JPH03104567A - Grinding wheel and grinding method - Google Patents

Abstract

PURPOSE:To unify wheel spindles and miniaturize a grinding machine by integrally providing a rough grinding part and a finish grinding part on one base metal part. CONSTITUTION:The back surface 12 of a wafer W is ground with diamond by a rough grinding part 2 to remove an oxide film adhered thereon. After the completion of removal of the oxide film on the back surface 12, a wheel spindle S is once raised, and the rotations of a rotating shaft 15 and the wheel spindle S are stopped. A vacuum chuck 13 is moved to situate one of grind-stone pieces 10... on the axial line 15a of the rotating shaft 15. Hence, all the grindstone pieces 10 pass the axial line 15a in accordance with the rotation of the wheel spindle S. The rotating shaft 15 and the wheel spindle S are then rotated, and the wheel spindle S is lowered. The wafer W held by the vacuum chuck 13 is pressed onto a finish grinding part 3, and finish grinding is started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a workpiece and a grinding force method suitable for backside grinding of silicon (8i) wafers.

(Prior Art) Semiconductor devices are generally manufactured from Si wafers, and the Si wafers that have gone through the device process have an oxide film (SiO2) formed on the back surface. The back side of the Si wafer with such an oxide film attached will be treated in the next step.
Grinding is done. This grinding process was performed in two steps: rough grinding and finish grinding, so it was hardly affected by the oxide film (8i02).

(Problems to be Solved by the Invention) However, conventional back grinders for Si wafers are large and have a high M content, and therefore have the disadvantage that they cannot be made in-line. Therefore, recently there has been an increasing demand for downsizing of back grinders. To downsize the back grinder,
Reducing the number of grinding wheel axes, that is, making it uniaxial, is an essential condition, and for this purpose, a grinding wheel that can be used for both rough grinding and finish grinding, and can also grind both oxidized M (S'Os) and silicon (Si). A workpiece is required.

By the way, the workpiece for the l-axis must be fine-grained diamond abrasive grains due to the requirement for roughness of the surface to be processed of the wafer. However, fine-grained diamond whetstones have drawbacks such as rapid deterioration, clogging, and significantly shortened whetstone life, so they could not be used due to processing costs and processing efficiency.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a workpiece and a grinding method that can be grinded with a long life and high efficiency.

[Structure of the invention]

(Means and effects for solving the line problem) This invention provides a rough grinding section and a finish grinding section integrally in one base metal part, and performs rough grinding and finishing on one workpiece. Since finishing grinding can be performed, it is possible to downsize the grinding machine and inline it into an automated process.

(Example) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 show a workpiece (G
) is shown. This workpiece (G) includes a disk-shaped base metal part (1), a rough grinding part (2) laid on the lower end surface of the base metal part (1) excluding the peripheral edge, and It is composed of a ring-shaped finish grinding part (3) surrounding the part (2) and coaxially planted on the peripheral edge of the base metal part (1). Thus, a circular recess (4) having a depth fwm, for example, is provided at the lower end of the base metal part (1), leaving the peripheral edge. The inner diameter of this recess (4) is determined by the diameter of the wafer (W), as described later.
) is provided larger than the diameter of the

Furthermore, the outer circumference of this recess {4} protrudes in a ring shape with respect to the bottom surface (5) of the recess (4), and the supporting wall (6)
It becomes. Moreover, the base metal part (1} has one end opening at the upper end surface of the base metal part (1), and the other end opening at the bottom surface (5) of the recessed part (4).
) is provided with a through hole (7) that opens into the hole (7). In addition, a ring-shaped groove (8) is carved in a portion of the bottom surface (51 adjacent to the support wall (6)).In addition, a ring-shaped groove (8) and a through hole are formed in the bottom surface (5). A radial groove (9)... is carved that communicates with the through hole (7).The groove near the opening of the through hole (7) is enlarged, and abnormal wear of the grindstone occurs in the portion where the circumferential speed is 0. This is to prevent the rough grinding part (2) from forming on the bottom surface (5) except for the ring groove (8) and the radial groove (9). This rough grinding part (2) # is made by electro-depositing diamond abrasive grains with a mesh size of 150 or #23o using nickel (Ni).

The thickness of the roughly ground portion (2) is, for example, J-shaped, and is smaller than the depth of the recessed portion (4).

On the other hand, the finishing grinding part (3) is made up of grindstone pieces αQ set up in segments at regular intervals on the ring-shaped end face of the support wall (6). The workpiece (G) is a segment-shaped cup grindstone. And, between these grindstone piece recesses, there is a gap 0υ whose width in the circumferential direction is, for example, jI1 ml.

In addition, these grindstone pieces 01... are made by bonding diamond abrasive grains with a mesh size of 1500 or 2000 using vitrified bond and forming them into segments, and the thickness is, for example, 3 m and the height is For example, it is 5■. Therefore, the grinding surface (2a) of the rough grinding section (2) and the grinding surface (3a) of the finish grinding section (3)
) is the il11 line (la) of the base metal part (1), respectively.
It is set perpendicular to. In this case, the distance between the grinding surfaces (2a) and (3a) is about 8 gm.

Incidentally, the grindstone pieces Ql... are fixed to the supporting wall \6) using an adhesive.

Next, the grinding method of this example will be described using the workpiece (G) having the above structure.

First, as shown in FIGS. 3 and 4, the workpiece (G) is attached coaxially to the grindstone shaft (S) of the l-axis back grinding device t (M). Next, silicon (Si) H
CI) Wafer (W) G oxidized (8'Oz)
The wafer (a) is adsorbed and held coaxially with the rotation axis (self) of the vacuum Nayak 0 through the maintenance table (14) which is attached to the surface of the wafer (a).Next, as shown in Fig. 3, The axis fm (St) of the grinding wheel shaft (5) and the axis of the rotating shaft (self) (
Move the vacuum chuck 0 so that it matches lsa).

Then, the rotation axis 4 is rotated, for example, every minute. ! ;00 rotations. In addition, the grindstone shaft (S) is lowered in the direction of the arrow (or the rotating shaft cL!l1 is raised in the direction of the arrow αD) relative to the grindstone @(S) at 0 revolutions per minute, for example. Then, the wafer (W) held by the vacuum chuck α is loosely inserted into the recess (4) of the workpiece (G), and its back surface α′jJ is brought into contact with the rough grinding part (2). , the grinding begins. At this time, the grinding fluid (II) is supplied to the grinding area from the fluid supply hole (not shown) provided in the grinding wheel shaft (F) through the through hole (7).As a result, the wafer ( The back surface of W) is diamond ground by the rough grinding part (2) to remove the adhering oxidation.The grinding debris generated at this time is removed from the radial # (97... After the removal of the oxide film on the back side (14) is completed, the grinding wheel axis < S is turned to the arrow (I).
As shown in FIG. The vacuum grinder is moved so that one of the grindstone pieces ul... is positioned on the axis (15a) of the rotation axis (l!1).

As a result, as the grinding wheel shaft (8) rotates, the grinding wheel piece (I
It stutters that all of I... pass through the axis (l5a). Next, the whetstone shaft (8) is lowered (or rotated) in the direction of the arrow, relative to the rotating shaft Q'9 at, for example, 900 revolutions per minute and the whetstone shaft (S) at, for example, 400 revolutions per minute. 4) in the direction of arrow Uη.

Then, the workpiece held by the vacuum chuck αJ (
The blade contacts the finish grinding part (3) and finish grinding is opened.
I will be treated. At this time, the grinding liquid H is supplied from the nozzle Q1 to the part to be ground. As a result, the back surface u3 of the wafer (W) is finish-ground to the extent of Rmaxrp+ the grindstone. When this finish grinding is completed, the grinding wheel shaft (S) is raised in the same direction as the arrow (or the rotation axis α field is lowered in the four directions of the arrow), and the vacuum chuck α4
The afJ of the wafer (W) is released.

In this way, in this embodiment, one base metal part (one
), the rough grinding section (2) and the finish grinding section (3) are integrally provided, so that rough grinding and finish grinding can be performed on one workpiece (G). Therefore, the grinding wheel shaft (8
) As a result, the back grinder can be downsized and can be integrated in-line with the semiconductor process. Moreover, since the removal of oxidized Bx (stow) is performed using large-diameter diamond abrasive grains, and then final grinding is performed using small-diameter diamond abrasive grains, the wear of the abrasive grains is delayed. Since clogging becomes less likely, the life of the grinding wheel is significantly extended. Therefore, when applied to semiconductor processes, dramatic results can be achieved in terms of processing costs and processing efficiency.

In addition, in the above embodiment, the rough grinding part (2) I is
Link-shaped grooves (8) and radial grooves (9)... are provided, but it is assumed that two conditions are met: they include a section with a circumferential speed of 0, and they serve as guides for the grinding fluid. For example, grooves in the shape of a base mesh or a mesh may be provided. Furthermore, the roughly ground portion may not be directly attached to the X-shape, but may be formed at another location and then fastened with adhesive, screws, or the like. moreover,
The rough grinding part (2) may be a diamond grindstone using vitrified as a binder.Furthermore, the abrasive grains of the rough grinding part and the finish grinding part may be, for example, CBN (cubic boron nitride) =
Other superabrasives such as 8iaN4 (silicon nitride) may also be used. Furthermore, in the above embodiment, the surface grinding of a silicon wafer is exemplified, but the application is not limited to this, and the abrasive grains may be A-based, W-based,
C type etc. may be used.

〔Effect of the invention〕

In this invention, by integrally providing a rough grinding section and a finish grinding section in one base metal part, it is possible to perform rough grinding and finish grinding on one workpiece. As a result, it becomes possible to use a single grinding wheel axis, which makes it possible to downsize the grinding machine and to inline the automated process accordingly.

Furthermore, since the grinding process is carried out sequentially from rough grinding to finish grinding, the abrasive grains are less likely to wear out and are less prone to clogging, resulting in a longer life as a grindstone. Therefore, it greatly contributes to reducing machining costs and improving machining efficiency.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of a workpiece according to an embodiment of the present invention, and Fig. 2 is a bottom view of the same. @ Figures 3 and 4 are explanatory diagrams of a grinding method according to an embodiment of the present invention. (G)... Workpiece, (l)... Base metal part, (2)
...Rough grinding section. (3)...Final grinding section, (g)...Wafer (workpiece), α3...back surface (workpiece surface), (B)...vacuum chunk (holding means).

Claims (2)

[Claims] (1) a base metal portion that is rotationally driven around an axis; a rough grinding portion that is provided on the base metal portion and has a flat first grinding surface that is perpendicular to the axis; a finish grinding part that is coaxial with the gold and is provided in a cup shape surrounding the rough grinding part, and has a flat second grinding surface parallel to the first grinding surface; A grinding wheel, characterized in that the second grinding surface is provided at a position farther from the base metal than the first grinding surface. (2) a base metal part that is rotationally driven around a first axis;
A rough grinding part provided on the base metal part and having a flat first grinding surface perpendicular to the first axis, and a cup that is coaxial with the base metal and surrounding the rough grinding part. A second grinding surface is provided in the shape of a plane and has a finish grinding portion formed parallel to the first grinding surface, and the second grinding surface is parallel to the first grinding surface. In a grinding method for surface grinding a workpiece having a size such that the workpiece surface is loosely inserted into the finish grinding part using a grinding wheel provided at a position spaced apart from the base metal from the grinding surface of No. 1, a first step of holding the workpiece in a holding means rotationally driven around the second axis with the workpiece surface orthogonal to the second axis; The first grinding wheel is moved relative to the grinding wheel.
a second step of aligning the axis of the and the second axis; and after this second step, rotating the grinding wheel around the first axis and rotating the workpiece around the second axis. a third step of roughly grinding the workpiece surface with the first grinding surface by moving the workpiece relatively to the grinding wheel along the second axis while rotating; After the third step, a fourth step in which the workpiece is moved relative to the grinding wheel to make the second axis perpendicular to the second grinding surface; The second grinding process is performed by rotating the workpiece around the first axis and moving the workpiece along the second axis relative to the grinding wheel while rotating the workpiece around the second axis. A grinding method comprising: a fifth step of finish-grinding the surface to be machined using a working surface.