JP4401834B2 - Exposure apparatus and alignment method - Google Patents

Description

  The present invention relates to an exposure apparatus and an alignment method.

  In recent years, printed wiring boards have been miniaturized and miniaturized, and are manufactured using a photolithographic method in which a circuit or the like is formed on a substrate using an exposure apparatus, as in the case of semiconductor manufacturing. That is, a printed circuit board is manufactured by forming a predetermined pattern on the substrate surface by an exposure apparatus and then forming the pattern on the substrate by an etching process on a substrate surface coated with a photosensitive material such as a photoresist.

In this exposure apparatus, a photomask such as a resin film or glass is used as an original on which an original pattern is drawn. In exposure, alignment of the photomask and the substrate is important for obtaining a highly accurate product.
For this reason, it is usual to form a mark for alignment on the photomask and the substrate side and perform alignment based on the mark. Usually, alignment is performed by providing a plurality of marks on the photomask and the substrate side, obtaining the center of gravity of the mark, and matching the center of gravity.

However, printed circuit boards and photomasks may expand and contract due to temperature, humidity and other process reasons, and the alignment between the photomask and the substrate using the center of gravity described above is insufficient. It has become to. In particular, the problem of accuracy has been increasing in the production of printed wiring boards having a high-density pattern in recent years.
The object of the present invention is to solve the problems of the prior art.

In order to achieve the above object, an exposure apparatus of the present invention is provided at a plurality of positions P on a substrate to be exposed, and aligns the substrate with a photomask on which a pattern to be exposed is drawn. A plurality of substrate marks, a plurality of mask marks provided on the photomask corresponding to each of the plurality of substrate marks, and the substrate and the photomask are aligned, and each of the P points at each time point Means for detecting a position deviation Dp of the mask mark corresponding to the substrate mark, means for detecting the maximum value MDp of the deviation Dp, means for detecting the maximum value MDp each time by repeating the alignment N times, Means for detecting a minimum value MDmin among the N maximum values MDp; means for determining whether or not the minimum value MDmin is equal to or less than a predetermined value; And When it is determined, characterized by comprising means for determining the most appropriate alignment position alignment position of the MDmin was obtained the n-th and.

  According to the exposure apparatus of the present invention, there is an effect that optimum alignment between the substrate and the photomask can be performed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an exposure apparatus for manufacturing a printed wiring board. A substrate W coated with a photoresist is placed on a platen 3 and can be moved in XYZ and θ directions by a moving mechanism 2.

  The photomask M on which the circuit pattern is drawn is provided so as to face the substrate W. The photomask M and the substrate W are brought close to or in close contact with each other, and the circuit pattern is printed on the substrate W by exposure from the exposure light source 5. ing.

In FIG. 1, the substrate W and the photomask M are arranged in the vertical direction. However, the substrate W and the photomask M are not limited to this and may be reversed, or the substrate W and the photomask M are set up vertically. It is also possible to have a structure in which the two are arranged.
Further, it is possible to move the photomask M instead of moving the platen 3, and it is also possible to further move both.

Substrate mark 10 and mask mark 20 are provided at positions corresponding to substrate W and photomask M, respectively. In this embodiment, marks are provided at positions P1, P2, P3, and P4. The CCD cameras 4 and 4 detect the deviation Dp between the substrate mark 10 and the mask mark 20 at each point Pn, thereby realizing the optimum alignment between the substrate W and the photomask M.
Image signals from the CCD cameras 4 and 4 are sent to the arithmetic and control unit 1, and the arithmetic and control unit 1 controls the moving mechanism 2 to move the platen 3 for alignment.

  The arithmetic control device 1 is provided with a detection device 7 and a discrimination / determination device 8. The detection device 7 detects a deviation of a mark and the like, and the discrimination / determination device 8 performs discrimination and determination. Yes. The operations of the detection device 7 and the discrimination / determination device 8 will be described later. The arithmetic control device 1, the detection device 7, and the discrimination / determination device 8 are configured by a computer or the like.

In FIG. 2, it is assumed that the substrate W is displaced by Δ due to deformation, as shown in FIG.
In such a situation, even if the center of gravity of the mask and the center of gravity of the substrate coincide with each other as in the prior art, only 3 / 4Δ is corrected at the point P2 as shown in FIG.
Therefore, if the standard value is less than 3 / 4Δ, the printed board W becomes a defective board although it has been aligned and exposed.

In the present invention, as shown in FIG. 2B, alignment is performed N times without performing alignment based on the center of gravity, and a mark shift Dp is detected at each of the points P1 to P4. It is configured to determine a position.
In addition, it is desirable to perform the alignment of N times by simulation by calculation.

The configuration will be described below with reference to FIG.
<Step 1>
First, primary alignment is performed, and setting is performed so that the substrate mark 10 and the mask mark 20 are within the field of view of the CCD camera 4 (S1).

<Step 2>
The substrate W and the mask M are aligned, and a deviation Dp between the substrate mark 10 and the mask mark 20 at P1, P2, P3, and P4 is detected (S2). Among these, the maximum value MDp is stored (S3).

<Step 3>
Step 2 is repeated N times (S4), N maximum values MDp are detected, and a minimum value MDpmin among them is obtained (S5).
These detections are performed in the detection device 7.

<Step 4>
The determination / determination device 8 determines whether or not MDpmin <predetermined value (S6). If it is equal to or less than the predetermined value, the n-th alignment position where the minimum value MDpmin is detected is determined as the optimum position (S7).
If not less than the predetermined value, the substrate W is determined to be defective (S8).

With the above configuration, optimal alignment between the substrate W and the mask M is performed.
FIG. 4 shows a state in which the substrate mark 10 is located within an allowable range (D tolerance) of the deviation D around the mask mark 20.
In the present invention, even when the substrate W is stretched (A), when it is shrunk (C), it is within the D tolerance, and in the standard case (B) is located at the center of the tolerance and is always optimal. It can be seen that accurate alignment can be performed.

Schematic which shows one Embodiment of this invention. Explanatory drawing which shows operation | movement of one Embodiment of this invention. The flowchart figure which shows operation | movement of one Embodiment of this invention. Explanatory drawing which shows the alignment state of one Embodiment of this invention.

Explanation of symbols

1: arithmetic control device, 2: moving mechanism, 3: platen, 4: CCD camera, 5: exposure light source, 6: shutter, 7: detection device, 8: discrimination / judgment device, 10: substrate mark, 20: mask mark .

Claims (4)

A plurality of substrate marks provided at a plurality of positions P of the substrate to be exposed and for aligning the substrate and a photomask depicting a pattern to be exposed;
A plurality of mask marks provided on the photomask corresponding to each of the plurality of substrate marks;
Means for aligning the substrate and the photomask, and detecting a shift Dp of the position of the mask mark corresponding to each substrate mark at each P point at that time;
Means for detecting a maximum value MDp of the deviation Dp;
Means for repeating the alignment N times and detecting the maximum value MDp of each time;
Means for detecting a minimum value MDmin among the N maximum values MDp;
Means for determining whether the minimum value MDmin is equal to or less than a predetermined value;
Means for determining the n- th alignment position from which the MDmin is obtained as the most appropriate alignment position when determined by the determining means to be equal to or less than a predetermined value;
An exposure apparatus comprising: A means for performing the N alignments by calculation ;
The exposure apparatus according to claim 1. A plurality of substrate marks provided at a plurality of positions P of the substrate to be exposed for aligning the substrate and a photomask depicting a pattern to be exposed, and corresponding to each of the plurality of substrate marks A plurality of mask marks provided on the photomask, and an alignment method for performing alignment based on the mask mark,
Performing alignment between the substrate and the photomask, and detecting a shift Dp of the position of the mask mark corresponding to each substrate mark at each P point at that time;
Detecting a maximum value MDp of the deviation Dp;
Repeating the alignment N times and detecting the maximum value MDp of each time;
Detecting a minimum value MDmin among the N maximum values MDp;
Determining whether the minimum value MDmin is less than or equal to a predetermined value;
Determining that the n- th alignment position from which the MDmin is obtained is the most appropriate alignment position when determined by the determining means to be equal to or less than a predetermined value;
An alignment method. Performing the N alignments by calculation ,
The alignment method according to claim 3.

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