continuation of FIG. 2). FIG. 4 is a cross-sectional view schematically showing a manufacturing process example of a capacitor structure applied to the present invention (continuation of FIG. 3). It is sectional drawing which shows typically another example of the capacitor structure applied to this invention. It is sectional drawing which shows typically the example of a manufacturing process of the capacitor structure applied to this invention. It is a plane sectional view of the capacitor structure applied to the present invention.

[Formation of capacitor structure]
First, before describing the etching solution according to the present invention, a manufacturing example of a capacitor structure that can be suitably employed in the present invention will be described with reference to the accompanying drawings. In the following detailed description, the formation of the capacitor structure will be mainly described, but the present invention is not construed as being limited thereto.

(Process 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 first molding film 1 is an etching stopper film when the cylinder hole is opened, and is a film having an etching rate ratio with the second molding film 2 by an anisotropic dry etching process. Examples of the first molded film 1 include a nitride film formed by an LP-CVD (Low-Pressure Chemical Vapor Deposition) process. On the other hand, in the present embodiment, a polycrystalline silicon film or an amorphous silicon film is employed as the second molding film 2. Further, although not shown, a protective film may be provided.
Although the silicon wafer 3 is greatly simplified and shown as a single layer, a predetermined circuit structure is usually formed here. For example, those using an isolation insulating film, gate oxide film, gate electrode, diffusion layer region, polysilicon plug, silicon oxide film, silicon nitride film, bit line, metal plug, nitride film, plasma oxide film, BPSG film, etc. (For example, refer to Patent Document 1). Moreover, in FIGS. 1-6, although it does not show in particular with hatching, the cross section of each member is shown.

(Process b)
Next, after patterning the photoresist 4 using a photolithography process, holes are formed by anisotropic dry etching (concave portion Ka). As for the photoresist 4 and the dry etching method at this time, a normal object or method applied to this type of product may be applied.

(Process c), (Process d)
Furthermore, after opening, along the wall surface Wa of the recess Ka and the upper surface Wb of the molding film (silicon film) 2, the conductive film 5 made of TiN and the embedded film 6 for protecting the conductive film 5 (for example, polycrystalline silicon or amorphous A silicon film is sequentially formed. At this time, a recess formed intermediately (after formation of the conductive film 5) is shown as Kb.

(Process e) (Process f)
After the buried 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 CMP (Chemical Mechanical Polishing), and the etch back line E is exposed. Here, the second molding film 2 and the embedded film 6 are removed by wet etching. In the present invention, this step is important, and an etching solution according to the present invention described later exhibits a high effect. Through this step, the lower electrode (cylinder wall) 50 (FIG. 3) of the capacitor having the cylinder hole Kc is formed. The depth h ₂ of the cylinder bore wall is not particularly limited, considering the conventional construction of such a device, it is practical that a 500-2000 nm. Note that the etching solution of the present invention is preferably applied to the surface smoothed by the etch back or the like as described above, and it is preferable that the buried film is removed therefrom to form a trench structure.

(Process g)
After the formation of the lower electrode 50 of the capacitor formed as described above, the capacitor insulating film 9 is formed, and then the plate electrode (upper electrode) (not shown) is sequentially formed to form the capacitor structure 10. In this specification, the capacitor structure may be a capacitor itself or a structure part constituting a part of the capacitor. In the example shown in FIG. 4, the lower electrode 50, the capacitor insulating film 9, The capacitor structure 10 is shown as comprising. In the figure, the lower electrode 50 and the wafer 3 are shown as being separated from each other by the molding film 1. However, if necessary, the lower electrode 50 and the wafer 3 are electrically connected at the cross section or at different positions in the figure. May be interpreted as For example, a plug structure or damascene structure may be formed in the molding film 1 to ensure conduction, or the lower electrode 50 may be formed so as to penetrate the molding film 1. Further, the capacitor insulating film 9 may be formed not only on the lower electrode 50 but also on other substrate surfaces.

FIG. 5 shows a modification of the capacitor structure of the above embodiment. In this example, the bottom 81 and the main part 82 of the lower electrode (cylinder structure) are made of different materials. For example, the bottom 81 is made of Si ₃ N ₄ and the main part 82 is made of TiN.

(Process a ')
FIG. 6 shows a modification of the manufacturing example of the above embodiment. A first molding film 1, a second molding film 2, a third molding film 21 and a fourth molding film 31 are sequentially formed on the silicon wafer 3. The first molding film 1 is an etching stopper film when the cylinder hole is opened, and the second molding film 2 is a film having an etching rate ratio in an anisotropic dry etching process. Examples of the first molded film 1 include a nitride film formed by an LP-CVD process. The second molded film 2, the third molded film 21, and the fourth molded film 31 have a combination of films that do not have an etching rate ratio by anisotropic dry etching and can obtain an etching rate ratio by isotropic etching. Further, it is preferable to form the second molding film 2, the third molding film 21, and the fourth molding film 31 with a film that can be removed at once with the same wet etching solution at the time of capacitor formation.
The etching rate ratio in the isotropic etching is such that the second molding film 2 and the fourth molding film 31 have the same etching rate, and the third molding film 21 has the second molding film 2 and the fourth molding film 21. It is preferable that the film has a larger etching rate than that of the molded film 31. Further, the second molding film 2 and the fourth molding film 31 may be the same film or different films. Further, although not shown, a protective film may be provided. The silicon wafer 3 is greatly simplified and shown as a single layer, but as described above, a predetermined circuit structure is usually formed here. Further, in FIG. 6, although not particularly shown with hatching, the cross-section of each member is shown, and in FIG. 7, a flat cross-sectional view is shown with hatching.

(Process b ')
Next, after patterning the photoresist 4 using a photolithography process, holes are formed by anisotropic dry etching (concave portion Ka). As for the photoresist 4 and the dry etching method at this time, a normal object or method applied to this type of product may be applied.
After the opening, isotropic etching is performed to form the recess Va in the portion of the third molding film 21, and then the electrode protection film 7 is grown. The electrode protective film 7 is a molded film having a sufficient etching rate ratio with respect to the etching solution used for removing the second molded film 2, the third molded film 21, and the fourth molded film 31 at the time of capacitor formation. Further, it is preferable that the film can be formed uniformly over the entire recess Ka, and the recess 7 formed in the middle of the recess Ka can be completely embedded. Examples thereof include a nitride film using an ALD (Atomic Layer Deposition) method and a tantalum pentoxide (Ta ₂ O ₅ ) film.
After the growth of the electrode protective film 7, the electrode protective film 7 is removed by etching. At this time, the electrode protective film 7 in the recess Va remains without being removed.

(Process c ')
Similar to the above steps (c) to (g), the lower electrode (cylinder wall) 50 of the capacitor having the cylinder hole Kc is formed. In the same manner as in the above manufacturing example, after the capacitor lower electrode 50 is formed, the capacitor insulating film 9 is formed, and then the plate electrode (upper electrode) (not shown) is sequentially formed to form the capacitor structure. In this specification, the capacitor structure may be a capacitor itself or a structure part constituting a part of the capacitor.

[Silicon etchant]
Next, a preferred embodiment of the silicon etching solution of the present invention that can be used extremely effectively for the wet etching described in the above steps e and f will be described. The etching liquid of this embodiment contains an alkali compound, an oxidizing agent, a hydrofluoric acid compound, and water, and the pH is adjusted to 10 or more. This makes it possible to remove the polycrystalline silicon film or the amorphous silicon film related to the formation of the capacitor structure having the uneven shape as described above accurately and at a high speed, while suppressing and preventing the residue. The reason for this special effect is not clear, but it is as follows when including the estimation. Usually, an alkaline etching solution oxidizes Si to form Si (OH) ₄ and dissolves it. In the present invention, in addition to the scheme, it is considered that the fluorine ion (F ⁻ ) of the hydrofluoric acid compound acts to form a soluble compound of Si. Further, when a hydroxylamine compound is used, it can be expected that this forms a complex with Si and promotes dissolution. That is, in the present invention, it is considered that a plurality of dissolution routes promotes the solubility of Si, which cannot be achieved simply by adding alkali, due to the interaction or synergistic effect. In particular, according to the present invention, a polycrystalline silicon film or an amorphous silicon film having a high aspect ratio as shown in FIGS. 3 and 6 and a deep cylinder hole Kc or a complicated etching shape such as Kd in FIG. Can be accurately removed.

(Alkali compounds)
The etching liquid of this embodiment contains an alkali compound. The alkaline compound may be interpreted as the ordinary meaning of the word, but refers to all compounds that have an action of increasing the pH in the system in water.

When the alkali compound is an organic compound, the number of carbon atoms is preferably 4 to 30, and more preferably 6 to 16 from the viewpoint of boiling point or solubility in water.
The organic amine used as the organic alkali compound of the etching solution of the present embodiment includes monoethanolamine, diethanolamine, triethanolamine, diethylene glycolamine, alkanolamines such as N-hydroxylethylpiperazine, and / or ethylamine, benzylamine, Diethylamine, n-butylamine, 3-methoxypropylamine, tert-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, o-xylenediamine, m-xylylenediamine, 1-methylbutylamine, Ethylenediamine (EDA), 1,3-propanediamine, 2-aminobenzylamine, N-benzylethylenediamine, diethylenetriamine, triethylenetetramine, etc. It includes organic amine having no hydroxy group. From the viewpoint of preventing metal corrosion, an organic amine having no hydroxyl group is preferred to an alkanolamine. Further, ethylenediamine, 1,3-propanediamine, o-xylenediamine, and m-xylylenediamine are particularly preferable because they can coordinate with a metal. In addition, in the description of a compound and a group (atomic group) in this specification, the description which does not describe substitution and non-substitution includes what has a substituent with what does not have a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

The quaternary ammonium hydroxide used as the alkali compound is preferably a tetraalkylammonium hydroxide, more preferably a tetraalkylammonium hydroxide substituted with a lower (1 to 4 carbon) alkyl group, specifically, Examples thereof include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH). Furthermore, examples of the quaternary ammonium hydroxide include trimethylhydroxyethylammonium hydroxide (choline), methyltri (hydroxyethyl) ammonium hydroxide, tetra (hydroxyethyl) ammonium hydroxide, and benzyltrimethylammonium hydroxide (BTMAH). In addition, a combination of ammonium hydroxide and one or more quaternary ammonium hydroxides can 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 singly or in combination of two or more.

  Although it does not specifically limit as an inorganic alkali compound, Ammonia, hydrazine, an alkali metal, or its hydroxide is mentioned. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide.

  Speaking without distinguishing between organic and inorganic, the alkali compound is preferably KOH, ammonia or quaternary ammonium hydroxide, more preferably ammonia, TMAH or TBAH, still more preferably TMAH or TBAH, and particularly preferably TMAH.

  The content of the alkali compound is preferably contained in the range of 3 to 25% by mass with respect to the total weight of the etching solution of the present embodiment. Here, more specifically, from the viewpoint of pH adjustment, if it is divided according to the presence or absence of HAS (hydroxylamine sulfate) described later, when this is not present, the alkali compound is further preferably 5 to 25% by mass, and 7 to 25% by mass. More preferred. When HAS is present, it is more preferably 7 to 25% by mass, and particularly preferably 9 to 25% by mass. It is preferable to set it to the above lower limit value or more because a high etching rate can be maintained. In addition, since performance is saturated, it is sufficient to cope with the above upper limit from the viewpoint.

(Hydrofluoric acid compound)
The hydrofluoric acid compound means a compound that generates fluorine ions (F ⁻ ) in the system, and is defined as including hydrofluoric acid (hydrofluoric acid) and a salt thereof. Specifically, hydrofluoric acid, alkali metal fluorides (NaF, KF, etc.), hydrofluoric acid salts of amines (monoethylamine hydrofluoride, triethylamine trihydrofluoride, etc.), pyridine hydrofluoric acid, hydrofluoric acid, ammonium, quaternary alkyl ammonium fluoride (tetramethylammonium fluoride, hydrofluoric tetra -n- _{butylammonium), H 2 SiF 6, HBF} 4, HPF 6 and the like, hydrofluoric acid, alkali metal salts fluoride Ammonium fluoride and quaternary alkyl ammonium fluoride are preferred, hydrofluoric acid, ammonium fluoride and quaternary alkyl ammonium fluoride are more preferred, and quaternary alkyl ammonium fluoride is particularly preferred. Among these, tetramethylammonium fluoride is preferable from the viewpoint of achieving good selectivity.

The hydrofluoric acid compound is preferably contained within a range of 0.01 to 20% by mass, more preferably 0.1 to 20% by mass, based on the total mass of the etching solution of the present embodiment. More preferably, the content is 5 to 15% by mass. It is preferable to set it to the upper limit or less because silicon residues can be suppressed. It is preferable from the viewpoint of etching the silicon layer at a sufficient rate to be not less than the above lower limit.
In addition, in this specification, it uses for the meaning containing the salt, a complex, and its ion besides the said compound itself about the display of a compound. Moreover, it is the meaning including the derivative | guide_body which changed the predetermined part in the range with the desired effect. Furthermore, it is synonymous also with the meaning which may have arbitrary substituents about the compound which does not specify substitution and unsubstituted.

(Oxidant)
In the present invention, the oxidizing agent refers to all substances having an oxidizing action, and those commonly used for that purpose can be used. More specifically, it can be defined as a substance that provides oxygen, a substance that deprives hydrogen, a substance that increases the positive oxidation number, or a substance that deprives electrons comprehensively. Examples of the oxidizing agent preferably used in the present invention include transition metal oxides, peroxides, ammonium cerium nitrate, nitric acid, nitrates, nitrites, iodic acid, iodate, periodic acid, periodate, perchloric acid, Perchlorate, persulfate, persulfate, peracetic acid, peracetate, permanganate compound, dichromate compound, peroxide, nitric acid, nitrate, nitrite, periodic acid, periodic acid Salt, perchloric acid, perchlorate are preferred, hydrogen peroxide, nitric acid, nitrate, nitrite, periodic acid, periodate, perchloric acid, perchlorate are more preferred, nitric acid, nitrate, subchlorate Nitrate is more preferable, and nitric acid and nitrate are more preferable.
Ammonium nitrate is particularly preferred.
Among nitric acid and nitrate, nitric acid, ammonium nitrate, and quaternary alkyl ammonium nitrate are preferable, quaternary alkyl ammonium nitrate is more preferable, and tetramethyl ammonium nitrate is particularly preferable.

Although the content rate of an oxidizing agent is not specifically limited, 0.001-5 mass% is preferable and 0.005-3 mass% is more preferable. By setting it to the above lower limit or higher, a high etching rate can be maintained, which is preferable. By setting it to the upper limit value or less, an increase in silicon residue can be prevented, which is preferable. However, it is preferable that the pH of the etching solution is 10 or more, as with the alkali compound.
In addition, even if it is an oxidizing agent which belongs to the said definition, what belongs to the said alkali compound or a hydrofluoric acid compound shall be defined by the latter, not as an oxidizing agent.

(Hydroxylamine compound)
The etching solution of the present embodiment preferably contains a hydroxylamine compound. As defined for the above-mentioned compounds, the term hydroxylamine compound includes hydroxylammonium ion, hydroxylamine, and / or a salt thereof, and typically means hydroxylamine and / or a salt thereof.

  The hydroxylamine salts used to form the etching solution of the present embodiment include hydroxylamine nitrate (also referred to as HAN), hydroxylamine sulfate (also referred to as HAS), hydroxylamine phosphate, hydroxyl An amine hydrochloride etc. can be illustrated. An organic acid salt of hydroxylamine can also be used for the etchant, and examples include hydroxylamine citrate and hydroxylamine oxalate. Among these salts of hydroxylamine, inorganic acid salts such as hydroxylamine nitrate, hydroxylamine sulfate, hydroxylamine phosphate, and hydroxylamine hydrochloride are preferable because they are inert to metals such as aluminum, copper, and titanium. In particular, hydroxylamine nitrate and hydroxylamine sulfate are preferred. These hydroxylamine compounds can be used singly or in combination of two or more.

  The hydroxylamine compound is preferably contained within a range of 0.1 to 20% by mass, more preferably 5 to 20% by mass, with respect to the total mass of the etching solution of the present embodiment, and 5 to 15%. More preferably, it is contained by mass%. It is preferable to set it to the upper limit value or less because a high etching rate can be maintained. It is preferable from the viewpoint of a silicon residue to set it more than the said lower limit.

(Aqueous medium)
The etching solution of the present invention contains water, but may be an aqueous liquid composition using an aqueous medium as a medium. An aqueous medium refers to an aqueous solution in which water and a water-soluble solute are dissolved. Examples of the solute include salts of alcohols and inorganic compounds other than the essential components. However, even when the solute is applied, it is preferable that the amount is suppressed within a range in which a desired effect is obtained. The aqueous composition means that the aqueous medium is the main medium, and the majority of the medium other than the solid content is preferably the aqueous medium, more preferably 55% by mass or more and 100% by mass or less. 60 mass% or more and 100 mass% or less is particularly preferable.

  In this specification, the term “semiconductor substrate” is used to mean not only a wafer but also the entire substrate structure having a circuit structure formed thereon. 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 materials. A processed semiconductor substrate is sometimes referred to as a semiconductor substrate product, and is further distinguished as necessary, and a chip that has been processed and diced out and processed product thereof is referred to as a semiconductor element. That is, in a broad sense, a semiconductor element belongs to a semiconductor substrate product. A substrate having a capacitor structure is also included in this semiconductor product.

  Note that the upper and lower sides of the semiconductor substrate need not be particularly defined, but in this specification, based on what is illustrated, the side of the wafer 3 is a lower (bottom) direction and the conductive film 5 is an upper ( The direction of the top.

(PH)
The silicon etching solution of the present invention is alkaline and is adjusted to pH 10 or higher. This adjustment can be performed by adjusting the addition amount of the essential components (alkali compound, oxidizing agent, hydrofluoric acid compound). However, it may be adjusted in relation to an arbitrary component (hydroxylamine compound), and may be adjusted to a pH in the above range using another pH adjuster as long as the effects of the present invention are not impaired. The pH of the silicon etching solution is preferably 11 or more, and more preferably 12 or more. When this pH is not more than the above upper limit value, a sufficient etching rate and residue removal can be obtained. There is no particular upper limit to the pH, but it is practical that it is 14 or less. In the present invention, unless otherwise specified, pH is a value measured at room temperature (25 ° C.) with F-51 (trade name) manufactured by HORIBA. Or the value measured according to JISZ8802 pH measurement method may be sufficient. The timing of measurement is not particularly limited, but when it can be changed over time, it is the value measured immediately after preparation (within 5 minutes). Alternatively, the initial pH may be specified by estimating the change with time using a calibration curve or the like.

(Other ingredients)
-Addition of organic solvent In the silicon etching solution of the present invention, a water-soluble organic solvent may be further added. This is effective in that the uniform etching property within the wafer surface can be further improved. Water-soluble organic solvents are alcohols (for example, glycols (ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, propylene glycol, 2-methyl-2,4-pentanediol , Diethylene glycol, dipropylene glycol, dipropylene glycol methyl ether, propylene glycol monopropylene glycol), furfuryl alcohol, glycerin), dimethyl sulfoxide, ethers (eg, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene Glycol dimethyl ether, propylene glycol dimethyl ether) are preferred. The addition amount is preferably 0.1 to 20% by mass, and more preferably 1 to 15% by mass with respect to the total amount of the etching solution. When this amount is not less than the above lower limit, the above-described etching uniformity can be effectively improved. On the other hand, it is possible to ensure wettability with respect to a polycrystalline silicon film, an amorphous silicon film, or other metal film by being below the upper limit.

-Addition of surfactant The silicon etching solution of the present invention may further contain another surfactant. As the surfactant, nonionic surfactants, cationic surfactants, and amphoteric surfactants can be used.

Nonionic surfactants include, for example, polyalkylene oxide alkylphenyl ether surfactants, polyalkylene oxide alkyl ether surfactants, block polymer surfactants composed of polyethylene oxide and polypropylene oxide, and polyoxyalkylene distyrenation. Examples include phenyl ether surfactants, polyalkylene tribenzylphenyl ether surfactants, and acetylene polyalkylene oxide surfactants.
Examples of the cationic surfactant include quaternary ammonium salt surfactants and alkylpyridium surfactants.
Examples of amphoteric surfactants include betaine surfactants, amino acid surfactants, imidazoline surfactants, and amine oxide surfactants.

  The content of the surfactant is preferably 0.0001 to 5% by mass and more preferably 0.001 to 1% by mass with respect to the total mass of the silicon etching solution. It is preferable to add a surfactant to the silicon etchant to adjust the surface tension and contact angle of the silicon etchant and improve the wettability to the etching target. It is also preferable from the point that both properties are more excellent. Such surfactants are generally commercially available. These surfactants may be used alone or in combination.

[kit]
The etching solution of the present invention may be a kit for a silicon etching solution that is composed of at least a first liquid and a second liquid and that is used by mixing them. This etching solution is for removing part or all of the polycrystalline silicon film or the amorphous silicon film. The first liquid includes an alkali compound and water. The second liquid is an acidic aqueous solution. Further, an oxidizing agent and a hydrofluoric acid compound are respectively contained in the first liquid, the second liquid, or other liquids, and each pH is 10 or higher when the liquids are mixed to form an etching liquid. The liquid is being prepared. Preferred ranges such as pH after mixing and the content of each agent are the same as those described in the section of the etching solution.

-1st liquid It is preferable that the 1st liquid contains the alkali compound as mentioned above. Preferred examples of the alkali compound are as described above. Among them, quaternary ammonium hydroxide (TMAH or the like) is preferably used. Preferred combinations of components include an alkali compound alone, a combination of an alkali compound and a hydrofluoric acid compound, or a combination of an alkali compound, a hydrofluoric acid compound and an oxidizing agent. Specific components can be broken down as follows.

(Preferred combination)
A1. Quaternary ammonium hydroxide alone A2. (1) quaternary ammonium hydroxide, and (2) at least one selected from nitric acid, ammonium nitrate, and quaternary alkyl ammonium nitrate A3. (1) quaternary ammonium hydroxide, and (2) at least one selected from hydrofluoric acid, ammonium fluoride, and quaternary alkyl ammonium fluoride A4. (1) quaternary ammonium hydroxide, (2) at least one selected from nitric acid, ammonium nitrate, quaternary alkyl ammonium nitrate, and (3) from hydrofluoric acid, ammonium fluoride, quaternary alkyl ammonium fluoride At least one selected

(More preferred combination)
B1. Quaternary ammonium hydroxide alone B2. At least one selected from (1) quaternary ammonium hydroxide, and (2) ammonium nitrate, quaternary alkyl ammonium nitrate B3. At least one selected from (1) quaternary ammonium hydroxide and (2) ammonium fluoride and quaternary alkyl ammonium fluoride B4. (1) quaternary ammonium hydroxide, (2) at least one selected from ammonium nitrate, quaternary alkyl ammonium nitrate, and (3) at least one selected from ammonium fluoride, quaternary alkyl ammonium fluoride. One

(Especially preferred combination)
C1. Quaternary ammonium hydroxide alone C2. Quaternary ammonium hydroxide and quaternary alkyl ammonium nitrate C3. Quaternary ammonium hydroxide and quaternary alkyl ammonium fluoride C4. Quaternary ammonium hydroxide, quaternary alkyl ammonium nitrate, and quaternary alkyl ammonium fluoride

(Most preferred combination)
D1. Quaternary ammonium hydroxide alone

-Second liquid The second liquid is adjusted to be acidic. The adjustment to acidity includes, for example, the addition of the hydroxylamine compound mentioned as the above optional additive, and among them, the addition of hydroxylamine sulfate is preferable. The second liquid preferably contains the oxidizing agent or the oxidizing agent and hydrofluoric acid compound. The preferred oxidizing agent and hydrofluoric acid compound are the same as described above. Specific components can be broken down as follows.

(Preferred combination)
A1. Hydroxylamine sulfate alone A2. (1) hydroxylamine sulfate, and (2) at least one selected from nitric acid, ammonium nitrate, and quaternary alkyl ammonium nitrate A3. (1) hydroxylamine sulfate, (2) quaternary ammonium hydroxide, and (3) at least one selected from hydrofluoric acid, ammonium fluoride, quaternary alkyl ammonium fluoride A4. (1) hydroxylamine sulfate, (2) quaternary ammonium hydroxide, (3) at least one selected from nitric acid, ammonium nitrate, quaternary alkyl ammonium nitrate, and (4) hydrofluoric acid, ammonium fluoride, At least one selected from quaternary alkyl ammonium fluorides

(More preferred combination)
(1) hydroxylamine sulfate, (2) quaternary ammonium hydroxide, (3) at least one selected from ammonium nitrate, quaternary alkyl ammonium nitrate, and (4) ammonium fluoride, quaternary alkyl ammonium. At least one selected from fluorides

(Especially preferred combination)
Hydroxylamine sulfate, quaternary ammonium hydroxide, quaternary alkyl ammonium nitrate, and quaternary alkyl ammonium fluoride

  In addition, although the said oxidizing agent and a hydrofluoric acid compound can be put into both a 1st liquid and a 2nd liquid, the embodiment which adds these additives to a 2nd liquid is more preferable.

  The preferred pH of the second liquid is 6 or less, more preferably 5 or less. By adjusting the pH to such a range, decomposition of additives such as a hydroxylamine compound is suppressed, and storage stability is improved, which is preferable. Although there is no particular lower limit to this pH, it is practical that it is 1 or more, and 3 or more is preferable as a range that exhibits a better effect. The medium is preferably water for both the first liquid and the second liquid, and an aqueous medium containing a predetermined solute may be used.

(Workpiece)
The shape and dimensions of the capacitor structure to be processed are not particularly limited. However, when the cylinder structure as described above is used, the aspect ratio (h ₂ / d _c ) of the cylinder hole Kc (FIG. 3) is 5 or more. In some cases, the high effect of the etching solution of the present embodiment is utilized, which is preferable. From the same viewpoint, the aspect ratio is preferably 15 or more, and more preferably 20 or more. Although there is no upper limit in particular, it is practical that it is 100 or less. But not limited opening diameter d _c in particular of the cylinder bore Kc, are effective exerted in this embodiment, in consideration of the miniaturization of the recent capacitor structure at the same time, it is preferable in 20 to 80 nm. The distance d _d is not particularly limited between the lower electrode, considering the miniaturization of recent capacitor structure, it is preferable in 20 to 200 nm. The concave and convex shape of the capacitor in the present specification is not particularly limited, but may be a hole shape such as a cylinder (columnar) hole, a quadrangular prism shape, a taper shape, or a reverse taper shape.

Furthermore, from the above viewpoint, in the present invention, at least an electrode film made of a Ti compound (eg, TiN, Ti, etc.), an Hf compound (eg, HfOx, etc.), SiN, or SiO ₂ is left on the wall surface of the concavo-convex structure. However, it is preferable to etch the polycrystalline silicon film or the amorphous silicon film.
Further, a semiconductor substrate having a substantially flat surface having the polycrystalline silicon film or the amorphous silicon film is prepared, and the etching liquid is applied to a surface of the semiconductor substrate, and the polycrystalline silicon film or the amorphous silicon film and It is preferable that the embedded film is removed, the removed portion is a recess, and the protrusion remaining in the substrate is a capacitor. At this time, an electrode film such as TiN is preferably present on the wall surface of the recess.
The etching method of the present invention is not applied only to these manufacturing processes, and can be used for various etching without particular limitation.

(Etching method)
Although it does not specifically limit as an etching apparatus used by this invention, A single wafer type and a batch type can be used. The single wafer method is a method in which wafers are etched one by one. One of the single-wafer embodiments is a method of performing etching by spreading an etching solution over the entire wafer surface with a spin coater. The batch method is a method of etching several to several tens of wafers at a time. One of the batch-type embodiments is a method of etching by immersing a plurality of wafers in a tank filled with an etching solution.
The liquid temperature of the etching liquid, the spray discharge amount of the etching liquid, and the rotation speed of the wafer of the spin coater are selected and used as appropriate values depending on the selection of the wafer to be etched.

  In this embodiment, the etching conditions are not particularly limited, but may be spray (single-wafer) etching or batch (immersion) etching. In spray etching, the semiconductor substrate is conveyed or rotated in a predetermined direction, and an etching solution is sprayed into the space to bring the etching solution into contact with the semiconductor substrate. If necessary, the etching solution may be sprayed while rotating the semiconductor substrate using a spin coater. On the other hand, in batch-type etching, a semiconductor substrate is immersed in a liquid bath made of an etching solution, and the semiconductor substrate and the etching solution are brought into contact in the liquid bath. These etching methods may be properly used depending on the structure and material of the element.

  In the case of a spray type, the environmental temperature at which etching is performed is preferably 15 to 100 ° C., and more preferably 20 to 80 ° C. The etching solution is preferably 20 to 80 ° C., more preferably 30 to 70 ° C. By setting it to the above lower limit value or more, a sufficient etching rate for the metal layer can be secured, which is preferable. By making it not more than the above upper limit value, etching selectivity can be secured, which is preferable. The supply rate of the etching solution is not particularly limited, but is preferably 0.05 to 1 L / min, and more preferably 0.1 to 0.5 L / min. By setting it to the above lower limit value or more, uniformity in the etching plane can be secured, which is preferable. By setting it to the upper limit value or less, it is preferable because stable selectivity can be secured during continuous processing. When the semiconductor substrate is rotated, although it depends on its size and the like, it is preferably rotated at 50 to 400 rpm from the same viewpoint as described above.

  In the case of the batch type, the liquid bath is preferably 20 to 80 ° C, more preferably 30 to 70 ° C. By setting it to the lower limit value or more, the etching rate can be secured, which is preferable. By making it not more than the above upper limit value, etching selectivity can be secured, which is preferable. The immersion time of the semiconductor substrate is not particularly limited, but is preferably 0.5 to 30 minutes, more preferably 1 to 10 minutes. By setting it to the above lower limit value or more, uniformity in the etching plane can be secured, which is preferable. By setting it to the upper limit value or less, it is preferable because stable selectivity can be secured during continuous processing.

In general, examples of the silicon material include single crystal silicon, polycrystalline silicon (polysilicon), and amorphous silicon (amorphous silicon). Of these, polycrystalline silicon or amorphous silicon is used in the present invention.
Single crystal silicon is a silicon crystal in which the orientation of atoms is aligned throughout the crystal, but in reality, various defects exist when observed at the atomic level.
Polycrystalline silicon is block or layered silicon composed of a large number of single crystal grains having different crystal orientations. It may be made of only Si, or may be doped with boron or phosphorus. In addition, various defects and impurities may be present as described above within a range in which a desired effect is achieved. The manufacturing method is not particularly limited, and examples thereof include those formed by a CVD method.
Amorphous silicon refers to an amorphous semiconductor whose constituent element is silicon. Specifically, it is silicon that does not have a long-range periodic structure as described below. It includes those in which some arrangement order is maintained locally, rather than atomic arrangements that are not connected in any disorder. Since the bonds are disordered, the silicon atom loses the covalent bond partner, and there is a dangling bond occupied by electrons not involved in the bond. This dangling bond bonded with hydrogen (hydrogenated) is called hydrogenated amorphous silicon and has a stable solid shape. In this specification, although simply referred to as amorphous silicon, it refers to both cases of non-hydrogenated amorphous silicon and hydrogenated amorphous silicon.

As will be described again, in the present invention, polycrystalline silicon or amorphous silicon is targeted for etching. The meaning is described here.
First, single crystal silicon has surface selectivity and a high etching rate on a specific surface. On the other hand, the etching rate is very slow or not etched on surfaces other than a specific surface. Although there is no such surface selectivity in the etching rate in polycrystalline silicon or amorphous silicon, in general, the etching rate tends to be slower than a specific surface where the etching rate of single crystal silicon is high. The silicon etching solution of the present invention can be etched at high speed even for a polycrystalline silicon film or an amorphous silicon film by an etching mechanism different from that of single crystal silicon.

The process requirements relating to the preferred method for manufacturing a semiconductor substrate product in the present invention are described below.
(1) preparing a semiconductor substrate having a silicon film made of a polycrystalline silicon film or an amorphous silicon film, and applying a specific etching solution to the semiconductor substrate to etch at least a part of the silicon film. .
(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 the upper surface of the irregular surface and the wall surface of the recess;
Providing a buried film on the conductive film and filling the recess with the buried film;
Removing the conductive film portion applied to the upper surface and a part of the embedded film to expose the silicon film of the semiconductor substrate, and
In the silicon film etching step, the etching solution is applied to the semiconductor substrate to remove the exposed silicon film and the embedded 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 solution is applied to the surface of the semiconductor substrate, the silicon film and the embedded film are removed, and the removed portion Is a concave portion, and the convex portion including the conductive film left in the substrate is a capacitor electrode.

<Example 1, comparative example 1>
An etching solution (test solution) having the components and composition (mass%) shown in Table 1 below was prepared.

<Etching test>
Test wafer: A polycrystalline silicon wafer having a thickness of 500 nm formed on single crystal <100> silicon was prepared. On these, etching was performed under the following conditions using a single wafer type apparatus (manufactured by SPS-Europe BV, POLOS (trade name)), and an evaluation test was performed. The cross section of the wafer was photographed with SEM (Scanning Electron Microscope), the remaining film thickness was measured, and the etching rate was obtained.
・ Chemical solution temperature: 80 ℃
・ Discharge rate: 1 L / min.
・ Wafer rotation speed: 500rpm

The etching rate (Rsi) was evaluated according to the following classification.
6:> 1500 nm / min.
5: ≦ 1500,> 1300 nm / min.
4: ≦ 1300,> 1000 nm / min.
3: ≦ 1000,> 800 nm / min.
2: ≦ 800,> 600 nm / min.
1: ≦ 600 nm / min.

The silicon residue was evaluated by observing the etched surface with SEM and visually classifying it as follows.
Out of 100 processed wafers, residual wafers are 6: 1% or less 5: 1% or more 5% or less 4: 5% or more 10% or less 3: 10% or more 15% or less 2: 15% or more 20% or less 1: More than 20%

<Alkali compounds>
TMAH: Tetramethylammonium hydroxide TBAH: Tetrabutylammonium hydroxide

<Oxidizing agent>
H ₂ O ₂ : Hydrogen peroxide HNO ₃ : Nitric acid KNO ₃ : Potassium nitrate NaNO ₃ : Sodium nitrate NH ₄ NO ₃ : Ammonium nitrate KNO ₂ : Potassium nitrite NaClO ₄ : Sodium perchlorate NaIO ₄ : Sodium periodate TMA · NO ₃ : Tetramethylammonium nitrate

<Hydrofluoric acid compound>
HF: Hydrofluoric acid KF: Potassium fluoride NaF: Sodium fluoride NH ₄ F: Ammonium fluoride MEA · HF: Monoethylamine hydrofluoride TEA (HF) ₃ : Triethylamine trihydrofluoric acid TMA · F: Fluorine Tetramethylammonium fluoride TBA · F: tetra-n-butylammonium fluoride HPF ₆ : hexafluorophosphoric acid HBF ₄ : tetrafluoroboric acid H ₂ SiF ₆ : hexafluorosilicic acid

<Accelerator>
HAS: hydroxylamine sulfate

  From the above results, according to the etching solution of the present invention, polycrystalline silicon and / or amorphous silicon can be etched sufficiently industrially, and the excellent effect of suppressing the generation of residues can be exhibited. I understand.

(Example 2)
An etching solution kit A was prepared according to the following formulation.
<First liquid>
TMAH 25% by mass
Water balance <second liquid>
HAS 30% by mass
TMA ・ F 7.5% by mass
TMA ・ NO ₃ 0.5 mass%
Water balance

The first liquid and the second liquid were mixed to prepare a silicon etching liquid. At this time, the mixing ratio (mass ratio) of the first liquid and the second liquid was 6: 4. The shell life comparison test was conducted as follows. Note that the pH of the etching solution after preparation was all> 13.
At this time, the pH of the second liquid was 5.0.

(1) A first liquid and a second liquid were prepared in accordance with the above prescription.
(2) The wafer was immediately etched with the liquid A mixed immediately after preparation (result A). Etching conditions at this time are the same as those in the first embodiment.
(3) On the other hand, liquid A mixed immediately after preparation (corresponding to the case where it was not made into a kit) was stored for 1 month (@ 25 ° C.).
(4) Wafer processing was performed with liquid A after one month (Result B).
(5) After preparing the first liquid and the second liquid, the liquid was allowed to stand for one month. One month later, the first liquid and the second liquid were mixed to perform wafer processing (Result C).
The results A to C are summarized in Table 2 below. From this result, it was found that the performance was as follows: result A = result C> result B. When the etching solution was prepared, the performance tended to deteriorate with time. In other words, it can be seen that the etching solution of the present invention becomes a kit, and the period in which the performance can be maintained becomes longer when the two specific solutions are stored.

  From the above results, it can be seen that all the etching solutions show good performance, but the kits show better performance. This is probably because the shelf life can be increased by using an etching solution kit in which the second solution is acidified.

(Example 3)
In the same manner as in Example 1, the same etching evaluation was performed on the substrate made of amorphous silicon. Thereby, according to the etching liquid of this invention, it confirmed that a high etching rate and the removability of a residue were exhibited also with respect to amorphous silicon.

DESCRIPTION OF SYMBOLS 1 1st shaping | molding film 2 2nd shaping | molding film 3 Silicon wafer 4 Photoresist 5 Conductive film 6 Buried film 7 Electrode protective film 9 Capacitance insulating films 10 and 20 Capacitor structure 21 3rd shaping | molding film 31 4th shaping | molding film 50 Lower electrode (cylinder wall)

Claims (20)

  A step of preparing a silicon etching solution having a pH of 10 or more containing an alkali compound, an oxidant, a hydrofluoric acid compound, and water; and applying the silicon etching solution to a polycrystalline silicon film or an amorphous silicon film to form at least a part of the film. A silicon etching method including a removing step.   The silicon etching method according to claim 1, wherein the alkali compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.   3. The silicon etching method according to claim 1, wherein the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid and a salt thereof, nitrite, periodic acid and a salt thereof, and perchloric acid and a salt thereof.   The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride. The silicon etching method according to any one of the above.   The silicon etching method according to any one of claims 1 to 4, wherein an uneven shape to be a capacitor is formed by removing a part or all of the polycrystalline silicon film or the amorphous silicon film.   The silicon etching method according to claim 5, wherein a cylinder structure having an aspect ratio of 15 to 100 of the uneven shape portion is formed.   The manufacturing method of the semiconductor substrate product which processes a semiconductor substrate using the silicon etching method of any one of Claims 1-6.   8. 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 part of the silicon film by applying the etching solution to the semiconductor substrate. The manufacturing method of the semiconductor substrate product as described in 2.   An etching solution for removing part or all of a polycrystalline silicon film or an amorphous silicon film, which contains an alkali compound, an oxidizing agent, a hydrofluoric acid compound, and water, and has a pH of 10 or more.   The silicon etching solution according to claim 9, wherein the alkali compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.   11. The silicon etching solution according to claim 9, wherein the oxidizing agent is at least one selected from hydrogen peroxide, nitric acid and salts thereof, nitrite, periodic acid and salts thereof, and perchloric acid and salts thereof. .   12. The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride. The silicon etching liquid of any one of these.   The alkali compound is contained in an amount of 3 to 25 mass%, the hydrofluoric acid compound is contained in an amount of 0.01 to 20 mass%, and the oxidizing agent is contained in an amount of 0.001 to 5 mass%. The silicon etching liquid as described in.   Furthermore, the silicon etching liquid of any one of Claims 9-13 which contains a hydroxylamine compound. A kit for a silicon etching solution comprising at least a first liquid and a second liquid and using a mixture thereof, the etching liquid for removing a part or all of a polycrystalline silicon film or an amorphous silicon film. Yes,
The first liquid contains an alkali compound and water, the second liquid is an acidic aqueous solution, and an oxidizing agent and a hydrofluoric acid compound are contained in the first liquid, the second liquid, or other liquid, respectively. A kit for a silicon etching solution in which each solution is prepared so that the pH becomes 10 or more when the solutions are mixed to form an etching solution.   The kit for silicon etching liquid according to claim 15, wherein the second liquid contains a hydroxylamine compound.   The kit for silicon etching liquid according to claim 15 or 16, wherein the alkaline compound is potassium hydroxide, ammonia, or quaternary ammonium hydroxide.   The said oxidizing agent is at least 1 sort (s) chosen from hydrogen peroxide, nitric acid and its salt, nitrite, periodic acid and its salt, and perchloric acid and its salt. Kit for silicon etching solution.   The hydrofluoric acid compound is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium fluoride, amine hydrofluoride, and quaternary alkyl ammonium fluoride. The kit for silicon etching liquids of any one of these.   The kit for silicon etching solution according to any one of claims 15 to 19, wherein the pH of the second solution is 3 to 6.

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