JP3514108B2 - Wrapping device and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to improve the flatness of a flat work piece such as a semiconductor wafer by improving the sag shape of the lap surface, particularly the outer peripheral portion of the wafer. The present invention relates to a wrapping device and method.

[0002]

2. Description of the Related Art Generally, a semiconductor silicon mirror surface wafer manufacturing method has been obtained by a slicing step of slicing a single crystal rod manufactured by a single crystal manufacturing apparatus to obtain a thin disk-shaped wafer, and the slicing step. A chamfering process for chamfering the peripheral edge of the wafer to prevent cracking and chipping of the wafer, a lapping process for lapping the chamfered wafer to flatten it, and removing the processing strain remaining on the chamfered and lapped wafer surface. It includes an etching process, a polishing process for finishing the surface of the etched wafer into a mirror surface, and a cleaning process for cleaning the polished wafer.

By the way, the purpose of the lapping process is to align sliced wafers to a predetermined thickness and at the same time obtain necessary shape accuracy such as flatness and parallelism. It is generally known that the wafer after lapping has the highest shape accuracy, and it is said that the shape of the final wafer is determined. Therefore, the shape accuracy in the lapping process is extremely important.

Conventionally, as a wrapping technique, three movements of a concentric circular lapping plate, a revolving movement of a circular workpiece holding metal fitting with respect to the apparatus body, and a circular movement of a circular workpiece holding metal fitting are combined. A wrapping device that performs lap by giving relative motion to the lap surface plate and the workpiece is known. This wrapping device has, for example, a configuration as shown in FIGS.

FIG. 13 is a schematic exploded explanatory view of the lapping device, FIG. 14 is a cross-sectional schematic explanatory view of the lapping device, and FIG.
5 is a schematic top view showing a state in which the upper lap surface plate of the lapping device is removed, FIG. 16 is a plan view showing a surface plate surface of the lower lap surface plate, and FIG. 17 is an end surface portion of the lower lap surface plate of FIG. 18 is a plan view showing the surface plate surface of the upper lap surface plate.

In FIGS. 13 to 15, a lapping device 22 is a lower lap platen 2 provided so as to face each other in the vertical direction.
4 and an upper lap surface plate 26. The lower lap platen 24 and the upper lap platen 26 are rotated in opposite directions by a driving means (not shown).

The lower lap surface plate 24 has a sun gear 28 on the upper surface of its central portion, and an annular internal gear 30 is provided adjacent to the peripheral edge portion thereof.

Reference numeral 32 denotes a disk-shaped workpiece holding metal fitting (generally called a carrier), and a gear portion which meshes with the sun gear 28 and the internal gear 30 is formed on the outer peripheral surface thereof to form a gear structure as a whole. ing. The workpiece holder 32 has a plurality of receiving holes (carrier holes)
34 is provided. A workpiece W such as a wafer to be wrapped is placed in the receiving hole 34. Normally, a plurality of receiving holes (carrier holes) 34 are formed, but one receiving hole (carrier hole) 34 may be formed.

A workpiece holding metal fitting 32 is placed between the upper and lower lapping plates 26 and 24 and between a sun gear 28 located at the center of the lower lapping plate 24 and an internal gear 30 outside the lower lapping plate 24. The gears on the outer side of the work holding metal fitting 32 are engaged with each other to lower the upper lapping platen 26, and the work holding metal fitting 32 makes a planetary gear motion between the upper and lower lapping bases 26 and 24 which rotate while facing each other. The workpiece W is housed in a receiving hole 34 formed in the workpiece holder 32, and the workpiece holder 32 is rotated and revolved.

To carry out the lapping operation, a polishing liquid A such as aluminum oxide (Al ₂ O ₃ ) or silicon carbide (SiC), which is called a lapping slurry, and a liquid turbid liquid A, such as water containing a surface active agent, is applied to the nozzle 36. Flow through the through hole 38 provided in the upper lapping platen 26 into the gap between the upper and lower lapping plates 26 and 24, and feed the abrasive grains between the workpiece W and the upper and lower lapping plates 26 and 24 to form the upper and lower lapping plates. The shapes of the surface plates 26 and 24 are transferred to the workpiece W.

Here, in order to obtain the flatness, it is necessary to faithfully transfer the shapes of the upper and lower lapping plates 26 and 24 to the workpiece W, and the workpiece W and the upper and lower laps which are moving relative to each other. The movement of the lap slurry A between the surface plates 26 and 24 is a non-negligible existence.

This is because the abrasive grains in the lap slurry A are constantly worn and the grain size and sharpness change. This is because, if the movement of the lap slurry A is uneven, the portion to be processed by the abrasive grains having a smaller grain size and less sharpness than other portions will be immediately processed in a place where the flow of the lap slurry A is bad.

Therefore, the upper and lower lapping plates 26, 24 have surface plates 27, 25 at intervals of 20 mm to 50 mm in a grid-like manner, in which grooves 40 called "cutting" are dug to discharge unnecessary lapping slurry A and chips. (Figure 16-Figure 1
8).

On the other hand, with the rapid increase in the degree of integration of semiconductor devices, the flatness standard required for silicon wafers has become more strict. There is a limit to high flatness in polishing, and high flatness is also required for the etched wafer which is a raw material for polishing. As a highly flattening technique for etching, improvement of acid etching technique and adoption of alkali etching are in progress, but high flattening of lapping, which is a pre-step, is required.

The flatness by the current lapping is GBI.
R = 0.6 μm (GBIR: difference between maximum value and minimum value of thickness in flatness application region of wafer), SBIRmax = 0.
It is about 4 μm (SBIR: difference between maximum thickness and minimum thickness when measured for each site with the back surface of the wafer corrected), and further improvement is required. As the cause of deteriorating the shape, the sagging shape of the wafer outer periphery is dominant,
By improving this, it becomes possible to manufacture a high flatness wafer. However, the cause of the occurrence of the sagging shape on the outer peripheral portion of the wafer has not yet been identified.

[0016]

DISCLOSURE OF THE INVENTION The present inventor has paid attention to the slits on the lapping plate for the cause of the outer peripheral sag of the wafer, and has continued research on the relationship between the shape of the slits and the outer peripheral sag of the wafer. However, the outer peripheral portion of the wafer is easily slipped by the edge of the grooving groove of the lapping plate and the flow of the lapping slurry is concentrated in the innermost peripheral portion and the outermost peripheral portion of the lapping plate so that the amount of abrasive grains in the slurry due to retention is It was investigated that the peripheral sag of the wafer occurs due to the increase. The present inventor further conducted research and found that the sagging shape of the outer peripheral portion of the wafer was improved by forming the cut grooves of the lapping plate into a predetermined shape, and completed the present invention.

The present invention aims to improve the flatness of a flat work piece such as a semiconductor wafer by improving the wrapping surface of the work piece, particularly the outer peripheral portion of the wafer. The purpose is to provide.

[0018]

In order to solve the above problems, the first aspect of the lapping apparatus of the present invention is that the upper and lower lapping plates are rotatably sandwiched between the upper and lower lapping plates. A disk-shaped workpiece holding metal fitting having one or a plurality of receiving holes formed therein, a flat plate-shaped workpiece being arranged in the receiving hole, and the workpiece being held by the workpiece In a lapping device for performing a lap while moving relative to the upper and lower lap surface plates together with a metal fitting, only a middle portion of the surface plate surface of the upper and lower lap surface plates except for the innermost peripheral portion and the outermost peripheral portion And a lap slurry discharge port communicating with the cut groove of the lower lap platen is provided on the outer surface of the lower lap platen.

When the upper and lower lap surface plates are machined into the grooving surfaces of the surface plates facing each other, only the intermediate portion except the innermost peripheral portion and the outermost peripheral portion is machined to form the grooving groove in the intermediate portion. A kerf can be provided.

A second aspect of the lapping apparatus of the present invention is
The upper and lower lap platens and a disc-shaped workpiece holding metal fitting rotatably sandwiched between the upper and lower lap platens and having one or a plurality of receiving holes formed therein. In the lapping device for arranging a flat plate-shaped workpiece in a hole and performing relative lap of the workpiece together with the workpiece holding metal fitting with respect to the upper and lower lap surface plates, the above-mentioned upper and lower lap surface plates are provided. Of the surface plate surface of the upper and lower lap surface plates is filled with resin and the upper and lower lap surface plates are filled with resin to the groove grooves of the lower lap surface plate. A communicating lap slurry discharge port is provided on the outer surface of the lower lap platen.

A third aspect of the lapping apparatus of the present invention is
The upper and lower lap platens and a disc-shaped workpiece holding metal fitting rotatably sandwiched between the upper and lower lap platens and having one or a plurality of receiving holes formed therein. In the lapping device for arranging a flat plate-shaped workpiece in a hole and performing relative lap of the workpiece together with the workpiece holding metal fitting with respect to the upper and lower lap surface plates, the above-mentioned upper and lower lap surface plates are provided. The entire surface of the surface plate surface is subjected to a grooving process, and the upper and lower lap surface plates are provided with rounded corners of the innermost peripheral portion and the outermost peripheral surface of the surface plate surface.

The wrapping method of the present invention is the above-mentioned first method.
-The lapping apparatus of the third aspect is used to lap a flat plate-like workpiece to improve the flatness of the lap surface.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the present invention will be described below with reference to FIGS.

The basic structure of the device of the present invention is shown in FIGS.
Since there is no difference from the conventional lapping apparatus shown in FIG. 8, a re-explanation of its configuration will be avoided, and only the characteristic points of the present invention will be explained.

FIG. 1 is a plan view of an example of the surface plate surface of a lower lap surface plate used in the lapping apparatus of the present invention, FIG. 2 is a partially cutaway perspective view of the end surface portion of the lower lap surface plate of FIG. 1, and FIG. FIG. 4 is a plan view of an example of a surface plate surface of an upper lap surface plate used in the lapping apparatus of the invention, and FIG. 4 is a partial side view of the lower lap surface plate showing the cut groove portion of FIG. 1. 5 is a plan view of another example of the surface plate surface of the lower lap surface plate used in the lapping apparatus of the present invention, FIG. 6 is a partial perspective view of the end surface portion of the lower lap surface plate of FIG. 5, and FIG. FIG. 8 is a plan view of another example of the surface plate surface of the upper lap surface plate used in the lapping device of FIG. 8, FIG. 8 is a partial side view of the lower lap surface plate showing the cut groove portion of FIG. 5, and FIG. 9 is the lapping device of the present invention. 10 is a plan view of another example of the surface plate surface of the lower lap surface plate used in FIG. 10, FIG. 10 is a partial perspective view of the end surface portion of the lower lap surface plate of FIG. 9, and FIG. 11 is an upper wrap used in the lapping apparatus of the present invention. FIG. 12 is a plan view of another example of the surface plate of the surface plate, and FIG. 12 is a partial side view of the lower lap surface plate showing the cut groove portion of FIG. 9. 1 to 12, the same or similar members as those in FIGS. 13 to 18 are denoted by the same reference numerals.

1 to 4, upper and lower lapping plates 2
Similar to the conventional structure, 6 and 24 have grid-shaped cut-out grooves 40 at intervals of 20 mm to 50 mm. As shown in FIGS. 1 to 3, the upper lap platen 26 and the lower lap platen 24 are different from the former except that a through hole 38 connecting to a nozzle 36 for supplying the lap slurry A is formed. And have a similar structure.

Only the intermediate portions 27c, 25c except the innermost peripheral portions 27a, 25a and the outermost peripheral portions 27b, 25b of the surface plates 27, 25 of the upper and lower lap surface plates 26, 24 used in the lapping apparatus of the present invention. A dividing groove 40 is provided.

Various modes can be applied to the mode in which the slits 40 are provided only in the intermediate portions 27c and 25c. For example, as shown in FIGS. 1 to 4, the slits 40 are provided only in the intermediate portions 25c. It is done by applying. in this case,
As shown in FIGS. 2 and 4, in order to prevent unnecessary lap slurry A and chips from clogging the cutting grooves 40, the lap slurry discharge port 42 communicating with the cutting grooves 40 is formed on the outer surface of the lower lap surface plate 24. It is necessary to open the hole.

Since the lap slurry A flows down,
It does not make much sense to open the lap slurry discharge port on the upper lap platen 26 similar to the lower lap platen 24. But,
It is possible to adopt a configuration in which a slurry discharge port is provided near the surface of the upper lapping platen 26 (on the opening portion side, not the bottom of the dividing groove 40) to help discharge the lapping slurry and chips.

Further, as shown in FIGS.
By cutting the grooves 40 on the entire surface of 7, 25 and filling the grooves 40a and 40b of the innermost peripheral portions 27a and 25a and the outermost peripheral portions 27b and 25b with the resin B, only the intermediate portions 27c and 25c are formed. The slit groove 40 can also be left.

In this case, as shown in FIG.
0a and 40b are filled only with the resin R, and the bottoms of the dividing grooves 40a and 40b are not filled with the resin B, but left as a space portion so that the lap slurry discharge port 42
Be able to act as.

As the resin B used to fill the dividing grooves 40, silicone resin, epoxy resin and the like are preferably used.

The width of the innermost peripheral portions 27a, 25a is preferably one square of the dividing groove 40, that is, 20 mm to 50 mm. The width of the outermost peripheral portions 27b and 25b is also preferably one square of the dividing groove 40, that is, 20 mm to 50 mm. It should be noted that the size of one cell of the dividing groove 40 is not fixed and, of course, changes according to the variation of the diameter of the surface plate.

With such a structure, the flow of the lap slurry A will be the innermost peripheral portion 2 of the surface plate surfaces 27, 25.
7a, 25a and the outermost peripheral portions 27b, 25b are not concentrated and uniformized over the entire surface so that the wafer outer peripheral sag does not occur.

Further, as in FIGS. 5 to 8, the surface plate surface 27,
The groove 25 is processed on the entire surface of 25, and the innermost peripheral portion 27
a, 25a and the outermost peripheral portions 27b, 25b of the slit grooves 4
As shown in FIG. 9 to FIG.
By providing the above, the sagging of the outer periphery of the wafer can be similarly prevented. With such a configuration, the innermost peripheral portion 2
7a, 25a and the outermost peripheral portions 27b, 25b at the edges of the dicing grooves 40a, 40b reduce the deviation of the wafer, and the wafer is uniformly lapped evenly and no peripheral sagging occurs.

According to the lapping method of the present invention, by using the above-mentioned lapping apparatus, it is possible to achieve the lapping with high flatness without the peripheral sagging of the wafer.

[0037]

EXAMPLES The lapping method of the present invention will be described in more detail with reference to the following examples.

(Example 1 and Comparative Example 1) Workpiece (sample wafer): CZ, p-type, crystal orientation <1
00>, 200 mmφ, sliced silicon wafer polishing agent: aluminum oxide (Al ₂ O ₃ # 1200) Slurry supply amount: 800 cc / min Lapping load: 100 g / cm ² Lapping time: 15 minutes

Under the lapping conditions described above, the upper and lower lapping plates 26 and 24 shown in FIGS. 5 to 8 (the innermost peripheral portion and the outermost peripheral portion of the surface plate are filled with the silicone resin 40, and then the carrier is used. A lapping apparatus (Example 1) having a surface of resin filled by performing a lapping operation only with a carrier without inserting a wafer into the wafer (Example 1) and the cut grooves on the entire surface shown in FIGS. 16 to 18. Using the conventional apparatus (Comparative Example 1) having the upper and lower lapping plates 26 and 24 for processing, sample wafers (slice wafers that have been chamfered) 20 each are lapped, and the flatness (SBIR) of the lap surface is measured. The measurement was performed, and the results are shown in FIG. 19 (Example 1) and FIG. 20 (Comparative Example 1).

The flatness of the wafer lapped by the apparatus of the present invention (Example 1) is much higher than the flatness of the wafer lapped by the conventional apparatus (Comparative Example 1). It was found that the sagging shape was not generated in the outer peripheral portion, whereas the sagging shape was generated in the outer peripheral portion of the wafer in the latter.

The processing speeds of Example 1 and Comparative Example 1 were 7.04 μm / min for the former and 7.26 μm / m for the latter.
It was also confirmed that even if the upper and lower surface plates in which the portions having no slits were formed on the inner and outer peripheral portions were used, the processing speed did not decrease and the productivity did not decrease. In addition, Example 1 and Comparative Example 1
The scratch occurrence rate was 0.9%, which was the same as that of 0.9%, and it was found that no scratches were caused by the resin even when the cut grooves were filled with the resin.

(Example 2 and Comparative Example 2) The upper and lower lap surface plates 26, 24 shown in FIGS. 1 to 4 (without forming the cut grooves in the innermost peripheral portion and the outermost peripheral portion of the surface plate surface) ) And a conventional device (Comparative Example 2) having the lapping plates 26 and 24 shown in FIGS. 16 to 18 (Comparative Example 2). The sample wafer was lapped at, the SBIRmax of each was measured in order to compare the flatness of the lap surface, and each bird's-eye view was created. SBIRm of Example 2
ax = 0.43 μm, SBIRmax = 0.
It was 25 μm. In addition, each bird's-eye view is shown in Fig. 21.
This is shown in (Example 2) and FIG. 22 (Comparative Example 2). SBI
As is clear from the comparison of the measured value of Rmax and FIGS. 21 and 22, it can be seen that the flatness of the wafer wrapped according to Example 2 is significantly better than that of Comparative Example 2.

(Example 3 and Comparative Example 3) The upper and lower lap surface plates 26 and 24 shown in FIGS. 9 to 12 (the inner corner portion and the outermost peripheral portion of the surface plate are rounded at the opening corner portions of the cutting grooves). Lapping apparatus (third embodiment) and FIG.
Sample wafers were lapped under the same lapping conditions as in Example 1 and Comparative Example 1 using the conventional apparatus (Comparative Example 3) having the lapping plates 26 and 24 shown in FIGS. Each SBIRmax to compare
Was measured and a bird's-eye view of each was created. Example 3
SBIRmax = 0.44 μm, SBIR of Comparative Example 3
max = 0.20 μm. In addition, respective bird's-eye views are shown in FIG. 23 (Example 3) and FIG. 24 (Comparative Example 3). As is clear from the comparison of the measured value of SBIRmax and FIGS. 23 and 24, it can be seen that the flatness of the wafer wrapped according to Example 3 is significantly better than that of Comparative Example 3.

[0044]

As described above, according to the present invention, the flatness is improved by improving the sagging shape of the flat plate-like work piece such as a semiconductor wafer, particularly the peripheral portion of the wafer. The great effect that it becomes possible is achieved.

[Brief description of drawings]

FIG. 1 is a plan view of an example of a surface plate surface of a lower lap surface plate used in a lapping apparatus of the present invention.

2 is a partial perspective view of an end surface portion of the lower lap surface plate of FIG. 1. FIG.

FIG. 3 is a plan view of an example of a surface plate surface of an upper lap surface plate used in the lapping apparatus of the present invention.

FIG. 4 is a partial side view of a lower lap surface plate showing a cut groove portion of FIG. 1.

FIG. 5 is a plan view of another example of the surface plate surface of the lower lap surface plate used in the lapping apparatus of the present invention.

FIG. 6 is a partial perspective view of an end surface portion of the lower lap surface plate of FIG.

FIG. 7 is a plan view of another example of the surface plate surface of the upper lap surface plate used in the lapping apparatus of the present invention.

FIG. 8 is a partial side view of the lower lap surface plate showing the cut groove portion of FIG. 4;

FIG. 9 is a plan view of another example of the surface plate surface of the lower lap surface plate used in the lapping apparatus of the present invention.

10 is a partial perspective view of an end surface portion of the lower lap surface plate of FIG.

FIG. 11 is a plan view of another example of the surface plate surface of the upper lap surface plate used in the lapping apparatus of the present invention.

12 is a partial side view of the lower lap surface plate showing the cut groove portion of FIG. 7. FIG.

FIG. 13 is an exploded perspective view of the lapping device.

FIG. 14 is a cross-sectional explanatory view of a lapping device.

FIG. 15 is an explanatory top view showing a state in which the upper surface plate of the lapping device is removed.

FIG. 16 is a plan view of an example of a surface plate surface of a lower lap surface plate used in a conventional lapping apparatus.

FIG. 17 is a partial perspective view of an end surface portion of the surface plate of the lower wrap shown in FIG.

FIG. 18 is a plan view of an example of a surface plate surface of an upper lap surface plate used in a conventional lapping apparatus.

FIG. 19 is a graph showing the surface flatness (SBIR) of the wafer wrapped in Example 1.

FIG. 20 is a graph showing the surface flatness (SBIR) of the wafer wrapped in Comparative Example 1.

FIG. 21 is a view showing a bird's-eye view of the surface of the wafer wrapped in Example 2;

22 is a drawing showing a bird's-eye view of the surface of a wafer that has been wrapped in Comparative Example 2. FIG.

FIG. 23 is a drawing showing a bird's-eye view of the surface of the wafer wrapped in Example 3;

FIG. 24 is a drawing showing a bird's-eye view of the surface of the wafer wrapped in Comparative Example 3.

[Explanation of symbols]

22: lapping device, 24: lower surface plate, 26: upper surface plate,
25 and 27: surface plate, 25a and 27a: innermost peripheral portion, 2
5b, 27b: outermost peripheral portion, 25c, 27c: intermediate portion, 28: sun gear, 30: internal gear, 32:
Workpiece holding metal fitting, 34: receiving hole, 36: nozzle, 3
8: Through hole, 40, 40a, 40b: Cut groove, 42:
Lap slurry outlet, A: slurry, B: resin, W:
Workpiece.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Laid-Open No. 53-124964 (JP, A) Actual development No. 49-141496 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B24B 37/04 H01L 21/304 621

Claims (5)

(57) [Claims] 1. An upper and lower lap platens and a disc-shaped workpiece holding metal fitting rotatably sandwiched between the upper and lower lap platens and having one or a plurality of receiving holes. In the lapping apparatus, which has a flat plate-shaped workpiece arranged in the receiving hole, and performs the lap while moving the workpiece together with the workpiece-holding metal fitting with respect to the upper and lower lap surface plates, The upper and lower lap surface plates are provided with a slit groove only in an intermediate portion of the surface plate surface excluding the innermost peripheral portion and the outermost peripheral portion thereof, and the lap slurry discharge port communicating with the slit groove of the lower lap surface plate is the lower lap plate. A lapping device that is provided on the outer surface of the surface plate. 2. When the upper and lower lap surface plates are machined into the grooving surfaces of the surface plates facing each other, only the intermediate portion excluding the innermost peripheral portion and the outermost peripheral portion is subjected to the grooving groove processing. The lapping device according to claim 1. 3. An upper and lower lap surface plate and a disk-shaped workpiece holding metal fitting rotatably sandwiched between the upper and lower lap surface plates and having one or a plurality of receiving holes formed therein. In the lapping apparatus, which has a flat plate-shaped workpiece arranged in the receiving hole, and performs the lap while moving the workpiece together with the workpiece-holding metal fitting with respect to the upper and lower lap surface plates, The upper and lower lapping platens are machined on the entire surface of the lapping plate, and the upper and lower lapping plates are filled with a resin to fill the innermost and outermost circumferential lapping plates of the lapping plate. The lapping device is characterized in that a lap slurry discharge port communicating with the cut groove is provided on the outer surface of the lower lap platen. 4. An upper and lower lap platens and a disk-shaped workpiece holding metal fitting rotatably sandwiched between the upper and lower lap platens and having one or a plurality of receiving holes. In the lapping apparatus, which has a flat plate-shaped workpiece arranged in the receiving hole, and performs the lap while moving the workpiece together with the workpiece-holding metal fitting with respect to the upper and lower lap surface plates, The upper and lower lapping platens are provided with grooving on the entire surface of the lapping plate, and rounded portions are provided at the opening corners of the cutting grooves in the innermost peripheral portion and the outermost peripheral portion of the upper and lower lapping platens. Lapping device characterized by. 5. A lapping process, wherein a flat work piece is lapped using the apparatus according to any one of claims 1 to 4 to improve the flatness of the lap surface. Method.