JPH09252041A - Wafer transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable wafers to be transferred under optimal conditions by a pneumatic transfer device. SOLUTION: In this wafer transfer method, a transfer plate 61 where a gas feed path 62 is provided in a direction of transfer is arranged over a wafer 1 placed on a suspected, high-pressure gas b is spouted out in the direction of transfer through a gas outlet 61a provided to the underside of the transfer plate 61, whereby the wafer 1 is transferred being levitated in the air. In this case, provided that the flow speed S of high-pressure gas b is equal to 122 to 215[m/s], the mass and surface area of the wafer 1 are expressed by M[g] and A[cm2 ] respectively, and a distance between the transfer plate 61 and the suspected is expressed by L, L is so set as to satisfy a formula, (M/A)×L<2> =0.018 to 0.042, wherein the flow rate F of the high-pressure gas b spouted out through the gas outlet 61a is so set as to satisfy a formula, F=0.08 to 0.17[M<3> /min].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer transfer method, and more particularly to a method for transferring a wafer in a non-contact manner by an air flow in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art With the increasing integration of semiconductor devices, it is necessary to prevent the wafer from being damaged or contaminated even when the wafer is transferred during the manufacturing process of the semiconductor device in order to suppress a decrease in yield. Is becoming extremely important. As a method of transferring the wafer, there are a method of transferring the wafer while it is held by a mechanical chuck and a method of transferring the wafer by a belt. However, in the method of holding and transferring the wafer by the mechanical chuck, it is necessary to form a groove into which the mechanical chuck is placed on the surface of the susceptor on which the wafer is placed. For this reason, the surface temperature of the wafer placed on the susceptor becomes non-uniform, and if this method is applied to an epitaxial device, crystal defects may occur in the formed epitaxial layer. Further, the method of carrying the belt cannot structurally be applied to the vertical epitaxial device. For this reason, in the vertical epitaxial device, a person manually puts the wafer in and out of the device. However, with the increase in the diameter of the wafer, considerable skill is required to manually load and unload the wafer into and from the apparatus.

Therefore, an air flow carrier as disclosed in JP-A-61-37622 and JP-A-2-89721 has been proposed. As shown in FIG. 6, the air flow carrier 6
Is the gas supply path 6 via the carrier plate 61 arranged on the upper part of the wafer 1 placed on the susceptor 2, the gas supply path 62 provided on the upper part of the carrier plate 61, and the gas control unit 63.
2 is provided with a gas supply source 64 connected to No. 2 and a wafer receiver 65 arranged in the transfer direction of the wafer 1 while being connected to the gas control unit 63. The transfer plate 61 and the wafer receiver 65 form a transfer unit 66. Then, for example, as shown in FIG. 7, the gas supply paths 62 provided in the upper portion of the transfer plate 61 are arranged in two rows along the wafer transfer direction, and the gas supply paths 62 are provided on the lower surface side of the transfer plate 61. A plurality of blow-out holes 61a for blowing out the high-pressure gas therein in the wafer transfer direction are provided.

When a wafer is transferred using the air flow transfer device, a transfer plate 61 is arranged above the wafer 1 placed on the susceptor 2 as shown in FIG.
High-pressure gas is blown out from the No. 1 blow-out hole (61a). As a result, the wafer 1 is levitated from the susceptor 2, and the levitated wafer 1 is transported by air in the transport direction. In the method of transferring the wafer 1 using the airflow transfer device 6, the wafer 1 can be transferred in a non-contact manner and it is not necessary to add a special configuration to the susceptor 2, so that the surface temperature of the wafer 1 on the susceptor 2 varies. Therefore, it can be applied to an epitaxial device and a vertical epitaxial device. FIG. 8 shows, as an example, a configuration diagram of a vertical epitaxial device 8 in which the air flow carrier 6 is provided in the wafer carry-out means.

[0005]

However, as shown in FIG. 9, it is confirmed that the dust 91 is attached to the surface of the wafer 1 transferred by using the airflow transfer device at a position corresponding to the position of the blowout hole. To be done. This is because dust accumulated in the gas supply passage is blown out together with the high pressure gas, or quartz constituting the blowout hole of the high pressure gas is chipped by the blowout of the high pressure gas. In wafer transfer using the above-described airflow transfer device, the wafer transfer state is stabilized by increasing the blowing speed of the high-pressure gas. Therefore, when trying to stabilize the transport state, chipping of the blowout hole due to high pressure gas becomes severe,
The amount of dust 91 adhering to the surface of the wafer 1 will increase. Since the dust 91 becomes a factor that reduces the yield of the semiconductor device, the airflow carrying device has not been practically used.

[0006]

In view of the above, according to the wafer transfer method of the present invention, in the method of transferring a wafer in a floating state by using an airflow transfer device, the transfer is arranged above the wafer placed on the susceptor. The flow velocity of the high-pressure gas blown out from the blowout holes of the plate is S = 150 to 215 [m / s], the mass of the wafer is M [g], and the one surface area of the wafer is A.
[Cm ² ], the distance between the carrier plate and the susceptor is L
When it is [cm], (M / A) × L ² = 0.018 to
The distance L between the carrier plate and the susceptor is set in the range of 0.042, and the flow rate of the high-pressure gas blown out from the blowing hole becomes F = 0.08 to 0.17 [m ³ / min]. I am trying.

In the above wafer transfer method, the flow velocity of the high-pressure gas blown out from the blow-out hole is S = 122 to 215 [m /
[s] is set to a low value to prevent the high-pressure gas blown from the blowing hole from chipping the blowing hole. Also, (M / A) × L ² = 0.01
8 to 0.042, F = 0.08 to 0.17 [m ³ / mi
Since the distance L between the susceptor and the transfer plate is set within the range of n], the wafer can be transferred stably even at the above flow rate.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A wafer transfer method of the present invention will be described below based on an embodiment applied to a method for carrying a wafer 1 out of a susceptor 2 of a vertical epitaxial device 8 shown in FIG. The wafer transfer method described here is
This is a wafer transfer method using the airflow transfer device 6 having the structure described in the related art, and the description of the structure of the airflow transfer device 6 is omitted. The wafer 1 carried out from the vertical epitaxial device 8 by using the air flow carrier 6 is soft landed by inclining the wafer 1 obliquely by using the carrier disclosed in, for example, Japanese Patent Laid-Open No. 63-164234. It is assumed to be placed on the susceptor 2 as described above.

FIG. 1 is a cross-sectional view of the main part of the susceptor 2 on which the wafer 1 is placed. As shown in this figure, the susceptor 2 is formed by, for example, forming a mounting portion of the wafer 1 in a concave shape having a depth of about 500 μm. When carrying out (transporting) the wafer 1 placed on the susceptor 2, first, the wafer 1 is placed above the wafer 1 so as to satisfy the following first condition and second condition. The distance L between the transport plate 61 and the susceptor 2, the flow velocity S of the high-pressure gas b blown out from the blowout hole 61a provided in the transport plate 61, and the flow rate F of the high-pressure gas b are defined. The interval L between the transfer plate 61 and the susceptor 2 is the interval between the transfer plate 61 and the susceptor 2 in the transfer part of the wafer 1. Also, the susceptor 2
May be a wafer 1 on which the mounting portion and the transfer portion are formed flush with each other.

First, the first condition is that the flow velocity of the high-pressure gas b blown out from the blow-out hole 61a is S = 122 to 215.
It is defined in the range of [m / s]. In FIG. 2, the flow rate S of the high-pressure gas and the number of dust particles (0.
And a particle size of 3 μm or more). As shown in this figure, the dust on the wafer surface increases as the flow velocity S of the high-pressure gas increases. When the flow velocity S = 215 [m / s] or less, the amount of dust generated is in a range in which there is no problem. Therefore, the flow velocity S = 215 [m / s] or less. Further, as shown in FIG. 3, the flow velocity S = 122
Since the wafer is conveyed in a stable state at [m / s] or more (provided that the diameter of the wafer is 150 mm and the interval L = 4 mm), the flow rate is S = 122 [m / s] or more.

The second condition is that the wafer 1 to be transferred is
Is the mass of M [g], the area of one side of the wafer 1 (one surface area)
Is A [cm ² ], (M / A) × L ² = 0.
018 to 0.042 and flow rate F = 0.08 to 0.17
The interval L and the flow rate F of the high-pressure gas are defined so as to be [m ³ / min]. As shown in FIG.
In the above range, good linearity is obtained between (M / A) × L ² and the flow rate F. From the above, when the mass of the wafer to be transferred is M [g] and the one surface area of the wafer is A [cm ² ] in the range of the flow velocity S = 122 to 215 [m / s] specified in the above first condition. And (M / A) × L ² =
0.018-0.042, flow rate F = 0.08-
The above-mentioned interval L, 0.17 [m ³ / min]
The flow rate F and the flow rate S are specified.

As a concrete example, when a wafer 1 having a diameter of 15 cm is transferred, one surface area of the wafer 1 is A =
176.6 [cm ² ], and the mass of the wafer 1 is M = 2
It becomes about 5.72 [g]. Therefore, L ² = (0.
018-0.042) / (M / A) = 0.123-0.
288, and the distance L becomes 0.35 to 0.54 [cm]. Here, the height of the wafer 1 is T = 0.0625.
When the distance is about [cm], the above-mentioned interval L is the height T of the wafer 1.
Range larger than the value of, that is, the interval L = 0.35-
It goes without saying that it is selected within the range of 0.54 [cm]. Then, from FIG. 4, the flow rate F = 0.08 to 0.17.
It is specified in the range of [m ³ / min]. Further, the flow velocity S for realizing the value of the flow rate F is the flow velocity S = 122 to 21.
It is specified in the range of 5 [m / s].

After defining the respective values as described above, for example, as shown in FIG. 1, the arm (not shown) to which the carrier plate 61 is attached is driven, and the susceptor 2 is moved to the DC servo motor (not shown). The carrier plate 61 is moved onto the wafer 1 by being rotationally driven by. At this time, the wafer 1
Orientation Flat (hereinafter referred to as "Orifla")
It is assumed that the wafer 1 is arranged on the susceptor 2 so that the wafer 1a is the rearmost portion in the carrying direction a.

Further, in order to stabilize the transfer of the wafer 1, among the plurality of blow-out holes 61a formed in the lower surface of the transfer plate 61, the blow-out hole 61a located rearward of the wafer 1 in the transfer direction a. Position and orientation flat 1 of wafer 1
so that the distance W from the position a is about 2 to 3 mm,
A carrier plate 61 is arranged on the wafer 1. At this time, the wafer 1
The positioning of the carrier plate 61 with respect to the sheet is described in JP-A-3-1291
9 is disclosed, a slit (not shown) provided in the susceptor 2 is detected by a transmissive sensor (not shown). The interval W is the interval between the blowout hole 61a and the orientation flat 1a when the surface of the wafer 1 is viewed from above.

After that, the carrier plate 61 arranged immediately above the wafer 1 is lowered so that the distance L between the susceptor 2 and the carrier plate 61 becomes the above-mentioned specified value. At this time, the conveyance plate 61 is detected while detecting the interval L using a displacement sensor (not shown).
Descend. Next, the gas pressure in the gas supply passage (62) is set by the gas control unit (63) described with reference to FIG. 6 so that the flow velocity S becomes the specified value within the range, and the blowout hole 61a is set. A high-pressure gas b made of an inert gas such as high-purity nitrogen (N ₂ ) or argon (Ar) is blown from the above.

According to the above procedure, the wafer 1 is levitated by the Bernoulli's principle without chipping the end portion of the blowing hole 61a with the high pressure gas b, and the high pressure gas b is blown out (that is, the transfer direction). Can be conveyed in a stable state. On the other hand, when the values of the interval L, the flow rate F, and the flow velocity S deviate from the respective prescribed values, dust chipped with blowing holes adheres to the surface of the wafer 1 transferred using the airflow transfer device. , It may not be possible to carry out stable transportation.

While the wafer 1 is being carried in a stable state as described above, the high-pressure gas b is blown from the blowing hole 61a while the wafer is not being carried by the airflow carrier. Purging the gas in the gas system piping. In this case, as shown in FIG. 5, the gas is intermittently blown to perform intermittent purging. This is performed at least within a predetermined time before disposing the transfer plate on the wafer while the transfer of the wafer is stopped. The predetermined time period is a time period in which high pressure gas does not accumulate in the gas pipe system of the air flow carrier by stopping the air flow carrier, and dust is not accumulated in the gas pipe system. By doing so, it is possible to prevent dust from being blown out together with the high-pressure gas from the blowing hole during wafer transfer.

[0018]

As described above, according to the wafer transfer method of the present invention, in a method of transferring a wafer in a floating state using an airflow transfer device, the high pressure gas for floating the wafer blows off the high pressure gas. By setting the distance L between the carrier plate and the susceptor within a range in which the flow rate at which the wafer is stably carried at a flow velocity that does not cause chipping of the holes is maintained, the wafer can be stably held without adhering dust to the wafer surface. It becomes possible to carry air. Therefore, in the manufacturing process of the semiconductor device, wafer transfer using the airflow transfer device can be realized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a wafer transfer method.

FIG. 2 is a graph showing a blowing flow velocity and the number of dusts.

FIG. 3 is a chart showing blowing velocity and conveyance stability.

FIG. 4 is a graph showing a relationship between a flow rate of blown air and a distance between a carrier plate and a susceptor.

FIG. 5 is a timing chart showing an example of intermittent purging.

FIG. 6 is a configuration diagram of an air flow carrier.

FIG. 7 is a plan view and a cross-sectional view of a carrier plate.

FIG. 8 is a configuration diagram of a vertical epitaxial device provided with an air flow carrier.

FIG. 9 is a diagram showing the adhesion of dust on the wafer surface by air flow conveyance.

[Explanation of symbols]

1 Wafer 1a Orientation flat
2 susceptor 61 carrier plate 61a blowout hole 62 gas supply path a carrier direction b high pressure gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Nakagama 5-1 Noguchikita, Kokubun-shi, Kagoshima Sony Kokubun Co., Ltd. (72) Yoshifumi Hamada 5-1 Noguchikita, Kokubun-shi, Kagoshima Sony Kokubun shares In the company

Claims (4)

[Claims] 1. A gas supply path is provided along the transport direction.
The transfer plate above the wafer placed on the susceptor
From the blowout hole provided on the lower surface side of the carrier plate.
High pressure in the gas supply path toward the wafer transfer direction
The state that the wafer is levitated by blowing out gas.
In the wafer transfer method of transferring in a state, the flow rate of the high-pressure gas blown out from the blowout hole is S =
122 [m / s] to 215 [m / s]
Mass is M [g], and one surface area of the wafer is A [cm] ^Two〕,Before
When the distance between the carrier plate and the susceptor is L [cm].
In total (M / A) × L^Two= 0.018 to 0.042
And the flow of the high-pressure gas from the blow-out hole
The amount is F = 0.08 [m^Three/ Min] to 0.17 [m^Three/
min], the transfer plate and the susceptor
A wafer transfer method characterized in that an interval L is set. 2. The wafer transfer method according to claim 1, wherein the orientation flat of the wafer is located at a rear portion in the transfer direction of the wafer, and the position of the blowing hole is located behind the orientation flat in the transfer direction. A wafer transfer method, wherein the transfer plate is arranged on the upper part of the wafer so that a distance W between the position and the orientation flat is about 2 to 3 mm. 3. The wafer transfer method according to claim 1, wherein the high pressure gas is intermittently blown out from the blowing hole at least within a predetermined time before the transfer plate is placed on the upper part of the wafer. Wafer transfer method. 4. The wafer transfer method according to claim 2, wherein high-pressure gas is intermittently blown out from the blowing hole at least within a predetermined time before the transfer plate is placed on the upper part of the wafer. Wafer transfer method.