JPH0736377B2 - Double-sided wafer exposure system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exposure apparatus used for forming patterns on both front and back surfaces of a wafer when forming various thin films in thin film integrated circuits such as LSI and MOS integrated circuits. Is related to the structure of.

[Conventional technology]

Since various conductor layers such as collectors, bases, and emitters and semiconductor layers are formed in a predetermined pattern on both front and back surfaces of a wafer that is a semiconductor substrate of this kind of LSI, etc. After applying resist on both front and back surfaces of the wafer in advance, one side is covered with a pattern mask for exposure, and then the wafer is turned over and the back side of the pattern is phase-matched with another pattern for exposure, and then the development step is performed. After that, it is divided into a predetermined number of chips.

And, as this exposure apparatus, as shown in FIG.
As shown in the figure, a wafer chuck for vacuum-adsorbing the light emitting lamp 20, the lens system 21, the pattern mask 22, and the wafer 23.
24, the surface of the wafer chuck 24 is formed with a large number of concentric annular grooves 25. The annular grooves 25 are communicated with each other and connected to a vacuum pump (not shown) via a tube 26 on the back surface of the wafer chuck 24. It has a structure.

[Problems to be solved by the invention]

In order to form a pattern on both sides of a wafer by using the exposure apparatus having such a configuration, first, the wafer 23 is placed on the wafer chuck 24 and vacuum-adsorbed, and this is placed on the lower surface side of the pattern mask 22. First, the light-emitting lamp 20 is turned on, and after a pattern of a predetermined shape is exposed on the upper surface of the wafer 23, the wafer chuck 24 is moved away from the pattern mask 22, and the wafer 23 on the wafer chuck 24 is turned upside down to be vacuum-adsorbed. Then, the step of exposing again through another pattern mask 22 is taken.

However, at the time of turning over the wafer 23, unless another pattern is formed on the back surface side of the pattern formed by the first exposure with the same position and the same phase, both front and back surfaces of each chip are divided at the time of dividing the chip in a later process. Therefore, the desired pattern is not formed on the wafer, and the entire wafer becomes defective.

However, if the wafer is turned upside down manually, the position and phase of vacuum suction on one side of the wafer and the position and phase of vacuum suction on the other side of the wafer for the second time easily shift, and the defect occurrence rate of the wafer cannot be reduced. In addition, there is a problem in that the work itself to be accurately installed requires a great deal of time and work efficiency cannot be improved.

It is an object of the present invention to solve the above-mentioned problems by using a pair of wafer chucks and to make it possible to automate the exposure operation.

[Means for solving problems]

Therefore, the present invention is an exposure apparatus configured to expose one surface of a wafer by vacuum chucking the wafer on the other surface of the wafer through a predetermined pattern mask. A pair of wafer chucks are provided, and a wafer exposed on one of the wafer chucks is sandwiched between the wafers exposed on the wafer chuck such that the wafer chuck and the other wafer chuck face each other. The vacuum suction is switched to transfer the wafer to the other wafer chuck, and the unexposed one side is exposed.

[Operation and effect of the invention]

In this way, of the pair of wafer chucks that vacuum-suck one side of the wafer, after exposing the wafer that is vacuum-sucked to one wafer chuck, the wafer chuck that vacuum-sucks the wafer and the other wafer chuck, When vacuum suction is switched in a state where the vacuum suction surfaces of both wafer chucks face each other with the wafer sandwiched therebetween, the wafer chuck is transferred to the other wafer chuck in a state where the already exposed surface is vacuum suctioned. be able to.

Therefore, a thin wafer can be flipped from one wafer chuck to the other wafer chuck without manual work,
That is, the unexposed surface can be easily delivered with the surface facing outward.

At this time, since the vacuum suction is applied to both wafer chucks while sandwiching the wafer by the pair of wafer chucks, and then the vacuum suction of one is cut off, the vacuum suction is switched from one to the other. When the wafer is transferred, the position of the wafer in the X and Y directions parallel to the surface of the wafer chuck and the rotation phase of the wafer itself cannot be generated.

Then, the wafer for which the transfer operation has been completed is transferred to the wafer chuck because the exposed surface is vacuum-sucked to the wafer chuck and the unexposed surface is exposed to the outside as described above. By arranging the other wafer chuck again on the transmitted light side of the pattern mask, the next exposure operation can be performed as it is. In this case, considering a state in which a pair of wafer chucks are arranged on the left and right sides, the orientation of the wafer placed on one of the wafer chucks is opposite on the transferred wafer chuck, that is, a so-called symmetrical shape. The arrangement of the pattern mask in the subsequent exposure may be determined in consideration of the above.

As described above, according to the present invention, the wafer transfer operation for exposing both front and back surfaces is extremely simple, and there is no shift in the position and phase of the wafer during the wafer transfer operation from one wafer chuck to the other wafer chuck. Since it is completely eliminated and can be performed accurately, there is an effect that the positioning work and the phase setting work can be configured as an automated device without human intervention, and it is possible to reduce the defect rate at the time of pattern formation and improve the work efficiency. Play.

〔Example〕

An embodiment of the present invention will now be described. The exposure apparatus 1 shown in FIG. 1 has a single illumination system including a light emitting lamp 2 and a lens 3. Below the lens 3, a pair of wafers are appropriately separated on the left and right sides. 4a and 4b are arranged so that the vacuum suction surface faces upward.

Below the lens 3, a rotating mirror 6 which can rotate 90 ° about a horizontal axis is arranged, and on the left and right sides of the mirror 6, fixed mirrors 7 and 8 are similarly arranged. Each wafer chuck 4
Pattern disks 5a and 5b are arranged above a and 4b at appropriate intervals.

Each of the wafer chucks 4a and 4b has the same structure as the vacuum suction type in the prior art, that is, as shown in FIG.
A large number of concentric annular grooves are formed on the upper surface of the wafer chuck, and the annular grooves are connected to each other and connected to a vacuum pump (not shown) through a communication pipe on the back surface of the wafer chuck. The communication pipe between each wafer chuck has an operation valve capable of appropriately shutting off the vacuum to the wafer chuck.

Further, the both wafer chucks 4a, 4b are configured to be movable so that the two wafer chucks 4a, 4b can approach or move away from each other in a horizontal state, and both wafer chucks 4a, 4b can approach each other to a certain extent. It is configured to be rotatable so that the suction surfaces face each other.

With this configuration, the wafer chuck on the right side in FIG.
When an unexposed wafer 10 is placed on the upper surface of 4a and the wafer chuck 4a is brought into communication with a vacuum pump, the lower surface of the wafer 10 is so-called vacuum-sucked, and the wafer 10 is not displaced and is substantially flat without distortion. Can be placed in a state.

The wafer chuck 4a is arranged on the lower surface side of the predetermined pattern mask 5a, and the rotary mirror 6 is fixed to the fixed mirror 7 whose reflection surface is one.
After turning so as to face the reflective surface of the
When the light is emitted from the above, the pattern of the pattern mask 5a is printed on the upper surface of the wafer 10.

Next, the wafer chucks 4a and 4b are moved in parallel with each other while the vacuum chucking action is being applied to the wafer chucks 4a (direction of arrow A). Then, the wafer chucks 4a and 4b are rotated upward in the direction of arrow B so that the two wafer chucks 4a and 4b are brought close to each other with their vacuum suction surfaces facing each other.

After the wafer 10 is held between the two wafer chucks 4a and 4b, the vacuum suction action on the other wafer chuck 4b is started, and the wafer 10 is held against the wafer chuck 4b.
If the vacuum suction of the one wafer chuck 4a is interrupted while the exposed surface of the wafer is vacuum-sucked, the wafer 10 can be transferred to the other wafer chuck 4b in the vacuum suction state.

Next, the both wafer chucks 4a, 4b are rotated in the direction of arrow C in FIG. 2 and returned so that the vacuum suction surfaces of the both wafer chucks 4a, 4b face upward.

Then, while the other wafer chuck 4b is horizontally moved (in the direction of arrow D) toward the lower surface side of the pattern mask 5b, the rotating mirror 6 is rotated to face the other fixed mirror 8, and in this state. By irradiating light from the light emitting lamp 1 on both sides, the front and back surfaces of the wafer 10 can be printed in a predetermined pattern.

Then, the vacuum suction action of the other wafer chuck 4b is released and the wafer 10 is removed. In addition, it is preferable from the standpoint of work efficiency that another wafer 10 is placed on one wafer chuck 4a during the printing operation on the other wafer chuck 4b to complete the preparation.

In the above-described embodiments, the illumination system is the one-illumination system in which the light emitting lamp 1 and the lens system 2 are provided one by one, and the turning mirror 6 selects the light irradiation position to either left or right. It goes without saying that a two-illumination system type configuration including the light emitting lamp 1 and the lens system 2 can be applied to each of the pattern masks 5a and 5b.

Further, in the above embodiment, the pair of wafer chucks 4a, 4b
The two wafers were horizontally moved, faced each other, and rotated to move them away from each other, but instead, one of the wafer chucks, for example, the wafer chuck 4a, faces the pattern mask 5a and faces the pattern mask 5a, and moves away from it. The wafer chuck 4b on the other side only
It may be configured to perform a 180-degree rotation operation capable of facing the wafer chuck 4a in the distant position so as to cover it and a movement operation in the direction of the other pattern mask 5b.

In the present invention, since the wafer chucks 4a and 4b hold the wafer 10 in a fixed state by vacuum suction and cannot be removed, the irradiation light during the baking operation is substantially horizontal, and the surface of the wafer 10 is vertical. It may be arranged to face.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory view of its operation, FIGS. 3 and 4 show prior art, and FIG. 3 is a side view of the apparatus, FIG. FIG. 4 is a plan view taken along the line IV-IV in FIG. 1 ... exposure device, 2,20 ... light emitting lamp, 3,21 ... lens system, 4a, 4b, 24 ... wafer chunk, 5a, 5b, 22 ... pattern mask, 6 ... rotating mirror, 7 , 8 …… Fixed mirror, 10,23 …… Wafer, 25 …… annular groove, 26 …… Tube.

Claims (1)

[Claims] 1. An exposure apparatus configured to expose one surface of a wafer to the other surface of the wafer through a predetermined pattern mask while the one surface of the wafer is vacuum-adsorbed by the wafer chuck. A pair of wafers, one of which is exposed to the wafer, and the other wafer chuck is sandwiched by facing the wafer chuck and the other wafer chuck, and the other wafer chuck is switched by switching vacuum suction of both wafer chucks. A wafer double-sided exposure apparatus, characterized in that the wafer is transferred to and exposed on one side of the wafer not exposed.