KR101022028B1 - Electrochemical mechanical planarization using conductive or nonconducting polishing pad - Google Patents

Abstract

The present invention relates to an electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad, and more particularly, to an electrochemical mechanical polishing apparatus for a semiconductor wafer, comprising: a surface plate rotating by a driving force; An electrode attached to the surface plate and having a cathode applied thereto; A non-conductive polishing pad detachably coupled to the electrode and made of a non-conductive material; A polishing head disposed above the non-conductive polishing pad and fixed to a lower portion of the non-conductive polishing pad, the polishing head for rotating the wafer while pressing the non-conductive polishing pad; a connector for contacting a lower surface of the wafer to apply an anode to the wafer; A probe comprising a support that moves together along the horizontal movement of the polishing head while supporting the connector to be in contact with the surface of the wafer, and separation means for driving the support such that the connector is detachable from the surface of the wafer; Electrolyte supply means for supplying an electrolyte solution to the upper surface of the electrode; And a control unit which horizontally reciprocates the polishing head, and controls a reciprocating width of the polishing head to prevent the probe contacting the wafer from colliding with the side surface of the surface plate. Since the anode can be directly applied to the wafer through a probe to a conventional ECMP which can use only a polishing pad, a non-conductive polishing pad can also be used, and since the wafer is polished in an overhang state, uniform polishing is performed and thus the polishing efficiency is excellent.

Semiconductor, Wafer, Polishing, Pad, Planarization, Electrode, Electrolyte, Probe

Description

Electrochemical mechanical planarization using conductive or nonconducting polishing pad}

The present invention relates to an electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad. More particularly, the present invention relates to an electrochemical and mechanical polishing apparatus for planarizing a wafer during a semiconductor wafer manufacturing process. The present invention relates to an electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad that can also be used with a conductive polishing pad.

Conventionally, the chemical mechanical planarization (CMP) process, which is used for polishing a semiconductor wafer, is also referred to as a chemical mechanical planarization process, and a polishing head having a wafer attached to a polishing pad attached to a platen ( A device for chemically polishing by injecting a polishing liquid (Slurry) containing a chemical liquid that reacts with the abrasive particles (Abrasive) and the surface of the metal at the same time while the polishing head is pressurized to a constant pressure mechanically polished by mutual rotational movement I use it.

These chemical mechanical polishing devices require high polishing pressures and fast relative speeds in order to increase processing efficiency, but these mechanical factors are accompanied by the occurrence of various defects as high as the processing efficiency.

In other words, the metal wires on the wafer surface are dish-shaped due to high pressures and relative speeds, the erosions occurring in dielectric materials, and the metals are peeled off by high pressure. Delamination may occur, such as peeling. These phenomena lead to low polishing uniformity, reduced yield and lowered polishing efficiency.

Due to the problems with the CMP process, an electrochemical mechanical planarization (ECMP) process has recently emerged. The basic device is the same as that of the CMP, but the cathode is placed on the surface plate, the anode is placed on the wafer, and the conductive pad is conductive. A polishing pad is used, and an electrochemical reaction occurs between the electrode and the electrolyte while an electrolyte is injected between the wafer and the conductive polishing pad, thereby changing the metal surface of the wafer into a surface that is easily electrochemically polished. Apparatus for mechanically polishing a metal surface that has been electrochemically changed by pressing force and rotation, and has excellent characteristics of polishing efficiency even at a low polishing pressure.

Such ECMP requires fast polishing speed and polishing uniformity on the entire surface of the wafer to increase processing efficiency. Factors affecting the ECMP process include electricity supply, traces of holes in the wafer and the polishing pad, electrolytes in the electrolyte, oxidizing agents, pH regulators, complexing agents, corrosion inhibitors, and current density supplied to the wafer.

1 is a conceptual diagram showing a conventional ECMP.

As shown in the drawing, an electrode 2 to which a cathode is applied on a rotating surface plate 1, a conductive polishing pad 3 disposed on the electrode 2, and the electrode 2 and a conductive polishing pad ( 3) an insulator 4 inserted therebetween, a polishing head 5 installed and rotated above the conductive polishing pad 3, and a wafer w which is a workpiece on the polishing head 5 so as to be mounted thereon. It consists of a fixture (6) and the electrolyte supply means (7) for supplying an electrolyte solution to the conductive polishing pad (3).

At this time, the negative electrode (−) is applied to the electrode 2 and the positive electrode (+) is applied to the conductive polishing pad 3, and then the electrolyte is supplied while rotating the surface plate 1 and the polishing head 5. When the electrolyte is supplied onto the conductive polishing pad 3 through the means 7, the wafer w in contact with the conductive polishing pad 3 is applied to the positive electrode and is supplied by the electrode 2 and the negative electrode. An electrochemical change of the metal surface is carried out and mechanical polishing is performed by rotational movement.

Here, the conductive polishing pad is made of a material having a high hardness, such as a conductive metal or a conductive polymer. Therefore, a problem occurs that a fine scratch (Scratch) occurs on the wafer surface due to the conductive polishing pad during the polishing process.

Therefore, it is preferable to use a non-conductive polishing pad (material such as polyurethane) having a lower hardness than the conductive polishing pad. In this case, since the non-conductive polishing pad does not conduct electricity, there is a problem in that the wafer cannot be charged with the anode.

In this case, a separate power supply means is required to supply power to the wafer, and the wafer is a semiconductor (Si) surface of titanium (Ti), titanium nitride (TiN), tantalum (Ta), tantalum nitride (TaN). Since a conductive film such as copper is coated on the diffusion barrier such as), a power supply means must be directly connected to the conductive film in order to supply power to the conductive film. Because silicon is not conductive, it is impossible to supply current through it.

In addition, since the wafer rotates at a high speed during processing, there is a problem that power cannot be supplied by a general connection method.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to use an electrochemical mechanical wafer capable of using a non-conductive polishing pad to use a non-conductive polishing pad in an electrochemical mechanical wafer polishing apparatus using a conductive polishing pad. It is to provide a polishing apparatus.

According to an aspect of the present invention, there is provided an apparatus for electrochemically and mechanically polishing a semiconductor wafer, comprising: a surface plate rotating by a driving force; An electrode attached to the surface plate and having a cathode applied thereto; A non-conductive polishing pad detachably coupled to the electrode and made of a non-conductive material; A polishing head disposed above the non-conductive polishing pad and fixed to a lower portion of the non-conductive polishing pad, the polishing head for rotating the wafer while pressing the non-conductive polishing pad; a connector for contacting a lower surface of the wafer to apply an anode to the wafer; A probe comprising a support that moves together along the horizontal movement of the polishing head while supporting the connector to be in contact with the surface of the wafer, and separation means for driving the support such that the connector is detachable from the surface of the wafer; Electrolyte supply means for supplying an electrolyte solution to the upper surface of the electrode; And a control unit for horizontally reciprocating the polishing head, and controlling a reciprocating width of the polishing head to prevent the probe contacting the wafer from colliding with the side surface of the surface plate.

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Preferably, the support is composed of a horizontal support and a vertical support coupled to the end and the connection port is made of a conductive material and vertically coupled to the other end of the horizontal support to form a 'L' shape, the separation means is the vertical means Rotating the support is characterized in that the connector is detachable from the surface of the wafer.

Preferably, the electrode surface is characterized in that the radial discharge groove is formed so that the electrolyte is smoothly discharged.

The effect of the present invention by the configuration as described above can be applied to the anode directly through the probe to the conventional ECMP can be used only the conductive polishing pad, non-conductive polishing pad can also be used.

In addition, since the wafer is polished in an overhang state, uniform polishing is performed, and thus the polishing efficiency is excellent.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Figure 2 is a block diagram showing an electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad according to an embodiment of the present invention, Figure 3 is a plan view of one embodiment of the present invention shown in FIG.

The present invention is largely composed of the surface plate 10, the electrode 20, the non-conductive polishing pad 30, the polishing head 40, the probe 50, the electrolyte supply means 60, the control unit.

First, the surface plate 10 and the electrode 20 will be described together.

As shown in FIG. 2, the surface plate 10 has a circular cross section as a structure capable of rotating the electrode 20 and the non-conductive polishing pad 30, and rotates by a driving means such as a motor. Of course, the rotational speed of the surface plate 10 can be appropriately controlled.

In addition, the material of the surface plate 10 is a metal having a certain strength and weight is suitable, because when using a light material is a vibration occurs during the rotation at high speed can not be rotated while supporting the polishing pad stably and the wafer ( This is because an impact may be applied to w).

An electrode 20 made of a conductive material is coupled to the upper surface of the surface plate 10, and a cathode is applied to the electrode 20 by a power source. Generally used copper is suitable.

Here, the surface plate 10 and the electrode 20 should be precisely installed to keep the level exactly. This is because uneven polishing occurs when the wafer w and the horizontal plane are shifted from each other.

Next, the non-conductive polishing pad 30 will be described. The non-conductive polishing pad 30 is a polishing pad that polishes and smoothes the surface of the wafer w. The non-conductive polishing pad 30 is made of a non-conductive material that is not electrically conductive. 20) It is attached to the upper surface, but detachably attached. Desorption methods may vary, and in general, may be attached with an easy-to-remove adhesive, and when replacing with a conductive polishing pad, the attached non-conductive polishing pad 30 may be removed and a conductive polishing pad may be attached.

Preferably, since the electrolyte is supplied to the electrode 20 by the electrolyte supply means to be described later and the discharge of the used electrolyte should be easy, the non-conductive polishing pad 30 has a center penetrated as shown in FIG. 3. Donut shape is appropriate.

In general, the material of the non-conductive polishing pad 30 may be polyurethane. The non-conductive polishing pad 30 may be any kind of polishing pad having other non-conductive properties.

Next, the polishing head 40 will be described.

The polishing head 40 is disposed above the non-conductive polishing pad 30 and rotates, and a fastener 42 is provided at a lower portion thereof to fix the wafer w with the fastener 42.

The polishing head 40 is rotated by a driving means such as a servo motor capable of speed control, and is moved up and down by hydraulic pressure or pneumatic pressure, and a wafer (w) attached to the lower surface of the non-conductive polishing pad 30 is used. Pressurized to be in close contact with.

Here, the fastener 42 may have a variety of shapes, it is normal to use a retainer ring (Retainer Ring) and it is natural that a plurality of clips, such as another can be used.

For reference, the rotation speed of the polishing head 40 may be about 10rpm to 500rpm, and typically 10rpm to 100rpm is used.

Next, the probe 50 will be described. The probe 50 is configured to apply an anode to a lower surface of the wafer w fixed to the polishing head 40. ) And separation means 56.

The connection port 52 may be made of various materials such as a ball shape or a rectangular parallelepiped shape with a conductive material in contact with the surface of the wafer w, and a material having a low hardness may be appropriately used.

The support 54 supports the connector 52 to maintain the contact state with the lower surface of the wafer w. The support 54 includes a horizontal support 54a and a vertical support 54b. The bar has a bar shape made of a conductive material and is disposed horizontally so that the connection port 52 is coupled to an end thereof, and a wire is connected to the other end to supply power.

In addition, it is preferable that the vertical support 54b is vertically coupled to the other end of the horizontal support 54a so that the support 54 has an L-shape as a whole, and the vertical support 54b has a rod shape. This is because the separating means 56 is interlocked on the top of the vertical support 54b so that the vertical support 54b is rotated like an axis by the separating means 56.

Due to this configuration, when the vertical support 54b rotates at a predetermined angle, the horizontal support 54a rotates. As a result, the connection port 52 may be detached from the surface of the wafer w to block the supply of power.

Therefore, it is apparent that the separating means 56 is appropriately the same as a motor capable of rotating the vertical support 54b, and may be configured manually by being provided with a handle capable of rotating the vertical support 54b. .

In this case, since the polishing head 40 is movable left and right, the probe 50 should also move together so that the probe 50 continuously supplies power. Therefore, the probe 50 should be coupled to the polishing head 40 at a predetermined interval.

In addition, it is preferable that a plurality of probes 50 be provided as shown in FIG. 3 because it can supply power to the wafer w uniformly and stably.

Next, the electrolyte supply means 60 disposed above the nonconductive polishing pad 30 and supplying the electrolyte solution to the electrode 20 will be described.

The electrolyte may generally include a sulfuric acid electrolyte, a phosphoric acid electrolyte or a combination thereof. The electrolyte supply means 60 may be configured to store the electrolyte in a separate tank and to be connected through a hose and sprayed through a nozzle, but is not limited thereto.

For reference, the discharge groove 22 is preferably formed on the surface of the electrode 20 so that the electrolyte flows smoothly to the outside, the discharge groove 22 is a plurality of concentric circles as shown in FIG. Although a plurality may be formed radially about the center, the shape of the discharge groove 22 may vary.

Next, the control unit (not shown) controls the rotation speed of the surface plate 10 and the polishing head 40 while oscillating the polishing head 40 to the left and right at a predetermined interval as a general control configuration. do.

As the polishing head 40 reciprocates during wafer w polishing, a uniform polishing effect can be obtained on the surface of the wafer w, and uniform consumption of the polishing pad can be achieved.

At this time, the reciprocating width of the polishing head 40 is controlled to be limited, which means that the connection port of the probe 50 in contact with the wafer w is the non-conductive polishing pad 30, the electrode 20, or the like. Do not collide with the surface plate 10.

In this state, when the polishing process is performed, the wafer w is polished in the overhang of the non-conductive polishing pad 30, so that the edge of the wafer w has a relatively short polishing distance, thereby improving polishing uniformity.

Since the mechanical mechanism for causing the polishing head 40 to reciprocate is well known, a detailed description thereof will be omitted.

Hereinafter, a wafer polishing process using the present invention will be described.

First, the non-conductive polishing pad 30 is attached to the upper surface of the electrode 20 with an adhesive, and the wafer w to be processed is bitten and fixed to the fixture 42 on the polishing head 40.

The vertical support 54b is rotated so that the connector 52 is in contact with the surface of the wafer w, and a negative electrode is supplied to the electrode 20 and a positive electrode is supplied to the connector 52.

Then, the polishing head 40 is lowered to be in close contact with the non-conductive polishing pad 30, and then the surface plate 10 and the polishing head 40 are rotated at an appropriately set rotational speed. A wafer (w) is polished by supplying an electrolyte solution to the electrode 20 through the?

At this time, the polishing head 40 is reciprocated to a predetermined width through the control unit to improve the polishing efficiency. In addition, a portion of the wafer w is separated from one side of the non-conductive polishing pad 30 so that the connector 52 does not collide with the non-conductive polishing pad 30 or the side of the electrode 20. Polishing process is performed in the state.

If the conductive polishing pad 70 is to be used, as shown in FIG. 4, the non-conductive polishing pad 30 is removed from the electrode 20, and the conductive plate 72 and the plate 72 to which an anode is applied. ) After attaching a conductive polishing pad 70 composed of an insulator 74 attached to the lower portion to the electrode 20, the probe 50 is separated from the wafer w, and then an anode is formed on the conductive polishing pad 70. Is applied to carry out the polishing process.

1 is a block diagram showing an electrochemical mechanical wafer polishing apparatus using a conventional conductive polishing pad.

Figure 2 is a block diagram showing an electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad according to an embodiment of the present invention.

3 is a plan view of one embodiment of the illustrated invention of FIG.

Figure 4 is a block diagram showing a state using a conductive polishing pad in the present invention.

<< Explanation of main parts of drawing >>

10: plate 20: electrode

22: discharge groove 30: non-conductive polishing pad

40: polishing head 42: fixture

50: probe 52: connection port

54: support 54a: horizontal support

54b: vertical support 56: separation means

60: electrolyte supply means 70: conductive polishing pad

72: plate 74: insulator

w: wafer

Claims (4)

delete An apparatus for electrochemically and mechanically polishing a semiconductor wafer (w), A surface plate 10 rotated by a driving force; An electrode 20 attached to the surface plate 10 and having a cathode applied thereto; A non-conductive polishing pad 30 detachably coupled to the electrode 20 and made of a non-conductive material; A polishing head 40 disposed above the nonconductive polishing pad 30 and provided with a fixture 42 for fixing the wafer w at the bottom thereof to rotate the wafer w while pressing the wafer w against the nonconductive polishing pad 30. ); A splice 52 for contacting the lower surface of the wafer w to apply an anode to the wafer W, and a horizontal of the polishing head 40 while supporting the splice 52 so as to contact the surface of the wafer w. A probe (50) consisting of a support (54) moving together with movement and the separating means (56) for driving the support (54) so that the connector (52) is detachable from the surface of the wafer (w); Electrolyte supply means (60) for supplying an electrolyte solution to the upper surface of the electrode (20); And The polishing head 40 is horizontally reciprocated, and the width of the reciprocating movement of the polishing head 40 is prevented to prevent the probe 50 contacting the wafer w from colliding with the side surface of the surface plate 10. An electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad, characterized in that consisting of a control unit for controlling. The method of claim 2, The support 54, The connector 52 is coupled to an end thereof and includes a horizontal support 54a made of a conductive material, and a vertical support 54b vertically coupled to the other end of the horizontal support 54a to form an 'L' shape. An electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad, characterized in that the separating means 56 rotates the vertical support 54b so that the connector 52 can be separated from the surface of the wafer w. . The method according to any one of claims 2 to 3, Electrochemical mechanical wafer polishing apparatus capable of using a non-conductive polishing pad, characterized in that the radial discharge groove 22 is formed on the surface of the electrode 20 to smoothly discharge the electrolyte.

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