JP2006231419A - Polishing device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polishing device and method for mitigating a drying environment around a wafer carrier. <P>SOLUTION: This polishing device polishes a wafer held by the wafer carrier by making the wafer abut on a rotating polishing pad, while supplying slurry. The polishing device is provided with a humidifying means 70 for controlling the internal humidity to a prescribed value. The polishing is performed, while maintaining the inside of the polishing device at the prescribed humidity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing apparatus and a polishing method, and more particularly to a wafer polishing apparatus and a polishing method by chemical mechanical polishing (CMP).

  In recent years, with the development of semiconductor technology, design rules have been miniaturized and multilayered wiring has been progressed, and the wafer diameter has been increased in order to reduce costs. Therefore, when trying to form the pattern of the next layer as it is on the layer where the pattern is formed as in the past, it is difficult to form a good pattern in the next layer due to the unevenness of the previous layer, It was easy to occur.

  Therefore, the surface of the layer on which the pattern is formed is flattened, and then the pattern of the next layer is formed. In this case, a wafer polishing apparatus using a CMP method is used.

  As a wafer polishing apparatus by this CMP method, a disk-shaped polishing surface plate having a polishing pad affixed to the surface, and a wafer carrier that holds one surface of the wafer and makes the other surface of the wafer contact the polishing pad A CMP apparatus that polishes the other surface of the wafer while rotating the polishing platen and bringing the wafer into contact with the polishing pad while rotating the wafer carrier and supplying a slurry as an abrasive between the polishing pad and the wafer. Generally known widely.

  The wafer carrier for holding the wafer has a back plate that has an air outlet on the lower surface and applies a pressing force to the wafer via a pressure air layer formed by air supplied from the air outlet, and the radial direction of the wafer And a retainer ring that presses the polishing pad and a suction port for wafer suction, and contacts the wafer to transmit the pressing force applied from the back plate through the pressure air layer to the wafer. And a protective sheet that prevents the back surface of the wafer from directly contacting the hard surface of the back plate and being damaged (see, for example, Patent Document 1).

  In this wafer carrier, the pressing force applied to the back plate is transmitted to the wafer via the pressure air layer and the protective sheet by the pressure of the air jetted from the back plate, and the wafer is pressed against the polishing pad. Therefore, the protective sheet needs to press the wafer uniformly, and is formed of a material that has a property of being easily stretched while being difficult to stretch.

The protective sheet has a suction port for wafer suction, and is used to suck and hold the wafer when the wafer is transported. When transporting the wafer, first, the wafer is relatively positioned in the retainer ring of the wafer carrier, and air is sucked from the air suction port of the back plate so that the inside of the protective sheet is decompressed. The wafer is brought into close contact with the surface of the protective sheet by the reduced pressure atmosphere inside the protective sheet and is conveyed in this state. The wafer transported to the upper surface of the polishing pad is released from the air suction, and the air suction port of the back plate is now changed to the air injection port, and the wafer is pressed against the polishing pad by receiving a pressing force through the protective sheet. Polishing is started.
JP 2000-317819 A

  However, in this conventional polishing apparatus, the air injected from the back plate for forming the pressure air layer is dry air, and the pressure air layer is configured to serve as a static pressure air bearing. The same amount of air as the supplied air is constantly discharged.

  For this reason, the discharged dry air dries the inside of the polishing apparatus, particularly the polishing portion. In such a dry environment, the slurry scattered on the wafer carrier or the wafer may be dried and aggregated to become foreign matter.

  Further, at the time of polishing a normal wafer, since the wafer is pressed against the rotating polishing pad, it receives a large frictional force in the rotating direction of the polishing pad. In this state, if foreign matter is mixed between the wafer and the protective sheet, a problem occurs.

  Normally, the surface of the protective sheet is sufficiently cleaned every time in the polishing sequence, and no foreign matter is mixed between the wafer and the protective sheet. However, when the apparatus is stopped for a short time due to some trouble, in some cases, the slurry scattered on the surface of the protective sheet is dried as it is and becomes a foreign substance in the above-mentioned drying environment. In this way, when some bad condition overlaps and foreign matter is caught between the wafer and the protective sheet, the adhesion between the wafer and the protective sheet is deteriorated, the wafer and the protective sheet are easily rubbed, and the foreign matter is caught. By rubbing in the state, the back surface of the wafer may be damaged.

  Further, when the wafer and the protective sheet are rubbed, a part of the surface of the protective sheet may be melted and welded to the back surface of the wafer.

  In addition, if a minute foreign matter enters between the wafer and the protective sheet, the adhesion between the wafer and the protective sheet will deteriorate, so that the air sprayed from the back plate will leak from the protective sheet suction port during polishing. In some cases, the wafer passes through a minute gap formed between the wafer and the protective sheet. The leaked air accelerates the drying of the slurry that touches the outer peripheral portion of the wafer back surface, and causes the problem that the slurry adheres and aggregates in the vicinity of the outer peripheral portion of the wafer back surface.

  The present invention has been made in view of such circumstances, and alleviates the dry environment around the wafer carrier, and when some adverse conditions overlap and foreign matter enters between the wafer and the protective sheet, the wafer is rubbed with foreign matter. Therefore, an object of the present invention is to provide a polishing apparatus and a polishing method for a wafer which do not cause scratches on the back surface of the wafer or cause a part of the protective sheet to be welded to the back surface of the wafer.

  In addition, when the wafer is polished, the adhesion between the wafer and the protective sheet deteriorates, and air that presses the wafer leaks out from the suction port of the wafer provided on the protective sheet, and slurry is formed near the outer periphery of the back surface of the wafer. It is an object of the present invention to provide a wafer polishing apparatus and a polishing method that do not adhere and agglomerate.

  In order to achieve the above object, the present invention provides a polishing apparatus that polishes a wafer held by a wafer carrier in contact with a rotating polishing pad while supplying a slurry. In the polishing method for polishing the wafer using the polishing apparatus, polishing is performed while controlling the humidity inside the polishing apparatus to a predetermined value. It is characterized by.

  According to the present invention, since the inside of the polishing apparatus is controlled to a predetermined humidity, adhesion and aggregation of slurry and the like inside the polishing apparatus is reduced. Further, drying in the wafer polishing section and the conveyance path is also prevented.

  Further, the present invention provides a polishing apparatus having a polishing unit that polishes a wafer held by a wafer carrier in contact with a rotating polishing pad while supplying slurry, and sets the humidity inside the polishing unit to a predetermined value. In the polishing method for polishing the wafer using a polishing apparatus having the polishing unit, polishing is performed while controlling the humidity inside the polishing unit to a predetermined value. It is characterized by doing.

  According to the present invention, since the inside of the polishing unit of the polishing apparatus is controlled to a predetermined humidity, the inside of the polishing unit of the polishing apparatus is prevented from being dried, and the adhesion and aggregation of slurry and the like are alleviated.

  Further, the present invention provides a polishing apparatus for polishing a wafer held by a wafer carrier by contacting the rotating polishing pad while supplying slurry, and the wafer carrier has an air outlet on the lower surface thereof. A back plate for applying a pressing force to the wafer via a pressure air layer formed by air supplied from the jet port, a retainer ring for restricting movement of the wafer in the radial direction and pressing the polishing pad, and A protective sheet that contacts and transmits a pressing force applied from the back plate through the pressure air layer to the wafer, and controls the humidity of the air supplied from the air outlet to a predetermined value. A polishing method for polishing the wafer using a polishing apparatus having the wafer carrier In, wherein the polishing while controlling the humidity of the air supplied to a predetermined value from the air injection port.

  According to the present invention, since the high-pressure air that forms a pressure air layer between the protective sheet that contacts the wafer and the back plate is controlled to a predetermined humidity, the protective sheet, the retainer ring, and the wafer are prevented from drying. And the like.

  In the present invention, in the above invention, an ultrasonic humidifier can be used as a humidifying means to control the humidity to a predetermined value, and the humidity can be easily controlled.

  As described above, according to the polishing apparatus and the polishing method according to the present invention, the humidity of the high-pressure air to be supplied is controlled to a predetermined value, so that the drying of the wafer is alleviated.

  Hereinafter, preferred embodiments of a polishing apparatus and a polishing method according to the present invention will be described in detail with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member.

  FIG. 1 is a sectional view showing an embodiment of a wafer polishing apparatus according to the present invention. In the polishing apparatus 10, as shown in the figure, a polishing pad 12 is attached to the surface of a rotating polishing platen 11. Above the polishing pad 12, the wafer carrier 20 is disposed so as to rotate while holding the wafer W and to bring the wafer W into contact with the polishing pad 12. The polishing surface plate 11, the polishing pad 12, the wafer carrier 20, and the like constitute a polishing portion.

  The wafer carrier 20 includes a carrier body 21, a back plate 22, a retainer ring 23, a protective sheet 24 (see FIG. 2), a back plate airbag 28, and a retainer ring airbag 29.

  The back plate airbag 28 is a space formed by the rubber sheet 27 and the carrier body 21, and air is supplied from the air line 50 </ b> C to pressurize the back plate 22 toward the polishing pad 12. Further, the retainer ring airbag 29 is supplied from an air line 50D in a space on the outer peripheral side of the back plate airbag 28 formed by the rubber sheet 27 and the carrier body 21, and the retainer ring 23 is polished. Press toward the pad 12.

  FIG. 2 is an enlarged cross-sectional view showing the pressurizing mechanism portion of the wafer W of the wafer carrier 20. .. Are formed in the outer peripheral portion on the lower surface of the back plate 22 and air outlets 22B, 22B,... Are formed in the central portion, and the air outlets 22A, 22A,. The air outlets 22B, 22B,... Are connected to the main air path 55 via the regulator 51 and the sub air path 52 via the regulator 51. The sub air path 52 is switched by a switching valve 56 to a positive pressure line 53 and a negative pressure line 58 or an air release line 59 via a regulator 57.

  The retainer ring 23 functions to regulate the movement of the wafer W in the radial direction and stabilize the surface of the polishing pad 12 by pressing it.

  The protective sheet 24 is held by the retainer ring 23 at the periphery, and prevents the wafer W from coming into direct contact with the hard back plate 22, and abuts against the wafer W so that the air pressure from the back plate 22 is applied to the wafer W. introduce. The air injected from the back plate 22 forms a pressure air layer between the back plate 22 and the protective sheet 24 and is exhausted to the outside through a gap 23 </ b> A between the back plate 22 and the retainer ring 23.

  The back plate 22 pressurized by the air supplied from the air line 50 </ b> C applies a processing pressure to the wafer W via the pressure air layer formed between the back plate 22 and the protective sheet 24 and the protective sheet 24. By adjusting the air pressure through the main air path 55 and the air pressure through the sub air path 52, the polishing shape of the wafer W is controlled.

  Switching to the positive pressure line 53, the negative pressure line 58 or the atmosphere release line 59, the air pressure by the main air path 55 and the air pressure by the sub air path 52, and the suction pressure by the negative pressure line 58 are optimized by the CPU 60, respectively. Controlled.

  The protective sheet 24 is formed with a plurality of suction ports for wafer suction (not shown), and is used to suck and hold the wafer W when the wafer W is transported. That is, when the wafer W is attracted, the switching valve 56 switches the sub air path 52 to the negative pressure line 58 and transmits the suction force to the wafer W via a plurality of suction ports.

  The main air path 55 incorporates humidifying means for controlling the air humidity to a predetermined value. FIG. 3 shows the humidifying means 70 provided in the main air path 55. As the humidifying means 70, an ultrasonic humidifier 70A is used. As shown in FIG. 3, the ultrasonic humidifier 70 </ b> A includes a tank 71, an ultrasonic vibrator 72 attached to the bottom of the tank 71, a humidity sensor 73 provided inside the tank 71, and a controller 77. .

  The tank 71 is connected to a pure production apparatus via a valve 76, and a predetermined amount of pure water is supplied into the tank 71 so as to be always stored. The tank 71 is connected to a high-pressure air source via a valve 74 and a regulator 75, and is connected to the polishing apparatus 10 with an air hose.

  The pure water in the tank 71 is atomized by the vibration of the ultrasonic vibrator 72 and fills the upper space of the pure water. The high-pressure dry air introduced into the tank 71 is adjusted in humidity here and sent to the polishing apparatus 10.

  The humidity in the tank 71 is detected by the humidity sensor 73, and the data is transmitted to the controller 77. The controller 77 adjusts the humidity in the tank 71 to a predetermined value by controlling the frequency and / or amplitude of the ultrasonic transducer 72 based on the received humidity data in the tank 71.

  The wafer carrier 20 is configured as described above, and the wafer W held by the wafer carrier 20 is pressed against the polishing pad 12 on the polishing surface plate 11 to rotate the polishing surface plate 11 and the wafer carrier 20 while rotating each. By supplying slurry onto the pad 12, the wafer W is polished.

  At this time, the air injected from the back plate 22 to form a pressure air layer between the back plate 22 and the protective sheet 24 of the wafer carrier 20 is discharged from the gap 23A between the back plate 22 and the retainer ring 23 to the outside. Although the air is exhausted, the air is controlled to a predetermined humidity by the humidifying means 70, so that the protective sheet, the retainer ring, the wafer and the like are not dried, and the agglomeration of the slurry and the like is alleviated.

  The wafer carrier 20 for a 300 mm wafer uses a conventional water-repellent film (a Teflon transparent film such as PFA) as the protective sheet 24, and supplies high-pressure air controlled at a temperature of 25 ° C. and a humidity of 60% to the main air path 55. Then, a pressure air layer was formed between the back plate 22 and the protective sheet 24, and a polishing pressure was applied through the pressure air layer to polish the 300 mm wafer W with the thermal oxide film.

  In this polishing, the protective sheet, the retainer ring, the wafer, and the like are not dried, the adhesion and aggregation of the slurry and the like are alleviated, and the defect on the back surface of the wafer W is improved.

  A moisturizing film made of wet foamed polyurethane was attached to the contact surface of the protective sheet 24 of Example 1 with the wafer W, and the same polishing as in Example 1 was performed. At this time, when the experiment was performed by changing the humidity of the air supplied to the main air path 55 as a parameter, a sufficient effect was seen at a humidity of 35%.

  In place of the protective sheet 24 made of the water-repellent film of Example 1, a moisture-retaining film made of wet foamed polyurethane was used as the protective sheet 24, and the humidity of the supplied air was changed as a parameter in the same manner as in Example 2 and experimented. A stable effect was observed at a humidity of 40%.

  As described above, according to the present invention, the supplied high-pressure air is used while being controlled to a predetermined humidity, so that drying of each part of the apparatus and the wafer W is suppressed, and adhesion and aggregation of slurry and the like are alleviated.

  In the above-described embodiment, the ultrasonic humidifier 70A is used as the humidifier 70. However, other known humidifiers such as a fine spray humidifier, a vaporizer humidifier, and a steam humidifier should be used. Can do.

Sectional drawing of the polisher concerning an embodiment of the invention Enlarged sectional view showing the wafer pressing mechanism of the wafer carrier Configuration diagram showing humidification means

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Polishing apparatus, 12 ... Polishing pad, 20 ... Wafer carrier, 22 ... Back plate, 22A / 22B ... Air jet, 23 ... Retainer ring, 24 ... Protection sheet, 70 ... Humidification means, 70A ... Ultrasonic humidification apparatus, W ... wafer

Claims (7)

In a polishing apparatus that polishes a wafer held by a wafer carrier by contacting the rotating polishing pad while supplying slurry,
A polishing apparatus comprising a humidifying means for controlling the humidity inside the polishing apparatus to a predetermined value. In a polishing apparatus having a polishing unit that polishes a wafer held by a wafer carrier in contact with a rotating polishing pad while supplying slurry,
A polishing apparatus comprising a humidifying means for controlling the humidity inside the polishing unit to a predetermined value. In a polishing apparatus that polishes a wafer held by a wafer carrier by contacting the rotating polishing pad while supplying slurry,
The wafer carrier has an air outlet on the lower surface and a back plate that applies a pressing force to the wafer via a pressure air layer formed by air supplied from the air outlet, and moves the wafer in the radial direction. A retainer ring that regulates and presses the polishing pad, and a protective sheet that contacts the wafer and transmits a pressing force applied from the back plate through the pressure air layer to the wafer,
A polishing apparatus comprising a humidifying means for controlling a humidity of air supplied from the air jet outlet to a predetermined value.   The polishing apparatus according to claim 1, wherein the humidifying unit is an ultrasonic humidifier. In the polishing method for polishing the wafer, using a polishing apparatus that polishes the wafer held by the wafer carrier by contacting the polishing pad rotating while supplying the slurry,
A polishing method comprising polishing while controlling the humidity inside the polishing apparatus to a predetermined value. In the polishing method for polishing the wafer, using a polishing apparatus having a polishing unit that polishes the wafer held by the wafer carrier in contact with the rotating polishing pad while supplying the slurry,
A polishing method characterized by polishing while controlling the humidity inside the polishing portion to a predetermined value. A polishing apparatus for polishing a wafer held by a wafer carrier by contacting a rotating polishing pad while supplying slurry, the wafer carrier having an air outlet on a lower surface and supplying from the air outlet A back plate for applying a pressing force to the wafer via a pressure air layer formed by air, a retainer ring for restricting movement of the wafer in the radial direction and pressing the polishing pad, and in contact with the wafer In a polishing method for polishing the wafer, using a polishing apparatus having a protective sheet that transmits a pressing force applied from the back plate through the pressure air layer to the wafer,
A polishing method comprising polishing while controlling the humidity of air supplied from the air outlet to a predetermined value.

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