JP2017162859A - Wafer polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing apparatus capable of conveniently obtaining a desired pressure distribution without remodeling of a polishing head.SOLUTION: A polishing head 10 includes: a carrier 30 supported by a ratable head body 20; an elastic sheet 50 whose peripheral edge is protected by a retainer ring 40 surrounding the carrier 30 and which is arranged opposite to a lower surface 30a of the carrier 30; and an elastic press member 60 which is fixed to an arbitrary position of the lower surface 30a of the carrier 30 and presses a wafer W to the polishing pad 5 via the elastic sheet 50.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wafer polishing apparatus, and more particularly to a wafer polishing apparatus that performs CMP processing on a wafer.

  In the semiconductor manufacturing field, a wafer polishing apparatus for flattening a semiconductor wafer such as a silicon wafer (hereinafter referred to as “wafer”) is known.

  The polishing apparatus described in Patent Document 1 is a polishing apparatus to which chemical mechanical polishing, so-called CMP (Chemical Mechanical Polishing) technology is applied. In the polishing head of this polishing apparatus, air is introduced into an air chamber formed between the carrier and the rubber sheet, and air is independently introduced into a plurality of airbags arranged on the lower surface of the carrier. . The pressing force by which the rubber sheet presses the wafer is locally adjusted by the amount of expansion of the airbag according to the pressure of the air supplied to the airbag, and the airbag is arranged on the rubber sheet pressing the wafer according to the arrangement of the airbag. A pressure distribution can be formed.

  In such a polishing apparatus, since the airbag is fixed to the carrier via a fastener or the like that can be fitted into a mounting groove or the like formed on the lower surface of the carrier, the carrier has a shape that takes into account the fastener or the like. Since the mold is manufactured each time, there is a problem that a plurality of polishing heads must be prepared when the pressure distribution is changed according to the type of wafer.

  For such a problem, in order to form a plurality of pressing areas by diverting one polishing head, a plurality of mounting grooves are prepared in advance, and the pressing area regulating member is arranged so as to form a desired pressing area. It is possible. In the polishing apparatus described in Patent Document 2, the air bag is supported at its periphery by a pressing region restricting member, and the range in which the wafer is pressed is restricted. The pressing region restricting member is fitted to an attachment groove formed in the carrier at the convex portion, and is fixed to the carrier with a bolt. A plurality of mounting grooves are arranged, and the pressure distribution formed on the elastic sheet can be changed by changing the mounting groove into which the pressing region regulating member is fitted.

Japanese Patent No. 3683149 Japanese Patent No. 3520916

  However, in the polishing apparatus described in Patent Document 2 as described above, the air line in the carrier that supplies air to the airbag is connected to the port of the external air supply source, so that the number of installed airbags is increased. Since the upper limit is limited by the number of ports, it is difficult to form all the various pressure distributions with one carrier. In addition, when adding a port for pumping air, an electropneumatic regulator, or the like, there is a problem that the polishing head must be significantly modified.

  Therefore, a technical problem to be solved arises that a desired pressure distribution can be easily obtained without remodeling the polishing head, and the present invention aims to solve this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a wafer polishing apparatus that polishes the wafer by pressing the wafer mounted on the polishing head against the polishing pad with air. The polishing head includes a carrier supported by a rotatable head body, an elastic sheet that is held at its periphery by a retainer ring that surrounds the carrier, and is disposed to face the lower surface of the carrier, and the carrier And an air supply means for supplying air to an air chamber formed between the elastic sheet and the elastic sheet, and is fixed to an arbitrary position on the lower surface of the carrier and presses the wafer against the polishing pad via the elastic sheet A wafer polishing apparatus comprising an elastic pressing member.

  According to this configuration, since the elastic pressure member is fixed to an arbitrary position on the lower surface of the carrier, the pressure distribution can be appropriately changed according to the arrangement of the elastic pressure member. It can be formed simply by changing the installation position.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, the elastic pressing member provides a wafer polishing apparatus that is adhered to the lower surface of the carrier via an adhesive.

  According to this configuration, in addition to the effect of the invention described in claim 1, since the elastic pressing member is attached to the lower surface of the carrier via the adhesive, it is easy to change the arrangement of the elastic pressing member. A simple pressure distribution can be formed easily.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the elastic pressing member communicates with the adjacent air chambers that are partitioned with the elastic pressing member interposed therebetween. A wafer polishing apparatus in which is formed.

  According to this configuration, in addition to the effect of the first or second aspect of the invention, the air supplied from the air supply means diffuses into the air chamber through the ventilation groove, so that the air goes to the entire air chamber. Since it is suppressed that a pressure falls locally without reaching, a desired pressure distribution can be formed reliably.

  According to a fourth aspect of the invention, in addition to the configuration of the first aspect of the invention, the pressing force with which the elastic pressing member presses the wafer is the thickness, hardness, or hardness of the elastic pressing member. Provided is a wafer polishing apparatus which can be adjusted by changing at least one of materials.

  According to this configuration, in addition to the effect of the invention according to any one of claims 1 to 3, at least one of the thickness, hardness, or material of the elastic pressing member is changed so that the elastic pressing member is interposed between the elastic sheets. Since the pressing force applied to the wafer can be adjusted, various pressure distributions can be easily formed.

  In the present invention, since the elastic pressing member can be fixed at an arbitrary position on the lower surface of the carrier, the pressure distribution can be arbitrarily changed according to the arrangement of the elastic pressing member, and thus various pressure distributions can be easily formed. Can do.

1 is a perspective view showing a wafer polishing apparatus according to an embodiment of the present invention. The longitudinal cross-sectional view which shows the principal part of a grinding | polishing head typically. The longitudinal cross-sectional view and partial enlarged view which show typically the front-end | tip of a grinding | polishing head. FIG. 4 is a bottom view showing the polishing head of FIG. 3. The graph which shows the removal rate (Removal rate) by the pressure distribution formed in the grinding | polishing head of FIG. The graph which shows the removal rate (Removal rate) by the pressure distribution formed in the grinding | polishing head used for the conventional wafer grinding | polishing apparatus.

  In order to achieve the object of easily obtaining a desired pressure distribution without modification of the polishing head, the wafer polishing apparatus according to the present invention presses the wafer mounted on the polishing head against the polishing pad by air. A polishing head is an elastic sheet that has a carrier supported by a rotatable head body and a retainer ring that surrounds the carrier, the periphery of which is disposed opposite the lower surface of the carrier And an air supply means for supplying air to an air chamber formed between the carrier and the elastic sheet, and an elastic press fixed to an arbitrary position on the lower surface of the carrier and pressing the wafer against the polishing pad via the elastic sheet It implement | achieves by providing a member.

  Hereinafter, a wafer polishing apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following examples, when referring to the number, numerical value, quantity, range, etc. of the constituent elements, the specific number is used unless otherwise specified and clearly limited to a specific number in principle. It is not limited, and it may be a specific number or more.

  In addition, when referring to the shapes and positional relationships of components, etc., those that are substantially similar to or similar to the shapes, etc., unless otherwise specified or otherwise considered in principle to be apparent. Including.

  In addition, the drawings may be exaggerated by enlarging characteristic portions in order to make the features easy to understand, and the dimensional ratios and the like of the constituent elements are not always the same. In the cross-sectional view, hatching of some components may be omitted in order to facilitate understanding of the cross-sectional structure of the components. In this embodiment, the terms “upper” and “lower” correspond to the upper and lower parts in the vertical direction.

  FIG. 1 is a perspective view showing a basic configuration of the wafer polishing apparatus 1. The wafer polishing apparatus 1 is a CMP polishing apparatus and polishes the wafer W flatly. The wafer polishing apparatus 1 includes a platen 2 and a polishing head 10.

  The platen 2 is formed in a disk shape and is connected to a rotating shaft 3 disposed below the platen 2. As the rotary shaft 3 is rotated by driving the motor 4, the platen 2 rotates in the direction of the arrow D1 in FIG. A polishing pad 5 is affixed to the upper surface of the platen 2, and a CMP slurry, which is a mixture of an abrasive and a chemical, is supplied onto the polishing pad 5 from a nozzle (not shown).

  The polishing head 10 is formed in a disk shape having a smaller diameter than the platen 2, and is connected to a rotating shaft 10 a disposed above the polishing head 10. As the rotary shaft 10a rotates by driving a motor (not shown), the polishing head 10 rotates in the direction of the arrow D2 in FIG. The polishing head 10 can be raised and lowered in the vertical direction V by a lifting device (not shown). The polishing head 10 descends when pressing the wafer W and presses the wafer W against the polishing pad 5.

  The operation of the wafer polishing apparatus 1 is controlled by control means (not shown). The control means controls each component constituting the wafer polishing apparatus 1. The control means is, for example, a computer, and includes a CPU, a memory, and the like. The function of the control means may be realized by controlling using software, or may be realized by operating using hardware.

  Next, the polishing head 10 will be described. FIG. 2 is a longitudinal sectional view schematically showing the main part of the polishing head 10. FIG. 3 is a longitudinal sectional view schematically showing the tip of the polishing head 10 and a partially enlarged view thereof. FIG. 4 is a bottom view of the polishing head 10.

  The polishing head 10 includes a head main body 20, a carrier 30, a retainer ring 40, and an elastic sheet 50.

  The head body 20 is connected to the rotation shaft 10a and rotates together with the rotation shaft 10a. The head main body 20 is connected to a carrier 30 disposed below the head main body 20 via a rotating unit 21, and the head main body 20 and the carrier 30 rotate in conjunction with each other.

  The carrier 30 is provided with eight air lines 31 that are arranged at equal intervals around the periphery of the carrier 30. The lower end of the air line 31 opens into an air chamber A formed between the lower surface 30 a of the carrier 30 and the elastic sheet 50. The air line 31 is connected to an air supply source as air supply means (not shown), and air is introduced into the air chamber A through the air line 31. The pressure of the air supplied to the air line 31 is adjusted by a regulator (not shown).

  Carrier pressing means 32 is provided between the head main body 20 and the carrier 30. The carrier pressing means 32 is an airbag or the like that is inflated by air supplied from an air supply source (not shown). The pressure of the air supplied from the air supply source is adjusted by a regulator (not shown). The carrier pressing means 32 presses the wafer W against the polishing pad 5 via the carrier 30 according to the pressure of the supplied air.

  The retainer ring 40 is disposed so as to surround the carrier 30. The retainer ring 40 is fixed to the retainer ring holder 41 with a bolt (not shown). The peripheral edge of the elastic sheet 50 is sandwiched between the retainer ring 40 and the retainer ring holder 41. The retainer ring holder 41 is attached to the retainer pressing member 43 via a snap ring 42. A retainer pressing means 44 is provided between the head body 20 and the retainer pressing member 43. Reference numeral 45 denotes a cover that covers the upper portion of the snap ring 42.

  The retainer pressing means 44 is an airbag or the like that is inflated by air supplied from an air supply source (not shown). The pressure of the air supplied from the air supply source is adjusted by a regulator (not shown). The retainer pressing means 44 presses the retainer ring 40 against the polishing pad 5 via the retainer pressing member 44 according to the pressure of the supplied air.

  The elastic sheet 50 is disposed so as to face the lower surface 30 a of the carrier 30. The elastic sheet 50 is made of polyethylene terephthalate resin (PET), fluororesin (PFA), or poniphenylene sulfide (PPS). PFA has a low water absorption rate, is moderately flexible and is resistant to elongation and deformation. PPS has a low water absorption rate, is strong against elongation and deformation, and is less expensive than PFA.

  Four elastic pressing members 60 arranged coaxially are provided on the lower surface 30 a of the carrier 30. The elastic pressing member 60 is disposed on the same axis as the rotation axis of the polishing head 10 and defines the air chamber A. The elastic pressing member 60 disposed in the center in plan view is formed in a disc shape. Further, the other three elastic pressing members 60 are formed in an annular shape having different diameters.

  The elastic pressing member 60 is fixed to the lower surface 30a of the carrier 30, and is preferably detachably attached to the carrier 30 with a two-component epoxy resin adhesive or the like. Thereby, the arrangement position of the elastic pressing member 60 can be arbitrarily changed.

  As shown in FIG. 3, the elastic pressing member 60 has a lower surface 30a slightly protruding below the rim 33 of the carrier 30 by a protruding amount t, and the lower portion of the elastic pressing member 60 is elastically deformed by the pressing force. The wafer W is pressed against the polishing pad 5 through the elastic sheet 50. Therefore, the range in which the wafer W is pressed can be increased or decreased by increasing or decreasing the surface area of the lower surface 60a of the elastic pressing member 60. That is, a portion of the wafer W that is locally pressed with a pressure equal to or higher than the air pressure supplied to the air chamber A by appropriately changing the arrangement, the number of the elastic pressing members 60, the installation area in contact with the elastic sheet 50, or the like. Can be selected.

  As shown in FIG. 4, a ventilation groove 61 extending along the radial direction of the elastic pressing member 60 is formed on the lower surface 60 a of the elastic pressing member 60. The ventilation groove 61 communicates adjacent air chambers A partitioned with the elastic pressing member 60 interposed therebetween. As a result, the air supplied from the air line 31 disposed on the outer peripheral side of the outermost elastic pressing member 60 diffuses throughout the air chamber A through the ventilation groove 61 of the elastic pressing member 60.

  The pressing force with which the elastic pressing member 60 presses the wafer W can be adjusted by changing at least one of the thickness, hardness or material of the elastic pressing member 60. When the elastic pressing member 60 is thickened, the protrusion amount t by which the lower surface 60a of the elastic pressing member 60 protrudes from the rim 33 increases, so that the pressing force with which the elastic pressing member 60 presses the wafer W increases.

  Further, when the hardness of the elastic pressing member 60 is increased, the elastic pressing member 60 is less likely to be elastically deformed, so that the pressing force with which the elastic pressing member 60 presses the wafer W increases. The hardness HS of the elastic pressing member 60 is preferably 20 ° ≦ HS ≦ 70 ° (JIS-A), for example. If the hardness HS of the elastic pressing member 60 is set to be less than 20 °, the elastic pressing member 60 is too soft and it is difficult to transmit the pressing force to the wafer W. On the other hand, if the hardness HS of the elastic pressing member 60 is set to be larger than 70 °, the elastic pressing member 60 is too hard and excessive pressing force is difficult to escape when the wafer W is polished.

  Further, when a hard resin is used for the elastic pressing member 60, the elastic pressing member 60 is difficult to be elastically deformed, so that the pressing force with which the elastic pressing member 60 presses the wafer W increases. Examples of the material of the elastic pressing member 60 include ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), and silicon rubber.

  FIG. 5 shows a removal rate (removal rate) due to pressure distribution formed on the polishing head 10 in which three elastic pressing members 60 having different diameters are coaxially arranged. Hereinafter, when distinguishing each of the three elastic pressing members 60 shown in FIG. 5, a to c are added to the end of the numbers representing the members in order from the inner side, and the reference numerals are used.

  In the polishing head 10 shown in FIG. 5, the pressing force of the elastic pressing member 60a is the strongest, and the elastic pressing member 60c is the weakest. On the other hand, FIG. 6 shows a removal rate (removal rate) by pressure distribution of a conventional polishing head 90 as a comparative example of the present invention. The polishing head 90 is not provided with a configuration for locally applying a pressing force, and the pressure distribution formed on the polishing head 90 is an air chamber A ′ formed between the carrier 91 and the elastic sheet 92. It becomes uniform by the air introduced inside.

  In order to obtain the removal rate by the pressure distribution as shown in FIG. 5, it is conceivable that the elastic pressing member 60a is formed to be the thickest, and the elastic pressing member 60b and the elastic pressing member 60c are made thinner in this order. It is also conceivable that the elastic pressing member 60a is formed to be the hardest, and the elastic pressing member 60b and the elastic pressing member 60c are softened in this order. Furthermore, it is conceivable to employ the hardest material for the elastic pressing member 60a and to employ soft materials in the order of the elastic pressing member 60b and the elastic pressing member 60c. In addition, the pressure distribution formed on the elastic sheet 50 can be adjusted more flexibly by changing two or more of the thickness, hardness or material of the elastic pressing member 60 in combination.

  Thus, in the wafer polishing apparatus 1 described above, the elastic pressure member 60 can be fixed to an arbitrary position on the lower surface 30 a of the carrier 30, so that the pressure distribution can be arbitrarily changed according to the arrangement of the elastic pressure member 60. Therefore, various pressure distributions can be easily formed.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 1 ... Wafer polisher 2 ... Platen 3 ... Rotating shaft 4 ... Motor 5 ... Polishing pad 10 ... Polishing head 10a ... Rotary shaft 20 ... Head main body 21 ... Rotating part 30 ... Carrier 30a ... (under the carrier) 31 ... Air line 32 ... Carrier pressing means 33 ... Rim 40 ... Retainer ring 41 ... Retainer ring holder 42 ... Snap ring 43 ... Retainer pressing member 44 ... Retainer pressing means 50 ... Elastic sheet 60 ... Elastic pressing member 60a ... (lower surface of elastic pressing member) 61 ... Ventilation groove A ...・ Air chamber V ... Vertical direction W ... Wafer

Claims (4)

A wafer polishing apparatus that polishes the wafer by pressing the wafer mounted on the polishing head against the polishing pad with air,
The polishing head is
A carrier supported by a rotatable head body;
An elastic sheet having a peripheral edge held by a retainer ring surrounding the carrier and disposed opposite to the lower surface of the carrier;
Air supply means for supplying air to an air chamber formed between the carrier and the elastic sheet;
An elastic pressing member fixed to an arbitrary position on the lower surface of the carrier and pressing the wafer against the polishing pad via the elastic sheet;
A wafer polishing apparatus comprising:   The wafer polishing apparatus according to claim 1, wherein the elastic pressing member is adhered to the lower surface of the carrier via an adhesive.   The wafer polishing apparatus according to claim 1, wherein the elastic pressing member is formed with a ventilation groove communicating the adjacent air chambers partitioned with the elastic pressing member interposed therebetween.   4. The pressing force with which the elastic pressing member presses the wafer can be adjusted by changing at least one of the thickness, hardness or material of the elastic pressing member. The wafer polishing apparatus as described.