JPH0917842A - Method of detecting dislocation of semiconductor wafer - Google Patents

Abstract

PURPOSE: To surely detect the dislocation of a wafer, and enable the breakdown of a wafer in after process to be prevented, and besides, to enable the device to be operated stably by placing a wafer between a light emitting part and a light receiving part, and detecting the dislocation of the wafer with the value of amount of light reception to the amount of light emission of detection light. CONSTITUTION: Semiconductor wafers W are placed between light emitting parts 14a and 14b such that one main surface of each semiconductor wafer W having two main surfaces is directed toward the light emitting parts 14a and 14b of a sensor, which has light emitting parts 14a and 14b and light receiving parts 15a and 15b, and that the other face of each semiconductor wafer W is directed toward the light emitting parts 15a and 15b. Next, detection light 16 in line form or plane form at a projection face is emitted from the light emitting parts 14a and 14b to the light receiving parts 15a and 15b. And, the semiconductor wafer W is judged to be dislocated when the value of the luminous energy of the detection light 16 received with the light receiving parts 15a and 15b to the luminous energy of the detection light emitted from the light emitting parts 14a and 14b goes wide of the preset range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting deviation of a semiconductor wafer (hereinafter, wafer is omitted) in a manufacturing process of a semiconductor device.

[0002]

2. Description of the Related Art In a specific processing step of a semiconductor device manufacturing process, a wafer is rotated or tilted with reference to the orientation flat of the wafer. Will be needed. This orientation flat alignment is normally performed at once for all wafers in a state where a plurality of wafers, for example, 25 wafers are placed in the wafer cassette (1 cassette or 2 cassettes).

The orientation flat alignment is performed as follows, for example. A roller is placed in the bottom opening area of the wafer cassette having an opening in the bottom. At this time, the arc portion of the wafer (the portion other than the orientation flat) contacts the roller in the opening region. When the roller is rotated in this state, the wafer rotates together with the rotation of the roller while the arc portion and the roller are in contact with each other. Then, when the wafer rotates and the orientation flat comes to the position of the roller,
Since the roller is separated from the wafer, the wafer does not rotate.

In this way, sensing is performed in a state where all the wafers have stopped rotating. In the sensing, as shown in FIG. 3, the detection light 31 is located below the orientation flat 32 of the wafer A and near the boundary between the orientation flat 32 and the arc portion 33.
When the wafer intercepts this detection light 31,
It is determined that the wafer is misaligned. In this way, when it is determined that the wafer is displaced, the orientation flat alignment is performed again, or the apparatus is stopped in some cases.

[0005]

However, since the detection light 31 is a spot and only the orientation flat 32 side is detected in the above-described method for detecting the deviation of the wafer, the position is misaligned as in the wafer B shown in FIG. However, since the wafer B does not block the detection light 31, it is not determined that the position is displaced. If this wafer B is sent to the subsequent process in this state, the wafer may be damaged in the subsequent process.

Further, even if the positional deviation is within an allowable range, the sensor may determine that the positional deviation has occurred, and the apparatus may stop.

The present invention has been made in view of the above points, and provides a method capable of reliably detecting a wafer shift, preventing a wafer from being damaged in a post-process, and stably operating the apparatus. The purpose is to do.

[0008]

The present invention provides two means.
One of the main surfaces of a wafer having two main surfaces is directed to the light emitting section of a sensor having a light emitting section and a light receiving section, and the other main surface of the wafer is directed to the light receiving section. The step of placing the wafer between the light receiving section and the step of emitting linear or planar detection light from the light emitting section toward the light receiving section on the projection surface is emitted from the light emitting section. When the value of the light amount of the detected light received by the light receiving unit with respect to the detected light amount of the detected light is out of a preset range, it is determined that the wafer is displaced. A deviation detection method is provided.

Here, as the light emitting portion (light source) of the detection light, a semiconductor laser having a wavelength of 700 to 1300 nm (visible light region), a laser having various wavelengths having energy that does not damage the semiconductor wafer, and the like are used. be able to.

As the light receiving section, a light receiving element such as CCD (charge coupled device) can be used. The light emitting unit may include means such as a light projecting lens for forming the linear or planar detection light, and the light receiving unit for condensing the linear or planar detection light. Means such as a condenser lens may be provided.

As a method of placing the wafer between the light emitting portion and the light receiving portion, a method of placing a wafer cassette in which a plurality of wafers are stood vertically and accommodated between the light emitting portion and the light receiving portion, etc. Can be mentioned. Even if the wafer cassette is not mounted between the light emitting unit and the light receiving unit, the semiconductor wafer can be irradiated with the detection light emitted from the light emitting unit by using a mirror body or the like so that the light receiving unit can receive the detection light. It just needs to be arranged.

According to the method of the present invention, the linear or planar detection light is used, and the positional deviation of the wafer is quantitatively measured by the value of the amount of received light with respect to the amount of emitted light. The positional deviation of the wafer can be detected reliably and accurately.

Further, if the value of the amount of received light with respect to the amount of emitted light is within a certain range, it is not judged as a positional deviation. Therefore, if the positional deviation is within an allowable range, the operation can be continued without stopping the device, The work can be optimized.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic view for explaining the wafer deviation detecting method of the present invention. Further, FIG. 2 is a diagram for explaining a detection range in the wafer deviation detection method of the present invention. Reference numeral 11 in the drawing denotes a wafer cassette. The wafer cassette 11 has a box shape having a plurality of grooves, has a flange portion 11a at the top, and an opening 11 at the bottom.
b. A plurality of wafers W, for example, 25 wafers W are arranged side by side in the vertical direction along the groove of the wafer cassette 11. Further, the two wafer cassettes 11 can be integrally moved with their lower parts fitted in the openings of a pallet (not shown).

A roller 12 for aligning the orientation flat is arranged below the wafer cassette 11. The roller 12 can be rotated by a driving means 13. Further, the roller 12 and the driving means 13 are configured to be able to integrally move up and down by an elevating means (not shown) (in the direction of the arrow in FIG. 1).

Further, the wafer cassette 1 is used for sensing.
1, the light emitting portions 14a and 14b and the light receiving portions 15a and 15b of the sensor are arranged so as to sandwich 1. That is, in the wafer cassette 11, one main surface of the wafer faces the light emitting units 14a and 14b, and the other main surface of the wafer faces the light receiving units 15a and 15b.
It is located between 4a, 14b and the light receiving parts 15a, 15b. The light receiving portions 15a and 15b are electrically connected to control means (not shown).

Next, the procedure of the wafer deviation detecting method of the present invention will be described.

The flange portion 11a of the wafer cassette 11 is supported by a pallet (not shown) and is moved to a predetermined position for aligning the orientation flat. Next, the roller 12 and the driving means 13 are integrally lifted by a not-shown elevating means until the roller 12 contacts the arc portion 18 of the wafer W exposed from the opening 11b of the wafer cassette 11.

Next, the roller 12 is rotated by the driving means 13 to perform orientation flat alignment. Specifically, when the roller 12 is rotated, the wafer W rotates together with the rotation of the roller 12 while the arc portion 18 and the roller 12 are in contact with each other, and the orientation flat 1 is positioned at the position of the roller 12.
When 7 comes, that is, orientation flat 1
When 7 is directed downward and becomes substantially horizontal, the roller 12 and the wafer W are separated from each other and the wafer W does not rotate. In this way, the orientation flat alignment is completed when all the wafers W in the wafer cassette have stopped rotating. Normally, the orientation flat alignment time is set in consideration of the number of wafers W, etc.
It is controlled by adjusting the rotation time of 2.

Then, the roller 12 and the driving means 13 are integrally lowered by the elevating means, and the pallet is raised to reach a position between the light emitting portions 14a, 14b and the light receiving portions 15a, 15b of the sensor. 11
To rise. Then, in this state, the positional deviation of the wafer is sensed.

In sensing, for example, a wavelength of 700
nm semiconductor laser as a light source, the light emitting unit 14 of the sensor
The linear detection light 16 from a and 14b is received by the light receiving portions 15a and 15a.
Emit toward b. At this time, the linear detection light 16 is
The light is received by the light receiving portions 15a and 15b while being blocked by the wafer W. Therefore, the area in which the wafer W is present can be determined by the amount of emitted detection light 16 and the amount of received detection light 16. That is, by associating the amount of light with the distance of the wafer W that blocks the detection light in advance, it is possible to know whether or not the wafer W is accurately placed.

By utilizing this, a permissible range of positional deviation of the wafer W is set in advance, and when the value of the amount of received light with respect to the amount of emitted light deviates from the permissible range, it is determined that the positional deviation of the wafer W has occurred. be able to. For example, in the case of an 8-inch wafer, the allowable range of positional deviation is 1.0 to 5.
By setting it to 0 mm and assuming that the wafer positional deviation has occurred when exceeding this range, it is possible to accurately detect the wafer positional deviation.

By doing so, the detection area for the wafer is widened, and the positional deviation of the wafer can be detected reliably and accurately. Therefore, it is determined that the wafer A shown in FIG. 2 has no positional deviation and the wafer B has a positional deviation.

In this way, when the wafer position deviation is detected, the orientation flat adjustment is performed again, or in some cases, an alarm is sounded to stop the operation.

In the conventional semiconductor device manufacturing process, in the conventional method of detecting the positional deviation of the wafer by using the spot-shaped detection light, the positional deviation of the wafer is accurately detected once or twice a month. However, there is an accident in which a misaligned wafer is damaged during transportation. As a result, it has been necessary to stop the operation for a long time because it takes a lot of time to clean the portion where the accident has occurred and to clean the filter. On the other hand, in the method of the present invention for detecting the positional deviation of the wafer using linear or planar detection light, there is no damage to the wafer due to the omission of the positional deviation of the wafer,
It was able to operate satisfactorily.

In the above embodiment, the linear detection light is used as the detection light. However, in the present invention, even if the plane detection light is used as the detection light, the wafer can be similarly accurately measured. Can be detected.

Further, in the above embodiment, the positional deviation is detected for all the areas of the wafer to which the linear detection light is irradiated. However, the linear detection light is divided into a plurality of pieces and the detection light is divided. The position deviation may be detected for the portions irradiated with (for example, two locations near the orientation flat and two locations in the upper arc portion).

[0029]

As described above, according to the wafer deviation detecting method of the present invention, the wafer is placed between the light emitting portion and the light receiving portion of the sensor, and the wafer is linearly projected from the light emitting portion toward the light receiving portion. Or, when a planar detection light is emitted and the value of the light amount of the detection light received by the light receiving unit with respect to the light amount of the detection light emitted from the light emitting unit is out of the preset range,
Since it is judged that the wafer is displaced, the displacement of the wafer can be reliably detected, the damage of the wafer in the subsequent process can be prevented, and the apparatus can be stably operated.
As a result, the yield in the wafer processing process can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a wafer shift detection method of the present invention.

FIG. 2 is a diagram for explaining a detection range in the wafer deviation detection method of the present invention.

FIG. 3 is a diagram for explaining a detection range in a conventional wafer shift detection method.

[Explanation of symbols]

11 ... Wafer cassette, 11a ... Flange portion, 11b ...
Opening portion, 12 ... Roller, 13 ... Driving means, 14a, 14
b ... light emitting part, 15a, 15b ... light receiving part, 16 ... detection light,
17 ... Orientation flat, 18 ... Arc part.

Claims (1)

[Claims] 1. A main surface of a semiconductor wafer having two main surfaces is directed to the light emitting section of a sensor having a light emitting section and a light receiving section, and the other main surface of the semiconductor wafer is directed to the light receiving section. And placing the semiconductor wafer between the light emitting unit and the light receiving unit, and emitting linear or planar detection light from the light emitting unit toward the light receiving unit on the projection surface. The position of the semiconductor wafer when the value of the light quantity of the detection light received by the light receiving section with respect to the light quantity of the detection light emitted from the light emitting section is out of a preset range. A semiconductor wafer misalignment detection method characterized by determining misalignment.