JPH01260818A - Alignment mark attachment structure - Google Patents

Abstract

PURPOSE:To detect positions correctly in laser diffracted light treatment and the like, by forming dummy patterns at the positions in the vicinity of both sides of each alignment mark and mounting the dummy patterns after applying a designated resist layer on each upper layer of the foregoing patterns. CONSTITUTION:Dummy patterns 3 are mounted at both sides of each alignment mark 2. The dummy patterns 3 are formed by disposing them at designated intervals so that five sets of dummy pattern pieces 3a each of which is slightly longer than the length of the alignment mark 2 make up a diffraction grating. The dummy patterns 3 are mounted after applying a designated resist layer 4 on each upper layer of the patterns. In such a case, the whole parts where these alignment marks 2 and dummy patterns 3 are provided protrude upwards in the form of a trapezoid, and in this configuration the upper surface of each alignment mark 2 located on the center of the resist layer 4 which protrudes in the form of the trapezoid is almost horizontal. Since the surface of the resist layer corresponding to the alignment marks is held in the horizontal position, the signal waveform of each alignment mark always undergoes a uniform influence from the resist layer to have the signal waveform that is correctly correspondent to each alignment mark.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for attaching alignment marks provided on a wafer for aligning a projection exposure apparatus 1.

(Prior Art) In a projection exposure apparatus, when one pattern of a wafer is printed by exposure, it is necessary to align the projected image of the mask pattern with a set position on the wafer surface. For this purpose, it is necessary to accurately set the wafer at a set position on the wafer stage of the projection exposure apparatus, and at the time of setting, an alignment mark attached to the lower layer of the resist layer of the wafer is used as a guide.

Figure 2 (A) is a plan view showing the arrangement of conventional diffraction grating type alignment marks, and Figure 2 (B) is
FIG. 2(C) is a cross-sectional view of the wafer whose positional relationship corresponds to that of A), and a signal graph diagram whose positional relationship corresponds to that of FIGS.

In these figures, the symbol 10! is a wafer, 102 is a diffraction grating type alignment mark, and the alignment mark 102 is composed of seven mark pieces l02a arranged at predetermined intervals in the linear direction. The diffracted light formed by buffering the reflected lights from the piece 102a with each other travels in the direction of the arrow X,
It is designed to be obtained on both sides of the arrangement direction.

103 is a resist layer, and alignment mark 102
The portion corresponding to the alignment mark 102 has a convex shape.

The alignment mark 102 is detected when the wafer 101 is set in the projection exposure device when the laser beam from the laser diffraction light processing device is scanned and irradiated onto the wafer IO1 in the direction of the arrow, and the alignment mark 102 is irradiated. A diffracted light signal from the alignment mark 102 is obtained as shown in FIG. 2(C), and this signal waveform S
The peak position S corresponds to the center position C of the alignment mark 102.

Then, the center position C of this alignment mark 102 is aligned with a predetermined position of the wafer stage of the projection exposure apparatus.

(Problems to be Solved by the Invention) However, in the past, there was a problem that the positioning could not be performed accurately for the following reasons.

That is, resist layer 1 on alignment mark 102
03 is not symmetrical with respect to the center position C of the alignment mark 102, as shown in FIG. 2(B), but is provided asymmetrically, as shown in FIG. 2(C). As shown, the signal waveform S deviates from the actual alignment mark 102 due to the influence of the shape of the resist layer 103, and as a result, the center position S of the signal waveform S and the center position C of the alignment mark 102 no longer match. , an error in detecting the position of the alignment mark 102 occurs.

The present invention has been made in view of the above circumstances, and provides an alignment mark attachment structure that allows accurate position detection in laser diffraction light processing and the like.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an alignment mark attachment structure with dummy patterns at positions near both sides of the alignment mark when forming the alignment mark on the wafer surface. A resist layer is formed and provided thereon, and a resist layer is coated on top of the resist layer, and a portion of the resist layer located above the alignment mark and the dummy pattern protrudes integrally into a platform shape and corresponds to the alignment mark. The surface of the resist layer is a substantially horizontal surface.

(Function) With the above configuration, the surface of the resist layer corresponding to the alignment mark is a substantially horizontal plane, so when detecting the position of the alignment mark in laser diffraction light processing, etc., the signal waveform of the alignment mark is always influenced by the resist layer. is uniformly received, resulting in a signal waveform that accurately corresponds to the alignment mark, and by finding the center position of the signal waveform, the position of the alignment mark can be accurately detected.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1(A) is a plan view showing the arrangement of diffraction grating type alignment marks, FIG. 1(B) is a cross-sectional view of the wafer whose positional relationship corresponds to that of FIG. 1(A), and FIG. ) is a signal graph diagram whose positional relationship corresponds to that of FIGS. 1(A) and 1(B).

In these figures, reference numeral l denotes a wafer, each of 2a is an alignment mark piece forming a diffraction grating type alignment mark 2 as a whole, each of 3a is a dummy pattern piece forming a diffraction grating type dummy pattern 3 as a whole, 4 is a resist layer.

The alignment mark 2 is provided similarly to that shown in the conventional example, and dummy patterns 3 are provided on both sides of the alignment mark 2, respectively.

The dummy pattern 3 is formed by five dummy pattern pieces 3a whose length is slightly longer than the alignment mark 2 and arranged at predetermined intervals so as to constitute a diffraction grating.

The above alignment mark 2 and dummy pattern 3 are
It is provided in the same process. A resist layer 4 is integrally applied onto the alignment marks 2 and the dummy pattern 3.

Since the resist layer 4 is provided by coating, the entire portion where the alignment mark 2 and the dummy pattern 3 are provided protrudes upward in a table-like manner, and therefore,
The northern surface of the alignment mark 2 located at the center of the trapezoid-shaped layer 4 is a substantially horizontal surface.

As described above, since the northern surface of the alignment mark 2 of the Renost layer 4 is configured to be approximately horizontal, the waveform S of the diffracted light signal obtained when laser light is irradiated is as shown in FIG. 1(C). As shown, since it is uniformly influenced by the Lennost layer 4, the signal waveform S corresponds precisely to the alignment mark 2, and therefore the peak position S of the signal waveform S coincides with the center position C of the alignment mark 2. , Thereby, the position of the alignment mark 2 can be detected accurately.

Diffraction light is also generated when the laser beam 7 is irradiated onto the dummy pattern piece 3, but the direction of the diffraction is in the direction of the dummy pattern piece 3.
This is the direction of the arrow y, which is orthogonal to the diffraction direction X of the diffracted light obtained from the alignment mark 2 due to the arrangement direction of a.
Therefore, if a spatial filter is used on the diffracted light detection side, the diffracted light signal from the dummy pattern 3 can be easily removed, and thereby the diffracted light signal from only the alignment mark 2 can be detected. Note that, depending on the surface condition of the dummy pattern piece 3a, diffracted light in the same direction as the diffracted light from the alignment mark 2 is also generated from the dummy pattern 3;
As shown in FIG. 1(C), the signal strength is so weak that it does not interfere with position detection of the alignment mark 2.

In the above embodiment, the case where the position detection of the alignment mark is performed using the laser diffraction light processing device has been described, but the alignment mark attachment structure of the present invention is applicable when the position detection is performed using the ITV video signal processing device. In this case, the detection signal is obtained from both the alignment mark and the dummy pattern, so it is necessary to identify the detection signal by an appropriate method.

(Effects of the Invention) As described above, according to the present invention, the surface of the resist layer corresponding to the alignment mark is a substantially horizontal plane, and when detecting the position of the alignment mark in laser diffraction light processing, etc. Since a signal waveform that accurately corresponds to the alignment mark that has been uniformly affected by Positioning can now be done with high precision.

[Brief explanation of the drawing]

Each figure in FIG. 1 relates to the present invention, and FIG.
Figure (B) is a cross-sectional view of the wafer whose positional relationship corresponds to that of Figure 1(A), and Figure 1(C) is a signal graph diagram whose positional relationship corresponds to that of Figures 1(A) and (B). be. Each figure in Fig. 2 relates to a conventional example, Fig. 2 (A) is a plan view showing the arrangement configuration of the diffraction grating type alignment mark, and Fig. 2 (B) shows the positional relationship with Fig. 2 (A). The corresponding sectional view of the wafer, FIG. 2(C), is a signal graph diagram whose positional relationship corresponds to that of FIGS. 2(A) and 2(B). ! ... Wafer, 2... Alignment mark, 2a... Alignment mark piece, 3... Dummy pattern, 3a... Dummy pattern piece, 4... Renost layer. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) When forming alignment marks on the wafer surface,
A dummy pattern is formed near both sides of the alignment mark, and a resist layer is coated on top of the dummy pattern, and a portion of the resist layer located above the alignment mark and the dummy pattern is integrally formed. 1. An alignment mark attachment structure, characterized in that the surface of the resist layer protrudes in a trapezoidal shape and corresponds to the alignment mark is a substantially horizontal surface.