JP2009179821A - Method and apparatus for producing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a semiconductor device, wherein the variation of the formation of a plating film on a plated semiconductor substrate is suppressed. <P>SOLUTION: Bubbles remaining on the surface of a filter (C)8 provided in an anode electrode mounted vessel 2 installed in a plating bath 1 are removed by vibrating the filter (C)8 to suppress the change of electric field largely affecting the formation of the electric field plating film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device and a manufacturing apparatus therefor, in which a wiring metal film is formed on a semiconductor substrate (hereinafter referred to as a wafer) by plating.

  In recent years, with the miniaturization of semiconductor devices, copper (Cu) has been used instead of aluminum (Al) as a wiring material. Since Cu is difficult to process by dry etching such as Al, grooves and holes are formed in the insulating film on the wafer, and a Cu barrier film and an ultra-thin film are deposited by the PVD method. A Cu film is embedded and deposited therein by electrolytic plating, and then the deposited film is polished and planarized by a CMP method (chemical mechanical polishing method) to form wiring.

  FIG. 4 is a schematic configuration diagram of a conventional typical Cu plating apparatus for electrolytically plating a wafer surface.

  In FIG. 4, a plating treatment tank 1, an anode electrode installation tank 2 installed inside the plating treatment tank 1, and a cathode that transfers current from a power source E that fixes a wafer W and supplies a constant current to the wafer W. An electrode 3, a Cu anode electrode 5 for supplying Cu ions to the plating solution 41, a pump (A) 61 for circulating the plating solution 41, a filter (A) 71 for filtering particles in the plating solution 41, A filter (C) 8 having a function as a lid for the anode electrode installation tank 2, a pump (B) 62 for circulating a plating solution 42 (plating solution containing additive) on the cathode electrode side, and particles in the plating solution 42 Filter (B) 72 for filtering, plating solution replenishing tank 9 for storing the plating solution 41 to be replenished periodically, and piping connecting the plating solution replenishing tank 9 and the anode electrode installation tank 2 0, a replenishment opening / closing valve 11 that opens and closes when replenishing and stopping the plating solution 41, a N2 gas supply pipe 12 that supplies nitrogen (N2) gas that pushes out the plating solution 41 when replenishing the plating solution 41, N2 supply opening / closing valve 13 that opens and closes when supplying and stopping the supply of N2 gas, pressure relief pipe 14 that prevents a pressure rise when replenishing plating solution 41 periodically, cathode electrode 3 and anode electrode And a voltage measuring device 15 for measuring a potential difference with respect to 5.

  Although not shown in FIG. 4, for the purpose of improving the embedding property and smoothness of the plating film, a certain amount of an organic additive is mixed in the plating solution 42, and the concentration is periodically increased. Measurements are taken and additives are replenished regularly.

  Further, in FIG. 4, a diffuser 16 and an ejection nozzle 17 for the plating solution 41 are provided to make the stirring of the additive and the circulation flow of the plating solution 42 into a laminar flow.

  Here, periodic replenishment of the plating solution will be described.

  The plating solution decreases as the number of wafers processed increases. This is because it is taken out of the plating treatment tank through the wafer. Accordingly, the plating solution is replenished to the plating tank 1 periodically (about every hour) through the anode electrode installation tank 2 and the pressure relief pipe 14 in the following procedure.

That is, when the plating replenishment time is reached, the replenishment opening / closing valve 11 and the N2 supply opening / closing valve 13 are opened. Then, N 2 gas is supplied to the plating replenishing tank 9 at a pressure of about 2 kgf / cm ² , and the replenishing plating solution is pushed. Along with this, the replenishing plating solution is inserted into the anode electrode installation tank 2 through the replenishing solution pipe 10 together with the N ₂ gas. When the replenishing plating solution is inserted into the anode electrode installation tank 2, it flows into the plating treatment tank 1 through the pressure relief pipe 14.

  The amount of plating solution to be periodically replenished is preset, and when the set amount is replenished, the N2 supply opening / closing valve 13 and the replenishing opening / closing valve 11 are closed in this order to complete a series of periodic plating replenishment operations. To do.

Next, the plating process will be described with reference to FIG. In the plating process, the wafer surface (surface to be plated) is placed and fixed on the cathode electrode 3 disposed immediately above the plating treatment tank 1, and then the wafer W is rotated together with the cathode electrode 3 to rotate the cathode. A voltage is applied between the electrode 3 and the anode electrode 5 via the power source E. In this state, the wafer W is immersed in the plating solution 42, and voltage application is stopped after a predetermined time to form a Cu plating film having a desired film thickness.
JP 2004-35973 A

  However, in the conventional plating apparatus, bubbles are mixed into the plating solution by replenishing the plating solution to be periodically replenished with N 2 gas. The mixed air bubbles adhere and stay on the surface of the filter installed in the anode electrode installation tank. Due to the retention of bubbles, the electric field generated by the voltage applied between the anode electrode and the cathode electrode changes during the plating process, and the plating film thickness changes as shown in FIG.

  As shown in FIG. 5, the variation in the thickness of the plated film varies depending on how the bubbles are attached. When the wafer W having such a changed plating formation film thickness is transported to a CMP processing apparatus in the next processing step and the wafer surface is polished, a polishing failure due to poor planarization or excessive polishing occurs, resulting in a gap between wirings. There is a problem that the yield is reduced due to connection or disconnection.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems of the prior art, and an object of the present invention is to provide a method for manufacturing a semiconductor device and a device for manufacturing the same that can suppress a change in the thickness of a plating formation on a semiconductor substrate.

  In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention includes a step of placing a semiconductor substrate on an anode electrode, and a step of immersing the anode electrode on which the semiconductor substrate is placed in a plating solution in a plating tank. And circulating the plating solution into and out of the plating bath, and applying a voltage between the anode electrode and the cathode electrode in the plating bath to plate the semiconductor substrate. In the plating process, a filter positioned between the anode electrode and the cathode electrode is vibrated.

  In addition, a semiconductor device manufacturing apparatus according to the present invention includes a plating treatment tank, a cathode electrode located in the plating treatment tank, an anode electrode located in the plating treatment tank and facing the cathode electrode, It is characterized by comprising a filter positioned between the anode electrode and the cathode electrode, a power source for applying a voltage between the anode electrode and the cathode electrode, and a vibrator for vibrating the filter.

  The method of manufacturing a semiconductor device and the manufacturing apparatus thereof according to the present invention can cause bubbles to be released and directly suppress a change in electric field by directly vibrating a filter in which bubbles adhere and stay. It is possible to suppress a change in film thickness in the formed film.

  Therefore, in the CMP processing apparatus which is the next process, a semiconductor substrate having no variation in plating film thickness between the semiconductor substrates can be transferred, the occurrence of polishing defects can be prevented, and the yield of the semiconductor device can be improved. Furthermore, equipment downtime by removing bubbles can be reduced, and productivity can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a plating apparatus according to an embodiment of the present invention. The present plating processing apparatus will be described as a plating processing apparatus for growing a copper film for wiring on the wafer surface.

  In FIG. 1, a plating treatment tank 1, an anode electrode installation tank 2 installed inside the plating treatment tank 1, and a cathode that transfers current from a power source E that fixes a wafer W and supplies a constant current to the wafer W. An electrode 3, a Cu anode electrode 5 for supplying Cu ions to the plating solution 41, a pump (A) 61 for circulating the plating solution 41, a filter (A) 71 for filtering particles in the plating solution 41, A filter (C) 8 having a function as a lid for the anode electrode installation tank 2, a pump (B) 62 for circulating a plating solution 42 (plating solution containing additive) on the cathode electrode side, and particles in the plating solution 42 Filter (B) 72 for filtering, plating solution replenishing tank 9 for storing plating solution 41 to be replenished periodically, and piping 1 connecting the plating replenishing tank 9 and the anode electrode installation tank 2 A replenishment opening / closing valve 11 that opens and closes when replenishing and stopping the plating solution 41, a N2 gas supply pipe 12 that supplies nitrogen (N2) gas that pushes out the plating solution 41 when replenishing the plating solution 41, An N2 supply opening / closing valve 13 that opens and closes when starting and stopping the supply of N2 gas, a pressure relief pipe 14 that prevents a pressure rise when replenishing the plating solution 41 periodically, a cathode electrode 3 and an anode electrode 5 And a voltage measuring device 15 for measuring the potential difference between the two.

  Although not shown in FIG. 1, for the purpose of improving the embedding property and smoothness of the plating film, a certain amount of an organic additive is mixed in the plating solution 42, and the concentration is periodically increased. Measurements are taken and additives are replenished regularly.

  Further, in FIG. 1, a diffuser 16 and an ejection nozzle 21 for the plating solution 41 are provided to make the stirring of the additive and the circulating flow of the plating solution 42 into a laminar flow.

  The present plating processing apparatus is different from the conventional one shown in FIG. 4 in that a vibrator 18 that vibrates at about 1 to 10 kHz is provided in the filter (C) 8 installed in the anode electrode installation tank 2. is there.

  Since the vibrator 18 is always immersed in the acidic plating solution 42 in this example, the vibrator 18 is covered with an acid-resistant resin (polyvinylidene fluoride) made of the same material as the plating tank 1. Further, the anode electrode installation tank 2 is easily installed in the plating treatment tank 1 through the fluororubber pedestal 19 on the bottom surface, and vibration is easily caused in other parts such as the cathode electrode 3 holding the wafer W. I try not to communicate. In this example, fluororubber is used, but it is not particular about fluororubber as long as it is acid-resistant elastic rubber. Furthermore, a vibrator operation control circuit 20 that determines the start of operation of the vibrator 18 from the measurement result from the voltage measuring device 15 is also provided.

  Next, the plating process and the operation contents of the vibrator in the plating apparatus having the above-described configuration will be described.

  First, in the plating process, the surface of the wafer W (surface to be plated) is placed and fixed on the cathode electrode 3 disposed immediately above the plating tank 1, and then the wafer W is integrated with the cathode electrode 3. Rotate and apply a voltage between the cathode electrode 3 and the anode electrode 5 via the power source E, immerse in the plating solution 42 in that state, stop the voltage application after a predetermined time, and form a Cu plating film having a desired film thickness. Form. At the time of forming the plating film, the voltage difference between the cathode electrode 3 and the anode electrode 5 is simultaneously measured by the voltage measuring device 15.

  FIG. 2 is a diagram showing a measurement result by the voltage measuring instrument in the present embodiment. When a large amount of bubbles adhere to the filter (C) 8, a potential difference of 15V is generated, which is higher than when there is no adhesion (12V). This is considered to be because bubbles become a resistance, indicating that the state between the electrodes is unstable. Along with this, the current value on the surface of the wafer W varies, and the in-plane variation of the plating film as shown in FIG. 5 occurs.

  In the case of this example, the potential difference between the cathode electrode 3 and the anode electrode 5 is 12 to 13 V in the normal state (when there is no bubble). This time, a value 1.1 times larger than the measurement result when no bubble is set is set as the operation start value, and when this value is exceeded, the vibrator operation control circuit 20 transmits a vibrator operation signal to the vibrator 18. .

  After the plating process is completed, the vibration is started at the same time as the wafer W is transferred from the cathode electrode 3 to the next process, and the vibrator 18 is vibrated at 1000 Hz until the next wafer W is placed on the cathode electrode 3. Operate. In this case, vibration is transmitted to the plating solution during the plating process, and the contact with the wafer W becomes unstable.

  In this example, the operation start value is set so that the vibrator 18 operates when the voltage meter 15 measures a potential difference greater than 13.2V. By the above operation, the bubbles generated in the plating solution and adhering to the filter 8 are removed, so that the state in the plating solution can be stabilized and the entire surface of the wafer W can be plated with a uniform film thickness.

  Further, for the purpose of further reducing the bubble accumulation and retention on the surface of the filter 8 installed in the anode electrode installation tank 2, the circulating plating solution ejection nozzle 22 in the anode electrode installation tank 2 is more filtered (C) than the conventional position. It was installed directly under 8. By applying the sprayed circulating plating solution to the filter 8 at a high flow rate, the adhesion of bubbles could be further suppressed. Note that it is desirable to install a plurality of ejection nozzles 22 in accordance with the shape of the filter (C) 8.

  By using the plating apparatus configured as described above to process the wafer, the variation was improved to 3.9% as shown in FIG. 3 (5.5% when bubbles exist).

  The present invention can suppress the formation variation of the Cu plating film thickness in the plating process for forming the metal film for wiring on the semiconductor substrate, and is particularly useful for manufacturing a miniaturized semiconductor device. Yield reduction due to the above can be suppressed.

1 is a schematic configuration diagram of a plating apparatus according to an embodiment of the present invention. The figure which shows the measurement result by the said voltage measuring device in this embodiment. The figure which shows the plating formation film thickness profile on the wafer at the time of bubble existence in this embodiment Schematic configuration diagram of conventional plating equipment The figure which shows the plating formation film thickness profile on the wafer when there is no bubble in the conventional equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating treatment tank 2 Anode electrode installation tank 3 Cathode electrode 41 Plating solution 42 Additive mixed plating solution 5 Anode electrode 61 Pump A
62 Pump B
71 Filter A
72 Filter B
8 Filter C
DESCRIPTION OF SYMBOLS 9 Plating solution replenishment tank 10 Replenisher piping 11 Replenishment opening / closing valve 12 N2 gas supply piping 13 N2 gas supply opening / closing valve 14 Pressure release piping 15 Voltage measuring device 16 Diffuser 18 Vibrator 19 Fluoro rubber base 20 Vibrator operation control circuit 21 Nozzle E Constant current power supply W Wafer

Claims (4)

A step of installing a semiconductor substrate on the anode electrode, a step of immersing the anode electrode on which the semiconductor substrate is installed in a plating solution in a plating treatment tank, a step of circulating the plating solution in and out of the plating treatment tank, Applying a voltage between the anode electrode and the cathode electrode in the plating tank and plating the semiconductor substrate,
In the step of performing the plating process, a filter positioned between the anode electrode and the cathode electrode is vibrated.   2. The method of manufacturing a semiconductor device according to claim 1, further comprising a step of measuring a potential difference between the anode electrode and the cathode electrode, and performing the vibration in the step of performing the plating process based on the potential difference.   3. The method of manufacturing a semiconductor device according to claim 1, wherein in the step of performing the plating process, the plating solution is circulated from the anode electrode in the plating tank toward the cathode electrode.   A plating treatment tank; a cathode electrode located in the plating treatment tank; an anode electrode located in the plating treatment tank opposite to the cathode electrode; and located between the anode electrode and the cathode electrode An apparatus for manufacturing a semiconductor device, comprising: a filter; a power source that applies a voltage between the anode electrode and the cathode electrode; and a vibrator that vibrates the filter.

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