JP2008060453A - Semiconductor manufacturing apparatus, and manufacturing method for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate electric charges from the surface of a semiconductor wafer to suppress the production of foreign matter, such as slurry abrasive grains sticking to a plug. <P>SOLUTION: A semiconductor manufacturing apparatus for carrying out a CMP treatment on a semiconductor wafer 1 is composed of a plurality of units. The semiconductor manufacturing apparatus has a charge neutralizer 9 which is disposed on a unit 7 that is one of the plurality of units, and eliminates electric charges from the surface of the semiconductor wafer 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a CMP apparatus used in a planarization process such as chemical mechanical polishing (CMP) performed in the manufacture of a semiconductor wafer, and more particularly to neutralize the charge on the surface of the semiconductor wafer generated during CMP, thereby removing the surface of the semiconductor wafer. The present invention relates to a CMP apparatus for reducing foreign matter adhering to a semiconductor device and a method of manufacturing a semiconductor device using the apparatus.

  In general, a CMP apparatus is used when processing the surface of a flat workpiece such as a semiconductor wafer flat.

At present, a CMP apparatus in which a series of processes of chemical mechanical polishing, cleaning, and drying is performed in the same apparatus has become mainstream. A CMP apparatus generally includes a unit for mounting or removing a semiconductor wafer, a polishing unit for polishing a semiconductor wafer, a cleaning unit for cleaning the polished wafer, a drying unit for drying the cleaned wafer, and a head used for polishing. A plurality of units such as a head cleaning unit for cleaning are provided. In such a CMP apparatus, after the semiconductor wafer is chemically mechanically polished by the polishing unit, the semiconductor wafer transferred to the cleaning unit is cleaned, and then the semiconductor wafer transferred to the drying unit is dried. Is carried out from the CMP apparatus.
JP 2005-72559 A

  By the way, in the CMP apparatus, in the step of polishing while rubbing the surface of the semiconductor wafer, charging (charge up) occurs on the surface of the semiconductor wafer that is the workpiece, and the charge is dielectrically formed. In particular, in a process of forming a tungsten plug using CMP, charge is transferred to and accumulated in the plug formed by CMP. As a result, foreign substances such as slurry abrasive grains are selectively electrostatically adsorbed and aggregated on the plug.

In this regard, plugs in recent multilayer devices tend to be longer than conventional plugs, so that the capacity for accumulating charges has increased. The amount of charge accumulation depends on the plug length, aspect ratio, and plug volume, and residual foreign matter appears on the plug at a plug length of 500 nm or more, an aspect ratio of 5 or more, or a plug volume of 4.0 × 10 ⁶ nm ³ . Has been confirmed. In the case of a stacked contact plug structure in an embedded DRAM in a recent multilayer device, the plug length is about 900 nm, and this phenomenon appears remarkably.

  As described above, foreign matters such as slurry abrasive grains remaining on the plug cause an open defect between the wiring of the device and the plug, and as a result, the yield of the semiconductor wafer is reduced. In addition, with the recent trend toward ultra-miniaturization of LSIs, the open defect problem caused by the residual foreign matter on the plug, which has been allowed in the past, cannot be ignored.

  For such problems, for the purpose of removing foreign matters such as slurry abrasive grains remaining on the plug, there has been proposed a method of strengthening cleaning after CMP, for example, performing an additional cleaning process. The enhancement of cleaning in the process is due to the complexity of the cleaning process, the increase in the amount of chemicals used, and the lengthening of the cleaning process, thereby increasing the cost of ownership (CoO) and reducing the production capacity of semiconductor manufacturing equipment. It was.

  In view of the above, an object of the present invention is to remove a charge on the surface of a semiconductor wafer and suppress generation of foreign matter such as slurry abrasive grains adsorbed on a plug, for example, and manufacture of a semiconductor device using the device Is to provide a method.

  In order to achieve the above object, a semiconductor manufacturing apparatus according to one aspect of the present invention is a semiconductor manufacturing apparatus for CMP processing of a semiconductor wafer composed of a plurality of units. A neutralization unit is provided in the unit and neutralizes the charge on the surface of the semiconductor wafer.

  According to the semiconductor manufacturing apparatus according to one aspect of the present invention, the charge on the surface of the semiconductor wafer is removed, for example, the generation of foreign matters such as slurry abrasive grains adsorbed on the plug is suppressed, and the semiconductor wafer including the plug adheres to the semiconductor wafer. It is possible to easily remove foreign matters such as slurry abrasive grains. For this reason, for example, an open defect problem caused by residual foreign matter can be solved, and a semiconductor manufacturing apparatus that is excellent in apparatus production capability and wafer yield and can reduce CoO can be realized.

  In the semiconductor manufacturing apparatus according to one aspect of the present invention, it is preferable that the semiconductor manufacturing apparatus further includes a surface potential measuring unit that is provided in one unit and measures the surface potential of the semiconductor wafer.

  In this way, since the adhesion of foreign matter due to charging can be quantitatively evaluated, it is possible to provide feedback to the semiconductor manufacturing process by performing preliminary evaluation on the problem due to charging.

  In the semiconductor manufacturing apparatus according to one aspect of the present invention, it is preferable that the one unit is a wafer load / unload unit, a wafer load unit, a wafer unload unit, a polishing head cleaning unit, or a wafer polishing unit. Also, when providing a static eliminating unit or a surface potential measuring unit in the wafer polishing unit, operate the polishing head so that it protrudes from the surface plate constituting the wafer polishing unit or from the surface plate constituting the wafer polishing unit. It is preferable to be provided below the region that protrudes or below the region where the polishing head moves between the surface plates constituting the wafer polishing unit.

  A manufacturing method of a semiconductor manufacturing apparatus according to an aspect of the present invention is a manufacturing method of a semiconductor device for manufacturing a semiconductor device by polishing a semiconductor wafer using CMP, the step (a) of polishing a semiconductor wafer, After the step (a), the method includes a step (b) of cleaning the semiconductor wafer, and the step (a) or (b) includes a step of neutralizing the charge on the surface of the semiconductor wafer.

  According to the method of manufacturing a semiconductor manufacturing apparatus according to one aspect of the present invention, the semiconductor wafer including the plug is removed while charging on the surface of the semiconductor wafer is removed to suppress generation of foreign matters such as slurry abrasive grains adsorbed on the plug. It is possible to easily remove foreign matters such as slurry abrasive grains adhering to the top.

  According to the present invention, by removing the charge on the surface of the semiconductor wafer, for example, an open defect problem caused by residual foreign matter is solved, and a semiconductor manufacturing apparatus capable of reducing CoO with excellent apparatus production capacity and wafer yield is realized. The

  First, a general schematic configuration and operation of the CMP apparatus will be described below.

  The CMP apparatus generally includes a wafer load unit for mounting a semiconductor wafer, a wafer unload unit for removing and removing a semiconductor wafer (hereinafter referred to as a wafer L / UL), and a polishing unit for polishing a semiconductor wafer (hereinafter referred to as a wafer polishing unit). A plurality of units such as a unit for cleaning the polished wafer, a drying unit for drying the cleaned wafer, and a unit for cleaning the polishing head used for polishing (hereinafter referred to as a polishing head cleaning unit) are provided in the transport path of the semiconductor wafer. Is provided. Note that, depending on the CMP apparatus, the wafer L / UL and the head cleaning unit may be independent from each other or may be integrated, and any form may be used in the present invention. Also, the wafer L / UL includes a wafer loading unit and a wafer unloading unit that are independent from each other or an integrated type, and may be in any form in the present invention.

  FIG. 1A shows a general configuration of a wafer polishing unit in a CMP apparatus. The wafer polishing unit includes a surface plate (platen) 2 and a polishing cloth (polishing pad) attached to the upper surface of the surface plate. 3), a polishing head 4, a wafer holding pad 5 for holding the semiconductor wafer 1, a slurry supply nozzle 6, a retainer ring (guide ring) 8, and the like. FIG. 1B shows a general configuration of the wafer L / UL and the head cleaning unit 7 in which the wafer L / UL and the head cleaning unit in the CMP apparatus are integrally formed. Indicates a state in which the polishing head 4 has moved.

  The polishing head 4 that holds the semiconductor wafer 1 can move between the units. In the wafer polishing section, the polishing head 4 that holds the semiconductor wafer 1 that is the material to be polished on the lower surface faces the surface plate 2. And it is arranged above it. In a state where the surface plate 2 is rotated, the slurry is supplied from the slurry (abrasive) supply nozzle 6 onto the polishing cloth 3 and the polishing head 4 is pressed against the polishing cloth 3. Is polished. The retainer ring 8 is attached to the polishing head 4 and has a function of fixing and holding the semiconductor wafer 1 in the polishing head 4 without popping out during polishing of the semiconductor wafer 1. The retainer ring 8 is made of Teflon. And engineering plastics such as PPS are used. Further, the semiconductor wafer 1 may be polished while the retainer ring 8 is pressed against the polishing pad 3 during polishing of the semiconductor wafer 1.

  During polishing of the semiconductor wafer 1, the polishing is performed while the wafer holding pad (wafer contact surface) 5 of the polishing head 4 that holds the semiconductor wafer 1 is in contact with the back surface of the semiconductor wafer 1. The material may be a hard material or a soft material. As the hard material, SUS material, alumina ceramics, or the like is used, and the surface of the semiconductor wafer 1 is polished with the back surface of the semiconductor wafer 1 held directly by vacuum suction or the like, which is called a top ring or the like. On the other hand, as the soft material, an elastic film using a silicon rubber film and a neoprene rubber film, which is used as an air back type polishing head and called a membrane, is used, and the back surface of the semiconductor wafer 1 is held. When polishing the surface of the semiconductor wafer 1 or using a so-called backing pad or the like obtained by vapor-depositing rubber on a plastic thin film, the back surface of the semiconductor wafer 1 is held by water-filled adsorption or vacuum adsorption. The surface of the semiconductor wafer 1 is polished.

  On the other hand, in the wafer L / UL and the head cleaning unit 7, the cleaning is performed in the head cleaning unit when the polishing head 4 is in the wafer non-holding state. Further, the semiconductor wafer 1 as the material to be polished is attached to and detached from the polishing head 4 by the wafer L / UL.

  Here, a semiconductor manufacturing apparatus according to an embodiment of the present invention is a semiconductor manufacturing apparatus having the above-described general configuration, in which a static elimination unit that neutralizes the surface of the semiconductor wafer 1 and a surface potential of the semiconductor wafer 1 are set. And a surface potential measuring unit for measurement. As a result, the charge on the surface of the semiconductor wafer 1 is removed to suppress the generation of foreign matter such as slurry abrasive grains adsorbed on the plug, and the foreign matter such as slurry abrasive grains adhering to the plug by removing the charge. The electrostatic attractive force between the semiconductor wafer 1 including the plug and the semiconductor wafer 1 including the plug can be invalidated, and foreign substances such as slurry abrasive grains adhering to the semiconductor wafer 1 including the plug can be easily removed. As a result, for example, an open defect problem caused by residual foreign matter is solved, and a semiconductor manufacturing apparatus that is excellent in apparatus production capacity and wafer yield and can reduce CoO is realized.

  Specifically, what is generally called an ionizer is used as the static elimination unit. By using an ionizer, for example, an equal amount of plus / minus air ions are generated, and the charged substance on the semiconductor wafer 1 comes into contact with ions of the opposite polarity, thereby reducing the charged potential and the same amount of plus / minus ions. The electric field is balanced at a low potential so that negative ions come into contact with the charged object. When using, for example, a soft X-ray irradiation mechanism as the ionizer, the surface of the semiconductor wafer 1 is ionized and the static electricity is removed by irradiating the surface of the wafer 1 with a weak X-ray of 3 to 9 KeV. I do. In this way, by effectively removing the charge on the surface of the semiconductor wafer 1, it is possible to reduce the burden of the cleaning process after CMP, and to reduce the CoO without reducing the apparatus production capacity and the wafer yield. A CMP apparatus that can be reduced and a method for manufacturing a semiconductor device using the apparatus can be provided.

  Further, a non-contact surface potential sensor is used as the surface potential measuring unit. By measuring the potential of the surface of the semiconductor wafer 1, it is possible to quantitatively evaluate the adhesion of foreign matter due to charging, so that it is possible to provide feedback to the semiconductor manufacturing process by conducting a prior evaluation on problems due to charging. It becomes possible.

  Hereinafter, a semiconductor manufacturing apparatus according to the present invention that realizes the above-described effects and a method of manufacturing a semiconductor device using the apparatus will be described in each embodiment according to the installation positions of the surface potential measurement unit and the charge removal unit. To do.

(First embodiment)
In the first embodiment of the present invention, as shown in FIG. 2, the above-described surface potential measurement unit is added to the wafer L / UL and the head cleaning unit 7 in which the wafer L / UL and the head cleaning unit are integrally formed. A CMP apparatus in which the charge removal unit 9 is provided will be described.

-When a surface potential measurement unit and static elimination unit are provided in the wafer load unit-
After the semiconductor wafer 1 is mounted on the polishing head 4 by the wafer load unit, the polishing head 4 is lowered or the wafer load unit is raised so that the lower surface of the polishing head 4 is covered by the wafer load unit. Next, the surface potential of the semiconductor wafer 1 is measured by the non-contact surface potential sensor in the surface potential measurement unit and the charge removal unit 9 provided in the wafer load unit immediately below the polishing head 4 while rotating the polishing head 4. Note that the rotation speed and measurement time of the polishing head 4 can be arbitrarily set in the same manner as the polishing recipe of the CMP apparatus. After measuring the surface potential of the semiconductor wafer 1, the polishing head 4 is raised or the wafer load unit is lowered to place the polishing head 4 in a standby state. Through the above steps, the surface potential of the semiconductor wafer 1 before polishing is measured. The measured surface potential of the semiconductor wafer 1 before polishing can be used as reference data.

-When a surface potential measurement unit and static elimination unit are provided in the wafer unload unit-
Before the semiconductor wafer 1 is detached from the polishing head 4 by the wafer unload unit, the polishing head 4 is lowered or the wafer unload unit is raised so that the lower surface of the polishing head 4 is covered by the wafer unload unit. . Next, the surface potential measuring unit provided in the wafer unloading unit directly under the polishing head 4 while rotating the polishing head 4, the non-contact surface potential sensor in the neutralization unit 9, and the ionizer of the soft X-ray irradiation type mechanism, the semiconductor Electric potential measurement on the surface of the wafer 1 and charge removal on the surface of the semiconductor wafer 1 are performed. Note that the rotation speed and measurement time of the polishing head 4 can be arbitrarily set in the same manner as the polishing recipe of the CMP apparatus. After the surface potential measurement and charge removal, the polishing head 4 is raised or the wafer unload unit is lowered to place the polishing head 4 in a standby state. Through the above steps, surface potential measurement and static elimination of the semiconductor wafer 1 after polishing are performed.

-When a surface potential measurement unit and static elimination unit are provided in the head cleaning unit-
With the semiconductor wafer 1 before and after polishing mounted on the polishing head 4 by the head cleaning unit, the polishing head 4 is lowered or the head cleaning unit is raised so that the head cleaning unit covers the lower surface of the polishing head 4. Next, while rotating the polishing head 4, the surface potential measuring unit provided in the head cleaning unit immediately below the polishing head 4, the non-contact surface potential sensor in the static eliminating unit 9, and the ionizer of the soft X-ray irradiation mechanism, Conduct surface potential measurement and charge removal. Note that the rotation speed and measurement time of the polishing head 4 can be arbitrarily set in the same manner as the polishing recipe of the CMP apparatus. After the surface potential measurement and static elimination, the polishing head 4 is raised or the head cleaning unit is lowered to place the polishing head 4 in a standby state. Through the above steps, measurement of the surface potential of the semiconductor wafer 1 before and after polishing and static elimination are performed.

(Second Embodiment)
In the second embodiment of the present invention, as shown in FIG. 3, a CMP apparatus in the case where the above-described surface potential measuring unit and static eliminating unit 9 are provided in a wafer polishing unit will be described.

-When a surface potential measurement unit and a charge removal unit are provided on the side of the surface plate 2 in the wafer polishing unit-
As shown in FIG. 3, the surface potential measuring unit and the charge eliminating unit described above are provided at a side position of the surface plate 2 of the wafer polishing unit in the CMP apparatus (below the swinging operation region during polishing of the polishing head 4). It has been.

  During polishing of the wafer 1 mounted on the polishing head 4 on the surface plate 2, the polishing head 4 is swung out so that the polishing head 4 protrudes outward from the outer edge portion of the surface plate 2. In this state, the surface potential measurement and the charge removal of the semiconductor wafer 1 are performed by the surface potential measurement unit and the charge removal unit provided below the region where the polishing head 4 protrudes. Timings such as the measurement of the surface potential of the semiconductor wafer 1 and the start or end of charge removal, and the sampling period can be arbitrarily set as in the polishing recipe of the CMP apparatus. In this case, the surface potential of the semiconductor wafer 1 and the charge removal can be performed separately from the polishing (Ex-Site) or simultaneously with the polishing (In-Site). For example, it is possible to carry out a process such as performing static elimination during the rinse cleaning process using DIW or the like after the polishing using the slurry is completed, or performing the rinse cleaning process after performing static elimination during the polishing using the slurry. Is possible.

  Although not shown, it is also possible to provide the above-described surface potential measurement unit and charge removal unit below the wafer transfer operation area of the polishing head 4 between the surface plates 2. In this case, at the timing when the polishing head 4 holding the semiconductor wafer 1 is transported between the surface plates 2, the surface potential of the semiconductor wafer 1 may be measured and neutralized.

-When a surface potential measurement unit and a static elimination unit are incorporated in the surface plate 2 of the wafer polishing unit-
As shown in FIG. 4, the above-described surface potential measuring unit and charge eliminating unit are provided in the surface plate 2 of the wafer polishing unit in the CMP apparatus. In this case, a sensor window 10 is provided in a part of the polishing cloth 3 attached on the surface plate 2 so that X-rays and the like can be transmitted.

  Timings such as the measurement of the surface potential of the semiconductor wafer 1 and the start or end of charge removal, and the sampling period can be arbitrarily set as in the polishing recipe of the CMP apparatus. In this case, the surface potential of the semiconductor wafer 1 and the charge removal can be performed separately from the polishing (Ex-Site) or simultaneously with the polishing (In-Site). For example, it is possible to carry out a process such as performing static elimination during the rinse cleaning process using DIW or the like after the polishing using the slurry is completed, or performing the rinse cleaning process after performing static elimination during the polishing using the slurry. Is possible.

  In each of the above embodiments, the case where the static elimination unit and the surface potential measurement unit are provided in the existing unit constituting the CMP apparatus such as the wafer L / UL, the wafer polishing unit, or the head cleaning unit has been described. However, the present invention is not limited thereto, and for example, a configuration in which a charge removal unit and a surface potential measurement unit are provided in a unit independent of an existing unit in a wafer transfer path in a CMP apparatus may be employed.

  The present invention is useful for a CMP apparatus that performs a polishing process for charging a surface of a semiconductor wafer and a polishing process using the apparatus.

(A) And (b) is sectional drawing which shows the general schematic structure of CMP apparatus. It is sectional drawing which shows the structure of the semiconductor manufacturing apparatus provided with the surface potential measurement part and static elimination part which concern on the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor manufacturing apparatus provided with the surface potential measurement part and static elimination part which concern on the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the semiconductor manufacturing apparatus provided with the surface potential measurement part and static elimination part which concern on the 2nd Embodiment of this invention.

Explanation of symbols

1 Semiconductor wafer (material to be polished)
2 Platen (platen)
3 polishing cloth (polishing pad)
4 Polishing head 5 Wafer holding pad (Wafer contact surface)
6 Slurry supply nozzle 7 Wafer L / UL and polishing head cleaning unit 8 Retainer ring (guide ring)
9 Surface potential measurement unit and neutralization unit 10 Sensor window

Claims (10)

A semiconductor manufacturing apparatus for CMP processing of a semiconductor wafer, comprising a plurality of units,
A semiconductor manufacturing apparatus, comprising: a static elimination unit that is provided in one of the plurality of units and neutralizes the charge on the surface of the semiconductor wafer.   The semiconductor manufacturing apparatus according to claim 1, further comprising a surface potential measuring unit provided in the one unit and measuring a surface potential of the semiconductor wafer.   2. The wafer loading / unloading unit according to claim 1, wherein the one unit is a wafer loading / unloading unit that attaches the semiconductor wafer to a polishing head before polishing and detaches the semiconductor wafer from the polishing head after polishing. Semiconductor manufacturing equipment.   2. The semiconductor manufacturing apparatus according to claim 1, wherein the one unit is a wafer load unit for mounting the semiconductor wafer on a polishing head before polishing.   2. The semiconductor manufacturing apparatus according to claim 1, wherein the one unit is a wafer unload unit that removes the semiconductor wafer from a polishing head after polishing. 3.   The semiconductor manufacturing apparatus according to claim 1, wherein the one unit is a polishing head cleaning unit that cleans the polishing head. The one unit is a wafer polishing unit for polishing the semiconductor wafer,
The static eliminator is within a surface plate constituting the wafer polishing unit, or below a region protruding from the surface plate by operating a polishing head so as to protrude from the surface plate constituting the wafer polishing unit, or the wafer polishing unit. The semiconductor manufacturing apparatus according to claim 1, wherein the semiconductor manufacturing apparatus is provided below a region in which the polishing head moves between the surface plates constituting the plate. The one unit is a wafer polishing unit for polishing the semiconductor wafer,
The surface potential measuring unit is in a surface plate constituting the wafer polishing unit, or below a region protruding from the surface plate by operating a polishing head so as to protrude from the surface plate constituting the wafer polishing unit, or the wafer The semiconductor manufacturing apparatus according to claim 2, wherein the semiconductor manufacturing apparatus is provided below a region where the polishing head moves between the respective surface plates constituting the polishing unit. A semiconductor device manufacturing method for manufacturing a semiconductor device by polishing a semiconductor wafer using CMP,
Polishing the semiconductor wafer (a);
A step (b) of cleaning the semiconductor wafer after the step (a);
The step (b) includes a step of neutralizing the charge on the surface of the semiconductor wafer. A semiconductor device manufacturing method for manufacturing a semiconductor device by polishing a semiconductor wafer using CMP,
Polishing the semiconductor wafer (a);
A step (b) of cleaning the semiconductor wafer after the step (a);
The method (a) includes a step of neutralizing the charge on the surface of the semiconductor wafer.

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