JP2009027133A - Semiconductor process and wet processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor process and a wet processing apparatus capable of preventing erosion generated in a contact between different materials in a wet process, and of removing microparticles on a wafer. <P>SOLUTION: A lower electrode 1 carrying out electrostatic adsorption of a wafer and rotating and driving the wafer, and an upper electrode 4 which is movable toward the lower electrode 1 and passes injected chemical solution into the lower electrode 1 are provided. A wet process is carried out with applying a voltage between the lower electrode 1 and the upper electrode 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor process and a wet processing apparatus used for semiconductor manufacturing.

  Until now, in the wet process of a semiconductor device, a cleaning or etching process has been performed by immersing a wafer in a chemical solution based on an acid / alkali or jetting a chemical solution onto a rotating wafer.

On the other hand, in the removal of particles on the wafer, the conventional substrate material is etched by about 1 nm, the particles are lifted off from the substrate, and repulsion due to the zeta potential of the cleaning liquid is used to suppress reattachment and clean the wafer surface. It was. In the case of rinsing with pure water in the single-wafer wet process, static electricity is generated, which causes dissolution of Cu wiring and the like. This static electricity is generated by friction between the two because ultrapure water is an insulator and an insulating material such as a silicon oxide film is also present on the wafer. That is, in the case of pure water rinsing in the single wafer type wet processing, a phenomenon occurs in which the metal portion is melted regardless of the contact of different materials. In order to suppress such electrostatic friction, it has been proposed to use reduced water as conductive rinse water (see Patent Document 1).
JP 2002-373879 A

  However, the conventional wet process has the following problems. That is, in a semiconductor device having a thickness of 65 nm or more, various kinds of metals are mounted, and the problem of corrosion is becoming obvious at the contact portion of different materials during wet processing. The same applies to the rinsing method using the above-mentioned reduced water.

  On the other hand, removal of fine particles (particle size of 50 nm or less) on the wafer is extremely difficult. In other words, in advanced devices of 65 nm and later, there is no solution at present because the etching loss of the substrate is suppressed to <0.2 nm or less and fine particles of 50 nm or less are also removed. Note that microparticles of 70 nm or less do not repel due to zeta potential and are difficult to remove.

  An object of the present invention is to provide a semiconductor process and a wet processing apparatus that solves the above-described problems, prevents corrosion that occurs at the contact portion of different materials during wet processing, and enables removal of fine particles on the wafer. It is in.

  In order to solve the above-mentioned problems, the invention of claim 1 is a semiconductor process characterized in that, in a semiconductor process used in cleaning of a semiconductor manufacturing process, a wet process is performed while a voltage is applied to the wafer. The invention of claim 2 is a semiconductor process characterized in that light is blocked during the wet process in a step before the wiring portion is formed by the semiconductor manufacturing step. According to a third aspect of the present invention, there is provided a first electrode portion for electrostatically adsorbing a wafer and rotationally driving the wafer, and a chemical solution which is movable toward the first electrode portion and injected, to the first electrode portion. And a wet processing apparatus that performs wet processing while applying a voltage between the first electrode portion and the second electrode portion. According to a fourth aspect of the present invention, in the wet processing apparatus according to the third aspect, the second electrode portion has at least one through hole. According to a fifth aspect of the present invention, in the wet processing apparatus according to the third or fourth aspect, the side surface of the first electrode portion includes a side wall portion that can be attached in close contact, and the second electrode portion is the first electrode portion. It is possible to move in the side wall part attached to. According to a sixth aspect of the present invention, there is provided a first electrode portion that electrostatically attracts a wafer and rotationally drives the wafer, a brush portion that contacts an end surface of the wafer electrostatically attracted to the first electrode portion, and the brush portion And a chemical solution supply unit for supplying a chemical solution to the brush portion of the second electrode unit, and a first electrode unit and a first electrode unit. The wet processing apparatus is characterized in that a chemical solution is injected into the brush portion while applying a voltage between the two electrode portions and wet processing is performed. According to a seventh aspect of the present invention, there are provided a first electrode portion and a second electrode portion comprising a brush portion that contacts an end surface of a rotating wafer, and a rotating shaft portion that rotates the brush portion and applies a voltage. A chemical solution supply unit that supplies a chemical solution to at least one brush unit of the first electrode unit and the second electrode unit, while applying a voltage between the first electrode unit and the second electrode unit. A wet processing apparatus is characterized in that a chemical solution is supplied to a brush unit to perform wet processing. According to an eighth aspect of the present invention, in the wet processing apparatus according to any one of the third to seventh aspects, a blocking means for blocking light during the wet processing is a step before forming the wiring portion by the semiconductor manufacturing process. It is characterized by providing.

  In the present invention, a wafer is electrostatically adsorbed in a wet processing apparatus, and a positive or negative voltage is applied to the wafer. In this case, the positive / negative of the application is controlled by the processing step.

  In the present invention, corrosion can be suppressed by performing wet treatment while applying a voltage to the wafer. Moreover, the removal performance of fine particles is improved by performing a wet process while applying a voltage to the wafer. In other words, according to the principle of the present invention, the potential of the wafer is forcibly controlled to electrically repel the adhered particles and suppress reattachment. Moreover, the corrosion potential of the device constituent material (particularly metal) can be relaxed, and corrosion between different metals (galvanic corrosion) can be suppressed. Further, in the front-end process using a metal gate, since the corrosion of the metal gate can be suppressed by blocking the light, it is also important to block the light during processing.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
A single-wafer electric field wet processing apparatus used in this embodiment is shown in FIG. The single-wafer electric field wet processing apparatus shown in FIG. 1A includes a lower electrode 1, a rotating shaft 2, a side cup 3, an upper electrode 4, a chemical solution injection tube 5, and a voltage generator 6. A rotating shaft 2 is attached to the center of one surface of the disk-shaped lower electrode 1. The lower electrode 1 is rotated by the rotating shaft 2. The other surface of the lower electrode 1 is for placing the wafer 101 thereon. That is, the lower electrode 1 electrostatically attracts the wafer 101 and applies a positive or negative voltage to the wafer. A cylindrical side cup 3 can be attached to the side surface of the lower electrode 1 in a close contact state. The upper electrode 4 is a mesh electrode having a large number of through holes or an electrode having through holes formed by punching. FIG. 1B shows the upper electrode 4 in which the through hole 4A is opened by punching. As a result, the upper electrode 4 causes the chemical liquid injected from the chemical liquid injection tube 5 to flow toward the wafer 101 placed on the lower electrode 1. The upper electrode 4 is movable in the A direction. The upper electrode 4 is made of Pt or the like. The voltage generator 6 applies a voltage between the lower electrode 1 and the upper electrode 4. In this embodiment, the voltage of the voltage generator 6 is applied to the lower electrode 1 through the rotating shaft 2. For electrical connection between the rotating rotating shaft 2 and the voltage generating device 6, a method of connecting the rotating shaft 2 to the rotating shaft 2 using a brush on a lead wire electrically connected to the voltage generating device 6, or the rotating shaft 2 is supported. For example, there is a method of connecting a lead wire to a bearing.

  According to this single wafer type electric field wet processing apparatus, during processing, the side cup 3 puts the chemical solution on the wafer 101, and the upper electrode 4 which is the upper mesh electrode descends and comes into contact with the chemical solution. At the time of rinsing after the chemical solution treatment, the cover of the side cup 3 is removed, and the rinse solution is injected into the chemical solution injection tube 5 to perform the treatment. The applied voltage between the lower electrode 1 and the upper electrode 4 applied by the voltage generator 6 is preferably 1.8 V or less so as not to cause electrolysis. This is to suppress the generation of bubbles due to electrolysis. Further, not only a direct current is applied using the voltage generator 6, but an alternating current based on a direct current may be applied according to the processing purpose.

  Such a single wafer electric field wet processing apparatus is used for etching as follows. From the 45 nm generation onward, a metal gate is being mounted on the gate material. Here, an example in which a TiN film is used in the structure shown in FIG. In the case where the portion indicated by the broken line circle C1 of the underlying High-K film (HfSiO) is etched away with a 0.5% DHF solution, that is, when a wet process for removing the excess High-K film is performed, In this method, side etching as shown by a broken-line circle C2 occurs in the vicinity of TiN of the poly-Si film. This is because when a chemical solution is touched in a state where different materials are in contact, Poly-Si becomes a (+) electrode and TiN becomes a (-) electrode, and local cell effect (galvanic) corrosion occurs.

  However, by using the single-wafer type electric field wet processing apparatus of this embodiment and applying a (+) potential to the substrate side (Si sub.), Side etching as shown in FIG. Therefore, the etching removal of the High-K film can be completed. FIG. 3 shows the relationship between the potential applied to the substrate and the side etching amount. It can be seen that the side etching amount can be significantly suppressed by increasing the applied voltage.

  In addition, the amount of etching can be suppressed by blocking light during processing. In particular, in a back-end process in which a wiring portion is formed on the wafer 101 in the semiconductor manufacturing process, light is blocked and wet processing is performed in order to suppress galvanic corrosion. On the other hand, there is no device that actively blocks light as a wet processing device in the front end process until the wiring portion is formed. However, in the front-end process using a metal gate, since the corrosion of the metal gate can be suppressed by blocking the light with a light blocking device (not shown), it is also important to block the light during processing. . In the case where light was blocked while no bias was applied to the substrate, the etching amount could be suppressed to 1/10 that of irradiation with 1K lux light. Therefore, the voltage can be suppressed when biasing to the substrate.

(Embodiment 2)
FIG. 4 shows the substrate applied voltage dependence of the oxide film (SiO 2) etching amount when the single wafer electric field wet processing apparatus of the first embodiment is used. The etching amount of the SiO2 film by DHF (100 ppm) has no dependency on the applied potential (negative) of the substrate, but DHF (100 ppm) added with a cationic surfactant (50 ppm) is etched together with the applied voltage. The amount can be suppressed. This is because the hydrophilic group (+) of the cationic surfactant can be adsorbed to the SiO2 film by the negative potential of the substrate to protect the surface and suppress etching of the SiO2 film by HF ions. HF ions are required to dissolve residues and dust. However, when it is not desired to etch the SiO 2 film of the substrate (necessary for the 45 nm generation gate oxide film formation process), the substrate bias is controlled in this way. After the cleaning step is completed, the adsorbed surfactant can be effectively removed by applying a reverse bias in the rinsing step.

(Embodiment 3)
The fine particles of 70 nm or less adhering to the wafer are difficult to remove by the conventional cleaning technology, and the removal rate can be increased unless the etching amount of the substrate is increased or when powerful ultrasonic waves are used in combination. Can not. However, with the miniaturization, it is necessary to suppress the etching amount of the substrate, and from the viewpoint of suppressing the damage collapse to the fine pattern, it has become difficult to perform cleaning with ultrasonic waves. In such a situation, physical cleaning has been attempted based on pure water, but it is difficult to achieve both removal of fine particles and suppression of damage.

  Therefore, in this embodiment, the single wafer type electric field wet processing apparatus of Embodiment 1 is used, and the cleaning process is performed with a bias applied to the substrate. FIG. 5 shows the number of fine particles attached. FIG. 5 shows the result of an immersion experiment using silica particles and the number of adhered particles in a specific area measured by AFM. It can be seen that adhesion of fine particles can be suppressed by applying a voltage (1.5 V) using the single-wafer electric field wet processing apparatus of the first embodiment.

  In an experiment for removing negatively charged silica particles from a wafer, in the conventional technique, the removal performance of particles of 70 nm or less deteriorates rapidly. On the other hand, according to the single-wafer electric field wet processing apparatus of the first embodiment, when the voltage generator 6 performs processing while applying a bias of −1 V to the substrate, particles detached from the substrate by DHF (1 ppm). Are removed without reattachment due to charge repulsion.

  In this embodiment, it is also possible to perform a cleaning process by applying a bias to the substrate with the side cup 3 of the single-wafer electric field wet processing apparatus removed.

(Embodiment 4)
FIG. 6 shows a single-wafer type electric field wet processing apparatus used in this embodiment. The single-wafer electric field wet processing apparatus of FIG. 6 includes a lower electrode 11, a rotating shaft 12, a bevel brush 13, a chemical solution injection tube 14, and a voltage generator 15. The lower electrode 11, the rotating shaft 12, the chemical solution injection pipe 14, and the voltage generator 15 of the single-wafer electric field wet treatment apparatus according to this embodiment are the same as the lower electrode 1 of the single-wafer electric field wet treatment apparatus according to the first embodiment Since they are the same as the shaft 2, the chemical solution injection pipe 5, and the voltage generator 6, these descriptions are omitted.

  The bevel brush 13 includes a brush portion 13A and an upper shaft electrode portion 13B. The upper shaft electrode portion 13B is a rotating shaft that rotatably supports the brush portion 13A, and is made of a conductive material. The bevel brush 13 is preferably a metal coated with Pt or a metal coated with diamond doped with boron at a high concentration. The upper shaft electrode portion 13B is applied with a negative voltage by the voltage generator 15. The electrical connection between the upper shaft electrode portion 13B and the voltage generator 15 is the same as the electrical connection between the rotating rotating shaft 2 and the voltage generator 6 as described in the first embodiment.

  The 8-shaped brush portion 13A removes an excess film on the bevel (end surface) of the wafer 101 while rotating by the upper shaft electrode portion 13B. A chemical solution is injected from the chemical solution injection tube 14 into the brush portion 13A. PVA (polyvinyl alcohol) porous (sponge) material or the like is used as the material of the brush portion 13A, and the chemical solution soaks into the brush portion 13A. The brush portion 13A is detachable and contacts the wafer 101 only during bevel processing. In addition, as the shape of the brush portion 13A, there are various shapes such as a cylindrical shape in addition to the figure 8 shape.

  According to the process using this single-wafer electric field wet processing apparatus, processing is performed while the brush portion 13A of the bevel brush 13 is in contact with the wafer 101. In this case, both the wafer 101 and the brush portion 13A are rotated. The wafer 101 is brought into contact with the lower electrode 11 applied positively by the voltage generator 15, and the upper shaft electrode part 13 </ b> B that is the rotation axis (conductive substance) of the bevel brush 13 is applied negatively. The chemical solution from the chemical solution injection tube 14 soaks into the brush portion 13 </ b> A of the bevel brush 13, and a current flows between the upper shaft electrode portion 13 </ b> B of the bevel brush 13 and the wafer 101. A material that becomes a positive electrode is easily ionized and promotes dissolution. Further, since the brush portion 13A is detachable, it is brought into contact with the wafer only during the bevel processing.

  As described above, in this embodiment, the excessive film on the bevel (end face) of the wafer 101 is removed while applying an electric field to the substrate. In particular, with a conventional chemical solution alone, a film that is difficult to dissolve is dissolved and removed with a diluted chemical solution while an electric field is applied to the substrate. As shown in FIG. 7, the TaN film can achieve an etching rate of only about 5 nm / min with 50% hydrofluoric acid. However, as shown in the substrate applied voltage dependency of the etching rate of the TaN film when 5% hydrofluoric acid is used (FIG. 7), dissolution of the film is promoted by applying an electric field, and etching can be performed even with a diluted solution. It becomes possible. Therefore, the amount of chemical solution used can be greatly reduced, and processing can be performed in a short time.

  In this embodiment, an example in which the TaN film is removed with an HF solution as the film to be removed has been described. However, a hydrochloric acid solution, a hydrofluoric acid solution, a sulfuric acid solution, or the like is applied to a metal film such as Pt, Ru, or TaO. May be. The metal film is not limited to the above, but covers all transition metals and noble metals. Further, dissolution can be promoted by applying a voltage to the substrate using an HF solution to which an organic solvent is added even for SiOC, SiCN, BCN, or the like of the insulating film. It is considered that this is because the wafer substrate itself becomes an electrode and active oxygen is generated, so that dissolution of the film can be promoted.

  The background of the process using the single-wafer electric field wet processing apparatus according to this embodiment is as follows. In the Cu wiring forming process, the metal film (Cu film) adhering to the bevel portion of the wafer is brought into cross contamination due to contact with the carrier case or the like. Therefore, the metal film on the bevel (end face) is shown in FIG. Need to be removed. Such bevel Cu film removal has already been put to practical use. The Cu film can be easily dissolved and removed with a chemical solution such as diluted hydrogen sulfate aqueous solution, but the barrier metal such as TaN can be removed only with a concentrated HF chemical solution, and the low K film SiOC composition film can be easily etched. There is no. The film wrapping around the bevel proceeds to the next process while leaving it as it is.

  When the remaining films are stacked at the bevel portion in this way, peeling occurs due to poor adhesion. The peeled dust not only adheres to the wafer surface, but also comes into contact with the teeth and falls and adheres to the wafer under the peeling in the FOUP, resulting in a reduction in the yield of the product and frequent problems. On the other hand, recently, double brushes that can efficiently care for bevels using only pure water have been reported, and technological development aimed at further purification has been promoted. I can't. However, according to the process using the single-wafer type electric field wet processing apparatus according to this embodiment, the film can be dissolved and removed with a diluted chemical solution while an electric field is applied to the substrate.

  In this embodiment, the chemical solution injection tube 14 is provided on one bevel brush 13, but the chemical solution injection tube 14 may be provided on both bevel brushes 13. Furthermore, the number of bevel brushes 13 and chemical solution injection pipes 14 may be one or more.

(Embodiment 5)
A single wafer type electric field wet processing apparatus used in this embodiment is shown in FIG. In FIG. 9, components that are the same as or the same as those of the fourth embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. In the single-wafer electric field wet processing apparatus of FIG. 9A, a holding table 11A for holding the wafer 101 is provided instead of the lower electrode 11 of the fourth embodiment. Instead of the two bevel brushes 13, a cathode brush 16 composed of a brush part 16A and a shaft electrode part 16B and an anode brush 17 composed of a brush part 17A and a shaft electrode part 17B are provided. The cathode brush 16 is the same as the bevel brush 13 of the fourth embodiment, but in this embodiment, the shaft electrode portion 16B is connected to the cathode side of the voltage generator 15. The anode brush 17 is the same as the bevel brush 13, but in this embodiment, the shaft electrode portion 17 </ b> B is connected to the anode side of the voltage generator 15.

  As shown in FIG. 9B, the brush interval between the cathode brush 16 and the anode brush 17 is arranged at an interval of about 30 mm. By applying a voltage to the cathode brush 16 and the anode brush 17, the metal that contacts the bevel (end surface) of the wafer 101 is dissolved by anodic oxidation. The brush interval is preferably in the range of about 5 mm to 100 mm, and the interval and the contact pressure to the wafer can be freely adjusted. FIG. 10 shows the results of measuring the etching rate of the Ru film and the TaN film by applying a voltage of 5V. It can be seen that the HCl solution can be sufficiently dissolved even at a low concentration of 0.5% or less.

  Since Ru and Ta form complex ions with Cl, it is considered that they were dissolved and removed together with the anodic oxidation. Further, since the practical film thickness is 20 nm or less, it can be said that the Ru film can be removed within 1 min. When the polarity of the electrode of the voltage generating device 15 is constant, the sponge, that is, the brush portion 16A and the brush portion 17A are contaminated with the dissolved metal component, and therefore the polarity can be periodically reversed. In this experiment, 10 μL of diluted hydrochloric acid was dropped at an interval of 5 seconds and a voltage of 5 V was applied. However, the dropping interval, the dropping amount, and the applied voltage may be changed as appropriate. Instead of a constant voltage, a constant current method may be used. The solution to be dropped is not limited to hydrochloric acid but may be an acidic chemical solution such as sulfuric acid or nitric acid or an alkaline solution such as ammonia. Further, hydrogen peroxide water may be mixed in these solutions. However, hydrofluoric acid is desirably avoided because it dissolves the Si substrate.

  BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the single wafer type electric field wet processing apparatus used in Embodiment 1 of this invention, Fig.1 (a) is a fragmentary sectional view which shows a single wafer type electric field wet processing apparatus, FIG.1 (b) is a lower part. It is a perspective view which shows an electrode and an upper electrode.   FIG. 2A is a diagram showing a state of etching, FIG. 2A is a diagram showing a case where a conventional single-wafer electric field wet processing apparatus is used, and FIG. 2B is a diagram showing the use of the single-wafer electric field wet processing apparatus according to the present invention. FIG.   It is a figure which shows the relationship between the electric potential applied to a board | substrate, and the amount of side etching.   It is a figure which shows the substrate application voltage dependence of the oxide film (SiO2) etching amount.   It is a figure which shows the reattachment number of microparticles | fine-particles.   It is a figure which shows the single wafer type electric field wet processing apparatus used in Embodiment 4 of this invention.   It is a figure which shows the substrate application voltage dependence of the etching rate of a TaN film | membrane.   It is explanatory drawing of the bevel film | membrane removal process of a wafer.   It is a figure which shows the single wafer type electric field wet processing apparatus used in Embodiment 5 of this invention, Fig.9 (a) is a figure which shows the structure of a single wafer type electric field wet processing apparatus, FIG.9 (b) is a wafer. It is a figure which shows the position of the bevel brush with respect to.   It is a figure which shows the dependence of the melt | dissolution rate of Ru film | membrane and TaN film | membrane with respect to HCl (hydrochloric acid) density | concentration.

Explanation of symbols

1, 11 Lower electrode (first electrode part)
2, 12 Rotating shaft 3 Side cup (side wall)
4 Upper electrode (second electrode)
4A Through-hole 5 Chemical solution injection pipes 6 and 15 Voltage generator 13 Bevel brush (second electrode part)
14 Chemical injection pipe (chemical supply unit)
13A Brush portion 13B Upper shaft electrode portion 16 Brush for cathode (first electrode portion)
16A Brush part 16B Shaft electrode part (Rotating shaft part)
17 Anode brush (second electrode)
17A Brush part 17B Shaft electrode part (Rotating shaft part)

Claims (8)

In semiconductor processes used for cleaning semiconductor manufacturing processes,
A semiconductor process characterized by performing wet processing while applying a voltage to a wafer.   A semiconductor process characterized in that light is blocked during a wet process in a process before forming a wiring portion in a semiconductor manufacturing process. A first electrode unit that electrostatically attracts the wafer and rotationally drives the wafer;
A second electrode part that is movable toward the first electrode part and passes the injected chemical solution through the first electrode part,
A wet processing apparatus that performs wet processing while applying a voltage between a first electrode portion and a second electrode portion.   The wet processing apparatus according to claim 3, wherein the second electrode portion has at least one through hole. Provided with a side wall part that can be attached in close contact with the side surface of the first electrode part
The wet processing apparatus according to claim 3 or 4, wherein the second electrode part is movable in a side wall part attached to the first electrode part. A first electrode unit that electrostatically attracts the wafer and rotationally drives the wafer;
A second electrode unit comprising a brush unit in contact with an end face of the wafer electrostatically attracted to the first electrode unit, and a rotating shaft unit for rotating the brush unit and applying a voltage;
A chemical solution supply unit for supplying a chemical solution to the brush portion of the second electrode unit,
A wet processing apparatus that performs wet processing by injecting a chemical into the brush portion while applying a voltage between the first electrode portion and the second electrode portion. A first electrode portion and a second electrode portion comprising a brush portion in contact with an end surface of a rotating wafer and a rotating shaft portion for rotating the brush portion and applying a voltage;
A chemical solution supply unit that supplies a chemical solution to at least one brush portion of the first electrode unit and the second electrode unit;
A wet processing apparatus that performs wet processing by supplying a chemical solution to a brush portion while applying a voltage between a first electrode portion and a second electrode portion.   8. The wet processing apparatus according to claim 3, further comprising: a blocking unit configured to block light during the wet process in a process before forming the wiring portion in the semiconductor manufacturing process.

Images