JP2001144045A - Metal polishing fluid and board polishing method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal polishing fluid which can realize the polishing speed of tantalum, tantalum alloy or other tantalum compound used as a barrier conductor layer material faster than the polishing speed of a wiring metal film, and can form the flush pattern of the metal film with high reliability, and to provide a board polishing method using the fluid. SOLUTION: A metal polishing fluid contains conductor oxidizing agent, metal oxide dissolving agent, protective film forming agent and water, and has the ratio of the polishing speed of a barrier layer to the polishing speed of a metal layer not less than 1 and the ratio of the polishing speed of the barrier layer to the speed of an insulating layer not less than 10. The surface of a board including the copper layer, copper alloy layer and barrier layer is pressed against a polishing cloth on a surface plate and, in that state, the polishing surface plate and the board are moved relatively to each other while the metal polishing fluid is supplied to the polishing cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal polishing liquid used for polishing in a wiring forming step of a semiconductor device and a method for polishing a substrate using the polishing liquid.

[0002]

2. Description of the Related Art In recent years, a new fine processing technology has been developed in accordance with high integration and high performance of a semiconductor integrated circuit (LSI). Chemical mechanical polishing (CMP) is one of them.
This is a technique that is frequently used in flattening an interlayer insulating film, forming a metal plug, and forming an embedded wiring in an LSI manufacturing process, particularly in a multilayer wiring forming process. This technique is disclosed in, for example, US Pat. No. 4,944,836.

In recent years, in order to improve the performance of LSIs, attempts have been made to use copper and copper alloys as wiring materials. However, it is difficult to finely process copper and copper alloy by a dry etching method frequently used for forming a conventional aluminum alloy wiring. Therefore, a so-called damascene method of depositing and embedding a copper or copper alloy thin film on an insulating film in which a groove has been formed in advance and removing the copper or copper alloy thin film other than the groove by CMP to form an embedded wiring is mainly used. Has been adopted. This technology is disclosed in, for example,
No. 8822.

A general method of CMP of a metal such as copper and copper alloy is to attach a polishing pad on a circular polishing platen (platen), immerse the polishing pad surface with a metal polishing liquid, and form a metal film on a substrate. The surface on which is formed is pressed, and the polishing platen is turned in a state where a predetermined pressure (polishing pressure or polishing load) is applied from the back surface, and the metal of the convex portion is formed by mechanical friction between the polishing liquid and the convex portion of the metal film. This is to remove the film. The metal polishing solution used for CMP generally comprises an oxidizing agent and solid abrasive grains, and further includes a metal oxide dissolving agent and a protective film forming agent as necessary. It is considered that the basic mechanism is to oxidize the surface of the metal film with an oxidizing agent, and to scrape off the oxidized layer with solid abrasive grains. Since the oxide layer on the metal surface of the concave portion does not substantially touch the polishing pad (pad) and does not have the effect of shaving by the solid abrasive, the metal layer of the convex portion is removed with the progress of CMP, and the substrate surface is flattened. . See the Journal of Electrochemical S
138, Issue 11 (issued in 1991)
It is disclosed on pages 460-3644.

As a method of increasing the polishing rate by CMP, it is effective to add a metal oxide dissolving agent. It can be interpreted that dissolving (etching) the metal oxide particles removed by the solid abrasive grains in the polishing liquid increases the effect of the solid abrasive grains. The polishing rate by CMP is improved by the addition of the metal oxide dissolving agent. On the other hand, when the oxide layer on the surface of the metal film in the recess is also etched (dissolved) and the metal film surface is exposed, the metal film surface is further oxidized by the oxidizing agent. If this is repeated, the etching of the metal film in the concave portion proceeds. For this reason, a phenomenon (dishing) occurs in which the central portion of the surface of the metal wiring buried after polishing is dished like a dish, and the flattening effect is impaired.

To prevent this, a protective film forming agent is further added. The protective film forming agent forms a protective film on the oxide layer on the surface of the metal film and prevents the oxide layer from dissolving in the polishing liquid. This protective film can be easily scraped off by solid abrasive grains, and it is desired that the polishing rate by CMP is not reduced. In order to suppress corrosion during dishing and polishing of copper and copper alloys and to form a highly reliable LSI wiring, a metal oxide dissolving agent composed of aminoacetic acid or amide sulfuric acid such as glycine and a benzotriazole ( A method using a metal polishing liquid containing (BTA) has been proposed. This technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-8378.
No. 0 publication.

In the formation of a metal buried such as the formation of a damascene wiring of copper or a copper alloy or the formation of a plug wiring of tungsten or the like, if the polishing rate of a silicon dioxide film which is an interlayer insulating film formed other than the buried portion is high, Erosion occurs in which the thickness of the wiring together with the interlayer insulating film is reduced. As a result, variations in resistance occur due to an increase in wiring resistance, pattern density, and the like. Therefore, a characteristic in which the polishing rate of the silicon dioxide film is sufficiently low relative to the metal film to be polished is required. Therefore, a method has been proposed in which the polishing rate of the polishing liquid is made higher than pKa-0.5 by suppressing the polishing rate of silicon dioxide by anions generated by dissociation of the acid. This technique is disclosed, for example, in Japanese Patent Publication No. 2819.
196.

On the other hand, a tantalum, a tantalum alloy, a tantalum nitride, another tantalum compound, or the like is formed as a barrier layer in the lower layer of the wiring such as copper or copper alloy to prevent copper diffusion into the interlayer insulating film. . Therefore, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion where copper or copper alloy is embedded. However, since these barrier layer conductors have higher hardness than copper or copper alloy, a combination of polishing materials for copper and copper alloy often cannot provide a sufficient polishing rate. Therefore, a two-step polishing method including a first step of polishing copper or a copper alloy and a second step of polishing the barrier layer conductor has been studied.

In the second step, CMP of the barrier layer, it is necessary to prevent dishing of the copper and copper alloy buried wiring portion. In order to suppress the polishing rate and etching rate of copper or copper alloy, the pH of the polishing solution is adjusted. Was thought to be a negative effect.

[0010]

The tantalum, tantalum alloy, tantalum nitride and other tantalum compounds used as the barrier layer are chemically stable and difficult to etch, and have high hardness, so that the mechanical polishing can be performed using copper or copper. Not as easy as alloys. Therefore, when the hardness of the abrasive grains is increased,
Polishing scratches on copper or copper alloy cause electrical characteristics failure, and when the particle concentration of the abrasive grains is increased, the polishing rate of the silicon dioxide film increases and erosion occurs. there were. The present invention is directed to a metal which has a higher polishing rate for tantalum, tantalum alloy, tantalum nitride and other tantalum compounds used as a barrier layer conductor than a wiring metal film, and which can form a highly reliable buried pattern of a metal film. And a method for polishing a substrate using the same.

[0011]

The present inventors have found that polishing of tantalum, a tantalum alloy, tantalum nitride and other tantalum compounds used as a barrier layer conductor easily proceeds in a low pH region and a low oxidant concentration region. The polishing rate of the barrier layer is higher than that of the wiring metal film, and the polishing rate ratio (barrier layer / insulating film layer) between the barrier layer and the insulating film layer can be sufficiently increased. It has been found that a highly reliable buried pattern of a metal film can be formed. The present invention provides a polishing liquid containing (1) an oxidizing agent for a conductor, a metal oxide dissolving agent, a protective film forming agent, and water, wherein the polishing rate ratio (barrier layer / metal) of a metal to its barrier layer is 1 or more. Yes, barrier layer and insulating film layer (barrier layer /
This is a metal polishing liquid having a polishing rate ratio of the insulating film layer) of 10 or more. (2) 100 μm wide embedded metal wiring and width 1
A pattern in which an insulating film of 00 μm is alternately formed or a metal buried wiring having a width of 10 to 100 μm and a width of 10 to 100
In a pattern in which an insulating film of μm is formed alternately, the amount of dent (the amount of dishing) from the insulating film layer on both sides of the buried metal wiring portion when the barrier layer of the metal buried wiring metal film is polished until it is removed on the insulating film. ) Increase by 50 nm
The following metal polishing slurry according to the above (1), (3) a pattern in which a metal embedded wiring having a width of 100 μm and an insulating film having a width of 100 μm are alternately formed, or a width of 10 to 100 μm.
In the pattern in which the embedded metal wiring and the insulating film having a width of 10 to 100 μm are alternately formed, the time required from the start of polishing until the barrier layer of the embedded metal wiring metal film is removed on the insulating film (target polishing time). The amount of dent (dishing amount) from the insulating film layers on both sides of the metal buried wiring portion when polished for 1.5 times (50% over-polished) does not increase more than 20 nm from the dishing amount in the target polishing time. (4) A polishing liquid for metal according to (1), (4) a pattern in which a 4.5 μm wide embedded metal wiring and a 0.5 μm insulating film are alternately formed, or a 1-10 μm wide embedded metal wiring and a 0.1 μm wide embedded metal wiring. 1-1 μm
In a pattern having a wiring pattern density of 70% or more formed alternately with the insulating film, the peripheral insulation of the insulating film portion is polished until the barrier layer of the metal buried wiring metal film is removed on the insulating film around the pattern. The metal polishing slurry according to the above (1), wherein the amount of increase in the amount of dent (erosion) from the film layer is 80 nm or less, and (5) the metal embedded wiring having a width of 4.5 μm and the insulating film having a width of 0.5 μm. Alternatingly formed patterns or metal buried interconnects having a width of 1 to 10 μm and a width of 0.
In a pattern having a wiring pattern density of 70% or more in which an insulating film of 1 to 1 μm is alternately formed, the time required from the start of polishing until the barrier layer of the buried wiring metal film is removed on the insulating film around the pattern (target The amount of erosion (erosion amount) from the peripheral insulating film layer of the insulating film portion after polishing for 1.5 times the polishing time) (overpolishing by 50%) exceeds the erosion amount of the target polishing time by more than 40 nm. (6) The above-mentioned (1) to (1) wherein the pH of the metal polishing slurry is 3 or less and the concentration of the oxidizing agent is 0.01 to 3% by weight. 5) A metal polishing slurry according to any one of the above,
(7) The metal polishing slurry according to any one of (1) to (6), further comprising a water-soluble polymer, (8) the water-soluble polymer is polyacrylic acid or a salt thereof, polymethacrylic acid or The metal polishing slurry according to (7), which is at least one selected from the group consisting of salts thereof, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone; and (9) the metal oxide dissolving agent is an organic acid or an organic acid ester. A polishing slurry for metals according to any one of the above (1) to (8), which is at least one selected from ammonium salts of organic acids and sulfuric acid; (10) the organic acid is malonic acid, malic acid, tartaric acid, glycol The metal polishing slurry according to the above (9), which is at least one selected from an acid and a citric acid, and (11) the protective film forming agent is benzotriazole (B
TA) and the metal polishing slurry according to any one of the above (1) to (10), which is at least one member selected from the group consisting of hydrogen peroxide, nitric acid,
The polishing slurry for metals according to any one of the above (1) to (11), which is at least one selected from potassium periodate, hypochlorous acid and ozone water, and (13) the polishing slurry for metals, The metal polishing slurry according to any one of (1) to (12) above, wherein the abrasive grains are at least one selected from silica, alumina, ceria, titania, zirconia, and germania. The metal polishing slurry according to the above (13), (15) the metal polishing slurry according to the above (14), wherein the abrasive grains are colloidal silica or colloidal alumina having an average particle diameter of 100 nm or less, and (16) the conductor is:
The above (1) to (1), which are copper and copper alloy barrier layers,
5) The metal polishing slurry according to any one of 5), (17) the metal polishing slurry according to (16), wherein the barrier layer is at least one selected from tantalum, tantalum nitride, a tantalum alloy, and other tantalum compounds. It is a polishing liquid. Also, the present invention provides (18) a method for supplying a metal polishing liquid according to any one of the above (1) to (17) onto a polishing cloth of a polishing platen while supplying tantalum, tantalum nitride, a tantalum alloy and other metals. This is a polishing method for polishing a film to be polished by relatively moving a polishing platen and a substrate while a substrate having at least one barrier layer selected from a tantalum compound is pressed against a polishing cloth. (19) A surface containing copper and a copper alloy and its barrier layer is pressed against the polishing cloth while supplying the metal polishing liquid according to any one of the above (1) to (17) onto the polishing cloth of the polishing platen. This is a polishing method of polishing a film to be polished by relatively moving a polishing platen and a substrate in a state where the polishing is performed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The metal polishing liquid of the present invention is a polishing liquid containing a conductor oxidizing agent, a metal oxide dissolving agent, a protective film forming agent and water. A polishing liquid for metal is used in which the ratio of the barrier layer / metal film) is 1 or more and the polishing rate ratio between the barrier layer and the insulating film layer (barrier layer / insulating film layer) is 10 or more. The polishing rate ratio between the metal and the barrier layer (barrier layer / metal) is more preferably 2 or more, and the polishing rate ratio between the barrier layer and the insulating film layer (barrier layer / insulating film layer) is 30 or more. More preferred. The metal polishing slurry of the present invention comprises a pattern for alternately forming a 100 μm wide embedded metal wiring and a 100 μm width insulating film or a 10-100 μm wide embedded metal wiring and
In a pattern in which an insulating film having a thickness of 00 μm is alternately formed, the amount of dishing (amount of dishing) of the wiring portion metal from the insulating film layers on both sides when the barrier layer of the metal film with embedded metal is polished until removed on the insulating film. Is preferably 50 nm or less, more preferably 20 nm or less. The polishing slurry for metal of the present invention is a pattern in which a metal embedded wiring having a width of 100 μm and an insulating film having a width of 100 μm are alternately formed, or a metal embedded wiring having a width of 10 to 100 μm and an insulating film having a width of 10 to 100 μm are alternately formed. In the pattern to be polished, polishing was performed for 1.5 times as long as the required time (target polishing time) from the start of polishing until the barrier layer of the metal-buried wiring metal film was removed on the insulating film (5).
The amount of dent (dishing amount) from the insulating film layer on both sides of the metal wiring portion at the time of 0% over polishing is preferably not increased by more than 20 nm from the dishing amount of the target polishing time, more preferably not more than 10 nm. preferable. The metal polishing slurry of the present invention comprises a pattern in which a 4.5 μm-wide embedded metal wiring and a 0.5 μm-wide insulating film are alternately formed, or a metal embedded wiring having a width of 1 to 10 μm and an insulating film having a width of 0.1 to 1 μm. In a pattern having a wiring pattern density of 70% or more in which a film is alternately formed, from the peripheral insulating film layer of the insulating film portion when the barrier layer of the buried wiring metal film is polished until it is removed on the insulating film in the peripheral portion of the pattern The amount of increase in the dent amount (erosion amount) is preferably 80 nm or less, more preferably 40 nm or less.

The metal polishing slurry of the present invention comprises a pattern for alternately forming a 4.5 μm-width embedded metal wiring and a 0.5 μm-width insulating film or a metal embedded wiring having a width of 1 to 10 μm and a width of 0.1 to 10 μm. In a pattern having a wiring pattern density of 70% or more in which a 1 μm insulating film is alternately formed, the time required from the start of polishing to the removal of the barrier layer of the metal-buried wiring metal film on the insulating film around the pattern (target polishing) The amount of erosion (erosion amount) from the peripheral insulating film layer of the insulating film portion when polished (50% over-polished) for 1.5 times the time does not increase more than 40 nm from the erosion amount during the target polishing time. And more preferably not more than 20 nm. The polishing liquid for metal has a pH of 3 or less, and the concentration of the oxidizing agent is 0.
It is preferably from 01 to 3% by weight, and more preferably the concentration of the oxidizing agent is from 0.01 to 1.5% by weight. The metal polishing slurry of the present invention may further contain a water-soluble polymer. The water-soluble polymer is preferably at least one selected from the group consisting of polyacrylic acid or a salt thereof, polyacrylamide, polymethacrylic acid or a salt thereof, polyamic acid and a salt thereof, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. The metal oxide dissolving agent used in the present invention is preferably at least one selected from organic acids, organic acid esters, ammonium salts of organic acids, and sulfuric acid. The organic acid is more preferably at least one selected from malonic acid, malic acid, tartaric acid, glycolic acid and citric acid. The oxidizing agent for the conductor is preferably at least one selected from hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozone water. As the protective film forming agent, it is preferable to use at least one kind (BTAs) selected from benzotriazole (BTA) and its derivatives which have been widely used in the past. The metal-polishing liquid of the present invention may contain abrasive grains. The abrasive grains are preferably at least one selected from silica, alumina, ceria, titania, zirconia, and germania, and more preferably colloidal silica or colloidal alumina having an average particle diameter of 100 nm or less. The conductor is a barrier layer made of copper and a copper alloy, and the barrier layer is preferably made of tantalum, tantalum nitride, a tantalum alloy, or another tantalum compound. The polishing method of the present invention is a polishing method for polishing a barrier layer made of tantalum, tantalum nitride, a tantalum alloy, and other tantalum compounds using the above-mentioned metal polishing slurry. The polishing method of the present invention is a polishing method for polishing a surface including copper and a copper alloy and a barrier layer thereof using the above-mentioned metal polishing liquid. In the present invention, dishing, erosion and polishing scratches of copper and copper alloy wiring are suppressed by reducing the polishing solution to a low pH region and a low oxidizing agent concentration region, and the polishing rate of the barrier layer is reduced at a low abrasive concentration. Provided is a metal polishing liquid that realizes characteristics that are larger than a metal film and have a large polishing rate ratio (barrier layer / insulating film layer) between a barrier layer and an insulating film layer, and a method for polishing a substrate using the same. As a method of polishing the barrier layer, when the hardness or particle size of the abrasive grains is increased, polishing scratches occur in the copper alloy, which causes electrical characteristics failure, or when the particle concentration of the abrasive grains is increased. However, there is a problem that the polishing rate of the silicon dioxide film is increased and erosion occurs. The present inventors have found that polishing of tantalum, a tantalum alloy, and tantalum nitride and other tantalum compounds used as a barrier layer easily proceeds in a low pH region and a low oxidant concentration region. With a small and low abrasive concentration polishing liquid,
It has been found that high-speed polishing of the barrier layer can be realized. In addition, when such a polishing liquid is used, the polishing rate of the insulating film layer is sufficiently lower than that of the barrier layer, so that the insulating film layer serves as a polishing stopper, so that not only the polishing time can be easily controlled, but also the polishing time can be easily controlled. Erosion is not a problem. Further, it was found that since the oxidant concentration was sufficiently low, the dishing of the wiring due to an increase in the etching rate of copper and copper alloy, which generally becomes a problem in a low pH range, was not a problem.

In the present invention, a barrier layer and a metal film containing copper or a copper alloy are formed and filled on a substrate having a concave portion of silicon dioxide on the surface. When the substrate is first subjected to CMP using a polishing liquid for copper and copper alloy having a sufficiently high polishing rate ratio of copper or copper alloy / barrier layer, the barrier layer at the convex portion of the substrate is exposed on the surface, and the copper or copper A desired conductor pattern with the alloy film left is obtained. The metal polishing liquid of the present invention is a polishing liquid containing a conductor oxidizing agent, a metal oxide dissolving agent, a protective film forming agent, and water. If the polishing rate ratio between the metal and its barrier layer (barrier layer / metal) is less than 1, dishing increases due to the polishing of the barrier layer in the second step, and the barrier layer and the insulating film layer (barrier layer / insulating film layer) If the polishing rate ratio is less than 10, the insulating film layer does not function as a polishing stopper, and erosion occurs.

The metal polishing slurry of the present invention comprises a pattern for alternately forming a 100 μm wide embedded metal wiring and a 100 μm wide insulating film, or a 10-100 μm wide embedded metal wiring and a 10-100 μm wide insulating film. In the pattern formed alternately, the amount of dent (dishing amount) from the both-side insulating film layer of the wiring portion metal when polishing is performed until the barrier layer of the buried wiring metal film is removed on the insulating film is 50 nm or less. is there. If the increase is larger than 50 nm, an increase in the electrical resistance of the wiring becomes a problem.

The metal polishing slurry of the present invention comprises a pattern for alternately forming a 100 μm-wide embedded metal wiring and a 100 μm-wide insulating film, or a 10-100 μm-wide embedded metal wiring and a 10-100 μm-wide insulating film. In the pattern formed alternately, polishing was performed for 1.5 times the time required from the start of polishing until the barrier layer of the buried wiring metal film was removed on the insulating film (target polishing time) (50%).
The dent amount (dishing amount) of the wiring portion metal from the insulating film layers on both sides at the time of overpolishing does not increase more than 20 nm from the dishing amount in the target polishing time. If the increase exceeds 20 nm, an increase in the electrical resistance of the wiring becomes a problem.

The metal polishing slurry of the present invention comprises a pattern for alternately forming a 4.5 μm-wide embedded metal wiring and a 0.5 μm-wide insulating film, or a metal embedded wiring having a width of 1 to 10 μm and a width of 0.1 to 10 μm. In a pattern having a wiring pattern density of 70% or more in which a 1 μm insulating film is alternately formed, the peripheral insulating of the insulating film portion is polished until the barrier layer of the buried wiring metal film is removed on the insulating film in the peripheral portion of the pattern. The amount of increase in the amount of dent (erosion) from the film layer is 80 nm or less. If the increase exceeds 80 nm, an increase in the electrical resistance of the wiring becomes a problem.

The metal polishing slurry of the present invention comprises a pattern in which a 4.5 μm-width embedded metal wiring and a 0.5 μm-wide insulating film are alternately formed, or a metal embedded wiring having a width of 1 to 10 μm and a width of 0.1 to 10 μm. In a pattern having a wiring pattern density of 70% or more in which a 1 μm insulating film is alternately formed, the time required from the start of polishing until the barrier layer of the buried wiring metal film is removed on the insulating film around the pattern (target polishing time) ), The amount of dent (erosion amount) from the peripheral insulating film layer of the insulating film portion when the polishing is performed for 1.5 times (50% over polishing) does not increase more than 40 nm from the erosion amount during the target polishing time. Increase by 40
If it exceeds nm, an increase in electric resistance of the wiring becomes a problem.

The pH of the metal polishing slurry in the present invention is 3
If it is larger than, the polishing rate of tantalum, tantalum alloy, tantalum nitride and other tantalum compounds is small regardless of the concentration of the oxidizing agent. The pH can be adjusted by the amount of acid added. It can also be adjusted by adding an alkali component such as ammonia, sodium hydroxide, or tetramethylammonium hydride. The oxidizing agent concentration of the metal polishing liquid in the present invention is preferably 0.01 to 3% by weight, more preferably 0.01 to 1.5% by weight. The polishing rate of tantalum, a tantalum alloy, tantalum nitride, and other tantalum compounds serving as barrier layers reaches a maximum near 0.15% by weight. This is because a primary oxide layer that is easily mechanically polished is formed on the surface of a conductive film such as tantalum, a tantalum alloy, tantalum nitride, or another tantalum compound by an oxidizing agent, and a high polishing rate can be obtained. On the other hand, the polishing rate of copper and copper alloy increases as the concentration of the oxidizing agent increases. When the concentration of the oxidizing agent is in the range of 0.01 to 3% by weight, the polishing rate ratio of the barrier layer conductor to copper and copper alloy can be adjusted. If the concentration of the oxidizing agent is higher than 3% by weight, the etching rate of copper and copper alloy is increased and dishing is liable to occur, and the surface of the conductor film such as tantalum, tantalum alloy, tantalum nitride, and other tantalum compounds. In addition, since a secondary oxide layer that is less polished than the primary oxide layer is formed, the polishing rate decreases. If the concentration of the oxidizing agent is less than 0.01% by weight, the polishing rate of tantalum, tantalum alloy, tantalum nitride and other tantalum compounds is low because the oxide layer is not sufficiently formed, and the polishing rate of copper and copper alloy is low. Not a target.

The metal polishing slurry of the present invention may contain a water-soluble polymer. Since the water-soluble polymer is adsorbed on tantalum, a tantalum alloy, tantalum nitride or other tantalum compounds, or the oxide film surface thereof, the oxidizing agent concentration range in which a high polishing rate of these barrier layer conductor films can be obtained is reduced. . Further, since the water-soluble polymer is easily adsorbed on the surface of a nitride compound film such as a tantalum nitride film or titanium nitride, the polishing rate of the nitride compound film such as a tantalum nitride film or titanium nitride decreases. However, water-soluble polymers
It has the effect of forming a metal surface protective film and improves flattening characteristics such as dishing and erosion.

As the water-soluble polymer in the present invention, those selected from the following group were found to be suitable.
Polyacrylic acid, ammonium polyacrylate, polyacrylic acid sodium salt, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, a polymer having a monomer having a carboxyl group such as polyacrylamide as a basic structural unit, and a polymer thereof. Polymers having a basic structural unit of a monomer having a vinyl group such as a salt, polyvinyl alcohol, and polyvinylpyrrolidone are exemplified. However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, an acid or an ammonium salt thereof is preferable because contamination by an alkali metal, an alkaline earth metal, a halide or the like is not desirable. This is not the case when the substrate is a glass substrate or the like. By adding these water-soluble polymers, dishing characteristics can be improved by the effect of suppressing the etching by the protective film forming agent.

Examples of the oxidizing agent for the conductor in the present invention include hydrogen peroxide (H ₂ O ₂ ), nitric acid, potassium periodate, hypochlorous acid, ozone water and the like. Of these, hydrogen peroxide is particularly preferred. . When the substrate is a silicon substrate including an element for an integrated circuit, contamination by an alkali metal, an alkaline earth metal, a halide, or the like is not desirable, and an oxidizing agent containing no nonvolatile component is desirable. However, hydrogen peroxide is most suitable because the composition of ozone water changes drastically with time. However, when the substrate to be applied is a glass substrate or the like that does not contain a semiconductor element, an oxidizing agent containing a nonvolatile component may be used.

The metal oxide dissolving agent used in the present invention is preferably at least one selected from organic acids, organic acid esters, ammonium salts of organic acids, and sulfuric acid. As organic acids, formic acid, acetic acid, propionic acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3 dimethylbutyric acid, 2-
Ethyl butyric acid, 4-methylpentanoic acid, n-heptanoic acid,
2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid acid,
Malic acid, tartaric acid, citric acid and the like, and esters of these organic acids, salts such as ammonium salts of organic acids,
Other metal oxide dissolving agents include sulfuric acid, nitric acid, ammonia, ammonium salts such as ammonium persulfate,
Examples include ammonium nitrate, ammonium chloride, chromic acid, and the like, and mixtures thereof. Among these, malonic acid, malic acid, tartaric acid, glycolic acid and citric acid are preferred in that a practical CMP polishing rate can be obtained.

The protective film forming agent in the present invention is preferably selected from the following group. Ammonia; alkylamines such as dimethylamine, trimethylamine, triethylamine and propylenediamine; and amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan; glycine, L-alanine, β-alanine, L-2-aminobutyric acid , L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diiodo-L-tyrosine, β- (3,
4-dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L-cystinic acid , L-aspartic acid, L-glutamic acid, S-
(Carboxymethyl) -L-cystine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine,
L-arginine, L-canavanine, L-citrulline, δ
-Hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, 3
Amino acids such as -methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipain; dithizone, cuproin (2,2'-biquinoline), neocuproin (2,9-dimethyl) -1,
10-phenanthroline), bathocuproine (2,9-
Imines such as dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazone (biscyclohexanone oxalylhydrazone); benzimidazole-
2-thiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl) thiobutyric acid, 2-mercaptobenzothiazole, 1,2,3
-Triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole , 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole, 4-methoxycarbonyl-1H-benzotriazole, 4-butoxycarbonyl-1H-benzotriazole, 4-octyloxycarbonyl-1H-benzotriazole, 5-hexyl Benzotriazole, N
-(1,2,3-benzotriazolyl-1-methyl)-
N- (1,2,4-triazolyl-1-methyl) -2-
Azoles such as ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid; mercaptans such as nonylmercaptan, dodecylmercaptan, triazinethiol, triazinedithiol, triazinetrithiol; and glucose, cellulose And the like. Among them, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, triazinedithiol, benzotriazole, 4-hydroxybenzotriazole, 4-carboxylbenzotriazole butyl ester, tolyltriazole, and naphthotriazole have both a high CMP rate and a low etching rate. Preferred above. In particular, benzotriazole (BTA), BT
A derivatives, for example, those obtained by substituting one hydrogen atom of the benzene ring of BTA with a methyl group, those obtained by substituting with a tolyltriazole or carboxyl group, benzotriazole-4-carboxylic acid (methyl, ethyl, propyl,
Butyl and octyl esters) or naphthotriazo-
And naphthotriazole derivatives and mixtures containing them.

The metal polishing slurry of the present invention may contain solid abrasive grains. As abrasive grains, silica, alumina, zirconia, ceria, titania, inorganic abrasive grains such as silicon carbide,
Any one of organic abrasives such as polystyrene, polyacryl, and polyvinyl chloride may be used, but the dispersion stability in the polishing solution is good, the number of polishing scratches (scratch) generated by CMP is small, and the average particle size is 100 nm. The following colloidal silica and colloidal alumina are preferred. The average particle size is
It is more preferably 50 nm or less at which the polishing rate of the barrier layer becomes higher and the polishing rate of silicon dioxide becomes lower. A method of producing colloidal silica by hydrolysis of silicon alkoxide or ion exchange of sodium silicate is known, and a method of producing colloidal alumina by hydrolysis of aluminum nitrate is known.

The conductor film to which the present invention is applied is a barrier layer of copper and a copper alloy, and is made of tantalum, a tantalum alloy, tantalum nitride, or another tantalum compound.

The amount of the metal oxide dissolving agent used in the present invention is 0.000 to the total amount of 100 g of the conductor oxidizing agent, metal oxide dissolving agent, protective film forming agent, water-soluble polymer and water.
1 to 0.05 mol, preferably 0.001
More preferably, it is set to 0.01 mol. If the amount exceeds 0.05 mol, the etching of the copper alloy tends to increase.

The compounding amount of the protective film forming agent in the present invention is as follows:
The oxidizing agent for the conductor, the metal oxide dissolving agent, the protective film forming agent, the water-soluble polymer, and the total amount of water to 100 g are 0.0001 to
0.01 mol is preferable, and 0.0005 to
More preferably, it is 0.005 mol. If the amount is less than 0.0001 mol, the etching of the copper alloy tends to increase, and if it exceeds 0.01 mol, the effect remains unchanged.

In the present invention, a water-soluble polymer can be added. The compounding amount of the water-soluble polymer is 0.001 to 0.5% by weight based on 100 g of the total amount of the conductor oxidizing agent, metal oxide dissolving agent, protective film forming agent, water-soluble polymer and water. More preferably, it is 0.01 to 0.2% by weight. If the amount is less than 0.001% by weight,
There is a tendency that the effect of the combined use with the protective film forming agent does not appear in the suppression of the etching, and when it exceeds 0.5% by weight, the polishing rate by the CMP tends to decrease.

In the present invention, abrasive grains can be contained.
The amount of abrasive added is from 0.01% by weight to 10% by
%, More preferably in the range of 0.05% to 5% by weight. If the amount is less than 0.01%, the effect of containing abrasive grains is not obtained, and if the amount is more than 10% by weight, the polishing rate by CMP saturates.

[0031]

The present invention will be described below in detail with reference to examples. The present invention is not limited by these examples.

(Examples 1 and 2 and Comparative Examples 1 and 2) (Preparation of Polishing Solution for Metal) 0.4 parts by weight of DL-malic acid as a metal oxide dissolving agent, 0.05 parts by weight of water-soluble polymer, protection 97.85 parts by weight of water to 0.2 parts by weight of BTA as a film-forming agent (97.9 parts by weight when no water-soluble polymer is added)
Was added and dissolved, and 1 part by weight of colloidal silica was added as abrasive grains. In addition, when polishing, hydrogen peroxide (special grade reagent,
A 30% aqueous solution (0.5% by weight) was used as a metal polishing liquid. Abrasive grains have an average particle diameter of 20 n produced by hydrolysis of tetraethoxysilane in an aqueous ammonia solution.
m of colloidal silica. In Comparative Example 1, 1 part by weight of colloidal silica having a particle diameter of 100 nm was added as abrasive grains, and 97.9 parts by weight of water and 0.5 part by weight of hydrogen peroxide were used, and the organic acid and the protective film forming agent were the same. A metal-free polishing liquid having a composition not containing a water-soluble polymer was used. In Comparative Example 2, 1 part by weight of colloidal silica having a particle size of 20 nm was added as abrasive grains, water was set to 88.4 parts by weight, and hydrogen peroxide was set to 10.0 parts by weight, and the organic acid and the protective film forming agent were the same. A metal-free polishing liquid having a composition not containing a water-soluble polymer was used. In Examples 1 and 2 and Comparative Examples 1 and 2, CMP was performed using the water-soluble polymer shown in Table 1 with the above metal polishing slurry.
did.

(Polishing conditions) Substrate: Silicon substrate on which a 200 nm-thick tantalum film was formed. Silicon substrate on which a 1-μm-thick silicon dioxide film was formed. Silicon substrate on which a 1-μm-thick copper film was formed. Wiring groove depth 0.5 μm. / Barrier layer: Tantalum film thickness 50n
Polishing pad: (IC1000 (manufactured by Rodell)) Foamed polyurethane resin having closed cells Polishing pressure: 2
4.5 KPa (250 gf / cm ² ) Relative speed between substrate and polishing platen: 18 m / min (Evaluation of polished product) Polishing speed by CMP: Difference in film thickness between before and after CMP of each film is converted from electric resistance value. I asked. Etching rate: Stirred polishing liquid (25 ° C., 100 rpm)
The difference in copper film thickness before and after immersion in m) was calculated from the electrical resistance value. Dishing amount: A groove having a depth of 0.5 μm is formed in silicon dioxide, a tantalum nitride film having a thickness of 50 nm is formed as a barrier layer by a known sputtering method, and a copper film is similarly formed by a sputtering method at a thickness of 1.0 μm. Then, two-stage polishing is performed using a silicon substrate embedded by a known heat treatment as a base, and a wiring metal part width of 100 μm is measured with a stylus type step meter.
From the surface shape of the stripe pattern portion in which the insulating film portion width was alternately arranged at 100 μm, the amount of film reduction of the wiring metal portion with respect to the insulating film portion was determined. As the first-stage polishing liquid for copper, the polishing rate ratio of copper to tantalum is sufficiently large (Cu / Ta).
> 1000) Polishing was performed using a polishing solution for copper and copper alloy, and a base sample was prepared so that the dishing amount measured with the barrier layer exposed on the insulating film portion was 50 nm. As the second-stage polishing, the polishing was performed for a time when the barrier layer just disappears in the insulating film portion (over polishing: 0%) and 1.5 times the time (over polishing: 50%). Erosion amount: The surface shape of a stripe pattern portion having a total width of 2.5 mm formed by alternately arranging a wiring metal portion width of 45 μm and an insulating film portion width of 5 μm formed on the dishing amount evaluation substrate is measured by a stylus type profilometer. Then, the amount of film reduction of the insulating film portion near the center of the pattern with respect to the insulating film field portion around the stripe pattern was determined. As the first polishing liquid for copper, polishing is performed using a polishing liquid for copper and a copper alloy having a sufficiently high polishing rate ratio of copper to tantalum (Cu / Ta> 1000), and a barrier layer is formed on the insulating film portion. A substrate sample was prepared so that the erosion amount measured in a state where was exposed was 20 nm. As the second-stage polishing, the polishing was performed for a time when the barrier layer just disappears in the insulating film portion (over polishing: 0%) and 1.5 times the time (over polishing: 50%). Wiring resistance amount: A wiring resistance value of 1 mm in wiring length was measured in a 100 μm-wide copper wiring pattern of a dishing amount measuring unit. Further, in a 4.5 μm-wide copper wiring pattern of the erosion amount measuring section, a wiring resistance value of a wiring length of 1 mm was measured.

Polishing rates by CMP in Examples 1 and 2 and Comparative Examples 1 and 2, polishing rate ratios, dishing amounts and erosion amounts, and increases thereof (1 in case of 0% over polishing)
Table 1 shows the amount of increase after the step polishing, and the amount of increase from 0% overpolishing in the case of 50% overpolishing. Also,
Table 2 shows the electrical resistance of the wiring.

[0035]

[Table 1] : Over polishing 0% is the increase from the first polishing, over polishing
50% is increase from 0% over polishing

[0036]

[Table 2]

In Comparative Example 1, since the polishing rate of the silicon dioxide film was high and the polishing rate ratio (Ta / SiO ₂ ) between the tantalum and the silicon dioxide film was smaller than 10, the increase in the wiring resistance due to the erosion was large. In Comparative Example 2, since the polishing rate of copper was high and the polishing rate of Ta was low, the polishing rate ratio of tantalum to copper (Ta / Cu)
Is smaller than 1, and the polishing rate ratio (Ta / SiO ₂ ) between the tantalum and the silicon dioxide film is smaller than 10. As a result, erosion, particularly dishing, is large, and the increase in wiring resistance is large. In contrast, in Examples 1 and 2,
The polishing rate ratio (Ta / Cu) of tantalum to copper is 2 or more, and the polishing rate ratio (T
a / SiO ₂ ) is more than 30, good dishing and erosion properties are obtained. In particular, in the case of Example 2 containing a water-soluble polymer, the overpolishing resistance is good.

[0038]

According to the present invention, it has been found that polishing of tantalum, a tantalum alloy, tantalum nitride and other tantalum compounds used as a barrier layer conductor easily proceeds in a low pH region and a low oxidant concentration region. Thereby, the polishing rate of the barrier layer is higher than that of the wiring metal film, and the polishing rate ratio (barrier layer / insulating film layer) between the barrier layer and the insulating film layer can be sufficiently increased. Embedded pattern of highly conductive metal film
An object of the present invention is to provide a metal polishing liquid capable of forming a metal.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Tsuyoshi Uchida 48 Wadai, Tsukuba, Ibaraki Prefecture Within Hitachi Chemical Co., Ltd. (72) Inventor Akiko Igarashi 48 Wadai, Tsukuba-shi, Ibaraki Pref. Hitachi Chemical Co., Ltd.

Claims (19)

[Claims] 1. A polishing liquid containing an oxidizing agent for a conductor, a metal oxide dissolving agent, a protective film forming agent and water, wherein the polishing rate ratio (barrier layer / metal) of a metal and its barrier layer is 1 or more,
A metal-polishing liquid wherein the polishing rate ratio between the barrier layer and the insulating film layer (barrier layer / insulating film layer) is 10 or more. 2. A metal embedded wiring having a width of 100 μm and a width of 1
A pattern in which an insulating film of 00 μm is alternately formed or a metal buried wiring having a width of 10 to 100 μm and a width of 10 to 100
In a pattern in which an insulating film of μm is formed alternately, the amount of dent (the amount of dishing) from the insulating film layer on both sides of the buried metal wiring portion when the barrier layer of the metal buried wiring metal film is polished until it is removed on the insulating film. ) Increase by 50 nm
The metal polishing slurry according to claim 1, wherein: 3. A metal embedded wiring having a width of 100 μm and a width of 1
A pattern in which an insulating film of 00 μm is alternately formed or a metal buried wiring having a width of 10 to 100 μm and a width of 10 to 100
In a pattern in which a μm insulating film is alternately formed, the time required from the start of polishing until the barrier layer of the metal film with embedded metal wiring is removed on the insulating film (target polishing time)
The dent amount (dishing amount) from the insulating film layers on both sides of the metal buried wiring portion when polished for 1.5 times the time (performed by 50% overpolishing) does not increase more than 20 nm from the dishing amount in the target polishing time. Claim 1
Polishing liquid for metals according to 4. 4. A pattern for alternately forming a 4.5 μm wide embedded metal wiring and a 0.5 μm width insulating film, or a 1-10 μm wide embedded metal wiring and a 0.1-1 μm width.
In a pattern having a wiring pattern density of 70% or more formed alternately with the insulating film, the peripheral insulation of the insulating film portion is polished until the barrier layer of the metal buried wiring metal film is removed on the insulating film around the pattern. 2. The metal polishing slurry according to claim 1, wherein the amount of increase in the amount of dent (erosion) from the film layer is 80 nm or less. 5. A pattern in which 4.5 μm wide embedded metal wiring and a 0.5 μm width insulating film are alternately formed, or 1-10 μm wide embedded metal wiring and 0.1-1 μm wide.
Time required from the start of polishing to the removal of the barrier layer of the buried wiring metal film on the insulating film in the periphery of the pattern (target polishing time) in a pattern having a wiring pattern density of 70% or more in which the insulating film is alternately formed. The amount of dent (erosion amount) from the peripheral insulating film layer of the insulating film portion when polished for 1.5 times the time (performed by 50% overpolishing)
Is 40 nm from the erosion amount of the target polishing time.
2. The metal polishing slurry according to claim 1, wherein the polishing fluid does not increase more than. 6. The metal polishing slurry according to claim 1, wherein the pH of the metal polishing slurry is 3 or less and the concentration of the oxidizing agent is 0.01 to 3% by weight. . 7. The method according to claim 1, further comprising a water-soluble polymer.
7. The metal polishing slurry according to claim 6. 8. The method according to claim 7, wherein the water-soluble polymer is at least one selected from the group consisting of polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. Polishing liquid for metals. 9. The metal polishing slurry according to claim 1, wherein the metal oxide dissolving agent is at least one selected from organic acids, organic acid esters, ammonium salts of organic acids, and sulfuric acid. . 10. The metal polishing slurry according to claim 9, wherein the organic acid is at least one selected from malonic acid, malic acid, tartaric acid, glycolic acid and citric acid. 11. The metal polishing slurry according to claim 1, wherein the protective film forming agent is at least one selected from benzotriazole (BTA) and derivatives thereof. 12. The oxidizing agent for the conductor is hydrogen peroxide, nitric acid,
The metal polishing slurry according to any one of claims 1 to 11, wherein the metal polishing slurry is at least one selected from potassium periodate, hypochlorous acid, and ozone water. 13. The metal polishing liquid according to claim 1, wherein abrasive grains are added to the metal polishing liquid. 14. The abrasive grains are silica, alumina, ceria,
The metal polishing slurry according to claim 13, wherein the metal polishing slurry is at least one selected from titania, zirconia, and germania. 15. The metal-polishing liquid according to claim 14, wherein the abrasive is colloidal silica or colloidal alumina having an average particle diameter of 100 nm or less. 16. The metal polishing slurry according to claim 1, wherein the conductor is a barrier layer of copper and a copper alloy. 17. The metal polishing slurry according to claim 16, wherein the barrier layer is at least one selected from tantalum, tantalum nitride, a tantalum alloy, and other tantalum compounds. 18. A tantalum, a tantalum nitride, a tantalum alloy and another tantalum compound, while supplying the metal polishing liquid according to any one of claims 1 to 17 onto a polishing cloth of a polishing platen. A polishing method for polishing a film to be polished by relatively moving a polishing platen and a substrate while a substrate having at least one barrier layer is pressed against a polishing cloth. 19. A surface containing copper and a copper alloy and its barrier layer is supplied to the polishing cloth while supplying the metal polishing liquid according to claim 1 onto the polishing cloth of the polishing platen. A polishing method for polishing a film to be polished by relatively moving a polishing platen and a substrate in a pressed state.