JP5183169B2 - Wafer processing equipment - Google Patents

Description

  The present invention relates to a wafer processing apparatus provided with an apparatus for adsorbing and holding a wafer and grinding the back surface thereof, and more particularly, to a technique for preventing suction of grinding dust into an adsorbing portion that adsorbs and holds a wafer.

  In the semiconductor manufacturing field, wafers tend to increase in size year by year, and wafers are becoming thinner to increase mounting density. In order to thin the wafer, so-called back grinding is performed to grind the back surface of the semiconductor wafer. For example, Patent Document 1 discloses a technique for grinding a back surface of a wafer by attracting and holding the wafer on a chuck using a vacuum suction force.

  Grinding debris such as silicon grains generated during grinding of the wafer may enter the suction portion due to vacuum suction force, which causes problems such as reduction in suction force. Thus, for example, Patent Document 2 discloses a technique in which an annular groove is formed on the outer periphery of a stage having a vacuum suction portion, and pure water is overflowed from the groove to seal the outer periphery of the wafer.

JP 2000-21951 A Japanese Patent Laid-Open No. 10-135316

  The wafer size includes a small (small diameter) having a diameter of about 200 mm (8 inches) and a large (large diameter) having a diameter of about 300 mm (12 inches). It is desirable that both of these two types of wafers can be back-ground. Therefore, in the conventional wafer processing apparatus, for example, as shown in FIG. 6, a circular inner suction portion 134 having the same diameter as that of the small diameter wafer 18a and a diameter of the large diameter wafer 18b are substantially equal. A stage 124 is provided to support a ring-shaped outer suction portion 136 having an outer diameter. Both the inner suction portion 134 and the outer suction portion 136 are formed of a porous material such as porous alumina, and are configured to generate a suction force by the vacuum means 138 schematically illustrated so as to suck the wafer 18a or 18b during backside grinding. ing.

  When the wafer is backside ground using the vacuum chuck as described above, some of the grinding scraps such as silicon particles generated by grinding wrap around from the outer periphery of the wafer to the bottom of the wafer along with the processing liquid. Therefore, it may be sucked into the inner suction portion or the outer suction portion. Since the adsorbing part is made of a porous material as described above, the sucked silicon particles and the like are not sucked up to the vacuum means and may stay in the porous material. If a certain amount of silicon particles or the like stays in the porous body, the suction force may be reduced, and the wafer may be displaced or dropped during backside grinding, making it impossible to perform desired grinding. Moreover, it is very difficult to clean, that is, remove the silicon particles once sucked into the porous body.

  Therefore, an object of the present invention is to provide a wafer processing apparatus having a function of preventing silicon particles generated by grinding from being sucked into an adsorption portion when the wafer is back-ground.

In order to achieve the above object, the invention described in claim 1 is a wafer processing apparatus including a back surface grinding unit that grinds the back surface of a large-diameter and a small-diameter wafer having a circuit pattern formed on the surface thereof. The back surface grinding unit has a suction part for sucking and holding a wafer and a vacuum means for generating a suction force on the suction part, and the suction part sucks and holds both the large-diameter and small-diameter wafers. A substantially circular inner suction portion, and a substantially ring-shaped outer suction portion having an inner diameter somewhat larger than the diameter of the inner suction portion and capable of sucking and holding only the large-diameter wafer. An opening for sucking fluid is provided in at least one of the annular region between the outer suction portion and the outer periphery of the outer suction portion, and an opening between the inner suction portion and the outer suction portion is provided. Ring between At least the wafer near the opening provided in the range, the porous material is provided with silicon grains having a mesh enough to pass, to provide a wafer processing apparatus.

The invention according to claim 2 is the wafer processing apparatus according to claim 1, wherein at least one of an annular region between the inner suction portion and the outer suction portion and a region adjacent to the outer periphery of the outer suction portion. Provided is a wafer processing apparatus in which a concave portion is formed on a surface .

According to a third aspect of the present invention, in the wafer processing apparatus according to the first or second aspect , when the suction unit holds and holds the small-diameter wafer, the outer suction unit discharges fluid. A configured wafer processing apparatus is provided.

  According to the present invention, when the suction unit holds and holds the small-diameter wafer, the portion of the suction unit that does not suck and hold the small-diameter wafer is configured to discharge the fluid. It is possible to prevent clogging and the like from being caused by suction of grinding scraps such as silicon grains into the suction portion that holds the suction.

  At least one of the annular region between the inner suction portion and the outer suction portion and the region adjacent to the outer periphery of the outer suction portion is provided with an opening for discharging or sucking fluid, thereby being sucked into the suction portion. Silicon particles or the like can be blown to the outside or sucked into the region before being sucked into the adsorption portion.

  Before a certain amount of silicon particles or the like is sucked into the adsorbing part by forming a recess in at least one surface of the annular area between the inner adsorbing part and the outer adsorbing part and the area adjacent to the outer periphery of the outer adsorbing part Can be collected.

  By providing a porous material at least near the wafer in the opening provided in the annular region between the inner suction portion and the outer suction portion, it is possible to support a large-diameter wafer during backside grinding also in the opening. The deformation of the wafer due to the pressure applied to the wafer during grinding can be prevented.

  FIG. 1 is a schematic plan view of a wafer processing apparatus to which the present invention can be applied. The wafer processing apparatus 10 includes a back surface grinding unit 12 for grinding the back surface of the wafer, and a dicing tape attaching unit 14 for attaching a dicing tape to the wafer. Each of these units is controlled by a control device (not shown). The wafer processed by the dicing tape attaching unit 14 is transported to the dicing unit 16 schematically shown and diced.

  The back grinding unit 12 is provided with wafer cassettes 20 </ b> A and 20 </ b> B that store a plurality of wafers 18. The wafers 18 are taken out from the wafer cassettes 20A and 20B one by one by the robot arms 22A and 22B. Next, the wafer 18 is sucked and held by the suction portion 26 of the stage 24 with the back surface thereof facing upward. A plurality of circuit patterns (not shown) are already formed on the surface of the wafer 18, and a surface protection film (not shown) for protecting the circuit patterns is attached to the wafer surface. The wafer 18 includes at least the above-described small-diameter wafer 18a and large-diameter wafer 18b.

  Thereafter, the grinding portions 28A and 28B of the back surface grinding unit 12 are rotationally driven to grind the back surface of the wafer 18. By this grinding, the thickness of the wafer 18 is reduced to a desired thickness.

  When the back surface grinding of the wafer 18 is completed, the wafer 18 is transferred from the back surface grinding unit 12 to the dicing tape attaching unit 14 by the robot arm 30, and the dicing tape 32 is attached to the back surface of the wafer 18 by a known method. Next, the surface protective film affixed to the surface of the wafer 18 is peeled off by a known method, and then the wafer 18 is conveyed to the dicing unit 16 and diced to a predetermined size.

  FIG. 2 is a cross-sectional view of one of the suction portions 26 provided on the stage 24 of the back grinding unit 12 as seen from the lateral direction. The suction part 26 of the stage 24 is formed of a porous material such as porous alumina, for example. Specifically, the suction part 26 has a substantially circular inner suction part 34 having a diameter equal to or slightly smaller than the diameter of a small diameter wafer, and a large diameter. A substantially ring-shaped outer suction portion 36 having an outer diameter equal to or somewhat smaller than the diameter of the wafer and an inner diameter somewhat larger than the diameter of the inner suction portion 34. When back grinding a small diameter wafer 18a, only the inner suction part 34 is evacuated by a vacuum means 38 such as a vacuum pump schematically shown. On the other hand, when grinding a large diameter wafer 18b, the inner suction part 34 and the outer suction part 34 are sucked. Both parts 36 are evacuated. The wafer 18a or 18b is sucked and held by the suction portion 26 by the suction force generated in this way.

  Here, as described with reference to FIG. 6, silicon particles and the like generated when the small-diameter wafer 18 a is subjected to back surface grinding enter the inner suction portion 34 by the suction force of the inner suction portion 34 and become porous. It may cause clogging of substances, that is, decrease in adsorption power. Therefore, the present invention solves this problem by the means described below.

  In the first embodiment, as shown in FIG. 2, the outer suction portion 36 that is not used in the back surface grinding of the small-diameter wafer 18a has a function of purging fluid such as water or air. As a specific example, the fluid supply source 40 shown schematically is fluidly connected to the outer suction portion 36, and when grinding the small diameter wafer 18a, the valve 42 is opened and the valve 44 is closed, and the large diameter wafer 18b is ground. On the contrary, the valve 44 may be opened and the valve 42 may be closed. According to such a configuration, during grinding of the small-diameter wafer 18a, the fluid can be purged from the surface of the outer suction portion 36, and the silicon particles that are going to enter the inner suction portion 34 are actively blown to the outside. be able to.

  As shown in FIG. 2, the inner suction portion 34 has a substantially circular shape capable of sucking and holding both the large and small diameter wafers 18a and 18b, while the outer suction portion 36 is somewhat larger than the diameter of the inner suction portion 34. It has a substantially ring shape having an inner diameter and capable of sucking and holding only the large-diameter wafer 18b. Therefore, the above-described purge function can be given to the solid annular region 46 formed between the inner suction portion 34 and the outer suction portion 36. In the second embodiment shown in the partially enlarged view of FIG. 3, an opening 48 through which fluid can flow is provided from the opening 48 in an annular region 46 made of alumina or the like between the inner suction portion 34 and the outer suction portion 36. A fluid such as water or air is purged from a fluid supply source (not shown). The opening 48 can be formed in various shapes. For example, the opening 48 may have a circular shape provided at an appropriate interval in the circumferential direction of the annular region 46, or a ring shape formed over the entire circumferential direction of the annular region 46. There may be. According to the second embodiment, since the fluid can be sprayed near the outer periphery of the small-diameter wafer 18a where the silicon particles are likely to go around, it is possible to more effectively prevent the silicon particles from entering the inner adsorption portion 34. it can.

  As shown in FIG. 3, a guide member 50 that suitably changes the flow direction of the purged fluid can be provided in the opening 48. In the example of FIG. 3, the guide member 50 has inclined surfaces 52 and 54 that are inclined inward and outward, respectively, in a side sectional view. With the inclined surface 52 inclined inward, fluid can be discharged from the lower side toward the outer peripheral end portion 56 of the small-diameter wafer 18a, and the traveling direction of the silicon grains toward the inner adsorption portion 34 can be changed more effectively. be able to. On the other hand, the inclined surface 54 inclined outward can smooth the flow of the silicon particles that are about to leave the wafer according to the flow of the grinding water 58 supplied from the grinding unit.

  FIG. 4 is a partially enlarged view showing the third embodiment. In the third embodiment, an opening 48 provided in the annular region 46 between the inner suction part 34 and the outer suction part 36 is sucked by a vacuum means or the like (not shown) contrary to the second embodiment. Used as a suction part. In this way, silicon particles or the like generated by the back surface grinding can be sucked into the opening 48 before being sucked into the inner suction portion 34. Even when the opening 48 is used as a suction portion, a guide member that appropriately defines the flow direction of the fluid to be sucked may be provided.

  The annular region 46 acts as a support for supporting the wafer when the large-diameter wafer is ground on the back surface. Therefore, when the opening area of each opening 48 is relatively large, the large-diameter wafer may be deformed by the pressure that can be received during grinding by the above-described grinding portion 28A or 28B (see FIG. 1). Therefore, as shown in FIG. 4, a porous material 60 having openings that are coarse enough to allow silicon particles to pass therethrough can be provided at least in a region near the wafer in the opening 48. Also, a porous material can be used when fluid is discharged from the opening 48 as in the second embodiment described above, but when the opening 48 is not used as a suction portion, the porous material is It is not necessary to have a coarse opening that allows the silicon grains to pass through.

  FIG. 5 is a partially enlarged view showing the fourth embodiment. In the fourth embodiment, a concave portion 62 such as a groove is provided in the annular region 42 between the inner suction portion 34 and the outer suction portion 36. By collecting silicon particles in the recess, entry into the inner suction portion 34 is prevented. The concave portion 62 has a substantially vertical wall portion 64 on the inner suction portion 34 side so that the silicon particles collected in the concave portion can be prevented from moving toward the inner side in the radial direction of the wafer (the inner suction portion 34). Is preferred. In addition, since the trapping effect is lost when the silicon particles fill the recess 62, it is necessary to clean the recess every appropriate time interval or every time a predetermined number of wafers are ground. Accordingly, it is preferable that the outer suction portion 36 side has a relatively gentle inclined portion 66 so that the silicon particles collected in the recess can be cleaned relatively easily.

  Obviously, the first to fourth embodiments described above can be appropriately combined. For example, the purge function of the first embodiment and the suction function of the third embodiment may be combined, or an opening having a purge function or a suction function according to the second or third embodiment is provided. You may provide the recessed part which concerns on 4th Embodiment in the surface of solid parts other than a part.

  As mentioned above, although each embodiment demonstrated the case where the small diameter wafer was ground back, about 2nd-4th embodiment, it can apply also when back grinding the large diameter wafer. That is, in the second to fourth embodiments, the openings and recesses having the same functions as the openings 48 and the recesses 62 provided in the annular region 46 between the inner suction part 34 and the outer suction part 36 are used as outer suctions. By providing it in the region 68 (see FIG. 2) of the stage 24 adjacent to the outer peripheral portion of the portion 36, substantially the same effect as that of the above-described embodiment can be obtained even when grinding a large-diameter wafer.

1 is a schematic plan view of a wafer processing apparatus to which the present invention can be applied. It is sectional drawing which looked at the adsorption | suction part vicinity of the wafer processing apparatus which concerns on 1st Embodiment based on this invention from the horizontal direction. It is the elements on larger scale which looked at the adsorption part neighborhood of the wafer processing device concerning a 2nd embodiment concerning the present invention from the horizontal direction. It is the partial expanded sectional view which looked at the adsorption | suction part vicinity of the wafer processing apparatus which concerns on the 3rd Embodiment which concerns on this invention from the horizontal direction. It is the elements on larger scale which looked at the adsorption part neighborhood of the wafer processing apparatus concerning a 4th embodiment concerning the present invention from the horizontal direction. It is sectional drawing which looked at the adsorption | suction part vicinity of the conventional wafer processing apparatus from the horizontal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wafer processing apparatus 12 Back surface grinding unit 14 Dicing tape sticking unit 16 Dicing unit 18 Wafer 24 Stage 26 Adsorption part 34 Inner adsorption part 36 Outer adsorption part 38 Vacuum means 40 Fluid supply source 46 Annular area 48 Opening part 50 Guide member 60 Porous material

Claims (3)

A wafer processing apparatus provided with a back surface grinding unit for grinding a back surface of a large-diameter and small-diameter wafer having a circuit pattern formed on the surface,
The back surface grinding unit has a suction part for sucking and holding the wafer, and a vacuum means for generating a suction force in the suction part,
The suction part has a substantially circular inner suction part capable of sucking and holding both the large diameter and small diameter wafers, and an inner diameter somewhat larger than the diameter of the inner suction part, and can suck and hold only the large diameter wafer. A substantially ring-shaped outer suction portion, and for sucking fluid into at least one of an annular region between the inner suction portion and the outer suction portion and a region adjacent to the outer periphery of the outer suction portion. An opening is provided,
At least in the vicinity of the wafer in the opening provided in the annular region between the inner adsorption portion and the outer adsorption portion, a porous material having an opening that allows silicon particles to pass therethrough is provided.
Wafer processing equipment. 2. The wafer processing apparatus according to claim 1 , wherein a recess is formed on at least one surface of an annular region between the inner suction portion and the outer suction portion and a region adjacent to the outer periphery of the outer suction portion . The wafer processing apparatus according to claim 1, wherein the outer suction unit is configured to discharge a fluid when the suction unit holds the small-diameter wafer .

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