JP2014220300A - Etching liquid, etching method using the same, etching liquid kit, and method for manufacturing semiconductor substrate product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an etching liquid suppressing a silicide layer from being damaged and capable of selectively and appropriately removing a metallic layer disposed on the upper side of the silicide layer, even when germanium is included in the silicide layer; an etching method using the etching liquid; an etching liquid kit; and a method for manufacturing a semiconductor substrate product.SOLUTION: An etching liquid for removing a metallic layer disposed on an upper side of a silicide layer contains: hydrochloric acid; nitric acid; a sulfonic acid compound; a metal corrosion inhibitor that comprises a compound including a heteroatom; and water. The metal corrosion inhibitor is such that a specific nickel solubility ratio of a chemical solution including the metal corrosion inhibitor, to a chemical solution not including the metal corrosion inhibitor is 20% or more.

Description

  The present invention relates to an etching solution, an etching method using the same, an etching solution kit, and a method for manufacturing a semiconductor substrate product.

  Integrated circuit manufacturing is composed of various processing steps in multiple stages. Specifically, in the manufacturing process, deposition of various materials, lithography of a necessary or partially exposed layer, etching of the layer, and the like are repeated many times. Among them, etching of a metal or metal compound layer is an important process. Metal or the like must be selectively etched, and other layers must remain without being corroded. In some cases, it is required to remove only a predetermined layer in a form that leaves layers made of similar metal species or a more highly corrosive layer. The size of wiring and integrated circuits in a semiconductor substrate is becoming increasingly smaller, and the importance of performing etching without being corroded accurately is increasing.

  Taking a field effect transistor as an example, with the rapid miniaturization, there is a strong demand for thinning a silicide layer formed on the upper surface of a source / drain region and for developing a new material. In the salicide process for forming the silicide layer, a part of the source region and the drain region made of silicon or the like formed on the semiconductor substrate and the metal layer attached to the upper surface thereof are annealed. As the metal layer, tungsten (W), titanium (Ti), cobalt (Co), and the like have been applied so far, and recently nickel (Ni) has been adopted. Thereby, a low-resistance silicide layer can be formed on the upper side of the source / drain electrodes and the like. Recently, in response to further miniaturization, it has been proposed to form a NiPt silicide layer to which platinum (Pt), which is a noble metal, is added.

  After the salicide process, the metal layer left there is removed by etching. This etching is usually performed by wet etching, and a mixed solution of hydrochloric acid and nitric acid (aqua regia) is applied as the chemical solution. Patent Document 1 discloses an example using a chemical solution in which toluenesulfonic acid is added in addition to nitric acid and hydrochloric acid.

International Publication No. 2012/125401 Pamphlet

  By the way, recently, further studies have been made on constituent materials such as source / drain electrodes, and application of SiGe epitaxial layers has been proposed. Then, germanium (Ge) is also contained in the silicide layer formed on the upper side. For example, the NiPt silicide layer is configured as a NiPtGe silicide layer containing germanium. Through experiments and analyzes by the present inventors, it has been found that a silicide layer containing germanium (Ge) exhibits a behavior different from that which does not contain a silicide layer, as described above.

  Accordingly, the present invention provides an etching solution capable of suppressing damage to the silicide layer and selectively removing the metal layer disposed on the upper side even when germanium is contained, and an etching method using the same An object is to provide an etching solution kit and a method for manufacturing a semiconductor substrate product. Moreover, while achieving the above-mentioned good etching, on the other hand, an etching solution capable of preventing damage to other members exposed if necessary, an etching method using the same, an etching solution kit, and a method for manufacturing a semiconductor substrate product The purpose is to provide.

The above problem has been solved by the following means.
[1] An etching solution for removing the metal layer disposed on the upper side of the silicide layer,
Containing a metal anticorrosive consisting of hydrochloric acid, nitric acid, a sulfonic acid compound and a compound containing a heteroatom and water;
The metal anticorrosive is an etching solution in which the following nickel solubility ratio of a chemical solution containing this and a chemical solution not containing this is 20% or more.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {1-Sb / Sa} × 100
Sa: Nickel solubility not including an anticorrosive agent Sb: Nickel solubility including an anticorrosive agent [2] The etching solution according to [1], wherein the metal anticorrosive agent is selected from a carboxylic acid compound, an azole compound, and a betaine compound.
[3] The etching solution according to [2], wherein the carboxylic acid compound is a polycarboxylic acid compound.
[4] The etching solution according to [2], wherein the azole compound is a thiazole compound.
[5] The etching solution according to [2], wherein the betaine compound is a compound having a quaternary ammonium group and a carboxyl group or a sulfonic acid group in the molecule.
[6] The etching solution according to any one of [1] to [5], wherein the sulfonic acid compound is methanesulfonic acid or toluenesulfonic acid.
[7] The etching solution according to any one of [1] to [6], wherein the silicide layer is NiPt silicide or NiPtGe silicide.
[8] The etching solution according to any one of [1] to [7], wherein the metal layer contains Ni, Pt, or a combination thereof.
[9] The etching solution according to any one of [1] to [8], which contains hydrochloric acid in an amount of 0.01% by mass to 0.5% by mass.
[10] The etching solution according to any one of [1] to [9], containing nitric acid in an amount of 0.1% by mass to 20% by mass.
[11] The etching solution according to any one of [1] to [10], which contains a sulfonic acid compound in an amount of 25% by mass to 95% by mass.
[12] The etching solution according to any one of [1] to [11], which contains a metal anticorrosive agent in an amount of 0.01% by mass to 5% by mass.
[13] An etching method for removing an unreacted metal layer disposed on the upper side of a silicide layer with an etchant, wherein the etchant comprises a metal anticorrosive comprising a compound containing hydrochloric acid, nitric acid, a sulfonic acid compound, and a heteroatom. Etching method that contains water and the metal anticorrosive has a following nickel solubility ratio of 20% or more between a chemical solution containing this and a chemical solution not containing this.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {Nickel solubility with anticorrosive agent / Nickel solubility without anticorrosive agent} × 100
[14] The etching method according to [13], wherein the metal anticorrosive is selected from a carboxylic acid compound, an azole compound, and a betaine compound.
[15] The etching method according to [13] or [14], wherein the silicide layer is NiPt silicide or NiPtGe silicide.
[16] The etching method according to any one of [13] to [15], which contains 0.05 to 10% by mass of a metal anticorrosive.
[17] An etching solution kit for removing the metal layer disposed on the upper side of the silicide layer,
A first liquid containing hydrochloric acid and water and a second liquid containing nitric acid and water;
At least one of the first liquid, the second liquid, and the third liquid other than that, which is adopted as necessary, contains a sulfonic acid compound and a metal anticorrosive composed of a compound containing a heteroatom, or both together, The metal anticorrosive is an etching solution kit in which the nickel solubility of a chemical solution containing the metal anticorrosive and the following nickel solubility ratio of the chemical solution not containing the metal anticorrosive is 20% or more.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {1-Sb / Sa} × 100
Sa: Nickel solubility not containing an anticorrosive agent Sb: Nickel solubility containing an anticorrosive agent [18] A step of forming a semiconductor substrate in which a silicon layer and a metal layer are formed in that order on the upper side of the silicon wafer, and a step of annealing the semiconductor substrate The semiconductor which has the process of providing the etching liquid of any one of Claims 1-12 to the said semiconductor substrate, making the said etching liquid and the said metal layer contact, and selectively removing the said metal layer A method for manufacturing a substrate product.

According to the present invention, even when germanium is included, damage to the silicide layer can be suppressed, and the metal layer disposed on the upper side thereof can be selectively and accurately removed. Further, while achieving a good etching described above, whereas it is possible to preferably prevent damage to the adjacent metal electrode layer such as aluminum or SiO ₂ or the like of the insulating layer.

It is sectional drawing which shows typically the manufacturing process example (before an etching) of the semiconductor substrate in one Embodiment of this invention. It is process drawing which shows the manufacture example of the MOS transistor in one Embodiment of this invention. It is an apparatus block diagram which shows a part of wet etching apparatus which concerns on preferable embodiment of this invention. It is a top view which shows typically the movement locus line of the nozzle with respect to the semiconductor substrate in one Embodiment of this invention.

  First, a preferred embodiment of an etching process according to the etching method of the present invention will be described with reference to FIGS.

[Etching process]
FIG. 1 shows the semiconductor substrate before and after etching. In the manufacturing example of the present embodiment, the metal layer 1 is disposed on the upper surface of the silicon layer 2. As the silicon layer, a SiGe epitaxial layer constituting a source electrode and a drain electrode is applied. In the present invention, the SiGe epitaxial layer is preferable because the remarkable effect of the etching solution is exhibited.

  Examples of the constituent material of the metal layer 1 include tungsten (W), titanium (Ti), cobalt (Co), nickel (Ni), NiPt, and the like. For the formation of the metal layer, a method usually applied to the formation of this kind of metal film can be used. Examples thereof include film formation by CVD (Chemical Vapor Deposition). The thickness of the metal layer at this time is not particularly limited, but examples include a film having a thickness of 5 nm to 50 nm. In the present invention, the metal layer is a NiPt layer (Pt content of more than 0% by mass and preferably 20% by mass or less) and a Ni layer (Pt content of 0% by mass), and the etching solution exhibits a remarkable effect. Therefore, it is preferable.

  After the metal layer 1 is formed above the silicon layer 2 in the above step (a), annealing (sintering) is performed, and a metal-Si reaction film (silicide layer) 3 is formed at the interface (step). (B)). Annealing may be performed under conditions normally applied to the production of this type of device, and for example, treatment at 200 to 1000 ° C. may be mentioned. The thickness of the silicide layer 3 at this time is not particularly limited, but examples include a layer of 50 nm or less, and an example of a layer of 10 nm or less. Although there is no lower limit, 1 nm or more is practical. This silicide layer is applied as a low-resistance film, and functions as a conductive portion that electrically connects a source electrode and a drain electrode located below the silicide layer and a wiring disposed thereon. Accordingly, when defects or corrosion occur in the silicide layer, this conduction is hindered, which may lead to quality degradation such as device malfunction. In particular, recently, the integrated circuit structure inside the substrate has been miniaturized, and even a minute damage can have a great influence on the performance of the element. Therefore, it is desirable to prevent such defects and corrosion as much as possible.

  Next, the remaining metal layer 1 is etched (step (b)-> step (c)). In the present embodiment, an etching solution is applied at this time, and the metal layer 1 is removed by applying and contacting the etching solution from the upper side of the metal layer 1. The form of application of the etchant will be described later.

  According to the etching solution according to a preferred embodiment of the present invention, in the etching step (step (c)), while the metal layer 1 is selectively etched, damage to the silicide layer underneath is effectively suppressed. Can be prevented. This effect is particularly remarkable for a germanium-containing NiPt silicide layer (referred to as a NiPtGeSi layer or a NiPtGe silicide layer) in which germanium is contained in a silicon layer located further below.

  The reason for the effect includes the points that have not been clarified yet, but is estimated as follows. As an example, regarding a NiPt silicide substrate, a composite metal structure composed of Ni, Pt, Si, and Ge exists in the silicide layer. At this time, in the dilute aqua chemical, Si in the silicide layer forms its oxide film (protective film), so the dissolution rate is slow, whereas Ni, which is a base metal, has a fast dissolution rate and silicon oxide on the surface. Elution progresses across the membrane layer. Therefore, it is understood that oxidation inside the silicide proceeds. Further, in the NiPt alloy, the pitting corrosion is accelerated by the preferential advancement of the more basic Ni elution. Here, in order to maintain the removability of the NiPt unreacted layer, it is desirable that the additive does not deteriorate the solubility of Pt.

  On the other hand, according to the etching solution of the present invention, since a specific additive (metal anticorrosive) is selected, the elution of Ni is suppressed while maintaining good etching properties of Pt / Ni on the upper side of the silicide layer. In addition, pitting corrosion on the surface of the silicide layer can be suppressed / prevented. In other words, it can be said that the contradictory performance is balanced and at a high level. The reaction mechanism described here includes a part including estimation, and the present invention is not construed as being limited in any way by this description. Although an example using NiPt metal has been described above, the silicide metal may be changed, and the etching solution according to the present invention can be widely applied to a case where the selectivity between a specific metal and the substrate is high. It is possible and effective.

  The silicon layer 2 is made of a SiGe epitaxial layer, and can be formed by crystal growth on a silicon substrate having specific crystallinity by a chemical vapor deposition (CVD) method. Alternatively, an epitaxial layer formed with desired crystallinity may be formed by an electron beam epitaxy (MBE) method or the like.

In order to make the silicon layer a P-type layer, it is preferable that boron (B) having a concentration of about 1 × 10 ¹⁴ cm ⁻³ to 1 × 10 ²¹ cm ⁻³ is doped. In order to form an N-type layer, phosphorus (P) is preferably doped at a concentration of 1 × 10 ¹⁴ cm ⁻³ to 1 × 10 ²¹ cm ⁻³ .

The Ge concentration in the SiGe epitaxial layer is preferably 3 to 15% by mass, and more preferably 5 to 10% by mass. In this specification, the concentration of Ge is a value measured as follows.
(Ge concentration)
The substrate of the first layer containing germanium (Ge) is analyzed in the depth direction from 0 to 30 nm by etching ESCA (Quanta, manufactured by ULVAC-PHI), and the average value of Ge concentration in the analysis result of 3 to 15 nm is calculated as the Ge concentration (mass %).

(Processing of MOS transistors)
FIG. 2 is a process diagram showing an example of manufacturing a MOS transistor. (A) is a MOS transistor structure formation process, (B) is a metal film sputtering process, (C) is a first annealing process, (D) is a metal film selective removal process, and (E) is a second annealing process. It is a process.
As shown in the figure, a gate electrode 23 is formed through a gate insulating film 22 formed on the surface of the silicon substrate 21. Extension regions may be separately formed on both sides of the gate electrode 23 of the silicon substrate 21. In the present embodiment, a protective layer 24 that prevents contact with the NiPt layer is formed on the upper side of the gate electrode 23. Further, a sidewall 25 made of a silicon oxide film or a silicon nitride film is formed, and a source region 26 and a drain region 27 are formed by ion implantation.
Next, as shown in the figure, a NiPt film 28 is formed and subjected to a rapid annealing process. As a result, the elements in the NiPt film 28 are diffused into the silicon substrate to be silicided. As a result, the upper portions of the source electrode 26 and the drain electrode 27 are silicided to form the NiPtGeSi source electrode portion 26A and the NiPtGeSi drain electrode portion 27A. At this time, if necessary, the electrode member can be changed to a desired state by performing the second annealing as shown in FIG. The first and second annealing temperatures are not particularly limited, and can be performed at 400 to 1100 ° C., for example.

  The NiPt film 28 remaining without contributing to silicidation can be removed by using the etching solution of the present invention (FIGS. 2C and 2D). At this time, what is shown in the figure is schematically shown, and there may or may not be a NiPt film deposited and left on top of the silicided layers (26A, 27A). The structure of the semiconductor substrate or its product is also shown in a very simplified manner, and may be interpreted as having necessary members if necessary.

  In some cases, another electrode formed of aluminum, copper, or the like is exposed inside the semiconductor substrate. Aluminum is a relatively inexpensive material and its application is spreading today. On the other hand, since it is a highly corrosive material, its protection is required. In particular, when exposed in the wet etching process as described above, the damage may become severe, and it is desired to prevent this as much as possible and maintain a good state. According to a preferred embodiment of the present invention, it is possible to effectively suppress or prevent such damage to an electrode made of aluminum or the like.

[Etching solution]
Next, a preferred embodiment of the etching solution of the present invention will be described. The etching liquid of this embodiment contains hydrochloric acid, nitric acid, a sulfonic acid compound, a metal anticorrosive, and water. Hereinafter, each component including an arbitrary one will be described.

(hydrochloric acid)
The etching solution according to the present invention contains hydrochloric acid. The concentration is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and particularly preferably 0.03% by mass or more in the etching solution. As an upper limit, 0.5 mass% or less is preferable, 0.1 mass% or less is more preferable, and 0.05 mass% or less is especially preferable. By setting it to the above upper limit or less, it is preferable in that excessive damage to the silicide layer is prevented. In particular, since hydrochloric acid (chlorine ions) contributes to the dissolution of nickel, it is preferable to limit this amount. On the other hand, it is preferable to set it more than the said lower limit from a viewpoint of etching a metal layer at sufficient speed | rate. The components of the etching solution need not be confirmed as hydrochloric acid. Chlorine ions (Cl ⁻ ) are identified in an aqueous solution, and the presence and amount thereof are grasped.
In the present invention, it is preferable to include only hydrochloric acid as the acid of the Group 7 element, and conversely, it is preferable not to include oxalic acid. It is understood that nitrosyl chloride (NOCl) is involved in the silicide layer containing germanium.

(nitric acid)
The etching solution according to the present invention contains nitric acid. The concentration is preferably 0.1% by mass or more in the etching solution, more preferably 1% by mass or more, and particularly preferably 2% by mass or more. As an upper limit, 20 mass% or less is preferable, 5 mass% or less is more preferable, and 3 mass% or less is especially preferable. By setting it to the above upper limit or less, it is preferable in that excessive damage to the silicide layer is prevented. On the other hand, it is preferable to set it more than the said lower limit from a viewpoint of etching a metal layer at sufficient speed | rate. The components of the etching solution need not be confirmed as nitric acid, but the presence and amount thereof can be grasped by identifying nitrate ions (NO ₃ ⁻ ) in the aqueous solution.

(Sulfonic acid compound)
The etching solution according to the present invention contains a sulfonic acid compound. This sulfonic acid compound is roughly classified into a sulfonic acid compound (A) and a sulfonic acid compound (B) because of its action.

・ Sulphonic acid compound (A)
The sulfonic acid compound (A) is a substance that has an effect of etching the metal layer, and examples thereof include methanesulfonic acid.
The concentration of the sulfonic acid compound (A) is preferably 25% by mass or more, more preferably 50% by mass or more, and particularly preferably 60% by mass or more in the etching solution. As an upper limit, 95 mass% or less is preferable, 80 mass% or less is more preferable, and 70 mass% or less is especially preferable.

・ Sulphonic acid compound (B)
The sulfonic acid compound (B) is a substance that has an action of suppressing oxidation of NiPt silicide, and is an optional additive. The sulfonic acid compound is not included in the metal corrosion inhibitor (essential component) described later. As the sulfonic acid compound (B), a compound represented by the following formula (1) is preferable.

When R is plural, each independently represents a linear or branched alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms), and cyclic alkyl group (carbon number). 3-12 are preferred, 3 to 6 and more preferably) a Cl, Br, F, OH, NO 2, or _SO 3 H, CO ₂ H. The alkyl group may further have a substituent, for example, Cl, Br, F, OH, NO ₂ , SO ₃ H, and CO ₂ H.
n is an integer of 0-5. m is an integer of 1-6.
Among these, R preferably has a substituent at least at the 4-position with respect to the SO ₃ H group, more preferably a paratoluenesulfonic acid compound, and particularly preferably paratoluenesulfonic acid.
The concentration of the sulfonic acid compound (B) is an optional component in the etching solution and may not be included. However, when applied, it is preferably more than 0% by mass, more preferably 0.5% by mass or more. It is preferable to contain 1% by mass or more. As an upper limit, 10 mass% or less is preferable, 5 mass% or less is more preferable, and 3 mass% or less is especially preferable.

(Metal anticorrosive)
The etchant according to the present invention contains a metal anticorrosive. The metal anticorrosive has a base metal anticorrosive property and is composed of a compound containing a hetero atom (preferably a nitrogen atom, an oxygen atom, or a sulfur atom). Specifically, it is a compound having a nickel powder solubility ratio (nickel solubility ratio) measured by the measurement method employed in the examples of 20% by mass or more. The nickel solubility ratio is further preferably 25% or more, more preferably 30% or more, further preferably 35% or more, and particularly preferably 40% or more. The upper limit is not particularly limited, but is practically 70% or less.

  The metal anticorrosive includes the sulfonic acid compound (B), a carboxylic acid compound (a compound having one or more carboxylic acids in the molecule), an azole compound (a heteroaromatic compound having one or more nitrogen atoms in the molecule). ) And a betaine compound (a compound having a basic group and an acidic group in the molecule).

-Carboxylic acid compound The carboxylic acid compound is preferably a polycarboxylic acid compound. Particularly preferred are dicarboxylic acid compounds, tricarboxylic acid compounds, and tetracarboxylic acid compounds. Specifically, malonic acid, oxalic acid, citric acid, tartaric acid, phthalic acid, and glutaric acid are preferable. Of these, malonic acid, oxalic acid, and citric acid are particularly preferable.

-Azole compound It is preferable that the said azole compound is a thiazole compound. The thiazole compound may further have a substituent. Examples of the substituent include an alkyl group (preferably having 1 to 12 carbons, more preferably 1 to 6 and particularly preferably 1 to 3), and an alkenyl group (carbon). Number 6-22 is preferable, 6-14 are more preferable, Alkynyl group (C6-C22 is preferable, 6-14 are more preferable), Alkoxy group (C1-C12 is preferable, 1-6 are more) Preferably, 1 to 3 are particularly preferred), an acyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an amino group (preferably 0 to 6 carbon atoms, preferably 0 to 3 carbon atoms). Are more preferred), Cl, Br, F, OH, NO ₂ , SO ₃ H, CO ₂ H.

Betaine compound The betaine compound is a compound having an acidic group and a basic group in the molecule, and preferably a compound having a quaternary ammonium group and a carboxyl group or a sulfonic acid group in the molecule. The carbon number of the betaine compound is not particularly limited, but is preferably 1 to 24, more preferably 1 to 16, and particularly preferably 1 to 8. Specifically, betaine [N (CH ₃ ) ₃ ⁺ —CH ₂ —COO ⁻ ] or sulfobetaine [N (CH ₃ ) ₃ ⁺ —CH ₂ —SO ₃ ⁻ ] is preferable.

  The concentration of the metal anticorrosive is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and 0.5% by mass in the etching solution. It is particularly preferable to contain at least%. As an upper limit, 10 mass% or less is preferable, 5 mass% or less is more preferable, and 2 mass% or less is especially preferable. By defining this addition amount, pitting corrosion of the silicide layer can be effectively suppressed while maintaining good etching properties, which is preferable.

(Aqueous medium)
Water (aqueous medium) is applied as the medium to the etching solution of the present invention. The water (aqueous medium) may be an aqueous medium containing a dissolved component as long as the effects of the present invention are not impaired, or may contain an unavoidable trace mixed component. Among these, water that has been subjected to purification treatment such as distilled water, ion-exchanged water, or ultrapure water is preferable, and ultrapure water that is used for semiconductor manufacturing is particularly preferable.

  The etching solution of the present invention preferably contains the above components, and more preferably consists essentially of each of the above components (consistently of). The phrase “consisting essentially of each of the above-mentioned components” means that it may contain a substance that does not substantially affect basic and novel properties. Moreover, when it has (have), contains (contain), etc., it is synonymous with (comprise), and it is the meaning which accept | permits inclusion of any other components.

(PH)
In the present invention, the pH of the etching solution is preferably 3 or less, more preferably 2 or less, and particularly preferably 1 or less. The upper limit value or less is preferable from the viewpoint of securing a sufficient etching rate of the NiPt film.

(kit)
The etching solution in the present invention may be a kit in which the raw material is divided into a plurality. For example, the liquid composition which contains the said hydrochloric acid in water as a 1st liquid is prepared, and the aspect which prepares the liquid composition which contains the said nitric acid in an aqueous medium as a 2nd liquid is mentioned. At this time, the sulfonic acid compound and the metal anticorrosive agent, which are other essential components, are contained in the first liquid, the second liquid, or other third liquid separately or together. Especially, it is preferable to make a 2nd liquid contain a sulfonic acid compound (B) and to make a 1st liquid contain a metal anticorrosive. The sulfonic acid compound (A) is preferably contained in both the first liquid and the second liquid.
As an example of its use, a mode in which both solutions are mixed to prepare an etching solution, and then applied to the etching process at an appropriate time is preferable. By doing in this way, it does not cause deterioration of the liquid performance by decomposition | disassembly of each component, and a desired etching effect | action can be exhibited effectively. Here, “timely” after mixing refers to the time period after mixing until the desired action is lost, specifically within 60 minutes, more preferably within 30 minutes, and more preferably within 10 minutes. Is more preferably within 1 minute, and particularly preferably within 1 minute. Although there is no lower limit in particular, it is practical that it is 1 second or more.

The method of mixing the first liquid and the second liquid is not particularly limited, but it is preferable that the first liquid and the second liquid are circulated through the respective flow paths, and both are merged at the merging point and mixed. After that, it is preferable that the flow path is further circulated, and the etching solution obtained by joining is discharged or jetted from the discharge port and brought into contact with the semiconductor substrate. In this embodiment, it is preferable that the process from the merging and mixing at the merging point to the contact with the semiconductor substrate is performed at the “timely”. This will be described with reference to FIG. 3. The prepared etching solution is sprayed from the discharge port 13 and applied to the upper surface of the semiconductor substrate S in the processing container (processing tank) 11. In the embodiment shown in the figure, the two liquids A and B are supplied, merge at the junction 14, and then move to the discharge port 13 via the flow path fc. A flow path fd indicates a return path for reusing the chemical solution. The semiconductor substrate S is on the turntable 12 and is preferably rotated together with the turntable by the rotation drive unit M. Note that an embodiment using such a substrate rotation type apparatus can be similarly applied to a process using an etching solution that is not used as a kit.
In addition, the etching liquid of this invention has few impurities, for example, a metal content, etc. in a liquid in view of the use use.

(container)
The etching solution of the present invention can be stored, transported and used in any container as long as corrosion resistance or the like does not matter (whether or not it is a kit). For semiconductor applications, a container having a high cleanliness and a low impurity elution is preferable. Examples of the containers that can be used include, but are not limited to, “Clean Bottle” series manufactured by Aicero Chemical Co., Ltd., “Pure Bottle” manufactured by Kodama Resin Co., Ltd., and the like.

[Etching conditions]
In the etching method of the present invention, it is preferable to use a single wafer type apparatus. Specifically, the single wafer type apparatus has a processing tank, and the semiconductor substrate is conveyed or rotated in the processing tank, the etching solution is applied to the processing tank, and the etching solution is brought into contact with the semiconductor substrate. It is preferable that the
Advantages of the single wafer type apparatus include (i) a fresh etching solution is always supplied, so that reproducibility is good, and (ii) in-plane uniformity is high. Furthermore, it is easy to use a kit in which the etching liquid is divided into a plurality of parts. For example, a method in which the first liquid and the second liquid are mixed in-line and discharged is suitably employed. At this time, it is preferable to adjust the temperature of both the first liquid and the second liquid, or adjust the temperature of only one of them and mix and discharge them in-line. Among these, an embodiment in which the temperature is controlled together is more preferable. The management temperature when adjusting the line temperature is preferably in the same range as the processing temperature described later.
The single wafer type apparatus is preferably provided with a nozzle in its processing tank, and a method of discharging the etching liquid onto the semiconductor substrate by swinging the nozzle in the surface direction of the semiconductor substrate is preferable. By doing so, the deterioration of the liquid can be prevented, which is preferable. Further, it is preferable that a kit is divided into two or more liquids so that harmful gases and the like are hardly generated.

  More detailed conditions will be described. In a preferred embodiment of the present invention, in a single wafer type apparatus, a semiconductor substrate is transported or rotated in a predetermined direction, and an etching solution is applied to the space (discharge, jetting, flowing down, dropping, etc.) And the etching solution is brought into contact with the semiconductor substrate.

  The processing temperature at which etching is performed is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and particularly preferably 55 ° C. or higher in the temperature measurement method shown in the examples described later. As an upper limit, it is preferable that it is 80 degrees C or less, and it is more preferable that it is 70 degrees C or less. By setting it to the above lower limit value or more, a sufficient etching rate for the silicide layer can be secured, which is preferable. By setting it to the upper limit value or less, it is preferable because the temporal stability of the etching processing rate can be maintained. The supply rate of the etching solution is not particularly limited, but is preferably 0.05 to 5 L / min, and more preferably 0.1 to 3 L / min. By setting it to the above lower limit value or more, it is preferable because uniformity in the etching plane can be ensured. By setting it to the upper limit value or less, it is preferable because stable performance 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 1000 rpm from the same viewpoint as described above.

  In the single-wafer etching according to a preferred embodiment of the present invention, it is preferable that the semiconductor substrate is transported or rotated in a predetermined direction, an etching solution is sprayed into the space, and the etching solution is brought into contact with the semiconductor substrate. . The supply rate of the etching solution and the rotation speed of the substrate are the same as those already described.

In the single wafer type apparatus configuration according to a preferred embodiment of the present invention, as shown in FIG. 4, it is preferable to apply the etching solution while moving the discharge port (nozzle). Specifically, in the present embodiment, when the etching solution is applied to the semiconductor substrate S having a silicide layer, the substrate is rotated in the r direction. On the other hand, the discharge port moves along a movement trajectory line t extending from the center to the end of the semiconductor substrate. As described above, in this embodiment, the direction of rotation of the substrate and the direction of movement of the discharge port are set to be different from each other. As a result, the etching solution can be applied evenly over the entire surface of the semiconductor substrate, and the etching uniformity is suitably ensured.
The moving speed of the discharge port (nozzle) is not particularly limited, but is preferably 0.1 cm / s or more, and more preferably 1 cm / s or more. On the other hand, the upper limit is preferably 30 cm / s or less, and more preferably 15 cm / s or less. The movement trajectory line may be a straight line or a curved line (for example, an arc shape). In either case, the moving speed can be calculated from the actual distance of the trajectory line and the time spent for the movement.

  The metal layer is preferably etched at a high etching rate. The etching rate [R1] of the metal layer is not particularly limited, but is preferably 20 Å / min or more, more preferably 50 Å / min or more, and particularly preferably 70 Å / min or more in consideration of production efficiency. Although there is no upper limit in particular, it is practical that it is 1200 kg / min or less.

  Although the exposed width of the metal layer is not particularly limited, it is preferably 2 nm or more, more preferably 4 nm or more, from the viewpoint that the advantages of the present invention become more prominent. Similarly, from the viewpoint of conspicuous effect, the upper limit is practically 1000 nm or less, preferably 100 nm or less, and more preferably 20 nm or less.

Furthermore, the etching solution of the present invention is preferably applied to a semiconductor substrate including a metal electrode layer such as Al, Cu, Ti, and W and an insulating film layer such as HfO ₂ , SiO ₂ , SiOC, and SiON. On the other hand, the etching solution according to a preferred embodiment of the present invention can exhibit an effective corrosion inhibiting effect. In addition, in this specification, when the composition of a metal compound is expressed by a combination of elements, it means that a composition having an arbitrary composition is widely included. For example, SiOC (SiON) means that Si, O, and C (N) coexist, and does not mean that the ratio of the amounts is 1: 1: 1. This is common in this specification, and the same applies to other metal compounds.

[Manufacture of semiconductor substrate products]
In the present embodiment, a step of forming a semiconductor substrate on which a silicon layer and a metal layer are formed on a silicon wafer, a step of annealing the semiconductor substrate, an etchant is applied to the semiconductor substrate, and the etchant and the metal It is preferable to manufacture a semiconductor substrate product having a desired structure through a step of contacting the layer and selectively removing the metal layer. At this time, the specific etching solution is used for etching. The order of the above steps is not construed as being limited, and further steps may be included between the steps.
The wafer size is not particularly limited, but a wafer having a diameter of 8 inches, a diameter of 12 inches, or a diameter of 14 inches can be suitably used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example.

The metal anticorrosive was subjected to the following tests, and the sheet resistance, nickel solubility, platinum solubility, and damage to the silicide layer were measured. The results are shown in Table 1. The results measured according to the formulation in Table A below are shown in Table 1 as “Standard Nickel Solubility”.
1. 0.1895 g of the following Ni powder was prepared.
2. First liquid plus 2 wt% each metal corrosion inhibitor sample and (HCI containing) and second solution and (HNO ₃ containing) prepared in formulation of table A.
3. The first liquid 100 g and the second liquid 100 g were heated to 60 ° C. and mixed.
4). Ni powder was added and treated at 60 ° C. for 10 minutes.
5. Unreacted Ni powder was removed by filtration.
6). The Ni dissolution concentration contained in the filtrate was measured with the following ICP apparatus.

Ｎｉ粉末：株式会社 高純度化学研究所ｎｉｃｋｅｌ、粉末、還元粉末
ＣＡＳ７７４０−０２−０ ：５３マイクロメートル以下
ＩＣＰ分析装置：製造元 Ｐｅｒｋｉｎ Ｅｌｍｅｒ
型番 Ｏｐｔｉｍａ ７３００ＰＶ

Ni powder: high purity chemical laboratory nickel, powder, reduced powder
CAS7740-02-0: 53 micrometers or less ICP analyzer: manufacturer Perkin Elmer
Model number Optima 7300PV

(Measuring method of sheet resistance)
The sheet resistance was measured using a four-terminal method, and a method based on JIS K7194.
Sheet resistance measuring instrument:
Manufacturer Hitachi Kokusai Electric Engineering Co., Ltd.
Model Number Body VR-120S
Four probe KS-TC-200-MT-200g
Measure the voltage when a current of 30 mA is applied

(Production of salicide processed substrate)
SiGe was epitaxially grown on a commercially available silicon substrate (diameter: 20 cm), and a Pt / Ni metal layer (thickness 20 nm, Pt / Ni ratio: 10/90 [mass basis]) was formed in that order. At this time, the SiGe epitaxial layer contained 5 to 10% by mass of germanium. This semiconductor substrate was annealed at 800 ° C. for 10 seconds, and a silicide layer was formed as a test substrate. The thickness of the silicide layer after annealing was 15 nm, and the thickness of the metal layer was 5 nm.

(Etching test)
The above-mentioned test substrate was etched under the following conditions with a single wafer apparatus (SPS-Europe BV, POLOS (trade name)), and an evaluation test was performed.
・ Processing temperature: 60 ℃
・ Discharge rate: 1 L / min.
・ Wafer rotation speed: 500rpm
・ Nozzle moving speed 7cm / s
The etching solution was supplied into two solutions by line mixing as described below (see FIG. 3). The temperature of the supply line fc was adjusted at 60 ° C. by heating.
First liquid (A): hydrochloric acid + methanesulfonic acid and water Second liquid (B): nitric acid + methanesulfonic acid and water The ratio of the first liquid to the second liquid was set to be equal in mass. The amount of methanesulfonic acid was blended in both liquids so that the first liquid and the second liquid were approximately equal in mass. The metal anticorrosive was added to the first liquid. Paratoluenesulfonic acid was added to the second liquid.

(Measurement method of processing temperature)
A radiation thermometer IT-550F (trade name) manufactured by HORIBA, Ltd. was fixed at a height of 30 cm above the wafer in the single wafer type apparatus. A thermometer was directed onto the wafer surface 2 cm outside from the wafer center, and the temperature was measured while flowing a chemical solution. The temperature was digitally output from the radiation thermometer and recorded continuously with a personal computer. Among these, the value obtained by averaging the temperature for 10 seconds at which the temperature was stabilized was defined as the temperature on the wafer.

(PH)
The pH was measured with F-51 (trade name) manufactured by HORIBA at room temperature (25 ° C.).

(Removability of metal layer)
The removal of the metal layer (Pt / Ni layer) was confirmed by the fact that Pt and Ni were not detected by ESCA measurement performed by silicide layer damage described later. As a result, the remarkable remainder of the metal layer was not confirmed in any of the samples of Examples and Comparative Examples.

(Silicon layer damage: D (Si))
The damage to the silicide layer was measured by the amount of change in the sheet resistance and the oxygen profile measurement by etching ESCA. The results were ranked as follows.
C where NiPt was removed C: Sheet resistance increased by 4.0 (Ω / □) or more B: No increase of 4.0 (Ω / □) or more was observed in sheet resistance, a depth of 2.5 nm by ESCA measurement The oxygen concentration was estimated to be 20% by mass or more. A: The sheet resistance was not increased by 3.5 (Ω / □) or more, and the oxygen concentration at a depth of 2.5 nm was 20% by ESCA measurement. Estimated less than

(Al layer damage: D (Al))
The Al layer was damaged by the amount of change in the sheet resistance. The results were ranked as follows.
C of the part to which Al is attached: Sheet resistance increases by 1.50 (mΩ / □) or more B: Sheet resistance increases by 1.0 (mΩ / □) or more and less than 1.5 (mΩ / □) A: Sheet The increase in resistance was less than 1.0 (mΩ / □)

ｃから始まる番号の試験は比較例
ＭＳＡ、ＨＣｌ、ＨＮＯ_３、ＰＴＳＡの数値は濃度（質量％）を意味する。金属防食剤の配合量（質量％）は（ ）内に示した。残部は水である。
ＮｉＰｔＧｅＳｉ Ｒｓ：薬液処理前後のシート抵抗の差分
（薬液処理前シート抵抗 − 処理後シート抵抗）
ＭＳＡ：メタンスルホン酸
ＰＴＳＡ：ｐ−トルエンスルホン酸
Ｄ（Ｓｉ）：シリサイド層のダメージ
Ｄ（Ａｌ）：Ａｌのダメージ

In the tests starting with c, the numerical values of Comparative Examples MSA, HCl, HNO ₃ and PTSA mean the concentration (mass%). The amount (% by mass) of the metal anticorrosive is shown in parentheses. The balance is water.
NiPtGeSi Rs: Difference in sheet resistance before and after chemical treatment
(Sheet resistance before chemical treatment-sheet resistance after treatment)
MSA: methanesulfonic acid PTSA: p-toluenesulfonic acid D (Si): silicide layer damage D (Al): Al damage

ICP (Ni): Nickel Solubility of Metal Anticorrosive The underline in the table indicates the “standard nickel solubility” of each anticorrosive (see Table A). Nickel Solubility Ratio =
(1-Sb ^* / Sa ^* ) × 100
Sa ^* : Standard nickel solubility of c01
Sb ^* : Standard nickel solubility of each anticorrosive

  From the above results, it can be seen that the etching solution of the present invention can achieve both good etching of the NiPt unreacted layer and suppression of oxidation of the NiPtGeSi layer (silicide layer). Moreover, the corrosion resistance of the terminal material which does not damage aluminum is also excellent.

1 Metal layer 2 Silicon layer 3 Silicide layer 11 Processing vessel (processing tank)
12 rotary table 13 discharge port 14 junction S substrate 21 silicon substrate 22 gate insulating film 23 gate electrode 24 protective film 25 sidewall 26 source electrode 27 drain electrode 28 NiPt film

Claims (18)

An etching solution for removing the metal layer disposed on the upper side of the silicide layer,
Containing a metal anticorrosive consisting of hydrochloric acid, nitric acid, a sulfonic acid compound and a compound containing a heteroatom and water;
The metal anticorrosive is an etching solution in which the following nickel solubility ratio of a chemical solution containing the metal anticorrosive and a chemical solution not containing the metal anticorrosive is 20% or more.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {1-Sb / Sa} × 100
Sa: Nickel solubility without anticorrosive agent Sb: Nickel solubility with anticorrosive agent   The etching solution according to claim 1, wherein the metal anticorrosive is selected from a carboxylic acid compound, an azole compound, and a betaine compound.   The etching solution according to claim 2, wherein the carboxylic acid compound is a polycarboxylic acid compound.   The etching solution according to claim 2, wherein the azole compound is a thiazole compound.   The etching solution according to claim 2, wherein the betaine compound is a compound having a quaternary ammonium group and a carboxyl group or a sulfonic acid group in the molecule.   The etching solution according to claim 1, wherein the sulfonic acid compound is methanesulfonic acid or toluenesulfonic acid.   The etching solution according to claim 1, wherein the silicide layer is NiPt silicide or NiPtGe silicide.   The etching solution according to claim 1, wherein the metal layer contains Ni, Pt, or a combination thereof.   The etching solution according to any one of claims 1 to 8, comprising hydrochloric acid in an amount of 0.01% by mass to 0.5% by mass.   The etching solution according to any one of claims 1 to 9, comprising nitric acid in an amount of 0.1% by mass to 20% by mass.   The etching liquid of any one of Claims 1-10 which contains a sulfonic acid compound in 25 mass% or more and 95 mass% or less.   The etching solution according to any one of claims 1 to 11, comprising a metal anticorrosive agent in an amount of 0.01 mass% to 5 mass%. An etching method for removing an unreacted metal layer disposed on an upper side of a silicide layer with an etchant, wherein the etchant comprises a metal anticorrosive comprising a compound containing hydrochloric acid, nitric acid, a sulfonic acid compound, and a heteroatom, and water. The metal anticorrosive is an etching method in which the following nickel solubility ratio of a chemical solution containing the metal anticorrosive and a chemical solution not containing the metal anticorrosive is 20% or more.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {Nickel solubility with anticorrosive agent / Nickel solubility without anticorrosive agent} × 100   The etching method according to claim 13, wherein the metal anticorrosive is selected from a carboxylic acid compound, an azole compound, and a betaine compound.   The etching method according to claim 13 or 14, wherein the silicide layer is NiPt silicide or NiPtGe silicide.   The etching method of any one of Claims 13-15 which contains a metal anticorrosive agent in 0.05 mass% or more and 10 mass% or less. An etching solution kit for removing a metal layer disposed on the upper side of a silicide layer,
A first liquid containing hydrochloric acid and water and a second liquid containing nitric acid and water;
At least one of the first liquid, the second liquid, and the third liquid other than that adopted as necessary contains a sulfonic acid compound and a metal anticorrosive composed of a compound containing a hetero atom, or both. The metal anticorrosive is an etching solution kit in which the nickel solubility of a chemical solution containing the metal anticorrosive and the following nickel solubility ratio of the chemical solution not containing the metal anticorrosive is 20% or more.
(Nickel solubility: Nickel powder is added to the etching solution and treated at 60 ° C. for 10 minutes. Dissolution concentration of nickel contained in the filtrate.)
Nickel solubility ratio (%)
= {1-Sb / Sa} × 100
Sa: Nickel solubility without anticorrosive agent Sb: Nickel solubility with anticorrosive agent   A step of forming a semiconductor substrate in which a silicon layer and a metal layer are formed in that order on the upper side of the silicon wafer, a step of annealing the semiconductor substrate, and the etching solution according to any one of claims 1 to 12 And a step of bringing the etching solution into contact with the metal layer and selectively removing the metal layer.

Images