JP3415005B2 - Plating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for substrates, and more particularly to a plating apparatus for filling a wiring groove or the like formed in a semiconductor substrate with a metal such as copper (Cu).

[0002]

2. Description of the Related Art Conventionally, in order to form a wiring circuit on a semiconductor substrate, a film is formed on the surface of the substrate by sputtering or the like, and then a film is formed by chemical dry etching using a pattern mask such as a resist. Unnecessary parts were removed.

As a material for forming a wiring circuit,
Aluminum (Al) or aluminum alloy is used, but the wiring becomes thinner as the degree of integration increases,
Due to the increased current density, thermal stress and temperature rise occur.
This becomes more remarkable as Al or the like is diluted by stress migration or electromigration, and finally there is a risk of disconnection.

Therefore, in order to avoid excessive heat generation due to energization, it is inevitably required to employ a material having higher conductivity for wiring formation. Among the current materials, copper (Cu) and silver (Ag) are materials that have a smaller electrical resistivity than Al-based materials.

However, it is difficult to dry-etch Cu or its alloys, and it is difficult to adopt the above-described method of forming a pattern on the entire surface and then forming a pattern. Therefore, a process in which a groove for wiring having a predetermined pattern is formed in advance and Cu or an alloy thereof is filled therein can be considered. According to this, a step of removing the film by etching is not necessary, and a polishing step for removing the surface step may be performed if necessary. Further, there is an advantage that a portion called a plug that connects the upper and lower sides of the multilayer circuit can be formed at the same time.

[0006]

However, the shape of such a wiring groove or plug has a considerably high aspect ratio (ratio of depth to diameter or width) as the wiring width becomes finer, and therefore, in sputtering film formation. It was difficult to fill the metal uniformly. Further, although a vapor phase growth (CVD) method is used as a film forming means for various materials, it is difficult to prepare a suitable gas raw material with Cu or its alloy, and when an organic raw material is adopted. However, there is a problem in that carbon (C) is mixed into the deposited film to improve the migration property.

Further, a method of electroless or electrolytic plating by immersing the substrate in a plating solution has been proposed.
Since liquid circulation and ion supply to the bottom of the groove or hole are insufficient, film growth at the bottom is slower than at the edge of the groove and the top of the groove is clogged, creating a void at the bottom. As a result, uniform filling was difficult.

In view of the above-mentioned circumstances, the present invention is a plating which can efficiently and uniformly fill a fine recess such as a groove for fine wiring with a material having a small electric resistivity such as copper or a copper alloy. The purpose is to provide a device.

[0009]

According to a first aspect of the present invention, there is provided a plating tank for holding a plating solution, a holding table for holding a substrate in the plating tank, and the substrate in the plating solution in the plating tank. Of ultrasonic waves that generate ultrasonic waves substantially parallel to the surface to be processed of the plating tank and the ultrasonic wave vibrator that forms a standing wave between the walls of the plating tank and the holding table are moved along the surface of the substrate to be processed. A plating apparatus having a moving means.

As a result, the ultrasonic transducer is
When operated at a frequency of 10 Hz to 10 MHz and ultrasonic vibration is applied to the plating solution, the plating solution located on the upper surface of the board is parallel to the board between the ultrasonic vibrator and the side wall facing the board. Standing waves of propagating compression waves are formed. A large amplitude of the compression wave is formed at the position corresponding to the antinode of the standing wave, and the pressure fluctuation associated therewith promotes the flow and replacement of the plating solution in the groove of the substrate, thereby performing good plating in the groove. The position of the antinode of the standing wave is moved evenly to each part on the substrate by the movement of the substrate by the moving means, so that the plating speed in the groove of each part of the substrate is uniformly improved. The plating method may be electrolytic plating or electroless plating.

The invention according to claim 2 is the plating apparatus according to claim 1, wherein the moving means rotates the holding table. A non-uniform plating rate can be avoided with a relatively simple method.

The invention according to claim 3 is the plating apparatus according to claim 1, wherein the holding table is provided with heating means for heating the substrate. For example,
By heating the semiconductor wafer to around 100 ° C., the mass diffusion is improved and the viscosity is lowered, so that the mass transfer is promoted in the vicinity of the wafer surface.

The invention according to claim 4 is the plating apparatus according to claim 1, characterized in that the holding table is further vibrated vertically. As a result, the effect of promoting the flow of the plating solution to the fine grooves due to ultrasonic vibration is further enhanced, and the efficiency of plating adhesion to these is improved.

According to a fifth aspect of the present invention, after plating is performed using the plating apparatus according to any of the first to fourth aspects, unnecessary portions of the metal adhering to the substrate are polished by a chemical mechanical polishing apparatus. It is a method of processing a substrate, which is characterized in that it is removed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. This plating apparatus is a plating tank 10 configured as a substantially rectangular parallelepiped container by four side walls 10a, 10b, 10c, 10d and a bottom plate 10e.
A rotatable holder 14 supported by a shaft 12 that penetrates the bottom plate 10e, and one side wall 10 of the plating tank 10.
and an ultrasonic transducer 16 arranged along a and generating ultrasonic vibration toward the opposing side wall 10c. A seal mechanism 20 is provided on the bottom plate penetrating portion 18 of the shaft body 12 to prevent the plating solution from leaking.

A fixing ring 24 is attached to the upper part of the holding table 14 so as to fix the substrate W to the back surface thereof in a liquid-tight manner via a seal ring 22 so that the plating solution does not rotate.
A cavity 28 for accommodating the heater 26 is formed inside the holding table 14, and the cavity 28 communicates with a hollow portion 30 of the shaft body 12 in which a power supply cable for the heater 26 is arranged. The shaft 12 is connected to a rotation driving motor 36 via a pulley 32 and a pulley belt 34, and is rotated at a controlled rotation speed. The shaft 12 is also provided with a vibrating mechanism 38 that vibrates the shaft 12 up and down.

The plating tank 10 is provided with a plating solution flow passage (not shown) for maintaining the concentration and temperature of the plating solution constant, and a path for adding a new plating solution and heating or cooling are provided in this passage. A route is provided.

The operation of the plating apparatus configured as described above will be described in the case of plating Cu or its alloy for forming a wiring circuit on a semiconductor substrate. As shown in FIG. 3A, the substrate W to be processed has a conductive layer 52 and SiO ₂ on a semiconductor substrate 50 on which a semiconductor element is formed.
After depositing an insulating layer 54 made of, a contact hole 56 and a wiring groove 58 are formed by a lithographic etching technique, and a barrier layer 6 made of TiN or the like is formed thereon.
0 is formed.

The substrate W as described above is placed on the holding table 14,
This is maintained at a predetermined temperature close to 100 ° C. by the heater 26 to promote diffusion of substances in the plating solution on the surface of the substrate and lower the viscosity of the plating solution. Further, the plating solution in the plating tank 10 is also maintained at a predetermined temperature. Then, the ultrasonic vibrator 16 is operated at a frequency of, for example, 1 Hz to 10 MHz to apply ultrasonic vibration to the plating solution. Further, the motor 36 is driven to move the holding table 14 to, for example, 15 to 120r.
It is rotated at a rotation speed of about pm, and the vibrating mechanism 38 is operated to move the holding table 14 up and down in a cycle of about 1 to 3 times per rotation.

Due to the oscillation of the ultrasonic oscillator 16, as shown in FIG. 2, the plating liquid located on the upper surface of the substrate W is parallel to the substrate W between the ultrasonic oscillator 16 and the opposite side wall 10c. Standing waves of propagating compression waves are formed. As a result, a large compression wave amplitude is formed at the position corresponding to the antinode of the standing wave, which causes a large pressure fluctuation, which promotes the flow and replacement of the plating solution in the groove 58 of the substrate W, thereby improving the good inside Plating is performed. The efficiency of plating is
It is also accelerated by the vertical vibration of the holding table 14, that is, the substrate W by the vibrating mechanism 38.

On the other hand, since such pressure fluctuation is small at the position of the node of the standing wave, the plating is not promoted. However, since the position of the antinode of the standing wave moves uniformly to each part on the substrate W by the rotation of the holding table 14, the position of the antinode of the standing wave is biased to improve the plating rate in the groove. Non-uniformities are avoided. The movement of the holding table 14 may be an operation of reciprocating in the traveling direction of the ultrasonic wave.

By the above liquid phase plating process, FIG.
As shown in FIG. 3, the contact hole 56 and the groove 58 of the semiconductor substrate W are filled with Cu, and Cu is formed on the insulating film 54.
Deposit layer 62. After that, chemical mechanical polishing (CM
By P), the Cu layer on the insulating film 54 is removed so that the surface of the Cu layer 62 filled in the contact hole 56 and the wiring groove 58 and the surface of the insulating film 54 are substantially flush with each other. As a result, the wiring made of the Cu layer 62 is formed as shown in FIG.

[0023]

As described above, according to the present invention,
The pressure fluctuation formed in the plating solution by the ultrasonic vibrator promotes the flow and replacement of the plating solution in the groove of the substrate,
By moving the substrate by the moving means, the plating rate in the groove of each part of the substrate can be uniformly improved. Therefore, it is possible to efficiently and uniformly fill a material having a small electric resistivity such as copper or a copper alloy into a minute depression such as a groove for minute wiring, and therefore, to realize a semiconductor integrated circuit of high density. It is possible to provide a useful technique for promoting the conversion.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall outline of a plating apparatus according to an embodiment of the present invention.

2 (a) is a plan view and FIG. 2 (b) is a side view for explaining the operation of the plating apparatus according to the embodiment of FIG.

FIG. 3 is a cross-sectional view showing an example of a step of performing plating by the plating apparatus of the present invention.

[Explanation of symbols]

10 plating tank 10a, 10b, 10c, 10d Side wall 10e Bottom plate 12 shafts 14 holding table 16 Ultrasonic transducer 18 Bottom plate penetration 20 Sealing mechanism 22 Seal ring 24 fixing ring 26 heater 28 cavities 30 hollow 32 pulley 34 pulley belt 36 motor 38 Vibration device 54 insulating film 56 contact holes 58 groove 62 Cu layer W board

Continuation of the front page (56) References JP-A 61-120343 (JP, A) JP-A 50-3039 (JP, A) JP-A 8-244138 (JP, A) JP-A 8--126872 (JP , A) JP 8-23166 (JP, A) JP 7-286278 (JP, A) JP 7-101715 (JP, A) JP 6-212441 (JP, A) JP 3-36280 (JP, A) JP-B-52-39767 (JP, B2) JP-B-52-21977 (JP, B2) European Patent Application Publication 901153 (EP, A2) (58) Fields searched (Int. Cl. ⁷ , DB name) C23C 18/31 C25D 5/20 C25D 7/12 C25D 21/10 H01L 21/288

Claims (5)

(57) [Claims] 1. A plating tank for holding a plating solution, a holding table for holding a substrate in the plating tank, and ultrasonic vibration generated in the plating tank in the plating solution substantially parallel to the surface to be processed of the substrate. In addition, the plating apparatus includes an ultrasonic oscillator that forms a standing wave between the wall surfaces of the plating tank, and a moving unit that moves the holding table along the surface to be processed of the substrate. 2. The plating apparatus according to claim 1, wherein the moving means rotates the holding table. 3. The plating apparatus according to claim 1, wherein the holding table is provided with heating means for heating the substrate. 4. The plating apparatus according to claim 1, further comprising a vibrating device that vertically vibrates the holding table. 5. After plating using the plating apparatus according to any one of claims 1 to 4, unnecessary portions of the metal adhering to the substrate are polished and removed by a chemical mechanical polishing apparatus. Substrate processing method.