JPH08201303A - Sheet laminator for semiconductor wafer and manufacture of semiconductor wafer - Google Patents

Abstract

PURPOSE: To prevent wafer cracking when the back face of a wafer is machined by automatically identifying foreign matter on the surface of the wafer when a protective sheet is fitted on the surface of the semiconductor wafer. CONSTITUTION: A laser radiating detection section 3 is provided directly before a protective sheet 17 is fitted at a protective sheet lamination section 4, or a pressure sensor is provided on the surface of a laminating roller 18 used for increasing the adhesiveness between a wafer and the protective sheet 17 when the protective sheet 17 is fitted at a protective sheet fit section. Foreign matter causing wafer cracking are automatically identified when the back face of the wafer is machined, and the wasteful stagnation of a device as well as wafer cracking is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet laminator for a semiconductor wafer and a method for manufacturing a semiconductor wafer, and more particularly to a method for automatically identifying a foreign substance on the opposite surface of a semiconductor wafer before processing the back surface of the semiconductor wafer to damage the surface. The present invention relates to a sheet laminator provided with a means for preventing cracks and cracks and a manufacturing method.

[0002]

2. Description of the Related Art Referring to FIG. 6, which shows a typical conventional sheet laminator, this apparatus comprises a loader section 1 and an unloader section in which carriers 32 and 33 for accommodating semiconductor wafers are mounted on a main surface of a main body 30, respectively. The belt 2 for transporting the semiconductor wafer in a U-shape from the loader unit 1 to the unloader unit 5 is arranged. Also, on the main surface of the main body 30, the protective sheet bonding section 4 having the protective sheet rolls 16, 16 'wound with the protective sheet 17, the bonding roller 18, and a pair of pressing rollers 31.
Is provided. A fixing device and a driving device of the bonding section 4 are not shown.

A large number of semiconductor wafers having a desired circuit function formed on one main surface are housed in a carrier 32 at predetermined intervals so that the one main surface faces upward. When the carrier 32 is attached to the loader unit 1, the upper semiconductor wafers are sequentially transferred onto the conveyor belt 2. However, this controller is not shown because it is publicly known. The semiconductor wafer 34 transported while being placed on the transport belt 2 stops at the protection sheet bonding unit 4. Unused protective sheet 17 wound on roll 16 '
Has a double structure with an adhesive sheet on the lower surface that is lightly adhered so as to be in close contact with one main surface that is the upper surface of the semiconductor wafer 34, and a base sheet on the upper surface for winding this adhesive sheet so as not to adhere to each other. Eggplant This base sheet is wound up by a roll 16. The pair of pressing rollers 31 are necessary to set the protective sheet 17 at a distance directly above one main surface of the semiconductor wafer 34. Laminating roller 1
8 rotates by being slightly pressed by the base sheet on the upper surface of the protective sheet 17, whereby the upper surface of the semiconductor wafer 34 and the adhesive sheet are bonded. Next, the adhesive sheet is cut by a cutter (not shown) to separate the base sheet and the adhesive sheet. If a perforation is formed in the adhesive sheet in advance, the adhesive sheet is separated from the base along the perforation.

[0004] A semiconductor wafer 34 having an adhesive sheet adhered to one main surface is conveyed on the belt 2 and stored in another carrier 33 in such a manner that the semiconductor wafer 34 is successively superimposed. Not detailed. The carrier 33 in which a predetermined number of semiconductor wafers are stored is taken out from the unloader unit 5 and transferred to the next step as it is, or transferred to the next step after temporary storage.

In the next step, in order to polish the surface opposite to the one main surface to which the protective sheet 17 is adhered, that is, the back surface, one main surface of the semiconductor wafer is placed on a fixing table, and A mechanical stress is applied to the back side. At this time, since the protection sheet 17 is provided between the one main surface and the fixing base, even if stress is applied, no damage or breakage occurs on the one main surface, and abrasion or the like occurs even before and after handling. It is said that there is an advantage that no foreign matter adheres to the one main surface. When the processing of the back side is completed,
In order to remove dust generated during processing, the sheet is sent to a cleaning step, and the protective sheet is also mechanically or chemically peeled back and forth.

In FIG. 6, the case where the protective sheet 17 has a double structure has been described, but a protective sheet consisting of only an adhesive sheet without a base sheet may be used. In this case as well, the bonding operation is completed after being appropriately cut, but illustration is omitted here. Further, this sheet laminator is laid out so as to work in front of the main body 30 (toward the paper), and if there is no necessity, the mounting direction of the carriers 32 and 33 is set on the main surface. 9
If the structure is rotated by 0 °, there is no need to provide a direction changing means at right angles to the conveyor belt 2. Further, although there is a step on the main surface of the main body 30 and a concave portion is formed in the front part of the center,
In some cases, such a concave portion is not formed.

[0007]

In the above-described sheet laminator, an accident often occurs that the semiconductor wafer whose one main surface is protected is damaged during processing the back surface of the semiconductor wafer in the next step. Examining the semiconductor wafer that caused the breakage, it was found that the gap between the protective sheet and one main surface of the semiconductor wafer was 0.1 mm or more, especially 1.0 mm to 2.0 mm.
It has been found that there is a foreign substance of about mm, and the foreign substance generates a concentrated stress on the wafer due to a pressing force at the time of processing the back surface, thereby causing damage. And the protection sheet 17
The laminator that covers the semiconductor wafer has neither means for detecting such foreign matter nor means for removing the foreign matter, and therefore, it is clear that even the contaminated foreign matter is covered with the protective sheet. Was. In addition, it was clarified that a foreign matter of the order of μm did not cause a breakage accident.

Conventionally, an apparatus for identifying foreign matter on the main surface of a semiconductor wafer has been used as appropriate, but such an apparatus has a function of trying to identify finer foreign matter as the degree of integration is improved. It was also found that they are good at identifying dust of the order of 1 μm or less, and may not detect giant dust.

For example, as an apparatus for detecting a foreign substance on a main surface of a semiconductor wafer by a laser with reference to FIG. A laser 51 is irradiated on the surface 52 of the wafer to be inspected, and undulations 5 on or within the wafer
3, or a scattering 55 containing a P-polarized light component from the regular pattern 54 is obtained. These scatters are passed through a polarizing plate 56 to form a laser 57 having only a P-polarized component. The laser 57 is detected by the photoelectric conversion device 58, and the output via the threshold level setting device 59, the waveform shaping device 60, and the pulse counting device 61 is scattered by a data processing device 64 from a regular pattern, or on a wafer or Whether the scattering is due to a true defect or foreign matter on the wafer is identified, and only the scattering from the true defect or foreign matter on the wafer or in the wafer is output as a measurement number. The data before and after the identification is stored in the recording or storage device 62 and output.

Here, the data processing device 64 which determines the discontinuity of the relationship between the number of defects and foreign matter and the size not only increases the scale of the processing circuit by the extrapolation method, but also has a size of approximately 3 to 10 μm. It is difficult to apply the extrapolation method to foreign matters other than the foreign matter within the range, and it is difficult to detect foreign matter on the order of mm.

As another apparatus for detecting foreign matter by using a laser, Japanese Patent Application Laid-Open No. 3-128445 discloses a foreign matter detection apparatus of the order of μm, which is unsuitable for detecting a larger foreign matter. It has performance. That is,
This is because it is not necessary in this step to detect the microdust, which does not have a risk of damaging the wafer.

In view of the above knowledge and various problems, the present invention has the following problems. (1) Foreign substances of 0.1 mm or more, particularly about 1.0 mm to about 2.0 mm can be detected and removed. (2) Immediately before laminating the sheets of the sheet laminator,
Detect and remove foreign objects. (3) To prevent accidents such as breakage when processing the back surface of the semiconductor wafer.

(4) The means for detecting and removing foreign matter is of a simple structure, and is small enough to be mounted on a table of a sheet laminator. (5) Even if foreign matter cannot be removed by automatic removal means, relief can be provided. (6) To reduce unnecessary man-hours such as handling damage accidents. (7) To improve yield, improve productivity and reduce loss cost. (8) Try to automate as much as possible. (9) A layout that does not lower the original workability of the sheet laminator. (10) To be able to detect only a foreign substance having a size that would cause a wafer breakage accident in the next process. (11) A small foreign substance that does not cause a wafer breakage accident in the next process should not be detected. (12) The original laminating function should not be stopped or deteriorated when foreign matter is removed.

[0014]

The first structure of the present invention is as follows.
Before processing the back surface of the semiconductor wafer, in a sheet laminator of the semiconductor wafer for protecting a main surface of the wafer with a sheet, a foreign substance on the main surface is identified at a position immediately before the main surface of the wafer is covered with the sheet. A detecting means is provided.

In particular, the detecting means includes means for irradiating the main surface of the semiconductor wafer with a laser, and a reflected light detector for capturing scattered light of the laser irradiated by the means.

According to a second configuration of the present invention, in addition to the first configuration, the detection of the foreign matter by the detection means is used as a control input, and the semiconductor wafer in which the foreign matter is detected is moved to another position. It is characterized by comprising processing means for transferring and storing.

Further, the third structure of the present invention is characterized in that a removing means for removing the foreign matter is provided in the transfer path in the processing means.

According to a fourth aspect of the present invention, there is provided a sheet laminator for a semiconductor wafer having a bonding roller for pressing the sheet so that the sheet is brought into close contact with the main surface of the semiconductor wafer before processing the back surface of the semiconductor wafer. And a pressure sensor for detecting a pressure on the surface of the roller, and an identification unit for identifying whether or not the pressure value detected by the pressure sensor is equal to or greater than a predetermined value.

In addition to the fourth structure, the fifth structure of the present invention uses, as a control input, the fact that a pressure value equal to or higher than a predetermined value is obtained by the identifying means, and the corresponding semiconductor wafer is moved to another position. It is characterized in that it is provided with a processing means for transferring to and storing it.

A semiconductor wafer manufacturing method according to the present invention is characterized in that the semiconductor wafer manufacturing method includes a step of protecting a main surface of the semiconductor wafer with a sheet before processing the back surface of the semiconductor wafer. Immediately before, a step of inspecting whether or not a foreign substance having a size equal to or larger than a predetermined value is present on the main surface of the semiconductor wafer is provided.

[0021]

1 is a perspective view of a first embodiment of the present invention. Referring to FIG. 1, a sheet laminator for a semiconductor wafer according to this embodiment includes a laser beam on a conveyor belt 2 immediately before a protective sheet bonding section 4. A point provided with a laser detector 3 having an oscillator 8, a reflected light detector 13 for detecting reflected light of a laser 9, and a foreign matter detection controller 19; a second transport belt 6 branched from the first transport belt 2; Except for having an unloader unit 7 for mounting a carrier 41 for accommodating a rejected semiconductor wafer provided at the end, since it is common to the conventional example of FIG. 6, the description of the common parts will be omitted.

The laser detector 3 narrows the laser 9 from the laser oscillator 8 and scans it from diagonally above so as to be orthogonal to the moving direction of the conveyor belt 2 to obtain the semiconductor wafer 3
4 'is irradiated on one main surface. Since the conveyor belt 2 is moving at a predetermined speed with the semiconductor wafer 34 ′ placed thereon, the entire main surface of one of the main surfaces is eventually irradiated with the laser 9. The reflected light from the semiconductor wafer 34 'is captured by the reflected light detector 13, converted into an electric signal and amplified, and the foreign matter detection / controller 19 determines whether or not foreign matter is present. If no is detected, the process proceeds to the protection sheet bonding section 4 as it is. However, when foreign matter is detected, control is performed such that the second conveyor belt 6 is operated and housed in the carrier 41. The semiconductor wafer housed in the carrier 41 is taken out again, and the foreign matter is removed by using, for example, wind pressure, water pressure, a brush, or a combination thereof while checking it visually by an operator.

Alternatively, the carrier 41 may be pulled out of the unloader section 7 and mounted on the loader section 1 again without performing such an operation. In this case, not only the reliability by the re-inspection is improved, but also the foreign matter removing means is provided on the transport belt 6 as described later, so that the transport belt 6
It has the advantage that it is not transported up. still,
The transport belt 6 has a U-shape in the transport direction. However, if the unloader unit 7 may be provided behind the main body 40, a simple linear configuration is sufficient.

FIG. 2 showing the laser inspection section 3 of FIG. 1 in detail.
Referring to the side view of FIG. 1, on one main surface of a semiconductor wafer 10, an uneven surface of a pattern 11 composed of a surface such as an insulating film or a metal film required for a circuit function and adhesion of a foreign matter 12 to be removed are attached. There is a convex surface. Pattern 1
Although the step of the unevenness of No. 1 is at most 100 μm order, the size of the foreign matter 12 causing breakage in the subsequent process is 0.1 mm or more, especially m
It has a height on the order of m.

Referring to the characteristic diagram of FIG. 3 in which the intensity of the scattered light 48 generated when the laser 9 of the laser oscillator 8 irradiates the pattern 11 and the foreign matter 12 is shown with a scan width on the horizontal axis, The scattered light 15 from the pattern is larger than the scattered light 14 from the pattern, and by setting an intermediate intensity between them to a threshold level 49, both can be distinguished. For this purpose, the detection signal from the reflected light detector 13 may be applied to the other input of the comparison amplifier in which one input is set to the threshold level 49. Do not need.

In FIG. 2, the light receiving angle θ1 of the vertical plane of the reflected light detector 13 is the incident angle θ2 of the vertical plane of the laser 9.
Is preferably not the same as the angle difference between the two (θ1−θ
2) is ± 10 ° or more, more preferably ± 30 ° or more and ± 90
° or less.

The laser inspection section 3 described above has an advantage that the circuit configuration is extremely simple because it is sufficient to capture the giant dust among the foreign substances. Further, in this embodiment, since the laser inspection unit 3 is arranged on the belt 2 immediately before the protection sheet bonding unit 4, the semiconductor wafer 34 is arranged.
There is also an advantage that foreign matter is unlikely to adhere to the one main surface and the process of the laser inspection unit 3 can be passed any number of times until the foreign matter is removed.

In this embodiment, no foreign matter removing means is provided on the conveyor belt 6, but it is more preferable to provide foreign matter removing means in order to achieve automation. This foreign matter removing means may be one by blowing air from directly above, or by a fixed brush or a forced rotating brush. In addition to this, the carrier 41 may be pulled out, placed in another cleaning tank, and a semiconductor wafer in a stored state may be removed by water.

Here, it is not preferable to provide foreign matter removing means on the conveyor belt 2 for the following reasons. The first reason is that abrasion may rarely occur on the surface with a brush or the like during the removal of foreign matter, and the semiconductor wafer that does not need to be removed may be damaged instead. That is, the semiconductor wafer passing through the foreign matter removing means must be limited to the one to which foreign matter has adhered. The second reason is that if there is a foreign matter removing means on the conveying belt 2 which is a main route, the conveying force is reduced and the belt 2 is stopped at the time of maintenance and inspection of this means, so that detection by laser and This is because bonding and the like stop. Therefore, it is more preferable that the foreign matter removing unit is provided in a path from the conveyor belt 6 to the reloading to the loader unit 1 because the main path is not affected.

In this embodiment, the laser inspection section 3 is provided on the belt 2 immediately before the protective sheet bonding section 4, but may be provided on the belt 2 immediately after the protection sheet bonding section 4. May be provided. When the laser inspection unit 3 is provided at the position immediately after, even the foreign matter adhering to the protection sheet 17 can be detected, but it is necessary to peel off the protection sheet 17 in the removing operation. In this case,
A belt corresponding to the second transport belt 6 is provided so as to be branched from the first transport belt 2 between the bonding section 4 and the unloader section 5.

FIG. 4 shows a perspective view of a second embodiment of the present invention.
Referring to FIG. 2, the laminator is a laminating roller 18.
With foreign matter detection controller 1
6 except that the second conveyor belt 6 is provided between the protective sheet bonding section 4 and the unloader section 7, and that the unloader section 7 is on the left side. Since it is the same as the conventional example, the description of the common part will be omitted.

First, the semiconductor wafer on which the protection sheet is to be mounted is set on the loader unit 1 and the first transport belt 2
The wafer is sent to the protective sheet bonding section 4 and the protective sheet 17 is mounted on the main surface of the cylinder of the bonding roller 18 used to increase the adhesion between the semiconductor wafer 10 and the protective sheet 17. When the pressure sensor detects irregularities on one main surface of the semiconductor wafer 10 and the foreign matter detection / controller 19 detects a pressure equal to or higher than a certain value,
The wafer is sent to the carrier 60 of the unloader section 7 by the second transfer belt 6, and is sent to the unloader section 5 by the transfer belt 2 if there is no abnormality. The wafer in which the abnormality is detected is taken out of the carrier 60, the protective sheet is peeled off, and any foreign matter that can be removed is removed by washing with water or the like, returned to the loader unit 1, and mounted again.

Laminating roller 18 with pressure sensor
Referring to the cross-sectional view of FIG.
A large number of pressure sensors 20 are arranged in a grid on the surface of the cylinder, whereby the semiconductor wafer 10 and the protection sheet 17 are arranged.
If there is a foreign substance 12 interposed between and, a concentrated stress is applied to a specific pressure sensor 20. This roller 18 supports 65
Is rotatably fixed. On a plane without the foreign matter 12, the pressing force is averaged, and a large concentrated stress is not applied to a specific pressure sensor.

As the pressure sensor, quartz, Rochelle salt,
Ammonium phosphate, barium titanate and the like are used as the raw materials, and among them, Rochelle salt and barium titanate are particularly preferred. In the pressure sensor 20, the charges generated in proportion to the pressure are amplified at predetermined levels, and when a pressure level higher than a predetermined value is applied, a buzzer or the like issues an alarm and the foreign matter detection controller 19 The wafer 10 is transferred to the second transfer belt 6 and stored in the carrier 60.

Here, an integrated circuit for amplifying the signal from the pressure sensor 20 to a predetermined level, a battery for obtaining a necessary power supply voltage, and the like are built in the roller 18 and the signal amplified to a predetermined level or more. Or the alarm signal
It is taken out of the roller 18 through a known rotary sliding connector and applied to the foreign matter detection controller 19, as shown in FIG.
Then, it is not shown and omitted.

The semiconductor wafer 10 housed in the carrier 60 is taken out of the carrier 60 in order to remove the foreign matter 12, the protective sheet 17 is peeled off by hand, the foreign matter 12 is removed, and the semiconductor wafer 10 shown in FIG. Laminated. Alternatively, the protection sheet 17 is melted and removed by chemical means, the foreign matter 12 is removed, and the protection sheet 17 is again applied to the laminator shown in FIG.

In the first and second embodiments, when a foreign object is detected, a means for generating a warning sound such as a buzzer to notify the worker, a means for blinking a warning lamp to notify the worker, There is a means for inputting to the control system and transferring it in another case, and it is preferable to carry out these individually or appropriately in combination of at least two of them.

In the above-described first and second embodiments, a specific laminator has been described. However, regardless of the front surface or the back surface of the semiconductor wafer, at least the step of detecting foreign matter is performed immediately before the sheet is brought into close contact with the sheet. In addition, the addition of a step of automatically or manually removing foreign matter has a significant effect in preventing damage to the semiconductor wafer, improving the yield, and reducing the loss.

[0039]

As described above, according to the present invention, before processing the back surface of a semiconductor wafer, immediately before mounting a protective sheet so as to protect the wafer surface, foreign substances on the wafer surface that cause cracks in the wafer are removed. By identifying at least the irregularities on the wafer surface at an early stage and reliably preventing the wafer from cracking, it is possible to not only reduce the loss cost, but also to prevent unnecessary equipment stagnation due to the wafer cracking and to improve the productivity. And the effect of improving
Each of the above-mentioned problems is achieved.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a side view of a laser detector provided in the first embodiment.

FIG. 3 is a characteristic diagram showing a pattern obtained by a laser detector provided in the first embodiment and a state in which scattered light from a foreign substance is separated by a threshold.

FIG. 4 is a perspective view of a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a bonding roller unit provided with a pressure sensor on a surface provided in the second embodiment.

FIG. 6 is a perspective view showing a conventional sheet laminator.

FIG. 7 is a perspective view showing a conventional apparatus for identifying foreign matter by laser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Loader part 2, 6 Conveyor belt 3 Laser detection part 4 Protection sheet bonding part 5, 7 Unloader part 8 Laser oscillator 9, 51, 57 Laser 10, 34, 34 'Semiconductor wafer 11, 54 Pattern 12 Foreign matter 13 Reflection light detection Part 14 Scattered light from pattern 15 Scattered light from foreign matter 16, 16 ′ Protective sheet roll 17 Protective sheet 18 Laminating roller 19 Foreign matter detection / controller 20 Pressure sensor 31 Holding roller 32, 33, 41, 60 Carrier 40 Main body 48 Scattered light 49 Threshold level 52 Wafer main surface 53 Undulation 56 Polarizing plate 58 Photoelectric conversion device 59 Threshold level setting device 60 Waveform shaping device 61 Pulse counting device 62 Storage device 64 Data processing device 65 Support

Claims (7)

[Claims] 1. In a sheet laminator for a semiconductor wafer, which protects the main surface of a semiconductor wafer with a sheet before processing the back surface of the semiconductor wafer, the main surface is placed at a position immediately before the main surface of the wafer is covered with the sheet. A sheet laminator for a semiconductor wafer, which is provided with a detecting means for identifying the foreign matter. 2. The semiconductor according to claim 1, wherein said detecting means includes means for irradiating a laser to the main surface of said semiconductor wafer, and a reflected light detector for capturing scattered light of said laser irradiated by said means. Sheet laminator for wafers. 3. A processing means for receiving a foreign substance detected by the detecting means as a control input and transferring and storing the semiconductor wafer in which the foreign substance is detected to another position. A sheet laminator for a semiconductor wafer as described above. 4. The semiconductor wafer sheet laminator according to claim 3, further comprising a removing means for removing said foreign matter in a transfer path of said processing means. 5. A semiconductor laminator for a semiconductor wafer, comprising a laminating roller for pressing a sheet so as to bring the sheet into close contact with the main surface of the semiconductor wafer before processing the back surface of the semiconductor wafer. A sheet laminator for a semiconductor wafer, comprising: a pressure sensor for detecting pressure; and identification means for identifying whether a pressure value detected by the pressure sensor is equal to or greater than a predetermined value. 6. The processing means for moving the corresponding semiconductor wafer to another position and storing the semiconductor wafer as a control input when the pressure value of a predetermined value or more is obtained by the identifying means. 5. A sheet laminator for a semiconductor wafer according to item 5. 7. A method of manufacturing a semiconductor wafer, comprising a step of protecting a main surface of the semiconductor wafer with a sheet before processing the back surface of the semiconductor wafer, wherein the main surface of the semiconductor wafer is formed on the main surface of the semiconductor wafer immediately before the step. A method for manufacturing a semiconductor wafer, comprising a step of inspecting whether a foreign substance having a size equal to or larger than a predetermined value exists.