JP2001028355A - Polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing apparatus which detects the front and rear surfaces at a stage, before a wafer is placed on a chuck table and prevents polishing failures beforehand, when a workpiece such as a semiconductor wafer or the like is polished. SOLUTION: A protective tape is stuck on a surface (circuit surface) of a semiconductor wafer to be polished. Presence of this protective tape is detected by front/rear detecting means 5 disposed in carrying means to identify the front or rear surface of the semiconductor wafer. Therefore, even if the semiconductor wafer is housed incorrectly in a cassette of the front/rear directions, the wafer is carried correctly to a chuck table by checking the direction by the front/rearface detecting means 5. Thus, polishing of a surface side on which a circuit is formed can be prevented beforehand. As the front/rear detecting means 5, sensors detecting color, concentration, reflectance, hardness and the like can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding device for grinding a workpiece such as a semiconductor wafer.

[0002]

2. Description of the Related Art A semiconductor wafer having a plurality of circuits such as ICs formed on a surface thereof is used to improve heat dissipation or to use a card,
It is ground to a predetermined thickness to reduce the weight and size of a mobile phone or the like. This grinding is performed by attaching a protective tape to the surface of the semiconductor wafer, holding the protective tape on the chuck table of the grinding device by suction so that the protective tape side faces the lower surface, and grinding the exposed back surface of the semiconductor wafer with a grinding wheel. Will be performed.

[0003]

However, especially in a grinding apparatus that automatically unloads a semiconductor wafer from a cassette and automatically mounts the semiconductor wafer on a chuck table, the front and back of the semiconductor wafer are erroneously inverted and the semiconductor wafer is inserted into the cassette. May be contained. That is, normally, the protective tape side is housed in the cassette with the lower surface facing down, but some of them are erroneously housed with the protective tape side facing up. In such a case, a serious problem has been pointed out that the protective tape side is ground by a grinding wheel, and a circuit below the protective tape is broken, and an expensive semiconductor wafer becomes defective.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and even if a reversed work piece is erroneously stored in a cassette, the work piece is placed on the chuck table before the work piece is placed on the chuck table. It is an object of the present invention to provide a grinding apparatus capable of detecting at the stage of the above and preventing a grinding error from occurring.

[0005]

As technical means for achieving this object, the present invention provides a chuck table for holding a semiconductor wafer, grinding means for grinding the semiconductor wafer held on the chuck table, The grinding device includes at least front and back detection means for detecting the front and back of the semiconductor wafer, and the front and back are detected before the semiconductor wafer is placed on the chuck table. The outline of the grinding device is as follows. In this grinding apparatus, when the surface of the semiconductor wafer on which the circuit is formed is defined as the front surface, a protective tape is adhered to the surface and the surface comes into contact with the chuck table. Detecting the front and back, by detecting the front and back, a color detection sensor is provided in the front and back detection means, to detect the color of the protective tape or the color of the semiconductor wafer to detect the presence or absence of the protective tape, A hardness detection sensor is provided in the front and back detection means, and the presence or absence of the protection tape is detected by detecting the hardness of the protection tape or the hardness of the semiconductor wafer,
The grinding device includes a cassette mounting area on which a cassette containing a semiconductor wafer is mounted, a first transfer unit that unloads the semiconductor wafer from the cassette in the cassette mounting area, and a transfer unit that transfers the semiconductor wafer by the first transfer unit. Centering means for centering the center of the obtained semiconductor wafer, second carrying means for carrying out the semiconductor wafer in the centering means and carrying it to the chuck table, and carrying out cleaning means for carrying out the ground semiconductor wafer in the chuck table A third transfer means for transferring the semiconductor wafer having been cleaned in the cleaning means, and a fourth transfer means for unloading the cleaned semiconductor wafer in the cleaning means, wherein any one of the first transfer means, the centering means, and the second transfer means The front and back detection means is provided at the middle or at any intermediate position, and the semiconductor wafer is unloaded from the cassette and placed on the chuck table. Detecting the front and back of the semiconductor wafer during the further the detection result of the front and rear detection means and error display if incorrect, it is an gist.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a grinding apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In FIG.
Reference numerals 1A and 1B denote cassettes mounted on the cassette mounting area of the grinding apparatus M, and the semiconductor wafer W as a workpiece.
Are stored. An unground semiconductor wafer is stored in the cassette 1A, and a ground semiconductor wafer is stored in the cassette 1B.

As shown in FIG. 2, a protective tape 2 is attached to a surface of a semiconductor wafer W on which a plurality of circuits such as ICs (not shown) are formed, and the protective tape 2 side is a lower surface. It is housed in 1A (same in 1B).

[0008] Reference numeral 3 denotes a first device provided in the concave portion of the grinding device M.
As shown in FIG. 3, the transfer means includes a vertically moving means 3a and a turning means 3b, and a folding / retractable reciprocating arm 3c is attached to the upper end of the turning means 3b. Is provided with a wafer holding unit 4.

The wafer holding part 4 is a substantially U-shaped plate-like body having a bifurcated tip, and is rotated about a horizontal axis with respect to a driving part 4a attached to the tip of the reciprocating arm 3c.
It can be inverted by 0 degrees. Further, on both sides of the branch portion, suction portions 4b for sucking the semiconductor wafer W are provided opposite to each other, and front and back detection means 5 are provided at a tip portion. In this case, the front and back detection means 5 is a color detection sensor, and can detect the color of the protective tape 2, for example, blue.

The first transfer means 3 unloads the semiconductor wafers contained in the cassette 1A one by one and transfers them to the center table 6b of the centering means 6. That is,
By moving the first transfer means 3, the wafer holding section 4 is inserted into the cassette 1A, and the lower surface side of the semiconductor wafer W to be carried out is sucked by the suction section 4b and carried out of the cassette 1A.

At this time, since the protective tape 2 is adhered to the lower surface of the semiconductor wafer W as described above, the color of the protective tape 2 can be detected by the front and back detection means 5 (color detection sensor). Thus, the front and back of the semiconductor wafer W are detected. That is, the front and back surfaces of the semiconductor wafer W can be detected based on the presence or absence of the protective tape 2.

Normally, the protective tape 2 is housed in the cassette 1A so that the protective tape 2 side faces the lower side. Therefore, when the protective tape 2 is not detected, it is improper (abnormal), and the semiconductor wafer is erroneously turned upside down. It can be seen from FIG.

When the detection result by the front and back detection means 5 is inappropriate (abnormal), the control panel 7 is activated by an alarm sound or the like.
Error display. Then, after being unloaded from the cassette 1A, the wafer holding unit 4 is turned 180 degrees while the semiconductor wafer W is being sucked, and the wafer holding unit 4 is transferred to the center table 6b of the centering means 6 while holding the inverted state. As a result, the semiconductor wafer W can be corrected to a normal state.

The outer peripheral edge of the semiconductor wafer W conveyed to the centering means 6 is pushed by a plurality of pins 6a moving in the centripetal direction, thereby performing centering. Thereafter, the sheet is sucked by the second transfer means 8 which is formed so as to be vertically movable and pivotable, and is transferred onto the chuck table 9 indexed to the receiving position P.

The semiconductor wafer W sucked and held on the chuck table 9 is exposed with the protective tape 2 side (front side) contacting the chuck table 9 and the back side facing upward. It is located in the means 11.

In the grinding means 11, first, the first grinding wheel 11a is positioned and rough grinding is performed. In this rough grinding, the first grinding wheel 11a and the chuck table 9 are rotated, and the back surface of the semiconductor wafer W exposed by the first grinding wheel 11a is ground. Next, the semiconductor wafer W is moved to the second grinding wheel 11b.
And finish grinding is performed. Also in this finish grinding, the second grinding wheel 11b and the chuck table 9 are rotated, and the back surface of the semiconductor wafer W is ground by the second grinding wheel 11b.

After finishing grinding, the turntable 10
The chuck table 9 is indexed to the transfer position Q by the rotation of. The ground semiconductor wafer on the chuck table 9 is sucked by the suction pad 12a of the third transfer means 12 (the same configuration as the second transfer means 8), carried out, and transferred to the cleaning means 13.

The ground semiconductor wafer conveyed to the cleaning means 13 is spin-cleaned and spin-dried. After the cleaning, the cleaned semiconductor wafer is carried out by the fourth transporting means 14 (also serving as the first transporting means 3) and stored in the cassette 1B. In this way, a series of grinding steps is completed, but this grinding step is repeatedly and continuously performed with a timing.

Here, some variations are conceivable, which will be described below. In the above-described embodiment, the unground semiconductor wafer is housed in the cassette 1A with the protective tape 2 side down, but it is also possible to house the cassette wafer 1A with the protective tape 2 side up. It is.

In this case, the front / back detection means 5 uses a sensor for detecting the color of the semiconductor wafer W. When the semiconductor wafer W is detected, the wafer holding section 4 is inverted after being carried out of the cassette 1A and the inverted state is held. And transported to the chuck table 9. As a result, the protective tape 2 comes into contact with the chuck table 9, and the back surface of the semiconductor wafer W is exposed as the upper surface.

On the other hand, when the semiconductor tape cannot be detected because the protective tape 2 side is erroneously turned down, it becomes improper (abnormal), and an error display accompanied by an alarm sound or the like is displayed on the control panel 7. At this time, after unloading from cassette 1A,
The wafer holding unit 4 is transported to the chuck table 9 without being inverted.

Even in this case, the front and back detection means 5
Can be implemented by a sensor that detects the color of the protective tape 2. In short, the structure may be such that the front and back detection means 5 can detect the front and back surfaces of the semiconductor wafer W.

The front / back detection means 5 is preferably attached to the wafer holding section 4 as described above, so that the front and back faces can be detected immediately when the wafer is unloaded from the cassette 1A. However, the unground semiconductor wafer is mounted on the chuck table 9 anyway. The mounting position is not limited to the wafer holding unit 4 since it is only necessary to be able to detect the front and back before being placed. For example, the front and back detection means 5 is provided in one of the centering means 6 and the second transport means 8 or provided in the middle of either of them, and the cassette 1
The front and back sides of the semiconductor wafer are detected before the semiconductor wafer is unloaded from A and placed on the chuck table 9.

Even if the semiconductor wafer W is erroneously turned upside down and housed in the cassette 1A, the semiconductor wafer W once carried out is returned to the cassette 1A in a proper state, and if the semiconductor wafer W is carried out again, the front and back sides are in a proper state. Semiconductor wafer can be transferred, and automatic correction can be performed without the intervention of an operator.

Further, the front / back detection means 5 is not limited to a color detection sensor, but may be implemented by a hardness detection sensor, for example. The hardness of the protective tape 2 or the hardness of the semiconductor wafer W is detected to detect the front and back of the semiconductor wafer.
In addition, a sensor that detects color density, light reflectance, and the like can be applied. Further, the place where the cassettes 1A and 1B are placed is not limited to the above-mentioned position, and may be placed at a position indicated by a virtual line in FIG. 1, and these can be appropriately selected.

[0026]

As described above, according to the grinding apparatus of the present invention, even if the front and back surfaces of the semiconductor wafer are erroneously inverted and housed in the cassette, the front surface of the semiconductor wafer (the protective tape is The expensive semiconductor wafer is not damaged by grinding the pasted circuit surface). In particular,
If the front and back detection means are provided in the first transport means, it is possible to immediately determine whether the front and back are proper or inappropriate when the semiconductor wafer is carried out of the cassette, so that the response is prompt and the productivity is improved. Also, even if the semiconductor wafer is turned upside down and housed in the cassette, the semiconductor wafer once carried out is returned to the cassette in a proper state, and when the semiconductor wafer is carried out again, the semiconductor wafer having the proper front and back sides is transported. Automatic correction can be performed without the intervention of an operator, and productivity can be further improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a grinding device according to the present invention.

FIG. 2 is a perspective view of a semiconductor wafer to which a protective tape is attached.

FIG. 3 is a schematic perspective view showing a first transport unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A, 1B ... Cassette 2 ... Protective tape 3 ... First conveyance means 4 ... Wafer holding part 5 ... Front and back detection means 6 ... Centering means 7 ... Control panel 8 ... Second conveyance means 9 ... Chuck table 10 ... Turntable DESCRIPTION OF SYMBOLS 11 ... Grinding means 12 ... Third conveyance means 13 ... Cleaning means 14 ... Fourth conveyance means

Claims (6)

[Claims] 1. A grinding apparatus including at least a chuck table for holding a semiconductor wafer and grinding means for grinding the semiconductor wafer held on the chuck table, wherein the grinding apparatus includes front and back surfaces of the semiconductor wafer. And a front and back detecting means for detecting front and back, and detecting the front and back before the semiconductor wafer is placed on the chuck table. 2. A surface on which a circuit of a semiconductor wafer is formed is defined as a front surface, and a protective tape is adhered to the surface so that the surface comes into contact with the chuck table. The grinding apparatus according to claim 1, wherein the front and back sides are detected by detecting 裏. 3. The grinding apparatus according to claim 2, wherein a color detection sensor is provided in the front and back detection means, and detects the presence or absence of the protection tape by detecting the color of the protection tape or the color of the semiconductor wafer. 4. The grinding apparatus according to claim 2, wherein a hardness detection sensor is provided in the front and back detection means, and detects the presence or absence of the protection tape by detecting the hardness of the protection tape or the hardness of the semiconductor wafer. 5. A grinding apparatus, comprising: a cassette mounting area on which a cassette accommodating a semiconductor wafer is mounted; first transport means for unloading the semiconductor wafer from the cassette in the cassette mounting area; Centering means for aligning the center of the semiconductor wafer transferred by the transfer means, second transfer means for unloading the semiconductor wafer from the centering means and transferring it to the chuck table, and grinding the semiconductor wafer on the chuck table A third transporting means for transporting the semiconductor wafer to the cleaning means, and a fourth transporting means for transporting the cleaned semiconductor wafer in the cleaning means, wherein the first transporting means, the centering means, the second The front and back detection means is provided in any of the transfer means or provided in the middle of any one of them, and the semiconductor wafer is unloaded from the cassette and chucked. 5. The grinding apparatus according to claim 1, wherein the front and back of the semiconductor wafer are detected while being mounted on the table. 6. An error display if the result of detection by said front and back detection means is incorrect.
The grinding device as described.