JP2003027288A - Plating equipment and plating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To plate a work while preventing air bubbles from remaining on the surface to be plated of the work, to make maintenance free and to prevent the work from acting as a source for generating particles. SOLUTION: The plating equipment has a holding section 14 which freely attachably and detachably holds the work W and plates the work by contacting or immersing the surface to be plated of the work W with or into a plating solution 10 and an anode 16 which is arranged in a position confronting the work W held by the holding section 14. A liquid 38 which touches the periphery of the surface to be plated of the work W when the work W is held, is internally held and has electrical conductivity, and a plurality of power source contact sections 26 which are immersed into this liquid 38 and feed electricity to the surface to be plated of the work W through contacts 32 are arranged by being spaced from each other in the holding section 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus and a plating method, and more particularly to a plating apparatus used for filling a fine wiring pattern (recess) formed on a semiconductor substrate with a metal such as copper (Cu). And a plating method.

[0002]

2. Description of the Related Art In recent years, as a metal material for forming a wiring circuit on a semiconductor substrate, copper (Cu) having a low electric resistivity and a high electromigration resistance has been remarkably used in place of aluminum or an aluminum alloy. Has become. This kind of copper wiring is generally formed by embedding copper inside the fine recesses provided on the surface of the substrate. As a method for forming this copper wiring, there are methods such as CVD, sputtering, and plating. In any case, unnecessary copper is formed by chemical mechanical polishing (CMP) by forming a copper film on almost the entire surface of the substrate. To remove.

FIG. 4 shows an example of manufacturing a copper wiring board W of this kind in the order of steps. As shown in FIG. 4A, a conductive layer 1a is formed on a semiconductor substrate 1 on which a semiconductor element is formed. To Si
An oxide film made of O ₂ or an insulating film 2 such as a Low-K material film is deposited, a contact hole 3 and a trench 4 for wiring are formed by a lithography / etching technique, and a barrier film 5 made of TaN or the like is formed thereon. Further, a seed layer 7 is formed thereon as a power feeding layer for electrolytic plating.

Then, as shown in FIG. 4B, the substrate W
By plating the surface of the substrate with copper, the contact hole 3 and the groove 4 of the substrate W are filled with copper, and the copper film 6 is deposited on the insulating film 2. After that, chemical mechanical polishing (CM
By P), the copper film 6 on the insulating film 2 is removed so that the surface of the copper film 6 filled in the contact hole 3 and the wiring groove 4 and the surface of the insulating film 2 are substantially flush with each other. Thereby, as shown in FIG. 4C, the wiring made of the copper film 6 is formed.

FIG. 5 shows an object to be processed (hereinafter referred to as a substrate) such as a semiconductor wafer by adopting a so-called face-down method.
1 shows a conventional general configuration of a plating apparatus that performs electrolytic plating on the surface of. This plating apparatus has a cylindrical plating tank 102 that opens upward and holds the plating solution 100 therein, and a position at which the substrate W is detachably held downward and the substrate W closes the upper opening of the plating tank 102. Substrate holder 1 to be placed in
04 and. Inside the plating tank 102, a flat plate-shaped anode plate (anode) 106 that is immersed in the plating solution 100 and serves as an anode electrode is horizontally arranged. on the other hand,
Conductor layer (seed layer) on the lower surface (surface to be plated) of the substrate W
S is formed, and the conductor layer S has a contact point with the cathode electrode at the peripheral portion thereof. A plating solution injection pipe 108 that forms an upward jet of the plating solution is connected to the center of the bottom of the plating tank 102, and a plating solution receiver 110 is arranged outside the top of the plating tank 102.

As a result, the substrate W is placed on the upper portion of the plating tank 102 while being held downward by the substrate holding portion 104, and the plating solution 100 is jetted upward from the bottom portion of the plating tank 102 so that the lower surface of the substrate W By applying a predetermined voltage from the plating power supply 112 between the anode plate 106 (anode electrode) and the conductor layer S (cathode electrode) of the substrate W while applying the jet of the plating solution 100 to the plating surface), the substrate W The plating film is formed on the lower surface of the. At this time, the plating solution 100 that overflows the plating tank 102 receives the plating solution receiver 110.
Recovered from.

Here, in order to protect the back surface of the substrate W from copper contamination, a so-called dry contact method is generally adopted as a method of energizing the plating power supply 112 to the substrate W.
That is, as shown in FIG. 6, a substrate chuck 120 that supports the substrate W downward by suction or the like, and a housing 122 that surrounds the periphery of the substrate chuck 120 and opens downward.
The substrate holding unit 104 is composed of the above. A substrate mounting portion 124 protruding inward in a ring shape is provided at the lower end of the housing 122, and a seal ring 126 having a steeple cross section is fixed to the upper surface of the substrate mounting portion 124 and supported by the substrate chuck 120. The substrate W is held by the substrate holder 104 in a watertightly sealed state by a seal ring 126 being pressed against the peripheral edge of the substrate so that the plating solution 100 does not wrap around to the back surface side of the substrate W.

Further, a plurality of contacts 128 are arranged outside the seal ring 126 in a ring shape at a predetermined pitch, and the seal ring 126 is pressed against the peripheral edge of the plated surface of the substrate to hold the substrate W on the substrate holding portion. When held at 104,
This contact 128 is brought into direct contact with the substrate W so that the substrate W
To the plating solution 1
I try not to touch 00.

[0009]

However, in the conventional plating apparatus of this type, when the substrate is held by the substrate holding portion and the substrate is lowered and the surface to be plated is brought into contact with the plating solution. The seal ring that protrudes into the plating solution and seals the plating solution and the substrate mounting portion block the escape of bubbles, leaving bubbles on the surface to be plated. in this way,
When plating is performed with air bubbles remaining on the surface to be plated, there is a problem that defects may occur in the plating film and the yield of devices may be affected. Although the substrate is also placed in the plating solution in a tilted state, it is difficult to prevent bubbles from remaining on the surface to be plated even when the substrate is tilted in this way.

A seal ring for preventing the escape of air bubbles
To prevent bubbles from remaining on the plated surface
Is the so-called
It is desirable to adopt the wet contact method. Only
However, if the wet contact method is adopted, it is a metal
The plating film also adheres to the contact surface, and
After applying heat treatment, reverse voltage is applied each time to clean the contact surface.
It is necessary to peel off the coating. Moreover, the peeled Cu layer
On is monovalent Cu⁺2Cu⁺
→ Cu⁰+ Cu²⁺ By the reaction of Cu⁰Party
Occurs, and the quality of the plated film is affected.

Even if the dry contact method is adopted, when the continuous operation is carried out for a long time, the plating solution wraps around the contact portion, the crystal of the plating solution adheres around the contact, and the generation source of particles is generated. Will be.

The present invention has been made in view of the above,
An object of the present invention is to provide a plating apparatus and a plating method capable of performing plating while preventing bubbles from remaining on the surface to be plated of the object to be processed, and being a maintenance-free source of particles. And

[0013]

According to a first aspect of the present invention, there is provided a holding portion for holding an object to be processed detachably and performing plating by contacting or immersing a surface of the object to be plated in a plating solution. An anode arranged at a position facing the object to be processed held by the holding part, the holding part being in contact with the peripheral edge of the plated surface of the object to be processed when the object to be processed is held, And a plurality of power source contact portions for supplying power to the surface to be plated of the object to be processed through the contact immersed in the liquid and the liquid having conductivity are arranged apart from each other. Is.

With this, when the object to be processed is lowered while the object to be processed is held by the holding part and the surface to be plated is brought into contact with the plating solution, the bubbles can be easily fed from between the power supply contact parts adjacent to each other. By allowing it to escape, it is possible to prevent bubbles from remaining on the plated surface. Moreover, by using a liquid that does not contain metal ions as the liquid having conductivity that fills the inside of the power contact portion, it is possible to prevent the contact surface from being plated. When supplying power to the plated surface of the object to be processed, the contact may be brought into direct contact with the surface of the object to be plated, or may be electrically contacted via a liquid having conductivity.

The invention according to claim 2 is characterized in that the holding portion is provided with a seal ring for sealing the peripheral portion of the back surface of the workpiece when the workpiece is held. The plating apparatus according to 1. As a result, it is possible to prevent the plating solution from flowing around the back surface of the object to be processed. Moreover, since the seal ring is provided on the back surface side of the object to be processed, the seal ring does not hinder the escape of air bubbles.

When a substrate is used as the object to be processed, a plating film is also formed on the bevel portion (edge portion) of the substrate. The plating film formed on the bevel portion (edge portion) in this way. The film may be removed later.

According to a third aspect of the present invention, the power source contact portion has a cylindrical sealing material, and the sealing material is
The plating apparatus according to claim 1 or 2, wherein the plating apparatus is arranged at a predetermined pitch along the contour of the object to be processed. This makes the flow of the plating solution smooth,
The escape of bubbles can be further improved.

According to a fourth aspect of the invention, a liquid supply path for supplying a conductive liquid to the inside of each of the power source contact portions is provided inside the holding portion, and the conductive liquid is The plating apparatus according to any one of claims 1 to 3, wherein the plating apparatus is a liquid in which components contained in the plating solution are added to water. With this, by supplying a conductive liquid to the inside of the power contact portion from the liquid supply path during plating to bring the pre-pressurized state, it is possible to prevent the plating solution from entering the inside of the power contact portion at all times. Fresh liquid can be supplied inside the power contact. Further, even if the conductive liquid in the power source contact portion is mixed in the plating solution, it is possible to prevent the liquid from affecting the plating solution. For example, when a copper sulfate plating solution containing copper sulfate and sulfuric acid in its composition is used as the plating solution, examples of this component include sulfuric acid and organic additives.

According to a fifth aspect of the present invention, there is provided a conductive liquid which comes into contact with the surface to be plated of the object to be processed, and a contact which is immersed in the liquid in a non-contact state with the object to be processed. The plating method is characterized in that the surface to be plated of the object to be processed is supplied with power to perform plating.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a plating apparatus according to an embodiment of the present invention. The overall configuration of this plating apparatus is almost the same as that shown in FIG. 5, for example, and the surface to be plated (surface) of an object to be processed (hereinafter referred to as a substrate) such as a semiconductor wafer is subjected to electrolytic copper plating, An example in which the copper wiring shown in 1 is formed will be described below.

This plating apparatus is, for example, a copper sulfate plating solution 1 which is opened upward and contains copper sulfate and sulfuric acid in its composition.
A plating tank 12 for holding 0 and a substrate W for detachably holding the substrate W downward (face down) and bringing the surface (surface to be plated) of the substrate W into contact with the plating solution 10 held in the plating tank 12 for plating. And a holding portion 14. Inside the plating tank 12, a flat anode plate (anode) 16 which is immersed in the plating solution 10 and serves as an anode electrode is horizontally arranged. On the other hand, on the lower surface (surface to be plated) of the substrate W,
The seed layer 7 (see FIG. 4) is formed.

The substrate holding section 14 has a substrate chuck 18 for supporting the substrate W by suction or the like, and a housing 20 surrounding the substrate chuck 18 and opening downward. On the lower surface of the substrate chuck 18, the substrate chuck 1
When the substrate is supported by 8, a seal ring 22 is attached, which is pressed against the peripheral portion of the back surface (upper surface) of the substrate W to seal it water-tightly and prevent the plating solution from flowing around to the back surface of the substrate W. Has been.

Further, a substrate mounting portion 24 projecting inwardly in a ring shape is integrally provided at the lower portion of the housing 20,
A plurality of power supply contact portions 26 are arranged at a predetermined pitch at predetermined positions along the circumferential direction of the substrate mounting portion 24. Further, a flow hole 20a through which the plating solution 10 flows is provided at a position facing each other between the power supply contact portions 26 adjacent to each other of the housing 20.

The power source contact portion 26 is for supplying power to the surface (surface to be plated) of the substrate W held by the substrate holding portion 14, and as shown in FIG. 2, a cylindrical sealing material 30, And a contact 32 disposed inside the sealing material 30.
4 is connected to the wiring 36 connected to the cathode. The anode of the plating power source 34 is connected to the anode plate (anode) 16. The height of the contact 32 is set so that when the substrate W is held by the substrate holding portion 14, a gap d is formed between the contact 32 and the substrate. Then, the inside of the sealing material 30 is filled with the conductive liquid 38,
When the substrate W is held by the substrate holding unit 14, the liquid 38 is brought into contact with the surface of the substrate W to supply power to the surface (plated surface) of the object W to be processed.

That is, if the voltage formed by the gap d between the contact 32 and the substrate W is extremely smaller than the voltage formed by the distance 1 between the substrate W and the anode plate 16, the substrate A negative potential required for plating is formed on the surface, and normal plating is performed. In this example, the substrate W and the anode plate 16 are electrically contacted with each other through the conductive liquid 38, but the contact 32 and the substrate W may be directly contacted with each other. Good.

Then, with the substrate W being held by the substrate holder 14, the substrate W is lowered and the surface of the substrate W (the surface to be plated) is brought into contact with the plating solution 10 held in the plating tank 12 to perform plating. When the surface of the substrate W is brought into contact with the plating solution 10, it is possible to prevent bubbles from remaining on the surface of the substrate W by allowing bubbles to easily escape from between the power supply contact portions 26 adjacent to each other. can do. Moreover, by using a liquid 38 having no metal ions as the conductive liquid 38, the contact 3
It is possible to prevent the surface of 2 from being plated.

Here, as the material of the contact 32,
Examples include platinum, which is a metal that is more precious than copper. Also,
The conductive liquid 38 is preferably a liquid obtained by adding a component contained in the plating solution 10 to water, whereby the conductive liquid 38 inside the power contact portion 26 is added to the plating solution 10. Even if mixed, the liquid 38 can be prevented from affecting the plating liquid 10. For example, when a copper sulfate plating solution containing copper sulfate and sulfuric acid in its composition is used as the plating solution 10, examples of this component include sulfuric acid and organic additives.

Further, inside the housing 20, a liquid supply passage 40 for supplying a conductive liquid 38 to the inside of each sealing material 30 of each power source contact portion 26 is provided, and the liquid supply passage 40 is made to pass therethrough. Liquid 38 to seal material 30
It is designed to be supplied inside. It is preferable that the liquid 38 is supplied from the liquid supply path 40 to the inside of the seal material 30 to be in a pre-pressurized state while the substrate W is held by the substrate holder 14 and plating is performed. It is possible to constantly supply a fresh liquid to the inside of the sealing material 30 while preventing the plating solution 10 from flowing into the inside of the sealing material 30. At this time, as described above, the liquid 38 having conductivity is used as the liquid 38 having conductivity by adding a component contained in the plating liquid 10 to water. It is possible to prevent the influence. Alternatively, the conductive liquid inside the sealing material 30 may be drawn out in vacuum every time the plating process is performed, and a fresh liquid may be supplied every time.

Next, a plating method using this plating apparatus will be described. First, the substrate holding part 14 is set to the plating solution 10.
The substrate W is placed above the liquid surface of the housing 20.
It is carried in the inside of the substrate and supported by the substrate chuck 18 by suction or the like. At this time, the back surface (upper surface) of the substrate W is sealed by the seal ring 22.
Is sealed in a watertight manner to prevent the plating solution 10 from flowing around to the back surface side of the substrate W. On the other hand, each sealing material 3
The inside of 0 is filled with the liquid 38 having conductivity. Then, the substrate chuck 18 is lowered, the sealing material 30 of the power supply contact portion 26 is brought into pressure contact with the peripheral portion of the surface (surface to be plated) of the substrate W, and the substrate W is held by the substrate holding portion 14.

In this state, the substrate holding part 14 holding the substrate W is lowered while being rotated as necessary to bring down the substrate W.
Is immersed in the plating solution 10. When the surface of the substrate W is brought into contact with the plating solution 10, since there is nothing protruding into the plating solution 10 between the power source contact portions 26 adjacent to each other, the plating solution 10 flows smoothly between them.
Air bubbles generated on the surface (the surface to be plated) of the substrate W easily escape to the outside by riding on the flow of the plating solution 10.

Next, while rotating the substrate W as required, a predetermined voltage is applied from the plating power source 34 between the anode plate 16 (anode electrode) and the power source contact portion 26, and the power source contact portion 26 is rotated. To the surface of the substrate W (the surface to be plated) to form a plating film on this surface. At this time, if necessary, the liquid 38 is supplied from the liquid supply passage 40 to the sealing material 3
It is supplied to the inside of 0 to be in a preload state. After the plating is finished, the voltage application from the plating power source 34 is stopped, the substrate W is raised together with the substrate holding unit 14, and only the substrate chuck 18 is raised together with the substrate. Transfer to the process.

In this embodiment, a cylindrical seal material is used to improve the escape of air bubbles. However, the entire outer peripheral surface of the substrate is kept in a dry contact state.
Power may be supplied by bringing a conductive liquid into contact with the substrate without bringing the metal into contact with the substrate.

[0033]

As described above, according to the present invention,
By holding the object to be processed in the holding part and lowering the object to be processed and bringing the surface to be plated into contact with the plating solution, bubbles can easily escape from between the power supply contact parts adjacent to each other. It is possible to prevent air bubbles from remaining on the surface to be plated, improve the quality of the plated film, and improve the device yield. Moreover, by using a liquid having no metal ions as the conductive liquid of the power contact part, it is possible to prevent the contact surface from being plated, so that the contact is maintenance-free and the contact is a source of particle generation. Can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing a plating apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an essential part showing an enlarged part of FIG.

3 is a cross-sectional view taken along the line AA of FIG.

4A to 4D are diagrams showing an example of forming a copper wiring by copper plating in the order of steps.

FIG. 5 is a schematic diagram showing an overall configuration of a conventional plating apparatus.

FIG. 6 is a cross-sectional view showing a substrate holder of a conventional plating apparatus.

[Explanation of symbols]

10 Plating solution 12 plating tank 14 Substrate holding part (holding part) 16 Anode plate (anode) 18 Substrate chuck 20 housing 22 Seal ring 24 Substrate placement section 24a distribution hole 26 Power contact section 30 sealing material 32 contacts 34 power supply 38 Liquid with conductivity 40 Liquid supply path

Claims (5)

[Claims] 1. A holding part for holding an object to be processed detachably, and a plating surface of the object to be processed being brought into contact with or immersed in a plating solution to perform plating, and a holding part facing the object to be processed held by the holding part. An anode arranged at a position, the holding portion is in contact with a peripheral portion of a plated surface of the object to be treated when the object to be treated is held, and a liquid having conductivity filled therein; A plating apparatus, wherein a plurality of power supply contact portions for supplying power to a surface to be plated of the object to be processed through the contacts immersed in the plate are arranged apart from each other. 2. The plating apparatus according to claim 1, wherein the holding portion is provided with a seal ring that seals a peripheral portion of the back surface of the object to be processed when the object is held. 3. The power supply contact portion has a cylindrical sealing material, and the sealing material is arranged at a predetermined pitch along the contour of the object to be processed. 2. The plating apparatus according to 2. 4. A liquid supply path for supplying a conductive liquid to the inside of each of the power source contact parts is provided inside the holding part, and the conductive liquid is contained in a plating solution. The plating apparatus according to any one of claims 1 to 3, which is a liquid in which components are added to water. 5. The plating is performed by supplying power to the plated surface of the object to be processed through a conductive liquid that comes into contact with the plated surface of the object to be processed and a contact immersed in the liquid. Plating method.