JPS6319853B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for manufacturing photomasks and reticle masks used in manufacturing semiconductor integrated circuits, solid-state image sensors, and the like.

(Technical Background of the Invention) It can be said that a semiconductor integrated circuit or a solid-state image sensing device usually consists of a common (general purpose) pattern and an individual pattern. Corresponding to this situation, the mask also naturally has a common pattern section and an individual pattern section. To explain this point with reference to Figures 1 and 2 of the drawings, Figure 1 shows an enlarged view of the pattern area of the mask corresponding to one chip of a solid-state image sensor or an integrated circuit element. Part 1 tends to have a large pattern such as bonding pad 2, which is specified for that type, and therefore has a fixed pattern. On the other hand, in the central part 3,
A unique pattern is formed by the elements. That is, in this case, the peripheral part 1 can be considered to be the common pattern part, and the central part 3 can be considered to correspond to the individual pattern part. Regarding Fig. 2, if an integrated circuit chip is viewed as a single functional element, for example, ROM (read only)
The memory portion 4 may vary individually depending on the role of each functional element, whereas the other portions 11 are often commonly used.

(Objective of the Invention) As described above, when one integrated circuit chip is taken, it is often possible to distinguish between a common pattern part and an individual pattern part. A method of manufacturing a suitable photomask or reticle mask (hereinafter simply referred to as a mask) is provided.

(Summary of the Invention) That is, when manufacturing a mask, the present invention first creates a common pattern mask having a light shielding layer patterned only in the common pattern portion, creates a large number of composite masks from this, and then A mask is obtained by patterning the individual pattern portions of the mask using a quantum beam exposure method such as an electron beam.

The mask of the present invention is formed by forming a light-shielding layer of photoresist that is opaque to the photosensitive area in a pattern on a transparent substrate, and the manufacturing method thereof is as follows (a).
It can be said that it comprises the steps of ~(f).

(a) A step of separating the light-shielding layer into a common pattern portion and an individual pattern portion, and forming a light-shielding layer corresponding to the common pattern portion in a pattern on a transparent substrate to create a common pattern mask; (b) the step of forming a common pattern mask; A step of creating a number of composite masks based on the pattern mask, in which the light shielding layer of the common pattern part is formed in a pattern while the individual pattern parts are blank; (c) the surface of the composite mask with the light shielding layer; (d) forming a quantum beam-sensitive resist layer on the individual pattern portions of the composite mask; forming a resist layer corresponding to a desired individual pattern on the pattern portion; (e) etching away the light shielding layer of the individual pattern portion that is not covered by the resist layer of the composite mask to shield the individual pattern portion from light; (f) removing the resist layer of the composite mask;

(Detailed Description of the Invention) The present invention will be specifically described below with reference to FIGS.

FIG. 4A is a schematic cross-sectional view showing the common pattern mask 8. FIG. In the figure, a transparent substrate 9 is made of quartz glass, low expansion glass, ordinary glass, etc., and a light shielding film 10 made of metal, metal compound, etc. is formed on its upper surface. However, in the light shielding film 10 at this time, only the light shielding film 10a of the common pattern part A shown in FIG. may be completely unpatterned or absent at all. Patterning of the light shielding film 10a of the common pattern portion A of the common pattern mask is performed by conventionally known means. For example, a resist layer sensitive to light, electron beams, and quantum rays such as A pattern is created by partially exposing a desired area using an electron beam exposure device, removing the uncured portion of the resist layer by development, and removing the portion of the light shielding film 10 not covered by the resist layer by an etching method. A light shielding film 10a having a shape is obtained.

On this common pattern mask 8, at least two or more alignment marks 5a are formed at arbitrary locations. This alignment mark 5a is for aligning the light shielding layers of the common pattern section A and the individual pattern section B in a later process, and the details will be described later.

Since the common pattern mask 8 is used to create a large number of composite masks 20 based on the common pattern mask 8, it is desirable that the mask be defect-free. The common pattern mask 8 shown in FIG. 4A schematically shows a black defect 12 in which a light-shielding film exists where it should not exist, and a white defect 13 in which a light-shielding layer does not exist in a place where it should exist. ing.

Common pattern mask 8 with such defects
The mask is modified as shown in FIG. 4B to obtain a defect-free mask. That is, for the black defect 12, unnecessary light shielding layer is removed by local etching method or laser repair method. Further, the white defect 13 is corrected by filling it with a light shielding material 14.

A large number of composite masks are created using the defect-free common pattern mask 8 thus obtained. As shown in FIG.
The photoresist layer 17 side of the mask blank plate 18 formed by laminating the above layers in this order is faced to the photoresist layer 17 side, and light is irradiated from the transparent substrate 9 side of the common pattern mask 8. In the embodiment shown in the figure, the common pattern mask 8 and the mask blank plate 18 are not in close contact with each other, but a close exposure method is used in which there is a slight gap between them. I don't mind.

Mask blank plate 1 is formed by the exposure operation shown in Fig. 4 (c).
A latent image is formed on the photoresist layer 17 of 8. This is subjected to predetermined resist development, resulting in a resist pattern layer 1 having a desired shape as shown in FIG. 4D.
9 is formed. Subsequently, the portion of the blank light-shielding layer 16 that is not covered with the resist pattern layer 19 is removed, and then the unnecessary resist pattern 19 is also peeled off, as shown in FIG. 4E. A composite mask 20 like this is obtained. Light shielding layer 16
In addition to a wet etching method using a corrosive solution, dry etching methods such as sputter etching, ion etching, and plasma etching may be used to remove the etchant. As long as there is only one common pattern mask 8, a large number of composite masks 20 can be created by repeating the steps shown in FIG.

As is already clear, in the illustrated embodiment, the portion of the photoresist layer 17 irradiated with light is dissolved and removed by development, and in this example, a positive type photoresist is used for the photoresist layer 17. It is something that exists. Photoresist layer 17
When using a negative photoresist, it is appropriate that the light shielding layer 10a of the common pattern mask 8 has a negative pattern. Common pattern mask 8
If the light shielding layer 10a has a positive pattern as shown in FIG. 4B, it is necessary to repeat the operations in FIG. 4C to H twice. However, there is nothing that cannot be done using this method, and it is naturally included in the present invention.

A quantum beam sensitive resist layer 21 is formed on the surface of the thus obtained composite mask 20 on which the light shielding layers 16 and 16a are located, resulting in the state shown in FIG. 4.
The quantum beam mentioned here includes light, ultraviolet light, electron beam, ion beam, laser light, etc.

Next, as shown in FIG.
A desired portion of the overlying quantum beam-sensitive resist layer 21 is exposed to quantum beams 22 . At this time, the resist layer 21 on the alignment mark 5b of the composite mask is also exposed to the quantum beam. The quantum beam-sensitive resist layer 21 on which the latent image has been formed is developed to form a resist layer 23 corresponding to a desired individual pattern on the light-shielding layer 16 of the individual pattern portion B, as shown in FIG. . Although the explanation has been complicated, it is preferable to use a positive type resist layer 21 as the quantum beam sensitive resist layer 21. The reason is that with a positive resist, the part irradiated with quantum beams is dissolved and removed by development, so the common pattern area A, which has already been patterned, does not need to be irradiated with quantum beams. Resist layer 23 after development
This is because it is possible to make the remaining.

This means that the common pattern portion A is not included as the exposure area of the quantum beam 22, and by reducing the exposure area, the time required for quantum beam, for example, electron beam exposure can be shortened, resulting in efficiency. .

Subsequently, in the state of FIG. 4H in which the common pattern part A is completely covered by the resist layer 23, the light shielding layer 16 of the individual pattern parts exposed and not covered by the resist layer 23 is removed by etching. As shown in FIG. 4, the light shielding layer 16b of the individual pattern portion B is formed. Exposed light shielding layer 16
Regarding the partial removal method, both wet etching and dry etching can be selected, as described when creating the common pattern portion A of the composite mask 20.

Finally, by removing the unnecessary resist layer 23, a mask 24 having light shielding layers 16a and 16b in the common pattern part A and the individual pattern part B on the transparent substrate 15 is completed, as shown in FIG. do.

Here, to explain the alignment marks in the present invention, it is preferable to provide a plurality of alignment marks as illustrated as alignment marks 5 in FIGS. 1 and 2. In one piece,
This is because it is difficult to recognize the amount of deviation in the angular direction. However, regarding the position of the alignment mark 5,
In the figure, it is provided in the individual pattern part, and in FIG. 2, it is provided in the common pattern part, so it may be provided at any arbitrary location, for example, it may be provided in the outer frame other than the common/individual pattern part.

An example of the shape of the alignment mark 5 shown in FIG. 3 is shown. The mark 6 consisting of four rectangles was drawn when patterning the common pattern section, and the cross-shaped mark 7 was drawn at the same time when patterning the individual pattern section. The alignment mark 5 shown in FIG. 3 is in an ideal state, indicating that there is no relative positional deviation between the common pattern section and the individual pattern section. If a semiconductor integrated circuit is created using a mask that has a significant deviation between the common pattern part and the individual pattern part, it may not function properly and the alignment mark 5
can be said to be used to test this.

(Effects of the Invention) The present invention is a method of manufacturing a mask as described above, in which a large number of composite masks each having a light-shielding layer in which only a common pattern part is patterned is prepared in advance, and individual pattern parts are changed according to demand. Since this is a method of patterning a mask, it is possible to keep the common pattern portion free of defects when creating a composite mask, which has the advantage of improving the yield of masks. Moreover, since the area of the individual pattern part is smaller than the entire mask area, when drawing the individual pattern part by electron beam exposure using a raster scan method, for example, the time required for drawing the individual pattern part is shorter than the drawing area because the drawing area is small. It has the advantage of being completed in a short amount of time, reducing the time from mask generation to delivery.

Furthermore, when assuming that the common pattern is a large pattern with a relatively large area, such as a bonding pad in a chip, it is better to use a rectangular division method to draw such a pattern than a raster scan electron beam exposure method. There is a sense that drawing with a generator can be done more efficiently,
Another advantage is that an appropriate drawing method can be selected from among several types of quantum rays for drawing the common pattern portion. In addition, the common pattern portion and the individual pattern portion can be accurately combined by providing alignment marks.

As described above, the present invention is applicable to a method of manufacturing a mask for manufacturing semiconductor integrated circuits, for example, a mask having a portion with a strong individual pattern character, such as a gate array of an aluminum wiring pattern, a ROM portion of an arithmetic circuit chip, or a bonding pad. If used in the manufacture of a mask or the like in which the pattern density is different between a common pattern part such as a board and an individual pattern part, it will exhibit extremely excellent effects.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view showing an example of a mask pattern corresponding to one chip of a solid-state image sensor or an integrated circuit device, and FIG. 2 is an example of a form of a mask pattern suitable for the mask manufacturing method of the present invention. FIG. FIG. 3 is an enlarged plan view showing an example of the alignment mark, and FIGS. 4A to 4C are explanatory cross-sectional views showing one embodiment of the mask manufacturing method of the present invention in the order of steps. 5... Alignment mark, 8... Common pattern mask, 18... Mask blank board, 20... Composite mask, 24... Mask, A... Common pattern section, B... Individual pattern section.

Claims (1)

[Claims] 1. A method for manufacturing a mask for manufacturing a semiconductor integrated circuit in which a light-shielding layer of photoresist that is opaque to the photosensitive area is formed in a pattern on a transparent substrate, in which (a) the light-shielding layer is formed as a common pattern portion; (b) forming a common pattern mask by forming a light-shielding layer corresponding to the common pattern part on a transparent substrate in the form of a pattern; (b) forming a common pattern mask on the basis of the common pattern mask; (c) forming a quantum beam-sensitive resist layer on the side of the composite mask where the light shielding layer is located; (d) A desired portion of the quantum beam-sensitive resist layer on the individual pattern portion of the composite mask is exposed to quantum beams and developed to form a desired individual pattern on the individual pattern portion. (e) forming a light shielding layer in the individual pattern portions in a pattern by etching away the light shielding layer in the individual pattern portions that are not covered by the resist layer of the composite mask; f) a step of removing a resist layer of a composite mask; A method for manufacturing a mask, comprising the steps (a) to (f) above.