JPH0878316A - Exposure system - Google Patents

Abstract

PURPOSE: To make accurate coarse positioning possible at the time of a pattern exposure at a first level in a wafer not patterned, to which no patterning is conducted. CONSTITUTION: An exposure system is composed of a stage 1, a coarse positioning mechanism 2, and a number detecting means 3, the stage 1 is moved in the longitudinal and lateral directions and the direction θ of rotation, at least three abuttedly fixing members 1a coarsely positioning a wafer 4 are mounted, and the coarse positioning mechanism 2 abuts the peripheral section of the wafer 4 placed on the stage 1 against the abuttedly fixing members 1a by pushing operation and coarsely positions the wafer 4. The number detecting means 3 detects an identification number 4a marked on the coarsely positioned wafer 4, and the stage 1 is moved until the identification number 4a is placed at a specified position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus, such as a reduction projection exposure apparatus, which can determine the rough positioning state of an unexposed wafer (hereinafter referred to as an unpatterned wafer) which has not been patterned. .

As the degree of integration of semiconductor devices increases, the performance of exposure apparatuses used in lithography, which is a key process in the manufacturing process, is increasing. Generally, lithography is evaluated from the viewpoint of accuracy and economical efficiency, but the accuracy is evaluated with two kinds of accuracy including pattern accuracy and overlay accuracy. Therefore, it is a technical concern how to obtain high accuracy in the exposure apparatus.

By the way, the overlay accuracy is the accuracy of the relative size, shape, position, etc. between levels in a composite pattern in which patterns of a plurality of levels are transferred. A number of methods have been developed to achieve a predetermined accuracy, and high-precision overlay is becoming possible.

Generally, for superposition, a means for photoelectrically reading the positional deviation of the superposition mark is used. However, since the range for reading the overlay mark is a very narrow range of several tens of μm, rough positioning of the wafer is required once before reading the mark.

However, if there is a problem in the rough positioning of the wafer, overlay measurement cannot be performed because there is no overlay mark at the expected position. As a result, the device stops due to an error, and the overlay mark must be moved to a position where overlay measurement can be performed each time. Thus, the throughput is significantly reduced. In particular, there is a need for a means for determining whether or not the first-level coarse positioning for exposing the most basic unpatterned wafer is completed.

[0006]

2. Description of the Related Art FIG. 3 is a schematic view of a conventional coarse positioning method. In the figure, 1 is a stage, 1a is a stop member, 4 is a wafer, and 4b is an orientation flat (orientation flat).
Is.

A rough positioning method for overlaying in a conventional exposure apparatus is as follows. That is, for example, three stop members 1a are provided on the stage 1 included in an exposure device (not shown). Then, the wafer 4 is mechanically pressed on the stage 1 by a coarse positioning mechanism (not shown) as shown by an arrow to move the orientation flat 4b to 2
The book stopper member 1a is hit and the remaining one hit member 1a is hit to the peripheral edge of the wafer 4 for positioning. In such rough positioning for mechanically pressing the wafer 4, whether or not the wafer 4 is positioned within a predetermined range depends on the reliability of the apparatus at present.

[0008]

By the way, when a problem occurs in the pressing mechanism, the deviation of the overlay mark from the expected position becomes large after the exposure of the second level. Relatively easy. However, in the case of performing the first level exposure on a wafer without a pattern, it is left to the apparatus, and it is difficult to find it even if a positional misalignment problem occurs.

Therefore, even if a defect is found after the exposure of the second level, many defective work-in-progress remains during that period. Therefore, it is an object of the present invention to provide an exposure apparatus provided with a means for confirming that there is no defect in positioning during the first level exposure of an unpatterned wafer.

[0010]

SUMMARY OF THE INVENTION The above-mentioned problem is, in an exposure apparatus having a stage, a coarse positioning mechanism, and a number detecting means, the stage is movable in the front and rear / left and right XY directions and the rotational θ direction. At least three stopper members for roughly positioning the wafer are provided, and the rough positioning mechanism abuts the peripheral edge portion of the wafer placed on the stage against the stopper member by a pressing operation. Coarse numbering, and the number detecting means detects the identification number imprinted on the roughly positioned wafer, and moves the stage until the identification number is in a predetermined position. This is solved by the exposure apparatus configured in.

[0011]

In the past, since the unpatterned wafer has no positioning mark, the rough positioning mechanism presses the wafer to perform rough positioning, and mechanical movement causes problems frequently.However, in the present invention, the position of the wafer is detected. Therefore, the problem of rough positioning is solved.

That is, the identification number engraved on the unpatterned wafer is photoelectrically detected by the number detecting means. If the predetermined positioning is not achieved only by the movement of the coarse positioning mechanism, the stage is moved in the front and rear / left and right XY directions and the rotational θ direction to position the wafer at the predetermined position. There is.

With this arrangement, the first level exposure, which is the most base of the unpatterned wafer, can be accurately performed at a predetermined position.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of an embodiment of the present invention. FIG. 1A is a configuration diagram of a main part of the apparatus, FIG. 1B is a process diagram of rough positioning, and FIG. In the enlarged view of the field of view, the figure (A) shows the rough positioning completed state, and the figure (B) shows the rough positioning incomplete state. In the figure, 1 is a stage, 1a is a stop member, 2 is a rough positioning mechanism, 3 is a number detecting means, 3a is a mask, 4 is a wafer, 4a is an identification number, 4b is an orientation flat,
Reference numeral 10 is an exposure device.

In FIG. 1, an exposure apparatus 10 according to the present invention comprises a number detecting means 3 in addition to a stage 1 and a coarse positioning mechanism 2. The stage 1 is capable of linear movement in the front and rear / left and right XY directions and rotational movement of θ.
Then, the three stopper members 1a are projected and the wafer 4
It is possible to perform rough positioning by hitting.
The rough positioning mechanism 2 pushes the wafer 4 and abuts the peripheral edge of the wafer 4 against the stop member 1a to perform rough positioning. The number detecting means 3 is composed of an image pickup device such as a CCD camera and is arranged above the stage 1. Then, the identification number 4a is stamped near the orientation flat 4b of the wafer 4 roughly positioned on the stage 1 by, for example, laser engraving.
Is detected through the mask 3a.

In FIG. 1B, the wafer 4 pressed by the rough positioning mechanism 2 for rough positioning is placed in the mask 3a when observed by the number detecting means 3 as shown in FIG. 2A. If the identification number 4a is within, for example, X
The stage 1 is moved in the direction, the identification number 4a is read, and the process moves to the next exposure step. However, as shown in FIG. 2B, the identification number in the mask 3a when observed by the number detecting means 3.
If 4a does not fit, move it in the Y direction,
Search for the identification number 4a by rotating it in the θ direction and then
For example, the stage 1 is moved in the X direction to read the identification number 4a, and the next exposure process is performed.

The reading of the identification number 4a can be regarded as rough positioning if the position of the number is within the mask 3a even if the number itself is not necessarily read by character recognition or the like.

Here, the case where a circular semiconductor wafer is picked up and the identification number 4a is near the orientation flat 4b has been described, but the present invention is not limited to this. Further, the present invention can be applied to rough positioning of a wafer other than a semiconductor or a rectangular substrate such as glass, and various modifications are possible.

[0019]

According to the present invention, reliable rough positioning can be performed at the first level exposure of a pattern-free wafer having no positioning mark for the first exposure. As a result, it is possible to prevent the poor positioning of unpatterned wafers from causing misalignment after the second level exposure, which contributes greatly to the improvement of wafer process efficiency and throughput. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, in which FIG. 1A is a configuration diagram of a main part of an apparatus, and FIG. 1B is a process diagram of rough positioning.

FIG. 2 is an enlarged view of the visual field of the number detecting means, which is shown in FIG.
Is a rough positioning completed state, and FIG. 7B is a rough positioning incomplete state.

FIG. 3 is a schematic diagram of a conventional coarse positioning method.

[Explanation of symbols]

1 Stage 1a Stop member 2 Coarse positioning mechanism 3 Number detection means 3a Mask 4 Wafer 4a Identification number 4b
Orifla 10 exposure equipment

Claims (2)

[Claims] 1. A stage, a coarse positioning mechanism, and a number detecting means are provided, and the stage moves in the front and rear / left and right XY directions and in the rotational θ direction, and at least 3 for roughly positioning the wafer. Individual anti-stop members are provided, and the rough positioning mechanism is for performing rough positioning by abutting the peripheral edge of the wafer placed on the stage against the anti-stop member by a pressing operation. An exposure apparatus, wherein the means detects an identification number imprinted on the roughly positioned wafer, and moves the stage until the identification number is located at a predetermined position. 2. The exposure apparatus according to claim 1, wherein the wafer is an unpatterned wafer that has not been patterned yet.